ASYMPTOTIC ANALYSIS ON THE EXTINCTION OF DIFFUSION FLAMES IN SUPERSONIC STAGNATION-POINT FLOW

An asymptotic analysis is applied for the extinction of diffusion flam es in supersonic stagnation-point flow. (It can be considered as the T suji-burner in a supersonic flow.) If airflow velocity is subsonic, th e flame temperature decreases as airflow velocity increases because th e flame stretch rate increases, and finally flame extinction takes pla ce at a certain airflow velocity. However, in the case of supersonic a irflow, the region in which a diffusion flame can be established betwe en a detached shock wave and a porous body reappears, and flame extinc tion occurs when the airflow velocity decreases. This indicates shock heating has a stranger effect than high stretch-rate flow and dominant parameter for the phenomena is a temperature behind a detached shock wave. Moreover, it is clarified that the flame temperature rises sharp ly with Mach number of airflow.