National Library of Energy BETA

Sample records for turbulent jet ignition

  1. Spark ignition of lifted turbulent jet flames

    SciTech Connect (OSTI)

    Ahmed, S.F.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2006-07-15

    This paper presents experiments on ignition and subsequent edge flame propagation in turbulent nonpremixed methane jets in air. The spark position, energy, duration, electrode diameter and gap, and the jet velocity and air premixing of the fuel stream are examined to study their effects on the ignition probability defined as successful flame establishment. The flame is visualized by a high-speed camera and planar laser-induced fluorescence of OH. It was found that after an initially spherical shape, the flame took a cylindrical shape with a propagating edge upstream. The probability of successful ignition increases with high spark energy, thin electrode diameter and wide gap, but decreases with increasing dilution of the jet with air. The flame kernel growth rate is high when the ignition probability is high for all parameters, except for jet velocity. Increasing the jet velocity decreases the ignition probability at all locations. The average flame position as a function of time from the spark was measured and the data were used to estimate a net propagation speed, which then resulted in an estimate of the average edge flame speed relative to the incoming flow. This was about 3 to 6 laminar burning velocities of a stoichiometric mixture. The measurements can assist theoretical models for the probability of ignition of nonpremixed flames and for edge flame propagation in turbulent inhomogeneous mixtures, both of which determine the success of ignition in practical combustion systems. (author)

  2. Plasma jet ignition device

    DOE Patents [OSTI]

    McIlwain, Michael E. (Franklin, MA); Grant, Jonathan F. (Wayland, MA); Golenko, Zsolt (North Reading, MA); Wittstein, Alan D. (Fairfield, CT)

    1985-01-15

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  3. One-dimensional turbulence model simulations of autoignition of hydrogen/carbon monoxide fuel mixtures in a turbulent jet

    SciTech Connect (OSTI)

    Gupta, Kamlesh G.; Echekki, Tarek [Department of Mechanical and Aerospace Engineering, North Carolina State University, NC (United States)

    2011-02-15

    The autoignition of hydrogen/carbon monoxide in a turbulent jet with preheated co-flow air is studied using the one-dimensional turbulence (ODT) model. The simulations are performed at atmospheric pressure based on varying the jet Reynolds number and the oxidizer preheat temperature for two compositions corresponding to varying the ratios of H{sub 2} and CO in the fuel stream. Moreover, simulations for homogeneous autoignition are implemented for similar mixture conditions for comparison with the turbulent jet results. The results identify the key effects of differential diffusion and turbulence on the onset and eventual progress of autoignition in the turbulent jets. The differential diffusion of hydrogen fuels results in a reduction of the ignition delay relative to similar conditions of homogeneous autoignition. Turbulence may play an important role in delaying ignition at high-turbulence conditions, a process countered by the differential diffusion of hydrogen relative to carbon monoxide; however, when ignition is established, turbulence enhances the overall rates of combustion of the non-premixed flame downstream of the ignition point. (author)

  4. Turbulent Jets SUMMARY: This chapter is concerned with turbulent jets, namely their overall

    E-Print Network [OSTI]

    Cushman-Roisin, Benoit

    Chapter 9 Turbulent Jets SUMMARY: This chapter is concerned with turbulent jets, namely their overall shape and velocity structure. The first jets being considered are those penetrating in homogeneous terminology. Continuous Intermittent injection injection Momentum only Jet Puff Buoyancy only Plume Thermal

  5. Turbulent round jet under gravity waves 

    E-Print Network [OSTI]

    Ryu, Yong Uk

    2002-01-01

    The behavior of a neutrally buoyant horizontal turbulent round jet under a wavy environment was investigated. Progressive waves with different wave amplitudes in an intermediate water depth were used. The Particle Image Velocimetry (PIV) technique...

  6. The turbulent/non-turbulent interface at the outer boundary of a self-similar turbulent jet

    E-Print Network [OSTI]

    Hunt, Julian

    The turbulent/non-turbulent interface at the outer boundary of a self-similar turbulent jet J-similar turbulent jet at Re=2·103 is investigated ex- perimentally by means of combined particle image velo- cimetry (PIV) laser-induced fluorescence (LIF) measurements. The jet fluid contains a fluorescent dye so

  7. Can Protostellar Jets Drive Supersonic Turbulence in Molecular Clouds?

    E-Print Network [OSTI]

    Robi Banerjee; Ralf S. Klessen; Christian Fendt

    2007-06-25

    Jets and outflows from young stellar objects are proposed candidates to drive supersonic turbulence in molecular clouds. Here, we present the results from multi-dimensional jet simulations where we investigate in detail the energy and momentum deposition from jets into their surrounding environment and quantify the character of the excited turbulence with velocity probability density functions. Our study include jet--clump interaction, transient jets, and magnetised jets. We find that collimated supersonic jets do not excite supersonic motions far from the vicinity of the jet. Supersonic fluctuations are damped quickly and do not spread into the parent cloud. Instead subsonic, non-compressional modes occupy most of the excited volume. This is a generic feature which can not be fully circumvented by overdense jets or magnetic fields. Nevertheless, jets are able to leave strong imprints in their cloud structure and can disrupt dense clumps. Our results question the ability of collimated jets to sustain supersonic turbulence in molecular clouds.

  8. The deterministic chaos and random noise in turbulent jet

    SciTech Connect (OSTI)

    Yao, Tian-Liang; Liu, Hai-Feng Xu, Jian-Liang; Li, Wei-Feng

    2014-06-01

    A turbulent flow is usually treated as a superposition of coherent structure and incoherent turbulence. In this paper, the largest Lyapunov exponent and the random noise in the near field of round jet and plane jet are estimated with our previously proposed method of chaotic time series analysis [T. L. Yao, et al., Chaos 22, 033102 (2012)]. The results show that the largest Lyapunov exponents of the round jet and plane jet are in direct proportion to the reciprocal of the integral time scale of turbulence, which is in accordance with the results of the dimensional analysis, and the proportionality coefficients are equal. In addition, the random noise of the round jet and plane jet has the same linear relation with the Kolmogorov velocity scale of turbulence. As a result, the random noise may well be from the incoherent disturbance in turbulence, and the coherent structure in turbulence may well follow the rule of chaotic motion.

  9. Implicit LES Simulation of Two phase Turbulent Jet Flow

    E-Print Network [OSTI]

    McDonald, Kirk

    Implicit LES Simulation of Two phase Turbulent Jet Flow Feb. 27th 2014 Yan 1 #12;Studied ProblemsD 2120 297 629,640 2 #12;Results 3JetDiameter Case · VOF 3 Initialization (t = 0 s) Z Z #12;Results 3JetDiameter Case (click to watch the movie) 4 · VOF 0 Jet

  10. Formation of Jets by Baroclinic Turbulence BRIAN F. FARRELL

    E-Print Network [OSTI]

    Farrell, Brian F.

    Formation of Jets by Baroclinic Turbulence BRIAN F. FARRELL Department of Earth and Planetary spatial-scale jets; geophysical examples of this phenomenon include the Jovian banded winds and the earth's polar-front jet. These relatively steady large-scale jets arise from and are maintained by the smaller

  11. Turbulence transition and internal wave generation in density stratified jets

    E-Print Network [OSTI]

    Sutherland, Bruce

    Turbulence transition and internal wave generation in density stratified jets B. FL Sutherland (Received 3 June 1993; accepted 18 November 1993) The nonlinear evolution of an unstable symmetric jet torques. In this case, the mean flow of the fully evolved jet is stable to subharmonic disturbances

  12. Modeling of Noise Reduction for Turbulent Jets with Induced Asymmetry

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    (flight) conditions I. Introduction The exhaust of jet engines continues to be a significant contributorModeling of Noise Reduction for Turbulent Jets with Induced Asymmetry Dimitri Papamoschou and Sara for the noise reduction of dual-stream jets with induced asymmetry in the plume flow field, with emphasis

  13. Simulations of High Speed Turbulent Jets in Crossflows Xiaochuan Chai

    E-Print Network [OSTI]

    Mahesh, Krishnan

    of the turbulent mixing mechanisms are important in combustor design. Supersonic jets are used for attitude or roll crossflows of two different Mach numbers and showed the presence of large-scale stuctures. Kawai and Lele7

  14. Simulations of High Speed Turbulent Jets in Crossflow Xiaochuan Chai

    E-Print Network [OSTI]

    Mahesh, Krishnan

    understanding of the turbulent mixing mechanisms play important roles in combustor design. Supersonic jets used crossflows of two different Mach numbers and showed the presence of large-scale stuctures. Kawai and Lele7

  15. Micro-jets in confined turbulent cross flow

    SciTech Connect (OSTI)

    Kelman, J.B.; Greenhalgh, D.A. [School of Engineering, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Whiteman, M. [Rolls-Royce plc, Combustion systems, Moor Lane, Derby DE24 8BJ (United Kingdom)

    2006-03-01

    The mixing of sub-millimetre diameter jets issuing into a turbulent cross flow is examined with a combination of laser diagnostic techniques. The cross flow stream is in a confined duct and the micro-jet issue from the sides of injector vanes. A range of cross jet momentum ratios, cross flow temperatures and turbulence intensities are investigated to examine the influence on the jet mixing. Methane, seeded with acetone, was used to measure the concentrations of the jets and the mixing of the jet fluid in the duct. Unlike previous jet in cross flow work, mixing appears to be dominated by the free stream turbulence, rather than the cross jet momentum ratios. Temperature increases in the free stream appear to increase the rate of mixing in the duct, despite the associated decrease in the Reynolds number. The dominance of the free stream turbulence in controlling the mixing is of particular interest in respect of gas turbine injection systems, as the cross jet momentum ratio is insufficient in defining the mixing process. (author)

  16. Paper No. 150. Ray, Najm and McCoy 1 Ignition front structure in a methane-air jet.1

    E-Print Network [OSTI]

    Ray, Jaideep

    Paper No. 150. Ray, Najm and McCoy 1 Ignition front structure in a methane-air jet.1 J.Ray2 , H. N-premixed methane jet in coflow air using the GRImech1.2 chemical mechanism. Ignition is initiated in the jet mixing is formed in the rich mixture region inside the jet and is observed to propagate towards the stoichiometric

  17. Reduced-Order Modelling of Turbulent Jets for Noise Control

    E-Print Network [OSTI]

    École Normale Supérieure

    Reduced-Order Modelling of Turbulent Jets for Noise Control Michael Schlegel, Bernd R. Noack, an opportunity for model-based jet noise reduction is opening up by the rapidly evolving field of reduced and Gilead Tadmor Abstract A reduced-order modelling (ROM) strategy is pursued to achieve a mech- anistic

  18. Characterization of turbulent jet mixing in cylindrical tanks 

    E-Print Network [OSTI]

    Schulte, Casey M

    1998-01-01

    This objective of this thesis is to investigate the aphics. mixing offered by turbulent jets. This study focuses on the specific application of low viscosity jets (1-30 cP) introduced for the purpose of mixing non-stratifying, miscible fluids...

  19. Auto-ignition during instationary jet evolution of dimethyl ether (DME) in a high-pressure atmosphere

    SciTech Connect (OSTI)

    Fast, G.; Kuhn, D.; Class, A.G.; Maas, U.

    2009-01-15

    The auto-ignition process during transient injection of gaseous dimethyl ether (DME) in a constant high-pressure atmosphere is studied experimentally by laser-optical methods and compared with numerical calculations. With different non-intrusive measurement techniques jet properties and auto-ignition are investigated at high temporal and spatial resolution. The open jet penetrates a constant pressure oxidative atmosphere of up to 4 MPa. During the transient evolution, the fuel jet entrains air at up to 720 K. The subsequent auto-ignition of the ignitable part of the jet occurs simultaneously over a wide spatial extension. The ignition delay times are not affected by variation of the nozzle exit velocity. Thus, the low-temperature oxidation is slow compared with the shorter time scales of mixing, so that chemical kinetics is dominating the process. The typical two-stage ignition is resolved optically with high-speed shadowgraphy at a sampling rate of 10 kHz. The 2D fields of jet velocity and transient mixture fraction are measured phase-coupled with Particle Image Velocimetry (PIV) and Tracer Laser Induced Fluorescence (LIF) during the time-frame of ignition. The instationary Probability Density Functions (PDF) of mixture fraction are described very well by Beta functions within the complete area of the open jet. Additional 1D flamelet simulations of the auto-ignition process are computed with a detailed reaction mechanism for DME [S. Fischer, F. Dryer, H. Curran, Int. J. Chem. Kinet. 32 (12) (2000) 713-740; H. Curran, S. Fischer, F. Dryer, Int. J. Chem. Kinet. 32 (12) (2000) 741-759]. Calculated ignition delay times are in very good agreement with the measured mean ignition delay times of 3 ms. Supplemental flamelet simulations address the influence of DME and air temperature, pressure and strain. Underneath a critical strain rate the air temperature is identified to be the most sensitive factor on ignition delay time. (author)

  20. Mixing at the external boundary of a submerged turbulent jet

    E-Print Network [OSTI]

    A. Eidelman; T. Elperin; N. Kleeorin; G. Hazak; I. Rogachevskii; O. Sadot; I. Sapir-Katiraie

    2009-05-11

    We study experimentally and theoretically mixing at the external boundary of a submerged turbulent jet. In the experimental study we use Particle Image Velocimetry and an Image Processing Technique based on the analysis of the intensity of the Mie scattering to determine the spatial distribution of tracer particles. An air jet is seeded with the incense smoke particles which are characterized by large Schmidt number and small Stokes number. We determine the spatial distributions of the jet fluid characterized by a high concentration of the particles and of the ambient fluid characterized by a low concentration of the tracer particles. In the data analysis we use two approaches, whereby one approach is based on the measured phase function for the study of the mixed state of two fluids. The other approach is based on the analysis of the two-point second-order correlation function of the particle number density fluctuations generated by tangling of the gradient of the mean particle number density by the turbulent velocity field. This gradient is formed at the external boundary of a submerged turbulent jet. We demonstrate that PDF of the phase function of a jet fluid penetrating into an external flow and the two-point second-order correlation function of the particle number density do not have universal scaling and cannot be described by a power-law function. The theoretical predictions made in this study are in a qualitative agreement with the obtained experimental results.

  1. ENHANCED IGNITION FOR I.C. ENGINES WITH PREMIXED CHARGE

    E-Print Network [OSTI]

    Dale, J.D.

    2013-01-01

    Stratified Charge Engines Flame Jet Igniters Combustion Jetand testing of jet igniters in engines was reported by Asikstratified charge engines; (6) flame jet igniters; (7)

  2. Large-eddy simulation of turbulent circular jet flows

    SciTech Connect (OSTI)

    Jones, S. C.; Sotiropoulos, F.; Sale, M. J.

    2002-07-01

    This report presents a numerical method for carrying out large-eddy simulations (LES) of turbulent free shear flows and an application of a method to simulate the flow generated by a nozzle discharging into a stagnant reservoir. The objective of the study was to elucidate the complex features of the instantaneous flow field to help interpret the results of recent biological experiments in which live fish were exposed to the jet shear zone. The fish-jet experiments were conducted at the Pacific Northwest National Laboratory (PNNL) under the auspices of the U.S. Department of Energy’s Advanced Hydropower Turbine Systems program. The experiments were designed to establish critical thresholds of shear and turbulence-induced loads to guide the development of innovative, fish-friendly hydropower turbine designs.

  3. Oscillations of a Turbulent Jet Incident Upon an Edge

    SciTech Connect (OSTI)

    J.C. Lin; D. Rockwell

    2000-09-19

    For the case of a jet originating from a fully turbulent channel flow and impinging upon a sharp edge, the possible onset and nature of coherent oscillations has remained unexplored. In this investigation, high-image-density particle image velocimetry and surface pressure measurements are employed to determine the instantaneous, whole-field characteristics of the turbulent jet-edge interaction in relation to the loading of the edge. It is demonstrated that even in absence of acoustic resonant or fluid-elastic effects, highly coherent, self-sustained oscillations rapidly emerge above the turbulent background. Two clearly identifiable modes of instability are evident. These modes involve large-scale vortices that are phase-locked to the gross undulations of the jet and its interaction with the edge, and small-scale vortices, which are not phase-locked. Time-resolved imaging of instantaneous vorticity and velocity reveals the form, orientation, and strength of the large-scale concentrations of vorticity approaching the edge in relation to rapid agglomeration of small-scale vorticity concentrations. Such vorticity field-edge interactions exhibit rich complexity, relative to the simplified pattern of vortex-edge interaction traditionally employed for the quasi-laminar edgetone. Furthermore, these interactions yield highly nonlinear surface pressure signatures. The origin of this nonlinearity, involving coexistence of multiple frequency components, is interpreted in terms of large- and small-scale vortices embedded in distributed vorticity layers at the edge. Eruption of the surface boundary layer on the edge due to passage of the large-scale vortex does not occur; rather apparent secondary vorticity concentrations are simply due to distension of the oppositely-signed vorticity layer at the tip of the edge. The ensemble-averaged turbulent statistics of the jet quickly take on an identity that is distinct from the statistics of the turbulent boundary layer in the channel. Large increases in Reynolds stress occur due to onset of the small-scale concentrations of vorticity immediately downstream of separation; substantial increases at locations further downstream arise from development of the large-scale vorticity concentrations.

  4. Second-order model of entrainment in planar turbulent jets at low Reynolds number S. Paillat and E. Kaminski

    E-Print Network [OSTI]

    Kaminski, Edouard

    Second-order model of entrainment in planar turbulent jets at low Reynolds number S. Paillat and E.1063/1.4767535 Investigations on the local entrainment velocity in a turbulent jet Phys. Fluids 24, 105110 (2012); 10-order model of entrainment in planar turbulent jets at low Reynolds number S. Paillata) and E. Kaminski

  5. LES of an Inclined Jet into a Supersonic Turbulent Crossflow

    E-Print Network [OSTI]

    Ferrante, Antonino; Dimotakis, Paul E; Stephens, Mike; Adams, Paul; Walters, Richard

    2009-01-01

    This short article describes flow parameters, numerical method, and animations of the fluid dynamics video "LES of an Inclined Jet into a Supersonic Turbulent Crossflow" (http://ecommons.library.cornell.edu/bitstream/1813/14073/3/GFM-2009.mpg [high-resolution] and http://ecommons.library.cornell.edu/bitstream/1813/14073/2/GFM-2009-web.m1v [low-resolution] video). We performed large-eddy simulation with the sub-grid scale (LES-SGS) stretched-vortex model of momentum and scalar transport to study the gas-dynamics interactions of a helium inclined round jet into a supersonic ($M=3.6$) turbulent (\\Reth$ =13\\times10^3$) air flow over a flat surface. The video shows the temporal development of Mach-number and magnitude of density-gradient in the mid-span plane, and isosurface of helium mass-fraction and $\\lam_2$ (vortical structures). The identified vortical structures are sheets, tilted tubes, and discontinuous rings. The vortical structures are shown to be well correlated in space and time with helium mass-fracti...

  6. Bayesian calibration of a k -turbulence model for predictive jet-in-crossflow simulations

    E-Print Network [OSTI]

    Ray, Jaideep

    Bayesian calibration of a k - turbulence model for predictive jet-in-crossflow simulations Jaideep skill in jet-in-crossflow simulations. The method is based on the hypotheses that (1) informative features of jet-in-crossflow interactions and (2) one can construct surrogates of RANS models

  7. Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline protection

    E-Print Network [OSTI]

    Abdou, Mohamed

    Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline ion inertial fusion reactors utilize banks of liquid jets and vortex flow tubes to protect sensitive observations and quantitative data for rectangular and circular jets are compared in an effort to illuminate

  8. Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline protection

    E-Print Network [OSTI]

    California at Los Angeles, University of

    Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline reactors utilize banks of liquid jets and vortex flow tubes to protect sensitive beam line components from for rectangular and circular jets are compared in an effort to illuminate the critical phenomena involved

  9. Parabolized stability equation models for predicting large-scale mixing noise of turbulent round jets

    E-Print Network [OSTI]

    Colonius, Tim

    jets D. Rodr´iguez1 , A. Samanta1 , A. V. G. Cavalieri2 , T. Colonius1§ and P. Jordan2¶ 1 Department-frequency, large-scale wavepacket structures and their radiated sound in high- speed turbulent round jets. Linear envelope and phase measured using a microphone array placed just outside the jet shear layer.1,2 Here we

  10. Emergence of Jets from Turbulence in the Shallow-Water Equations on an Equatorial Beta Plane

    E-Print Network [OSTI]

    Farrell, Brian F.

    Emergence of Jets from Turbulence in the Shallow-Water Equations on an Equatorial Beta Plane BRIAN (Manuscript received 2 September 2008, in final form 24 April 2009) ABSTRACT Coherent jets, such as the Jovian the essential mechanism of jet formation, which is systematic eddy mo- mentum flux directed up the mean velocity

  11. DNS of the effects of thermal stratification and turbulent mixing on H2/air ignition in a constant volume, and comparison with the

    E-Print Network [OSTI]

    Im, Hong G.

    DNS of the effects of thermal stratification and turbulent mixing on H2/air ignition in a constant of Mechanical Engineering University of Michigan, Ann Arbor, MI 48109-2125 Abstract The influence of thermal stratification on auto-ignition at constant volume and high pressure is studied by Direct Numerical Simulation

  12. ANALYSIS OF TURBULENT MIXING JETS IN LARGE SCALE TANK

    SciTech Connect (OSTI)

    Lee, S; Richard Dimenna, R; Robert Leishear, R; David Stefanko, D

    2007-03-28

    Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump for sludge mixing and removal operations with high-velocity liquid jets in one of the large-scale Savannah River Site waste tanks, Tank 18. This paper describes the computational model, the flow measurements used to provide validation data in the region far from the jet nozzle, the extension of the computational results to real tank conditions through the use of existing sludge suspension data, and finally, the sludge removal results from actual Tank 18 operations. A computational fluid dynamics approach was used to simulate the sludge removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model. Both the computational approach and the models were validated with onsite test data reported here and literature data. The model was then extended to actual conditions in Tank 18 through a velocity criterion to predict the ability of the new pump design to suspend settled sludge. A qualitative comparison with sludge removal operations in Tank 18 showed a reasonably good comparison with final results subject to significant uncertainties in actual sludge properties.

  13. Medium-induced jet evolution: wave turbulence and energy loss

    E-Print Network [OSTI]

    Leonard Fister; Edmond Iancu

    2014-09-06

    We study the gluon cascade generated via successive medium-induced branchings by an energetic parton propagating through a dense QCD medium. We focus on the high-energy regime where the energy $E$ of the leading particle is much larger than the characteristic medium scale $\\omega_c=\\hat q L^2/2$, with $\\hat q$ the jet quenching parameter and $L$ the distance travelled through the medium. In this regime the leading particle loses only a small fraction $\\sim\\alpha_s(\\omega_c/E)$ of its energy and can be treated as a steady source of radiation for gluons with energies $\\omega\\le\\omega_c$. For this effective problem with a source, we obtain exact analytic solutions for the gluon spectrum and the energy flux. The solutions exhibit wave turbulence: the basic physical process is a continuing fragmentation which is `quasi-democratic' (i.e. quasi-local in energy) and which provides an energy transfer from the source to the medium at a rate (the energy flux $\\mathcal{F}$) which is quasi-independent of $\\omega$. The locality of the branching process implies a spectrum of the Kolmogorov-Obukhov type, i.e. a power-law spectrum which is a fixed point of the branching process and whose strength is proportional to the energy flux: $D(\\omega)\\sim\\mathcal{F}/\\sqrt\\omega$ for $\\omega\\ll\\omega_c$. Via this turbulent flow, the gluon cascade loses towards the medium an energy $\\Delta E\\sim\\alpha_s^2\\omega_c$, which is independent of the initial energy $E$ of the leading particle and of the details of the thermalization mechanism at the low-energy end of the cascade. This energy is carried away by very soft gluons, which propagate at very large angles with respect to the jet axis. Our predictions for the value of $\\Delta E$ and for its angular distribution appear to agree quite well, qualitatively and even semi-quantitatively, with the phenomenology of di-jet asymmetry in nucleus-nucleus collisions at the LHC.

  14. The use of turbulent jets to destratify the Charles River Basin

    E-Print Network [OSTI]

    Church, Jeffrey H. (Jeffrey Harrison)

    2012-01-01

    This study examines the feasibility of using turbulent jets to destratify the Lower Charles River Basin between the Longfellow and Craigie Bridges between Boston and Cambridge. The basin is currently filled with salt water ...

  15. 43rd AIAA Aerospace Sciences Meeting and Exhibit, Jan 1013, Reno, Nevada Direct numerical simulation of turbulent jets in crossflow

    E-Print Network [OSTI]

    Mahesh, Krishnan

    simulation of turbulent jets in crossflow Suman Muppidi and Krishnan Mahesh University of Minnesota, Minneapolis, MN, 55455, USA Direct numerical simulations are used to study a round turbulent jet in a laminar crossflow. The velocity ratio of the jet to that of the crossflow is 5.7 and the Reynolds number based

  16. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    SciTech Connect (OSTI)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard

    2014-08-15

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re{sub D} = 18?100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data.

  17. Ignition of ethane, propane, and butane in counterflow jets of cold fuel versus hot air under variable pressures

    SciTech Connect (OSTI)

    Fotache, C.G.; Wang, H.; Law, C.K.

    1999-06-01

    This study investigates experimentally the nonpremixed ignition of ethane, propane, n-butane, and isobutane in a configuration of opposed fuel versus heated air jets. For each of these fuels the authors explore the effects of inert dilution, system pressure, and flow strain rate, for fuel concentrations ranging between 3--100% by volume, pressures between 0.2 and 8 atm, and strain rates of 100--600 s{sup {minus}1}. Qualitatively, these fuels share a number of characteristics. First, flame ignition typically occurs after an interval of mild oxidation, characterized by minimal heat release, fuel conversion, and weak light emission. The temperature extent of this regime decreases with increasing the fuel concentration, the ambient pressure, or the flow residence time. Second, the response to strain rate, pressure, and fuel concentration is similar for all investigated fuels, in that the ignition temperatures monotonically decrease with increasing fuel content, decreasing flow strain, and increasing ambient pressure. The C{sub 4} alkanes, however, exhibit three distinct p-T ignition regimes, similar to the homogeneous explosion limits. Finally, at 1 atm, 100% fuel, and a fixed flow strain rate the ignition temperature increases in the order of ethane < propane < n-butane < i-butane. Numerical simulation was conducted for ethane ignition using detailed reaction kinetics and transport descriptions. The modeling results suggest that ignition for all fuels studied at pressures below 5 atm is initiated by fuel oxidation following the high-temperature mechanism of radical chain branching and with little contribution by low-to-intermediate temperature chemistry.

  18. VELOCITY FIELD OF A ROUND TURBULENT TRANSVERSE JET Suman Muppidi

    E-Print Network [OSTI]

    Mahesh, Krishnan

    - bulent jet in a laminar crossflow. The velocity ratio is 5.7 and the Reynolds number is 5000. Mean Jets in crossflow, also called `transverse jets' are defined as the flow field where a jet of fluid enters and interacts with a crossflowing fluid. Examples of jets in crossflow are fuel injectors

  19. Random Vortex-Street Model for a Self-Similar Plane Turbulent Jet

    E-Print Network [OSTI]

    Victor L'vov; Anna Pomyalov; Itamar Procaccia; Rama Govindarajan

    2008-03-18

    We ask what determines the (small) angle of turbulent jets. To answer this question we first construct a deterministic vortex-street model representing the large scale structure in a self-similar plane turbulent jet. Without adjustable parameters the model reproduces the mean velocity profiles and the transverse positions of the large scale structures, including their mean sweeping velocities, in a quantitative agreement with experiments. Nevertheless the exact self similar arrangement of the vortices (or any other deterministic model) necessarily leads to a collapse of the jet angle. The observed (small) angle results from a competition between vortex sweeping tending to strongly collapse the jet and randomness in the vortex structure, with the latter resulting in a weak spreading of the jet.

  20. Experimental observations on transition to turbulence in confined coaxial jets and other boundary layer flows

    SciTech Connect (OSTI)

    Gore, R.A. (Los Alamos National Lab., NM (USA)); Crowe, C.T. (Washington State Univ., Pullman, WA (USA). Dept. of Mechanical and Materials Engineering); Bejan, A. (Duke Univ., Durham, NC (USA). Dept. of Mechanical Engineering and Materials Science)

    1990-01-01

    Experiments performed demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. The critical Reynolds number is shown to be a strong function of velocity ratio. From the flow visualization it is shown that a proportionality between the laminar length of the jet (L) and the wavelength ({lambda}) can be seen in the region of transition to turbulence. The proportionality coincides with similar observations concerning the transition to turbulence in various other flows. A brief argument based on scale analysis is presented for the confined coaxial jet and round plume. The apparent universality of the L/{lambda} {approximately} O(10) scaling law supports the conclusion that the laminar sections of all naturally progressing boundary layer-type flows are geometrically similar. 21 refs., 8 figs.

  1. Abstract--The sound generated during the production of the sibilant [s] results from the impact of a turbulent jet on the

    E-Print Network [OSTI]

    Van Hirtum, Annemie

    of a turbulent jet on the incisors. Physical modeling of this phenomenon depends on the characterization by the development of a jet of air in the oral tract. The interaction of this jet with different components at the origin of the different fricative sounds. The sibilant [s] results from the impact of a turbulent jet

  2. Magnetohydrodynamic lattice Boltzmann simulations of turbulence and rectangular jet flow 

    E-Print Network [OSTI]

    Riley, Benjamin Matthew

    2009-05-15

    relaxation time (SRT) parameter for the Maxwell’s stress tensor is developed for this study. In the MHD homogeneous turbulence studies, the kinetic/magnetic energy and enstrophy decays, kinetic enstrophy evolution, and vorticity alignment with the strain...

  3. An evaluation of linear instability waves as sources of sound in a supersonic turbulent jet

    E-Print Network [OSTI]

    Colonius, Tim

    instability wave at any given frequency as representative of the energy carrying wave componentAn evaluation of linear instability waves as sources of sound in a supersonic turbulent jet Kamran Mohsenia) Division of Engineering and Applied Science, California Institute of Technology, Pasadena

  4. Multi-Spacecraft Measurement of Turbulence within a Magnetic Reconnection Jet

    E-Print Network [OSTI]

    Osman, K T; Matthaeus, W H; Hnat, B; Chapman, S C; Khotyaintsev, Yu V

    2015-01-01

    The relationship between magnetic reconnection and plasma turbulence is investigated using multipoint in-situ measurements from the Cluster spacecraft within a high-speed reconnection jet in the terrestrial magnetotail. We show explicitly that work done by electromagnetic fields on the particles, $\\mathbf{J}\\cdot\\mathbf{E}$, has a non-Gaussian distribution and is concentrated in regions of high electric current density. Hence, magnetic energy is converted to kinetic energy in an intermittent manner. Furthermore, we find the higher-order statistics of magnetic field fluctuations generated by reconnection are characterized by multifractal scaling on magnetofluid scales and non-Gaussian global scale invariance on kinetic scales. These observations suggest $\\mathbf{J}\\cdot\\mathbf{E}$ within the reconnection jet has an analogue in fluid-like turbulence theory in that it proceeds via coherent structures generated by an intermittent cascade. This supports the hypothesis that turbulent dissipation is highly nonunifor...

  5. Composition PDF/photon Monte Carlo modeling of moderately sooting turbulent jet flames

    SciTech Connect (OSTI)

    Mehta, R.S.; Haworth, D.C.; Modest, M.F. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2010-05-15

    A comprehensive model for luminous turbulent flames is presented. The model features detailed chemistry, radiation and soot models and state-of-the-art closures for turbulence-chemistry interactions and turbulence-radiation interactions. A transported probability density function (PDF) method is used to capture the effects of turbulent fluctuations in composition and temperature. The PDF method is extended to include soot formation. Spectral gas and soot radiation is modeled using a (particle-based) photon Monte Carlo method coupled with the PDF method, thereby capturing both emission and absorption turbulence-radiation interactions. An important element of this work is that the gas-phase chemistry and soot models that have been thoroughly validated across a wide range of laminar flames are used in turbulent flame simulations without modification. Six turbulent jet flames are simulated with Reynolds numbers varying from 6700 to 15,000, two fuel types (pure ethylene, 90% methane-10% ethylene blend) and different oxygen concentrations in the oxidizer stream (from 21% O{sub 2} to 55% O{sub 2}). All simulations are carried out with a single set of physical and numerical parameters (model constants). Uniformly good agreement between measured and computed mean temperatures, mean soot volume fractions and (where available) radiative fluxes is found across all flames. This demonstrates that with the combination of a systematic approach and state-of-the-art physical models and numerical algorithms, it is possible to simulate a broad range of luminous turbulent flames with a single model. (author)

  6. Turbulent fluid jet excavation in cohesive soil : with particular application to jet grouting

    E-Print Network [OSTI]

    Ho, Chu Eu

    2005-01-01

    This thesis reviews the jet grouting methodology, and the current state of practice and research. Current methods of prediction of jet grout diameters are highly empirical and site specific, and do not take into account ...

  7. Numerical simulation of turbulent jet primary breakup in Diesel engines

    E-Print Network [OSTI]

    Helluy, Philippe

    Turbulence Mixture Fraction Spray mass coupling evaporation rate moment coupling mixing heat exchange Spray 2 Bernd Binninger1 Norbert Peters1 1 Institute for Combustion Technology RWTH-Aachen 2 Mechanical composition pollutant formation Combustion stability Need to accurately model Spray Process From injection

  8. Structure of turbulent hydrogen jet diffusion flames with or without swirl

    SciTech Connect (OSTI)

    Takahashi, Fumiaki; Vangsness, M.D.; Durbin, M.D.; Schmoll, W.J.

    1995-12-31

    The aerodynamic and thermal structure of double-concentric turbulent hydrogen jet diffusion flames with or without swirl has been investigated using three-component laser-Doppler velocimetry (LDV) and coherent anti-Stokes Raman spectroscopy. The LDV data were conditionally sampled upon the origin of the fluid (jet, annulus, or external) to avoid the velocity-bias problem and to gain more detailed information on the turbulent structure. As the mean jet velocity was increased, the turbulent flame zone shifted inward and the thermal layer became thinner, whereas swirl created a radial velocity even at the annulus air exit, thereby shifting the flame zone outward and broadening the thermal layer. The probability-density functions (pdf) of velocity components,m their 21 moments (up to fourth order), temperature pdf, mean, and root-mean-square fluctuation temperature were determined at numerous radial locations at seven axial heights in the near field (<26.5 jet diameters). The data can be used to validate computational models.

  9. TiO{sub 2} Film Deposition by Atmospheric Thermal Plasma CVD Using Laminar and Turbulence Plasma Jets

    SciTech Connect (OSTI)

    Ando, Yasutaka; Tobe, Shogo [Ashikaga Institute of Technology, 268-1 Omae, Ashikaga, Tochigi 326-8558 (Japan); Tahara, Hirokazu [Osaka Institute of Technology, 5-16-1 Omiya, Asahi-Ku, Osaka 535-8585 (Japan)

    2008-02-21

    In this study, to provide continuous plasma atmosphere on the substrate surface in the case of atmospheric thermal plasma CVD, TiO{sub 2} film deposition by thermal plasma CVD using laminar plasma jet was carried out. For comparison, the film deposition using turbulence plasma jet was conducted as well. Consequently, transition of the plasma jet from laminar to turbulent occurred on the condition of over 3.5 1/min in Ar working gas flow rate and the plasma jet became turbulent on the condition of over 10 1/min. In the case of the turbulent plasma jet use, anatase rich titanium oxide film could be obtained though plasma jet could not contact with the surface of the substrate continuously even on the condition that feedstock material was injected into the plasma jet. On the other hand,, in the case of laminar gas flow rate, the plasma jet could contact with the substrate continuously without melt down of the substrate during film deposition. Besides, titanium oxide film could be obtained even in the case of the laminar plasma jet use. From these results, this technique was thought to have high potential for atmospheric thermal plasma CVD.

  10. Investigation of Flame Stretch in Turbulent Lifted Jet Flame

    E-Print Network [OSTI]

    Ruan, S.; Swaminathan, N.; Mizobuchi, Y.

    2014-02-24

    jet flame, Mixed mode combustion, 2 1 Introduction The occurrence of mixed mode combustion in many practical devices such as strati- fied charge direct injection engines and lean burn gas turbine combustor is common. In these devices, typically fuel... ., 2009; Richardson et al., 2010; Chakraborty et al., 2010) and experimental (Hartung et al., 2008; Steinberg et al., 2012) studies of premixed combustion and stratified combustion (Malkeson and Chakraborty, 2011) have demonstrated that the reactive scalar...

  11. Large-scale eddies and their role in entrainment in turbulent jets and wakes Jimmy Philip and Ivan Marusic

    E-Print Network [OSTI]

    Marusic, Ivan

    Large-scale eddies and their role in entrainment in turbulent jets and wakes Jimmy Philip and Ivan. Fluids 24, 086101 (2012) The influence of large-scale structures on entrainment in a decelerating://pof.aip.org/about/rights_and_permissions #12;PHYSICS OF FLUIDS 24, 055108 (2012) Large-scale eddies and their role in entrainment in turbulent

  12. Understanding and predicting soot generation in turbulent non-premixed jet flames.

    SciTech Connect (OSTI)

    Wang, Hai; Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.

    2010-10-01

    This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically-thick radiation model to accurately predict gas temperatures and thus soot formation rates. When including such a radiation model, the LES model predicts mean soot concentrations within 30% in the ethylene jet flame.

  13. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore »the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  14. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane air jet flames

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore »the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  15. Relation Between Type-II ELMs, Edge Localized Turbulence, Washboard Modes and Energy Losses Between ELMs in High Density ELMy H-modes on JET

    E-Print Network [OSTI]

    Relation Between Type-II ELMs, Edge Localized Turbulence, Washboard Modes and Energy Losses Between ELMs in High Density ELMy H-modes on JET

  16. Probability density function treatment of turbulence/chemistry interactions during the ignition of a temperature-stratified mixture for application to HCCI engine modeling

    SciTech Connect (OSTI)

    Bisetti, Fabrizio; Chen, J.-Y.; Hawkes, Evatt R.; Chen, Jacqueline H.

    2008-12-15

    Homogeneous charge compression ignition (HCCI) engine technology promises to reduce NO{sub x} and soot emissions while achieving high thermal efficiency. Temperature and mixture stratification are regarded as effective means of controlling the start of combustion and reducing the abrupt pressure rise at high loads. Probability density function methods are currently being pursued as a viable approach to modeling the effects of turbulent mixing and mixture stratification on HCCI ignition. In this paper we present an assessment of the merits of three widely used mixing models in reproducing the moments of reactive scalars during the ignition of a lean hydrogen/air mixture ({phi}=0.1, p=41atm, and T=1070 K) under increasing temperature stratification and subject to decaying turbulence. The results from the solution of the evolution equation for a spatially homogeneous joint PDF of the reactive scalars are compared with available direct numerical simulation (DNS) data [E.R. Hawkes, R. Sankaran, P.P. Pebay, J.H. Chen, Combust. Flame 145 (1-2) (2006) 145-159]. The mixing models are found able to quantitatively reproduce the time history of the heat release rate, first and second moments of temperature, and hydroxyl radical mass fraction from the DNS results. Most importantly, the dependence of the heat release rate on the extent of the initial temperature stratification in the charge is also well captured. (author)

  17. Diffusive radiation in Langmuir turbulence produced by jet shocks

    E-Print Network [OSTI]

    Gregory D. Fleishman; Igor N. Toptygin

    2007-06-03

    Anisotropic distributions of charged particles including two-stream distributions give rise to generation of either stochastic electric fields (in the form of Langmuir waves, Buneman instability) or random quasi-static magnetic fields (Weibel and filamentation instabilities) or both. These two-stream instabilities are known to play a key role in collisionless shock formation, shock-shock interactions, and shock-induced electromagnetic emission. This paper applies the general non-perturbative stochastic theory of radiation to study electromagnetic emission produced by relativistic particles, which random walk in the stochastic electric fields of the Langmuir waves. This analysis takes into account the cumulative effect of uncorrelated Langmuir waves on the radiating particle trajectory giving rise to angular diffusion of the particle, which eventually modifies the corresponding radiation spectra. We demonstrate that the radiative process considered is probably relevant for emission produced in various kinds of astrophysical jets, in particular, prompt gamma-ray burst spectra, including X-ray excesses and prompt optical flashes.

  18. Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames

    SciTech Connect (OSTI)

    Weiland, N.T.; Strakey, P.A.

    2007-03-01

    Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Program’s aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter nitrogen dilution and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2 4 and 8 atm. The NOx emission data from these experiments are discussed as well as the results from a Computational Fluid Dynamics modeling effort currently underway to help explain the experimental data.

  19. Triple cascade behaviour in QG and drift turbulence and generation of zonal jets

    E-Print Network [OSTI]

    Sergey Nazarenko; Brenda Quinn

    2009-05-08

    We study quasi-geostrophic turbulence and plasma drift turbulence within the Charney-Hasegawa-Mima (CHM) model. We focus, theoretically and using numerical simulations, on conservation of {\\em zonostrophy} and on its role in the formation of the zonal jets. The zonostrophy invariant was first predicted in \\cite{perm,BNZ_invariant} in two special cases -- large-scale turbulence and anisotropic turbulence. Papers \\cite{perm,BNZ_invariant} also predicted that the three invariants, energy, enstrophy and zonostrophy, will cascade anisotropically into non-intersecting sectors in the $k$-space, so that the energy cascade is "pushed" into the large-scale zonal scales. In the present paper, we consider the scales much less than the Rossby deformation radius and generalise the Fj{\\o}rtoft argument of \\cite{perm,BNZ_invariant} to find the directions of the three cascades in this case. For the first time, we demonstrate numerically that zonostrophy is well conserved by the CHM model, and that the energy, enstrophy and zonostrophy cascade as prescribed by the Fj{\\o}rtoft argument if the nonlinearity is sufficiently weak. Moreover, numerically we observe that zonostrophy is conserved surprisingly well at late times and the triple-cascade picture is rather accurate even if the initial nonlinearity is strong.

  20. The application of complex network time series analysis in turbulent heated jets

    SciTech Connect (OSTI)

    Charakopoulos, A. K.; Karakasidis, T. E. Liakopoulos, A.; Papanicolaou, P. N.

    2014-06-15

    In the present study, we applied the methodology of the complex network-based time series analysis to experimental temperature time series from a vertical turbulent heated jet. More specifically, we approach the hydrodynamic problem of discriminating time series corresponding to various regions relative to the jet axis, i.e., time series corresponding to regions that are close to the jet axis from time series originating at regions with a different dynamical regime based on the constructed network properties. Applying the transformation phase space method (k nearest neighbors) and also the visibility algorithm, we transformed time series into networks and evaluated the topological properties of the networks such as degree distribution, average path length, diameter, modularity, and clustering coefficient. The results show that the complex network approach allows distinguishing, identifying, and exploring in detail various dynamical regions of the jet flow, and associate it to the corresponding physical behavior. In addition, in order to reject the hypothesis that the studied networks originate from a stochastic process, we generated random network and we compared their statistical properties with that originating from the experimental data. As far as the efficiency of the two methods for network construction is concerned, we conclude that both methodologies lead to network properties that present almost the same qualitative behavior and allow us to reveal the underlying system dynamics.

  1. Statistical analysis of the velocity and scalar fields in reacting turbulent wall-jets

    E-Print Network [OSTI]

    Pouransari, Z; Johansson, A V

    2015-01-01

    The concept of local isotropy in a chemically reacting turbulent wall-jet flow is addressed using direct numerical simulation (DNS) data. Different DNS databases with isothermal and exothermic reactions are examined. The chemical reaction and heat release effects on the turbulent velocity, passive scalar and reactive species fields are studied using their probability density functions (PDF) and higher order moments for velocities and scalar fields, as well as their gradients. With the aid of the anisotropy invariant maps for the Reynolds stress tensor the heat release effects on the anisotropy level at different wall-normal locations are evaluated and found to be most accentuated in the near-wall region. It is observed that the small-scale anisotropies are persistent both in the near-wall region and inside the jet flame. Two exothermic cases with different Damkohler number are examined and the comparison revealed that the Damkohler number effects are most dominant in the near-wall region, where the wall cooli...

  2. Statistical analysis of the velocity and scalar fields in reacting turbulent wall-jets

    E-Print Network [OSTI]

    Z. Pouransari; L. Biferale; A. V. Johansson

    2015-02-21

    The concept of local isotropy in a chemically reacting turbulent wall-jet flow is addressed using direct numerical simulation (DNS) data. Different DNS databases with isothermal and exothermic reactions are examined. The chemical reaction and heat release effects on the turbulent velocity, passive scalar and reactive species fields are studied using their probability density functions (PDF) and higher order moments for velocities and scalar fields, as well as their gradients. With the aid of the anisotropy invariant maps for the Reynolds stress tensor the heat release effects on the anisotropy level at different wall-normal locations are evaluated and found to be most accentuated in the near-wall region. It is observed that the small-scale anisotropies are persistent both in the near-wall region and inside the jet flame. Two exothermic cases with different Damkohler number are examined and the comparison revealed that the Damkohler number effects are most dominant in the near-wall region, where the wall cooling effects are influential. In addition, with the aid of PDFs conditioned on the mixture fraction, the significance of the reactive scalar characteristics in the reaction zone is illustrated. We argue that the combined effects of strong intermittency and strong persistency of anisotropy at the small scales in the entire domain can affect mixing and ultimately the combustion characteristics of the reacting flow.

  3. Jet plume injection and combustion system for internal combustion engines

    DOE Patents [OSTI]

    Oppenheim, Antoni K. (Kensington, CA); Maxson, James A. (Berkeley, CA); Hensinger, David M. (Albany, CA)

    1993-01-01

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure.

