Numerical Analysis on Supersonic Flow Past Partially Covered Cavities

The cavity flow studies have been one of the most interesting areas in fluid dynamics, as it involves complex physical phenomenon such as hydro dynamic instability and acoustics response. High speed flow over cavities generates intense pressure fluctuation and compressive waves within the cavity. In the present work, an un-covered and partially covered cavity was considered for the analysis to understand the variations in the fundamental flow behavior when flow experiences a change in the geometry. The partially covered cavities are widely used in landing gear bays, Helmholtz resonator and flame holders in high speed combustion system. The mechanism and the acoustic response of the partially covered cavity is different from that of a baseline uncovered cavity and thus a detailed study is essential for designing an effective flow oscillation suppression technique. The hydrodynamic and acoustic nature of flow around rectangular cavities with and without cover configurations were investigated considering an inflow Mach number of 2.5 and L/D of 7 whereas the Reynolds number based on cavity depth (ReD) is 45000. The simulations were performed using ANSYS Fluent. The lid on the cavity mouth near the leading and trailing edge affects the overall pressure distribution in and around the cavity. The instabilities associated with the presence of lid along the shear layer near the leading and trailing edge becomes the source for thinning of the shear layer and the production of small scale structures which makes the flow more intricate. The result reveals that, a significant variation in the flow oscillation mechanism occurred due to the presence of lid along the shear layer near the fore and the aft edge of the cavity. The formation of shear layer, compressive waves, their mutual interactions and associated acoustic generation were resolved.