Numerical simulation on aerodynamic performance of dorsal S-shaped inlet

Inlet distortions of the engine at high-angle-of-attack flight conditions have become a major concern for scholars. The aerodynamic performances of a dorsal S-shaped inlet of unmanned aerial vehicle (UAV) engine at different flight conditions are simulated in the current work, based on 3D computational fluid dynamic (CFD) method with NUMECA software. The flows through the inlet and the distortions are simulated and analyzed under the condition of 7 different angles-of-attack from negative 5 degrees to positive 25 degrees with the Mach number fixed at 0.45. The CFD simulation results demonstrate that with the angle-of-attack increasing, the total pressure recovery ratios and the mass-flow rates decrease. While on the contrary, the distortions of the circular and radial steady total pressure increase. Under the conditions of the high-angles-of-attack, the pass-through capacity of the flow is weakened, the pass-through capacity of the flow is weakened, and the secondary flow is strengthened. At the same time, large flow separation occurs at high angle-of-attack.