Generation of flame front turbulence

This article summarizes possible mechanisms of turbulence generation at the premixed flame front elucidated through recent studies. The aspects of flame front turbulence generated under various conditions are presented and the issues on current understanding of the mechanisms of turbulence generation are pointed out. Some mechanisms assumed to cause the flame induced turbulence are shown to be not effective for increasing the turbulence intensity at the flame front. Also, the scale of turbulence appearing on the flame front is discussed. Consideration of the lifetimes of vortices and of the process of flame front deformation is shown to be important for understanding the structure of turbulent premixed flames. The lifetimes of vortices smaller than the scale of the flame front disturbance caused by its instability are too short for these structures to be effective in enhancing the flame front turbulence. Thus. the minimum scale of the turbulence observable at the flame front would be comparable to that of the disturbance caused by flame front instability, and distributed reaction zones hardly appear even in high-intensity turbulent flames.