A study on the local flame displacement velocity of premixed turbulent flames

Abstract

The local flame properties of turbulent propagating flames with respect to the ratio of the turbulence intensity to the laminar burning velocity u′/S L0 in the flamelet regime have been investigated experimentally for methane, propane and hydrogen mixtures having nearly the same laminar burning velocity with different equivalence ratios. u′/S L0 is varied as 1.4 and 2.3. A 2D laser tomography technique is used to obtain the flame configuration and movement in a constant-volume vessel and then the local flame displacement velocity S F is quantitatively measured as a key parameter of turbulent combustion. As a result, the mean value of S F shows to be affected by u′/S L0, which indicates a relation between the characteristic chemical reaction time and the characteristic flow time, to some extent, especially for leaner and richer mixtures. S F is also discussed by the concept of preferential diffusion and Markstein number which can affect the local burning velocity characteristics.