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Title: Quantification of sauter mean diameter in diesel sprays using scattering-absorption extinction measurements

Abstract

Quantitative measurements of the primary breakup process in diesel sprays are lacking due to a range of experimental and diagnostic challenges, including: high droplet number density environments, very small characteristic drop size scales (~1-10 μm), and high characteristic velocities in the primary breakup region (~600 m/s). Due to these challenges, existing measurement techniques have failed to resolve a sufficient range of the temporal and spatial scales involved and much remains unknown about the primary atomization process in practical diesel sprays. To gain a better insight into this process, we have developed a joint visible and x-ray extinction measurement technique to quantify axial and radial distributions of the path-integrated Sauter Mean Diameter (SMD) and Liquid Volume Fraction (LVF) for diesel-like sprays. This technique enables measurement of the SMD in regions of moderate droplet number density, enabling construction of the temporal history of drop size development within practical diesel sprays. The experimental campaign was conducted jointly at the Georgia Institute of Technology and Argonne National Laboratory using the Engine Combustion Network “Spray D” injector. X-ray radiography liquid absorption measurements, conducted at the Advanced Photon Source at Argonne, quantify the liquid-fuel mass and volume distribution in the spray. Diffused back-illumination liquid scattering measurementsmore » were conducted at Georgia Tech to quantify the optical thickness throughout the spray. By application of Mie-scatter equations, the ratio of the absorption and scattering extinction measurements is demonstrated to yield solutions for the SMD. This work introduces the newly developed scattering-absorption measurement technique and highlights the important considerations that must be taken into account when jointly processing these measurements to extract the SMD. These considerations include co-alignment of measurements taken at different institutions, identification of viable regions where the measurement ratio can be accurately interpreted, and uncertainty analysis in the measurement ratio and resulting SMD. Because the measurement technique provides the spatial history of the SMD development, it is expected to be especially informative to the diesel spray modeling community. Results from this work will aid in understanding the effect of ambient densities and injection pressures on primary breakup and help assess the appropriateness of spray submodels for engine computational fluid dynamics codes.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Georgia Tech Research Corp.
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
OSTI Identifier:
1373298
Report Number(s):
DOE-GATECH-0007333
DOE Contract Number:
EE0007333
Resource Type:
Conference
Resource Relation:
Conference: 29th Annual Conference of the Institute for Liquid Atomization and Spraying Systems (ILASS)-Americas Conference, Atlanta, GA, May 2017
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS

Citation Formats

Martinez, Gabrielle L, Magnotti, Gina M, Knox, Benjamin W, Genzale, Caroline L, Matusik, Katarzyna E, Duke, Daniel J, Powell, Christopher F, and Kastengren, Alan L. Quantification of sauter mean diameter in diesel sprays using scattering-absorption extinction measurements. United States: N. p., 2017. Web.
Martinez, Gabrielle L, Magnotti, Gina M, Knox, Benjamin W, Genzale, Caroline L, Matusik, Katarzyna E, Duke, Daniel J, Powell, Christopher F, & Kastengren, Alan L. Quantification of sauter mean diameter in diesel sprays using scattering-absorption extinction measurements. United States.
Martinez, Gabrielle L, Magnotti, Gina M, Knox, Benjamin W, Genzale, Caroline L, Matusik, Katarzyna E, Duke, Daniel J, Powell, Christopher F, and Kastengren, Alan L. Thu . "Quantification of sauter mean diameter in diesel sprays using scattering-absorption extinction measurements". United States. doi:. https://www.osti.gov/servlets/purl/1373298.
@article{osti_1373298,
title = {Quantification of sauter mean diameter in diesel sprays using scattering-absorption extinction measurements},
author = {Martinez, Gabrielle L and Magnotti, Gina M and Knox, Benjamin W and Genzale, Caroline L and Matusik, Katarzyna E and Duke, Daniel J and Powell, Christopher F and Kastengren, Alan L},
abstractNote = {Quantitative measurements of the primary breakup process in diesel sprays are lacking due to a range of experimental and diagnostic challenges, including: high droplet number density environments, very small characteristic drop size scales (~1-10 μm), and high characteristic velocities in the primary breakup region (~600 m/s). Due to these challenges, existing measurement techniques have failed to resolve a sufficient range of the temporal and spatial scales involved and much remains unknown about the primary atomization process in practical diesel sprays. To gain a better insight into this process, we have developed a joint visible and x-ray extinction measurement technique to quantify axial and radial distributions of the path-integrated Sauter Mean Diameter (SMD) and Liquid Volume Fraction (LVF) for diesel-like sprays. This technique enables measurement of the SMD in regions of moderate droplet number density, enabling construction of the temporal history of drop size development within practical diesel sprays. The experimental campaign was conducted jointly at the Georgia Institute of Technology and Argonne National Laboratory using the Engine Combustion Network “Spray D” injector. X-ray radiography liquid absorption measurements, conducted at the Advanced Photon Source at Argonne, quantify the liquid-fuel mass and volume distribution in the spray. Diffused back-illumination liquid scattering measurements were conducted at Georgia Tech to quantify the optical thickness throughout the spray. By application of Mie-scatter equations, the ratio of the absorption and scattering extinction measurements is demonstrated to yield solutions for the SMD. This work introduces the newly developed scattering-absorption measurement technique and highlights the important considerations that must be taken into account when jointly processing these measurements to extract the SMD. These considerations include co-alignment of measurements taken at different institutions, identification of viable regions where the measurement ratio can be accurately interpreted, and uncertainty analysis in the measurement ratio and resulting SMD. Because the measurement technique provides the spatial history of the SMD development, it is expected to be especially informative to the diesel spray modeling community. Results from this work will aid in understanding the effect of ambient densities and injection pressures on primary breakup and help assess the appropriateness of spray submodels for engine computational fluid dynamics codes.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu May 18 00:00:00 EDT 2017},
month = {Thu May 18 00:00:00 EDT 2017}
}

