CHARACTERISTICS OF CAVITY IN REACTING FLOWS FOR SCRAMJET FLAME-HOLDER APPLICATION
Abstract
During the last few years, cavities have gained attention in the scramjet community as a promising flame-holding device. The present simulation study attempts to understand the reacting flow cavity characteristics for scramjet flame-holder application. The fuel was injected from upstream of cavity in reacting flow. Effects of cavity length to depth ratio were investigated. As the ratio of length-to-depth (L/D) is 3 or 4, the distribution form of the floor static-pressure of cavity in reacting flow is not consistent with that of cavity in non-reacting flow, even though open cavity flow occurs for the two cases. Open cavity flow occurs for L/D = 5, 6, 7 and 8 in non-reacting flow. Transitional cavity flow occurs for L/D = 5, 6 and 7, and closed cavity flow occurs for L/D = 8 in reacting flow. The flame holding capability of cavity with L/D = 7 is the best among all the cavities by comparison of the recirculation dimensions. Considering the drag of cavity, the cavity with ratio L/D = 5 is the best flame-holder among all cavities. The simulation results demonstrate that the cavity characteristics is different in non-reacting and reacting flows, and the conventional definition of cavity flow characteristics based on non-reacting flows needs to be revised accordingly.