  4. Jet plume injection and combustion system for internal combustion engines

    DOE Patents [OSTI]

    Oppenheim, A.K.; Maxson, J.A.; Hensinger, D.M.

    1993-12-21

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure. 24 figures.

  5. HPC realization of a controlled turbulent round jet using OpenFOAM

    E-Print Network [OSTI]

    Önder, Asim

    2014-01-01

    The present paper investigates high performance computing abilities of OpenFOAM for a low Reynolds number ($Re_D=2000$) axisymmetric jet subject to multiple zero net mass flux (ZNMF) actuators. First, parallel performance of OpenFOAM is tested by performing a scaling study up to $2048$ processors on a supercomputer of Flemish Supercomputer Center(VSC). Then, a method to improve the parallel efficiency is proposed. The method is based on developing a hybrid concept to calculate the statistical moments. This new concept combines ensemble and time averaging in order to allow data sampling in parallel. The motivation is obtaining a reduction in the walltime to collect turbulent statistics which is observed to be the dominating part in the ZNMF controlled jet flow. Employing this parallel statistical averaging approach in combination with regular grid partitioning parallelism, allowed us conducting DNS cases on $P=624$ processors with an overall speed-up of $S_e=540.56$ and a parallel efficiency of $E_e=0.87$. The...

  6. The effect of turbulence on the stability of liquid jets and the resulting droplet size distributions. Third quarterly technical report, July 1, 1993--September 30, 1993

    SciTech Connect (OSTI)

    Mansour, A.; Chigier, N.

    1993-12-01

    Laminar and turbulent columns of liquids issuing from capillary tubes were studied in order to determine the effects of turbulence on the stability of liquid jets and to establish the influence of liquid turbulence on droplet size distributions after breakup. Two capillary tubes were chosen with diameters D{sub 1}=3.0mm and D{sub 2}=1.2mm; jet Reynolds numbers were 1000--30000, and 400--7200. For water injection into stagnant air, stability curve is bounded by a laminar portion, where a jet radius and {delta}{sub o} initial disturbance amplitude, and a fully developed turbulent portion characterized by high initial disturbance amplitude (ln(a/{delta}{sub o,T}) {approximately} 4.85). In the transition region, ln(a/{delta}{sub o}) is not single valued; it decreases with increasing Reynolds number. In absence of aerodynamic effects, turbulent jets are as stable as laminar jets. For this breakup mode turbulence propagates initial disturbances with amplitudes orders of magnitude larger than laminar jets ({delta}{sub o,T}=28{times}10{sup 6} {delta}{sub o,L}). Growth rates of initial disturbances are same for both laminar and turbulent columns with theoretical Weber values. Droplet size distribution is bi-modal; the number ratio of large (> D/2), to small (< D/2) droplets is 3 and independent of Reynolds number. For laminar flow optimum wavelength ({lambda}{sub opt}) corresponding to fastest growing disturbance is equal to 4.45D, exactly the theoretical Weber value. For turbulent flow conditions, the turbulent column segments. Typically, segments with lengths of one to several wavelengths, detach from the liquid jet. The long ligaments contract under the action of surface tension, resulting in droplet sizes larger than predicted by Rayleigh and Weber. For turbulent flow conditions, {lambda}{sub opt} = 9.2D, about 2 times the optimum Weber wavelength.

  7. An Analysis of Self-similarity, Momentum Conservation and Energy Transport for an Axisymmetric Turbulent Jet through a Staggered Array of Rigid Emergent Vegetation 

    E-Print Network [OSTI]

    Allen, Jon Scott

    2013-05-29

    as storm protection using an ADV measurement technique, and is the first to apply jet self-similarity analysis to characterize the overall mean and turbulent flow properties of a three-dimensional axisymmetric jet through a vegetated array. The mean axial...

  8. Advanced CFD Models for High Efficiency Compression Ignition Engines

    Broader source: Energy.gov [DOE]

    Advanced CFD models for high efficiency compression-ignition engines can be used to show how turbulence-chemistry interactions influence autoignition and combustion.

  9. Advanced CFD Models for High Efficiency Compression Ignition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    for high efficiency compression-ignition engines can be used to show how turbulence-chemistry interactions influence autoignition and combustion. p-19raja.pdf More Documents &...

  10. Simultaneous imaging of OH, formaldehyde, and temperature of turbulent nonpremixed jet flames in a heated and diluted coflow

    SciTech Connect (OSTI)

    Medwell, Paul R.; Kalt, Peter A.M.; Dally, Bassam B. [School of Mechanical Engineering, The University of Adelaide, S.A. 5005 (Australia)

    2007-01-15

    This paper reports measurements in turbulent nonpremixed CH{sub 4}/H{sub 2} jet flames issuing into a heated and highly diluted coflow. These conditions emulate those of moderate or intense low-oxygen-dilution (MILD) combustion. The spatial distribution of the hydroxyl radical (OH), formaldehyde (H{sub 2}CO), and temperature, imaged using planar laser-induced fluorescence and Rayleigh scattering laser diagnostic techniques, are measured and presented. Comparisons are made between three jet Reynolds numbers and two coflow O{sub 2} levels. Measurements are taken at two downstream locations. The burner used in this work facilitates the additional study on the effects of the entrainment of surrounding air on the flame structure at downstream locations. Reducing the coflow oxygen level is shown to lead to a suppression of OH as a result of the reduced temperatures in the reaction zone. Decreasing the oxygen level of the coflow also results in a broadening of the OH distribution. At downstream locations, the surrounding air mixes with the jet and coflow. The subsequent drop in the temperature of the oxidant stream can lead to a rupture of the OH layer. Localized extinction allows premixing of the fuel with the surrounding air. The result is an increase in the reaction rate, highlighting the need for homogeneous mixing to maintain MILD combustion conditions. (author)

  11. ENHANCED IGNITION FOR I.C. ENGINES WITH PREMIXED CHARGE

    E-Print Network [OSTI]

    Dale, J.D.

    2013-01-01

    Turkish, M. C. "3-Valve Stratified Charge Engines: Analysis741163, Evolvement, Stratified_ Charge Engines, I. Mech. E.Sonic Jet Ignition --A Stratified Charge Concept," Physics

  12. Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown

    E-Print Network [OSTI]

    Heinz, Stefan

    simulation method to studies of the mechanism of swirl effects shows the following. Swirl breaks apart, n i 2 N0; 1 = kinematic viscosity T = Reynolds-averaged Navier­Stokes turbulent viscosity

  13. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry: Spray Simulations

    SciTech Connect (OSTI)

    Rutland, Christopher J.

    2009-04-26

    The Terascale High-Fidelity Simulations of Turbulent Combustion (TSTC) project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of the approach is direct numerical simulation (DNS) featuring the highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. Under this component of the TSTC program the simulation code named S3D, developed and shared with coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for turbulent liquid fuel spray dynamics. Major accomplishments include improved fundamental understanding of mixing and auto-ignition in multi-phase turbulent reactant mixtures and turbulent fuel injection spray jets.

  14. Particle dispersion within zonal jets in two-layer beta-plane turbulence 

    E-Print Network [OSTI]

    Roman, Jennifer Claire

    1996-01-01

    Passive tracer dispersion is studied in a two-layer, quasigeostrophic, betaplane model in which persistent, steady, zonal jets are observed. Particle trajectories and statistics are examined for barriers to or mechanisms for mixing. Simulations...

  15. Three dimensional analysis of turbulent steam jets in enclosed structures : a CFD approach.

    SciTech Connect (OSTI)

    Ishii, M.; NguyenLe, Q.

    1999-04-20

    This paper compares the three-dimensional numerical simulation with the experimental data of a steam blowdown event in a light water reactor containment building. The temperature and pressure data of a steam blowdown event was measured at the Purdue University Multi-Dimensional Integrated Test Assembly (PUMA), a scaled model of the General Electric simplified Boiling Water Reactor. A three step approach was used to analyze the steam jet behavior. First, a 1-Dimensional, system level RELAP5/Mod3.2 model of the steam blowdown event was created and the results used to set the initial conditions for the PUMA blowdown experiments. Second, 2-Dimensional CFD models of the discharged steam jets were computed using PHOENICS, a commercially available CFD package. Finally, 3-Dimensional model of the PUMA drywell was created with the boundary conditions based on experimental measurements. The results of the 1-D and 2-D models were reported in the previous meeting. This paper discusses in detail the formulation and the results of the 3-Dimensional PHOENICS model of the PUMA drywell. It is found that the 3-D CFD solutions compared extremely well with the measured data.

  16. Numerical Simulations of Boiling Jet Impingement Cooling in Power Electronics

    SciTech Connect (OSTI)

    Narumanchi, S.; Troshko, A.; Hassani, V.; Bharathan, D.

    2006-12-01

    This paper explores turbulent boiling jet impingement for cooling power electronic components in hybrid electric vehicles.

  17. Laser ignition

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    2003-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In a third embodiment, alternating short and long pulses of light from the excitation light source are directed into the ignitor laser. Each of the embodiments of the invention can be multiplexed so as to provide laser light energy sequentially to more than one ignitor laser.

  18. Terascale Direct Numerical Simulations of Turbulent Combustion: Capabilities and Limits (PReSS Talk)

    SciTech Connect (OSTI)

    Yoo, Chun Sang

    2009-03-26

    The rapid growth in computational capabilities has provided great opportunities for direct numerical simulations (DNS) of turbulent combustion, a type of simulations without any turbulence model. With the help of terascale high performance supercomputing (HPC) resources, we are now able to provide fundamental insight into turbulence-chemistry interaction in simple laboratory-scale turbulent flames with detailed chemistry using three-dimensional (3D) DNS. However, the actual domain size of 3D-DNS is still limited within {approx} O(10 cm{sup 3}) due to its tremendously high grid resolution required to resolve the smallest turbulent length scale as well as flame structures. Moreover, 3D-DNS will require more computing powers to investigate next-generation engines, of which operating conditions will be characterized by higher pressures, lower temperatures, and higher levels of dilution. In this talk, I will discuss the capabilities and limits of DNS of turbulent combustion and present some results of ignition/extinction characteristics of a highly diluted hydrogen flame counter-flowing against heated air. The results of our recent 3D-DNS of a spatially-developing turbulent lifted hydrogen jet flame in heated coflow will also be presented. The 3D-DNS was performed at a jet Reynolds number of 11,000 with {approx} 1 billion grid points, which required 3.5 million CPU hours on Cray XT3/XT4 at Oak Ridge National Laboratories.

  19. Advanced ignition and propulsion technology program

    SciTech Connect (OSTI)

    Oldenborg, R.; Early, J.; Lester, C.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Reliable engine re-ignition plays a crucial role in enabling commercial and military aircraft to fly safely at high altitudes. This project addressed research elements critical to the optimization of laser-based igniter. The effort initially involved a collaborative research and development agreement with B.F. Goodrich Aerospace and Laser Fare, Inc. The work involved integrated experiments with theoretical modeling to provide a basic understanding of the chemistry and physics controlling the laser-induced ignition of fuel aerosols produced by turbojet engine injectors. In addition, the authors defined advanced laser igniter configurations that minimize laser packaging size, weight, complexity and power consumption. These innovative ignition concepts were shown to reliably ignite jet fuel aerosols over a broad range of fuel/air mixture and a t fuel temperatures as low as -40 deg F. The demonstrated fuel ignition performance was highly superior to that obtained by the state-of-the-art, laser-spark ignition method utilizing comparable laser energy. The authors also developed a laser-based method that effectively removes optically opaque deposits of fuel hydrocarbon combustion residues from laser window surfaces. Seven patents have been either issued or are pending that resulted from the technology developments within this project.

  20. Experimental study of turbulent flame kernel propagation

    SciTech Connect (OSTI)

    Mansour, Mohy [National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt); Peters, Norbert; Schrader, Lars-Uve [Institute of Combustion Technology, Aachen (Germany)

    2008-07-15

    Flame kernels in spark ignited combustion systems dominate the flame propagation and combustion stability and performance. They are likely controlled by the spark energy, flow field and mixing field. The aim of the present work is to experimentally investigate the structure and propagation of the flame kernel in turbulent premixed methane flow using advanced laser-based techniques. The spark is generated using pulsed Nd:YAG laser with 20 mJ pulse energy in order to avoid the effect of the electrodes on the flame kernel structure and the variation of spark energy from shot-to-shot. Four flames have been investigated at equivalence ratios, {phi}{sub j}, of 0.8 and 1.0 and jet velocities, U{sub j}, of 6 and 12 m/s. A combined two-dimensional Rayleigh and LIPF-OH technique has been applied. The flame kernel structure has been collected at several time intervals from the laser ignition between 10 {mu}s and 2 ms. The data show that the flame kernel structure starts with spherical shape and changes gradually to peanut-like, then to mushroom-like and finally disturbed by the turbulence. The mushroom-like structure lasts longer in the stoichiometric and slower jet velocity. The growth rate of the average flame kernel radius is divided into two linear relations; the first one during the first 100 {mu}s is almost three times faster than that at the later stage between 100 and 2000 {mu}s. The flame propagation is slightly faster in leaner flames. The trends of the flame propagation, flame radius, flame cross-sectional area and mean flame temperature are related to the jet velocity and equivalence ratio. The relations obtained in the present work allow the prediction of any of these parameters at different conditions. (author)

  1. Enhanced ignition for I. C. engines with premixed gases

    SciTech Connect (OSTI)

    Dale, J.D.; Oppenheim, A.K.

    1981-01-01

    The development of lean charge, fast burn engines depends crucially on enhanced ignition. Enhanced ignition involves not only high energies and long duration of ignition, but also a wide dispersion of its sources, so that combustion is carried out at as many sites throughout the charge as possible. Upon this premise, various ignition systems for I.C. engines, operating with premixed charge, are reviewed. The systems are grouped as follows: high energy spark plugs; plasma jet igniters; photochemical, laser, and microwave ignition concepts; torch cells; divided chamber stratified charge engines; flame jet igniters; combustion jet ignition concepts; EGR ignition system. The first three derive the power from electrical energy, the rest are powered by exothermic chemical reactions. The review emphasizes the concept of staging the processes of initiation and propagation of combustion. Relative positions of various ignition systems are expressed on the plane of relative energies (the ratio of energy consumed by the ignition system, or contained in a pre-chamber, to that of the compressed charge in the main chamber) and relative volumes (the ratio of the volume of the pre-chamber to that of the compressed charge). In principle, ignition systems for engines operating with premixed charge lie on the half-plane of relative energies below one, between 10/sup -5/ for standard spark plugs to 10/sup -1/ for divided chamber stratified charge engines, while their relative volumes extend from 0 for spark igniters to 0.2 for stratified charge engines. This suggests that proper compartmentization of the combustion process may lead to significant improvements in both pollution emissions from the cylinder and specific fuel consumption of I.C. engines.

  2. Sandia Energy - The CRF's Turbulent Combustion Lab (TCL) Captures...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CRF's Turbulent Combustion Lab (TCL) Captures the Moment of Hydrogen Ignition Home Energy Transportation Energy CRF Facilities News News & Events Research & Capabilities The CRF's...

  3. An analytical investigation of primary zone combustion temperatures and NOx production for turbulent jet flames using low-BTU fuels 

    E-Print Network [OSTI]

    Carney, Christopher Mark

    1995-01-01

    The objective of this research project was to identify and determine the effect of jet burner operating variables that influence combustion of low-BTU gases. This was done by simulating the combustion of a low-BTU fuel in a jet flame and predicting...

  4. Laser ignition

    DOE Patents [OSTI]

    Early, James W.; Lester, Charles S.

    2004-01-13

    Sequenced pulses of light from an excitation laser with at least two resonator cavities with separate output couplers are directed through a light modulator and a first polarzing analyzer. A portion of the light not rejected by the first polarizing analyzer is transported through a first optical fiber into a first ignitor laser rod in an ignitor laser. Another portion of the light is rejected by the first polarizing analyzer and directed through a halfwave plate into a second polarization analyzer. A first portion of the output of the second polarization analyzer passes through the second polarization analyzer to a second, oscillator, laser rod in the ignitor laser. A second portion of the output of the second polarization analyzer is redirected by the second polarization analyzer to a second optical fiber which delays the beam before the beam is combined with output of the first ignitor laser rod. Output of the second laser rod in the ignitor laser is directed into the first ignitor laser rod which was energized by light passing through the first polarizing analyzer. Combined output of the first ignitor laser rod and output of the second optical fiber is focused into a combustible fuel where the first short duration, high peak power pulse from the ignitor laser ignites the fuel and the second long duration, low peak power pulse directly from the excitation laser sustains the combustion.

  5. Enhanced ignition for I. C. engines with premixed charge

    SciTech Connect (OSTI)

    Dale, J.D.; Oppenheim, A.K.

    1980-10-01

    The development of lean charge, fast burn engines depends crucially on enhanced ignition, since one can obtain thereby proper means for increasing the rate of burn in mixtures characterized notoriously by low normal burning speeds. Enhanced ignition involves a wide dispersion of its sources so that combustion is carried out at as many sites throughout the charge as possible. Upon this premise, various ignition systems for I.C. engines, operating with premixed charge, are reviewed. The systems are grouped within the following categories: (1) high energy spark plugs; (2) plasma jet igniters; (3) photochemical, laser, and microwave ignition concepts; (4) torch cells; (5) divided chamber stratified charge engines; (6) flame jet igniters; (7) combustion jet ignition concepts; (8) EGR ignition system. The first three derive the power from electrical energy, the rest are powered by exothermic chemical reactions at a significantly lower, practically negligible, fuel consumption. The concept of staging the processes of initiation and propagation of combustion is emphasized. Relative positions of various ignition systems are expressed on the plane of relative energies and relative volumes. In principle, ignition systems for engines operating with premixed charge lie on the half-plane of relative energies below one, between 10/sup -5/ for standard spark plugs to 10/sup -1/ for divided chamber stratified charge engines, while their relative volumes extend from 0 for spark igniters to 0.2 for stratified charge engines. This suggests that proper compartmentization of the combustion process may lead to significant improvements in both pollution emissions from the cylinder and specific fuel consumption of I.C. engines.

  6. Laser preheat enhanced ignition

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM)

    1999-01-01

    A method for enhancing fuel ignition performance by preheating the fuel with laser light at a wavelength that is absorbable by the fuel prior to ignition with a second laser is provided.

  7. Laser preheat enhanced ignition

    DOE Patents [OSTI]

    Early, J.W.

    1999-03-02

    A method for enhancing fuel ignition performance by preheating the fuel with laser light at a wavelength that is absorbable by the fuel prior to ignition with a second laser is provided. 11 figs.

  8. Turbulent combustion

    SciTech Connect (OSTI)

    Talbot, L.; Cheng, R.K. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  9. Turbulence and combustion interaction: High resolution local flame front structure visualization using simultaneous single-shot PLIF imaging of CH, OH, and CH{sub 2}O in a piloted premixed jet flame

    SciTech Connect (OSTI)

    Li, Z.S.; Li, B.; Sun, Z.W.; Alden, M. [Division of Combustion Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Bai, X.S. [Division of Fluid Mechanics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)

    2010-06-15

    High resolution planar laser-induced fluorescence (PLIF) was applied to investigate the local flame front structures of turbulent premixed methane/air jet flames in order to reveal details about turbulence and flame interaction. The targeted turbulent flames were generated on a specially designed coaxial jet burner, in which low speed stoichiometric gas mixture was fed through the outer large tube to provide a laminar pilot flame for stabilization of the high speed jet flame issued through the small inner tube. By varying the inner tube flow speed and keeping the mixture composition as that of the outer tube, different flames were obtained covering both the laminar and turbulent flame regimes with different turbulent intensities. Simultaneous CH/CH{sub 2}O, and also OH PLIF images were recorded to characterize the influence of turbulence eddies on the reaction zone structure, with a spatial resolution of about 40 {mu}m and temporal resolution of around 10 ns. Under all experimental conditions, the CH radicals were found to exist only in a thin layer; the CH{sub 2}O were found in the inner flame whereas the OH radicals were seen in the outer flame with the thin CH layer separating the OH and CH{sub 2}O layers. The outer OH layer is thick and it corresponds to the oxidation zone and post-flame zone; the CH{sub 2}O layer is thin in laminar flows; it becomes broad at high speed turbulent flow conditions. This phenomenon was analyzed using chemical kinetic calculations and eddy/flame interaction theory. It appears that under high turbulence intensity conditions, the small eddies in the preheat zone can transport species such as CH{sub 2}O from the reaction zones to the preheat zone. The CH{sub 2}O species are not consumed in the preheat zone due to the absence of H, O, and OH radicals by which CH{sub 2}O is to be oxidized. The CH radicals cannot exist in the preheat zone due to the rapid reactions of this species with O{sub 2} and CO{sub 2} in the inner-layer of the reaction zones. The local PLIF intensities were evaluated using an area integrated PLIF signal. Substantial increase of the CH{sub 2}O signal and decrease of CH signal was observed as the jet velocity increases. These observations raise new challenges to the current flamelet type models. (author)

  10. Thermal ignition combustion system

    DOE Patents [OSTI]

    Kamo, Roy (Columbus, IN); Kakwani, Ramesh M. (Columbus, IN); Valdmanis, Edgars (Columbus, IN); Woods, Melvins E. (Columbus, IN)

    1988-01-01

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m.degree. C. and a specific heat greater than 480 J/kg.degree. C. with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber.

  11. Thermal ignition combustion system

    DOE Patents [OSTI]

    Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

    1988-04-19

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

  12. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    SciTech Connect (OSTI)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O'Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  13. Low profile thermite igniter

    DOE Patents [OSTI]

    Halcomb, Danny L. (Camden, OH); Mohler, Jonathan H. (Spring Valley, OH)

    1991-03-05

    A thermite igniter/heat source comprising a housing, high-density thermite, and low-density thermite. The housing has a relatively low profile and can focus energy by means of a torch-like ejection of hot reaction products and is externally ignitable.

  14. PERFORMANCE OF A PLASMA JET IGNITER

    E-Print Network [OSTI]

    Cetegen, B.

    2013-01-01

    of divided-chamber stratified charge engines where theM.C.Turkish, "3-Valve Stratified Charge 0.6 are in the rangeM.C.Turkish, "3-Valve Stratified Charge Engines: Evolvement,

  15. Jet Streams Jet Streams

    E-Print Network [OSTI]

    Hennon, Christopher C.

    ATMS 310 Jet Streams Jet Streams A jet stream is an intense (30+ m/s in upper troposphere, 15+ m of air associated with strong (at least 5-10 ms-1 km-1 ) vertical wind shear. A Jet Streak is an isotach maximum embedded within a jet stream. Jet streams are mesoscale in the cross-flow direction and synoptic

  16. National Ignition Facility & Photon Science What

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ignition Facility & Photon Science What is NiF? the national ignition Facility: bringing star Power to earth The National Ignition Facility (NIF) is the world's largest and...

  17. Jets with Reversing Buoyancy

    E-Print Network [OSTI]

    Pandya, R V R

    2015-01-01

    A jet of heavy fluid is injected upwards, at time $t=0$, into a lighter fluid and reaches a maximum height at time $t=t_i$ and then flows back around the upward flow. A similar flow situation occurs for a light fluid injected downward into a heavy one. In this paper an exact analytical expression for $t_i$ is derived. The expression remains valid for laminar and turbulent buoyant jets with or without swirl.

  18. Under consideration for publication in J. Fluid Mech. 1 Emergence and equilibration of jets in

    E-Print Network [OSTI]

    Farrell, Brian F.

    Under consideration for publication in J. Fluid Mech. 1 Emergence and equilibration of jets in beta scale jets that are not forced directly at the jet scale are a prominent feature of rotating turbulence. These jets arise and are supported by systematic orga- nization of the turbulent Reynolds stresses

  19. Features of a point design for fast ignition

    SciTech Connect (OSTI)

    Tabak, M; Clark, D; Town, R J; Key, M H; Amendt, P; Ho, D; Meeker, D J; Shay, H D; Lasinski, B F; Kemp, A; Divol, L; Mackinnon, A J; Patel, P; Strozzi, D; Grote, D P

    2009-10-26

    Fast Ignition is an inertial fusion scheme in which fuel is first assembled and then heated to the ignition temperature with an external heating source. In this note we consider cone and shell implosions where the energy supplied by short pulse lasers is transported to the fuel by electrons. We describe possible failure modes for this scheme and how to overcome them. In particular, we describe two sources of cone tip failure, an axis jet driven from the compressed fuel mass and hard photon preheat leaking through the implosion shell, and laser prepulse that can change the position of laser absorption and the angular distribution of the emitted electrons.

  20. On zonal jets in oceans Balasubramanya T. Nadiga1

    E-Print Network [OSTI]

    Nadiga, Balasubramanya T. "Balu"

    On zonal jets in oceans Balasubramanya T. Nadiga1 Received 26 January 2006; revised 29 March 2006 to the recently observed alternating zonal jets in oceans, the formation of these jets can be explained as due of alternating jets in Jovian atmospheres and two dimensional turbulence in zonally-periodic configurations

  1. AIAA Paper 2006-0102 Analysis of Jet Effects on Co-Flow Jet Airfoil

    E-Print Network [OSTI]

    Zha, Gecheng

    engine inlet j jet injection Freestream Greek Letters: Turbulent Dissipation Rate Ratio of SpecificAIAA Paper 2006-0102 Analysis of Jet Effects on Co-Flow Jet Airfoil Performance with Integrated Propulsion System Ge-Cheng Zha and Wei Gao Dept. of Mechanical and Aerospace Engineering University of Miami

  2. Burner ignition system

    DOE Patents [OSTI]

    Carignan, Forest J. (Bedford, MA)

    1986-01-21

    An electronic ignition system for a gas burner is battery operated. The battery voltage is applied through a DC-DC chopper to a step-up transformer to charge a capacitor which provides the ignition spark. The step-up transformer has a significant leakage reactance in order to limit current flow from the battery during initial charging of the capacitor. A tank circuit at the input of the transformer returns magnetizing current resulting from the leakage reactance to the primary in succeeding cycles. An SCR in the output circuit is gated through a voltage divider which senses current flow through a flame. Once the flame is sensed, further sparks are precluded. The same flame sensor enables a thermopile driven main valve actuating circuit. A safety valve in series with the main gas valve responds to a control pressure thermostatically applied through a diaphragm. The valve closes after a predetermined delay determined by a time delay orifice if the pilot gas is not ignited.

  3. Center for Turbulence Research Annual Research Briefs 2008

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    in a supersonic turbulent crossflow By S. Kawai AND S. K. Lele 1. Motivation and objectives Important recent load, etc. Jet mixing in a supersonic crossflow (JISC) is a type of flow where compressible LES can, the enhancement of supersonic turbulent mixing of jet fuel and crossflow air is a critical issue in developing

  4. Ignition dynamics of high explosives

    SciTech Connect (OSTI)

    Ali, A.N.; Son, S.F.; Sander, R.K.; Asay, B.W.; Brewster, M.Q.

    1999-04-01

    The laser ignition of the explosives HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, C{sub 4}H{sub 8}N{sub 8}O{sub 8}), {delta}-phase HMX, PBX 9501 (95% HMX, 2.5% Estane, 2.5% BDNPA/BDNPF), TATB (1,3,5-triamino-2,4,6-trinitrobenzene, C{sub 6}H{sub 6}N{sub 6}O{sub 6}), and PBX 9502 (95% TATB, 5% Kel-F) and aged PBX 9502 has been conducted with the intent to compare the relative sensitivities of those explosives and to investigate the effect of beam profile, binder addition, and porosity. It has been found that there was little difference between a gaussian beam and a top hat profile on the laser ignition of HMX. The authors observe that the addition of binder in the amounts present in PBX 9501 resulted in longer ignition delays than that of HMX. In contrast to HMX, the addition of binder to TATB in PBX 9502 shows no measurable effect. Porosity effects were considered by comparing the ignition of granular HMX and pressed HMX pellets. Porosity appears to increase ignition delay due to an increased effective absorption scale and increased convective heat loss. This porosity effect also resulted in longer ignition delays for {delta}-phase HMX than for {beta}-phase HMX. In order to simulate ignition in voids or cracks, the standard ignition experiment was modified to include a NaCl window placed at variable distances above the sample surface. When ignition experiments were performed at 29 W/cm{sup 2} and 38 W/cm{sup 2} a critical gap distance was observed of 6 {+-} 0.4 mm below which ignition was severely inhibited. This result underscores the importance of gas phase processes in ignition and illustrates that conditions can exist where simple ignition criteria such as surface temperature is inadequate.

  5. National Ignition Facility & Photon Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    security maintaining the nuclear weapons stockpile As the largest, highest-energy laser ever built, the National Ignition Facility (NIF) can create conditions in the...

  6. Ignition and Inertial Confinement Fusion at The National Ignition Facility

    SciTech Connect (OSTI)

    Moses, E

    2009-10-01

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear burn in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm{sup 3}-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIF's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY2010 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

  7. Turbulent burning rates of methane and methane-hydrogen mixtures

    SciTech Connect (OSTI)

    Fairweather, M. [School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Ormsby, M.P.; Sheppard, C.G.W. [School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Woolley, R. [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2009-04-15

    Methane and methane-hydrogen (10%, 20% and 50% hydrogen by volume) mixtures have been ignited in a fan stirred bomb in turbulence and filmed using high speed cine schlieren imaging. Measurements were performed at 0.1 MPa (absolute) and 360 K. A turbulent burning velocity was determined for a range of turbulence velocities and equivalence ratios. Experimental laminar burning velocities and Markstein numbers were also derived. For all fuels the turbulent burning velocity increased with turbulence velocity. The addition of hydrogen generally resulted in increased turbulent and laminar burning velocity and decreased Markstein number. Those flames that were less sensitive to stretch (lower Markstein number) burned faster under turbulent conditions, especially as the turbulence levels were increased, compared to stretch-sensitive (high Markstein number) flames. (author)

  8. CARBON DEFLAGRATION IN TYPE Ia SUPERNOVA. I. CENTRALLY IGNITED MODELS

    SciTech Connect (OSTI)

    Ma, H.; Woosley, S. E.; Malone, C. M. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Almgren, A.; Bell, J. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States)

    2013-07-01

    A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway close to its center and explodes. In a series of papers, we shall explore the consequences of ignition at several locations within such dwarfs. Here we assume central ignition, which has been explored before, but is worth revisiting, if only to validate those previous studies and to further elucidate the relevant physics for future work. A perturbed sphere of hot iron ash with a radius of {approx}100 km is initialized at the middle of the star. The subsequent explosion is followed in several simulations using a thickened flame model in which the flame speed is either fixed-within the range expected from turbulent combustion-or based on the local turbulent intensity. Global results, including the explosion energy and bulk nucleosynthesis (e.g., {sup 56}Ni of 0.48-0.56 M{sub Sun }) turn out to be insensitive to this speed. In all completed runs, the energy released by the nuclear burning is adequate to unbind the star, but not enough to give the energy and brightness of typical SNe Ia. As found previously, the chemical stratification observed in typical events is not reproduced. These models produce a large amount of unburned carbon and oxygen in central low velocity regions, which is inconsistent with spectroscopic observations, and the intermediate mass elements and iron group elements are strongly mixed during the explosion.

  9. Preparing for Ignition Experiments on the National Ignition Facility

    SciTech Connect (OSTI)

    Moses, E; Meier, W

    2007-08-28

    The National Ignition Facility (NIF) is a 192-beam Nd-glass laser facility presently under construction at Lawrence Livermore National Laboratory (LLNL) for performing ignition experiments for inertial confinement fusion (ICF) and experiments studying high energy density (HED) science. NIF will produce 1.8 MJ, 500 TW of ultraviolet light ({lambda} = 351 nm) making it the world's largest and most powerful laser system. NIF will be the world's preeminent facility for the study of matter at extreme temperatures and densities for producing and developing ICF. The ignition studies will be an essential step in developing inertial fusion energy (IFE). the NIF Project is over 93% complete and scheduled for completion in 2009. Experiments using one beam have demonstrated that NIF can meet all of its performance goals. A detailed plan called the National Ignition Campaign (NIC) has been developed to begin ignition experiments in 2010. The plan includes the target physics and the equipment such as diagnostics, cryogenic target manipulator and user optics required for the ignition experiment. Target designs have been developed that calculate to ignite at energy as low as 1 MJ. Plans are under way to make NIF a national user facility for experiments on HED physics and nuclear science, including experiments relevant to the development of IFE.

  10. Structure and Dynamics of Fuel Jets Injected into a High-Temperature Subsonic Crossflow: High-Data-Rate Laser Diagnostic Investigation under Steady and Oscillatory Conditions

    SciTech Connect (OSTI)

    Lucht, Robert; Anderson, William

    2015-01-23

    An investigation of subsonic transverse jet injection into a subsonic vitiated crossflow is discussed. The reacting jet in crossflow (RJIC) system investigated as a means of secondary injection of fuel in a staged combustion system. The measurements were performed in test rigs featuring (a) a steady, swirling crossflow and (b) a crossflow with low swirl but significant oscillation in the pressure field and in the axial velocity. The rigs are referred to as the steady state rig and the instability rig. Rapid mixing and chemical reaction in the near field of the jet injection is desirable in this application. Temporally resolved velocity measurements within the wake of the reactive jets using 2D-PIV and OH-PLIF at a repetition rate of 5 kHz were performed on the RJIC flow field in a steady state water-cooled test rig. The reactive jets were injected through an extended nozzle into the crossflow which is located in the downstream of a low swirl burner (LSB) that produced the swirled, vitiated crossflow. Both H2/N2 and natural gas (NG)/air jets were investigated. OH-PLIF measurements along the jet trajectory show that the auto-ignition starts on the leeward side within the wake region of the jet flame. The measurements show that jet flame is stabilized in the wake of the jet and wake vortices play a significant role in this process. PIV and OH–PLIF measurements were performed at five measurement planes along the cross- section of the jet. The time resolved measurements provided significant information on the evolution of complex flow structures and highly transient features like, local extinction, re-ignition, vortex-flame interaction prevalent in a turbulent reacting flow. Nanosecond-laser-based, single-laser-shot coherent anti-Stokes Raman scattering (CARS) measurements of temperature and H2 concentraiton were also performed. The structure and dynamics of a reacting transverse jet injected into a vitiated oscillatory crossflow presents a unique opportunity for applying advanced experimental diagnostic techniques with increasing fidelity for the purposes of computational validation and model development. Numerical simulation of the reacting jet in crossflow is challenging because of the complex vortical structures in the flowfield and compounded by an unsteady crossflow. The resulting benchmark quality data set will include comprehensive, accurate measurements of mean and fluctuating components of velocity, pressure, and flame front location at high pressure and with crossflow conditions more representative of modern gas turbine engines. A proven means for producing combustion dynamics is used for the performing combustion instability experimental study on a reacting jet in crossflow configuration. The method used to provide an unsteady flowfield into which the transverse jet is injected is a unique and novel approach that permits elevated temperature and pressure conditions. A model dump combustor is used to generate and sustain an acoustically oscillating vitiated flow that serves as the crossflow for transverse jet injection studies. A fully optically accessible combustor test section affords full access surrounding the point of jet injection. High speed 10 kHz planar measurements OH PLIF and high frequency 180 kHz wall pressure measurements are performed on the injected reacting transverse jet and surrounding flowfield, respectively, under simulated unstable conditions. The overlay of the jet velocity flowfield and the flame front will be investigated using simultaneous 10 kHz OH PLIF and PIV in experiments to be performed in the near future.

  11. Large Eddy Simulations of Jet Flow Interactions Within Rod Bundles 

    E-Print Network [OSTI]

    Salpeter, Nathaniel O.

    2010-07-14

    The present work investigates the turbulent jet flow mixing of downward impinging jets within a staggered rod bundle based on previous experimental work. The two inlet jets had Reynold's numbers of 11,160 and 6,250 and were chosen to coincide...

  12. The formation and evolution of synthetic jets Barton L. Smitha)

    E-Print Network [OSTI]

    Smith, Barton L.

    The formation and evolution of synthetic jets Barton L. Smitha) and Ari Glezer Woodruff School 1997; accepted 6 May 1998 A nominally plane turbulent jet is synthesized by the interactions of a train of a flexible diaphragm in a sealed cavity. Even though the jet is formed without net mass injection

  13. Axisymmetric Synthetic Jets: An Experimental and Theoretical Examination

    E-Print Network [OSTI]

    Mohseni, Kamran

    Axisymmetric Synthetic Jets: An Experimental and Theoretical Examination Gopi Krishnan and Kamran synthetic jet driven by a piezoelectric membrane issuing into a quiescent environment is studied in this paper. The self-similar behavior exhibited by both synthetic and continuous turbulent jets leads

  14. TOWARD A STANDARD IGNITION SOURCE

    E-Print Network [OSTI]

    Volkingburg, David R. Van

    2011-01-01

    and ignited with a small propane torch. The top center ofhead is supplied with propane. In these experiments allin the pre-mixed mode with propane alone to simulate trash

  15. The National Ignition Facility Project

    SciTech Connect (OSTI)

    Paisner, J.A.; Campbell, E.M.; Hogan, W.J.

    1994-06-16

    The mission of the National Ignition Facility is to achieve ignition and gain in ICF targets in the laboratory. The facility will be used for defense applications such as weapons physics and weapons effect testing, and for civilian applications such as fusion energy development and fundamental studies of matter at high temperatures and densities. This paper reviews the design, schedule and costs associated with the construction project.

  16. IGNITION AND FRONTIER SCIENCE ON THE NATIONAL IGNITION FACILITY

    SciTech Connect (OSTI)

    Moses, E

    2009-06-22

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and experiments studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF construction Project was certified by the Department of Energy as complete on March 30, 2009. NIF, a 192-beam Nd-glass laser facility, will produce 1.8 MJ, 500 TW of light at the third-harmonic, ultraviolet light of 351 nm. On March 10, 2009, a total 192-beam energy of 1.1 MJ was demonstrated; this is approximately 30 times more energy than ever produced in an ICF laser system. The principal goal of NIF is to achieve ignition of a deuterium-tritium (DT) fuel capsule and provide access to HED physics regimes needed for experiments related to national security, fusion energy and for broader frontier scientific exploration. NIF experiments in support of indirect drive ignition will begin in FY2009. These first experiments represent the next phase of the National Ignition Campaign (NIC). The NIC is a 1.7 billion dollar national effort to achieve fusion ignition and is coordinated through a detailed execution plan that includes the science, technology, and equipment. Equipment required for ignition experiments include diagnostics, cryogenic target manipulator, and user optics. Participants in this effort include LLNL, General Atomics (GA), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), and the University of Rochester Laboratory for Energetics (LLE). The primary goal for NIC is to have all of the equipment operational and integrated into the facility and be ready to begin a credible ignition campaign in 2010. With NIF now operational, the long-sought goal of achieving self-sustained nuclear fusion and energy gain in the laboratory is much closer to realization. Successful demonstration of ignition and net energy gain on NIF will be a major step towards demonstrating the feasibility of Inertial Fusion Energy (IFE) and will likely focus the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed and has high probability of success. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and Fast Ignition concepts. Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. The NIC will develop the full set of capabilities required to operate NIF as a major national and international user facility. A solicitation for NIF frontier science experiments to be conducted by the academic community is planned for summer 2009. This paper summarizes the design, performance, and status of NIF, experimental plans for NIC, and will present a brief discussion of the unparalleled opportunities to explore frontier basic science that will be available on the NIF.

  17. SCB thermite igniter studies

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.; Wackerbarth, D.E.; Mohler, J.H.

    1996-12-31

    The authors report on recent studies comparing the ignition threshold of temperature cycled, SCB thermite devices with units that were not submitted to temperature cycling. Aluminum/copper-oxide thermite was pressed into units at two densities, 45% of theoretical maximum density (TMD) or 47% of TMD. Half of each of the density sets underwent three thermal cycles; each cycle consisted of 2 hours at 74 C and 2 hours at {minus}54 C, with a 5 minute maximum transfer time between temperatures. The temperature cycled units were brought to ambient temperature before the threshold testing. Both the density and the thermal cycling affected the all-fire voltage. Using a 5.34 {micro}F CDU (capacitor discharge unit) firing set, the all-fire voltage for the units that were not temperature cycled increased with density from 32.99 V (45% TMD) to 39.32 V (47% TMD). The all-fire voltages for the thermally cycled units were 34.42 V (45% TMD) and 58.1 V (47% TMD). They also report on no-fire levels at ambient temperature for two component designs; the 5 minute no-fire levels were greater than 1.2 A. Units were also subjected to tests in which 1 W of RF power was injected into the bridges at 10 MHz for 5 minutes. The units survived and fired normally afterwards. Finally, units were subjected to pin-to-pin electrostatic discharge (ESD) tests. None of the units fired upon application of the ESD pulse, and all of the tested units fired normally afterwards.

  18. Enhanced Model for Fast Ignition

    SciTech Connect (OSTI)

    Dr. Rodney J. Mason

    2010-10-12

    Laser Fusion is a prime candidate for alternate energy production, capable of serving a major portion of the nationâ??s energy needs, once fusion fuel can be readily ignited. Fast Ignition may well speed achievement of this goal, by reducing net demands on laser pulse energy and timing precision. However, Fast Ignition has presented a major challenge to modeling. This project has enhanced the computer code ePLAS for the simulation of the many specialized phenomena, which arise with Fast Ignition. The improved code has helped researchers to understand better the consequences of laser absorption, energy transport, and laser target hydrodynamics. ePLAS uses efficient implicit methods to acquire solutions for the electromagnetic fields that govern the accelerations of electrons and ions in targets. In many cases, the code implements fluid modeling for these components. These combined features, â??implicitness and fluid modeling,â? can greatly facilitate calculations, permitting the rapid scoping and evaluation of experiments. ePLAS can be used on PCs, Macs and Linux machines, providing researchers and students with rapid results. This project has improved the treatment of electromagnetics, hydrodynamics, and atomic physics in the code. It has simplified output graphics, and provided new input that avoids the need for source code access by users. The improved code can now aid university, business and national laboratory users in pursuit of an early path to success with Fast Ignition.

  19. Thermonuclear Ignition of Dark Galaxies

    E-Print Network [OSTI]

    J. Marvin Herndon

    2006-04-13

    Dark matter is thought to be at least an order of magnitude more abundant than luminous matter in the Universe, but there has yet to be an unambiguous identification of a wholly dark, galactic-scale structure. There is, however, increasing evidence that VIRGOHI 21 may be a dark galaxy. If VIRGOHI 21 turns out to be composed of dark stars, having approximately the same mass of stars found in luminous galaxies, it will pose an enigma within the framework of current astrophysical models, but will provide strong support for my concept, published in 1994 in the Proceedings of the Royal Society of London, of the thermonuclear ignition of stars by nuclear fission, and the corollary, non-ignition of stars. The possibility of galactic thermonuclear ignition is discussed from that framework and leads to my suggestion that the distribution of luminous stars in a galaxy may simply be a reflection of the galactic distribution of the heavy elements.

  20. Laser ablation based fuel ignition

    DOE Patents [OSTI]

    Early, J.W.; Lester, C.S.

    1998-06-23

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.

  1. Laser ablation based fuel ignition

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    1998-01-01

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition.

  2. Integral low-energy thermite igniter

    DOE Patents [OSTI]

    Gibson, A.; Haws, L.D.; Mohler, J.H.

    1983-05-13

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  3. Integral low-energy thermite igniter

    DOE Patents [OSTI]

    Gibson, Albert (Dayton, OH); Haws, Lowell D. (Springboro, OH); Mohler, Jonathan H. (Spring Valley, OH)

    1984-08-14

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  4. Advanced ignition options for laser ICF

    E-Print Network [OSTI]

    University of Rochester and Princeton Plasma Physics Laboratory #12;FSC · With day-one hardware, the NIF can explore high-gain shock ignition - Polar Shock Ignition (uses half the NIF beams to drive the implosion: multi-FM or 2D-SSD (talk by J. Soures at this meeting) The NIF can explore advanced ignition options

  5. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, R.B.

    1994-08-16

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct. 11 figs.

  6. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, Robert B. (Wheatridge, CO)

    1994-01-01

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct.

  7. Simulation of turbulent flames relevant to spark-ignition engines

    E-Print Network [OSTI]

    Ahmed, Irufan

    2014-04-29

    in 2010 being based on fossil fuels and it is predicted to account for 83% share in 2035 (IEA, 2011). Most motor vehicles today use reciprocating internal combustion (IC) engines, which burn fossil fuels to convert chemical energy stored in the fuel... and oxidiser are transported sep- arately into the reaction zones by diffusion. Aero-engine gas turbines and diesel engines are typical examples of non-premixed combustion. It is often the case in practical systems that fuel and air is not completely mixed...

  8. Simultaneous dual mode combustion engine operating on spark ignition and homogenous charge compression ignition

    DOE Patents [OSTI]

    Fiveland, Scott B.; Wiggers, Timothy E.

    2004-06-22

    An engine particularly suited to single speed operation environments, such as stationary power generators. The engine includes a plurality of combustion cylinders operable under homogenous charge compression ignition, and at least one combustion cylinder operable on spark ignition concepts. The cylinder operable on spark ignition concepts can be convertible to operate under homogenous charge compression ignition. The engine is started using the cylinders operable under spark ignition concepts.

  9. Primary Atomization of a Liquid Jet in Crossflow

    E-Print Network [OSTI]

    Rana, Sandeep

    2010-01-01

    In this fluid dynamics video, we present a visualization of the primary atomization of a turbulent liquid jet injected into a turbulent gaseous crossflow. It is based on a detailed numerical simulation of the primary atomization region of the jet using a finite volume, balanced force, incompressible LES/DNS flow solver coupled to a Refined Level Set Grid (RLSG) solver to track the phase interface position. The visualization highlights the two distinct breakup modes of the jet: the column breakup mode of the main liquid column and the ligament breakup mode on the sides of the jet and highlights the complex evolution of the phase interface geometry.

