Investigation on key aerodynamic and aeroacoustic problems of internal weapons bay

An experimental investigation was conducted in a high speed wind tunnel to explore key aerodynamic and aeroacoustic problems of internal weapons bay. Steady pressure measurement, fluctuation pressure measurement and grid measurement were applied to obtain detailed characteristics of static pressure, fluctuating pressure and internal weapon aerodynamic in this experiment. Results indicated that flow types of internal weapons bay can be defined by the static pressure distributions on its floor. Aeroacoustic environment for open cavity flow is much worse than closed cavity flow, and the maximum sound pressure level can reach up to more than 170dB. Several tones of different modes can be found in the internal weapons bay sound pressure spectra. Internal weapon may occur large positive pitching moment during separating from the bay, and positive pitching moment is harmful to safe separation between fighter plane and weapons. Results also indicated that mass-injection at the fore-edge of internal weapons bay can reduce static pressure gradient, suppress the intensity of noise and improve internal weapon's aerodynamic separation characteristics.