Flow characteristics of small-sized supersonic inlets

The flow characteristics were investigated for two types of small-sized supersonic inlet models: Rectangular and axisymmetric inlets. The two models were designed by the same method and are of similar size, with a total length of about 160 mm. The flow phenomena that were generated at the stable and unstable operating conditions of both models are visualized and discussed in detail. The main flow feature for stable operation is the existence of a shock train induced by the shock boundary-layer interactions. The results show that the shock-train shape and position are varied along with the upstream and area ratios, which strongly impact the downstream flow and total pressure recovery. For unstable operation, various buzz phenomena are observed for different area ratios. The results indicate that the buzz phenomenon of the small-sized inlet is identical to that of a large inlet, but the small inlet can be easily affected by the presence of a separation bubble. Although the shapes of the inlets are different, the base frequencies of a big buzz for both models are very similar. The role of the separation on the compression surface in the buzz process of the small-sized inlet is shown.