  10. Fuzzy Jets

    E-Print Network [OSTI]

    Mackey, Lester; Schwartzman, Ariel; Stansbury, Conrad

    2015-01-01

    Collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets. To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets, are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet tagging variables. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.

  11. Fuzzy Jets

    E-Print Network [OSTI]

    Lester Mackey; Benjamin Nachman; Ariel Schwartzman; Conrad Stansbury

    2015-09-07

    Collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets. To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets, are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet tagging variables. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.

  12. 44th AIAA Aerospace Sciences Meeting and Exhibit, Jan 912, Reno, Nevada Passive scalar mixing in jets in crossflow

    E-Print Network [OSTI]

    Mahesh, Krishnan

    in jets in crossflow Suman Muppidi and Krishnan Mahesh University of Minnesota, Minneapolis, MN, 55455 turbulent jet in a laminar crossflow. The velocity ratio of the jet to that of the crossflow is 5.7, the Schmidt number of the scalar is 1.49, and the jet­exit Reynolds number is 5000. The scalar field is used

  13. Diagnostics for Fast Ignition Science

    SciTech Connect (OSTI)

    MacPhee, A; Akli, K; Beg, F; Chen, C; Chen, H; Clarke, R; Hey, D; Freeman, R; Kemp, A; Key, M; King, J; LePape, S; Link, A; Ma, T; Nakamura, N; Offermann, D; Ovchinnikov, V; Patel, P; Phillips, T; Stephens, R; Town, R; Wei, M; VanWoerkom, L; Mackinnon, A

    2008-05-06

    The concept for Electron Fast Ignition Inertial Confinement Fusion demands sufficient laser energy be transferred from the ignitor pulse to the assembled fuel core via {approx}MeV electrons. We have assembled a suite of diagnostics to characterize such transfer. Recent experiments have simultaneously fielded absolutely calibrated extreme ultraviolet multilayer imagers at 68 and 256eV; spherically bent crystal imagers at 4 and 8keV; multi-keV crystal spectrometers; MeV x-ray bremmstrahlung and electron and proton spectrometers (along the same line of sight); nuclear activation samples and a picosecond optical probe based interferometer. These diagnostics allow careful measurement of energy transport and deposition during and following laser-plasma interactions at extremely high intensities in both planar and conical targets. Augmented with accurate on-shot laser focal spot and pre-pulse characterization, these measurements are yielding new insight into energy coupling and are providing critical data for validating numerical PIC and hybrid PIC simulation codes in an area that is crucial for many applications, particularly fast ignition. Novel aspects of these diagnostics and how they are combined to extract quantitative data on ultra high intensity laser plasma interactions are discussed, together with implications for full-scale fast ignition experiments.

  14. Wave Packets and Turbulent Peter Jordan1

    E-Print Network [OSTI]

    Dabiri, John O.

    Wave Packets and Turbulent Jet Noise Peter Jordan1 and Tim Colonius2 1 D´epartement Fluides-control efforts is incomplete. Wave packets are intermittent, advecting disturbances that are correlated over review evidence of the existence, energetics, dynamics, and acous- tic efficiency of wave packets. We

  15. Jets in Soft-Collinear Effective Theory

    E-Print Network [OSTI]

    Hornig, Andrew

    2010-01-01

    Jet Functions . . . . . . . . . . . . . . . . . . . .Event Shapes . . . . . . . . . . . . . . . . . . . . . JetQuark Jet

  16. Investigation of ignition of thermoplastics through the Hot Wire Ignition Test 

    E-Print Network [OSTI]

    De Araujo, Luiz Claudio Bonilla

    1998-01-01

    in enclosures or insulation systems of electrical equipment. The main objective of this project was to identify the effect of specimen thickness on the ignition time. In addition, temperature changes at the surface of some materials during the ignition process...

  17. Fast ignition of inertial confinement fusion targets

    SciTech Connect (OSTI)

    Gus'kov, S. Yu., E-mail: guskov@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2013-01-15

    Results of studies on fast ignition of inertial confinement fusion (ICF) targets are reviewed. The aspects of the fast ignition concept, which consists in the separation of the processes of target ignition and compression due to the synchronized action of different energy drivers, are considered. Criteria for the compression ratio and heating rate of a fast ignition target, the energy balance, and the thermonuclear gain are discussed. The results of experimental and theoretical studies of the heating of a compressed target by various types of igniting drivers, namely, beams of fast electrons and light ions produced under the action of a petawatt laser pulse on the target, a heavy-ion beam generated in the accelerator, an X-ray pulse, and a hydrodynamic flow of laser-accelerated matter, are analyzed. Requirements to the igniting-driver parameters that depend on the fast ignition criteria under the conditions of specific target heating mechanisms, as well as possibilities of practical implementation of these requirements, are discussed. The experimental programs of various laboratories and the prospects of practical implementation of fast ignition of ICF targets are reviewed. To date, fast ignition is the most promising method for decreasing the ignition energy and increasing the thermonuclear gain of an ICF plasma. A large number of publications have been devoted to investigations of this method and adjacent problems of the physics of igniting drivers and their interaction with plasma. This review presents results of only some of these studies that, in the author's opinion, allow one to discuss in detail the main physical aspects of the fast ignition concept and understand the current state and prospects of studies in this direction.

  18. An experimental study of jet impingement on a circular cylinder 

    E-Print Network [OSTI]

    Potts, Dennis Wayne

    1984-01-01

    profile for U = 550 ft/s, x/d = 30 (radial 2) 1 30 85 Wall jet turbulence profile for U = 550 ft/s, x/d = 30 ( radial 4) 131 86 Wall jet turbulence profile for Uo5 50 f t/ s, x/ d= 30(ax i al rad i al ) 132 Spread r ate of the wall jet along the axis... of the cylinder a compar ed to a flat plate . . . . 140 95 Velocity scale of the wall jet for U = 400 ft/s, x/d = 7 141 96 Velocity scale of the wall jet for U = 400 ft/s, x/d = 15 142 97 Velocity scale of tne wall jet for Uo 4 0 0 f t / s x / d 3 0 143 9S...

  19. Sandia Energy - Particle Ignition and Char Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of CO2 and H2O (from flue gas recirculation) create very different physical and chemical properties of the combustion medium, influencing coal ignition and combustion rates....

  20. High Efficiency Fuel Reactivity Controlled Compression Ignition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    High Efficiency Fuel Reactivity Controlled Compression Ignition Combustion An optimized dual-fuel PCCI concept, RCCI, is proposed. deer10reitz.pdf More Documents & Publications...

  1. Progress towards ignition on the National Ignition Facility

    SciTech Connect (OSTI)

    Edwards, M. J.; Patel, P. K.; Lindl, J. D.; Atherton, L. J.; Glenzer, S. H.; Haan, S. W.; Landen, O. L.; Moses, E. I.; Springer, P. T.; Benedetti, R.; Bernstein, L.; Bleuel, D. L.; Bradley, D. K.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C. J.; Clark, D. S.; Collins, G. W.; Dewald, E. L. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); and others

    2013-07-15

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory includes a precision laser system now capable of delivering 1.8 MJ at 500 TW of 0.35-?m light to a target. NIF has been operational since March 2009. A variety of experiments have been completed in support of NIF's mission areas: national security, fundamental science, and inertial fusion energy. NIF capabilities and infrastructure are in place to support its missions with nearly 60 X-ray, optical, and nuclear diagnostic systems. A primary goal of the National Ignition Campaign (NIC) on the NIF was to implode a low-Z capsule filled with ?0.2 mg of deuterium-tritium (DT) fuel via laser indirect-drive inertial confinement fusion and demonstrate fusion ignition and propagating thermonuclear burn with a net energy gain of ?5–10 (fusion yield/input laser energy). This requires assembling the DT fuel into a dense shell of ?1000 g/cm{sup 3} with an areal density (?R) of ?1.5 g/cm{sup 2}, surrounding a lower density hot spot with a temperature of ?10 keV and a ?R ?0.3 g/cm{sup 2}, or approximately an ?-particle range. Achieving these conditions demand precise control of laser and target parameters to allow a low adiabat, high convergence implosion with low ablator fuel mix. We have demonstrated implosion and compressed fuel conditions at ?80–90% for most point design values independently, but not at the same time. The nuclear yield is a factor of ?3–10× below the simulated values and a similar factor below the alpha dominated regime. This paper will discuss the experimental trends, the possible causes of the degraded performance (the off-set from the simulations), and the plan to understand and resolve the underlying physics issues.

  2. Combustion characteristics of indolene-methanol blends in a CFR spark ignition engine

    SciTech Connect (OSTI)

    Patel, K.S.

    1984-01-01

    A study of the combustion characteristics of indolene, methanol and indolene-methanol blends has been completed. The investigation included theoretical and experimental parts. In the theoretical part, turbulent burning velocity, laminar burning velocity, and mass burning velocity are computed. The experimental part was completed on a CFR spark ignition engine using indolene, methanol, and indolene-methanol blends. Methanol concentration was varied from 0 to 100 vol.%. For each blend, compression ratio was varied from 5.0 to KLCR (Knock Limited Compression Ratio). The results of theoretical analysis showed that the laminar burning velocity increased as the vol.% of methanol increased. The experimental results indicated that adding methanol to indolene, MBT (Minimum advanced for Best Torque) spark advance, volumetric efficiency, brake mean effective pressure are decreased while break specific fuel consumption, brake thermal efficiency an KLCR are increased. The theoretical and experimental results showed that adding methanol to indolene, apparent flame speed, turbulent burning velocity and the ratio of turbulent to laminar burning velocity increased. Pure methanol produced the highest turbulent burning velocity. It is concluded that methanol has considerable effect on the combustion characteristics of spark ignition engine.

  3. SMALL-APERTURE PHASED ARRAY STUDY OF NOISE FROM COAXIAL JETS

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    SMALL-APERTURE PHASED ARRAY STUDY OF NOISE FROM COAXIAL JETS Dimitri Papamoschou University of California, Irvine, California 92697-3975 The noise source distribution of coaxial jets at variable velocity by fine- scale turbulence (broadside direction). For zero velocity ratio (single-stream jet), the near

  4. Stellar jets

    E-Print Network [OSTI]

    Thomas J. Maccarone

    2008-05-23

    With a goal of understanding the conditions under which jets might be produced in novae and related objects, I consider the conditions under which jets are produced from other classes of accreting compact objects. I give an overview of accretion disk spectral states, including a discussion of in which states these jets are seen. I highlight the differences between neutron stars and black holes, which may help give us insights about when and how the presence of a solid surface may help or inhibit jet production.

  5. Gravitomagnetic Jets

    E-Print Network [OSTI]

    C. Chicone; B. Mashhoon

    2011-03-12

    We present a family of dynamic rotating cylindrically symmetric Ricci-flat gravitational fields whose geodesic motions have the structure of gravitomagnetic jets. These correspond to helical motions of free test particles up and down parallel to the axis of cylindrical symmetry and are reminiscent of the motion of test charges in a magnetic field. The speed of a test particle in a gravitomagnetic jet asymptotically approaches the speed of light. Moreover, numerical evidence suggests that jets are attractors. The possible implications of our results for the role of gravitomagnetism in the formation of astrophysical jets are briefly discussed.

  6. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect (OSTI)

    Im, Hong G [University of Michigan] [University of Michigan; Trouve, Arnaud [University of Maryland] [University of Maryland; Rutland, Christopher J [University of Wisconsin] [University of Wisconsin; Chen, Jacqueline H [Sandia National Laboratories] [Sandia National Laboratories

    2012-08-13

    The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. The code named S3D, developed and shared with Chen and coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for spray dynamics, combustion, and pollutant formation processes in turbulent combustion. Major accomplishments include improved characteristic boundary conditions, fundamental studies of auto-ignition in turbulent stratified reactant mixtures, flame-wall interaction, and turbulent flame extinction by water spray. The overarching scientific issue in our recent investigations is to characterize criticality phenomena (ignition/extinction) in turbulent combustion, thereby developing unified criteria to identify ignition and extinction conditions. The computational development under TSTC has enabled the recent large-scale 3D turbulent combustion simulations conducted at Sandia National Laboratories.

  7. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect (OSTI)

    Hong G. Im; Arnaud Trouve; Christopher J. Rutland; Jacqueline H. Chen

    2009-02-02

    The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. The code named S3D, developed and shared with Chen and coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for spray dynamics, combustion, and pollutant formation processes in turbulent combustion. Major accomplishments include improved characteristic boundary conditions, fundamental studies of auto-ignition in turbulent stratified reactant mixtures, flame-wall interaction, and turbulent flame extinction by water spray. The overarching scientific issue in our recent investigations is to characterize criticality phenomena (ignition/extinction) in turbulent combustion, thereby developing unified criteria to identify ignition and extinction conditions. The computational development under TSTC has enabled the recent large-scale 3D turbulent combustion simulations conducted at Sandia National Laboratories.

  8. High Fidelity Modeling of Premixed Charge Compression Ignition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Fidelity Modeling of Premixed Charge Compression Ignition Engines High Fidelity Modeling of Premixed Charge Compression Ignition Engines Most accurate and detailed chemical kinetic...

  9. Modeling the Number of Ignitions Following an Earthquake: Developing...

    Office of Environmental Management (EM)

    Modeling the Number of Ignitions Following an Earthquake: Developing Prediction Limits for Overdispersed Count Data Modeling the Number of Ignitions Following an Earthquake:...

  10. Effects of Ignition Quality and Fuel Composition on Critical...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Ignition Quality and Fuel Composition on Critical Equivalence Ratio Effects of Ignition Quality and Fuel Composition on Critical Equivalence Ratio Our research shows that fuel can...

  11. Light-Duty Reactivity Controlled Compression Ignition Drive Cycle...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Light-Duty Reactivity Controlled Compression Ignition Drive Cycle Fuel Economy and Emissions Estimates Light-Duty Reactivity Controlled Compression Ignition Drive Cycle Fuel...

  12. Effect of Premixed Charge Compression Ignition on Vehicle Fuel...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Premixed Charge Compression Ignition on Vehicle Fuel Economy and Emissions Reduction over Transient Driving Cycles Effect of Premixed Charge Compression Ignition on Vehicle Fuel...

  13. Pyrotechnic ignition studies using a gun tunnel

    SciTech Connect (OSTI)

    Evans, N.A.

    1989-01-01

    A gun tunnel is being used to investigate the ignition characteristics of center-hole iron/potassium perchlorate thermal battery discs. Details are given of the construction, operation, and data reduction method for the gun tunnel. To simulate an igniter, this system can readily produce a pulse of hot argon at maximum pressures and temperatures up to P/sub max/ = 8 MPa and T/sub max/ = 4000K, respectively, with flow times of the order of 3 msec. For a single battery disc, a segment of the ignition boundary was found to lie in the region of T/sub max/ = 1200 to 1300K and 0.7 MPa < P/sub max/ < 2.0 MPa. The results also showed two types of ignition: prompt ignition, requiring an average delivered enthalpy /ovr /Delta/H//sub ig/ = 6 cal during an average flow time /ovr /Delta/t//sub ig/ = 0.7 msec, and delayed ignition, with /ovr /Delta/H//sub ig/ = 16 cal and /ovr /Delta/t//sub ig/ = 2.4 msec. In addition, near an ignition boundary, high speed motion photography showed the ignition delay increased to 6 msec with significant spatial non-uniformity. 1 ref., 6 figs.

  14. The National Ignition Campaign Presentation to

    E-Print Network [OSTI]

    of the diagnostics and infrastructure needed for optimizing ignition implosions are essentially independent to identify the optimal tradeoff between Laser Plasma Interaction effects, hydrodynamic instability and laser Hydro Risk 5 End of 2010 #12;Projected ignition scale hohlraum temperature from initial hohlraum

  15. UCRL-PRES-225531 National ignition facility

    E-Print Network [OSTI]

    shock Point Design pulse Outer cone Time (ns) This level of capability is unique to NIF NIC ignition ignition Campaign 2006 #12;Major elements of the NIC #12;31 NIF Indirect Drive target point design #12;MOVIE: Fill tube #12;Low-Yield diagnostics #12;NIC High yield diagnostics #12;35 NIF/NIC Integration

  16. Managing transient behaviors of a dual mode spark ignition-- controlled auto ignition engine with a variable valve timing system

    E-Print Network [OSTI]

    Santoso, Halim G. (Halim Gustiono), 1975-

    2005-01-01

    Gasoline Homogeneous Charge Compression Ignition (HCCI) engine has the potential of providing better fuel economy and emissions characteristics than current spark ignition engines. One implementation of this technology ...

  17. Turbulence-chemistry interactions in reacting flows

    SciTech Connect (OSTI)

    Barlow, R.S.; Carter, C.D. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    Interactions between turbulence and chemistry in nonpremixed flames are investigated through multiscalar measurements. Simultaneous point measurements of major species, NO, OH, temperature, and mixture fraction are obtained by combining spontaneous Raman scattering, Rayleigh scattering, and laser-induced fluorescence (LIF). NO and OH fluorescence signals are converted to quantitative concentrations by applying shot-to-shot corrections for local variations of the Boltzmann fraction and collisional quenching rate. These measurements of instantaneous thermochemical states in turbulent flames provide insights into the fundamental nature of turbulence-chemistry interactions. The measurements also constitute a unique data base for evaluation and refinement of turbulent combustion models. Experimental work during the past year has focused on three areas: (1) investigation of the effects of differential molecular diffusion in turbulent combustion: (2) experiments on the effects of Halon CF{sub 3}Br, a fire retardant, on the structure of turbulent flames of CH{sub 4} and CO/H{sub 2}/N{sub 2}; and (3) experiments on NO formation in turbulent hydrogen jet flames.

  18. Cosmic Jets

    E-Print Network [OSTI]

    C. Chicone; B. Mashhoon; K. Rosquist

    2011-02-17

    We discuss time-dependent gravitational fields that "accelerate" free test particles to the speed of light resulting in cosmic double-jet configurations. It turns out that complete gravitational collapse along a spatial axis together with corresponding expansion along the other two axes leads to the accelerated motion of free test particles up and down parallel to the collapse axis such that a double-jet pattern is asymptotically formed with respect to the collapsed configuration.

  19. Emerging Jets

    E-Print Network [OSTI]

    Pedro Schwaller; Daniel Stolarski; Andreas Weiler

    2015-05-11

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilities for discovery at LHCb are also discussed.

  20. Thermonuclear ignition in inertial confinement fusion and comparison with magnetic confinement

    SciTech Connect (OSTI)

    Betti, R.; Chang, P. Y.; Anderson, K. S.; Nora, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Fusion Science Center for Extreme States of Matter, University of Rochester, Rochester, New York 14623 (United States); Spears, B. K.; Edwards, J.; Lindl, J. D. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Fatenejad, M. [Department of Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); McCrory, R. L. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Shvarts, D. [NRCN, Negev and Ben Gurion University of the Negev, Beer-Sheva 84015 (Israel)

    2010-05-15

    The physics of thermonuclear ignition in inertial confinement fusion (ICF) is presented in the familiar frame of a Lawson-type criterion. The product of the plasma pressure and confinement time Ptau for ICF is cast in terms of measurable parameters and its value is estimated for cryogenic implosions. An overall ignition parameter chi including pressure, confinement time, and temperature is derived to complement the product Ptau. A metric for performance assessment should include both chi and Ptau. The ignition parameter and the product Ptau are compared between inertial and magnetic-confinement fusion. It is found that cryogenic implosions on OMEGA[T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have achieved Ptauapprox1.5 atm s comparable to large tokamaks such as the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] where Ptauapprox1 atm s. Since OMEGA implosions are relatively cold (Tapprox2 keV), their overall ignition parameter chiapprox0.02-0.03 is approx5x lower than in JET (chiapprox0.13), where the average temperature is about 10 keV.

  1. Jet observables without jet algorithms

    E-Print Network [OSTI]

    Bertolini, Daniele

    We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but ...

  2. Sandia Energy - Turbulent Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Combustion Home Transportation Energy Predictive Simulation of Engines Reacting Flow Experiments Turbulent Combustion Turbulent CombustionAshley Otero2015-10-30T01:39:47+00...

  3. Igniting Engaged Scholars: The Graduate Certification in

    E-Print Network [OSTI]

    Communication and Information Technology E-mail: bargerst@msu.edu Igniting Innovation: MSUglobal 10-year models) ­ Evaluating engaged partnerships ­ The ethics of engaged scholarship Offered face-to-face over

  4. Ignition methods and apparatus using microwave energy

    DOE Patents [OSTI]

    DeFreitas, Dennis Michael (Oxford, NY); Migliori, Albert (Santa Fe, NM)

    1997-01-01

    An ignition apparatus for a combustor includes a microwave energy source that emits microwave energy into the combustor at a frequency within a resonant response of the combustor, the combustor functioning as a resonant cavity for the microwave energy so that a plasma is produced that ignites a combustible mixture therein. The plasma preferably is a non-contact plasma produced in free space within the resonant cavity spaced away from with the cavity wall structure and spaced from the microwave emitter.

  5. Infrared Thermographic Study of Laser Ignition

    SciTech Connect (OSTI)

    Mohler, Jonathan H.; Chow, Charles T. S.

    1986-07-01

    Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet. The experimental apparatus used to make these observations is described. The temperature distributions recorded are shown to be in good agreement with those predicted by heat transfer theory. Heat content values calculated from the observed temperature distributions are used to calculate thermal and kinetic parameters for several samples. These values are found to be in reasonable agreement with theory.

  6. Infrared thermographic study of laser ignition

    SciTech Connect (OSTI)

    Mohler, J.H.; Chow, C.T.S.

    1986-07-21

    Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet.

  7. Transonic Combustion ?- Injection Strategy Development for Supercritical Gasoline Injection-Ignition in a Light Duty Engine

    Broader source: Energy.gov [DOE]

    Novel fuel injection equipment enables knock-free ignition with low noise and smoke in compression-ignition engines and low-particulates in spark-ignition engines.

  8. Dispersion in two-dimensional turbulent buoyant plumes

    E-Print Network [OSTI]

    Rocco, Stefano; Woods, Andrew W.

    2015-06-02

    terrestrial explosive volcanism. Journal of Geophysical Research 113 (B9), B09201. Chen, By Daoyi & Jirka, Gerhard H 1999 LIF study of plane jet bounded in shallow water layer. Journal of Hydraulic Engineering 125 (August), 817–826. Danckwerts, P. V. 1953... Continuous Flow Systems, Distribution of Residence Times. Chemical Engineering Science 2 (1). Daoyi, Chen & Jirka, Gerhard H. 1998 Linear stability analysis of turbulent mixing layers and jets in shallow water layers. Journal of Hydraulic Research 36 (5), 815...

  9. New perspectives on superparameterization for geophysical turbulence

    SciTech Connect (OSTI)

    Majda, Andrew J.; Grooms, Ian

    2014-08-15

    This is a research expository paper regarding superparameterization, a class of multi-scale numerical methods designed to cope with the intermittent multi-scale effects of inhomogeneous geophysical turbulence where energy often inverse-cascades from the unresolved scales to the large scales through the effects of waves, jets, vortices, and latent heat release from moist processes. Original as well as sparse space–time superparameterization algorithms are discussed for the important case of moist atmospheric convection including the role of multi-scale asymptotic methods in providing self-consistent constraints on superparameterization algorithms and related deterministic and stochastic multi-cloud parameterizations. Test models for the statistical numerical analysis of superparameterization algorithms are discussed both to elucidate the performance of the basic algorithms and to test their potential role in efficient multi-scale data assimilation. The very recent development of grid-free seamless stochastic superparameterization methods for geophysical turbulence appropriate for “eddy-permitting” mesoscale ocean turbulence is presented here including a general formulation and illustrative applications to two-layer quasigeostrophic turbulence, and another difficult test case involving one-dimensional models of dispersive wave turbulence. This last test case has randomly generated solitons as coherent structures which collapse and radiate wave energy back to the larger scales, resulting in strong direct and inverse turbulent energy cascades.

  10. Jet Quenching via Jet Collimation

    E-Print Network [OSTI]

    Jorge Casalderrey-Solana; Jose Guilherme Milhano; Urs Achim Wiedemann

    2010-12-03

    The ATLAS Collaboration recently reported strong modifications of dijet properties in heavy ion collisions. In this work, we discuss to what extent these first data constrain already the microscopic mechanism underlying jet quenching. Simple kinematic arguments lead us to identify a frequency collimation mechanism via which the medium efficiently trims away the soft components of the jet parton shower. Through this mechanism, the observed dijet asymmetry can be accomodated with values of $\\hat{q}\\, L$ that lie in the expected order of magnitude.

  11. Direct numerical simulation of turbulent reacting flows

    SciTech Connect (OSTI)

    Chen, J.H. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The development of turbulent combustion models that reflect some of the most important characteristics of turbulent reacting flows requires knowledge about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between the turbulence and the chemistry is so strong in certain regimes that is is very difficult to isolate the role played by one individual phenomenon. Direct numerical simulation (DNS) is an extremely useful tool to study in detail the turbulence-chemistry interactions in certain well defined regimes. Globally, non-premixed flames are controlled by two limiting cases: the fast chemistry limit, where the turbulent fluctuations. In between these two limits, finite-rate chemical effects are important and the turbulence interacts strongly with the chemical processes. This regime is important because industrial burners operate in regimes in which, locally the flame undergoes extinction, or is at least in some nonequilibrium condition. Furthermore, these nonequilibrium conditions strongly influence the production of pollutants. To quantify the finite-rate chemistry effect, direct numerical simulations are performed to study the interaction between an initially laminar non-premixed flame and a three-dimensional field of homogeneous isotropic decaying turbulence. Emphasis is placed on the dynamics of extinction and on transient effects on the fine scale mixing process. Differential molecular diffusion among species is also examined with this approach, both for nonreacting and reacting situations. To address the problem of large-scale mixing and to examine the effects of mean shear, efforts are underway to perform large eddy simulations of round three-dimensional jets.

  12. Haar LBP Gabor Jet boosting Gabor Jet

    E-Print Network [OSTI]

    Ai, Haizhou

    Boosting 1 boosting Haar LBP Gabor Jet boosting LBP Haar Gabor Jet boosting TP391. Further more, three kinds of local feature, Haar like feature, LBP histogram and Gabor jet are extracted, Haar like feature is more efficient for discriminating young and middle aged people, and Gabor Jet fits

  13. Thermonuclear supernova simulations with stochastic ignition

    E-Print Network [OSTI]

    W. Schmidt; J. C. Niemeyer

    2005-10-14

    We apply an ad hoc model for dynamical ignition in three-dimensional numerical simulations of thermonuclear supernovae assuming pure deflagrations. The model makes use of the statistical description of temperature fluctuations in the pre-supernova core proposed by Wunsch & Woosley (2004). Randomness in time is implemented by means of a Poisson process. We are able to vary the explosion energy and nucleosynthesis depending on the free parameter of the model which controls the rapidity of the ignition process. However, beyond a certain threshold, the strength of the explosion saturates and the outcome appears to be robust with respect to number of ignitions. In the most energetic explosions, we find about 0.75 solar masses of iron group elements. Other than in simulations with simultaneous multi-spot ignition, the amount of unburned carbon and oxygen at radial velocities of a few 1000 km/s tends to be reduced for an ever increasing number of ignition events and, accordingly, more pronounced layering results.

  14. Analytical model for fast-shock ignition

    SciTech Connect (OSTI)

    Ghasemi, S. A. Farahbod, A. H.; Sobhanian, S.

    2014-07-15

    A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI). The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ?4.5 MeV, the electrons effectively reach the central part of the fuel. To evaluate more realistically the performance of FSI approach, we have used a quasi-two temperature electron energy distribution function of Strozzi (2012) and fast ignitor energy formula of Bellei (2013) that are consistent with 3D PIC simulations for different values of fast ignitor laser wavelength and coupling efficiency. The general advantages of fast-shock ignition in comparison with the shock ignition can be estimated to be better than 1.3 and it is seen that the best results can be obtained for the fuel mass around 1.5 mg, fast ignitor laser wavelength ?0.3??micron and the shock ignitor energy weight factor about 0.25.

  15. CFD optimization study of high-efficiency jet ejectors 

    E-Print Network [OSTI]

    Watanawanavet, Somsak

    2009-05-15

    , separation, and energy consumption in the suction of the propelled stream. To maximize jet ejector performance, enhancing turbulent mixing should be a major consideration. The literatures indicate that the nozzle geometry should be well-designed to boost... design on jet ejector performance. In their experiment, two conically diverging nozzles were tested, but differing in the divergence angle. The exit and throat diameters of the nozzle were fixed in both cases. The experimental results show...

  16. Turbulent Flow Analysis and Coherent Structure Identification in Experimental Models with Complex Geometries 

    E-Print Network [OSTI]

    Amini, Noushin

    2012-02-14

    applying two different experimental methods. The first study involves the investigation of turbulent impinging jets through a staggered array of rods with or without crossflow. Such flows are crucial in various engineering disciplines. This experiment... ................................................................................................... 47 II.3.1. Time-Averaged Velocity Fields ................................................ 48 II.3.1.1. Single Impinging Jet in the Corner of Mid-Plane ...... 48 II.3.1.2. Single Impinging Jet in the Middle of the Measurement Plane...

  17. Pulsed jet combustion generator for premixed charge engines

    DOE Patents [OSTI]

    Oppenheim, A. K. (Berkeley, CA); Stewart, H. E. (Alameda, CA); Hom, K. (Hercules, CA)

    1990-01-01

    A method and device for generating pulsed jets which will form plumes comprising eddie structures, which will entrain a fuel/air mixture from the head space of an internal combustion engine, and mixing this fuel/air mixture with a pre-ignited fuel/air mixture of the plumes thereby causing combustion of the reactants to occur within the interior of the eddie structures.

  18. Ignition of THKP and TKP pyrotechnic powders :

    SciTech Connect (OSTI)

    Maharrey, Sean P.; Erikson, William W; Highley, Aaron M.; Wiese-Smith, Deneille; Kay, Jeffrey J

    2014-03-01

    We have conducted Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS) experiments on igniter/actuator pyrotechnic powders to characterize the reactive processes controlling the ignition and combustion behavior of these materials. The experiments showed a complex, interactive reaction manifold involving over ten reaction pathways. A reduced dimensionality reaction manifold was developed from the detailed 10-step manifold and is being incorporated into existing predictive modeling codes to simulate the performance of pyrotechnic powders for NW component development. The results from development of the detailed reaction manifold and reduced manifold are presented. The reduced reaction manifold has been successfully used by SNL/NM modelers to predict thermal ignition events in small-scale testing, validating our approach and improving the capability of predictive models.

  19. Ignition threshold for non-Maxwellian plasmas

    E-Print Network [OSTI]

    Hay, Michael J

    2015-01-01

    An optically thin $p$-$^{11}$B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. The minimum Lawson criterion for thermal $p$-$^{11}$B plasmas and the minimum $\\rho R$ required for ICF volume ignition are calculated. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for this utility, we consider a monoenergetic beam with particle energy selected to maximize the beam- thermal reactivity. Channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and $\\rho R$, improves reactivity at constant pressure, and could be used to remove helium ash. The gains realized with a beam thus establish an upper bound for the reductions in igniti...

  20. Low current extended duration spark ignition system

    DOE Patents [OSTI]

    Waters, Stephen Howard; Chan, Anthony Kok-Fai

    2005-08-30

    A system for firing a spark plug is disclosed. The system includes a timing controller configured to send a first timing signal and a second timing signal. The system also includes an ignition transformer having a primary winding and a secondary winding and a spark-plug that is operably associated with the secondary winding. A first switching element is disposed between the timing controller and the primary winding of the ignition transformer. The first switching element controls a supply of power to the primary winding based on the first timing signal. Also, a second switching element is disposed between the timing controller and the primary winding of the ignition transformer. The second switching element controls the supply of power to the primary winding based on the second timing signal. A method for firing a spark plug is also disclosed.

  1. Ignition of deuterium-tritium fuel targets

    DOE Patents [OSTI]

    Musinski, D.L.; Mruzek, M.T.

    1991-08-27

    Disclosed is a method of igniting a deuterium-tritium ICF fuel target to obtain fuel burn in which the fuel target initially includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell. The target is permitted to free-fall through a target chamber having walls heated by successive target ignitions, so that the target is uniformly heated during free-fall to at least partially melt the frozen fuel layer and form a liquid single-phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior shell surface. The falling target is then illuminated from exteriorly of the chamber while the fuel layer is at substantially uniformly single or bi-phase so as to ignite the fuel layer and release energy therefrom. 5 figures.

  2. APPLICATION OF FAULT TREE ANALYSIS TO IGNITION OF FIRE

    E-Print Network [OSTI]

    Teresa Ling, W.C.

    2011-01-01

    fuel is present in the vicinity of the potential ignition energy.energy property of the target fuel are usually constant. from the potential ignition source to the target fuel

  3. Precision Shock Tuning on the National Ignition Facility

    E-Print Network [OSTI]

    Frenje, Johan A.

    Ignition implosions on the National Ignition Facility [ J.?D. Lindl et al. Phys. Plasmas 11 339 (2004)] are underway with the goal of compressing deuterium-tritium fuel to a sufficiently high areal density (?R) to sustain ...

  4. Fuel effects in homogeneous charge compression ignition (HCCI) engines

    E-Print Network [OSTI]

    Angelos, John P. (John Phillip)

    2009-01-01

    Homogenous-charge, compression-ignition (HCCI) combustion is a new method of burning fuel in internal combustion (IC) engines. In an HCCI engine, the fuel and air are premixed prior to combustion, like in a spark-ignition ...

  5. Center for Turbulence Research Annual Research Briefs 2008

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    breakup of turbulent liquid jets in crossflow By M. G. Pai, O. Desjardins AND H. Pitsch 1. Motivation and objectives The problem of breakup of a liquid fuel in a crossflow finds relevance in applications in a crossflow is a result of a complex process that includes development of instabilities along the liquid

  6. DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

    SciTech Connect (OSTI)

    Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.; Falconer, David A.

    2010-09-01

    By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

  7. Chaotic Combustion in Spark Ignition Engines

    E-Print Network [OSTI]

    M. Wendeker; J. Czarnigowski; G. Litak; K. Szabelski

    2002-12-27

    We analyse the combustion process in a spark ignition engine using the experimental data of an internal pressure during the combustion process and show that the system can be driven to chaotic behaviour. Our conclusion is based on the observation of unperiodicity in the time series, suitable stroboscopic maps and a complex structure of a reconstructed strange attractor. This analysis can explain that in some circumstances the level of noise in spark ignition engines increases considerably due to nonlinear dynamics of a combustion process.

  8. Semiconductor bridge, SCB, ignition of energetic materials

    SciTech Connect (OSTI)

    Bickes, R.W.; Grubelich, M.D.; Harris, S.M.; Merson, J.A.; Tarbell, W.W.

    1997-04-01

    Sandia National Laboratories` semiconductor bridge, SCB, is now being used for the ignition or initiation of a wide variety of exeoergic materials. Applications of this new technology arose because of a need at the system level to provide light weight, small volume and low energy explosive assemblies. Conventional bridgewire devices could not meet the stringent size, weight and energy requirements of our customers. We present an overview of SCB technology and the ignition characteristics for a number of energetic materials including primary and secondary explosives, pyrotechnics, thermites and intermetallics. We provide examples of systems designed to meet the modern requirements that sophisticated systems must satisfy in today`s market environments.

  9. Plans for Ignition Experiments on NIF

    SciTech Connect (OSTI)

    Moses, E

    2007-07-27

    The National Ignition Facility (NIF) is a 192-beam Nd-glass laser facility presently under construction at Lawrence Livermore National Laboratory (LLNL) in support of inertial confinement fusion (ICF) and high-energy-density (HED) science. NIF will produce 1.8 MJ, 500 TW of ultraviolet light, making it the world's largest and most powerful laser system. NIF will be the world's preeminent facility for the study of matter at extreme temperatures and densities and for producing and developing ICF. The ignition studies will be the next important step in developing inertial fusion energy.

  10. ENHANCED IGNITION FOR I.C. ENGINES WITH PREMIXED CHARGE

    E-Print Network [OSTI]

    Dale, J.D.

    2013-01-01

    N, A. Features of Carburetor Engines With Torch Ignition,"D. A. "Carburetor Type Internal Combustion Engine With

  11. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect (OSTI)

    Schefer, R.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  12. Thermite powder ignition by localized microwaves Yehuda Meir, Eli Jerby

    E-Print Network [OSTI]

    Jerby, Eli

    Thermite powder ignition by localized microwaves Yehuda Meir, Eli Jerby Faculty of Engineering Keywords: Thermite Microwave heating Hotspots Thermal runaway Ignition a b s t r a c t This paper presents a new method to ignite pure thermite powder by low-power microwaves ($100 W). In this method

  13. Experimental study of gas turbine blade film cooling and internal turbulated heat transfer at large Reynolds numbers 

    E-Print Network [OSTI]

    Mhetras, Shantanu

    2009-06-02

    superposition of effectiveness data from individual rows are comparable with that from full coverage film cooling. Internal heat transfer measurements are also performed in a high aspect ratio channel and from jet array impingement on a turbulated target wall...

  14. Turbulent Nonpremixed Flames (TNF): Experimental Data Archives and Computational Submodels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    In the 1990s an international collaboration formed around a series of workshops that became known collectively as the International Workshop on Measurement and Computation of Turbulent Non-Premixed Flames (TNF). An online library, hosted by Sandia National Laboratory (California) was established that provides data sets and submodels or "mechanisms" for the study of turbulence-chemistry interactions in turbulent nonpremixed and partially premixed combustion. Data are organized by flame types: simple jet flames, piloted jet flames, bluff body flames, and swirl flames. These data sets provide a means for collaborative comparisons of both measured and simulated/modeled research results and also assist scientists in determining priorities for further research. More than 20 data sets or databases are available from this website, along with various downloadable files of chemical mechanisms. The website also provides an extensive bibliography and the proceedings of the workshops themselves from 1996 through 2012. Information continues to be added to this collection.

  15. PLIF measurement of fuel concentration distribution in transient hydrogen jet flame

    SciTech Connect (OSTI)

    Tomita, Eiji; Hamamoto, Yoshisuke; Yoshiyama, Sadami; Toda, Hitoshi

    1999-07-01

    To know the concentration field of fuel spray or jet is very important because the following combustion process strongly depends on it. Recently, planar laser induced fluorescence (PLIF) measurement is often used to clarify two-dimensional concentration field of fuel and other species. In this study, PLIF measurement was applied to investigate the concentration distribution of a transient hydrogen jet with combustion. The jet penetrates with entraining ambient air and hydrogen is mixed with the air. Each experimental run of the jet shows different configuration and concentration distribution although averaged jet shows axisymmetric ones. Normalized concentration in radial direction presents Gaussian distribution and normalized concentration in axial direction is expressed by the relation inverse to the axial direction. The mixture was ignited near the nozzle exit after some delay time (t = 3.6ms) during injection ({approximately}11ms). For example, the fuel concentration in the transient jet at t = 1.0 and 1.4ms after the spark ignition (t = 4.6 and 5.0 ms respectively) was obtained as shown in a figure. The behavior of the flame development was measured in the transient flame jet by analyzing these images. The velocities of the jet and flame tips were also determined.

  16. Investigation of spark discharge processes and ignition systems for spark-ignited internal combustion engines 

    E-Print Network [OSTI]

    Khare, Yogesh Jayant

    2000-01-01

    Spark ignition of the air-fuel mixture at the appropriate time is important for successful flame initiation and complete combustion thereafter without unnecessary emissions. The physical and chemical reactions taking place between the spark plug...

  17. Methanol with dimethyl ether ignition promotor as fuel for compression ignition engines

    SciTech Connect (OSTI)

    Brook, D.L.; Cipolat, D.; Rallis, C.J.

    1984-08-01

    Reduction of the world dependence upon crude oil necessitates the use of long term alternative fuels for internal combustion engines. Alcohols appear to offer a solution as in the short term they can be manufactured from natural gas and coal, while ultimately they may be produced from agricultural products. A fair measure of success has been achieved in using alcohols in spark ignition engines. However the more widely used compression ignition engines cannot utilize unmodified pure alcohols. The current techniques for using alcohol fuels in compression ignition engines all have a number of shortcomings. This paper describes a novel technique where an ignition promotor, dimethyl ether (DME), is used to increase the cetane rating of methanol. The systems particular advantage is that the DME can be catalyzed from the methanol base fuel, in situ. This fuel system matches the performance characteristics of diesel oil fuel.

  18. HEAVY QUARKS JETS

    E-Print Network [OSTI]

    Suzuki, M.

    2010-01-01

    i'iAsm Heavy Quark Jets iBirijets. Short-distance vs long-than a few wide angle sub-jets at to draw first skelton jet

  19. Weapons Activities/ Inertial Confinement Fusion Ignition

    E-Print Network [OSTI]

    , and reliability of the Nation's nuclear weapons without nuclear testing. The program provides this capability of the energy from a nuclear weapon is generated while in the high energy density (HED) state. High thermonuclear ignition to the national nuclear weapons program was one of the earliest motivations of the ICF

  20. Wildfires ignite debate on global warming

    E-Print Network [OSTI]

    Moritz, Max A.

    Wildfires ignite debate on global warming Astemperaturessoar. Is there a link with global warming? We have good reason to think so, and not taking the link seriously could have on climate change and global fire predictions last month, and I have been in my own media storm ever since

  1. Dark matter ignition of type Ia supernovae

    E-Print Network [OSTI]

    Bramante, Joseph

    2015-01-01

    Recent studies of low redshift type Ia supernovae (SNIa) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SNIa progenitors. We show that $0.1-10$ PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SNIa. We combine data on SNIa masses with data on the ages of SNIa-adjacent stars. This combination reveals a $ 3 \\sigma$ inverse correlation between SNIa masses and ignition ages, which could result from increased capture of dark matter in 1.4 versus 1.1 solar mass white dwarfs. Future studies of SNIa in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SNI...

  2. National Ignition Facility Title II Design Plan

    SciTech Connect (OSTI)

    Kumpan, S

    1997-03-01

    This National Ignition Facility (NIF) Title II Design Plan defines the work to be performed by the NIF Project Team between November 1996, when the U.S. Department of Energy (DOE) reviewed Title I design and authorized the initiation of Title H design and specific long-lead procurements, and September 1998, when Title 11 design will be completed.

  3. Impacts assessment for the National Ignition Facility

    SciTech Connect (OSTI)

    Bay Area Economics

    1996-12-01

    This report documents the economic and other impacts that will be created by the National Ignition Facility (NIF) construction and ongoing operation, as well as the impacts that may be created by new technologies that may be developed as a result of NIF development and operation.

  4. Turbulent flow in graphene

    E-Print Network [OSTI]

    Kumar S. Gupta; Siddhartha Sen

    2010-06-05

    We demonstrate the possibility of a turbulent flow of electrons in graphene in the hydrodynamic region, by calculating the corresponding turbulent probability density function. This is used to calculate the contribution of the turbulent flow to the conductivity within a quantum Boltzmann approach. The dependence of the conductivity on the system parameters arising from the turbulent flow is very different from that due to scattering.

  5. Quantum Gravity and Turbulence

    E-Print Network [OSTI]

    Vishnu Jejjala; Djordje Minic; Y. Jack Ng; Chia-Hsiung Tze

    2010-05-18

    We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.

  6. Chaotic Jets

    E-Print Network [OSTI]

    Xavier Leoncini; George M. Zaslavsky

    2006-02-21

    The problem of characterizing the origin of the non-Gaussian properties of transport resulting from Hamiltonian dynamics is addressed. For this purpose the notion of chaotic jet is revisited and leads to the definition of a diagnostic able to capture some singular properties of the dynamics. This diagnostic is applied successfully to the problem of advection of passive tracers in a flow generated by point vortices. We present and discuss this diagnostic as a result of which clues on the origin of anomalous transport in these systems emerge.

  7. Development and Benchmarking of a Hybrid PIC Code For Dense Plasmas and Fast Ignition

    SciTech Connect (OSTI)

    Witherspoon, F. Douglas; Welch, Dale R.; Thompson, John R.; MacFarlane, Joeseph J.; Phillips, Michael W.; Bruner, Nicki; Mostrom, Chris; Thoma, Carsten; Clark, R. E.; Bogatu, Nick; Kim, Jin-Soo; Galkin, Sergei; Golovkin, Igor E.; Woodruff, P. R.; Wu, Linchun; Messer, Sarah J.

