Aero-Acoustic Experimental Investigation Of The Cavity Flow Fields In High Speed Wind Tunnel

Internal weapon carriage systems will be a new trend for future aircraft program, which can reduce not only the total vehicle drag but also the radar signatures. However, when cavity expose to freestream flow, intense aeroacoustic environment can develop. High acoustic loads can significantly reduce the life of aero-structures in the cavity and damage sensitive electronic components.Based on steady pressure distributions in different cavities, four flow types were defined (open flow, transitional-open flow, transitional-closed flow, closed cavity flow). At the same time, static pressure distributions and aeroacoustic environment were obtained in cavities with different parameters and mach numbers.The results of tests show that a). the cavity flow types have great correction with the length-to-depth of cavities and free flow mach numbers. And there are great difference in static pressure distributions and aeroacoustic environment with different flow types of cavities.b). For closed cavity flow, the flow separates at the forward face of the cavity, reattaches at some point along the cavity floor, and separates again before reaching the rear cavity wall. Two distinct separation regions were created. It was dangerous for internal weapons carriage. However, for open cavity flow, static pressure distributions in cavities are nearly uniform , which are desirable for safe store separation .c) There are very great sound pressure levels in both open cavity flow and closed cavity flow. intense aeroacoustic environment in the cavity with loads as high as 172 dB.d) For open cavity flow, the cavity tones occur almost at the same frequencies regardless of the transducer locations.High acoustic loads can significantly reduce the life of aero-structures in the cavity and can damage sensitive electronic components. However, for closed cavity flow, the high-intensity acoustic tones disappear.