A Critical Study of the Bray-Moss-Libby Model

Abstract

An analytical formula has been derived for the turbulent diffusivity at the leading edge of a stationary turbulent planar flame, described by the Bray-Moss-Libby (BML) model- The formula is derived from an expression for the turbulent burning velocity, formulated by Hakberg et al. (1993) and validated in the case of negligible heat release. The turbulent diffusivity at the leading edge depends on the straining of the flame front, for the BML flamelet model, but is close to the cold flow diffusivity in the limit of high rates of strain.

A three dimensional, compressible Navier-Stokes solver, developed by Trouve and Poinsot (1994), has been used to determine the mean reaction rate, the spatial flamelet crossing frequency, the flame surface density, the flamelet orientation factor and the BML integral length scale. Comparison between the integral length scale determined from an empirical flame velocity correlation and DNS data gives a fair agreement.

Keywords:

• Turbulent flames
• turbulent flame models
• flamelet models
• direct numerical simulation