    2014-05-20

    Radiation processes play an important role in the study of both fast ignition and other inertial confinement schemes, such as plasma jet driven magneto-inertial fusion, both in their effect on energy balance, and in generating diagnostic signals. In the latter case, warm and hot dense matter may be produced by the convergence of a plasma shell formed by the merging of an assembly of high Mach number plasma jets. This innovative approach has the potential advantage of creating matter of high energy densities in voluminous amount compared with high power lasers or particle beams. An important application of this technology is as a plasma liner for the flux compression of magnetized plasma to create ultra-high magnetic fields and burning plasmas. HyperV Technologies Corp. has been developing plasma jet accelerator technology in both coaxial and linear railgun geometries to produce plasma jets of sufficient mass, density, and velocity to create such imploding plasma liners. An enabling tool for the development of this technology is the ability to model the plasma dynamics, not only in the accelerators themselves, but also in the resulting magnetized target plasma and within the merging/interacting plasma jets during transport to the target. Welch pioneered numerical modeling of such plasmas (including for fast ignition) using the LSP simulation code. Lsp is an electromagnetic, parallelized, plasma simulation code under development since 1995. It has a number of innovative features making it uniquely suitable for modeling high energy density plasmas including a hybrid fluid model for electrons that allows electrons in dense plasmas to be modeled with a kinetic or fluid treatment as appropriate. In addition to in-house use at Voss Scientific, several groups carrying out research in Fast Ignition (LLNL, SNL, UCSD, AWE (UK), and Imperial College (UK)) also use LSP. A collaborative team consisting of HyperV Technologies Corp., Voss Scientific LLC, FAR-TECH, Inc., Prism Computational Sciences, Inc. and Advanced Energy Systems Inc. joined efforts to develop new physics and numerical models for LSP in several key areas to enhance the ability of LSP to model high energy density plasmas (HEDP). This final report details those efforts. Areas addressed in this research effort include: adding radiation transport to LSP, first in 2D and then fully 3D, extending the EMHD model to 3D, implementing more advanced radiation and electrode plasma boundary conditions, and installing more efficient implicit numerical algorithms to speed complex 2-D and 3-D computations. The new capabilities allow modeling of the dominant processes in high energy density plasmas, and further assist the development and optimization of plasma jet accelerators, with particular attention to MHD instabilities and plasma/wall interaction (based on physical models for ion drag friction and ablation/erosion of the electrodes). In the first funding cycle we implemented a solver for the radiation diffusion equation. To solve this equation in 2-D, we used finite-differencing and applied the parallelized sparse-matrix solvers in the PETSc library (Argonne National Laboratory) to the resulting system of equations. A database of the necessary coefficients for materials of interest was assembled using the PROPACEOS and ATBASE codes from Prism. The model was benchmarked against Prism's 1-D radiation hydrodynamics code HELIOS, and against experimental data obtained from HyperV's separately funded plasma jet accelerator development program. Work in the second funding cycle focused on extending the radiation diffusion model to full 3-D, continued development of the EMHD model, optimizing the direct-implicit model to speed up calculations, add in multiply ionized atoms, and improved the way boundary conditions are handled in LSP. These new LSP capabilities were then used, along with analytic calculations and Mach2 runs, to investigate plasma jet merging, plasma detachment and transport, restrike and advanced jet accelerator design. In addition, a strong linkage to diagnostic measureme

  8. The National Ignition Facility (NIF) and the National Ignition Campaign (NIC)

    SciTech Connect (OSTI)

    Moses, E

    2009-09-17

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and experiments studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). NIF construction was certified by the Department of Energy as complete on March 27, 2009. NIF, a 192-beam Nd:glass laser facility, will ultimately produce 1.8-MJ, 500-TW of 351-nm third-harmonic, ultraviolet light. On March 10, 2009, total 192-beam energy of 1.1 MJ was demonstrated; this is approximately 30 times more energy than ever produced in an ICF laser system. The principal goal of NIF is to achieve ignition of a deuterium-tritium (DT) fuel capsule and provide access to HED physics regimes needed for experiments related to national security, fusion energy and broader frontier scientific exploration. NIF experiments in support of indirect-drive ignition began in August 2009. These first experiments represent the next phase of the National Ignition Campaign (NIC). The NIC is a national effort to achieve fusion ignition and is coordinated through a detailed execution plan that includes the science, technology, and equipment. Equipment required for ignition experiments includes diagnostics, a cryogenic target manipulator, and user optics. Participants in this effort include LLNL, General Atomics (GA), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), and the University of Rochester Laboratory for Energetics (LLE). The primary goal for NIC is to have all of the equipment operational, integrated into the facility, and ready to begin a credible ignition campaign in 2010. With NIF now operational, the long-sought goal of achieving self-sustained nuclear fusion and energy gain in the laboratory is much closer to realization. Successful demonstration of ignition and net energy gain on NIF will be a major step towards demonstrating the feasibility of Inertial Fusion Energy (IFE) and will likely focus the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and Fast Ignition concepts. Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. The NIC will develop the full set of capabilities required to operate NIF as a major national and international user facility. A solicitation for NIF frontier science experiments is planned for summer 2009. This paper summarizes the design, performance, and status of NIF and plans for the NIF ignition experimental program. A brief summary of the overall NIF experimental program is also presented.

  9. Gas-flow measurements in a jet flame using cross-correlation of high speed particle-images

    SciTech Connect (OSTI)

    Shioji, Masahiro; Kawasaki, Kiyoshi; Kawanabe, Hiroshi; Ikegami, Makoto

    1999-07-01

    Time changes of a two-dimensional distribution of velocities in a methane jet flame and a nitrogen jet are measured by cross-correlation particle image velocimetry (PIV). The mean velocity and the intensity of turbulence are obtained and compared with those measured by HWA in order to ascertain the accuracy of PIV. Furthermore, the effect of combustion on turbulence characteristics is discussed based on the deformation of eddies with time change and distribution of time and spatial scales.

  10. Eddy fluxes in baroclinic turbulence

    E-Print Network [OSTI]

    Thompson, Andrew F.

    2006-01-01

    to a single meandering jet stream in each hemisphere. Theremarks regions of intense jet streams that reach speeds ofwithin in the Earth’s jet stream. In this way, zonal jets in

  11. Interaction of Jets with the ISM of Radio Galaxies

    E-Print Network [OSTI]

    R. S. Sutherland; G. V. Bicknell

    2007-07-25

    We present three dimensional simulations of the interaction of a light hypersonic jet with an inhomogeneous thermal and turbulently supported disk in an elliptical galaxy, including Radio and multi-band X-ray visualisations. These simulations are applicable to the GPS/CSS phase of some extragalactic radio sources. We identify four generic phases in the evolution of such a jet with the interstellar medium. The first is a `flood and channel'' phase, dominated by complex jet interactions with the dense cloudy medium close to the nucleus. A spherical, energy driven, bubble phase follows, where the bubble is larger than the disk scale, but the jet remains fully disrupted close to the nucleus. Then in a rapid, jet break--out phase, the jet breaks free of the last obstructing dense clouds, becomes collimated and pierces the more or less spherical bubble. In the final classical phase, the jet propagates in a momentum-dominated fashion similar to jets in single component hot haloes, leading to the classical jet -- cocoon -- bow-shock structure.

  12. Modeling of Jet-by-Jet Diffraction Dimitri Papamoschou

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    . Figure 1. Example of engine layout of Hybrid-Wing-Body airplane (Ref. 2). Research on jet-by-jetModeling of Jet-by-Jet Diffraction Dimitri Papamoschou The paper presents an analytical model for the prediction of jet-by-jet diffraction. The source jet is modeled as a radiating cylinder on which one can

  13. Multiple laser pulse ignition method and apparatus

    DOE Patents [OSTI]

    Early, J.W.

    1998-05-26

    Two or more laser light pulses with certain differing temporal lengths and peak pulse powers can be employed sequentially to regulate the rate and duration of laser energy delivery to fuel mixtures, thereby improving fuel ignition performance over a wide range of fuel parameters such as fuel/oxidizer ratios, fuel droplet size, number density and velocity within a fuel aerosol, and initial fuel temperatures. 18 figs.

  14. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    SciTech Connect (OSTI)

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  15. Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion

    SciTech Connect (OSTI)

    Choi, B.C.; Kim, K.N.; Chung, S.H.

    2009-02-15

    Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time. (author)

  16. Laser spark distribution and ignition system

    DOE Patents [OSTI]

    Woodruff, Steven (Morgantown, WV); McIntyre, Dustin L. (Morgantown, WV)

    2008-09-02

    A laser spark distribution and ignition system that reduces the high power optical requirements for use in a laser ignition and distribution system allowing for the use of optical fibers for delivering the low peak energy pumping pulses to a laser amplifier or laser oscillator. An optical distributor distributes and delivers optical pumping energy from an optical pumping source to multiple combustion chambers incorporating laser oscillators or laser amplifiers for inducing a laser spark within a combustion chamber. The optical distributor preferably includes a single rotating mirror or lens which deflects the optical pumping energy from the axis of rotation and into a plurality of distinct optical fibers each connected to a respective laser media or amplifier coupled to an associated combustion chamber. The laser spark generators preferably produce a high peak power laser spark, from a single low power pulse. The laser spark distribution and ignition system has application in natural gas fueled reciprocating engines, turbine combustors, explosives and laser induced breakdown spectroscopy diagnostic sensors.

  17. Jet-wall interaction effects on diesel combustion and soot formation.

    SciTech Connect (OSTI)

    Pickett, Lyle M.; Lopez, J. Javier

    2004-09-01

    The effects of wall interaction on combustion and soot formation processes of a diesel fuel jet were investigated in an optically-accessible constant-volume combustion vessel at experimental conditions typical of a diesel engine. At identical ambient and injector conditions, soot processes were studied in free jets, plane wall jets, and 'confined' wall jets (a box-shaped geometry simulating secondary interaction with adjacent walls and jets in an engine). The investigation showed that soot levels are significantly lower in a plane wall jet compared to a free jet. At some operating conditions, sooting free jets become soot-free as plane wall jets. Possible mechanisms to explain the reduced or delayed soot formation upon wall interaction include an increased fuel-air mixing rate and a wall-jet-cooling effect. However, in a confined-jet configuration, there is an opposite trend in soot formation. Jet confinement causes combustion gases to be redirected towards the incoming jet, causing the lift-off length to shorten and soot to increase. This effect can be avoided by ending fuel injection prior to the time of significant interaction with redirected combustion gases. For a fixed confined-wall geometry, an increase in ambient gas density delays jet interaction, allowing longer injection durations with no increase in soot. Jet interaction with redirected combustion products may also be avoided using reduced ambient oxygen concentration because of an increased ignition delay. Although simplified geometries were employed, the identification of important mechanisms affecting soot formation after the time of wall interaction is expected to be useful for understanding these processes in more complex and realistic diesel engine geometries.

  18. Ignitor with stable low-energy thermite igniting system

    DOE Patents [OSTI]

    Kelly, Michael D. (West Alexandria, OH); Munger, Alan C. (Miamisburg, OH)

    1991-02-05

    A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

  19. Role of metastable atoms in the propagation of atmospheric pressure dielectric barrier discharge jets

    SciTech Connect (OSTI)

    Li Qing; Zhu Ximing; Li Jiangtao; Pu Yikang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2010-02-15

    In the experiment of plasma jets generated in a tube dielectric barrier discharge configuration, three distinguishable modes, namely, laminar, transition, and turbulent jet modes, have been identified. Flows of helium, neon, and argon gases shared the hydrodynamic law when their plasma jets spraying into ambient air of atmospheric pressure and room temperature. Aiming to reveal the basic processes, we propose that plasma jet length is mainly determined by reactions involving metastable atoms. These processes are responsible for the variation in plasma jet length versus gas flow rate and working gas species. To investigate this proposal in detail, we have obtained three significant experimental results, i.e., (1) the plasma jet lengths of helium, neon, and argon are different; (2) the plasma jet length of krypton slightly changes with gas flow rate, with three modes indistinguishable; and (3) there are large differences between optical emission spectra of helium, neon, argon, and krypton flow gases. These observations are in good agreement with our proposal.

  20. Radiochemical tracers as a mix diagnostic for the ignition double...

    Office of Scientific and Technical Information (OSTI)

    for the ignition double-shell capsule One of the most important challenges confronting laser-driven capsule implosion experiments will be a quantitative evaluation of the...

  1. Improving the Efficiency of Spark Ignited, Stoichiometric Natural...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    2011 Utilizing the Rapid Ignition Region of HCCI to Attain > 60% BTE Compact, electro-hydraulic, variable valve actuation system providing variable lift, timing and duration to...

  2. Heavy Alcohols as a Fuel Blending Agent for Compression Ignition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Downsized SI Engines Using Alcohol DI for Knock Avoidance Characterization of Dual-Fuel Reactivity Controlled Compression Ignition (RCCI) Using Hydrated Ethanol and...

  3. STUDIES OF WALL FLAME QUENCHING AND HYDROCARBON EMISSIONS IN A MODEL SPARK IGNITION ENGINE

    E-Print Network [OSTI]

    Ishikawa, Nobuhiko

    2011-01-01

    ignition timing at 10 msec BTC, time interval 5 msec. flatignition, ignition timing at 12 BTC, time interval 5 msec .ignition timing at 25 msec BTC, time interval 5 msec . . . .

  4. Modeling the Fuel Spray and Combustion Process of the Ignition Quality Tester with KIVA-3V

    SciTech Connect (OSTI)

    Bogin, G. E. Jr.; DeFilippo, A.; Chen, J. Y.; Chin, G.; Luecke, J.; Ratcliff, M. A.; Zigler, B. T.; Dean, A. M.

    2010-05-01

    Discusses the use of KIVA-3V to develop a model that reproduces ignition behavior inside the Ignition Quality Tester, which measures the ignition delay of low-volatility fuels.

  5. Fossil turbulence and fossil turbulence waves can be dangerous

    E-Print Network [OSTI]

    Carl H Gibson

    2012-11-25

    Turbulence is defined as an eddy-like state of fluid motion where the inertial-vortex forces of the eddies are larger than any other forces that tend to damp the eddies out. By this definition, turbulence always cascades from small scales where vorticity is created to larger scales where turbulence fossilizes. Fossil turbulence is any perturbation in a hydrophysical field produced by turbulence that persists after the fluid is no longer turbulent at the scale of the perturbation. Fossil turbulence patterns and fossil turbulence waves preserve and propagate energy and information about previous turbulence. Ignorance of fossil turbulence properties can be dangerous. Examples include the Osama bin Laden helicopter crash and the Air France 447 Airbus crash, both unfairly blamed on the pilots. Observations support the proposed definitions, and suggest even direct numerical simulations of turbulence require caution.

  6. Top Jets at the LHC

    E-Print Network [OSTI]

    Almeida, L.G.

    2009-01-01

    Top Jets at the LHC Leandro G. Almeida, Seung J. Lee, GiladWIS/17/08-SEPT-DPP Top Jets at the LHC Leandro G. Almeidareconstructed as a single jet, a “top-jet”. The most basic “

  7. Particle Physics Phenomenology 8. QCD jets and jet algorithms

    E-Print Network [OSTI]

    Sjöstrand, Torbjörn

    Particle Physics Phenomenology 8. QCD jets and jet algorithms Torbj¨orn Sj¨ostrand Department rotationally symmetric. SppS (CERN): need to separate beam jets from highp ones. First solution: cone jets" infrared safe return to UA1 cone algorithm. Torbj¨orn Sj¨ostrand PPP 8: QCD jets and jet algorithms slide 2

  8. Low emissions compression ignited engine technology

    DOE Patents [OSTI]

    Coleman, Gerald N. (Dunlap, IL); Kilkenny, Jonathan P. (Peoria, IL); Fluga, Eric C. (Dunlap, IL); Duffy, Kevin P. (East Peoria, IL)

    2007-04-03

    A method and apparatus for operating a compression ignition engine having a cylinder wall, a piston, and a head defining a combustion chamber. The method and apparatus includes delivering fuel substantially uniformly into the combustion chamber, the fuel being dispersed throughout the combustion chamber and spaced from the cylinder wall, delivering an oxidant into the combustion chamber sufficient to support combustion at a first predetermined combustion duration, and delivering a diluent into the combustion chamber sufficient to change the first predetermined combustion duration to a second predetermined combustion duration different from the first predetermined combustion duration.

  9. National Ignition Facility | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory ofDid you notHeatMaRIEdioxide capture CSNational Ignition Facility Subscribe

  10. ATMOSPHERIC CIRCULATION OF BROWN DWARFS: JETS, VORTICES, AND TIME VARIABILITY

    SciTech Connect (OSTI)

    Zhang, Xi; Showman, Adam P.

    2014-06-10

    A variety of observational evidence demonstrates that brown dwarfs exhibit active atmospheric circulations. In this study we use a shallow-water model to investigate the global atmospheric dynamics in the stratified layer overlying the convective zone on these rapidly rotating objects. We show that the existence and properties of the atmospheric circulation crucially depend on key parameters including the energy injection rate and radiative timescale. Under conditions of strong internal heat flux and weak radiative dissipation, a banded flow pattern comprised of east-west jet streams spontaneously emerges from the interaction of atmospheric turbulence with the planetary rotation. In contrast, when the internal heat flux is weak and/or radiative dissipation is strong, turbulence injected into the atmosphere damps before it can self-organize into jets, leading to a flow dominated by transient eddies and isotropic turbulence instead. The simulation results are not very sensitive to the form of the forcing. Based on the location of the transition between jet-dominated and eddy-dominated regimes, we suggest that many brown dwarfs may exhibit atmospheric circulations dominated by eddies and turbulence (rather than jets) due to the strong radiative damping on these worlds, but a jet structure is also possible under some realistic conditions. Our simulated light curves capture important features from observed infrared light curves of brown dwarfs, including amplitude variations of a few percent and shapes that fluctuate between single-peak and multi-peak structures. More broadly, our work shows that the shallow-water system provides a useful tool to illuminate fundamental aspects of the dynamics on these worlds.

  11. Electron generation and transport in intense relativistic laser-plasma interactions relevant to fast ignition ICF

    E-Print Network [OSTI]

    Ma, Tammy Yee Wing

    2010-01-01

    1.1 Basics of Inertial Confinement Fusion with High Poweredguided fast-ignition inertial confinement fusion, Phys. Rev.Fast-Ignition Inertial Confinement Fusion,” Physical Review

  12. Ion Fast Ignition-Establishing a Scientific Basis for Inertial Fusion Energy --- Final Report

    SciTech Connect (OSTI)

    Stephens, Richard Burnite; Foord, Mark N.; Wei, Mingsheng; Beg, Farhat N.; Schumacher, Douglass W.

    2013-10-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional ?central hot spot? (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10?s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The compressed fuel is opaque to laser light. The ignition laser energy must be converted to a jet of energetic charged particles to deposit energy in the dense fuel. The original concept called for a spray of laser-generated hot electrons to deliver the energy; lack of ability to focus the electrons put great weight on minimizing the electron path. An alternative concept, proton-ignited FI, used those electrons as intermediaries to create a jet of protons that could be focused to the ignition spot from a more convenient distance. Our program focused on the generation and directing of the proton jet, and its transport toward the fuel, none of which were well understood at the onset of our program. We have developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to create a self-consistent understanding of the fundamental physics underlying these issues. Our strategy was to examine the new physics emerging as we added the complexity necessary to use proton beams in an inertial fusion energy (IFE) application. From the starting point of a proton beam accelerated from a flat, isolated foil, we 1) curved it to focus the beam, 2) attached the foil to a superstructure, 3) added a side sheath to protect it from the surrounding plasma, and finally 4) studied the proton beam behavior as it passed through a protective end cap into plasma. We built up, as we proceeded, a self-consistent picture of the quasi-neutral plasma jet that is the proton beam that, for the first time, included the role of the hot electrons in shaping the jet. Controlling them?through design of the accelerating surface and its connection to the surrounding superstructure?is critical; their uniform spread across the proton accelerating area is vital, but their presence in the jet opposes focus; their electron flow away from the acceleration area reduces conversion efficiency but can also increase focusing ability. The understanding emerging from our work and the improved simulation tools we have developed allow designing structures that optimize proton beams for focused heating. Our findings include: ? The achievable focus of proton beams is limited by the thermal pressure gradient in the laser-generated hot electrons that drive the process. This bending can be suppressed using a controlled flow of hot electrons along the surrounding cone wall, which induces a local transverse focusing sheath electric field. The resultant (vacuum-focused) spot can meet IFE requirements. ? Confinement of laser-generated electrons to the proton accelerating area can be achieved by supporting targets on thin struts. That increases laser-to-proton conversion energy by ~50%. As noted above, confinement should not be total; necessary hot-electron leakage into the surrounding superstructure for proton focusing can be controlled by with the strut width/number. ? Proton jets are further modified as they enter the fuel through the superstructure?s end cap. They can generate currents during that transit that further focus the proton beams. We developed a new ion stopping module for LSP code that properly accounted for changes in stopping power with ionization (e.g. temperature), and will be using it in future studies. The improved understanding, new experimental platforms, and the self-consistent modeling capability allow researchers a new ability to investigate the interaction of large ion currents with warm dense matter. That is of direct importance to the creation and investiga

  13. Development of nuclear diagnostics for the National Ignition Facility ,,invited...

    E-Print Network [OSTI]

    Development of nuclear diagnostics for the National Ignition Facility ,,invited... V. Yu. Glebov, D 87185 S. P. Padalino SUNY Geneseo, Geneseo, New York 14454 C. Horsfield Atomic Weapons Establishment of nuclear diagnostics in ICF experiments. In 2005, the suite of nuclear-ignition diagnostics for the NIF

  14. Multi-zone modelling of partially premixed low-temperature combustion in pilot-ignited natural-gas engines

    SciTech Connect (OSTI)

    Krishnan, S. R.; Srinivasan, K. K.

    2010-06-29

    Detailed results from a multi-zone phenomenological simulation of partially premixed advanced-injection low-pilot-ignited natural-gas low-temperature combustion are presented with a focus on early injection timings (the beginning of (pilot) injection (BOI)) and very small diesel quantities (2-3 per cent of total fuel energy). Combining several aspects of diesel and spark ignition engine combustion models, the closed-cycle simulation accounted for diesel autoignition, diesel spray combustion, and natural-gas combustion by premixed turbulent flame propagation. The cylinder contents were divided into an unburned zone, several pilot fuel zones (or 'packets') that modelled diesel evaporation and ignition, a flame zone for natural-gas combustion, and a burned zone. The simulation predicted the onset of ignition, cylinder pressures, and heat release rate profiles satisfactorily over a wide range of BOIs (20-60���° before top dead centre (before TDC)) but especially well at early BOIs. Strong coupling was observed between pilot spray combustion in the packets and premixed turbulent combustion in the flame zone and, therefore, the number of ignition centres (packets) profoundly affected flame combustion. The highest local peak temperatures (greater than 2000 K) were observed in the packets, while the flame zone was much cooler (about 1650 K), indicating that pilot diesel spray combustion is probably the dominant source of engine-out emissions of nitrogen oxide (NO x). Further, the 60���° before TDC BOI yielded the lowest average peak packet temperatures (about 1720 K) compared with the 20���° before TDC BOI (about 2480 K) and 40���° before TDC BOI (about 2700 K). These trends support experimental NO x trends, which showed the lowest NO x emissions for the 60���°, 20���°, and 40���° before TDC BOIs in that order. Parametric studies showed that increasing the intake charge temperature, pilot quantity, and natural-gas equivalence ratio all led to higher peak heat release rates and hotter packets but the pilot quantity and intake temperature affected the potential for NO x formation to a greater extent.

  15. Fully Developed Turbulent Mixing in an Annular Sector

    SciTech Connect (OSTI)

    Lim, Hyun-Kyung; Zhou, Yijie; de Almeida, Valmor F; Glimm, James G

    2014-01-01

    We review recent progress on the characterization of turbulent mixing fluid flow and relate these ideas to high-speed, two-phase Couette flow with application to mixing in a centrifugal contactor. The general ideas are more broadly applicable and have been applied to the study of Rayleigh-Taylor and Richtmyer-Meshkov fluid mixing, combustion in the engine of a scram jet and the analysis of inertial confinement pellet simulations.

  16. Variable valve timing in a homogenous charge compression ignition engine

    DOE Patents [OSTI]

    Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

    2004-08-03

    The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

  17. Stockpile Stewardship and the National Ignition Facility

    SciTech Connect (OSTI)

    Moses, E

    2012-01-04

    The National Ignition Facility (NIF), the world's most energetic laser system, is operational at Lawrence Livermore National Laboratory (LLNL). Since the completion of the construction project in March 2009, NIF has completed nearly 150 target experiments for the National Ignition Campaign (NIC), High Energy Density Stewardship Science (HEDSS) in the areas of radiation transport, material dynamics at high pressure in the solid state, as well as fundamental science and other national security missions. NIF capabilities and infrastructure are in place to support all of its missions with over 50 X-ray, optical and nuclear diagnostic systems and the ability to shoot cryogenic targets and DT layered capsules. NIF is now qualified for use of tritium and other special materials as well as to perform high yield experiments and classified experiments. DT implosions with record indirect-drive neutron yield of 4.5 x 10{sup 14} neutrons have been achieved. A series of 43 experiments were successfully executed over a 27-day period, demonstrating the ability to perform precise experiments in new regimes of interest to HEDSS. This talk will provide an update of the progress on the NIF capabilities, NIC accomplishments, as well as HEDSS and fundamental science experimental results and an update of the experimental plans for the coming year.

  18. National Ignition Facility project acquisition plan

    SciTech Connect (OSTI)

    Callaghan, R.W.

    1996-04-01

    The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility (NIF) Project. The scope of the plan describes the procurement activities and acquisition strategy for the following phases of the NIF Project, each of which receives either plant and capital equipment (PACE) or other project cost (OPC) funds: Title 1 and 2 design and Title 3 engineering (PACE); Optics manufacturing facilitization and pilot production (OPC); Convention facility construction (PACE); Procurement, installation, and acceptance testing of equipment (PACE); and Start-up (OPC). Activities that are part of the base Inertial Confinement Fusion (ICF) Program are not included in this plan. The University of California (UC), operating Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory, and Lockheed-Martin, which operates Sandia National Laboratory (SNL) and the University of Rochester Laboratory for Laser Energetics (UR-LLE), will conduct the acquisition of needed products and services in support of their assigned responsibilities within the NIF Project structure in accordance with their prime contracts with the Department of Energy (DOE). LLNL, designated as the lead Laboratory, will have responsibility for all procurements required for construction, installation, activation, and startup of the NIF.

  19. SCB ignition of pyrotechnics, thermites and intermetallics

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.; Grubelich, M.C.

    1996-09-01

    We investigated ignition of pyrotechnics, metal-fuel/metal-oxide compositions (thermites), and exothermic alloy compositions (intermetallics) using a semiconductor bridge (SCB). It was shown that these materials could be ignited at low energy levels with an appropriately designed SCB, proper loading density, and good thermal isolation. Materials tested included Al/CuO, B/BaCrO{sub 4}, TiH{sub 1.65}/KClO{sub 4}, Ti/KClO{sub 4}, Zr/BaCrO{sub 4}, Zr/CuO, Zr/Fe{sub 2}O{sub 3}, Zr/KClO{sub 4}, and 100-mesh Al/Pd. Firing set was a capacitor discharge unit with charge capacitors ranging from 3 to 20,000 {mu}F at charge voltages 5-50 V. Devices functioned a few miliseconds after onset of current pulse at input energies as low as 3 mJ. We also report on a thermite torch design.

  20. PBXN-9 Ignition Kinetics and Deflagration Rates

    SciTech Connect (OSTI)

    Glascoe, E; Maienschein, J; Burnham, A; Koerner, J; Hsu, P; Wemhoff, A

    2008-04-24

    The ignition kinetics and deflagration rates of PBXN-9 were measured using specially designed instruments at LLNL and compared with previous work on similar HMX based materials. Ignition kinetics were measured based on the One Dimensional Time-to-Explosion combined with ALE3D modeling. Results of these experiments indicate that PBXN-9 behaves much like other HMX based materials (i.e. LX-04, LX-07, LX-10 and PBX-9501) and the dominant factor in these experiments is the type of explosive, not the type of binder/plasticizer. In contrast, the deflagration behavior of PBXN-9 is quite different from similar high weight percent HMX based materials (i.e LX-10, LX-07 and PBX-9501). PBXN-9 burns in a laminar manner over the full pressure range studied (0-310 MPa) unlike LX-10, LX-07, and PBX-9501. The difference in deflagration behavior is attributed to the nature of the binder/plasticizer alone or in conjunction with the volume of binder present in PBXN-9.

  1. Four Lectures on Turbulent Combustion

    E-Print Network [OSTI]

    Peters, Norbert

    Four Lectures on Turbulent Combustion N. Peters Institut f¨ur Technische Mechanik RWTH Aachen Turbulent Combustion: Introduction and Overview 1 1.1 Moment Methods in Modeling Turbulence with Combustion and Velocity Scales . . . . . . . . . . . 11 1.4 Regimes in Premixed Turbulent Combustion

  2. Coherent Structures in Turbulent Flows: Experimental Studies on the Turbulence of Multiphase Plumes and Tidal Vortices 

    E-Print Network [OSTI]

    Bryant, Duncan Burnette

    2011-08-08

    stream_source_info BRYANT-DISSERTATION.pdf.txt stream_content_type text/plain stream_size 163756 Content-Encoding ISO-8859-1 stream_name BRYANT-DISSERTATION.pdf.txt Content-Type text/plain; charset=ISO-8859..., the turbulent energy spectra in inertial particle plumes followed the same modulation as the bubble plumes. PIV experiments from the tidal starting-jet vortices detail the influence of a finite channel length using identified vortice. The results show...

  3. A swirling jet under the influence of a coaxial flow

    SciTech Connect (OSTI)

    Giannadakis, A.; Perrakis, K.; Panidis, Th. [University of Patras, Department of Mechanical Engineering and Aeronautics, Laboratory of Applied Thermodynamics (Greece)

    2008-09-15

    The recirculating flow field generated by a swirling jet and a coaxial annular stream entering a pipe is investigated with the use of 2D-DPIV. Parametric change of inlet flow rates (constant tangential injection with change of annular flow and vice versa) is being considered in order to study the mean and turbulent flow field. A recirculation bubble stabilized close to the swirler exit is the dominating feature of the interaction between the inner swirling jet and the annular stream. Results are discussed in terms of bubble topology and dynamics on the basis of a modified Rossby number that appears to describe the trends of the complex flow field. (author)

  4. Experimental study on confined two-phase jets

    SciTech Connect (OSTI)

    Levy, Y.; Albagli, D. )

    1991-09-01

    The basic mixing phenomena in confined, coaxial, particle-laden turbulent flows are studied within the scope of ram combustor research activities. Cold-flow experiments in a relatively simple configuration of confined, coaxial two-phase jets provided both qualitative and quantitative insight on the multiphase mixing process. Pressure, tracer gas concentration, and two-phase velocity measurements revealed that unacceptably long ram combustors are needed for complete confined jet mixing. Comparison of the experimental results with a previous numerical simulation displayed a very good agreement, indicating the potential of the experimental facility for validation of computational parametric studies. 38 refs.

  5. Substructure of Boosted Jets

    E-Print Network [OSTI]

    Ehud Duchovni

    2013-05-21

    Jets with transverse energy of few TeV are becoming now common in LHC data. Most of these jets are produced by QCD processes and some from the collimated decay of highly boosted objects like W, Z, H0 and top-quark. The study of such QCD jets may shed light on QCD showering processes and the identification of the jets coming from decays may test the Standard Model under extreme conditions and may also provide the first hints for Physics Beyond the Standard Model. A short review of jet algorithms, Correction procedures for pile-up effects and commonly used substructure observables are described.

  6. Exploring the effect of fluid dynamics and kinetic mechanisms on n-heptane autoignition in transient jets

    SciTech Connect (OSTI)

    Viggiano, Annarita [Department of Environmental Engineering and Physics, University of Basilicata, viale dell'Ateneo Lucano 10, 85100 Potenza (Italy)

    2010-02-15

    The influence of physical parameters and of flow patterns on the prediction of n-heptane ignition dynamic in transient reacting n-heptane jets, in high pressure environment under laminar conditions, has been explored by using different kinetic mechanisms. Some preliminary transient laminar flamelet computations have been performed, thus showing that the sensitivity of the ignition time to strain rate depends on the kinetic mechanism used. Therefore, the structure of the reacting jet, in particular the localization of ignition spots, is investigated. The results show that, if the initial temperature of the reacting mixture is out of the intermediate range (800-1000 K) towards lower values, the fluid dynamics has an essential role. In this case, the ignition delay time is almost insensitive to the specific kinetic mechanism adopted, conversely it is severely shortened by increasing the streamwise velocity. The burning spot is located in the core of fuel roll-up, where low values of scalar dissipation rate occur. Nevertheless, the most reactive mixture fraction conditions are well predicted by chemical kinetics, as they are in good agreement with those computed for the one-dimensional diffusion layer. When the initial temperature of fuel and air is increased in the intermediate range, ignition is strongly dependent on the kinetic mechanism used. In these cases, the choice of an accurate chemical scheme is fundamental in order to obtain reliable results. (author)

  7. Kilohertz PIV/PLMS of low-gravity turbulent flames in a drop tower I.G. Boxx, C.A. Idicheria, N.T. Clemens(1)

    E-Print Network [OSTI]

    Clemens, Noel T.

    -flame in a crossflow (JFICF). The system developed represents a major advance in the state of the art of microgravity to examine a hydrogen jet-flame in a crossflow (momentum flux ratio of 7, Re = 900) under normal and low. INTRODUCTION The turbulent jet-flame in a crossflow (JFICF) is a flowfield of theoretical and applied

  8. Catalytic igniters and their use to ignite lean hydrogen-air mixtures

    DOE Patents [OSTI]

    McLean, William J. (Oakland, CA); Thorne, Lawrence R. (Livermore, CA); Volponi, Joanne V. (Livermore, CA)

    1988-01-01

    A catalytic igniter which can ignite a hydrogen-air mixture as lean as 5.5% hydrogen with induction times ranging from 20 s to 400 s, under conditions which may be present during a loss-of-liquid-coolant accident at a light water nuclear reactor comprises (a) a perforate catalytically active substrate, such as a platinum coated ceramic honeycomb or wire mesh screen, through which heated gases produced by oxidation of the mixture can freely flow and (b) a plurality of thin platinum wires mounted in a thermally conductive manner on the substrate and positioned thereon so as to be able to receive heat from the substrate and the heated gases while also in contact with unoxidized gases.

  9. Pre-ignition laser ablation of nanocomposite energetic materials

    SciTech Connect (OSTI)

    Stacy, S. C.; Massad, R. A.; Pantoya, M. L. [Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)] [Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

    2013-06-07

    Laser ignition of energetic material composites was studied for initiation with heating rates from 9.5 Multiplication-Sign 10{sup 4} to 1.7 Multiplication-Sign 10{sup 7} K/s. This is a unique heating rate regime for laser ignition studies because most studies employ either continuous wave CO{sub 2} lasers to provide thermal ignition or pulsed Nd:YAG lasers to provide shock ignition. In this study, aluminum (Al) and molybdenum trioxide (MoO{sub 3}) nanoparticle powders were pressed into consolidated pellets and ignited using a Nd:YAG laser (1064 nm wavelength) with varied pulse energy. Results show reduced ignition delay times corresponding to laser powers at the ablation threshold for the sample. Heating rate and absorption coefficient were determined from an axisymmetric heat transfer model. The model estimates absorption coefficients from 0.1 to 0.15 for consolidated pellets of Al + MoO{sub 3} at 1064 nm wavelength. Ablation resulted from fracturing caused by a rapid increase in thermal stress and slowed ignition of the pellet.

  10. Observations of Edge Turbulence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Edge Turbulence near the X-point of Alcator C-Mod APS-2007 (1) J.L. Terry, S.J. Zweben*, B. LaBombard, I. Cziegler, O. Grulke + , D.P. Stotler* MIT - Plasma Science and Fusion...

  11. Fuel quantity modulation in pilot ignited engines

    DOE Patents [OSTI]

    May, Andrew

    2006-05-16

    An engine system includes a first fuel regulator adapted to control an amount of a first fuel supplied to the engine, a second fuel regulator adapted to control an amount of a second fuel supplied to the engine concurrently with the first fuel being supplied to the engine, and a controller coupled to at least the second fuel regulator. The controller is adapted to determine the amount of the second fuel supplied to the engine in a relationship to the amount of the first fuel supplied to the engine to operate in igniting the first fuel at a specified time in steady state engine operation and adapted to determine the amount of the second fuel supplied to the engine in a manner different from the relationship at steady state engine operation in transient engine operation.

  12. Fast Camera Imaging of Hall Thruster Ignition

    SciTech Connect (OSTI)

    C.L. Ellison, Y. Raitses and N.J. Fisch

    2011-02-24

    Hall thrusters provide efficient space propulsion by electrostatic acceleration of ions. Rotating electron clouds in the thruster overcome the space charge limitations of other methods. Images of the thruster startup, taken with a fast camera, reveal a bright ionization period which settles into steady state operation over 50 ?s. The cathode introduces azimuthal asymmetry, which persists for about 30 ?s into the ignition. Plasma thrusters are used on satellites for repositioning, orbit correction and drag compensation. The advantage of plasma thrusters over conventional chemical thrusters is that the exhaust energies are not limited by chemical energy to about an electron volt. For xenon Hall thrusters, the ion exhaust velocity can be 15-20 km/s, compared to 5 km/s for a typical chemical thruster

  13. National Ignition Facility wet weather construction plan

    SciTech Connect (OSTI)

    Kugler, A N

    1998-01-01

    This report presents a wet weather construction plan for the National Ignition Facility (NIF) construction project. Construction of the NIF commenced in mid- 1997, and excavation of the site was completed in the fall. Preparations for placing concrete foundations began in the fall, and above normal rainfall is expected over the tinter. Heavy rainfall in late November impacted foundation construction, and a wet weather construction plan was determined to be needed. This wet weather constiction plan recommends a strategy, techniques and management practices to prepare and protect the site corn wet weather effects and allow construction work to proceed. It is intended that information in this plan be incorporated in the Stormwater Pollution Prevention Plan (SWPPP) as warranted.

  14. Fuel reactivity effects on the efficiency and operational window of dual-fuel compression ignition engines

    SciTech Connect (OSTI)

    Splitter, Derek A [ORNL; Reitz, Rolf [University of Wisconsin

    2014-01-01

    Fuel reactivity effects on the efficiency and operational window of dual-fuel compression ignition engines

  15. PHYSICAL REVIEW E 91, 013101 (2015) Integrated simulation approach for laser-driven fast ignition

    E-Print Network [OSTI]

    Wang, Wei Hua

    2015-01-01

    to realize laser fusion energy, the fast ignition (FI) scheme has attracted significant attention since

  16. Hydrogen-assisted catalytic ignition characteristics of different fuels

    SciTech Connect (OSTI)

    Zhong, Bei-Jing; Yang, Fan; Yang, Qing-Tao

    2010-10-15

    Hydrogen-assisted catalytic ignition characteristics of methane (CH{sub 4}), n-butane (n-C{sub 4}H{sub 10}) and dimethyl ether (DME) were studied experimentally in a Pt-coated monolith catalytic reactor. It is concluded that DME has the lowest catalytic ignition temperature and the least required H{sub 2} flow, while CH{sub 4} has the highest catalytic ignition temperature and the highest required H{sub 2} flow among the three fuels. (author)

  17. Distributed ignition method and apparatus for a combustion engine

    DOE Patents [OSTI]

    Willi, Martin L.; Bailey, Brett M.; Fiveland, Scott B.; Gong, Weidong

    2006-03-07

    A method and apparatus for operating an internal combustion engine is provided. The method comprises the steps of introducing a primary fuel into a main combustion chamber of the engine, introducing a pilot fuel into the main combustion chamber of the engine, determining an operating load of the engine, determining a desired spark plug ignition timing based on the engine operating load, and igniting the primary fuel and pilot fuel with a spark plug at the desired spark plug ignition timing. The method is characterized in that the octane number of the pilot fuel is lower than the octane number of the primary fuel.

  18. The National Ignition Facility: The Path to Ignition, High Energy Density Science and Inertial Fusion Energy

    SciTech Connect (OSTI)

    Moses, E

    2011-03-25

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is a Nd:Glass laser facility capable of producing 1.8 MJ and 500 TW of ultraviolet light. This world's most energetic laser system is now operational with the goals of achieving thermonuclear burn in the laboratory and exploring the behavior of matter at extreme temperatures and energy densities. By concentrating the energy from its 192 extremely energetic laser beams into a mm{sup 3}-sized target, NIF can produce temperatures above 100 million K, densities of 1,000 g/cm{sup 3}, and pressures 100 billion times atmospheric pressure - conditions that have never been created in a laboratory and emulate those in the interiors of planetary and stellar environments. On September 29, 2010, NIF performed the first integrated ignition experiment which demonstrated the successful coordination of the laser, the cryogenic target system, the array of diagnostics and the infrastructure required for ignition. Many more experiments have been completed since. In light of this strong progress, the U.S. and the international communities are examining the implication of achieving ignition on NIF for inertial fusion energy (IFE). A laser-based IFE power plant will require a repetition rate of 10-20 Hz and a 10% electrical-optical efficiency laser, as well as further advances in large-scale target fabrication, target injection and tracking, and other supporting technologies. These capabilities could lead to a prototype IFE demonstration plant in 10- to 15-years. LLNL, in partnership with other institutions, is developing a Laser Inertial Fusion Energy (LIFE) baseline design and examining various technology choices for LIFE power plant This paper will describe the unprecedented experimental capabilities of the NIF, the results achieved so far on the path toward ignition, the start of fundamental science experiments and plans to transition NIF to an international user facility providing access to researchers around the world. The paper will conclude with a discussion of LIFE, its development path and potential to enable a carbon-free clean energy future.

  19. PHYSICS OF FLUIDS 25, 055107 (2013) Turbulent premixed combustion in V-shaped flames

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2013-01-01

    industrial combustion systems such as, stationary gas turbines, lean premixed and prevaporized jet engines for simulating combustion in gas turbine engines. Second, although a large body of research has been devotedPHYSICS OF FLUIDS 25, 055107 (2013) Turbulent premixed combustion in V-shaped flames

  20. Diffusive radiation in one-dimensional Langmuir turbulence G. D. Fleishman1

    E-Print Network [OSTI]

    -dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular sensi- tively on the angle between the particle velocity and electric field direction. The radiation as gamma-ray bursts and collimated jets. DOI: 10.1103/PhysRevE.76.017401 PACS number s : 52.25.Os, 52.35.Ra

  1. LES/PDF based modeling of sootturbulence interactions in turbulent flames

    E-Print Network [OSTI]

    Raman, Venkat

    number density function. This LES/PDF approach is then used to simulate a turbulent natural gas jet strong correlation between the gas phase composition and soot moments. Ó 2012 The Combustion Institute and the gas-phase composition are often neglected. In this case, the PDF is written as the product of the mar

  2. Modeling shock unsteadiness in shock/turbulence interaction Krishnendu Sinha*, Krishnan Mahesh and Graham V. Candler

    E-Print Network [OSTI]

    Mahesh, Krishnan

    flows, e.g. deflected control surfaces of high-speed vehicles and inlet of scram jet engines. Shock and Graham V. Candler Aerospace Engineering and Mechanics & Army HPC Research Center University of Minnesota and Astro- nautics, Inc. with permission. Engineering prediction of shock/turbulence inter- action relies

  3. Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels

    SciTech Connect (OSTI)

    Seitzman, Jerry; Lieuwen, Timothy

    2014-09-30

    This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide evidence that the leading points model can provide useful predictions of turbulent flame speed over a wide range of operating conditions and flow geometries.

  4. Diffusive radiation in Langmuir turbulence produced by jet shocks

    E-Print Network [OSTI]

    Fleishman, Gregory D

    2007-01-01

    Anisotropic distributions of charged particles including two-stream distributions give rise to generation of either stochastic electric fields (in the form of Langmuir waves, Buneman instability) or random quasi-static magnetic fields (Weibel and filamentation instabilities) or both. These two-stream instabilities are known to play a key role in collisionless shock formation, shock-shock interactions, and shock-induced electromagnetic emission. This paper applies the general non-perturbative stochastic theory of radiation to study electromagnetic emission produced by relativistic particles, which random walk in the stochastic electric fields of the Langmuir waves. This analysis takes into account the cumulative effect of uncorrelated Langmuir waves on the radiating particle trajectory giving rise to angular diffusion of the particle, which eventually modifies the corresponding radiation spectra. We demonstrate that the radiative process considered is probably relevant for emission produced in various kinds of...

  5. CONTROL OF COHERENT STRUCTURE IN COAXIAL SWIRLING TURBULENT JETS

    E-Print Network [OSTI]

    Lee, Wonjoong

    2008-01-01

    mechanical excitation device are designed and fabricated for the low speed and plain perturbations. The major system components consist of concentric subsonic nozzles, swirl generators, and the excitation devices with straight lobes. The experiments...

  6. Quantitative Imaging of Multi-component Turbulent Jets

    E-Print Network [OSTI]

    Victoria, University of

    to emulate releases in which leak geometry is circular. Effects of buoyancy, crossflow and adjacent surfaces................................................................................................3 1.2.2 Crossflow

  7. Jet studies with STAR at RHIC: jet algorithms, jet shapes, jets in AA

    E-Print Network [OSTI]

    Jan Kapitan; for the STAR Collaboration

    2011-11-08

    Hard scattered partons are predicted to be well calibrated probes of the hot and dense medium produced in heavy ion collisions. Interactions of these partons with the medium w ill result in modifications of internal jet structure in Au+Au events compared to that observed in the p+p/d+Au reference. Full jet reconstruction is a promising tool to measu re these effects without the significant biases present in measurements with high-$\\pT$ hadrons. One of the most significant challenges for jet reconstruction in the heavy ion environment comes from the correct characterization of the background fluctuations. The jet mome ntum irresolution due to background fluctuations has to be understood in order to recover the correct jet spectrum. Recent progress in jet reconstruction methodology is discu ssed, as well as recent measurements from p+p, d+Au and Au+Au collisions at $\\sqrt{s_\\mathrm{NN}}=200 \\gev$.

  8. Reconstructed Jets at RHIC

    E-Print Network [OSTI]

    Sevil Salur

    2010-04-30

    To precisely measure jets over a large background such as pile up in high luminosity p+p collisions at LHC, a new generation of jet reconstruction algorithms is developed. These algorithms are also applicable to reconstruct jets in the heavy ion environment where large event multiplicities are produced. Energy loss in the medium created in heavy ion collisions are already observed indirectly via inclusive hadron distributions and di-hadron correlations. Jets can be used to study this energy loss in detail with reduced biases. We review the latest results on jet-medium interactions as seen in A+A collisions at RHIC, focusing on the recent progress on jet reconstruction in heavy ion collisions.

