Root pulsation of premixed turbulent flames

In order to analyze the root pulsation and its effect on flame stabilization, planar laser induce fluorescence is used to collect the instantaneous shape of Bunsen premixed turbulent flames. In this paper turbulence is generated by perforated plate and blocked-ring so that potential turbulence and boundary layer turbulence are formed separately. The results show that in both turbulence generators, the pulsation amplitude of flame root increases with the increase of incoming velocity. Besides, increasing the characteristic length of the turbulence generator or decreasing the fuelair ratio of the premixed gases will enlarge the pulsation amplitude of flame root. The variation of the blocked-ring scale shows the existence of a critical length. When the blocked-ring scale is shorter than the critical length, the pulsation of flame root goes against flame stabilization, and flame blowoff velocity decreases with the increase of blocked-ring scale. Oppositely, when the blocked-ring scale is greater than the critical length, flame blowoff velocity increases with the increase of blocked-ring scale. Accordingly, turbulence generation region has great effect on flame blowoff velocity.