Flow in a high-velocity mixed compression inlet studied by the RANS/ILES method in different operation modes

The separated flows taking place in different-geometry diffusers and in a high velocity inlet have been studied by the Reynolds Averaged Navier-Stokes-Implicit Large Eddy Simulation (RANS/ILES) method. The presented modified method makes it possible to increase the computation accuracy of separated areas and attached boundary layers. The flows in a model inlet of mixed compression with a rectangle cross section are calculated for incoming flow Mach number of $5.9$ on a grid with $4.13 \times 10^6$ cells, beginning with a mode without throttling and finishing with buzz mode. The boundary where the inlet becomes unstable, if throttling is increased, is determined. The relationship of the pressure on time at the upper wall of the inlet isolator channel for all modes, including the buzz mode, is compared with the experimental one. The correlation between inlet throttling and buzz frequency is revealed. The performance curve is determined. The experimental and calculated results are in good agreement for all available experimental parameters for the examined inlet. The presented method demonstrates higher accuracy with respect to the calculations performed by the LES method on the fine grid of the examined inlet.