Effects of Cowl Lip Angle on Starting Performances for a Mixed-Compression Two-Dimensional Axisymmetric Hypersonic Inlet

Abstract

The third quasi-uniform B-spline was adopted to design the cowl profiles with various cowl lip angles. Starting performances were simulated by the numerical method and the results showed that the starting processes for different cowls can be classified into two types. In the first type, the inlet starts when the opened large-scale separation zone is swallowed; in the second type, the opened separation zone enters the internal contraction region to form a closed separation zone, which is then swallowed to enable the start. In addition, inlets with small and large cowl lip angles exhibit the first and second types of the starting process, respectively. Moreover, there is an optimal cowl lip angle to achieve the best starting performance. For the inlet investigated herein, the starting Mach number is the lowest when the cowl lip angle is 9°. In addition, as the internal contraction ratio increases, the optimal cowl lip angle gradually decreases and the starting performance deteriorates.