Experimental and numerical investigation on a supersonic inlet with large bleed window

Abstract

The design of a two-dimensional supersonic inlet with large bleed window at low Mach number was developed. Numerical simulation and wind tunnel experiments were carried out to investigate the aerodynamic performance and variable geometric rules of the inlet. The result indicates that the single-degree-of-freedom variable geometry scheme adopted in this paper guarantees the steady work of the inlet over a wide speed range. The large bleed window caused by rotation of the compression ramp appears near the throat at low Mach number. Low-pressure airflow near the bleed window neutralises the original high-pressure airflow behind the shock train, which decreases the overall pressure of the downstream region of the internal contraction section. To match the lower pressure, the structure of the shock train changes from strong $\lambda$ -type to weak $\lambda$ -type, and finally to a normal shock wave as backpressure increases at Mach number 2.5. Herein, the total pressure recovery coefficient of the inlet near the critical condition improves by 8.5% as the backpressure ratio (Pe/P0) adds from 13 to 14.6 at Mach number 2.5. It proves that the scheme is effective on terminal shock wave control and inlet performance improvement. In addition, due to the background wave and the bleed window, two kinds of shock wave oscillation occur when the backpressure ratio is 13.1.

Aerodynamic Instabilities in High-Speed Air Intakes and Their Role in Propulsion System Integration

“…Other studies have combined the bleed system with other flow control methods, such as vortex generators [122], plasma injection [123], mesoflap [124] and cavity [125]. For the second problem, recent studies [126][127][128][129] have examined a new bleed system design, mostly in steady-state conditions, consisting of multiple parallel slots. With a multi-slotted bleed system located upstream of the intake throat, sufficient flow spillage occurs that discharges the excessive captured airflow.…”