EXPERIMENTAL STUDY ON CORRELATIONS WITH FLOW PATTERN AND AEROACOUSTIC CHARACTERS FOR LOW SPEED CAVITY

Flow oscillation can be produced when the flow pass over open cavities, which would cause multiplied increase of component drag, the structure vibration and fatigue damage. The mechanisms of noise producing in cavity must be understood and identified accurately. In this paper, the experimental study of flow pattern and basic aeroacoustic characteristics for rectangle cavities cleaning was carried out in low-turbulenc e wind tunnel with the measurement of static pressure distribution on cavity bottom and sound pressure detection on typical measuring stations. The average static pressure distribution on various cavity bottoms and noise spectrum on typical stations arranged on bottoms and back wall of cavities have been collected and analyzed. The results showed that the shear layer’s instability is different under the same flow condition, namely, the flow oscillations and instabilities in cavity weakened with the cavity ratio of length to depth increased. The shear layer consists of vortex shedding from leading edge to downstream, impacts the back wall that inspires new vortex shedding and produce new sound source. The work in this paper provides the foundation for further noise suppression control study.