On the validity of the wrinkled front model of moderately turbulent flames

Abstract

A technique for measuring the saturation current was applied to premixed laminar and turbulent methaneoxygennitrogen flames. The burner was taken as the anode and the cathode was an air-cooled spiral of copper tubing matched with the shape of the laminar or turbulent flame front. This geometry of the electrodes allowed us to measure, for the first time to our knowledge, the large values of the saturation current in stoichiometric premixed turbulent methaneoxygennitrogen flames at burner Reynolds numbers in the range 1000–7000. When the saturation currents measured are plotted versus the mean gas velocity, no discontinuity occurs at the transition between laminar and turbulent conditions, and the shape of the curves obtained strongly suggests that the effect of the turbulence is essentially to distort a flame front which keeps its laminar character. This result is in close agreement with experiments performed by Hurle et al., who followed the variations of the intensity of the total C 2 ∗-chemiluminescence as a function of the total gas flow rate in laminar and turbulent premixed ethylene-air flames of similar type.