Diffusion flames in opposed counter-rotating jets

In this study, we present the results of our experimental investigation of the behavior of methane and butane diffusion flames in counter-rotating opposed-jet flow. The variations of flame temperature and position as functions of the jet angular velocity ω are reported. Also, using the previously developed theory for non-reactive, inviscid flow field, the flame extinction data are correlated with the stretch rates experience by the flames. The calculated critical values of ω corresponding to the minimum fuel concentration at extinction are found to be in close agreement with the experimental observations. It is established that the Lewis number of the mixture has a pronounced effect on the behavior of diffusion flame within the recirculating secondary flow. The relevance of the results to the understanding of turbulent diffusion flames is discussed.