A Study of the Mixing Characteristics for Cavity Sizes in SCRamjet Engine Combustor

Recently, interest has been shown in utilizing hypersonic vehicles for the purpose of flight transfer to supersonic or hypersonic. In particular, the SCRamjet Engine which is the propulsion system for a hypersonic vehicle has been studied to see if it is able to run. However, most research related to the SCRamjet doesn't provide detailed results. Therefore, the result of SCRamjet research is done in an e-science AHM in order to share advanced resources and to allow collaborative research. Airflow into the combustor of a scramjet engine stays inside for a very short time i.e. on the order of milliseconds. Since the whole process of combustion has to be completed during this short duration, research on supersonic combustion technologies is of great significance. Of the many technologies, this study is concerned with methods that improve the air-fuel mixture efficiency. By selecting a method that uses a cavity and vertical jet injection, this study investigates the characteristics of the flow field by using both numerical analysis and experimental methods. The cavity size alone is varied while the length-height ratio (L/H) of the cavity is fixed at 1, and the sonic jet is injected vertically through a 1-mm-diameter nozzle downstream of the cavity. A numerical analysis reveals that larger cavities correspond to larger vortices, which is a measure of the air fuel mixture. Specifically, near the bottom of the combustor (y/D = 5), where mixing is most active, large vorticities are seen. Furthermore, for a comparison and verification of the results of the numerical analysis, visualization using shadowgraphs and measurements of the pressure using pressure sensitive paint (PSP) are conducted in the supersonic wind tunnel at Konkuk University. Allowing for better understanding of the physics of the flow, the visualization results show good qualitative agreement with regards to the shape of the shockwaves and changes in the shear-layer thickness while the results from the pressure measurements confirm that the analysis results are close to the experimental results.