Numerical investigation of rear wall effect in supersonic cavity flow using OpenFOAM

High velocity flows over cavity regions representing the places where new generation fighter aircrafts position weapons are difficult to understand, complex, time-dependent and involve highly turbulent structures, which are frequently encountered in aviation applications, and are an essential problem to be solved. In this direction, there are many numerical and experimental studies in the literature. In this study, a numerical analyzes of a rectangular open cavity flow with free stream velocity between 1.4 Mach and 1.8 Mach in supersonic regime are performed using Computational Fluid Dynamics (CFD). Time dependent Reynolds Averaged Navier Stokes Equations for two-dimensional, turbulent, compressible flow are solved using OpenFOAM, an open source code. The results are presented in terms of pressure coefficients and sound pressure levels for the rear and bottom wall, which are the critical regions of the cavity. Passive control methods have been applied to the flow in order to reduce the pressure fluctuations and sound pressure levels caused by high velocity flow and turbulence in the cavity region. Within the scope of the passive control methods, parametric modifications are made in the geometry of the rear wall which is the most critical part of the cavity, in order to reduce the noise levels generated in the cavity. These parametric studies are geometrical changes such as inclination of rear wall of the cavity, creating a crescent geometry on the rear wall of the cavity and shortening the rear wall height of the cavity. Due to the reduction of the interaction between the shear layer and the cavity rear wall, sound pressure levels are decreased. Systematically, parametric optimization studies are carried out with combinations of the best rear wall geometries that reduce noise levels. As a result of the studies, the ideal cavity configuration with the best noise levels is obtained. Finally, the effects of different Mach numbers on the flow in the supersonic regime have been investigated for best results. The reliability of the CFD solver OpenFOAM used in this study has also been proven for supersonic cavity studies.