Propagation of large scale premixed turbulent flames
type: CreativeWork
description: We examine premixed turbulent combustion within the context of a hydrodynamic model derived from physical first principles. This is an asymptotic model that exploits the multi-scale nature of the problem, characterized by two disparate length scales: the diffusion length scale representing the flame thickness and the hydrodynamic length scale associated with the dimensions of the combustion chamber. It treats the flame as a surface of density discontinuity that separates the burned gas from the fresh combustible mixture and propagates relative to the unburned gas at a speed that depends on the local stretch rate - a measure of the deformation of the flame front that depends on the local curvature and hydrodynamic strain rate that it experiences. The dependency on stretch rate is modulated by a Markstein length, a parameter of the order of flame thickness that mimics the effects of diffusion, mixture strength and stoichiometry. In an experimental setting, a change in the value of Markstein length can be brought about by varying the fuel type and mixture composition or through variations in system pressure. A numerical methodology was developed for the implementation of this model that requires a surface tracking algorithm for the evolution of the flame front combined judiciously to a Navier-Stokes solver for the variable density fluid-dynamical equations. Such a hybrid algorithm is developed and utilized to study premixed turbulent flame propagation, with an aim of providing a deeper insight into the mechanisms governing flame-turbulence interactions. In particular, this approach is used to systematically address the fundamental problem of determining the turbulent flame speed, a problem that has been at the forefront of combustion research for several decades. The turbulent flame speed, defined as the mean propagation speed of a premixed flame in a turbulent environment, is of great practical importance being directly related to the mean fuel consumption rate in a g…
abstract: We examine premixed turbulent combustion within the context of a hydrodynamic model derived from physical first principles. This is an asymptotic model that exploits the multi-scale nature of the problem, characterized by two disparate length scales: the diffusion length scale representing the flame thickness and the hydrodynamic length scale associated with the dimensions of the combustion chamber. It treats the flame as a surface of density discontinuity that separates the burned gas from the fresh combustible mixture and propagates relative to the unburned gas at a speed that depends on the local stretch rate - a measure of the deformation of the flame front that depends on the local curvature and hydrodynamic strain rate that it experiences. The dependency on stretch rate is modulated by a Markstein length, a parameter of the order of flame thickness that mimics the effects of diffusion, mixture strength and stoichiometry. In an experimental setting, a change in the value of Markstein length can be brought about by varying the fuel type and mixture composition or through variations in system pressure. A numerical methodology was developed for the implementation of this model that requires a surface tracking algorithm for the evolution of the flame front combined judiciously to a Navier-Stokes solver for the variable density fluid-dynamical equations. Such a hybrid algorithm is developed and utilized to study premixed turbulent flame propagation, with an aim of providing a deeper insight into the mechanisms governing flame-turbulence interactions. In particular, this approach is used to systematically address the fundamental problem of determining the turbulent flame speed, a problem that has been at the forefront of combustion research for several decades. The turbulent flame speed, defined as the mean propagation speed of a premixed flame in a turbulent environment, is of great practical importance being directly related to the mean fuel consumption rate in a g…
author: Fogla, Navin
language: en
keywords: premixed turbulent flames, hydrodynamic theory, turbulent flame speed, Darrieus-Landau instability
date published: 2015-01-21T19:55:05Z
date modified: 2026-07-22T22:26:07Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/72969