Dynamics and morphology of colliding spherical flames

A preliminary experimental and computational study was conducted on the dynamics and flame morphology of two identical colliding spherical flames. Experimentally, premixtures of fuel (C2H6, C3H8) and air are ignited by two synchronized sparks in a closed chamber under atmospheric pressure, with the subsequent flame front evolution tracked by a Schlieren system with high-speed camera. The images yield three distinctive stages during collision, namely: independent propagation, interface flattening and corner dynamics. The evolution of the total surface area and flame distortion is evaluated. Results show that the Lewis number dependence of the flame propagation speed at the corner is opposite to that expected of the thermal-diffusional effect, thereby demonstrating that Huygens' propagation dominates over the effects of stretch-affected preferential diffusion. Simulation shows that the flow field is largely distorted around the flame corner, causing pressure redistribution and vorticity generation through the baroclinic force across the flame.