Flow-Based Prediction for Self-Starting Limit of Two-Dimensional Hypersonic Inlets

Hypersonic inlet self-starting ability is of great importance for scramjet engines and hypersonic flight vehicles to operate stably and efficiently. However, the prediction of the hypersonic inlet self-starting limit is generally difficult. This paper proposes a flow-based prediction approach for the self-starting limiting internal contraction ratio of two-dimensional hypersonic inlets. The key lies in the establishment of a general approximate expression for the fluid dynamic blockage, caused by the migration of the primary separation bubble down the internal contraction portion of the inlet. Formulas for the fluid dynamic blockage and the limiting internal contraction ratio are given. The predicted results are in good agreement with the published experimental results on hypersonic inlet starting.