Inlets of supersonic airplanes with deflection ramps

Abstract

Results are presented for various values of freestream Mach numbers. For each Mach number, the two-ramp optimal configuration for maximum recovery ratio is found and resulted in a higher maximum total pressure recovery ratio then that of the one-ramp system. Then, for a certain configuration and Mach number, the supersonic inlet, as well as the control volume around it, are geometrically modeled in Siemens NX 12.0. A mesh is generated in the control volume using the meshing program within Ansys. Numerical simulations of a supersonic flow over a two-ramp inlet system are conducted using Ansys Fluent 2019 R1. The most updated simulation results are presented showing the starting state of the inlet. However, within the simulations conducted, the inlet flow stays in the starting condition as opposed to the operational condition. Any attempt to move the shock wave downstream to the throat did not work. Further studies should investigate establishing simulations of the inlet operational situation.

Supersonic flight of aircraft at a higher speed than the altitude speed of sound has started in the middle of the 20th century and will continue into the future. This thesis studies the geometry of deflection ramps of inlet ahead of internal engines for airplanes flying at supersonic speeds. Their recovery total pressure ratio is defined as the total pressure at the exit of the inlet system over the freestream static pressure ahead of the inlet. The objective is to determine the one-ramp and two-ramp deflection angles, δ1 and δ2, of a two-dimensional, mixed compression supersonic inlet that produce the largest recovery total pressure ratio based on a given flight Mach number, M∞. Equations are presented for isentropic flow, normal shock waves and oblique shock waves. The inlet system is designed based on a starting situation, where there is a normal shock wave at the entrance, and an operational situation, where the normal shock wave moves to the throat. Computations for a one-ramp inlet configuration (for which δ2 = 0°) and a two-ramp inlet configuration are shown.