To analyze the aero-acoustic characteristics in open cavity influenced by inflow boundary-layer thickness

the cavity with length-to-depth ratio of 5.88 was simulated under conditions of different ratios of inflow boundary-layer thickness to cavity depth and inflow Mach number of 2.0

based on detached eddy simulation method; and the features of sound pressure level spectrum were obtained. The results show that increase of inflow boundary-layer thickness leads to enhanced stability in shear layer and decreased the oscillation amplitude stemmed from shear layer instability. This weakens the interaction between large scale vortex and supersonic main flow

causing the decrease in translational kinetic energy and rotation kinetic energy of large scale vortex. Responding to the energy decrease of large scale vortex

the maximum reduction of the sound pressure level inside the cavity is 7.5dB. Meanwhile

the tone frequencies have about 100Hz shift. A new formula with clarified physical meanings of empirical constant has been deduced from the Rossiter formula based on a new hypothesis. And the frequencies shift phenomenon can be illustrated by the new formula.