  9. Turbulent flame speeds and NOx kinetics of HHC fuels with contaminants and high dilution levels

    SciTech Connect (OSTI)

    Petersen, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankar; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Aul, Christopher; Petersen, Eric

    2012-09-30

    This progress report documents the second year of the project, from October 1, 2011 through September 30, 2012. Characterization of the new turbulent flame speed vessel design was completed. Turbulence statistics of three impellers with different geometric features were measured using particle image velocimetry inside a Plexiglas model (~1:1 scale) of a cylindrical flame speed vessel (30.5 cm ID × 35.6 cm L). With four impellers arranged in a central-symmetric configuration, turbulence intensities between 1.2 and 1.7 m/s with negligible mean flow (0.1u´) were attained at the lowest fan speeds. Acceptable ranges for homogeneity and isotropy ratios of the velocity fields were set within a narrow bandwidth near unity (0.9-1.1). Homogeneity ratios were unaffected by changes to the impeller geometry, and the prototype with the higher number of blades caused the flow to become anisotropic. The integral length scale of the flow fields varied between 27 and 20 mm, which correlates well with those typically observed inside a gas turbine combustor. The mechanism to independently vary the intensity level and the integral length scale was established, where turbulence intensity level was dependent on the rotational speed of the fan, and the integral length scale decreased with increasing blade pitch angle. Ignition delay times of H?/O? mixtures highly diluted with Ar and doped with various amounts of N?O (100, 400, 1600, 3200 ppm) were measured in a shock tube behind reflected shock waves over a wide range of temperatures (940-1675 K). The pressure range investigated during this work (around 1.6, 13, and 30 atm) allows studying the effect of N?O on hydrogen ignition at pressure conditions that have never been heretofore investigated. Ignition delay times were decreased when N?O was added to the mixture only for the higher nitrous oxide concentrations, and some changes in the activation energy were also observed at 1.5 and 30 atm. When it occurred, the decrease in the ignition delay time was proportional to the amount of N?O added and depended on pressure and temperature conditions. A detailed chemical kinetics model was developed using kinetic mechanisms from the literature. This model predicts well the experimental data obtained during this study and from the literature. The chemical analysis using this model showed that the decrease in the ignition delay time was mainly due to the reaction N?O +M ? N? + O +M which provides O atoms to strengthen the channel O + H? ? OH + H. Ignition delay times have been measured behind reflected shock waves at 1.5, 12 and 30 atm for a mixture representative of a syngas produced from biomass (0.29659% CO / 0.29659% H? / 0.15748% CO? / 0.08924% CH? / 0.20997% H?O / 0.95013% O? in 98% Ar (mol.%)) and for the same biomass-derived syngas mixture doped with 200 ppm of NH?. The importance of the various constituents on the ignition delay time was investigated by comparing the results with data from various baseline mixtures (H?/O?/Ar, H?/CO/O?/Ar and H?/CO/O?/Ar with one of the other constituent of the syngas (i.e. CO?, H?O, CH? or NH?)). The equivalence ratio was set to 0.5 during this study. Several recent detailed kinetics mechanisms from the literature were computed against these data, with fair agreement. Results showed that the mixture composition can have an important effect on the ignition delay time, with most of the effect being due to CH? addition through the reaction CH?+OH?CH?+H?O. The ammonia impurity had very little effect on the ignition delay time over the range of conditions studied.

  10. A spray-suppression model for turbulent combustion

    SciTech Connect (OSTI)

    DESJARDIN,PAUL E.; TIESZEN,SHELDON R.; GRITZO,LOUIS A.

    2000-02-14

    A spray-suppression model that captures the effects of liquid suppressant on a turbulent combusting flow is developed and applied to a turbulent diffusion flame with water spray suppression. The spray submodel is based on a stochastic separated flow approach that accounts for the transport and evaporation of liquid droplets. Flame extinguishment is accounted for by using a perfectly stirred reactor (PSR) submodel of turbulent combustion. PSR pre-calculations of flame extinction times are determined using CHEMKIN and are compared to local turbulent time scales of the flow to determine if local flame extinguishment has occurred. The PSR flame extinguishment and spray submodels are incorporated into Sandia's flow fire simulation code, VULCAN, and cases are run for the water spray suppression studies of McCaffrey for turbulent hydrogen-air jet diffusion flames. Predictions of flame temperature decrease and suppression efficiency are compared to experimental data as a function of water mass loading using three assumed values of drop sizes. The results show that the suppression efficiency is highly dependent on the initial droplet size for a given mass loading. A predicted optimal suppression efficiency was observed for the smallest class of droplets while the larger drops show increasing suppression efficiency with increasing mass loading for the range of mass loadings considered. Qualitative agreement to the experiment of suppression efficiency is encouraging, however quantitative agreement is limited due to the uncertainties in the boundary conditions of the experimental data for the water spray.

  11. High Fidelity Modeling of Premixed Charge Compression Ignition Engines

    Broader source: Energy.gov [DOE]

    Most accurate and detailed chemical kinetic models for fuels of practical interest to engine manufacturers and fuels developers are applied for high fidelity engine analysis of premixed charge compression ignition engines.

  12. On the Piloted Ignition of Solid Fuels in Spacecraft Environments

    E-Print Network [OSTI]

    Fereres-Rapoport, Sonya M.

    2011-01-01

    Gpyro- A Generalized Pyrolysis Model for Combustible Solids:Analytical and Applied Pyrolysis Vol. 71:2 (2004) pp. 569–Orientation and Altitude on Pyrolysis and Ignition of Wood”,

  13. Relativistic electron beam transport for fast ignition relevant scenarios

    E-Print Network [OSTI]

    Cottrill, Larissa A

    2009-01-01

    A crucial issue surrounding the feasibility of fast ignition, an alternative inertial confinement fusion scheme, is the ability to efficiently couple energy from an incident short-pulse laser to a high-density, pre-compressed ...

  14. Frictionally induced ignition processes in drop and skid tests

    SciTech Connect (OSTI)

    Dickson, Peter [Los Alamos National Laboratory; Parker, Gary [Los Alamos National Laboratory; Novak, Alan [Los Alamos National Laboratory

    2010-01-01

    The standard LANL/Pantex drop and skid tests rely on subjective assessment of reaction violence to quantify the response of the charge, and completely miss nonpropagating hot-spot ignition sites. Additionally, large variations in test results have been observed, which we propose is due to a misunderstanding of the basic physical processes that lead to threshold ignition in these tests. The tests have been redesigned to provide control of these mechanisms and to permit direct observation of hot spots at the impact site, allowing us to follow the progression of the outcome as the drop height and ignition source density are varied. The results confirm that frictional interactions between high-melting-point solids are the dominant ignition mechanism, not just at the threshold, but in fact at all realistic drop heights.

  15. QCD and Jet Physics

    E-Print Network [OSTI]

    B R Webber

    1994-10-12

    The current status of the QCD coupling constant $\\alpha_S$ and experimental and theoretical studies of hadronic jets are reviewed.

  16. Jets in QCD

    SciTech Connect (OSTI)

    Seymour, M.H.

    1996-02-01

    Many analyses at the collider utilize the hadronic jets that are the footprints of QCD partons. These are used both to study the QCD processes themselves and increasingly as tools to study other physics, for example top mass reconstruction. However, jets are not fundamental degrees of freedom in the theory, so we need an {ital operational} {ital jet} {ital definition} and {ital reliable} {ital methods} {ital to} {ital calculate} {ital their} {ital properties}. This talk covers both of these important areas of jet physics. {copyright} {ital 1996 American Institute of Physics.}

  17. Interpretation of extragalactic jets

    SciTech Connect (OSTI)

    Norman, M.L.

    1985-01-01

    The nature of extragalatic radio jets is modeled. The basic hypothesis of these models is that extragalatic jets are outflows of matter which can be described within the framework of fluid dynamics and that the outflows are essentially continuous. The discussion is limited to the interpretation of large-scale (i.e., kiloparsec-scale) jets. The central problem is to infer the physical parameters of the jets from observed distributions of total and polarized intensity and angle of polarization as a function of frequency. 60 refs., 6 figs.

  18. Ignition technique for an in situ oil shale retort

    DOE Patents [OSTI]

    Cha, Chang Y. (Golden, CO)

    1983-01-01

    A generally flat combustion zone is formed across the entire horizontal cross-section of a fragmented permeable mass of formation particles formed in an in situ oil shale retort. The flat combustion zone is formed by either sequentially igniting regions of the surface of the fragmented permeable mass at successively lower elevations or by igniting the entire surface of the fragmented permeable mass and controlling the rate of advance of various portions of the combustion zone.

  19. Ignition and burn of a small magnetized fuel target

    SciTech Connect (OSTI)

    Kirkpatrick, Ronald C.

    2012-06-01

    The crucial step for inertial confinement fusion (ICF) is ignition, which leads to sufficiently high gain to enable design of a power producing system. Thus far, this step has not been demonstrated. Magnetized targets may provide an alternative path to ignition. In addition, the 1-D calculations presented here suggest that this approach may provide the gain and other characteristics needed for a practical fusion reactor.

  20. Gasoline Engine Economy as Affected by the Time of Ignition

    E-Print Network [OSTI]

    Hopkins, George Jay

    1907-01-01

    variables¡— speed, load, point of ignition, mixture and jacket temperature. Considering any three of these five fixed, the other two will be inter-dependent. In view of this sensitiveness of one variable to changes of any other, it is fortunately... variables¡— speed, load, point of ignition, mixture and jacket temperature. Considering any three of these five fixed, the other two will be inter-dependent. In view of this sensitiveness of one variable to changes of any other, it is fortunately...

  1. Taming jets in magnetised fluids

    E-Print Network [OSTI]

    Kosuga, Yusuke; Brummell, Nicholas

    2010-01-01

    Down right: Cancellation of stresses and quenching of Jets.to Reynolds stress driven jets, since both ?ux expulsion andTaming Jets in magnetized ?uids Y. Kosuga 1 and N. H.

  2. Target Diagnostics Supports NIF's Path to Ignition

    SciTech Connect (OSTI)

    Shelton, R

    2011-12-07

    The physics requirements derived from the National Ignition Facility (NIF) experimental campaigns are leading to a wide variety of target diagnostics. Software development for the control and analysis of these diagnostics is included in the NIF Integrated Computer Control System, Diagnostic Control System and Data Visualization. These projects implement the configuration, controls, data analysis and visual representation of most of these diagnostics. To date, over 40 target diagnostics have been developed to support NIF experiments. In 2011 diagnostics were developed or enhanced to measure Ignition performance in a high neutron yield environment. Performance is optimized around four key variables: Adiabat (a) which is the strength and timing of four shocks delivered to the target, Velocity (V) of the imploding target, Mix (M) is the uniformity of the burn, and the Shape (S) of the imploding Deuterium Tritium (DT) hot spot. The diagnostics used to measure each of these parameters is shown in figure 1. Adiabat is measured using the Velocity Interferometer System for Any Reflector (VISAR) diagnostic consisting of three streak cameras. To provide for more accurate adiabat measurements the VISAR streak cameras were enhanced in FY11 with a ten comb fiducial signal controller to allow for post shot correction of the streak camera sweep non-linearity. Mix is measured by the Neutron Time of Flight (NTOF) and Radiochemical Analysis of Gaseous Samples (RAGS) diagnostics. To accommodate high neutron yield shots, NTOF diagnostic controls are being modified to use Mach Zehnder interferometer signals to allow the digitizers to be moved from near the target chamber to the neutron shielded diagnostic mezzanine. In December 2011 the first phase of RAGS diagnostic commissioning will be completed. This diagnostic will analyze the tracers that are added to NIF target capsules that undergo nuclear reactions during the shot. These gases are collected and purified for nuclear counting by the RAGS system. Three new instrument controllers were developed and commissioned to support this diagnostic. A residual-gas analyzer (RGA) instrument measures the gas content at various points in the system. The Digital Gamma Spectrometer instrument measures the radiological spectrum of the decaying gas isotopes. A final instrument controller was developed to interface to a PLC based Gas collection system. In order to support the implosion velocity measurements an additional Gated X-ray Detector (GXD) diagnostic was tested and commissioned. This third GXD views the target through a slit contained in its snout and allows the other GXD diagnostics to be used for measuring the shape on the same shot. In order to measure the implosion shape in a high neutron environment, Actide Readout In A Neutron Environment (ARIANE) and Neutron Imaging (NI) diagnostics were commissioned. The controls for ARIANE, a fixed port gated x-ray imager, contain a neutron shielded camera and micro channel plate pulser with its neutron sensitive electronics located in the diagnostic mezzanine. The NI diagnostic is composed of two Spectral Instruments SI-1000 cameras located 20M from the target and provides neutron images of the DT hot spot for high yield shots. The development and commissioning of these new or enhanced diagnostics in FY11 have provided meaningful insight that facilitates the optimization of the four key Ignition variables. In FY12 they will be adding three new diagnostics and enhancing four existing diagnostics in support of the continuing optimization series of campaigns.

  3. CORONA DISCHARGE IGNITION FOR ADVANCED STATIONARY NATURAL GAS ENGINES

    SciTech Connect (OSTI)

    Dr. Paul D. Ronney

    2003-09-12

    An ignition source was constructed that is capable of producing a pulsed corona discharge for the purpose of igniting mixtures in a test chamber. This corona generator is adaptable for use as the ignition source for one cylinder on a test engine. The first tests were performed in a cylindrical shaped chamber to study the characteristics of the corona and analyze various electrode geometries. Next a test chamber was constructed that closely represented the dimensions of the combustion chamber of the test engine at USC. Combustion tests were performed in this chamber and various electrode diameters and geometries were tested. The data acquisition and control system hardware for the USC engine lab was updated with new equipment. New software was also developed to perform the engine control and data acquisition functions. Work is underway to design a corona electrode that will fit in the new test engine and be capable igniting the mixture in one cylinder at first and eventually in all four cylinders. A test engine was purchased for the project that has two spark plug ports per cylinder. With this configuration it will be possible to switch between corona ignition and conventional spark plug ignition without making any mechanical modifications.

  4. Multidimensional turbulence spectra -identifying properties of turbulent structures

    E-Print Network [OSTI]

    Kevlahan, Nicholas

    Sweden 2 Department of Mathematics and Statistics, McMaster University, Hamilton L8S 4K1, Canada * E turbulent structures are presented. Results from analysis of the turbulent kinetic energy in turbulent energy associated with a coherent vortex defined using different vortex identification methods

  5. Studies of the effects of curvature on dilution jet mixing

    SciTech Connect (OSTI)

    Holdeman, J.D.; Srinivasan, Ram: Reynolds, R.S.; White, C.D. Allied-Signal Aerospace Co., Phoenix, AZ )

    1992-02-01

    An analytical program was conducted using both three-dimensional numerical and empirical models to investigate the effects of transition liner curvature on the mixing of jets injected into a confined crossflow. The numerical code is of the TEACH type with hybrid numerics; it uses the power-law and SIMPLER algorithms, an orthogonal curvilinear coordinate system, and an algebraic Reynolds stress turbulence model. From the results of the numerical calculations, an existing empirical model for the temperature field downstream of single and multiple rows of jets injected into a straight rectangular duct was extended to model the effects of curvature. Temperature distributions, calculated with both the numerical and empirical models, are presented to show the effects of radius of curvature and inner and outer wall injection for single and opposed rows of cool dilution jets injected into a hot mainstream flow. 27 refs.

  6. Experimental studies on the group ignition of a cloud of coal particles: Volume 2, Pyrolysis and ignition modeling

    SciTech Connect (OSTI)

    Annamalai, K.; Ryan, W.

    1992-01-01

    The primary objectives of this work are to formulate a model to simulate transient coal pyrolysis, ignition, and combustion of a cloud of coal particles and to compare results of the program with those reported in the literature elsewhere.

  7. Quantum ghost imaging through turbulence

    E-Print Network [OSTI]

    Dixon, P. Ben

    We investigate the effect of turbulence on quantum ghost imaging. We use entangled photons and demonstrate that for a specific experimental configuration the effect of turbulence can be greatly diminished. By decoupling ...

  8. QCD Jets and Parton Showers

    E-Print Network [OSTI]

    Bryan R. Webber

    2010-09-29

    I discuss the calculation of QCD jet rates in e+e- annihilation as a testing ground for parton shower simulations and jet finding algorithms.

  9. Theory of hydro-equivalent ignition for inertial fusion and its applications to OMEGA and the National Ignition Facility

    SciTech Connect (OSTI)

    Nora, R.; Betti, R.; Bose, A.; Woo, K. M.; Christopherson, A. R.; Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Fusion Science Center, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and/or Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Anderson, K. S.; Shvydky, A.; Marozas, J. A.; Collins, T. J. B.; Radha, P. B.; Hu, S. X.; Epstein, R.; Marshall, F. J.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); McCrory, R. L. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and/or Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

    2014-05-15

    The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements for cryogenic implosion experiments on the Omega Laser Facility. The theory of hydrodynamic similarity is developed in both one and two dimensions and tested using multimode hydrodynamic simulations with the hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] of hydro-equivalent implosions (implosions with the same implosion velocity, adiabat, and laser intensity). The theory is used to scale the performance of direct-drive OMEGA implosions to the National Ignition Facility (NIF) energy scales and determine the requirements for demonstrating hydro-equivalent ignition on OMEGA. Hydro-equivalent ignition on OMEGA is represented by a cryogenic implosion that would scale to ignition on the NIF at 1.8?MJ of laser energy symmetrically illuminating the target. It is found that a reasonable combination of neutron yield and areal density for OMEGA hydro-equivalent ignition is 3 to 6?×?10{sup 13} and ?0.3?g/cm{sup 2}, respectively, depending on the level of laser imprinting. This performance has not yet been achieved on OMEGA.

  10. The effects of obstacle geometry on jet mixing in releases of silane 

    E-Print Network [OSTI]

    Sposato, Christina F

    2000-01-01

    Releases of silane into air and the effects of obstacles were modeled with the Computational Fluid Dynamics (CFD) code, FLUENT. First the CFD code simulated the release of a free turbulent jet of silane into air to assure that the code agreed...

  11. The National Ignition Facility (NIF) A Path to Fusion Energy

    SciTech Connect (OSTI)

    Moses, E

    2006-11-27

    Fusion energy has long been considered a promising clean, nearly inexhaustible source of energy. Power production by fusion micro-explosions of inertial confinement fusion (ICF) targets has been a long term research goal since the invention of the first laser in 1960. The NIF is poised to take the next important step in the journey by beginning experiments researching ICF ignition. Ignition on NIF will be the culmination of over thirty years of ICF research on high-powered laser systems such as the Nova laser at LLNL and the OMEGA laser at the University of Rochester as well as smaller systems around the world. NIF is a 192 beam Nd-glass laser facility at LLNL that is more than 90% complete. The first cluster of 48 beams is operational in the laser bay, the second cluster is now being commissioned, and the beam path to the target chamber is being installed. The Project will be completed in 2009 and ignition experiments will start in 2010. When completed NIF will produce up to 1.8 MJ of 0.35 {micro}m light in highly shaped pulses required for ignition. It will have beam stability and control to higher precision than any other laser fusion facility. Experiments using one of the beams of NIF have demonstrated that NIF can meet its beam performance goals. The National Ignition Campaign (NIC) has been established to manage the ignition effort on NIF. NIC has all of the research and development required to execute the ignition plan and to develop NIF into a fully operational facility. NIF will explore the ignition space, including direct drive, 2{omega} ignition, and fast ignition, to optimize target efficiency for developing fusion as an energy source. In addition to efficient target performance, fusion energy requires significant advances in high repetition rate lasers and fusion reactor technology. The Mercury laser at LLNL is a high repetition rate Nd-glass laser for fusion energy driver development. Mercury uses state-o-the art technology such as ceramic laser slabs and light diode pumping for improved efficiency and thermal management. Progress in NIF, NIC, Mercury, and the path forward for fusion energy will be presented.

  12. Structure and Mixing Characterization of Variable Density Transverse Jet Flows

    E-Print Network [OSTI]

    Gevorkyan, Levon

    2015-01-01

    4 Transverse Jet Mixing . . . . . . . . . . . . . . . . . .Jet TrajectoryTransverse Jet Structure and

  13. Nonaxisymmetric Poynting Jets

    E-Print Network [OSTI]

    Samuel E. Gralla; Ted Jacobson

    2015-07-29

    The relativistic plasma jets from a misaligned black hole-accretion disk system will not be axially symmetric. Here we analyze nonaxisymmetric, stationary, translation invariant jets in the force-free approximation where the field energy dominates the particle energy. We derive a stream equation for these configurations involving the flux function $\\psi$ for the transverse magnetic field, the linear velocity $v(\\psi)$ of field lines along the jet, and the longitudinal magnetic field $B_z(\\psi)$. The equations can be completely solved when $|v|=1$, and when $|v|jet that has vanishing electromagnetic pressure $\\tfrac{1}{2}(B^2-E^2)$ and requires no external pressure for confinement. We prove that such self-confinement is impossible when $B^2>E^2$. Finally, we write down specific solutions approximating numerical results for the nonaxisymmetric jet produced by a spinning black hole in an external, misaligned magnetic field.

  14. Wave turbulent statistics in non-weak wave turbulence

    E-Print Network [OSTI]

    Naoto Yokoyama

    2011-05-08

    In wave turbulence, it has been believed that statistical properties are well described by the weak turbulence theory, in which nonlinear interactions among wavenumbers are assumed to be small. In the weak turbulence theory, separation of linear and nonlinear time scales derived from the weak nonlinearity is also assumed. However, the separation of the time scales is often violated even in weak turbulent systems where the nonlinear interactions are actually weak. To get rid of this inconsistency, closed equations are derived without assuming the separation of the time scales in accordance with Direct-Interaction Approximation (DIA), which has been successfully applied to Navier--Stokes turbulence. The kinetic equation of the weak turbulence theory is recovered from the DIA equations if the weak nonlinearity is assumed as an additional assumption. It suggests that the DIA equations is a natural extension of the conventional kinetic equation to not-necessarily-weak wave turbulence.

  15. The National Ignition Facility and the Path to Fusion Energy

    SciTech Connect (OSTI)

    Moses, E

    2011-07-26

    The National Ignition Facility (NIF) is operational and conducting experiments at the Lawrence Livermore National Laboratory (LLNL). The NIF is the world's largest and most energetic laser experimental facility with 192 beams capable of delivering 1.8 megajoules of 500-terawatt ultraviolet laser energy, over 60 times more energy than any previous laser system. The NIF can create temperatures of more than 100 million degrees and pressures more than 100 billion times Earth's atmospheric pressure. These conditions, similar to those at the center of the sun, have never been created in the laboratory and will allow scientists to probe the physics of planetary interiors, supernovae, black holes, and other phenomena. The NIF's laser beams are designed to compress fusion targets to the conditions required for thermonuclear burn, liberating more energy than is required to initiate the fusion reactions. Experiments on the NIF are focusing on demonstrating fusion ignition and burn via inertial confinement fusion (ICF). The ignition program is conducted via the National Ignition Campaign (NIC) - a partnership among LLNL, Los Alamos National Laboratory, Sandia National Laboratories, University of Rochester Laboratory for Laser Energetics, and General Atomics. The NIC program has also established collaborations with the Atomic Weapons Establishment in the United Kingdom, Commissariat a Energie Atomique in France, Massachusetts Institute of Technology, Lawrence Berkeley National Laboratory, and many others. Ignition experiments have begun that form the basis of the overall NIF strategy for achieving ignition. Accomplishing this goal will demonstrate the feasibility of fusion as a source of limitless, clean energy for the future. This paper discusses the current status of the NIC, the experimental steps needed toward achieving ignition and the steps required to demonstrate and enable the delivery of fusion energy as a viable carbon-free energy source.

  16. Particle Physics Phenomenology 8. QCD jets and jet algorithms

    E-Print Network [OSTI]

    Sjöstrand, Torbjörn

    Particle Physics Phenomenology 8. QCD jets and jet algorithms Torbj¨orn Sj¨ostrand Department k. All rotationally symmetric. SppS (CERN): need to separate beam jets from highp ones. First solution: cone jets in (, ) space, e.g. UA1. (Second solution: clustering like Durham

  17. Modeling jet and outflow feedback during star cluster formation

    SciTech Connect (OSTI)

    Federrath, Christoph; Schrön, Martin; Banerjee, Robi; Klessen, Ralf S.

    2014-08-01

    Powerful jets and outflows are launched from the protostellar disks around newborn stars. These outflows carry enough mass and momentum to transform the structure of their parent molecular cloud and to potentially control star formation itself. Despite their importance, we have not been able to fully quantify the impact of jets and outflows during the formation of a star cluster. The main problem lies in limited computing power. We would have to resolve the magnetic jet-launching mechanism close to the protostar and at the same time follow the evolution of a parsec-size cloud for a million years. Current computer power and codes fall orders of magnitude short of achieving this. In order to overcome this problem, we implement a subgrid-scale (SGS) model for launching jets and outflows, which demonstrably converges and reproduces the mass, linear and angular momentum transfer, and the speed of real jets, with ?1000 times lower resolution than would be required without the SGS model. We apply the new SGS model to turbulent, magnetized star cluster formation and show that jets and outflows (1) eject about one-fourth of their parent molecular clump in high-speed jets, quickly reaching distances of more than a parsec, (2) reduce the star formation rate by about a factor of two, and (3) lead to the formation of ?1.5 times as many stars compared to the no-outflow case. Most importantly, we find that jets and outflows reduce the average star mass by a factor of ? three and may thus be essential for understanding the characteristic mass of the stellar initial mass function.

  18. Thermographic analysis of turbulent non-isothermal water boundary layer

    E-Print Network [OSTI]

    Znamenskaya, Irina A

    2015-01-01

    The paper is devoted to the investigation of the turbulent water boundary layer in the jet mixing flows using high-speed infrared (IR) thermography. Two turbulent mixing processes were studied: a submerged water jet impinging on a flat surface and two intersecting jets in a round disc-shaped vessel. An infrared camera (FLIR Systems SC7700) was focused on the window transparent for IR radiation; it provided high-speed recordings of heat fluxes from a thin water layer close to the window. Temperature versus time curves at different points of water boundary layer near the wall surface were acquired using the IR camera with the recording frequency of 100 Hz. The time of recording varied from 3 till 20 min. The power spectra for the temperature fluctuations at different points on the hot-cold water mixing zone were calculated using the Fast Fourier Transform algorithm. The obtained spectral behavior was compared to the Kolmogorov "-5/3 spectrum" (a direct energy cascade) and the dual-cascade scenario predicted for...

  19. Using indium tin oxide material to implement the imaging of microwave plasma ignition process

    SciTech Connect (OSTI)

    Wang, Qiang; Hou, Lingyun; Zhang, Guixin Zhang, Boya; Liu, Cheng; Wang, Zhi; Huang, Jian

    2014-02-17

    In this paper, a method is introduced to get global observation of microwave plasma ignition process at high pressure. A microwave resonator was designed with an indium tin oxide coated glass at bottom. Microwave plasma ignition was implemented in methane and air mixture at 10 bars by a 2?ms-3?kW-2.45?GHz microwave pulse, and the high speed images of the ignition process were obtained. The images visually proved that microwave plasma ignition could lead to a multi-point ignition. The system may also be applied to obtain Schlieren images, which is commonly used to observe the development of flame kernel in an ignition process.

  20. Characterization of Relativistic MHD Turbulence

    E-Print Network [OSTI]

    Garrison, David

    2015-01-01

    The objective of this work is to understand if and how the characteristics of relativistic MHD turbulence may differ from those of nonrelativistic MHD turbulence. We accomplish this by studying the invariants in the relativistic case and comparing them to what we know of nonrelativistic turbulence. Although much work has been done to understand the dynamics of nonrelativistic systems (mostly for ideal incompressible fluids), there is minimal literature explicitly describing the dynamics of relativistic MHD turbulence. Many authors simply assume that relativistic turbulence has the same invariants and obeys the same inverse energy cascade as non-relativistic systems.

  1. EPISODIC JETS AS THE CENTRAL ENGINE OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Yuan Feng [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang Bing, E-mail: fyuan@shao.ac.cn, E-mail: zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)

    2012-09-20

    Most gamma-ray bursts (GRBs) have erratic light curves, which demand that the GRB central engine launches an episodic outflow. Recent Fermi observations of some GRBs indicate a lack of the thermal photosphere component as predicted by the baryonic fireball model, which suggests a magnetic origin of GRBs. Given that powerful episodic jets have been observed along with continuous jets in other astrophysical black hole systems, here we propose an intrinsically episodic, magnetically dominated jet model for the GRB central engine. Accumulation and eruption of free magnetic energy in the corona of a differentially rotating, turbulent accretion flow around a hyperaccreting black hole lead to ejections of episodic, magnetically dominated plasma blobs. These blobs are accelerated magnetically, collide with each other at large radii, trigger rapid magnetic reconnection and turbulence, efficient particle acceleration, and radiation, and power the observed episodic prompt gamma-ray emission from GRBs.

  2. Static magnetic fields enhance turbulence

    E-Print Network [OSTI]

    Pothérat, Alban

    2015-01-01

    More often than not, turbulence occurs under the influence of external fields, mostly rotation and magnetic fields generated either by planets, stellar objects or by an industrial environment. Their effect on the anisotropy and the dissipative behaviour of turbulence is recognised but complex, and it is still difficult to even tell whether they enhance or dampen turbulence. For example, externally imposed magnetic fields suppress free turbulence in electrically conducting fluids (Moffatt 1967), and make it two-dimensional (2D) (Sommeria & Moreau 1982); but their effect on the intensity of forced turbulence, as in pipes, convective flows or otherwise, is not clear. We shall prove that since two-dimensionalisation preferentially affects larger scales, these undergo much less dissipation and sustain intense turbulent fluctuations. When higher magnetic fields are imposed, quasi-2D structures retain more kinetic energy, so that rather than suppressing forced turbulence, external magnetic fields indirectly enha...

  3. National Ignition Facility Configuration Management Plan

    SciTech Connect (OSTI)

    Cabral, S G; Moore, T L

    2002-10-01

    This Configuration Management Plan (CMP) describes the technical and administrative management process for controlling the National Ignition Facility (NIF) Project configuration. The complexity of the NIF Project (i.e., participation by multiple national laboratories and subcontractors involved in the development, fabrication, installation, and testing of NIF hardware and software, as well as construction and testing of Project facilities) requires implementation of the comprehensive configuration management program defined in this plan. A logical schematic illustrating how the plan functions is provided in Figure 1. A summary of the process is provided in Section 4.0, Configuration Change Control. Detailed procedures that make up the overall process are referenced. This CMP is consistent with guidance for managing a project's configuration provided in Department of Energy (DOE) Order 430.1, Guide PMG 10, ''Project Execution and Engineering Management Planning''. Configuration management is a formal discipline comprised of the following four elements: (1) Identification--defines the functional and physical characteristics of a Project and uniquely identifies the defining requirements. This includes selection of components of the end product(s) subject to control and selection of the documents that define the project and components. (2) Change management--provides a systematic method for managing changes to the project and its physical and functional configuration to ensure that all changes are properly identified, assessed, reviewed, approved, implemented, tested, and documented. (3) Data management--ensures that necessary information on the project and its end product(s) is systematically recorded and disseminated for decision-making and other uses. Identifies, stores and controls, tracks status, retrieves, and distributes documents. (4) Assessments and validation--ensures that the planned configuration requirements match actual physical configurations and approved changes are implemented according to the change requirements documents.

  4. SHOCK CORRUGATION BY RAYLEIGH-TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS

    SciTech Connect (OSTI)

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2014-08-10

    Afterglow jets are Rayleigh-Taylor unstable and therefore turbulent during the early part of their deceleration. There are also several processes which actively cool the jet. In this Letter, we demonstrate that if cooling significantly increases the compressibility of the flow, the turbulence collides with the forward shock, destabilizing and corrugating it. In this case, the forward shock is turbulent enough to produce the magnetic fields responsible for synchrotron emission via small-scale turbulent dynamo. We calculate light curves assuming the magnetic field is in energy equipartition with the turbulent kinetic energy and discover that dynamic magnetic fields are well approximated by a constant magnetic-to-thermal energy ratio of 1%, though there is a sizeable delay in the time of peak flux as the magnetic field turns on only after the turbulence has activated. The reverse shock is found to be significantly more magnetized than the forward shock, with a magnetic-to-thermal energy ratio of the order of 10%. This work motivates future Rayleigh-Taylor calculations using more physical cooling models.

  5. Methane ignition catalyzed by in situ generated palladium nanoparticles

    SciTech Connect (OSTI)

    Shimizu, T.; Abid, A.D.; Poskrebyshev, G.; Wang, H. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089 (United States); Nabity, J.; Engel, J.; Yu, J. [TDA Research, Inc., 12345 W. 52nd Ave, Wheat Ridge, CO 80033 (United States); Wickham, D. [Reaction Systems, LLC, 19039 E. Plaza Drive, Suite 290, Parker, CO 80134 (United States); Van Devener, B.; Anderson, S.L. [Department of Chemistry, University of Utah, Salt Lake City, UT 84112 (United States); Williams, S. [Air Force Research Laboratory, Mail Stop RZA, 1950 Fifth Street, WPAFB, OH 45433 (United States)

    2010-03-15

    Catalytic ignition of methane over the surfaces of freely-suspended and in situ generated palladium nanoparticles was investigated experimentally and numerically. The experiments were conducted in a laminar flow reactor. The palladium precursor was a compound (Pd(THD){sub 2}, THD: 2,2,6,6-tetramethyl-3,5-heptanedione) dissolved in toluene and injected into the flow reactor as a fine aerosol, along with a methane-oxygen-nitrogen mixture. For experimental conditions chosen in this study, non-catalytic, homogeneous ignition was observed at a furnace temperature of {proportional_to}1123 K, whereas ignition of the same mixture with the precursor was found to be {proportional_to}973 K. In situ production of Pd/PdO nanoparticles was confirmed by scanning mobility, transmission electron microscopy and X-ray photoelectron spectroscopy analyses of particles collected at the reactor exit. The catalyst particle size distribution was log-normal. Depending on the precursor loading, the median diameter ranged from 10 to 30 nm. The mechanism behind catalytic ignition was examined using a combined gas-phase and gas-surface reaction model. Simulation results match the experiments closely and suggest that palladium nanocatalyst significantly shortens the ignition delay times of methane-air mixtures over a wide range of conditions. (author)

  6. Angular Scaling In Jets

    SciTech Connect (OSTI)

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC

    2012-02-17

    We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.

  7. Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels

    SciTech Connect (OSTI)

    Peterson, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankat; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Camou, Alejandro; Aul, Christopher

    2013-09-30

    This final report documents the technical results of the 3-year project entitled, “Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels,” funded under the NETL of DOE. The research was conducted under six main tasks: 1) program management and planning; 2) turbulent flame speed measurements of syngas mixtures; 3) laminar flame speed measurements with diluents; 4) NOx mechanism validation experiments; 5) fundamental NOx kinetics; and 6) the effect of impurities on NOx kinetics. Experiments were performed using primary constant-volume vessels for laminar and turbulent flame speeds and shock tubes for ignition delay times and species concentrations. In addition to the existing shock- tube and flame speed facilities, a new capability in measuring turbulent flame speeds was developed under this grant. Other highlights include an improved NOx kinetics mechanism; a database on syngas blends for real fuel mixtures with and without impurities; an improved hydrogen sulfide mechanism; an improved ammonia kintics mechanism; laminar flame speed data at high pressures with water addition; and the development of an inexpensive absorption spectroscopy diagnostic for shock-tube measurements of OH time histories. The Project Results for this work can be divided into 13 major sections, which form the basis of this report. These 13 topics are divided into the five areas: 1) laminar flame speeds; 2) Nitrogen Oxide and Ammonia chemical kinetics; 3) syngas impurities chemical kinetics; 4) turbulent flame speeds; and 5) OH absorption measurements for chemical kinetics.

  8. Maximizing Power Output in Homogeneous Charge Compression Ignition (HCCI) Engines and Enabling Effective Control of Combustion Timing

    E-Print Network [OSTI]

    Saxena, Samveg

    2011-01-01

    4 Stratified charge compression ignition -ratios [9]. 2.2.2 Stratified charge compression ignition -to create areas of stratified charge. The effectiveness of

  9. Data Analysis, Pre-Ignition Assessment, and Post-Ignition Modeling of the Large-Scale Annular Cookoff Tests

    SciTech Connect (OSTI)

    G. Terrones; F.J. Souto; R.F. Shea; M.W.Burkett; E.S. Idar

    2005-09-30

    In order to understand the implications that cookoff of plastic-bonded explosive-9501 could have on safety assessments, we analyzed the available data from the large-scale annular cookoff (LSAC) assembly series of experiments. In addition, we examined recent data regarding hypotheses about pre-ignition that may be relevant to post-ignition behavior. Based on the post-ignition data from Shot 6, which had the most complete set of data, we developed an approximate equation of state (EOS) for the gaseous products of deflagration. Implementation of this EOS into the multimaterial hydrodynamics computer program PAGOSA yielded good agreement with the inner-liner collapse sequence for Shot 6 and with other data, such as velocity interferometer system for any reflector and resistance wires. A metric to establish the degree of symmetry based on the concept of time of arrival to pin locations was used to compare numerical simulations with experimental data. Several simulations were performed to elucidate the mode of ignition in the LSAC and to determine the possible compression levels that the metal assembly could have been subjected to during post-ignition.

  10. Volume Ignition via Time-like Detonation in Pellet Fusion

    E-Print Network [OSTI]

    Csernai, L P

    2015-01-01

    Relativistic fluid dynamics and the theory of relativistic detonation fronts are used to estimate the space-time dynamics of the burning of the D-T fuel in Laser driven pellet fusion experiments. The initial "High foot" heating of the fuel makes the compressed target transparent to radiation, and then a rapid ignition pulse can penetrate and heat up the whole target to supercritical temperatures in a short time, so that most of the interior of the target ignites almost simultaneously and instabilities will have no time to develop. In these relativistic, radiation dominated processes both the interior, time-like burning front and the surrounding space-like part of the front will be stable against Rayleigh-Taylor instabilities. To achieve this rapid, volume ignition the pulse heating up the target to supercritical temperature should provide the required energy in less than ~ 10 ps.

  11. Stratified-charge glow plug ignition engine experiments. Topical report

    SciTech Connect (OSTI)

    Thring, R.H.; Leet, J.A.

    1991-05-01

    An investigation was conducted to study the feasibility of operating a natural gas two-stroke engine using glow plug ignition with very lean mixtures. The term Stratified-Charge Glow Plus Ignition (SCGI) was coined to describe the engine. A JLO DL 365 single-cylinder, two-stroke, diesel engine was converted first to a natural gas fueled spark-ignited engine for the baseline tests, and then to the SCGI engine. The engine was successfully run, but was found to be sensitive to various conditions such as the glow plug temperature. The engine ran very lean, to an equivalence ratio of 0.33, offering the potential of good fuel economy and low NOx emissions. Numerous photographs, diagrams, and charts are included.

  12. Ion beam requirements for fast ignition of inertial fusion targets

    E-Print Network [OSTI]

    Honrubia, J J

    2015-01-01

    Ion beam requirements for fast ignition are investigated by numerical simulation taking into account new effects such as ion beam divergence not included before. We assume that ions are generated by the TNSA scheme in a curved foil placed inside a re-entrant cone and focused on the cone apex or beyond. From the focusing point to the compressed core ions propagate with a given divergence angle. Ignition energies are obtained for two compressed fuel configurations heated by proton and carbon ion beams. The dependence of the ignition energies on the beam divergence angle and on the position of the ion beam focusing point have been analysed. Comparison between TNSA and quasi-monoenergetic ions is also shown.

  13. Development of nuclear diagnostics for the National Ignition Facility (invited)

    SciTech Connect (OSTI)

    Glebov, V. Yu.; Meyerhofer, D. D.; Sangster, T. C.; Stoeckl, C.; Roberts, S.; Barrera, C. A.; Celeste, J. R.; Cerjan, C. J.; Dauffy, L. S.; Eder, D. C.; Griffith, R. L.; Haan, S. W.; Hammel, B. A.; Hatchett, S. P.; Izumi, N.; Kimbrough, J. R.; Koch, J. A.; Landen, O. L.; Lerche, R. A.; MacGowan, B. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); CEA-DAM, lle de France, BP 12, 91680 Bruyeres-le-Chatel (France); Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); SUNY Geneseo, Geneseo, New York 14454 (United States); Atomic Weapons Establishment (AWE), Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); National Security Technologies, Nevada, North Las Vegas, Nevada 89030 (United States)] (and others)

    2006-10-15

    The National Ignition Facility (NIF) will provide up to 1.8 MJ of laser energy for imploding inertial confinement fusion (ICF) targets. Ignited NIF targets are expected to produce up to 10{sup 19} DT neutrons. This will provide unprecedented opportunities and challenges for the use of nuclear diagnostics in ICF experiments. In 2005, the suite of nuclear-ignition diagnostics for the NIF was defined and they are under development through collaborative efforts at several institutions. This suite includes PROTEX and copper activation for primary yield measurements, a magnetic recoil spectrometer and carbon activation for fuel areal density, neutron time-of-flight detectors for yield and ion temperature, a gamma bang time detector, and neutron imaging systems for primary and downscattered neutrons. An overview of the conceptual design, the developmental status, and recent results of prototype tests on the OMEGA laser will be presented.

  14. Nonaxisymmetric Poynting Jets

    E-Print Network [OSTI]

    Gralla, Samuel E

    2015-01-01

    The relativistic plasma jets from a misaligned black hole-accretion disk system will not be axially symmetric. Here we analyze nonaxisymmetric, stationary, translation invariant jets in the force-free approximation where the field energy dominates the particle energy. We derive a stream equation for these configurations involving the flux function $\\psi$ for the transverse magnetic field, the linear velocity $v(\\psi)$ of field lines along the jet, and the longitudinal magnetic field $B_z(\\psi)$. The equations can be completely solved when $|v|=1$, and when $|v|E^2$. Finally, we write down specific solutions approximating numerical results for the nonaxisymmetric jet produced by a spinning black hole in an external, misaligned magnetic field.

  15. Plasma channel from EP beam Direct-drive ignition is the main thrust in LLE

    E-Print Network [OSTI]

    -drive ignition; this is not an optimal configuration fordirectdrivethatrequiressphericalillumination I2093 26 kJ Scale 1:70 in energy Scale 1:1 Scale 1:1 #12;Hydro-equivalentignitiononOMEGA #12;Ignition

  16. The National Ignition Facility: A New Era in High Energy Density Science

    SciTech Connect (OSTI)

    Moses, E

    2009-06-10

    The National Ignition Facility, the world's most energetic laser system, is now operational. This talk will describe NIF, the ignition campaign, and new opportunities in fusion energy and high energy density science enabled by NIF.

  17. GROWTH OF A LOCALIZED SEED MAGNETIC FIELD IN A TURBULENT MEDIUM

    SciTech Connect (OSTI)

    Cho, Jungyeon; Yoo, Hyunju

    2012-11-10

    Turbulence dynamo deals with the amplification of a seed magnetic field in a turbulent medium and has been studied mostly for uniform or spatially homogeneous seed magnetic fields. However, some astrophysical processes (e.g., jets from active galaxies, galactic winds, or ram-pressure stripping in galaxy clusters) can provide localized seed magnetic fields. In this paper, we numerically study amplification of localized seed magnetic fields in a turbulent medium. Throughout the paper, we assume that the driving scale of turbulence is comparable to the size of the system. Our findings are as follows. First, turbulence can amplify a localized seed magnetic field very efficiently. The growth rate of magnetic energy density is as high as that for a uniform seed magnetic field. This result implies that magnetic field ejected from an astrophysical object can be a viable source of a magnetic field in a cluster. Second, the localized seed magnetic field disperses and fills the whole system very fast. If turbulence in a system (e.g., a galaxy cluster or a filament) is driven at large scales, we expect that it takes a few large-eddy turnover times for the magnetic field to fill the whole system. Third, growth and turbulence diffusion of a localized seed magnetic field are also fast in high magnetic Prandtl number turbulence. Fourth, even in decaying turbulence, a localized seed magnetic field can ultimately fill the whole system. Although the dispersal rate of the magnetic field is not fast in purely decaying turbulence, it can be enhanced by an additional forcing.

  18. A TUTORIAL ON IGNITION AND GAIN FOR SMALL FUSION TARGETS

    SciTech Connect (OSTI)

    Kirkpatrick, R. C. [Los Alamos National Laboratory, Los Alamos, NM 087545 (United States)

    2009-07-26

    Nuclear fusion was discovered experimentally in 1933-34 and other charged particle nuclear reactions were documented shortly thereafter. Work in earnest on the fusion ignition problem began with Edward Teller's group at Los Alamos during the war years. His group quantified all the important basic atomic and nuclear processes and summarized their interactions. A few years later, the success of the early theory developed at Los Alamos led to very successful thermonuclear weapons, but also to decades of unsuccessful attempts to harness fusion as an energy source of the future. The reasons for this history are many, but it seems appropriate to review some of the basics with the objective of identifying what is essential for success and what is not. This tutorial discusses only the conditions required for ignition in small fusion targets and how the target design impacts driver requirements. Generally speaking, the driver must meet the energy, power and power density requirements needed by the fusion target. The most relevant parameters for ignition of the fusion fuel are the minimum temperature and areal density (rhoR), but these parameters set secondary conditions that must be achieved, namely an implosion velocity, target size and pressure, which are interrelated. Despite the apparent simplicity of inertial fusion targets, there is not a single mode of fusion ignition, and the necessary combination of minimum temperature and areal density depends on the mode of ignition. However, by providing a magnetic field of sufficient strength, the conditions needed for fusion ignition can be drastically altered. Magnetized target fusion potentially opens up a vast parameter space between the extremes of magnetic and inertial fusion.

