Laminarization of flames in rotating flow

Abstract

The mechanism of turbulent flame propagation in rotating flow was studied for homogeneous,premixed methane-air mixture. The experiments were performed in a 70 mm dia. and50 mm wide constant pressure cylindrical combustion chamber with high schlieren quality glasswindows. The maximum tangential velocity range was 30-90 m/s and maximum Lm.S. turbulentvelocity range 2-10 ra]». It was shown that turbulent burning velocity in swirl, contrary to turbulentburning velocity in non-rotating mixture, depends weakly on the Lm.S. turbulent velocityof flow. Turbulent burning velocity approaches or only slightly exceeds the value of the laminarburning velocity over the entire burning range (values of 0.1 to 0.7 m/s in rotating flow againstseveral mjs in non-rotating flow). Laminarization of turbulent combustion appears when theFroude number Fr=v'!./ll·L approaches the range 0-004, where u denotes the r.m.s. turbulentvelocity, a the centrifugal acceleration, and L the integral scale of turbulence.