Flowfield in a Model Scramjet Combustor in Case of Injecting Fuel Perpendicularly behind the Backward-Step.

Experimental and numerical investigations are performed to clarify the flowfield in a model scramjet combustor with a backward-step in case of injecting fuel perpendicularly behind the step. The airflow total temperature is 1, 800 K and the Mach number is 2.0. The backward-step, which generates high Damkohler number (Da) region, is expected to work as a flame-holder. However, when the precombustion shock wave (PSW) is absent, the recirculation zane behind the step and the region downstream the fuel injector are divided by low Da region, and the reaction in the recirculation zone and that downstream the fuel injector occur independentiy, therefore, the recirculation zone cannot work as fiarne-holding region. The presence of the PSW enlarges the recirculation zone and connects the above two regions by relatively high Da region, and allows the step to work as a flame-holder. Therefore, for the design of the backward step, not only the proper arrangement of the step and the fuel injector but the use of PSW is essential particularly in the low airflow total temperature.