Simulation of the Concordant Control of Inlet-Sern of the Hypersonic Airbreathing Vehicle Under Off-Design Point

Abstract

It is an urgent requirement for a hypersonic airbreathing vehicle to fly over a wide Mach number, which will inevitably result in the troublesome on off-design point both to the inlet and exhaust system (usually the Single Expansion Ramp Nozzle, SERN). There has been a lot of research work considering the performance improvement about the inlet or SERN under off-design point separately, but very few have been conducted to concordantly deal with the inlet and the SERN at the same time. In this paper, the flow path of a hypersonic airbreathing vehicle similar to the X43-A, whose design point was at Mach 7 and flied over Mach 4 to 7, was numerically studied. In order to improve the aerodynamic performance of the vehicle under the off-design point, a tunnel between the inlet compression ramp and the SERN expansion ramp on the proper position was introduced. It was shown that the boundary layer with the low momentum air stream on the compression ramp was naturally sucked away to the expansion ramp with low pressure, which was served as a secondary flow injection. Consequently, the spillage of the inlet was diminished, and the overexpansion of the SERN was mitigated. Therefore, the aerodynamic performance of the whole vehicle was greatly improved. And the inlet could start now which could not if no suction tunnel was introduced. For the base model without the suction tunnel, the inlet cannot start, and the total pressure recovery coefficient, the captured mass flow rate of the inlet and the total axial force on the whole vehicle are 0.0833, 0.0902, and -5276 N(where “-” means drag), separately. Two good configurations with suction tunnel have been chosen, and the total pressure recovery coefficient, the captured mass flow rate of the inlet and the total axial force on the whole vehicle are 0.6591, 0.4432, and -3673 N, separately for configuration No. 1 , and 0.5597, 0.4586, and -4343 N, separately for configuration No. 2. Meanwhile, the mass flow suction rate is only about 3.36% and 2.21% of the theoretical captured mass flow of the inlet, respectively. So it seemed as a really good and promising means to resolve the offdesign point troublesome of the hypersonic vehicle over a wide operational envelope.