Cavity flows have been the subject of aerodynamic research since the early days of high-speed aircraft with internal store carriage in the 1950s. Low observability design requirements for current combat aircraft has renewed the interest in this field. The presence of an open cavity, such as a weapon or undercarriage bay, exposed to a high-speed grazing flow can result in severe pressure fluctuations. These pressure fluctuations can reach intensities of up to 165dB SPL and may cause damage to both the aircraft and to any sensitive components within the bay. Results for this study were generated using an existing generic rectangular planform cavity wind tunnel model, designated as M219/1. This small scale model was the forerunner for the more widely known larger scale M219 generic cavity model.
Numerical simulations were performed for two geometries, the 38mm and 80mm deep cavities, at a freestream Mach number of 0.80. In order to capture the unsteady flow behaviour in the cavity, a time accurate detached eddy simulation (DES) model was run which uses Reynolds averaged Navier-Stokes (RANS) near to the wall to reduce computational cost and a large eddy simulation (LES) model in the separated flow region far from the walls.Continue reading