TITLE:

Direct Numerical Simulations of Turbulent Premixed Flames

DATE:

Friday, September 4th, 2015

TIME:

3:30 PM

LOCATION:

GMCS 214

SPEAKER:

Dr. John Abraham. Department of Mechanical Engineering, San Diego State University

ABSTRACT:

Determination of the premixed turbulent flame speed, defined as the propagation speed of a flame front through a homogeneous turbulent mixture, and its dependence on the turbulent field properties, has remained a fundamental problem in combustion science. The turbulent flame speed can be straightforwardly determined via Direct Numerical Simulations (DNS) but at great cost: fine resolution is required for resolving the Kolmogorov scale and even finer resolution for resolving the reaction zone while the domain needs to be sufficiently large to capture multiples of integral length scales; in addition, several realizations may be required to achieve statistical convergence on the estimation of the flame speed, resulting in prohibitively expensive computations. This talk will discuss a computational approach to simulate the turbulent premixed flame propagation in the frame of reference of the flame front itself, relying on an inflow/outflow configuration. The steady turbulent burning velocity is obtained once the flame front becomes statistically stationary inside the domain. Using this approach, DNS of premixed turbulent flames in lean mixtures are carried out and the dependence of the turbulent flame speed on the turbulent flow field characteristics are investigated. It is shown that correlations that are available in the literature do not reproduce the computed flame speed results, suggesting that the understanding of the independent parameters on which the speed depends is far from complete.

HOST:

Dr. Jose Castillo

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