Numerical Investigation of Autoignition Regionin a Supersonic Combustor

The present paper deals with the numerical investigation of autoignition region between a backward-facing step and perpendicular wall injectors in a supersonic combustor. A series of simulation changing the dynamic pressure ratio of the injectant to the main stream is carried out. Wall pressure profiles and injectant concentration in the recirculation region between the step and the injectors show agreement with experimental results. The results by tracking streamline clarifies the correlation between the ratio of circulating cycle to the variation of injectant concentration in the horseshoe vortex and the residence time of mixture measured at the fixed point. The residence time increases from 0.3 msec at the dynamic pressure ratio of 0.1 to 1.2 msec at 0.7. When the dynamic pressure ratio exceeds 0.7, the residence time becomes constant because the size of the horseshoe vortex and injectant concentration does not vary.