Supersonic diffusers with reverse flow injection

In applications such as airborne high energy chemical lasers, diffuser size and weight can be critical parameters. This paper summarizes research concerning the effects of flow injection into a supersonic diffuser in a direction opposite to that of the main flow. Experimental studies were conducted concerning the effect on diffuser performance, particularly length and pressure recovery, of this reverse flow, and a quasi-one-dimensional control volume analysis was performed to predict some of the diffuser flow properties. Single-stream, dual-stream, and sudden enlargement configurations were considered. This work has shown that a reverse flow can reduce the length of a diffuser while causing only a small decrease in overall pressure recovery.