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On the dynamics of the collapse of a diffusion-flame hole

Pantano, C. and Pullin, D. I. (2003) On the dynamics of the collapse of a diffusion-flame hole. Journal of Fluid Mechanics, 480 . pp. 311-332. ISSN 0022-1120. http://resolver.caltech.edu/CaltechAUTHORS:PANjfm03

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Abstract

The collapse dynamics of a diffusion-flame hole in the presence of a counterflow are studied. We construct unsteady solutions of the one-dimensional edge-flame model of Buckmaster (1996), in which heat and mass transverse losses are algebraic. The flame structure is determined in the classical limit of large activation energy. Solutions for both planar and axisymmetric strain geometry are considered for the particular case of unity Lewis number. It is shown that the final stage of the edge-flame collapse is determined by a dominant balance between the time rate of change of the mass fractions (and temperature) and diffusion, giving a self-similar structure in which the size of the edge-flame hole approaches zero, to leading (zeroth) order, as a 1/2-power of time. This solution suggests an expansion of the full model equations in 1/2-powers of time that allows detailed analysis of the effects of side losses and flow distribution in the edge-flame collapse process. It is found that side loss effects are apparent at the first order, whereas convection by the counterflow is first felt during collapse at the second order in the fractional-time expansion. Numerical integrations of the governing equations are found to verify the analytic results.


Item Type:Article
Additional Information:Copyright © 2003 Cambridge University Press. Received September 19 2002; revised November 14 2002. This work was supported by the Academic Strategic Alliances Program of the Accelerated Strategic Computing Initiative (ASCI/ASAP) under subcontract no. B341492 of DOE contract W-7405-ENG-48.
Subject Keywords:EDGE-FLAMES; MIXING LAYERS; TRIPLE FLAME; PROPAGATION; COUNTERFLOW
Record Number:CaltechAUTHORS:PANjfm03
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:PANjfm03
Alternative URL:http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=149593#
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6746
Collection:CaltechAUTHORS
Deposited By: Lindsay Cleary
Deposited On:20 Dec 2006
Last Modified:26 Dec 2012 09:24

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