Asymptotic Analysis on the Extinction of Diffusion Flames in Supersonic Stagnation-Point Flow

Abstract

An asymptotic analysis is applied for the extinction of diffusion flames in supersonic stagnation-point flow. (It can be considered as the Tsuji-burner in a supersonic flow.) If airflow velocity is subsonic, the flame temperature decreases as airflow velocity increases because the flame stretch rate increases, and finally flame extinction takes place at a certain airflow velocity. However, in the case of supersonic airflow, the region in which a diffusion flame can be established between a detached shock wave and a porous body reappears, and flame extinction occurs when the airflow velocity decreases. This indicates shock heating has a stronger 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 sharply with Mach number of airflow.