  19. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zylstra, A. B.; Frenje, J. A.; Seguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Friedrich, S.; Bionta, R.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Berzak Hopkins, L.; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dixit, S.; Doppner, T.; Edgell, D.; Edwards, M. J.; Gatu Johnson, M.; Glenn, S.; Glenzer, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Macphee, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moody, J.; Moses, E.; Nagel, S.R.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Rosen, M.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Springer, P.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Zacharias, R.

    2014-11-01

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2! higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.

  20. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    SciTech Connect (OSTI)

    Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2014-11-15

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D{sup 3}He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D{sup 3}He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (?R) and the shell center-of-mass radius (R{sub cm}) from the downshift of the shock-produced D{sup 3}He protons. The observed ?R at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time (“short-coast”), while longer-coasting implosions have lower ?R. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (?800 ps) than in the short-coast (?400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel ?R.

  1. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    SciTech Connect (OSTI)

    Zylstra, A. B. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Frenje, J. A. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Seguin, F. H. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Hicks, D. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dewald, E. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Robey, H. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rygg, J. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Meezan, N. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rosenberg, M. J. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Rinderknecht, H. G. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Friedrich, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bionta, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Olson, R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Los Alamos National Lab., NM (United States); Atherton, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barrios, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bell, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Benedetti, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Berzak Hopkins, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Betti, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Bradley, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Callahan, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Casey, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Collins, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dixit, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Doppner, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Edgell, D. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Edwards, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gatu Johnson, M. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Glenn, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glenzer, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Grim, G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hatchett, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jones, O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Khan, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kilkenny, J. [General Atomics, San Diego, CA (United States); Kline, J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Knauer, J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Kritcher, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kyrala, G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Landen, O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); LePape, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Li, C. K. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Lindl, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ma, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mackinnon, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Macphee, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-11-01

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2! higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.

  2. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; et al

    2014-11-03

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infermore »the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.« less

  3. Correlating cookoff violence with pre-ignition damage.

    SciTech Connect (OSTI)

    Wente, William Baker; Hobbs, Michael L.; Kaneshige, Michael Jiro

    2010-03-01

    Predicting the response of energetic materials during accidents, such as fire, is important for high consequence safety analysis. We hypothesize that responses of ener-getic materials before and after ignition depend on factors that cause thermal and chemi-cal damage. We have previously correlated violence from PETN to the extent of decom-position at ignition, determined as the time when the maximum Damkoehler number ex-ceeds a threshold value. We seek to understand if our method of violence correlation ap-plies universally to other explosive starting with RDX.

  4. Exhaust gas recirculation in a homogeneous charge compression ignition engine

    DOE Patents [OSTI]

    Duffy, Kevin P. (Metamora, IL); Kieser, Andrew J. (Morton, IL); Rodman, Anthony (Chillicothe, IL); Liechty, Michael P. (Chillicothe, IL); Hergart, Carl-Anders (Peoria, IL); Hardy, William L. (Peoria, IL)

    2008-05-27

    A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

  5. Ignition feedback regenerative free electron laser (FEL) amplifier

    DOE Patents [OSTI]

    Kim, Kwang-Je (Burr Ridge, IL); Zholents, Alexander (Walnut Creek, CA); Zolotorev, Max (Oakland, CA)

    2001-01-01

    An ignition feedback regenerative amplifier consists of an injector, a linear accelerator with energy recovery, and a high-gain free electron laser amplifier. A fraction of the free electron laser output is coupled to the input to operate the free electron laser in the regenerative mode. A mode filter in this loop prevents run away instability. Another fraction of the output, after suitable frequency up conversion, is used to drive the photocathode. An external laser is provided to start up both the amplifier and the injector, thus igniting the system.

  6. Polymer Stretching by Turbulence

    SciTech Connect (OSTI)

    Chertkov, Michael

    2000-05-15

    The stretching of a polymer chain by a large-scale chaotic flow is considered. The steady state which emerges as a balance of the turbulent stretching and anharmonic resistance of the chain is quantitatively described, i.e., the dependency on the flow parameters (Lyapunov exponent statistics) and the chain characteristics (the number of beads and the interbead elastic potential) is made explicit. (c) 2000 The American Physical Society.

  7. CX-010179: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Modeling and Experimental Studies of Controllable Cavity Turbulent Jet Ignition CX(s) Applied: B3.6 Date: 04/25/2013 Location(s): Michigan Offices(s): National Energy Technology Laboratory

  8. Few-Freedom Turbulence

    E-Print Network [OSTI]

    B. V. Chirikov; V. G. Davidovsky

    2000-06-15

    The results of numerical experiments on the structure of chaotic attractors in the Khalatnikov - Kroyter model of two freedoms are presented. This model was developed for a qualitative description of the wave turbulence of the second sound in helium. The attractor dimension, size, and the maximal Lyapunov exponent in dependence on the single dimensionless parameter $F$ of the model are found and discussed. The principal parameter $F$ is similar to the Reynolds number in hydrodynamic turbulence. We were able to discern four different attractors characterized by a specific critical value of the parameter ($F=F_{cr}$), such that the attractor exists for $F>F_{cr}$ only. A simple empirical relation for this dependence on the argument ($F-F_{cr}$) is presented which turns out to be universal for different attractors with respect to the dimension and dimensionless Lyapunov exponents. Yet, it differs as to the size of attractor. In the main region of our studies the dependence of all dimensionless characteristics of the chaotic attractor on parameter $F$ is very slow (logarithmic) which is qualitatively different as compared to that of a multi-freedom attractor, e.g., in hydrodynamic turbulence (a power law). However, at very large $F\\sim 10^7$ the transition to a power-law dependence has been finally found, similar to the multi-freedom attractor. Some unsolved problems and open questions are also discussed.

  9. Prediction of turbulent flow and local heat transfer in internally cooled turbine airfoils: the leading edge region 

    E-Print Network [OSTI]

    Pontaza, Juan Pablo

    2013-02-22

    -Stokes equations and the energy equation in conjunction with a two-layer K-Epsilon isotropic eddy viscosity model and a near-wall Reynolds-Stress closure model. The fundamental cases of fully developed turbulent pipe flow and an axisymmetric jet impinging on a...

  10. Chaotic self-sustaining structure embeded in turbulent-laminar interface

    E-Print Network [OSTI]

    Teramura, Toshiki

    2015-01-01

    An iterface structure between turbulence and laminar flow is investigated in two-dimensional channel flow. This spatially localized structure not only sustains itself, but also converts laminar state into turbulence actively. In other words, this coherent structure has a functionality to generate inhomogeneity by its inner dynamics. The dynamics of this functional coherent structure is isolated using the filtered simulation, and a physical perspective of its dynamics is summarized in a phenomenological model called an "ejection-jet" cycle, which includes multiscale interaction process.

  11. Chaotic self-sustaining structure embeded in turbulent-laminar interface

    E-Print Network [OSTI]

    Toshiki Teramura; Sadayoshi Toh

    2015-03-16

    An iterface structure between turbulence and laminar flow is investigated in two-dimensional channel flow. This spatially localized structure not only sustains itself, but also converts laminar state into turbulence actively. In other words, this coherent structure has a functionality to generate inhomogeneity by its inner dynamics. The dynamics of this functional coherent structure is isolated using the filtered simulation, and a physical perspective of its dynamics is summarized in a phenomenological model called an "ejection-jet" cycle, which includes multiscale interaction process.

  12. Simulating flame lift-off characteristics of diesel and biodiesel fuels using detailed chemical-kinetic mechanisms and LES turbulence model.

    SciTech Connect (OSTI)

    Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E (Energy Systems); (Univ. of Connecticut); (CONVERGENT Science)

    2012-01-01

    Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the lifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray development processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesel and biodiesel fuels, as well as Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame lift-off lengths (LOLs) and ignition delays. Specifically, two chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the RNG k-{epsilon} (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resolution, minimum grid sizes of 250 {micro}m and 125 {micro}m were obtained for the RANS and LES cases respectively. Validations of these models were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition delay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-{epsilon} model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl 9-decenoate, and NHPT, results in better predicted LOLs and ignition delays. For diesel fuel though, only marginal improvements are observed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.

  13. Eddy fluxes in baroclinic turbulence

    E-Print Network [OSTI]

    Thompson, Andrew F.

    2006-01-01

    cant dissipation of tidal energy in the deep ocean inferred2006: An estimate of tidal energy lost to turbulence at the

  14. Sandia Energy - Applied Turbulent Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and they form the basis for the creation of validated submodels that bridge fundamental energy sciences with applied device engineering and optimization. Turbulent-combustion-lab...

  15. ENGINEERING FEATURES OF THE FUSION IGNITION RESEARCH EXPERIMENT (FIRE)

    E-Print Network [OSTI]

    ENGINEERING FEATURES OF THE FUSION IGNITION RESEARCH EXPERIMENT (FIRE) R.J. Thomea and P.J. Heitzenroederb for the FIRE Design Team a MIT Plasma Science and Fusion Center, 185 Albany St, Cambridge, MA, USA Box 451, Princeton, NJ, USA 08543 The FIRE tokamak is an option for the next step in the US magnetic

  16. ENGINEERING STATUS OF THE FUSION IGNITION RESEARCH EXPERIMENT (FIRE)

    E-Print Network [OSTI]

    ENGINEERING STATUS OF THE FUSION IGNITION RESEARCH EXPERIMENT (FIRE) Philip J. Heitzenroeder Dale 08543 Cambridge, MA 02139 (609)-243-3043 (609)-243-3301 (617)-253-8155 For the FIRE Project Team ABSTRACT FIRE is a compact, high field tokamak being studied as an option for the next step in the US

  17. Carbon dioxide emission during forest fires ignited by lightning

    E-Print Network [OSTI]

    Pelc, Magdalena

    2009-01-01

    In this paper we developed the model for the carbon dioxide emission from forest fire. The master equation for the spreading of the carbon dioxide to atmosphere is the hyperbolic diffusion equation. In the paper we study forest fire ignited by lightning. In that case the fores fire has the well defined front which propagates with finite velocity.

  18. Carbon dioxide emission during forest fires ignited by lightning

    E-Print Network [OSTI]

    Magdalena Pelc; Radoslaw Osuch

    2009-03-31

    In this paper we developed the model for the carbon dioxide emission from forest fire. The master equation for the spreading of the carbon dioxide to atmosphere is the hyperbolic diffusion equation. In the paper we study forest fire ignited by lightning. In that case the fores fire has the well defined front which propagates with finite velocity.

  19. On Operational Power Reactor Regime and Ignited Spherical Tokamaks

    E-Print Network [OSTI]

    Zakharov, Leonid E.

    , 2003 version of the "cold" magnetic "Fusion without ignition" in the next 35 years, the talk.-Pitersburg, St.-Pitersburg, RF % Insutute of Nuclear Fusion, RRC "Kurchatov Ins.", Moscow, RF & Vyoptics, Inc for magnetic fusion, OPRR requires a low recycling and wall-stabilized high- plasma. Because of the small

  20. Optimization of the process of plasma ignition of coal

    SciTech Connect (OSTI)

    Peregudov, V.S.

    2009-04-15

    Results are given of experimental and theoretical investigations of plasma ignition of coal as a result of its thermochemical preparation in application to the processes of firing up a boiler and stabilizing the flame combustion. The experimental test bed with a commercial-scale burner is used for determining the conditions of plasma ignition of low-reactivity high-ash anthracite depending on the concentration of coal in the air mixture and velocity of the latter. The calculations produce an equation (important from the standpoint of practical applications) for determining the energy expenditure for plasma ignition of coal depending on the basic process parameters. The tests reveal the difficulties arising in firing up a boiler with direct delivery of pulverized coal from the mill to furnace. A scheme is suggested, which enables one to reduce the energy expenditure for ignition of coal and improve the reliability of the process of firing up such a boiler. Results are given of calculation of plasma thermochemical preparation of coal under conditions of lower concentration of oxygen in the air mixture.

  1. Homogeneous Charge Compression Ignition: Formulation Effect of a Diesel Fuel

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Homogeneous Charge Compression Ignition: Formulation Effect of a Diesel Fuel on the Initiation and the Combustion Potential of Olefin Impact in a Diesel Base Fuel D. Alseda1,2, X. Montagne1 and P. Dagaut2 1 -- Combustion en mode HCCI : impact de la formulation d'un carburant Diesel sur l'initiation et la combustion

  2. Safety analysis of optically ignited explosive and pyrotechnic devices

    SciTech Connect (OSTI)

    Merson, J.A.; Salas, F.J.; Holswade, S.

    1994-05-01

    The future of optical ordnance depends on the acceptance, validation and verification of the stated safety enhancement claims of optical ordnance over existing electrical explosive devices (EED`s). Sandia has been pursuing the development of optical ordnance, with the primary motivation of this effort being the enhancement of explosive safety by specifically reducing the potential of premature detonation that can occur with low energy electrically ignited explosive devices. By using semiconductor laser diodes for igniting these devices, safety improvements can be made without being detrimental to current system concerns since the inputs required for these devices are similar to electrical systems. Laser Diode Ignition (LDI) of the energetic material provides the opportunity to remove the bridgewire and electrically conductive pins from the charge cavity, creating a Faraday cage and thus isolating the explosive or pyrotechnic materials from stray electrical ignition sources. Recent results from our continued study of safety enhancements are presented. The areas of investigation which are presented include: (1) unintended optical source analysis, specifically lightning insensitivity, (2) electromagnetic radiation (EMR) and electrostatic discharge (ESD) insensitivity analysis, and (3) powder safety.

  3. The first calculation of fractional jets

    E-Print Network [OSTI]

    Bertolini, Daniele

    In collider physics, jet algorithms are a ubiquitous tool for clustering particles into discrete jet objects. Event shapes offer an alternative way to characterize jets, and one can define a jet multiplicity event shape, ...

  4. Jet propulsion without inertia

    E-Print Network [OSTI]

    Saverio E. Spagnolie; Eric Lauga

    2010-05-04

    A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies, and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented, and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e. jetting) surfaces are considered, and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate, and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria.

  5. Evidence for internal structures of spiral turbulence

    E-Print Network [OSTI]

    2009-12-21

    Dec 22, 2009 ... ary laminar-turbulent pattern in plane Couette flow. ... flow internal to the turbulent and laminar spirals, and unique ... 2 ( is the fluid density).

  6. Supercomputers Capture Turbulence in the Solar Wind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Capture Turbulence in the Solar Wind Supercomputers Capture Turbulence in the Solar Wind Berkeley Lab visualizations could help scientists forecast destructive space weather...

  7. Simulation of lean premixed turbulent combustion

    E-Print Network [OSTI]

    2008-01-01

    turbulent methane combustion. Proc. Combust. Inst. , 29:in premixed turbulent combustion. Proc. Combust. Inst. ,for zero Mach number combustion. Combust. Sci. Technol. ,

  8. Mode 1 drive asymmetry in inertial confinement fusion implosions on the National Ignition Facility

    SciTech Connect (OSTI)

    Spears, Brian K. Edwards, M. J.; Hatchett, S.; Kritcher, A.; Lindl, J.; Munro, D.; Patel, P.; Robey, H. F.; Town, R. P. J.; Kilkenny, J.; Knauer, J.

    2014-04-15

    Mode 1 radiation drive asymmetry (pole-to-pole imbalance) at significant levels can have a large impact on inertial confinement fusion implosions at the National Ignition Facility (NIF). This asymmetry distorts the cold confining shell and drives a high-speed jet through the hot spot. The perturbed hot spot shows increased residual kinetic energy and reduced internal energy, and it achieves reduced pressure and neutron yield. The altered implosion physics manifests itself in observable diagnostic signatures, especially the neutron spectrum which can be used to measure the neutron-weighted flow velocity, apparent ion temperature, and neutron downscattering. Numerical simulations of implosions with mode 1 asymmetry show that the resultant simulated diagnostic signatures are moved toward the values observed in many NIF experiments. The diagnostic output can also be used to build a set of integrated implosion performance metrics. The metrics indicate that P{sub 1} has a significant impact on implosion performance and must be carefully controlled in NIF implosions.

  9. Gudrun's (NLO) list pp->WW jet

    E-Print Network [OSTI]

    Huston, Joey

    Gudrun's (NLO) list 2->3 pp->WW jet pp->VVV pp->H + 2 jets 2->4 pp->4 jets pp->tT + 2jets p->tT bB pp->V+ 3 jets pp->VV + 2 jets pp->VVV + jet pp->WW bB From technology point-of-view start with massless cases such as + 2 jets then add progressively more difficult calculations (additional scales

  10. Simulation of hydrogen and hydrogen-assisted propane ignition in Pt catalyzed microchannel

    SciTech Connect (OSTI)

    Seshadri, Vikram; Kaisare, Niket S.

    2010-11-15

    This paper deals with self-ignition of catalytic microburners from ambient cold-start conditions. First, reaction kinetics for hydrogen combustion is validated with experimental results from the literature, followed by validation of a simplified pseudo-2D microburner model. The model is then used to study the self-ignition behavior of lean hydrogen/air mixtures in a Platinum-catalyzed microburner. Hydrogen combustion on Pt is a very fast reaction. During cold start ignition, hydrogen conversion reaches 100% within the first few seconds and the reactor dynamics are governed by the ''thermal inertia'' of the microburner wall structure. The self-ignition property of hydrogen can be used to provide the energy required for propane ignition. Two different modes of hydrogen-assisted propane ignition are considered: co-feed mode, where the microburner inlet consists of premixed hydrogen/propane/air mixtures; and sequential feed mode, where the inlet feed is switched from hydrogen/air to propane/air mixtures after the microburner reaches propane ignition temperature. We show that hydrogen-assisted ignition is equivalent to selectively preheating the inlet section of the microburner. The time to reach steady state is lower at higher equivalence ratio, lower wall thermal conductivity, and higher inlet velocity for both the ignition modes. The ignition times and propane emissions are compared. Although the sequential feed mode requires slightly higher amount of hydrogen, the propane emissions are at least an order of magnitude lower than the other ignition modes. (author)

  11. Jets in Particle Colliders Andrew Wong!

    E-Print Network [OSTI]

    Budker, Dmitry

    Jets in Particle Colliders Andrew Wong! #12;Topics · What are jets? · How are they produced? · What do we use to study jets? #12;What are jets? · Bunch of different jets #12;Pretty picture! #12;What's in a jet? · Hadrons ­ Kaons, Pions, Protons, Neutrons · Leptons ­ Mainly electrons and muons · These have

  12. Organic vapor jet printing system

    DOE Patents [OSTI]

    Forrest, Stephen R

    2012-10-23

    An organic vapor jet printing system includes a pump for increasing the pressure of an organic flux.

  13. Jet Fuel from Microalgal Lipids

    SciTech Connect (OSTI)

    Not Available

    2006-07-01

    A fact sheet on production of jet fuel or multi-purpose military fuel from lipids produced by microalgae.

  14. Advances in compressible turbulent mixing

    SciTech Connect (OSTI)

    Dannevik, W.P.; Buckingham, A.C.; Leith, C.E.

    1992-01-01

    This volume includes some recent additions to original material prepared for the Princeton International Workshop on the Physics of Compressible Turbulent Mixing, held in 1988. Workshop participants were asked to emphasize the physics of the compressible mixing process rather than measurement techniques or computational methods. Actual experimental results and their meaning were given precedence over discussions of new diagnostic developments. Theoretical interpretations and understanding were stressed rather than the exposition of new analytical model developments or advances in numerical procedures. By design, compressibility influences on turbulent mixing were discussed--almost exclusively--from the perspective of supersonic flow field studies. The papers are arranged in three topical categories: Foundations, Vortical Domination, and Strongly Coupled Compressibility. The Foundations category is a collection of seminal studies that connect current study in compressible turbulent mixing with compressible, high-speed turbulent flow research that almost vanished about two decades ago. A number of contributions are included on flow instability initiation, evolution, and transition between the states of unstable flow onset through those descriptive of fully developed turbulence. The Vortical Domination category includes theoretical and experimental studies of coherent structures, vortex pairing, vortex-dynamics-influenced pressure focusing. In the Strongly Coupled Compressibility category the organizers included the high-speed turbulent flow investigations in which the interaction of shock waves could be considered an important source for production of new turbulence or for the enhancement of pre-existing turbulence. Individual papers are processed separately.

  15. Energy spectra in bubbly turbulence

    E-Print Network [OSTI]

    Prakash, Vivek N; Ramos, Fabio Ernesto Mancilla; Tagawa, Yoshiyuki; Lohse, Detlef; Sun, Chao

    2013-01-01

    We conduct experiments in a turbulent bubbly flow to study the unknown nature of the transition between the classical -5/3 energy spectrum scaling for a single-phase turbulent flow and the -3 scaling for a swarm of bubbles rising in a quiescent liquid and of bubble-dominated turbulence. The bubblance parameter, b, which measures the ratio of the bubble-induced kinetic energy to the kinetic energy induced by the turbulent liquid fluctuations before bubble injection, is used to characterise the bubbly flow. We vary b from $b = \\infty$ (pseudo-turbulence) to b = 0 (single-phase flow) over 2-3 orders of magnitude: ~O(0.01, 0.1, 5) to study its effect on the turbulent energy spectrum and liquid velocity fluctuations. The experiments are conducted in a multi-phase turbulent water tunnel with air bubbles of diameters 2-4 mm and 3-5 mm. An active-grid is used to generate nearly homogeneous and isotropic turbulence in the liquid flow. The liquid speeds and gas void fractions are varied to achieve the above mentioned b...

  16. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect (OSTI)

    Chang, C.H.

    1992-01-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  17. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect (OSTI)

    Chang, C.H.

    1992-08-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  18. Particle Multiplicity in Jets and Sub-jets with Jet Axis from Color Current

    E-Print Network [OSTI]

    Wlofgang Ochs; Redamy Perez Ramos

    2008-07-07

    We study the particle multiplicity in a jet or sub-jet as derived from an energy-multiplicity 2-particle correlation. This definition avoids the notion of a globally fixed jet axis and allows for the study of smaller jet cone openings in a more stable way. The results are sensitive to the mean color current $_{A_0} $ in the jet from primary parton $A_0$ which takes into account intermediate partonic processes in the sub-jet production where $C_F_{A_0} jet axis definition are computed for multiplicities in sub-jets with different opening angles and energies by including contributions from the Modified LLA (MLLA) and Next-to-MLLA to the leading order QCD results.

  19. High-Pressure Turbulent Flame Speeds and Chemical Kinetics of Syngas Blends with and without Impurities

    SciTech Connect (OSTI)

    Peterson, Eric; Mathieu, Olivier; Morones, Anibal; Ravi, Sankar; Keesee, Charles; Hargis, Joshua; Vivanco, Jose

    2014-12-01

    This Topical Report documents the first year of the project, from October 1, 2013 through September 30, 2014. Efforts for this project included experiments to characterize the atmospheric-pressure turbulent flame speed vessel over a range of operating conditions (fan speeds and turbulent length scales). To this end, a new LDV system was acquired and set up for the detailed characterization of the turbulence field. Much progress was made in the area of impurity kinetics, which included a numerical study of the effect of impurities such as NO2, NO, H2S, and NH3 on ignition delay times and laminar flame speeds of syngas blends at engine conditions. Experiments included a series of laminar flame speed measurements for syngas (CO/H2) blends with various levels of CH4 and C2H6 addition, and the results were compared to the chemical kinetics model of NUI Galway. Also, a final NOx kinetics mechanism including ammonia was assembled, and a journal paper was written and is now in press. Overall, three journal papers and six conference papers related to this project were published this year. Finally, much progress was made on the design of the new high-pressure turbulent flame speed facility. An overall design that includes a venting system was decided upon, and the detailed design is in progress.

  20. BARYON LOADING OF ACTIVE GALACTIC NUCLEUS JETS MEDIATED BY NEUTRONS

    SciTech Connect (OSTI)

    Toma, K.; Takahara, F.

    2012-08-01

    Plasmas of geometrically thick, black hole (BH) accretion flows in active galactic nuclei (AGNs) are generally collisionless for protons, and involve magnetic field turbulence. Under such conditions a fraction of protons can be accelerated stochastically and create relativistic neutrons via nuclear collisions. These neutrons can freely escape from the accretion flow and decay into protons in the dilute polar region above the rotating BH to form relativistic jets. We calculate geometric efficiencies of the neutron energy and mass injections into the polar region, and show that this process can deposit luminosity as high as L{sub j}{approx}2 Multiplication-Sign 10{sup -3} M-dot c{sup 2} and mass loading M-dot{sub j}{approx}6 Multiplication-Sign 10{sup -4} M-dot for the case of the BH mass M {approx} 10{sup 8} M{sub Sun }, where M-dot is the mass accretion rate. The terminal Lorentz factors of the jets are {Gamma} {approx} 3, and they may explain the AGN jets having low luminosities. For higher luminosity jets, which can be produced by additional energy inputs such as Poynting flux, the neutron decay still can be a dominant mass loading process, leading to, e.g., {Gamma} {approx} 50 for L{sub j,tot}{approx}3 Multiplication-Sign 10{sup -2} M-dot c{sup 2}.

  1. Detailed Chemical Kinetic Reaction Mechanisms for Primary Reference Fuels for Diesel Cetane Number and Spark-Ignition Octane Number

    SciTech Connect (OSTI)

    Westbrook, C K; Pitz, W J; Mehl, M; Curran, H J

    2010-03-03

    For the first time, a detailed chemical kinetic reaction mechanism is developed for primary reference fuel mixtures of n-hexadecane and 2,2,4,4,6,8,8-heptamethyl nonane for diesel cetane ratings. The mechanisms are constructed using existing rules for reaction pathways and rate expressions developed previously for the primary reference fuels for gasoline octane ratings, n-heptane and iso-octane. These reaction mechanisms are validated by comparisons between computed and experimental results for shock tube ignition and for oxidation under jet-stirred reactor conditions. The combined kinetic reaction mechanism contains the submechanisms for the primary reference fuels for diesel cetane ratings and submechanisms for the primary reference fuels for gasoline octane ratings, all in one integrated large kinetic reaction mechanism. Representative applications of this mechanism to two test problems are presented, one describing fuel/air autoignition variations with changes in fuel cetane numbers, and the other describing fuel combustion in a jet-stirred reactor environment with the fuel varying from pure 2,2,4,4,6,8,8-heptamethyl nonane (Cetane number of 15) to pure n-hexadecane (Cetane number of 100). The final reaction mechanism for the primary reference fuels for diesel fuel and gasoline is available on the web.

  2. Instabilities of rotating jets

    E-Print Network [OSTI]

    Zahniser, Russell, 1982-

    2004-01-01

    When a jet of water is in free fall, it rapidly breaks up into drops, since a cylinder of water is unstable. This and other problems involving the form of a volume of water bound by surface tension have yielded a wealth ...

  3. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  4. Hadron Correlation in Jets

    E-Print Network [OSTI]

    Rudolph C. Hwa

    2007-01-18

    We review some recent experimental and theoretical work on the correlation among hadrons produced at intermediate $p_T$ at RHIC. The topics include: forward and backward asymmetry with and without trigger at mid-rapidity, associated-particle distribution on the near side, the $\\Omega$ puzzle and its solution, associated particles on the away side, and two-jet recombination at LHC.

  5. The Effect of Magnetic Turbulence Energy Spectral

    E-Print Network [OSTI]

    Ng, Chung-Sang

    The Effect of Magnetic Turbulence Energy Spectral Scaling on the Heating of the Solar Wind C. S. Ng), Kraichnan (1965) #12;Solar wind turbulence model The steady state solar wind turbulence model developed wind with uniform speed Vsw 1D (radial position r) Turbulence characterized by two fields

  6. Interacting Jets from Binary Protostars

    E-Print Network [OSTI]

    G. C. Murphy; T. Lery; S. O'Sullivan; D. Spicer; F. Bacciotti; A. Rosen

    2007-11-20

    We investigate potential models that could explain why multiple proto-stellar systems predominantly show single jets. During their formation, stars most frequently produce energetic outflows and jets. However, binary jets have only been observed in a very small number of systems. We model numerically 3D binary jets for various outflow parameters. We also model the propagation of jets from a specific source, namely L1551 IRS 5, known to have two jets, using recent observations as constraints for simulations with a new MHD code. We examine their morphology and dynamics, and produce synthetic emission maps. We find that the two jets interfere up to the stage where one of them is almost destroyed or engulfed into the second one. We are able to reproduce some of the observational features of L1551 such as the bending of the secondary jet. While the effects of orbital motion are negligible over the jets dynamical timeline, their interaction has significant impact on their morphology. If the jets are not strictly parallel, as in most observed cases, we show that the magnetic field can help the collimation and refocusing of both of the two jets.

  7. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    SciTech Connect (OSTI)

    Federrath, Christoph; Schober, Jennifer; Bovino, Stefano; Schleicher, Dominik R. G.

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ?/? = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ? 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub ?31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  8. Flow cytometer jet monitor system

    DOE Patents [OSTI]

    Van den Engh, Ger (Seattle, WA)

    1997-01-01

    A direct jet monitor illuminates the jet of a flow cytometer in a monitor wavelength band which is substantially separate from the substance wavelength band. When a laser is used to cause fluorescence of the substance, it may be appropriate to use an infrared source to illuminate the jet and thus optically monitor the conditions within the jet through a CCD camera or the like. This optical monitoring may be provided to some type of controller or feedback system which automatically changes either the horizontal location of the jet, the point at which droplet separation occurs, or some other condition within the jet in order to maintain optimum conditions. The direct jet monitor may be operated simultaneously with the substance property sensing and analysis system so that continuous monitoring may be achieved without interfering with the substance data gathering and may be configured so as to allow the front of the analysis or free fall area to be unobstructed during processing.

  9. Memory effects in turbulent transport

    E-Print Network [OSTI]

    Alexander Hubbard; Axel Brandenburg

    2009-11-13

    In the mean-field theory of magnetic fields, turbulent transport, i.e. the turbulent electromotive force, is described by a combination of the alpha effect and turbulent magnetic diffusion, which are usually assumed to be proportional respectively to the mean field and its spatial derivatives. For a passive scalar there is just turbulent diffusion, where the mean flux of concentration depends on the gradient of the mean concentration. However, these proportionalities are approximations that are valid only if the mean field or the mean concentration vary slowly in time. Examples are presented where turbulent transport possesses memory, i.e. where it depends crucially on the past history of the mean field. Such effects are captured by replacing turbulent transport coefficients with time integral kernels, resulting in transport coefficients that depend effectively on the frequency or the growth rate of the mean field itself. In this paper we perform numerical experiments to find the characteristic timescale (or memory length) of this effect as well as simple analytical models of the integral kernels in the case of passive scalar concentrations and kinematic dynamos. The integral kernels can then be used to find self-consistent growth or decay rates of the mean fields. In mean-field dynamos the growth rates and cycle periods based on steady state values of alpha effect and turbulent diffusivity can be quite different from the actual values.

  10. Nuclear diagnostics for the National Ignition Facility (invited)

    SciTech Connect (OSTI)

    Murphy, Thomas J.; Barnes, Cris W.; Berggren, R. R.; Bradley, P.; Caldwell, S. E.; Chrien, R. E.; Faulkner, J. R.; Gobby, P. L.; Hoffman, N.; Jimerson, J. L.

    2001-01-01

    The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, will provide unprecedented opportunities for the use of nuclear diagnostics in inertial confinement fusion experiments. The completed facility will provide 2 MJ of laser energy for driving targets, compared to the approximately 40 kJ that was available on Nova and the approximately 30 kJ available on Omega. Ignited NIF targets are anticipated to produce up to 10{sup 19} DT neutrons. In addition to a basic set of nuclear diagnostics based on previous experience, these higher NIF yields are expected to allow innovative nuclear diagnostic techniques to be utilized, such as neutron imaging, recoil proton techniques, and gamma-ray-based reaction history measurements.

  11. Inertial Confinement Fusion and the National Ignition Facility (NIF)

    SciTech Connect (OSTI)

    Ross, P.

    2012-08-29

    Inertial confinement fusion (ICF) seeks to provide sustainable fusion energy by compressing frozen deuterium and tritium fuel to extremely high densities. The advantages of fusion vs. fission are discussed, including total energy per reaction and energy per nucleon. The Lawson Criterion, defining the requirements for ignition, is derived and explained. Different confinement methods and their implications are discussed. The feasibility of creating a power plant using ICF is analyzed using realistic and feasible numbers. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is shown as a significant step forward toward making a fusion power plant based on ICF. NIF is the world’s largest laser, delivering 1.8 MJ of energy, with a peak power greater than 500 TW. NIF is actively striving toward the goal of fusion energy. Other uses for NIF are discussed.

  12. Final report for miniature laser ignited bellows motor

    SciTech Connect (OSTI)

    Renfro, S.L.

    1994-02-18

    A miniature optically ignited actuation device has been demonstrated using a laser diode as an ignition source. This pyrotechnic driven motor provides between 4 and 6 lbs of linear force across a 0.090 inch diameter surface. The physical envelope of the device is 1/2 inch long and 1/8 inch diameter. This unique application of optical energy can be used as a mechanical link in optical arming systems or other applications where low shock actuation is desired and space is limited. An analysis was performed to determine pyrotechnic materials suitable to actuate a bellows device constructed of aluminum or stainless steel. The aluminum bellows was chosen for further development and several candidate pyrotechnics were evaluated. The velocity profile and delivered force were quantified using an non-intrusive optical motion sensor.

  13. Hydrodynamic instabilities in beryllium targets for the National Ignition Facility

    SciTech Connect (OSTI)

    Yi, S. A., E-mail: austinyi@lanl.gov; Simakov, A. N.; Wilson, D. C.; Olson, R. E.; Kline, J. L.; Batha, S. H. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States); Clark, D. S.; Hammel, B. A.; Milovich, J. L.; Salmonson, J. D.; Kozioziemski, B. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

    2014-09-15

    Beryllium ablators offer higher ablation velocity, rate, and pressure than their carbon-based counterparts, with the potential to increase the probability of achieving ignition at the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)]. We present here a detailed hydrodynamic stability analysis of low (NIF Revision 6.1) and high adiabat NIF beryllium target designs. Our targets are optimized to fully utilize the advantages of beryllium in order to suppress the growth of hydrodynamic instabilities. This results in an implosion that resists breakup of the capsule, and simultaneously minimizes the amount of ablator material mixed into the fuel. We quantify the improvement in stability of beryllium targets relative to plastic ones, and show that a low adiabat beryllium capsule can be at least as stable at the ablation front as a high adiabat plastic target.

  14. Compound cooling flow turbulator for turbine component

    DOE Patents [OSTI]

    Lee, Ching-Pang; Jiang, Nan; Marra, John J; Rudolph, Ronald J

    2014-11-25

    Multi-scale turbulation features, including first turbulators (46, 48) on a cooling surface (44), and smaller turbulators (52, 54, 58, 62) on the first turbulators. The first turbulators may be formed between larger turbulators (50). The first turbulators may be alternating ridges (46) and valleys (48). The smaller turbulators may be concave surface features such as dimples (62) and grooves (54), and/or convex surface features such as bumps (58) and smaller ridges (52). An embodiment with convex turbulators (52, 58) in the valleys (48) and concave turbulators (54, 62) on the ridges (46) increases the cooling surface area, reduces boundary layer separation, avoids coolant shadowing and stagnation, and reduces component mass.

  15. High load operation in a homogeneous charge compression ignition engine

    DOE Patents [OSTI]

    Duffy, Kevin P. (Metamora, IL); Kieser, Andrew J. (Morton, IL); Liechty, Michael P. (Chillicothe, IL); Hardy, William L. (Peoria, IL); Rodman, Anthony (Chillicothe, IL); Hergart, Carl-Anders (Peoria, IL)

    2008-12-23

    A homogeneous charge compression ignition engine is set up by first identifying combinations of compression ratio and exhaust gas percentages for each speed and load across the engines operating range. These identified ratios and exhaust gas percentages can then be converted into geometric compression ratio controller settings and exhaust gas recirculation rate controller settings that are mapped against speed and load, and made available to the electronic

  16. Wave Decay in MHD Turbulence

    E-Print Network [OSTI]

    Andrey Beresnyak; Alex Lazarian

    2008-05-06

    We present a model for nonlinear decay of the weak wave in three-dimensional incompressible magnetohydrodynamic (MHD) turbulence. We show that the decay rate is different for parallel and perpendicular waves. We provide a general formula for arbitrarily directed waves and discuss particular limiting cases known in the literature. We test our predictions with direct numerical simulations of wave decay in three-dimensional MHD turbulence, and discuss the influence of turbulent damping on the development of linear instabilities in the interstellar medium and on other important astrophysical processes.

  17. The National Ignition Facility: Studying the Stars in the Laboratory

    SciTech Connect (OSTI)

    Boyd, R

    2008-09-17

    The National Ignition Facility, to be completed in 2009, will be the highest energy laser ever built. The high temperatures and densities it will produce will enable a number of experiments in inertial confinement fusion and stockpile stewardship, as well as in nuclear astrophysics, X-ray astronomy, hydrodynamics, and planetary science. The National Ignition Facility, NIF (1), located at Lawrence Livermore National Lab, (LLNL) is expected to produce inertial confinement fusion (ICF) by delivering sufficient laser energy to compress and heat a millimeter-radius pellet of DT sufficiently to produce fusion to {sup 4}He+neutron and 17.6 MeV per reaction. NIF will be completed by March, 2009, at which time a National Ignition Campaign (2), NIC, a series of experiments to optimize the ICF parameters, will begin. Although NIF is a research facility, a successful NIC would have implications for future energy sources. In addition to the goal of ICF, NIF will support programs in stockpile stewardship. However, the conditions that NIF creates will simulate those inside stars and planets sufficiently closely to provide compelling motivation for experiments in basic high-energy-density (HED) science especially, for the first time, in nuclear astrophysics.

  18. BIPOLAR JETS LAUNCHED FROM ACCRETION DISKS. II. THE FORMATION OF ASYMMETRIC JETS AND COUNTER JETS

    SciTech Connect (OSTI)

    Fendt, Christian; Sheikhnezami, Somayeh E-mail: nezami@mpia.de

    2013-09-01

    We investigate the jet launching from accretion disks, in particular the formation of intrinsically asymmetric jet/counter jet systems. We perform axisymmetric MHD simulations of the disk-jet structure on a bipolar computational domain covering both hemispheres. We apply various models such as asymmetric disks with (initially) different scale heights in each hemisphere, symmetric disks into which a local disturbance is injected, and jets launched into an asymmetric disk corona. We consider both a standard global magnetic diffusivity distribution and a novel local diffusivity model. Typical disk evolution first shows substantial disk warping and then results in asymmetric outflows with a 10%-30% mass flux difference. We find that the magnetic diffusivity profile is essential for establishing a long-term outflow asymmetry. We conclude that bipolar asymmetry in protostellar and extragalactic jets can indeed be generated intrinsically and maintained over a long time by disk asymmetries and the standard jet launching mechanism.

  19. Pilot fuel ignited stratified charge rotary combustion engine and fuel injector therefor

    SciTech Connect (OSTI)

    Loyd, R. W.

    1980-02-12

    For a pilot fuel ignited stratified charge rotary, internal combustion engine, the fuel injection system and a fuel injector therefor comprises a fuel injector having plural discharge ports with at least one of the discharge ports located to emit a ''pilot'' fuel charge (relatively rich fuel-air mixture) into a passage in the engine housing, which passage communicates with the engine combustion chambers. An ignition element is located in the passage to ignite the ''pilot'' fuel (a relatively rich fuel-air mixture) flowing through the passage. At least one other discharge port of the fuel injector is in substantially direct communication with the combustion chambers of the engine to emit a main fuel charge into the latter. The ignited ''pilot'' fuelair mixture, when ignited, flashes into the combustion chambers to ignite the main, relatively lean, fuel-air mixture which is in the combustion chambers.

  20. Using laser entrance hole shields to increase coupling efficiency in indirect drive ignition targets for the National Ignition Facility

    SciTech Connect (OSTI)

    Callahan, D.A.; Amendt, P.A.; Dewald, E.L.; Haan, S.W.; Hinkel, D.E.; Izurni, N.; Jones, O.S.; Landen, O.L.; Lindl, J.D.; Pollaine, S.M.; Suter, L.J.; Tabak, M.; Turner, R.E. [Lawrence Livermore National Laboratory, P.O. Box 808, Mail stop L-015, Livermore, California 94550 (United States)

    2006-05-15

    Coupling efficiency, the ratio of the capsule absorbed energy to the driver energy, is a key parameter in ignition target designs. The hohlraum originally proposed for the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, S228 (2004)] coupled {approx}11% of the absorbed laser energy to the capsule as x rays. Described here is a second generation of the hohlraum target which has a higher coupling efficiency, {approx}16%. Because the ignition capsule's ability to withstand three-dimensional effects increases rapidly with absorbed energy, the additional energy can significantly increase the likelihood of ignition. The new target includes laser entrance hole (LEH) shields as a principal method for increasing coupling efficiency while controlling symmetry in indirect-drive inertial confinement fusion. The LEH shields are high Z disks placed inside the hohlraum on the symmetry axis to block the capsule's view of the relatively cold LEHs. The LEH shields can reduce the amount of laser energy required to drive a target to a given temperature via two mechanisms: (1) keeping the temperature high near the capsule pole by putting a barrier between the capsule and the pole; (2) because the capsule pole does not have a view of the cold LEHs, good symmetry requires a shorter hohlraum with less wall area. Current integrated simulations of this class of target couple 140 kJ of x rays to a capsule out of 865 kJ of absorbed laser energy and produce {approx}10 MJ of yield. In the current designs, which continue to be optimized, the addition of the LEH shields saves {approx}95 kJ of energy (about 10%) over hohlraums without LEH shields.

  1. Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature

    SciTech Connect (OSTI)

    Choi, B.C.; Chung, S.H.

    2010-12-15

    The autoignition characteristics of laminar lifted flames of methane, ethylene, ethane, and n-butane fuels have been investigated experimentally in coflow air with elevated temperature over 800 K. The lifted flames were categorized into three regimes depending on the initial temperature and fuel mole fraction: (1) non-autoignited lifted flame, (2) autoignited lifted flame with tribrachial (or triple) edge, and (3) autoignited lifted flame with mild combustion. For the non-autoignited lifted flames at relatively low temperature, the existence of lifted flame depended on the Schmidt number of fuel, such that only the fuels with Sc > 1 exhibited stationary lifted flames. The balance mechanism between the propagation speed of tribrachial flame and local flow velocity stabilized the lifted flames. At relatively high initial temperatures, either autoignited lifted flames having tribrachial edge or autoignited lifted flames with mild combustion existed regardless of the Schmidt number of fuel. The adiabatic ignition delay time played a crucial role for the stabilization of autoignited flames. Especially, heat loss during the ignition process should be accounted for, such that the characteristic convection time, defined by the autoignition height divided by jet velocity was correlated well with the square of the adiabatic ignition delay time for the critical autoignition conditions. The liftoff height was also correlated well with the square of the adiabatic ignition delay time. (author)

  2. Conversion of relativistic pair energy into radiation in the jets of active galactic nuclei

    E-Print Network [OSTI]

    R. Schlickeiser; R. Vainio; M. Boettcher; I. Lerche; M. Pohl; C. Schuster

    2002-07-02

    It is generally accepted that relativistic jet outflows power the nonthermal emission from active galactic nuclei (AGN). The composition of these jets -- leptonic versus hadronic -- is still under debate. We investigate the microphysical details of the conversion process of the kinetic energy in collimated relativistic pair outflows into radiation through interactions with the ambient interstellar medium. Viewed from the coordinate system comoving with the pair outflow, the interstellar protons and electrons represent a proton-electron beam propagating with relativistic speed in the pair plasma. We demonstrate that the beam excites both electrostatic and low-frequency magnetohydrodynamic Alfven-type waves via a two-stream instability in the pair background plasma, and we calculate the time evolution of the distribution functions of the beam particles and the generated plasma wave turbulence power spectra. For standard AGN jet outflow and environment parameters we show that the initial beam distributions of interstellar protons and electrons quickly relax to plateau-distributions in parallel momentum, transferring thereby one-half of the initial energy density of the beam particles to electric field fluctuations of the generated electrostatic turbulence. On considerably longer time scales, the plateaued interstellar electrons and protons will isotropise by their self-generated transverse turbulence and thus be picked-up in the outflow pair plasma. These longer time scales are also characteristic for the development of transverse hydromagnetic turbulence from the plateaued electrons and protons. This hydromagnetic turbulence upstream and downstream is crucial for diffusive shock acceleration to operate at external or internal shocks associated with pair outflows.

  3. Ram jet engine

    SciTech Connect (OSTI)

    Crispin, B.; Pohl, W.D.; Thomaier, D.; Voss, N.

    1983-11-29

    In a ram jet engine, a tubular combustion chamber is divided into a flame chamber followed by a mixing chamber. The ram air is supplied through intake diffusers located on the exterior of the combustion chamber. The intake diffusers supply combustion air directly into the flame chamber and secondary air is conveyed along the exterior of the combustion chambers and then supplied directly into the mixing chamber.

