Investigations on effects of free-stream mach numerber on flow and aeroacoustic characteristics in cavity

This paper presents effects of free-stream compressibility (Ma) on aeroacoustic characteristics inside different flow-type cavity with length-depth ratios (L/D) of 8, 12 and 15 at Mach numbers of 0.6, 0.9, 1.2, 1.5 and 1.8. The results indicate that free-stream compressibility (Ma) is a key parameter influencing flow type and aeroacoustic characteristics in the cavity. Increase in free-stream compressibility leads to increase in sound pressure level (SPL) and SPL at different discredited frequencies for measurement positions in the cavity. It also causes bad pressure fluctuating and intense aerodynamic noise, which has bad influence on self-structure security of the cavity and stored something.