Numerical investigation of the strong interplay between a cavity and a store under supersonic inflow condition is conducted by using Improved Delayed Detach-Eddy Simulation (IDDES). Pressure fluctuations in the cavity are analyzed with smooth pseudo Winger-Vile distribution method and the time-frequency features are obtained. The effects of fluctuating flow inside the cavity on the aerodynamic loads of the store are also studied. It was shown that when the store is falling through the shear layer, the self-sustained oscillation loop is destroyed and the cavity tone vanishes. Vortex structures concentrate in the back of the cavity, as a result the noise levels at the rear of the cavity increase. After the store falls out of the cavity, the oblique shock wave formed at store's head interferences with the shear layer, which changes the cavity tone frequencies. The forces and moments acting on the store fluctuate strongly influenced by highly unsteady flow-field. Affected by oblique shock and the impact of shear layer, the store's pitch up angle keeps rising up and reaches to 24° at its maximum.