  4. Two-stage ignition and NTC phenomenon in diesel engines Xiao Fu, Suresh K. Aggarwal

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    investigated in sprays and homogeneous mixtures. Effect of methane on the ignition of n-heptane sprays in dual-fuel-stage ignition NTC phenomenon Diesel spray Dual-fuel engine a b s t r a c t Two-stage ignition and NTC phenomenon in diesel sprays is investigated by performing 3-D two-phase reacting flow simulations in a dual-fuel engine

  5. Beam/Jet Trajectories April 1, 2009

    E-Print Network [OSTI]

    McDonald, Kirk

    Beam/Jet Trajectories April 1, 2009 #12;Hg Jet Target Geometry Solenoid Axis Hg Jet Proton Beam BEAM CROSS rJET Previous results: Radius 5mm, beam =67mrad crossing = 33mrad #12;Optimized Target Energy, GeV Optimized Target Radius #12;Beam Angle and Jet/Beam Crossing Angle 0 20 40 60 80 100 120 140

  6. JET Forward Programme & Opportunities for Collaboration

    E-Print Network [OSTI]

    JET Forward Programme & Opportunities for Collaboration Lorne Horton JET Exploitation Manager Contract for the Opera.on of the JET Facili.es Co-Funded by Euratom #12;L.D. Horton 2 FESAC Strategic Planning Panel 8 July 2014 - What makes JET unique! - Plans for JET exploitation

  7. Effect of ambient conditions and fuel properties on homogeneous charge compression ignition engine operation

    E-Print Network [OSTI]

    Andreae, Morgan M. (Morgan MacKenzie)

    2006-01-01

    Practical application of Homogeneous Charge Compression Ignition (HCCI) combustion must demonstrate robust responses to variations in environmental conditions. This work examines the impact of ambient conditions and fuel ...

  8. Investigation of proton focusing and conversion efficiency for proton fast ignition

    E-Print Network [OSTI]

    Bartal, Teresa Jean

    2012-01-01

    After ignition, a thermonuclear burn wave spreads radiallythe shell to create the thermonuclear burn wave. At 10 keV,heating the plasma to thermonuclear temperatures. Protons

  9. Modeling the Number of Ignitions Following an Earthquake: Developing Prediction Limits for Overdispersed Count Data

    Broader source: Energy.gov [DOE]

    Modeling the Number of Ignitions Following an Earthquake: Developing Prediction Limits for Overdispersed Count Data Elizabeth J. Kelly and Raymond N. Tell

  10. Control strategy for hydrocarbon emissions in turbocharged direct injection spark ignition engines during cold-start

    E-Print Network [OSTI]

    Cedrone, Kevin David

    2013-01-01

    Gasoline consumption and pollutant emissions from transportation are costly and have serious, demonstrated environmental and health impacts. Downsized, turbocharged direct-injection spark ignition (DISI) gasoline engines ...

  11. Status of and prospects for the fast ignition inertial fusion concept

    SciTech Connect (OSTI)

    Key, M. H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2007-05-15

    Fast ignition is an alternate concept in inertial confinement fusion, which has the potential for easier ignition and greater energy multiplication. If realized, it could improve the prospects for inertial fusion energy. It poses stimulating challenges in science and technology, and the research is approaching a key stage in which the feasibility of fast ignition will be determined. This review covers the concepts, the state of the science and technology, the near-term prospects, and the challenges and risks involved in demonstrating high-gain fast ignition.

  12. Selected Items in Jet Algorithms

    E-Print Network [OSTI]

    Giuseppe Bozzi

    2008-08-06

    I provide a very brief overview of recent developments in jet algorithms, mostly focusing on the issue of infrared-safety.

  13. Photon + jets at D0

    E-Print Network [OSTI]

    Lars Sonnenschein

    2009-06-15

    Photon plus jet production has been studied by the D0 experiment in Run II of the Fermilab Tevatron Collider at a centre of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon, inclusive photon plus jet, photon plus heavy flavour jet cross sections and double parton interactions in photon plus three jet events are presented. They are based on integrated luminosities between 0.4 fb$^-1 and 1.0 fb^-1. The results are compared to perturbative QCD calculations in various approximations.

  14. Turbulent AGN tori

    E-Print Network [OSTI]

    M. Schartmann; K. Meisenheimer; H. Klahr; M. Camenzind; S. Wolf; Th. Henning

    2008-08-05

    Recently, the MID-infrared Interferometric instrument (MIDI) at the VLTI has shown that dust tori in the two nearby Seyfert galaxies NGC 1068 and the Circinus galaxy are geometrically thick and can be well described by a thin, warm central disk, surrounded by a colder and fluffy torus component. By carrying out hydrodynamical simulations with the help of the TRAMP code (Klahr et al. 1999), we follow the evolution of a young nuclear star cluster in terms of discrete mass-loss and energy injection from stellar processes. This naturally leads to a filamentary large scale torus component, where cold gas is able to flow radially inwards. The filaments open out into a dense and very turbulent disk structure. In a post-processing step, we calculate observable quantities like spectral energy distributions or images with the help of the 3D radiative transfer code MC3D (Wolf 2003). Good agreement is found in comparisons with data due to the existence of almost dust-free lines of sight through the large scale component and the large column densities caused by the dense disk.

  15. Buoyant jet behavior in confined regions

    E-Print Network [OSTI]

    Fry, David J.

    1981-01-01

    Previous confined jet studies have emphasized the behavior of non-buoyant jets inside ducts or near plane boundaries (Coanda effect). Buoyancy, however, is a major factor in the confined jet behavior experienced in many ...

  16. Jet shapes with the broadening axis

    E-Print Network [OSTI]

    Larkoski, Andrew James

    Broadening is a classic jet observable that probes the transverse momentum structure of jets. Traditionally, broadening has been measured with respect to the thrust axis, which is aligned along the (hemisphere) jet momentum ...

  17. Miniconference on astrophysical jets P. M. Bellan

    E-Print Network [OSTI]

    Bellan, Paul M.

    Miniconference on astrophysical jets P. M. Bellan Applied Physics, California Institute 9 May 2005 This miniconference brought together observers of astrophysical jets, analytic and numerical modelers of both astrophysical jets and spheromaks, and laboratory experimentalists. The purpose

  18. JETS IN e+e- ANNIHILATION

    E-Print Network [OSTI]

    Cooper, Susan Catherine.

    2010-01-01

    io U s, Data Monte Carlo, ~zz Jet Model Monte Carlo, - Phaseener-jy for data (points), jet model (solid curve) and pnaotAXIS The quarKs and hence the jet axis should have the same

  19. On impinging near-field granular jets

    E-Print Network [OSTI]

    Arbelaez, D.; Zohdi, T. I.; Dornfeld, D. A.

    2009-01-01

    evolution models in abrasive jet micromachining. Wear 2008;SIMULATION OF GRANULAR JETS 26. Cheng X, Varas G, Citron D,behavior in a granular jet: emergence of a liquid with zero

  20. Searching for Jets in Heavy Ion Collisions

    E-Print Network [OSTI]

    Salur, Sevil

    2008-01-01

    measurements with full jet reconstruction in heavy ionDirect measurement of jets in s N N = 200 GeV Heavy Ion5–12, 2008 Searching for Jets in Heavy Ion Collisions Sevil

  1. Control of a high Reynolds number Mach 0.9 heated jet using plasma actuators

    SciTech Connect (OSTI)

    Kearney-Fischer, M.; Kim, J.-H.; Samimy, M.

    2009-09-15

    The results of particle image velocimetry (PIV) measurements in a high subsonic, heated, jet forced using localized arc filament plasma actuators (LAFPAs) show that LAFPAs can consistently produce significant mixing enhancement over a wide range of temperatures. These actuators have been used successfully in high Reynolds number, high-speed unheated jets. The facility consists of an axisymmetric jet with different nozzle blocks of exit diameter of 2.54 cm and variable jet temperature in an anechoic chamber. The focus of this paper is on a high subsonic (M{sub j}=0.9) jet. Twelve experiments with various forcing azimuthal modes (m=0, 1, and {+-}1) and temperatures (T{sub o}/T{sub a}=1.0, 1.4, and 2.0) at a fixed forcing Strouhal number (St{sub DF}=0.3) have been conducted and PIV results compared with the baseline results to characterize the effectiveness of LAFPAs for mixing enhancement. Centerline velocity and turbulent kinetic energy as well as jet width are used for determining the LAFPAs' effectiveness. The characteristics of large-scale structures are analyzed through the use of Galilean streamlines and swirling strength. Across the range of temperatures collected, the effectiveness of LAFPAs improves as temperature increases. Possible reasons for the increase in effectiveness are discussed.

  2. Expansion of a radial jet from a guillotine tube breach in a shell-and-tube heat exchanger

    SciTech Connect (OSTI)

    Velasco, F.J.S.; del Pra, C. Lopez; Herranz, Luis E. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Nuclear fission division, Nuclear Safety Research Unit, Avda. Complutense, 22, P.O. Box 28040 Madrid (Spain)

    2008-02-15

    Aerodynamics of a particle-laden gas jet entering the secondary side of a shell-and-tube heat exchanger from a tube guillotine breach, determines to a large extent radioactive retention in the break stage of the steam generator (SG) during hypothetical SGTR accident sequences in pressurized nuclear water reactors (PWRs). These scenarios were shown to be risk-dominant in PWRs. The major insights gained from a set of experiments into such aerodynamics are summarized in this paper. A scaled-down mock-up with representative dimensions of a real SG was built. Two-dimensional (2D) PIV technique was used to characterize the flow field in the space between the breach and the neighbor tubes in the gas flow range investigated (Re{sub D} = 0.8-2.7 x 10{sup 5}). Pitot tube measurements and CFD simulations were used to discuss and complement PIV data. The results, reported mainly in terms of velocity and turbulent intensity profiles, show that jet penetration and gas entrainment are considerably enhanced when increasing Re{sub D}. The presence of tubes was observed to distort the jet shape and to foster gas entrainment with respect to a jet expansion free of tubes. Turbulence intensity level close to the breach increases linearly with Re{sub D}. Account of this information into aerosol modeling will enhance predictive capability of inertial impaction and turbulent deposition equations. (author)

  3. The ePLAS Code for Ignition Studies

    SciTech Connect (OSTI)

    Mason, Rodney J

    2012-09-20

    Inertial Confinement Fusion (ICF) presents unique opportunities for the extraction of clean energy from Fusion. Intense lasers and particle beams can create and interact with such plasmas, potentially yielding sufficient energy to satisfy all our national needs. However, few models are available to help aid the scientific community in the study and optimization of such interactions. This project enhanced and disseminated the computer code ePLAS for the early understanding and control of Ignition in ICF. ePLAS is a unique simulation code that tracks the transport of laser light to a target, the absorption of that light resulting in the generation and transport of hot electrons, and the heating and flow dynamics of the background plasma. It uses an implicit electromagnetic field-solving method to greatly reduce computing demands, so that useful target interaction studies can often be completed in 15 minutes on a portable 2.1 GHz PC. The code permits the rapid scoping of calculations for the optimization of laser target interactions aimed at fusion. Recent efforts have initiated the use of analytic equations of state (EOS), K-alpha image rendering graphics, allocatable memory for source-free usage, and adaption to the latest Mac and Linux Operating Systems. The speed and utility of ePLAS are unequaled in the ICF simulation community. This project evaluated the effects of its new EOSs on target heating, compared fluid and particle models for the ions, initiated the simultaneous use of both ion models in the code, and studied long time scale 500 ps hot electron deposition for shock ignition. ePLAS has been granted EAR99 export control status, permitting export without a license to most foreign countries. Beta-test versions of ePLAS have been granted to several Universities and Commercial users. The net Project was aimed at achieving early success in the laboratory ignition of thermonuclear targets and the mastery of controlled fusion power for the nation.

  4. Conversion of relativistic pair energy into radiation in the jets of active galactic nuclei

    E-Print Network [OSTI]

    Schlickeiser, R; Böttcher, M; Lerche, I; Pohl, M; Schuster, C

    2002-01-01

    It is generally accepted that relativistic jet outflows power the nonthermal emission from active galactic nuclei (AGN). The composition of these jets -- leptonic versus hadronic -- is still under debate. We investigate the microphysical details of the conversion process of the kinetic energy in collimated relativistic pair outflows into radiation through interactions with the ambient interstellar medium. Viewed from the coordinate system comoving with the pair outflow, the interstellar protons and electrons represent a proton-electron beam propagating with relativistic speed in the pair plasma. We demonstrate that the beam excites both electrostatic and low-frequency magnetohydrodynamic Alfven-type waves via a two-stream instability in the pair background plasma, and we calculate the time evolution of the distribution functions of the beam particles and the generated plasma wave turbulence power spectra. For standard AGN jet outflow and environment parameters we show that the initial beam distributions of in...

  5. Controlling And Operating Homogeneous Charge Compression Ignition (Hcci) Engines

    DOE Patents [OSTI]

    Flowers, Daniel L. (San Leandro, CA)

    2005-08-02

    A Homogeneous Charge Compression Ignition (HCCI) engine system includes an engine that produces exhaust gas. A vaporization means vaporizes fuel for the engine an air induction means provides air for the engine. An exhaust gas recirculation means recirculates the exhaust gas. A blending means blends the vaporized fuel, the exhaust gas, and the air. An induction means inducts the blended vaporized fuel, exhaust gas, and air into the engine. A control means controls the blending of the vaporized fuel, the exhaust gas, and the air and for controls the inducting the blended vaporized fuel, exhaust gas, and air into the engine.

  6. Ethane ignition and oxidation behind reflected shock waves

    SciTech Connect (OSTI)

    de Vries, Jaap; Hall, Joel M.; Simmons, Stefanie L.; Kalitan, Danielle M.; Petersen, Eric L.; Rickard, Matthew J.A.

    2007-07-15

    Several diluted C{sub 2}H{sub 6}/O{sub 2}/Ar mixtures of varying concentrations and equivalence ratios (0.5<{phi}<2.0) were studied at temperatures between 1218 and 1860 K and at pressures between 0.57 and 3.0 atm using a shock tube. The argon dilution ranged from 91 to 98% by volume. Reaction progress was monitored using chemiluminescence emission from OH{sup *} and CH{sup *} at 307 and 431 nm, respectively. The dependence of ignition delay time on temperature, activation energy, and reactant concentrations is given in a master correlation of all the experimental data. The overall activation energy was found to be 39.6 kcal/mol over the range of conditions studied. For the first time in a shock-tube C{sub 2}H{sub 6} oxidation study, detailed species profile data and quantitative OH{sup *} time histories were documented, in addition to ignition delay times, and compared against modern detailed mechanisms. Because of the comprehensive scope of the present study and the high precision of the experimental data, several conclusions can be drawn that could not have been reached from earlier studies. Although there is some discrepancy among previous ethane oxidation data, the present work clearly shows the convergence of ignition delay time measurements to those herein and the remarkable accuracy of current kinetics models over most of the parameter space explored, despite the variation in the literature data. However, two areas shown to still need more measurements and better modeling are those of higher pressures and fuel-rich ethane-air mixtures. After appropriate OH{sup *} and CH{sup *} submechanisms are added, two modern chemical kinetics mechanisms containing high-temperature ethane chemistry are compared to the data to gauge the current state of C{sub 2}H{sub 6} oxidation modeling over the conditions of this study. The reproduction of the OH{sup *} and CH{sup *} profiles, together with {tau}{sub ign} predictions by these models, are compared against the profiles and ignition times found in the experimental data. The models are then used to identify some key reactions in ethane oxidation and CH formation under the conditions of this study. (author)

  7. A Kirkpatrick-Baez microscope for the National Ignition Facility

    SciTech Connect (OSTI)

    Pickworth, L. A., E-mail: pickworth1@llnl.gov; McCarville, T.; Decker, T.; Pardini, T.; Ayers, J.; Bell, P.; Bradley, D.; Brejnholt, N. F.; Izumi, N.; Mirkarimi, P.; Pivovaroff, M.; Smalyuk, V.; Vogel, J.; Walton, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Kilkenny, J. [General Atomics, San Diego, California 92121 (United States)

    2014-11-15

    Current pinhole x ray imaging at the National Ignition Facility (NIF) is limited in resolution and signal throughput to the detector for Inertial Confinement Fusion applications, due to the viable range of pinhole sizes (10–25 ?m) that can be deployed. A higher resolution and throughput diagnostic is in development using a Kirkpatrick-Baez microscope system (KBM). The system will achieve <9 ?m resolution over a 300 ?m field of view with a multilayer coating operating at 10.2 keV. Presented here are the first images from the uncoated NIF KBM configuration demonstrating high resolution has been achieved across the full 300 ?m field of view.

  8. Numerical routines for predicting ignition in pyrotechnic devices

    SciTech Connect (OSTI)

    Pierce, K.G.

    1986-06-01

    Two numerical models of the thermal processes leading to ignition in a pyrotechnic device have been developed. These models are based on finite difference approximations to the heat diffusion equation, with temperature-dependent thermal properties, in a single spatial coordinate. The derivation of the finite difference equations is discussed and the methods employed at boundaries and interfaces are given. The sources of the thermal-properties data are identified and how these data are used is explained. The program structure is explained and example runs of the programs are given.

  9. The Neutron Imaging System Fielded at the National Ignition Facility

    SciTech Connect (OSTI)

    Fittinghoff, D N; Atkinson, D P; Bower, D E; Drury, O B; Dzenitis, J M; Felker, B; Frank, M; Liddick, S N; Moran, M J; Roberson, G P; Weiss, P B; Grim, G P; Aragonez, R J; Archuleta, T N; Batha, S H; Clark, D D; Clark, D J; Danly, C R; Day, R D; Fatherley, V E; Finch, J P; Garcia, F P; Gallegos, R A; Guler, N; Hsu, A H; Jaramillo, S A; Loomis, E N; Mares, D; Martinson, D D; Merrill, F E; Morgan, G L; Munson, C; Murphy, T J; Oertel, J A; Polk, P J; Schmidt, D W; Tregillis, I L; Valdez, A C; Volegov, P L; Wang, T F; Wilde, C H; Wilke, M D; Wilson, D C; Buckles, R A; Cradick, J R; Kaufman, M I; Lutz, S S; Malone, R M; Traille, A

    2011-10-24

    We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.

  10. The First Experiments on the National Ignition Facility

    SciTech Connect (OSTI)

    Landen, O L; Glenzer, S; Froula, D; Dewald, E; Suter, L J; Schneider, M; Hinkel, D; Fernandez, J; Kline, J; Goldman, S; Braun, D; Celliers, P; Moon, S; Robey, H; Lanier, N; Glendinning, G; Blue, B; Wilde, B; Jones, O; Schein, J; Divol, L; Kalantar, D; Campbell, K; Holder, J; MacDonald, J; Niemann, C; Mackinnon, A; Collins, R; Bradley, D; Eggert, J; Hicks, D; Gregori, G; Kirkwood, R; Young, B; Foster, J; Hansen, F; Perry, T; Munro, D; Baldis, H; Grim, G; Heeter, R; Hegelich, B; Montgomery, D; Rochau, G; Olson, R; Turner, R; Workman, J; Berger, R; Cohen, B; Kruer, W; Langdon, B; Langer, S; Meezan, N; Rose, H; Still, B; Williams, E; Dodd, E; Edwards, J; Monteil, M; Stevenson, M; Thomas, B; Coker, R; Magelssen, G; Rosen, P; Stry, P; Woods, D; Weber, S; Alvarez, S; Armstrong, G; Bahr, R; Bourgade, J; Bower, D; Celeste, J; Chrisp, M; Compton, S; Cox, J; Constantin, C; Costa, R; Duncan, J; Ellis, A; Emig, J; Gautier, C; Greenwood, A; Griffith, R; Holdner, F; Holtmeier, G; Hargrove, D; James, T; Kamperschroer, J; Kimbrough, J; Landon, M; Lee, D; Malone, R; May, M; Montelongo, S; Moody, J; Ng, E; Nikitin, A; Pellinen, D; Piston, K; Poole, M; Rekow, V; Rhodes, M; Shepherd, R; Shiromizu, S; Voloshin, D; Warrick, A; Watts, P; Weber, F; Young, P; Arnold, P; Atherton, L J; Bardsley, G; Bonanno, R; Borger, T; Bowers, M; Bryant, R; Buckman, S; Burkhart, S; Cooper, F; Dixit, S; Erbert, G; Eder, D; Ehrlich, B; Felker, B; Fornes, J; Frieders, G; Gardner, S; Gates, C; Gonzalez, M; Grace, S; Hall, T; Haynam, C; Heestand, G; Henesian, M; Hermann, M; Hermes, G; Huber, S; Jancaitis, K; Johnson, S; Kauffman, B; Kelleher, T; Kohut, T; Koniges, A E; Labiak, T; Latray, D; Lee, A; Lund, D; Mahavandi, S; Manes, K R; Marshall, C; McBride, J; McCarville, T; McGrew, L; Menapace, J; Mertens, E; Munro, D; Murray, J; Neumann, J; Newton, M; Opsahl, P; Padilla, E; Parham, T; Parrish, G; Petty, C; Polk, M; Powell, C; Reinbachs, I; Rinnert, R; Riordan, B; Ross, G; Robert, V; Tobin, M; Sailors, S; Saunders, R; Schmitt, M; Shaw, M; Singh, M; Spaeth, M; Stephens, A; Tietbohl, G; Tuck, J; Van Wonterghem, B; Vidal, R; Wegner, P; Whitman, P; Williams, K; Winward, K; Work, K

    2005-11-11

    A first set of laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and x-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in flattop and shaped 1-9 ns pulses focused with various beam smoothing options.

  11. Prompt radiochemistry at the National Ignition Facility (invited)

    SciTech Connect (OSTI)

    Grim, G. P.; Bradley, P. A.; Bredeweg, T. A.; Keksis, A. L.; Fowler, M. M.; Hayes, A. C.; Jungman, G.; Obst, A. W.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States); Bernstein, L. A.; Cerjan, C. J.; Fortner, R. J.; Moody, K. J.; Schneider, D. H.; Shaughnessy, D. A.; Stoeffl, W.; Stoyer, M. A. [Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550 (United States)

    2008-10-15

    Understanding mix in inertial confinement fusion (ICF) experiments at the National Ignition Facility requires the diagnosis of charged-particle reactions within an imploded target. Radiochemical diagnostics of these reactions are currently under study by scientists at Los Alamos and Lawrence Livermore National Laboratories. Measurement of these reactions requires assay of activated debris and tracer gases from the target. Presented below is an overview of the prompt radiochemistry diagnostic development efforts, including a discussion of the reactions of interest as well as the progress being made to collect and count activated material.

  12. An enthalpy-temperature hybrid method for solving phase change problems and its application to polymer pyrolysis and ignition

    E-Print Network [OSTI]

    Zhou, Ying-Ying; Fernandez-Pello, Carlos

    2000-01-01

    K.M. , “A Mixed Layer Pyrolysis Model for Polypropylene”, toapplication to polymer pyrolysis and ignition Y. Zhou and A.application to polymer pyrolysis and ignition Y. Zhou and A.

  13. Effect of Turbulence Fluctuations on Surface Heating Rate in Hypersonic Turbulent

    E-Print Network [OSTI]

    Martín, Pino

    Effect of Turbulence Fluctuations on Surface Heating Rate in Hypersonic Turbulent Boundary Layers the effect of turbulence fluctuations on surface heating rate by conducting direct numerical simulations (DNS subtle influence on the mean heating rate. We also find that the effect of turbulence

  14. Effect of Finite-rate Chemical Reactions on Turbulence in Hypersonic Turbulent Boundary Layers

    E-Print Network [OSTI]

    Martín, Pino

    Effect of Finite-rate Chemical Reactions on Turbulence in Hypersonic Turbulent Boundary Layers Lian reaction. The influence of chemical reactions on temperature fluctuation variance, Reynolds stresses that the recombination reaction enhances turbulence, while the dissociation reaction damps turbulence. Chemical reactions

  15. Top Jets at the LHC

    E-Print Network [OSTI]

    Almeida, L.G.

    2009-01-01

    Top Jets at the LHC Leandro G. Almeida, Seung J. Lee, GiladSB-08-37; WIS/17/08-SEPT-DPP Top Jets at the LHC Leandro G.p T hadronically-decaying top quarks at the Large Hadron

  16. OPENING ANGLES OF COLLAPSAR JETS

    SciTech Connect (OSTI)

    Mizuta, Akira; Ioka, Kunihito

    2013-11-10

    We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by ?{sub j} ? 1/5?{sub 0} and infer the initial Lorentz factor of the jet at the central engine, ?{sub 0}, is a few for existing observations of ?{sub j}. The jet keeps the Lorentz factor low inside the star by converging cylindrically via collimation shocks under the cocoon pressure and accelerates at jet breakout before the free expansion to a hollow-cone structure. In this new picture, the GRB duration is determined by the sound crossing time of the cocoon, after which the opening angle widens, reducing the apparent luminosity. Some bursts violating the maximum opening angle ?{sub j,{sub max}} ? 1/5 ? 12° imply the existence of a baryon-rich sheath or a long-acting jet. We can explain the slopes in both Amati and Yonetoku spectral relations using an off-centered photosphere model, if we make only one assumption that the total jet luminosity is proportional to the initial Lorentz factor of the jet. We also numerically calibrate the pre-breakout model (Bromberg et al.) for later use.

  17. 3 - 4 Turbulent combustion Princeton.key

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    speed (s T ) Turbulent RMS velocity in the fresh gas (u') Low turbulence zone s T a u' Bending zone Quenching l i m i t s L 0 Problem: these functions are configuration...

  18. Active skin for turbulent drag reduction 

    E-Print Network [OSTI]

    Mani, Raghavendran

    2002-01-01

    capitalizes on recent advances in active turbulent drag reduction and active material based actuation to develop an active or "smart" skin for turbulent drag reduction in realistic flight conditions. The skin operation principle is based on computational...

  19. Experimental studies on the group ignition of a cloud of coal particles: Volume 2, Pyrolysis and ignition modeling. Final report, August 15, 1988--October 15, 1991

    SciTech Connect (OSTI)

    Annamalai, K.; Ryan, W.

    1992-01-01

    The primary objectives of this work are to formulate a model to simulate transient coal pyrolysis, ignition, and combustion of a cloud of coal particles and to compare results of the program with those reported in the literature elsewhere.

  20. Low Frequency Architecture for Multi-Lamp CCFL Systemswith Capacitive Ignition

    E-Print Network [OSTI]

    Low Frequency Architecture for Multi-Lamp CCFL Systemswith Capacitive Ignition Monm Doshi (I-0425 regan.zane@colorado.edu Absfruci-This paper presents a low frequency architecture for driving parallel lamp ignition, and individual lamp current reguration in such designs. In this paper, we present a low

  1. Low-frequency square-wave electronic ballast with resonant ignition using digital mode and power

    E-Print Network [OSTI]

    Low-frequency square-wave electronic ballast with resonant ignition using digital mode and power both the functions of a resonant circuit for lamp ignition and a current controlled low frequency of the FB converter according to the lamp requirements. I. INTRODUCTION The primary motivation for using low

  2. Toward LES of an ignition sequence in a full helicopter combustor

    E-Print Network [OSTI]

    of Turbomeca, 18 main burners are ignited by two pilot flames. The success of an ignition attempt depends burner to generate the pilot flames. In a second step, these two flames must provide a sufficient amount of energy to initiate a stable combustion in the main burners located in their vicinity. Finally

  3. IAEA-CN-50/G-II-1 COMPACT IGNITION TOKAMAK PHYSICS AND

    E-Print Network [OSTI]

    - plasma experiments [1,2]. Burning-plasma operation in ITER and more advanced fusion reactors [3IAEA-CN-50/G-II-1 COMPACT IGNITION TOKAMAK PHYSICS AND ENGINEERING BASIS* R.R. PARKER', G. BATEMAN University, Princeton, New Jersey, United States of America Abstract COMPACT IGNITION TOKAMAK PHYSICS

  4. Ignition and Combustion of Fuel Pockets Moving in an Oxidizing Atmosphere

    E-Print Network [OSTI]

    Heil, Matthias

    velocity of the fuel kernel v velocity vector (in a frame at rest with the fluid at infinity) x coordinateIgnition and Combustion of Fuel Pockets Moving in an Oxidizing Atmosphere JOEL DAOU Dpto, Spain. E-mail: daou@tupi.dmt.upm.es Ignition and combustion of an initially spherical pocket of fuel

  5. Increased Hot-Plate Ignition Probability for Nanoparticle-Laden Diesel Fuel

    E-Print Network [OSTI]

    Pacheco, Jose Rafael

    droplets of the fuel were allowed to fall in a controlled environment on a heated metallic plateIncreased Hot-Plate Ignition Probability for Nanoparticle-Laden Diesel Fuel Himanshu Tyagi, Patrick April 2, 2008 ABSTRACT The present study attempts to improve the ignition properties of diesel fuel

  6. Ignition and Combustion of Fuel Pockets Moving in an Oxidizing Atmosphere

    E-Print Network [OSTI]

    Sidorov, Nikita

    Ignition and Combustion of Fuel Pockets Moving in an Oxidizing Atmosphere JOEL DAOU Dpto, Spain. E-mail: daou@tupi.dmt.upm.es Ignition and combustion of an initially spherical pocket of fuel, the results provide a good appreciation of the dynamics of the combustion process. For example, it is found

  7. Influence of Loss-on-Ignition Temperature and Heating Time on Ash Content

    E-Print Network [OSTI]

    Selinger, Brent

    Influence of Loss-on-Ignition Temperature and Heating Time on Ash Content of Compost and Manure-on-ignition (LOI) is a simple method for determining ash content, and by reciprocation, organic matter content, 16, 20, and 24-h) on the ash content of a finished compost and a fresh manure. The experiment

  8. Wildfire ignition resistant home design(WIRHD) program: Full-scale testing and demonstration final report.

    SciTech Connect (OSTI)

    Quarles, Stephen, L.; Sindelar, Melissa

    2011-12-13

    The primary goal of the Wildfire ignition resistant home design(WIRHD) program was to develop a home evaluation tool that could assess the ignition potential of a structure subjected to wildfire exposures. This report describes the tests that were conducted, summarizes the results, and discusses the implications of these results with regard to the vulnerabilities to homes and buildings.

  9. Mise en vidence du phnomne d'auto-ignition dans les

    E-Print Network [OSTI]

    Aubertin, Michel

    pollution et d'augmenter les réserves exploitées. En effet, l'un des avantages de l'utilisation du remblai'auto-ignition. L'auto-ignition se manifeste par une combustion interne des remblais en place suite à une déchets miniers sont celles reliées au problème d'auto-combustion de stériles sulfureux issus de l

  10. LES of an ignition sequence in a gas turbine M. Boileau a,, G. Staffelbach a

    E-Print Network [OSTI]

    LES of an ignition sequence in a gas turbine engine M. Boileau a,, G. Staffelbach a , B. CuenotTurbomeca (SAFRAN group), Bordes, France Abstract Being able to ignite or reignite a gas turbine engine in a cold including 18 burners. This geometry corresponds to a real gas turbine chamber. Massively parallel computing

  11. A comparison of various models in predicting ignition delay in single-particle coal combustion

    E-Print Network [OSTI]

    A comparison of various models in predicting ignition delay in single-particle coal combustion November 2013 Accepted 7 January 2014 Available online xxxx Keywords: Coal Devolatilization Ignition delay a b s t r a c t In this paper, individual coal particle combustion under laminar conditions

  12. Fusion Ignition Research Experiment (FIRE) Dale M. Meade

    E-Print Network [OSTI]

    several critical unresolved fusion science issues: · Turbulence and transport · Energy density limits on BPX, TPX and ITER. Advanced Energy Systems Argonne National Laboratory Bechtel Technology would cost in excess of $1 billion. Given the cost, it is not practical to construct a variety of large-scale

  13. Diffusive Radiation in One-dimensional Langmuir Turbulence

    E-Print Network [OSTI]

    Fleishman, Gregory D

    2007-01-01

    We calculate spectra of radiation produced by a relativistic particle in the presence of one-dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular, in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend sensitively on the angle between the particle velocity and electric field direction. The radiation spectrum in the case of exactly transverse particle motion is degenerate and similar to that of spatially uniform Langmuir oscillations. In case of oblique propagation, the spectrum is more complex, it consists of a number of power-law regions and may contain a distinct high-frequency spectral peak. %at $\\omega=2\\omega\\pe \\gamma^2$. The emission process considered is relevant to various laboratory plasma settings and for astrophysical objects as gamma-ray bursts and collimated jets.

  14. Diffusive Radiation in One-dimensional Langmuir Turbulence

    E-Print Network [OSTI]

    Gregory D. Fleishman; Igor N. Toptygin

    2007-05-21

    We calculate spectra of radiation produced by a relativistic particle in the presence of one-dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular, in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend sensitively on the angle between the particle velocity and electric field direction. The radiation spectrum in the case of exactly transverse particle motion is degenerate and similar to that of spatially uniform Langmuir oscillations. In case of oblique propagation, the spectrum is more complex, it consists of a number of power-law regions and may contain a distinct high-frequency spectral peak. %at $\\omega=2\\omega\\pe \\gamma^2$. The emission process considered is relevant to various laboratory plasma settings and for astrophysical objects as gamma-ray bursts and collimated jets.

  15. Effect of experimentally observed hydrogenic fractionation on inertial confinement fusion ignition target performance

    SciTech Connect (OSTI)

    McKenty, P. W.; Wittman, M. D.; Harding, D. R. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

    2006-10-01

    The need of cryogenic hydrogenic fuels in inertial confinement fusion (ICF) ignition targets has been long been established. Efficient implosion of such targets has mandated keeping the adiabat of the main fuel layer at low levels to ensure drive energies are kept at reasonable minima. The use of cryogenic fuels helps meet this requirement and has therefore become the standard in most ICF ignition designs. To date most theoretical ICF ignition target designs have assumed a homogeneous layer of deuterium-tritium (DT) fuel kept slightly below the triple point. However, recent work has indicated that, as cryogenic fuel layers are formed inside an ICF capsule, isotopic dissociation of the tritium (T), deuterium (D), and DT takes place leading to a 'fractionation' of the final ice layer. This paper will numerically investigate the effects that various scenarios of fractionation have on hot-spot formation, ignition, and burn in ICF ignition target designs.

  16. Target diagnostic system for the national ignition facility (invited)

    SciTech Connect (OSTI)

    Leeper, R.J.; Chandler, G.A.; Cooper, G.W.; Derzon, M.S.; Fehl, D.L.; Hebron, D.E.; Moats, A.R.; Noack, D.D.; Porter, J.L.; Ruggles, L.E.; Ruiz, C.L.; Torres, J.A.; Cable, M.D.; Bell, P.M.; Clower, C.A.; Hammel, B.A.; Kalantar, D.H.; Karpenko, V.P.; Kauffman, R.L.; Kilkenny, J.D.; Lee, F.D.; Lerche, R.A.; MacGowan, B.J.; Moran, M.J.; Nelson, M.B.; Olson, W.; Orzechowski, T.J.; Phillips, T.W.; Ress, D.; Tietbohl, G.L.; Trebes, J.E.; Bartlett, R.J.; Berggren, R.; Caldwell, S.E.; Chrien, R.E.; Failor, B.H.; Fernandez, J.C.; Hauer, A.; Idzorek, G.; Hockaday, R.G.; Murphy, T.J.; Oertel, J.; Watt, R.; Wilke, M.; Bradley, D.K.; Knauer, J.; Petrasso, R.D.; Li, C.K.

    1997-01-01

    A review of recent progress on the design of a diagnostic system proposed for ignition target experiments on the National Ignition Facility (NIF) will be presented. This diagnostic package contains an extensive suite of optical, x ray, gamma ray, and neutron diagnostics that enable measurements of the performance of both direct and indirect driven NIF targets. The philosophy used in designing all of the diagnostics in the set has emphasized redundant and independent measurement of fundamental physical quantities relevant to the operation of the NIF target. A unique feature of these diagnostics is that they are being designed to be capable of operating in the high radiation, electromagnetic pulse, and debris backgrounds expected on the NIF facility. The diagnostic system proposed can be categorized into three broad areas: laser characterization, hohlraum characterization, and capsule performance diagnostics. The operating principles of a representative instrument from each class of diagnostic employed in this package will be summarized and illustrated with data obtained in recent prototype diagnostic tests. {copyright} {ital 1997 American Institute of Physics.}

  17. FIREBALL: Fusion Ignition Rocket Engine with Ballistic Ablative Lithium Liner

    SciTech Connect (OSTI)

    Martin, Adam K.; Eskridge, Richard H.; Lee, Michael H. [Propulsion Research Center, NASA Marshall Space Flight Center XD22, Huntsville, AL 35812 (United States); Fimognari, Peter J. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2006-01-20

    Thermo-nuclear fusion may be the key to a high Isp, high specific power propulsion system. In a fusion system energy is liberated within, and imparted directly to, the propellant. In principle, this can overcome the performance limitations inherent in systems that require thermal power transfer across a material boundary, and/or multiple power conversion stages (NTR, NEP). A thermo-nuclear propulsion system, which attempts to overcome some of the problems inherent in the Orion concept, is described. A dense FRC plasmoid is accelerated to high velocity (in excess of 500 km/s) and is compressed into a detached liner (pulse unit). The kinetic energy of the FRC is converted into thermal and magnetic-field energy, igniting a fusion burn in the magnetically confined plasma. The fusion reaction serves as an ignition source for the liner, which is made out of detonable materials. The energy liberated in this process is converted to thrust by a pusher-plate, as in the classic Orion concept. However with this concept, the vehicle does not carry a magazine of autonomous pulse-units. By accelerating a second, heavier FRC, which acts as a piston, right behind the first one, the velocity required to initiate the fusion burn is greatly reduced.

  18. The Neutron Imaging System Fielded at the National Ignition Facility

    SciTech Connect (OSTI)

    Merrill, F E; Buckles, R; Clark, D D; Danly, C R; Drury, O B; Dzenitis, J M; Fatherley, V E; Fittinghoff, D N; Gallegos, R; Grim, G P; Guler, N; Loomis, E N; Lutz, S; Malone, R M; Martinson, D D; Mares, D; Morley, D J; Morgan, G L; Oertel, J A; Tregillis, I L; Volegov, P L; Weiss, P B; Wilde, C H

    2012-08-01

    A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of Inertial Confinement Fusion (ICF) implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

  19. Neutron source reconstruction from pinhole imaging at National Ignition Facility

    SciTech Connect (OSTI)

    Volegov, P.; Danly, C. R.; Grim, G. P.; Guler, N.; Merrill, F. E.; Wilde, C. H.; Wilson, D. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Fittinghoff, D. N.; Izumi, N.; Ma, T.; Warrick, A. L. [Livermore National Laboratory, Livermore, California 94550 (United States)] [Livermore National Laboratory, Livermore, California 94550 (United States)

    2014-02-15

    The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the ignition stage of inertial confinement fusion (ICF) implosions at NIF. Since the neutron source is small (?100 ?m) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-?m resolution are 20-cm long, single-sided tapers in gold. These apertures, which have triangular cross sections, produce distortions in the image, and the extended nature of the pinhole results in a non-stationary or spatially varying point spread function across the pinhole field of view. In this work, we have used iterative Maximum Likelihood techniques to remove the non-stationary distortions introduced by the aperture to reconstruct the underlying neutron source distributions. We present the detailed algorithms used for these reconstructions, the stopping criteria used and reconstructed sources from data collected at NIF with a discussion of the neutron imaging performance in light of other diagnostics.

  20. Ignition and extinction phenomena in helium micro hollow cathode discharges

    SciTech Connect (OSTI)

    Kulsreshath, M. K.; Schwaederle, L.; Dufour, T.; Lefaucheux, P.; Dussart, R.; Overzet, L. J.

    2013-12-28

    Micro hollow cathode discharges (MHCD) were produced using 250??m thick dielectric layer of alumina sandwiched between two nickel electrodes of 8??m thickness. A through cavity at the center of the chip was formed by laser drilling technique. MHCD with a diameter of few hundreds of micrometers allowed us to generate direct current discharges in helium at up to atmospheric pressure. A slowly varying ramped voltage generator was used to study the ignition and the extinction periods of the microdischarges. The analysis was performed by using electrical characterisation of the V-I behaviour and the measurement of He*({sup 3}S{sub 1}) metastable atoms density by tunable diode laser spectroscopy. At the ignition of the microdischarges, 2??s long current peak as high as 24?mA was observed, sometimes followed by low amplitude damped oscillations. At helium pressure above 400?Torr, an oscillatory behaviour of the discharge current was observed just before the extinction of the microdischarges. The same type of instability in the extinction period at high pressure also appeared on the density of He*({sup 3}S{sub 1}) metastable atoms, but delayed by a few ?s relative to the current oscillations. Metastable atoms thus cannot be at the origin of the generation of the observed instabilities.

  1. Characterization of in situ oil shale retorts prior to ignition

    DOE Patents [OSTI]

    Turner, Thomas F. (Laramie, WY); Moore, Dennis F. (Laramie, WY)

    1984-01-01

    Method and system for characterizing a vertical modified in situ oil shale retort prior to ignition of the retort. The retort is formed by mining a void at the bottom of a proposed retort in an oil shale deposit. The deposit is then sequentially blasted into the void to form a plurality of layers of rubble. A plurality of units each including a tracer gas cannister are installed at the upper level of each rubble layer prior to blasting to form the next layer. Each of the units includes a receiver that is responsive to a coded electromagnetic (EM) signal to release gas from the associated cannister into the rubble. Coded EM signals are transmitted to the receivers to selectively release gas from the cannisters. The released gas flows through the retort to an outlet line connected to the floor of the retort. The time of arrival of the gas at a detector unit in the outlet line relative to the time of release of gas from the cannisters is monitored. This information enables the retort to be characterized prior to ignition.

  2. The National Ignition Facility: Laser Performance and First Experiments

    SciTech Connect (OSTI)

    Wuest, C R; Moses, E I

    2004-09-09

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. NIF will be the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 108 K and 1011 bar, conditions that exist naturally only in the interior of stars, planets and in nuclear weapons. NIF has successfully activated, commissioned, and utilized the first four beams of the laser system to conduct over 300 shots between November 2002 and August 2004. NIF laser scientists have established that the laser meets nearly all performance requirements on a per beam basis for energy, uniformity, timing, and pulse shape. Using these four beams, ICF and high-energy-density physics researchers have conducted a number of experimental campaigns resulting in high quality data that could not be reached on any other laser system. We discuss the successful NIF Early Light Program including details of laser performance, examples of experiments performed to date, and recent advances in the ICF Program that enhance prospects for successful achievement of fusion ignition on NIF.

  3. Direct Injection Compression Ignition Diesel Automotive Technology Education GATE Program

    SciTech Connect (OSTI)

    Anderson, Carl L

    2006-09-25

    The underlying goal of this prqject was to provide multi-disciplinary engineering training for graduate students in the area of internal combustion engines, specifically in direct injection compression ignition engines. The program was designed to educate highly qualified engineers and scientists that will seek to overcome teclmological barriers preventing the development and production of cost-effective high-efficiency vehicles for the U.S. market. Fu1iher, these highly qualified engineers and scientists will foster an educational process to train a future workforce of automotive engineering professionals who are knowledgeable about and have experience in developing and commercializing critical advanced automotive teclmologies. Eight objectives were defmed to accomplish this goal: 1. Develop an interdisciplinary internal co1nbustion engine curriculum emphasizing direct injected combustion ignited diesel engines. 2. Encourage and promote interdisciplinary interaction of the faculty. 3. Offer a Ph.D. degree in internal combustion engines based upon an interdisciplinary cuniculum. 4. Promote strong interaction with indusuy, develop a sense of responsibility with industry and pursue a self sustaining program. 5. Establish collaborative arrangements and network universities active in internal combustion engine study. 6. Further Enhance a First Class educational facility. 7. Establish 'off-campus' M.S. and Ph.D. engine programs of study at various indusuial sites. 8. Extend and Enhance the Graduate Experience.

  4. Numerical Study of a Turbulent Hydraulic Jump

    E-Print Network [OSTI]

    Zhao, Qun

    Numerical Study of a Turbulent Hydraulic Jump Qun Zhao, Shubhra Misra, Ib. A. Svendsen and James T of a Turbulent Hydraulic Jump ­ p.1/14 #12;Objective Our ultimate goal is to study the breaking waves. Numerical Study of a Turbulent Hydraulic Jump ­ p.2/14 #12;A moving bore Qiantang Bore China (Courtesy of Dr J

  5. Advanced Concept Exploration for Fast Ignition Science Program, Final Report

    SciTech Connect (OSTI)

    Stephens, Richard Burnite [General Atomics; McLean, Harry M. [Lawrence Livermore National Laboratory; Theobald, Wolfgang [Laboratory for Laser Energetics; Akli, Kramer U. [The Ohio State University; Beg, Farhat N. [University of California, San Diego; Sentoku, Yasuhiko [University of Nevada, Reno; Schumacher, Douglass W. [The Ohio State University; Wei, Mingsheng [General Atomics

    2013-09-04

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional “central hot spot” (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10’s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The physics of fast ignition process was the focus of our Advanced Concept Exploration (ACE) program. Ignition depends critically on two major issues involving Relativistic High Energy Density (RHED) physics: The laser-induced creation of fast electrons and their propagation in high-density plasmas. Our program has developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to advance understanding of the fundamental physics underlying these issues. Our program had three thrust areas: • Understand the production and characteristics of fast electrons resulting from FI relevant laser-plasma interactions and their dependence on laser prepulse and laser pulse length. • Investigate the subsequent fast electron transport in solid and through hot (FI-relevant) plasmas. • Conduct and understand integrated core-heating experiments by comparison to simulations. Over the whole period of this project (three years for this contract), we have greatly advanced our fundamental understanding of the underlying properties in all three areas: • Comprehensive studies on fast electron source characteristics have shown that they are controlled by the laser intensity distribution and the topology and plasma density gradient. Laser pre-pulse induced pre-plasma in front of a solid surface results in increased stand-off distances from the electron origin to the high density target as well as large and erratic spread of the electron beam with increasing short pulse duration. We have demonstrated, using newly available higher contrast lasers, an improved energy coupling, painting a promising picture for FI feasibility. • Our detailed experiments and analyses of fast electron transport dependence on target material have shown that it is feasible to collimate fast electron beam by self-generated resistive magnetic fields in engineered targets with a rather simple geometry. Stable and collimated electron beam with spot size as small as 50-?m after >100-?m propagation distance (an angular divergence angle of 20°!) in solid density plasma targets has been demonstrated with FI-relevant (10-ps, >1-kJ) laser pulses Such collimated beam would meet the required heating beam size for FI. • Our new experimental platforms developed for the OMEGA laser (i.e., i) high resolution 8 keV backlighter platform for cone-in-shell implosion and ii) the 8 keV imaging with Cu-doped shell targets for detailed transport characterization) have enabled us to experimentally confirm fuel assembly from cone-in-shell implosion with record-high areal density. We have also made the first direct measurement of fast electron transport and spatial energy deposition in integrated FI experiments enabling the first experiment-based benchmarking of integrated simulation codes. Executing this program required a large team. It was managed as a collaboration between General Atomics (GA), Lawrence Livermore National Laboratory (LLNL), and the Laboratory for Laser Energetics (LLE). GA fulfills its responsibilities jointly with the University of California, San Diego (UCSD), The Ohio State University (OSU) and the University of Nevada at Reno (UNR). The division of responsibility was as follows: (1) LLE had primary leadership for channeling studies and the integrated energy transfer, (2) LLNL led the development of measurement methods, analysis, and deployment of diagnostics, and (3) GA together with UCSD, OSU and UNR studied the detailed energy-transfer physics. Th

  6. Turbulence Induced Transport in Tokamaks

    SciTech Connect (OSTI)

    Caldas, I. L.; Marcus, F. A.; Heller, M. V. A. P.; Guimaraes-Filho, Z. O. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Batista, A. M. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, Ponta Grossa, PR (Brazil); Viana, R. L.; Lopes, S. R. [Departamento de Fisica, Universidade Federal do Parana, 81531-990, Curitiba, PR (Brazil); Morrison, P. J.; Horton, W. [Department of Physics, University of Texas at Austin, Austin, Texas, 78712 (United States); Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas, 78712 (United States)

    2006-12-04

    This report is concerned with plasma edge turbulence and its relation to anomalous particle transport in tokamaks. First, experimental evidence of turbulence driven particle transport and measurements of the gradients of the equilibrium profiles in the Brazilian tokamaks TBR and TCABR are presented. Next, diffusion in a two drift-wave system is discussed. In this nonintegrable system, particle transport is associated with the onset of chaotic orbits. Finally, numerical evidence suggesting that a nonlinear three-mode interaction could contribute to the intermittent plasma fluctuations observed in tokamaks is presented.

