A numerical study on shock induced distortion, mixing and combustion of flame

Flame distortion induced by shock waves frequently occurs in natural and man-made phenomena. To deeply understand the characteristics of flame distortion and the resulting variations of mixing and combustion, a two-dimensional numerical study of a spherical flame distortion induced by a planar incident shock wave and its reflected wave was carried out by using the Navier-Stokes equations coupled with a single-step chemical reaction and the high resolution of grid. The numerical results are in agreement with the experimental results. It can be found that before the interaction of reflected shock wave with flame, the distortion and crinkle of flame are mainly affected by the induction of incident shock wave, which means the physical process plays an important role; while after the interaction between reflected shock wave and distorted flame, the reaction heat release rate and the effective area and edge length of flame increase quickly, the controlling mechanism of flame distortion is transforming from the physical process to the chemical reaction (combustion) process; in the later stage of the evolution of distorted flame, enhanced combustion can weaken the crinkle of flame interface, and therefore inhibit the mixing process between unburned and burned gases. It is concluded that the mixing between unburned gas and burned gas is promoted via the distortion of flame, which can strengthen the combustion process, however, the enhanced combustion inhibits the mixing in the later stage. It is significant for understanding the relationship between mixing and combustion in using or controlling the shock-flame interactions.