Flow Mechanism in a Hypersonic Sidewall Compression Inlet with a Rectangular-to-Circular Isolator

Abstract

The flow phenomenon and mechanism in sidewall compression hypersonic inlets with a rectangular-to-circular isolator are investigated in this paper. The two schemes were introduced to study the flowfield of the inlets with rectangular-to-circular cross-section shape transition. The results show that 1) the gross performance of inlets with a rectangular-to-circular isolator are better than the original inlet; 2) the common feature of the crossflow in the isolator of the three schemes is the existence of a pair of counter-rotating flow-directional vortices near the bottom wall, rotating on the boundary layer toward each other; 3) scheme 3 has a stronger sidewall vortex than scheme 2 (it produces a rolldown effect to improve the low-speed flow and the corner flow); and 4) the rectangular-to-circular process on sidewall compression inlets does not affect the startability. The backpressure limit of scheme 1 is the highest, which is significantly higher than schemes 2 and 3. This is mainly because the boundary layer accumulates more easily near the bottom of the symmetry plane in the schemes with a rectangular-to-circular process.