  7. KINETIC MODELING OF A SURROGATE DIESEL FUEL APPLIED TO 3D AUTO-IGNITION IN HCCI ENGINES

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    KINETIC MODELING OF A SURROGATE DIESEL FUEL APPLIED TO 3D AUTO-IGNITION IN HCCI ENGINES R OF A SURROGATE DIESEL FUEL APPLIED TO 3D AUTO-IGNITION IN HCCI ENGINES INTRODUCTION Engines running on HCCI combustion mode (Homogeneous Charge Compression Ignition) have the potential to provide both diesel

  8. A review of the main driving factors of forest fire ignition over Europe Anne GanteaumeA,C

    E-Print Network [OSTI]

    Boyer, Edmond

    A review of the main driving factors of forest fire ignition over Europe Anne GanteaumeA,C , Andrea of forest fires, and of the main driving factors of ignition, is an indispensable step towards effective fire prevention policies. This paper analyses the factors driving forest fire ignition

  9. IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 39, NO. 12, DECEMBER 2011 3307 Microwave-Plasma-Coupled Re-Ignition of

    E-Print Network [OSTI]

    Lee, Tonghun

    , improved fuel efficiency through more complete combustion, reduction of pollution by altering oxidation by-assisted ig- nition and combustion research works. Results indicate that, for re-ignition to occur-ignition to occur. Index Terms--Auto-ignition temperature, laser induced fluores- cence, plasma assisted combustion

  10. A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation

    SciTech Connect (OSTI)

    McKinney, Jonathan C.; Uzdensky, Dmitri A.

    2012-03-14

    Prompt gamma-ray burst (GRB) emission requires some mechanism to dissipate an ultrarelativistic jet. Internal shocks or some form of electromagnetic dissipation are candidate mechanisms. Any mechanism needs to answer basic questions, such as what is the origin of variability, what radius does dissipation occur at, and how does efficient prompt emission occur. These mechanisms also need to be consistent with how ultrarelativistic jets form and stay baryon pure despite turbulence and electromagnetic reconnection near the compact object and despite stellar entrainment within the collapsar model. We use the latest magnetohydrodynamical models of ultrarelativistic jets to explore some of these questions in the context of electromagnetic dissipation due to the slow collisional and fast collisionless reconnection mechanisms, as often associated with Sweet-Parker and Petschek reconnection, respectively. For a highly magnetized ultrarelativistic jet and typical collapsar parameters, we find that significant electromagnetic dissipation may be avoided until it proceeds catastrophically near the jet photosphere at large radii (r {approx} 10{sup 13}-10{sup 14}cm), by which the jet obtains a high Lorentz factor ({gamma} {approx} 100-1000), has a luminosity of L{sub j} {approx} 10{sup 50}-10{sup 51} erg s{sup -1}, has observer variability timescales of order 1s (ranging from 0.001-10s), achieves {gamma}{theta}{sub j} {approx} 10-20 (for opening half-angle {theta}{sub j}) and so is able to produce jet breaks, and has comparable energy available for both prompt and afterglow emission. A range of model parameters are investigated and simplified scaling laws are derived. This reconnection switch mechanism allows for highly efficient conversion of electromagnetic energy into prompt emission and associates the observed prompt GRB pulse temporal structure with dissipation timescales of some number of reconnecting current sheets embedded in the jet. We hope this work helps motivate the development of self-consistent radiative compressible relativistic reconnection models.

  11. Gravitational Collapse in Turbulent Molecular Clouds. II. Magnetohydrodynamical Turbulence

    E-Print Network [OSTI]

    F. Heitsch; M. -M. Mac Low; R. S. Klessen

    2000-09-14

    Hydrodynamic supersonic turbulence can only prevent local gravitational collapse if the turbulence is driven on scales smaller than the local Jeans lengths in the densest regions, a very severe requirement (Paper I). Magnetic fields have been suggested to support molecular clouds either magnetostatically or via magnetohydrodynamic (MHD) waves. Whereas the first mechanism would form sheet-like clouds, the second mechanism not only could exert a pressure onto the gas counteracting the gravitational forces, but could lead to a transfer of turbulent kinetic energy down to smaller spatial scales via MHD wave interactions. This turbulent magnetic cascade might provide sufficient energy at small scales to halt local collapse. We test this hypothesis with MHD simulations at resolutions up to 256^3 zones, done with ZEUS-3D. We first derive a resolution criterion for self-gravitating, magnetized gas: in order to prevent collapse of magnetostatically supported regions due to numerical diffusion, the minimum Jeans length must be resolved by four zones. Resolution of MHD waves increases this requirement to roughly six zones. We then find that magnetic fields cannot prevent local collapse unless they provide magnetostatic support. Weaker magnetic fields do somewhat delay collapse and cause it to occur more uniformly across the supported region in comparison to the hydrodynamical case. However, they still cannot prevent local collapse for much longer than a global free-fall time.

  12. Turbulent mixing layers in supersonic protostellar outflows, with application to DG Tauri

    E-Print Network [OSTI]

    White, Marc C; Sutherland, Ralph S; Salmeron, Raquel; McGregor, Peter J

    2015-01-01

    Turbulent entrainment processes may play an important role in the outflows from young stellar objects at all stages of their evolution. In particular, lateral entrainment of ambient material by high-velocity, well-collimated protostellar jets may be the cause of the multiple emission-line velocity components observed in the microjet-scale outflows driven by classical T Tauri stars. Intermediate-velocity outflow components may be emitted by a turbulent, shock- excited mixing layer along the boundaries of the jet. We present a formalism for describing such a mixing layer based on Reynolds decomposition of quantities measuring fundamental properties of the gas. In this model, the molecular wind from large disc radii provides a continual supply of material for entrainment. We calculate the total stress profile in the mixing layer, which allows us to estimate the dissipation of turbulent energy, and hence the luminosity of the layer. We utilize MAPPINGS IV shock models to determine the fraction of total emission t...

  13. Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-2

    SciTech Connect (OSTI)

    Nguyen, H.L.; Wey, Mingjyh.

    1990-01-01

    Two dimensional calculations were made of spark ignited premixed-charge combustion and direct injection stratified-charge combustion in gasoline fueled piston engines. Results are obtained using kinetic-controlled combustion submodel governed by a four-step global chemical reaction or a hybrid laminar kinetics/mixing-controlled combustion submodel that accounts for laminar kinetics and turbulent mixing effects. The numerical solutions are obtained by using KIVA-2 computer code which uses a kinetic-controlled combustion submodel governed by a four-step global chemical reaction (i.e., it assumes that the mixing time is smaller than the chemistry). A hybrid laminar/mixing-controlled combustion submodel was implemented into KIVA-2. In this model, chemical species approach their thermodynamics equilibrium with a rate that is a combination of the turbulent-mixing time and the chemical-kinetics time. The combination is formed in such a way that the longer of the two times has more influence on the conversion rate and the energy release. An additional element of the model is that the laminar-flame kinetics strongly influence the early flame development following ignition.

  14. Modification of vortex dynamics and transport properties of transitional axisymmetric jets using zero-net-mass-flux actuation

    SciTech Connect (OSTI)

    Önder, Asim; Meyers, Johan

    2014-07-15

    We study the near field of a zero-net-mass-flux (ZNMF) actuated round jet using direct numerical simulations. The Reynolds number of the jet Re{sub D} = 2000 and three ZNMF actuators are used, evenly distributed over a circle, and directed towards the main jet. The actuators are triggered in phase, and have a relatively low momentum coefficient of C{sub ?} = 0.0049 each. We study four different control frequencies with Strouhal numbers ranging from St{sub D} = 0.165 to St{sub D} = 1.32; next to that, also two uncontrolled baseline cases are included in the study. We find that this type of ZNMF actuation leads to strong deformations of the near-field jet region that are very similar to those observed for non-circular jets. At the end of the jet's potential core (x/D = 5), the jet-column cross section is deformed into a hexagram-like geometry that results from strong modifications of the vortex structures. Two mechanisms lead to these modifications, i.e., (i) self-deformation of the jet's primary vortex rings started by distortions in their azimuthal curvature by the actuation, and (ii) production of side jets by the development and subsequent detachment of secondary streamwise vortex pairs. Further downstream (x/D = 10), the jet transforms into a triangular pattern, as the sharp corner regions of the hexagram entrain fluid and spread. We further investigate the global characteristics of the actuated jets. In particular when using the jet preferred frequency, i.e., St{sub D} = 0.33, parameters such as entrainment, centerline decay rate, and mean turbulent kinetic energy are significantly increased. Furthermore, high frequency actuation, i.e., St{sub D} = 1.32, is found to suppress the mechanisms leading to large scale structure growth and turbulent kinetic energy production. The simulations further include a passive scalar equation, and passive scalar mixing is also quantified and visualized.

  15. A comparison between synthetic jets and continuous jets B.L. Smith, G.W. Swift

    E-Print Network [OSTI]

    Smith, Barton L.

    A comparison between synthetic jets and continuous jets B.L. Smith, G.W. Swift Abstract Experimental measurements and flow visualiza- tion of synthetic jets and continuous jets with matched Reynolds numbers are described. Although they have the same profile shape, synthetic jets are wider and slower than

  16. Numerical Simulations for Jet-Proton Interaction

    E-Print Network [OSTI]

    McDonald, Kirk

    inside the jet. Setup of the Simulation of the Circular Jet downstream upstream #12;3 Sergei's result at the Initial Time Energy deposition at x=0 plane, the pressure unit is bar upstream downstream #12;4 Results of the Simulation of the Elliptic Jet downstream upstream #12;7 Jet surface at 0 and 140 microsecond Results from

  17. The interaction between two radial jets 

    E-Print Network [OSTI]

    Gruber, Thomas Clifton

    1993-01-01

    Arrays of impinging jets are used in industry for heat and mass transfer processes. A new type of jet was recently developed which could be utilized in such arrays. This jet is the radial jet and it offers the advantages of variable net force...

  18. Latest Jets Results from the Tevatron

    E-Print Network [OSTI]

    Christina Mesropian

    2011-06-15

    A comprehensive overview of the latest aspects of jet physics in proton-antiproton collisions at $\\sqrt{s}=$1.96 TeV is presented. In particular, measurements of the inclusive jet production, dijet and multi-jet production, and jet substructure studies are discussed.

  19. Jet energy calibration at the LHC

    E-Print Network [OSTI]

    Ariel Schwartzman

    2015-09-17

    Jets are one of the most prominent physics signatures of high energy proton proton (p-p) collisions at the Large Hadron Collider (LHC). They are key physics objects for precision measurements and searches for new phenomena. This review provides an overview of the reconstruction and calibration of jets at the LHC during its first Run. ATLAS and CMS developed different approaches for the reconstruction of jets, but use similar methods for the energy calibration. ATLAS reconstructs jets utilizing input signals from their calorimeters and use charged particle tracks to refine their energy measurement and suppress the effects of multiple p-p interactions (pileup). CMS, instead, combines calorimeter and tracking information to build jets from particle flow objects. Jets are calibrated using Monte Carlo (MC) simulations and a residual in situ calibration derived from collision data is applied to correct for the differences in jet response between data and Monte Carlo. Large samples of dijet, Z+jets, and photon+jet events at the LHC allowed the calibration of jets with high precision, leading to very small systematic uncertainties. Both ATLAS and CMS achieved a jet energy calibration uncertainty of about 1% in the central detector region and for jets with transverse momentum pT>100 GeV. At low jet pT, the jet energy calibration uncertainty is less than 4%, with dominant contributions from pileup, differences in energy scale between quark and gluon jets, and jet flavor composition.

  20. Water cooled steam jet

    DOE Patents [OSTI]

    Wagner, E.P. Jr.

    1999-01-12

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed there between. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock. 2 figs.

  1. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, S.P.

    1999-03-02

    A dispenser is disclosed for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 {micro}m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (ca. 200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments. 4 figs.

  2. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, Steve P. (Livermore, CA)

    1999-03-02

    A dispenser for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 .mu.m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (.about.200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments.

  3. Water cooled steam jet

    DOE Patents [OSTI]

    Wagner, Jr., Edward P. (Idaho Falls, ID)

    1999-01-01

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed therebetween. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock.

  4. 2015 UTSR Poster Presentations Prediction of Auto-Ignition Regimes in Turbulent Reacting Flows with Thermal Inhomogeneities

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservationBio-InspiredAtmosphericdevicesPPONeApril 30,

  5. Jets and Jet-like correlations in STAR

    E-Print Network [OSTI]

    Alice Ohlson; for the STAR Collaboration

    2012-10-08

    The propagation and modification of hard-scattered partons in the QGP can be studied using various types of jet and jet-like correlation measurements. The STAR detector with its full azimuthal and large pseudorapidity acceptance, as well as its wide transverse momentum (pT) coverage, is well-suited for these measurements. At mid-rapidity, azimuthal correlations of charged hadrons with the axis of a reconstructed trigger jet are used to study the modification of jet shapes and associated hadron yields from p+p to Au+Au. Dihadron correlations with back-to-back high-pT hadron pairs are used to investigate dijets and fragmentation biases. STAR's increased particle identification capabilities due to the Time-Of-Flight detector are utilized to investigate the differences between jet-related and bulk-related particle production. Dihadron correlations with identified trigger particles provide experimental tests of simple recombination theories. The comprehensive set of STAR jet-quenching measurements can be used to further constrain theories of parton energy loss at RHIC.

  6. CDF/PHYS/JET/CDFR/6419 Version 1.0

    E-Print Network [OSTI]

    Galtieri, Lina

    CDF/PHYS/JET/CDFR/6419 Version 1.0 June 19, 2003 Systematic Uncertainties Associated with Jet. Schmitt Jet Corrections Group Abstract We present an estimate of the systematic uncertainties on the jet jets, as well as for raw jets are given. 1 Introduction In order to convert the jet E T measured

  7. A simplified model of TiH1.65/KClO4 pyrotechnic ignition.

    SciTech Connect (OSTI)

    Chen, Ken Shuang

    2009-04-01

    A simplified model was developed and is presented in this report for simulating thermal transport coupled with chemical reactions that lead to the pyrotechnic ignition of TiH1.65/KClO4 powder. The model takes into account Joule heating via a bridgewire, thermal contact resistance at the wire/powder interface, convective heat loss to the surroundings, and heat released from the TiH1.65- and KClO4-decomposition and TiO2-oxidation reactions. Chemical kinetic sub-models were put forth to describe the chemical reaction rate(s) and quantify the resultant heat release. The simplified model predicts pyrotechnic ignition when heat from the pyrotechnic reactions is accounted for. Effects of six key parameters on ignition were examined. It was found that the two reaction-rate parameters and the thermal contact resistance significantly affect the dynamic ignition process whereas the convective heat transfer coefficient essentially has no effect on the ignition time. Effects of the initial/ambient temperature and electrical current load through the wire are as expected. Ignition time increases as the initial/ambient temperature is lowered or the wire current load is reduced. Lastly, critical needs such as experiments to determine reaction-rate and other model-input parameters and to measure temperature profiles, time to ignition and burn-rate data for model validation as well as efforts in incorporating reaction-rate dependency on pressure are pointed out.

  8. Final Scientific and Technical Report - Practical Fiber Delivered Laser Ignition Systems for Vehicles

    SciTech Connect (OSTI)

    Yalin, Azer

    2014-03-30

    Research has characterized advanced kagome fiber optics for their use in laser ignition systems. In comparison to past fibers used in laser ignition, these fibers have the important advantage of being relatively bend-insensitivity, so that they can be bent and coiled without degradation of output energy or beam quality. The results are very promising for practical systems. For pulse durations of ~12 ns, the fibers could deliver >~10 mJ pulses before damage onset. A study of pulse duration showed that by using longer pulse duration (~20 – 30 ns), it is possible to carry even higher pulse energy (by factor of ~2-3) which also provides future opportunities to implement longer duration sources. Beam quality measurements showed nearly single-mode output from the kagome fibers (i.e. M2 close to 1) which is the optimum possible value and, combined with their high pulse energy, shows the suitability of the fibers for laser ignition. Research has also demonstrated laser ignition of an engine including reliable (100%) ignition of a single-cylinder gasoline engine using the laser ignition system with bent and coiled kagome fiber. The COV of IMEP was <2% which is favorable for stable engine operation. These research results, along with the continued reduction in cost of laser sources, support our commercial development of practical laser ignition systems.

  9. HYDROGEN IGNITION MECHANISM FOR EXPLOSIONS IN NUCLEAR FACILITY PIPE SYSTEMS

    SciTech Connect (OSTI)

    Leishear, R

    2010-05-02

    Hydrogen and oxygen generation due to the radiolysis of water is a recognized hazard in pipe systems used in the nuclear industry, where the accumulation of hydrogen and oxygen at high points in the pipe system is expected, and explosive conditions exist. Pipe ruptures at nuclear facilities were attributed to hydrogen explosions inside pipelines, in nuclear facilities, i.e., Hamaoka, Nuclear Power Station in Japan, and Brunsbuettel in Germany. Prior to these accidents an ignition source for hydrogen was questionable, but these accidents, demonstrated that a mechanism was, in fact, available to initiate combustion and explosion. Hydrogen explosions may occur simultaneously with water hammer accidents in nuclear facilities, and a theoretical mechanism to relate water hammer to hydrogen deflagrations and explosions is presented herein.

  10. Shock-ignition relevant experiments with planar targets on OMEGA

    SciTech Connect (OSTI)

    Hohenberger, M.; Hu, S. X.; Anderson, K. S.; Boehly, T. R.; Sangster, T. C.; Seka, W.; Stoeckl, C.; Yaakobi, B.; Theobald, W.; Lafon, M.; Nora, R.; Fusion Science Center, University of Rochester, Rochester, New York 14623 ; Betti, R.; Meyerhofer, D. D.; Fusion Science Center, University of Rochester, Rochester, New York 14623; Departments of Mechanical Engineering and Physics, University of Rochester, Rochester, New York 14627 ; Casner, A.; Fratanduono, D. E.; Ribeyre, X.; Schurtz, G.

    2014-02-15

    We report on laser-driven, strong-shock generation and hot-electron production in planar targets in the presence of a pre-plasma at shock-ignition (SI) relevant laser and pre-plasma conditions. 2-D simulations reproduce the shock dynamics well, indicating ablator shocks of up to 75 Mbar have been generated. We observe hot-electron temperatures of ?70?keV at intensities of 1.4?×?10{sup 15}?W/cm{sup 2} with multiple overlapping beams driving the two-plasmon decay instability. When extrapolated to SI-relevant intensities of ?10{sup 16}?W/cm{sup 2}, the hot electron temperature will likely exceed 100?keV, suggesting that tightly focused beams without overlap are better suited for launching the ignitor shock.

  11. Pathway to a lower cost high repetition rate ignition facility

    SciTech Connect (OSTI)

    Obenschain, S.P.; Colombant, D.G.; Schmitt, A.J.; Sethian, J.D.; McGeoch, M. W. [Plasma Physics Division, U.S. Naval Research Laboratory, Washington, D.C. 20375 (United States); Plex LLC, Brookline, Massachusetts 02446-5478 (United States)

    2006-05-15

    An approach to a high-repetition ignition facility based on direct drive with the krypton-fluoride laser is presented. The objective is development of a 'Fusion Test Facility' that has sufficient fusion power to be useful as a development test bed for power plant materials and components. Calculations with modern pellet designs indicate that laser energies well below a megajoule may be sufficient. A smaller driver would result in an overall smaller, less complex and lower cost facility. While this facility might appear to have most direct utility to inertial fusion energy, the high flux of neutrons would also be able to address important issues concerning materials and components for other approaches to fusion energy. The physics and technological basis for the Fusion Test Facility are presented along with a discussion of its applications.

  12. Fragmentation inside an identified jet

    E-Print Network [OSTI]

    Procura, Massimiliano

    Using Soft?Collinear Effective Theory (SCET) we derive factorization formulae for semi?inclusive processes where a light hadron h fragments from a jet whose invariant mass is measured. Our analysis yields a novel “fragmenting ...

  13. Radial flow pulse jet mixer

    DOE Patents [OSTI]

    VanOsdol, John G.

    2013-06-25

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  14. Jet production at hadron colliders

    E-Print Network [OSTI]

    Jouttenus, Teppo T. (Teppo Tapani)

    2012-01-01

    Hadronic jets feature in many final states of interest in modern collider experiments. They form a significant Standard Model background for many proposed new physics processes and also probe QCD interactions at several ...

  15. Fragmentation inside an identified jet

    SciTech Connect (OSTI)

    Procura, Massimiliano; Stewart, Iain W.

    2011-05-23

    Using Soft-Collinear Effective Theory (SCET) we derive factorization formulae for semi-inclusive processes where a light hadron h fragments from a jet whose invariant mass is measured. Our analysis yields a novel 'fragmenting jet function' G{sub i}{sup h}(s,z) that depends on the jet invariant mass {radical}(s), and on the fraction z of the large light-cone momentum components of the hadron and the parent parton i. We show that G{sub i}{sup h}(s,z) can be computed in terms of perturbatively calculable coefficients, J{sub ij}(s,z/x), integrated against standard non-perturbative fragmentation functions, D{sub j}{sup h}(x). Our analysis yields a simple replacement rule that allows any factorization theorem depending on a jet function J{sub i} to be converted to a semi-inclusive process with a fragmenting hadron h.

  16. Polar-direct-drive experiments on the National Ignition Facility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hohenberger, M.; Radha, P. B.; Myatt, J. F.; LePape, S.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; et al

    2015-05-11

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beammore »geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D? gas were imploded with total drive energies ranging from ~500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 10¹? to 1.2 10¹?W/cm². Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.« less

  17. Polar-direct-drive experiments on the National Ignition Facility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hohenberger, M. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)] (ORCID:0000000258879711); Radha, P. B. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Myatt, J. F. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); LePape, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Marozas, J. A. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Marshall, F. J. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Michel, D. T. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)] (ORCID:0000000166894359); Regan, S. P. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Seka, W. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Shvydky, A. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Sangster, T. C. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)] (ORCID:0000000340402672); Bates, J. W. [U. S. Naval Research Lab., Washington, DC (United States)] (ORCID:0000000188087240); Betti, R. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Boehly, T. R. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Bonino, M. J. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Casey, D. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Collins, T. J. B. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Craxton, R. S. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)] (ORCID:0000000158858227); Delettrez, J. A. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Edgell, D. H. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Epstein, R. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)] (ORCID:0000000340628444); Fiksel, G. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Fitzsimmons, P. [General Atomics, San Diego, CA (United States); Frenje, J. A. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)] (ORCID:0000000168460378); Froula, D. H. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Goncharov, V. N. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Harding, D. R. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Kalantar, D. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Karasik, M. [U. S. Naval Research Lab., Washington, DC (United States); Kessler, T. J. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Kilkenny, J. D. [General Atomics, San Diego, CA (United States); Knauer, J. P. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Kurz, C. [General Atomics, San Diego, CA (United States); Lafon, M. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); LaFortune, K. N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); MacGowan, B. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mackinnon, A. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); MacPhee, A. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)] (ORCID:0000000341604479); McCrory, R. L. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); McKenty, P. W. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); Meeker, J. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Meyerhofer, D. D. [Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)

    2015-05-01

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D? gas were imploded with total drive energies ranging from ~500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 10¹? to 1.2 10¹?W/cm². Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.

  18. Polar-direct-drive experiments on the national ignition facilitya)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hohenberger, M.; Radha,, P. B.; Myatt, J. F.; LePape, S.; Marozas,, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; et al

    2015-05-01

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beammore »geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D? gas were imploded with total drive energies ranging from ~500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 x 10¹? to 1.2 x 10¹?W/cm². Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.« less

  19. Aeroacoustics of volcanic jets: Acoustic power estimation and jet velocity dependence

    E-Print Network [OSTI]

    Matoza, Robin S; Fee, D; Neilsen, Tracianne B; Gee, Kent L; Ogden, Darcy E

    2013-01-01

    of noise from a military jet aircraft during ground run-up,Radiated by Subsonic Air Jets, David W. Taylor Model Basin,analysis of model-scale jet noise, J. Acoust. Soc. Am. ,

  20. Aeroacoustics of volcanic jets: Acoustic power estimation and jet velocity dependence

    E-Print Network [OSTI]

    Matoza, Robin S; Fee, D; Neilsen, Tracianne B; Gee, Kent L; Ogden, Darcy E

    2013-01-01

    e.g. , the exhaust from jet engines and rockets) [Kundu andow) issuing out of the jet engine or rocket. Other sourcesSupersonic jet noise characteristics and propagation: Engine

  1. Jet Quenching with Parton evolution

    E-Print Network [OSTI]

    Luan Cheng; Enke Wang

    2009-10-08

    We report the evolution effects on jet energy loss with detailed balance. The initial conditions and parton evolution based on perturbative QCD in the chemical non-equilibrated medium and Bjorken expanding medium at RHIC are determined. The parton evolution affect the jet energy loss evidently. This will increase the energy and propagating distance dependence of the parton energy loss and will affect the shape of suppression of moderately high P_{T} hadron spectra.

  2. Elliptical magnetic mirror generated via resistivity gradients for fast ignition inertial confinement fusion

    SciTech Connect (OSTI)

    Robinson, A. P. L.; Schmitz, H. [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom)] [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom)

    2013-06-15

    The elliptical magnetic mirror scheme for guiding fast electrons for Fast Ignition proposed by Schmitz et al. (Plasma Phys. Controlled Fusion 54, 085016 (2012)) is studied for conditions on the multi-kJ scale which are much closer to full-scale Fast Ignition. When scaled up, the elliptical mirror scheme is still highly beneficial to Fast Ignition. An increase in the coupling efficiency by a factor of 3–4 is found over a wide range of fast electron divergence half-angles.

  3. A low cost igniter utilizing an SCB and titanium sub-hydride potassium perchlorate pyrotechnic

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.; Grubelich, M.C.; Hartman, J.K.; McCampbell, C.B.; Churchill, J.K.

    1993-12-31

    A conventional NSI (NASA standard initiator) normally employs a hot-wire ignition element to ignite ZPP (zirconium potassium perchlorate). With minor modifications to the interior of a header similar to an NSI device to accommodate an SCB (semiconductor bridge), a low cost initiator was obtained. In addition, the ZPP was replaced with THKP (titanium subhydride potassium perchlorate) to obtain increased overall gas production and reduced static-charge sensitivity. This paper reports on the all-fire and no-fire levels obtained and on a dual mix device that uses THKP as the igniter mix and a thermite as the output mix.

  4. THE ODTX SYSTEM FOR THERMAL IGNITION AND THERMAL SAFETY STUDY OF ENERGETIC MATERIALS

    SciTech Connect (OSTI)

    Hsu, P C; Hust, G; Howard, M; Maienschein, J L

    2010-03-03

    Understanding the response of energetic material to thermal event is very important for the storage and handling of energetic materials. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) can precisely measure times to explosion and minimum ignition temperatures of energetic materials at elevated temperatures. These measurements provide insight into the relative ease of thermal ignition and allow for the determination of kinetic parameters. The ODTX system can potentialy be a good tool to measure violence of the thermal ignition by monitoring the size of anvil cavity. Recent ODTX experimental data on various energetic materials (solid and liquids) are reported in this paper.

  5. Twenty times lower ignition threshold for laser driven fusion using collective effects and the inhibition factor

    SciTech Connect (OSTI)

    Hora, H. [Department of Theoretical Physics, University of New South Wales, Sydney 2052 (Australia); Malekynia, B.; Ghoranneviss, M. [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran-Poonak 14835-159 (Iran, Islamic Republic of); Miley, G. H. [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois, Urbana, Illinois 61801 (United States); He, X. [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2008-07-07

    Hydrodynamic analysis for ignition of inertial fusion by Chu [Phys. Fluids 15, 413 (1972)] arrived at extremely high thresholds of a minimum energy flux density E* at 4x10{sup 8} J/cm{sup 2} which could be provided, e.g., by spark ignition. In view of alternative schemes of fast ignition, a re-evaluation of the early analysis including later discovered collective stopping power and the inhibition factor results in a 20 times lowering of the threshold for E*.

  6. Anisotropic characteristics of the Kraichnan direct cascade in two-dimensional hydrodynamic turbulence

    E-Print Network [OSTI]

    Kuznetsov, E A

    2015-01-01

    Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets introduce an essential influence in turbulence leading to strong angular dependencies for correlation functions. The energy distribution as a function of modulus $k$ for each angle in the inertial interval has the Kraichnan behavior, $\\sim k^{-4}$, and simultaneously a strong dependence on angles. However, angle average provides with a high accuracy the Kraichnan turbulence spectrum $E_k=C_K\\eta^{2/3} k^{-3}$ where $\\eta$ is enstrophy flux and the Kraichnan constant $C_K\\simeq 1.3$, in correspondence with the previous simulations. Familiar situation takes place for third-order velocity structure function $S_3^L$ which, as for the isotropic turbulence, gives the same scaling with respect to separa...

  7. Anisotropic characteristics of the Kraichnan direct cascade in two-dimensional hydrodynamic turbulence

    E-Print Network [OSTI]

    E. A. Kuznetsov; E. V. Sereshchenko

    2015-10-30

    Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets introduce an essential influence in turbulence leading to strong angular dependencies for correlation functions. The energy distribution as a function of modulus $k$ for each angle in the inertial interval has the Kraichnan behavior, $\\sim k^{-4}$, and simultaneously a strong dependence on angles. However, angle average provides with a high accuracy the Kraichnan turbulence spectrum $E_k=C_K\\eta^{2/3} k^{-3}$ where $\\eta$ is enstrophy flux and the Kraichnan constant $C_K\\simeq 1.3$, in correspondence with the previous simulations. Familiar situation takes place for third-order velocity structure function $S_3^L$ which, as for the isotropic turbulence, gives the same scaling with respect to separation length $R$ and $\\eta$, $S_3^L=C_3\\eta R^3$, but the mean over angles and time $\\bar {C_3}$ differs from its isotropic value.

  8. Highly turbulent counterflow flames: A laboratory scale benchmark for practical systems

    SciTech Connect (OSTI)

    Coppola, Gianfilippo; Coriton, Bruno; Gomez, Alessandro

    2009-09-15

    We propose a highly turbulent counterflow flame as a very useful benchmark of complexity intermediate between laminar flames and practical systems. By operating in a turbulent Reynolds number regime of relevance to practical systems such as gas turbines and internal combustion engines, it retains the interaction of turbulence and chemistry of such environments, but offers several advantages including: (a) the achievement of high Reynolds numbers without pilot flames, which is particularly advantageous from a modeling standpoint; (b) control of the transition from stable flames to local extinction/reignition conditions; (c) compactness of the domain by comparison with jet flames, with obvious advantages from both a diagnostic and, especially, a computational viewpoint; and (d) the reduction or, altogether, elimination of soot formation, thanks to the high strain rates and low residence times of such a system, and the establishment of conditions of large stoichiometric mixture fraction, as required for robust flame stabilization. We demonstrate the phenomenology of such highly strained turbulent flames under conditions spanning unpremixed, partially premixed and premixed regimes. The system lends itself to the validation of DNS and other computational models. It is also well-suited for the examination of practical fuel blends - a need that is becoming more and more pressing in view of the anticipated diversification of the future fossil fuel supply. (author)

  9. Convectively generated zonal jets by thunderstorms on Jupiter

    E-Print Network [OSTI]

    Zhang, Xi Arthur; Showman, Adam

    2011-01-01

    formation of equatorial jets in freely decaying shallowof moist convection with zonal jets on Jupiter and Saturn,Generation of equatorial jets by large-scale latent heating

  10. Numerical simulations of volcanic jets: Importance of vent overpressure

    E-Print Network [OSTI]

    Ogden, Darcy E.; Wohletz, Kenneth H.; Glatzmaier, Gary A.; Brodsky, Emily E.

    2008-01-01

    Laboratory studies of volcanic jets, J. Geophys. Res. , 89(Analysis of supersonic air jets, Phys. Rev. , 76(5), 662 –and dynamics of supersonic jets, Astron. Astrophys. , 113(

  11. JETS OF NUCLEAR MATTER FROM HIGH ENERGY HEAVY ION COLLISIONS

    E-Print Network [OSTI]

    Stocker, H.

    2013-01-01

    of California. LBL-11774 Jets of Nuclear Matter from Highclusters. Strongly correlated jets of nuclear matter areExperimental analysis of the jet phenomena is in progress.

  12. PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS (Journal...

    Office of Scientific and Technical Information (OSTI)

    PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS Citation Details In-Document Search Title: PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS A protostellar jet and outflow...

  13. Coupled Mesoscale-Large-Eddy Modeling of Realistic Stable Boundary Layer Turbulence

    E-Print Network [OSTI]

    Wang, Yao; Manuel, Lance

    2013-01-01

    Site-specific flow and turbulence information are needed for various practical applications, ranging from aerodynamic/aeroelastic modeling for wind turbine design to optical diffraction calculations. Even though highly desirable, collecting on-site meteorological measurements can be an expensive, time-consuming, and sometimes a challenging task. In this work, we propose a coupled mesoscale-large-eddy modeling framework to synthetically generate site-specific flow and turbulence data. The workhorses behind our framework are a state-of-the-art, open-source atmospheric model called the Weather Research and Forecasting (WRF) model and a tuning-free large-eddy simulation (LES) model. Using this coupled framework, we simulate a nighttime stable boundary layer (SBL) case from the well-known CASES-99 field campaign. One of the unique aspects of this work is the usage of a diverse range of observations for characterization and validation. The coupled models reproduce certain characteristics of observed low-level jets....

  14. Stopping Cooling Flows with Jets

    E-Print Network [OSTI]

    Fabrizio Brighenti; William G. Mathews

    2006-01-24

    We describe 2D gasdynamical models of jets that carry mass as well as energy to the hot gas in galaxy clusters. These flows have many attractive attributes for solving the galaxy cluster cooling flow problem: Why the hot gas temperature and density profiles resemble cooling flows but show no spectral evidence of cooling to low temperatures. Using an approximate model for the cluster A1795, we show that mass-carrying jets can reduce the overall cooling rate to or below the low values implied by X-ray spectra. Biconical subrelativistic jets, described with several ad hoc parameters, are assumed to be activated when gas flows toward or cools near a central supermassive black hole. As the jets proceed out from the center they entrain more and more ambient gas. The jets lose internal pressure by expansion and are compressed by the ambient cluster gas, becoming rather difficult to observe. For a wide variety of initial jet parameters and several feedback scenarios the global cooling can be suppressed for many Gyrs while maintaining cluster temperature profiles similar to those observed. The intermittancy of the feedback generates multiple generations of X-ray cavities similar to those observed in the Perseus Cluster and elsewhere.

  15. Numerical Simulations of Bouncing Jets

    E-Print Network [OSTI]

    Bonito, Andrea; Lee, Sanghyun

    2015-01-01

    Bouncing jets are fascinating phenomenons occurring under certain conditions when a jet impinges on a free surface. This effect is observed when the fluid is Newtonian and the jet falls in a bath undergoing a solid motion. It occurs also for non-Newtonian fluids when the jets falls in a vessel at rest containing the same fluid. We investigate numerically the impact of the experimental setting and the rheological properties of the fluid on the onset of the bouncing phenomenon. Our investigations show that the occurrence of a thin lubricating layer of air separating the jet and the rest of the liquid is a key factor for the bouncing of the jet to happen. The numerical technique that is used consists of a projection method for the Navier-Stokes system coupled with a level set formulation for the representation of the interface. The space approximation is done with adaptive finite elements. Adaptive refinement is shown to be very important to capture the thin layer of air that is responsible for the bouncing.

  16. Piloted methane/air jet flames : transport effects and aspects of scalar structure.

    SciTech Connect (OSTI)

    Karpetis, Adionos N. (Texas A& M University, College Station, TX); Chen, J. Y. (University of California, Berkeley, CA); Barlow, Robert S.; Frank, Jonathan H.

    2005-02-01

    Previously unpublished results from multiscalar point measurements in the series of piloted CH{sub 4}/air jet flames [R.S. Barlow, J.H. Frank, Proc. Combust. Inst. 27 (1998) 1087-1095] are presented and analyzed. The emphasis is on features of the data that reveal the relative importance of molecular diffusion and turbulent transport in these flames. The complete series A-F is considered. This includes laminar, transitional, and turbulent flames spanning a range in Reynolds number from 1100 to 44,800. Results on conditional means of species mass fractions, the differential diffusion parameter, and the state of the water-gas shift reaction all show that there is an evolution in these flames from a scalar structure dominated by molecular diffusion to one dominated by turbulent transport. Long records of 6000 single-point samples at each of several selected locations in flame D are used to quantify the cross-stream (radial) dependence of conditional statistics of measured scalars. The cross-stream dependence of the conditional scalar dissipation is determined from 6000-shot, line-imaging measurements at selected locations. The cross-stream dependence of reactive scalars, which is most significant in the near field of the jet flame, is attributed to radial differences in both convective and local time scales of the flow. Results illustrate some potential limitations of common modeling assumptions when applied to laboratory-scale flames and, thus, provide a more complete context for interpretation of comparisons between experiments and model calculations.

  17. Piloted methane/air jet flames: Transport effects and aspects of scalar structure

    SciTech Connect (OSTI)

    Barlow, R.S.; Frank, J.H. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States); Karpetis, A.N. [Department of Aerospace Engineering, Texas A and M University, College Station, TX 778453-3141 (United States); Chen, J.-Y. [Mechanical Engineering Department, University of California, Berkeley, CA 94720 (United States)

    2005-12-01

    Previously unpublished results from multiscalar point measurements in the series of piloted CH{sub 4}/air jet flames [R.S. Barlow, J.H. Frank, Proc. Combust. Inst. 27 (1998) 1087-1095] are presented and analyzed. The emphasis is on features of the data that reveal the relative importance of molecular diffusion and turbulent transport in these flames. The complete series A-F is considered. This includes laminar, transitional, and turbulent flames spanning a range in Reynolds number from 1100 to 44,800. Results on conditional means of species mass fractions, the differential diffusion parameter, and the state of the water-gas shift reaction all show that there is an evolution in these flames from a scalar structure dominated by molecular diffusion to one dominated by turbulent transport. Long records of 6000 single-point samples at each of several selected locations in flame D are used to quantify the cross-stream (radial) dependence of conditional statistics of measured scalars. The cross-stream dependence of the conditional scalar dissipation is determined from 6000-shot, line-imaging measurements at selected locations. The cross-stream dependence of reactive scalars, which is most significant in the near field of the jet flame, is attributed to radial differences in both convective and local time scales of the flow. Results illustrate some potential limitations of common modeling assumptions when applied to laboratory-scale flames and, thus, provide a more complete context for interpretation of comparisons between experiments and model calculations.

  18. Turbulent equipartitions in two dimensional drift convection

    SciTech Connect (OSTI)

    Isichenko, M.B.; Yankov, V.V.

    1995-07-25

    Unlike the thermodynamic equipartition of energy in conservative systems, turbulent equipartitions (TEP) describe strongly non-equilibrium systems such as turbulent plasmas. In turbulent systems, energy is no longer a good invariant, but one can utilize the conservation of other quantities, such as adiabatic invariants, frozen-in magnetic flux, entropy, or combination thereof, in order to derive new, turbulent quasi-equilibria. These TEP equilibria assume various forms, but in general they sustain spatially inhomogeneous distributions of the usual thermodynamic quantities such as density or temperature. This mechanism explains the effects of particle and energy pinch in tokamaks. The analysis of the relaxed states caused by turbulent mixing is based on the existence of Lagrangian invariants (quantities constant along fluid-particle or other orbits). A turbulent equipartition corresponds to the spatially uniform distribution of relevant Lagrangian invariants. The existence of such turbulent equilibria is demonstrated in the simple model of two dimensional electrostatically turbulent plasma in an inhomogeneous magnetic field. The turbulence is prescribed, and the turbulent transport is assumed to be much stronger than the classical collisional transport. The simplicity of the model makes it possible to derive the equations describing the relaxation to the TEP state in several limits.

  19. Active control for turbulent premixed flame simulations

    SciTech Connect (OSTI)

    Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Lijewski, Michael J.

    2004-03-26

    Many turbulent premixed flames of practical interest are statistically stationary. They occur in combustors that have anchoring mechanisms to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity that is prohibitive for detailed computational studies of turbulent flame dynamics. As a result, typical detailed simulations are performed in simplified model configurations such as decaying isotropic turbulence or inflowing turbulence. In these configurations, the turbulence seen by the flame either decays or, in the latter case, increases as the flame accelerates toward the turbulent inflow. This limits the duration of the eddy evolutions experienced by the flame at a given level of turbulent intensity, so that statistically valid observations cannot be made. In this paper, we apply a feedback control to computationally stabilize an otherwise unstable turbulent premixed flame in two dimensions. For the simulations, we specify turbulent in flow conditions and dynamically adjust the integrated fueling rate to control the mean location of the flame in the domain. We outline the numerical procedure, and illustrate the behavior of the control algorithm. We use the simulations to study the propagation and the local chemical variability of turbulent flame chemistry.

  20. Development of High Efficiency Clean Combustion Engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines

    SciTech Connect (OSTI)

    Marriott, Craig; Gonzalez, Manual; Russell, Durrett

    2011-06-30

    This report summarizes activities related to the revised STATEMENT OF PROJECT OBJECTIVES (SOPO) dated June 2010 for the Development of High-Efficiency Clean Combustion engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines (COOPERATIVE AGREEMENT NUMBER DE-FC26-05NT42415) project. In both the spark- (SI) and compression-ignition (CI) development activities covered in this program, the goal was to develop potential production-viable internal combustion engine system technologies that both reduce fuel consumption and simultaneously met exhaust emission targets. To be production-viable, engine technologies were also evaluated to determine if they would meet customer expectations of refinement in terms of noise, vibration, performance, driveability, etc. in addition to having an attractive business case and value. Prior to this activity, only proprietary theoretical / laboratory knowledge existed on the combustion technologies explored The research reported here expands and develops this knowledge to determine series-production viability. Significant SI and CI engine development occurred during this program within General Motors, LLC over more than five years. In the SI program, several engines were designed and developed that used both a relatively simple multi-lift valve train system and a Fully Flexible Valve Actuation (FFVA) system to enable a Homogeneous Charge Compression Ignition (HCCI) combustion process. Many technical challenges, which were unknown at the start of this program, were identified and systematically resolved through analysis, test and development. This report documents the challenges and solutions for each SOPO deliverable. As a result of the project activities, the production viability of the developed clean combustion technologies has been determined. At this time, HCCI combustion for SI engines is not considered production-viable for several reasons. HCCI combustion is excessively sensitive to control variables such as internal dilution level and charge temperature. As a result, HCCI combustion has limited robustness when variables exceed the required narrow ranges determined in this program. HCCI combustion is also not available for the entire range of production engine speeds and loads, (i.e., the dynamic range is limited). Thus, regular SI combustion must be employed for a majority of the full dynamic range of the engine. This degrades the potential fuel economy impact of HCCI combustion. Currently-available combustion control actuators for the simple valve train system engine do not have the authority for continuous air - fuel or torque control for managing the combustion mode transitions between SI and HCCI and thus, require further refinement to meet customer refinement expectations. HCCI combustion control sensors require further development to enable robust long-term HCCI combustion control. Finally, the added technologies required to effectively manage HCCI combustion such as electric cam phasers, central direct fuel injection, cylinder pressure sensing, high-flow exhaust gas recirculation system, etc. add excessive on-engine cost and complexity that erodes the production-viability business