Simultaneous Measurements of Concentration and Velocity in an Open Premixed Turbulent Flame

Abstract

Measurements have been made in the turbulent premixed flame in an LPG/ air mixture issuing from a 50 mm diameter pipe. The flame was of the classical bunsen type with a half cone angle of 16° Measurements were made along a line at an angle of about 50° to the normal to the flame front. Concentration, or the progress variable c, was measured by the light scatter technique and velocity u by laser Doppler velocimetry. The correlation between u and c is found to be positive through much of the flame indicating a counter-gradient flux. The joint probability density function (pdf) of u and c is well modelled by essentially burnt and unburnt gas with only a small contribution of the partially reacted gas. The conditioned pdf' s for velocity in the unburnt and burnt gas show a considerable increase in both mean and variance for the burnt gas.