Numerical analysis on the conceptual design of an air-breathing engine inlet working in mach number 3∼5.5

Abstract

Based on the equal-intensity shock theory, this article designed a supersonic inlet working in Mach number 3.0∼5.5 with the background of an air-breathing engine. The inlet applied the four-shock train mixed compression configuration and inserted a sidewall compression at the beginning of the isolator. Through developing effective 3D RANS computations validated by current experiments, the performance of the designed inlet was identified. The designed inlet self-starts at freestream Mach number Ma∞ = 3.0 under which the total pressure recovery coefficient has dramatic increment, and the aerodynamic choking at the inlet throat no longer presents; the inlet keeps working at all studied flight states with zero angle of attack (AoA) and achieves shock-on-lip at the design point Ma∞ = 5.0. Both positive and negative AoAs can disrupt the equal-intensity shock allocations, which degrade the inlet performance. The inlet obtains maximum total pressure recovery coefficient at zero AoA. The maximum back pressure at Ma∞ = 3.0∼5.5 obtained by the inlet surpasses the requirements and keeps a certain margin. The inlet performance basically meets all the goals proposed by the engine.

Self-Start Characteristics of Hypersonic Inlet When Multiple Unstart Modes Exist

“…Regarding the conventional unstart mode, at most times, inlet self-start can be completed through increasing the Mach number [22][23][24]. Because decreasing the angle of attack (alpha) increases the Mach number in front of the inlet, self-start can also be achieved through this process [25,26].…”