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  • A new technique is developed for the in-situ measurement of Sauter mean diameter of droplets in non-evaporating transient dense sprays. This method analyzes the image of a shadowpicture of a spray based on the incident light extinction principle, and allows the sizing of Sauter mean diameter of whole droplets in a transient spray with any shape. In addition, this method allows the measurement of the local droplet size in a quasi-steady region of an axisymmetric spray if the conservation equations regarding mass and momentum are included in the calculation and data analysis. A calibration was carried out using glass beadsmore » as test particles: this was proved to have an accuracy of Sauter mean diameter measurement within 10%, on average. Applications of the new technique to both diesel and gasoline (EFI) sprays have been made. The experimental results show that the rise in injection pressure contributes in the reduction of the overall Sauter mean diameter and that, in the peripheral region the droplets are smaller than those in the central region.« less
  • A mathematical model of combustion process in a diesel engine has been developed according to the theory of chain reactions for the higher hydrocarbon compounds. The instantaneous rates of fuel vaporization and combustion are defined in terms of the current values of temperature, pressure, concentration of fuel vapors, overall diffusion rate, fuel injection rate, and mean fuel droplet size in terms of the SMD. Numerical experiments have been carried out for investigating the interdependence between various combustion-related parameters. Specifically, the effect of fuel droplet size (in terms of SMD) on the subsequent combustion parameters, such as, pressure, temperature, thermodynamic propertiesmore » of air/gas mixture, heat transfer, fuel vaporization, combustion rate, current A/F ratio and gas mixture composition. In addition the integral indicator parameters of the engine, such as, mean indicated pressure, peak pressure, compression pressure have been analyzed.« less
  • Experimental data on the effects of CWS properties and air flow rate on mean drop size for simple pressure atomizers, were examined in our laboratory. A model equation which is derived based on the physical processes involved in air-pressure atomization is proposed. This equation demonstrates a good agreement with our experimental data.
  • Abstract not provided.
  • In the reported research work, the microscopic droplet velocity at different axial and radial locations downstream to the nozzle exit was studied by using a non-intrusive Laser Doppler Anemometry (LDA) techniques. These velocity measurements made in the viscous fluid spray sterams were used to predict the different breakup regimes in the flow. It was noticed that the droplet velocity decreased sharply downstream to the nozzle exit, whereas steady decrease in velocity was seen along the radial directions. For shorter injection time periods, the velocity downstream to the nozzle was not following the general breakup model. However, along the radial directionmore » it exactly followed the discussed model. Along the spray centerline, the velocity was decreasing sharply even at far points from the nozzle exit. It was difficult to identify the core region, transition region and fully developed spray region in the flow. It revealed that the jet breakup was not completed yet and further disintegration was taking place along the spray centerline for shorter injection periods below 250 ms.« less