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Title: Afterburning and Combustion in Explosions in Barometric Calorimeters

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Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
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Conference: Presented at: 21st ICDERS, Poitiers, France, Jul 23 - Jul 27, 2007
Country of Publication:
United States

Citation Formats

Reichenbach, H, Neuwald, P, and Kuhl, A L. Afterburning and Combustion in Explosions in Barometric Calorimeters. United States: N. p., 2007. Web.
Reichenbach, H, Neuwald, P, & Kuhl, A L. Afterburning and Combustion in Explosions in Barometric Calorimeters. United States.
Reichenbach, H, Neuwald, P, and Kuhl, A L. Thu . "Afterburning and Combustion in Explosions in Barometric Calorimeters". United States. doi:.
title = {Afterburning and Combustion in Explosions in Barometric Calorimeters},
author = {Reichenbach, H and Neuwald, P and Kuhl, A L},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu May 31 00:00:00 EDT 2007},
month = {Thu May 31 00:00:00 EDT 2007}

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  • During the early stages of spherical turbulent flame propagation, more than half of the gas behind the visible flame front may be unburned. Previous models of the afterburning of the gas behind the apparent flame front have been extended in the present work, to include the effects of flame quenching, consequent upon localized flame stretch. The predictions of the model cover, the spatial and temporal variations of the fraction burned, the flame propagation rate, and the mass burning rate. They are all in dimensionless form and are well supported by associated experimental measurements in a fan-stirred bomb with controlled turbulence.more » The proportion of the gas that is unburned decreases with time and increases with the product of the Karlovitz stretch factor and the Lewis number. Simultaneous photographs were taken of the spherical schlieren image and of that due to Mie scattering from small seed particles in a thin laser sheet that sectioned the spherical flame. These clearly showed the amount of unburned gas within the sphere and, along with other evidence suggest laminar flamelet burning across a scale of distance which is close to the Taylor confirm the predictions of the fraction of gas unburned and of the rate at which it is burning.« less
  • Thermodynamic states encountered during afterburning of explosion products gases in air were analyzed with the Cheetah code. Results are displayed in the form of Le Chatelier diagrams: the locus of states of specific internal energy versus temperature, for six different condensed explosives charges. Accuracy of the results was confirmed by comparing the fuel and products curves with the heats of detonation and combustion, and species composition as measured in bomb calorimeter experiments. Results were fit with analytic functions u = f ( T ) suitable for specifying the thermodynamic properties required for gas-dynamic models of afterburning in explosions.
  • A theoretical model of afterburning in explosions created by turbulent mixing of the detonation products from fuel-rich charges with air is described. It contains three key elements: (i) a thermodynamic-equilibrium description of the fluids (fuel, air, and products), (ii) a multi-component gas-dynamic treatment of the flow field, and (iii) a sub-grid model of molecular processes of mixing, combustion and equilibration.
  • A control installation is described for the dosing or proportioning of a secondary air quantity for the improvement of combustion in internal combustion engines, or the after-burning of the exhaust gases of internal combustion engines. An auxiliary arrangement is responsive to an emergency signal for effecting the prompt shutting-off of the secondary air. The emergency signal may be initiated in response to a failure in the ignition voltage of the internal combustion engine; an increase in the hydrocarbon content of the exhaust gases; a disparity between the position of the mixture dosing element and the engine rotational speed; the exceedingmore » of a limiting temperature in the exhaust gas manifold; or the exceeding of a limiting temperature in the afterburner.« less