Noise generated by ventilated supercavities

The control of ventilated supercavity pulsation and noise

“…The amplitude of the forcing function, F o , was estimated to be 11.63 m 2 /sec 2 . This assumes that the fluctuating external cavity pressure amplitude is equal to the fluctuating internal pressure amplitude, which was typically 3.5 kPa for a pulsating cavity with an average radius of 2.3 cm inside of the 0.305 m diameter water tunnel ( Skidmore et al, 2015a ). Modulation strength values range from 0.10 to 0.25, which correspond to oscillations about the constant ventilation rate resonance frequency from 4.9% to 11.8%, respectively.…”

“…The "pinch off" or terminus of the cavity is considered to be the point where the local cavity diameter becomes less than that of the cavitator ( Paryshev, 2003 ). This process results in a strong monopole sound source ( Skidmore et al, 2015a;Pierce, 1989 ). A typical pulsating supercavity generated in the ARL Penn State 0.305 m diameter water tunnel is shown in Fig.…”

“…It is characterized by the presence of traveling surface waves on the cavity interface that cause the cavity volume to change periodically and, in correspondence, the cavity pressure to change. The oscillating cavity pressure sets the air/water interface into an oscillating trajectory as it separates from the edge of the cavitator (viewed relative to the cavitator) ( Skidmore et al, 2015a ). The oscillating interface advects downstream to the cavity terminus.…”

“…(1) was used to successfully predict the resonance/pulsation frequencies of ventilated supercavities ( Skidmore et al, 2015a ). Pulsation occurs when the interface instability induced wave frequency is equal to the ventilated supercavity gas/water system resonance frequency ( Song, 1961 ).…”

Numerical investigation on cavitation flow of hydrofoil and its flow noise with emphasis on turbulence models

“…Park et al (2009) proposed noisesource localization methods for conducting water-tunnel experiments using matched field processing and source-strength estimation techniques, which could be applied to propeller noise experiments under shallow water conditions. Skidmore et al (2015Skidmore et al ( , 2016) studied ventilated super-cavitation and its hydro-acoustic noise. They measured the hydrodynamic pressure both inside and outside the artificial cavities and analyzed the hydro-acoustic characteristics based on the types of cavitation.…”