Performance Evaluation of External and Mixed Compression Supersonic Air Intakes: Parametric Study

This research computationally evaluates the performance variations of two common types of supersonic air intakes, external and mixed compression, due to changes in the geometries of the intakes as well as some flow conditions. A computational fluid dynamics (CFD) solver was developed by the authors and used to simulate the compressible, two-dimensional (2D), and turbulent flow inside and around the supersonic air intakes. The main objective of this paper is to evaluate the role of geometric parameters, including spike angle, exit area, overall intake length, and flow parameters, such as the flight Mach number and back pressure ratio (BPR), on the performance of the intakes. Total pressure recovery (TPR), mass flow ratio (MFR), flow distortion (FD), and drag coefficient (${\mathrm{C}}_{\mathrm{D}}$) were considered as the performance factors of the supersonic intakes. The results indicated that increments of BPR had desirable effects on the performance of the intakes at supercritical conditions, and increments of the free-stream Mach number deteriorated the performance of both intakes. FD was the most sensitive parameter to the geometric variations, while TPR and MFR were almost unchanged. In addition, the superiority of the mixed compression intake was shown in terms of lower drag coefficient and FD in comparison with the external compression intake.