Effect of equivalence ratio and approach flow turbulence properties on the internal structure of premixed rod-stabilized flames

Abstract

Utilizing an instantaneous Rayleigh scattering technique, experiments were conducted to evaluate the separate influences of fuel-air ratio and approach flow turbulence properties on the internal structure of turbulent premixed V-shaped flames stabilized at the exit plane of a square burner. It is shown that an increase in the approach flow turbulent fluctuation velocities tends to reduce the instantaneous flame thickness. The spatial structure of the flame as described by the strength of the density fluctuations is found to be influenced by both equivalence ratio and turbulence intensity. Comparison of density fluctuation intensities with predictions from the Bray-Moss-Libby model indicates that the nature of the assumed pdf for closure of the governing equations can be influenced by both mixture stoichiometry and the properties of the approach flow turbulence.