Analysis and validation of oscillation frequency characteristics in open cavity flow excitation

Abstract

During the cruise phase, complex flow phenomena such as shock waves, vortices, turbulent boundary layers, and their mutual interference will occur, generating intense unsteady aerodynamic excitation and pressure pulsations around the aircraft and its components. This can induce high-intensity acoustic-vibration loads, deteriorating the working environment of the aircraft. Severe structural vibrations may even affect the normal operation of onboard instruments and meters, and endanger the safety of local structures. This paper conducts a numerical simulation study on the hollow configurations of civil aircraft with a length-depth ratio of 2 to 5. Two sets of grids of different thicknesses are used to calculate the frequency characteristics of the flow-induced oscillation of the hollows. Typical high-speed wind tunnel tests were carried out on the hollows, and the static pressure data and pulsating pressure response data at each measurement point were analyzed. The flow-induced oscillation phenomenon inside the hollows was captured, and the main characteristic frequencies were obtained. The frequency error of the corrected analysis method is within 5%, and the amplitude error is within 7 dB.