Tests for pressure fluctuating characteristics around a ventilated underwater vehicle

The cloud type cavity around a ventilated underwater vehicle was investigated in water tunnel. The test was conducted to study pressure fluctuating characteristics of the vehicle surface under different cavitation numbers. In order to analyze the cavity stability around the vehicle in water flow, a dynamic force measurement system was used to measure surface pressures of the ventilated underwater vehicle under different cavitation numbers, the recorded pressure signals were analyzed in frequency domain to get their frequency spectra. The frequency domain features of the pressure fluctuating characteristics were obtained. The results showed that cavity shapes and pressure fluctuating features with the variation of cavitation number have obvious unsteady characteristics, the states of cavity flow field are highly correlated with feature frequencies of pressure fluctuating; for the ventilated underwater vehicle, its surface pressure fluctuating is caused due to large size cavies' periodically shedding; the mean pressure peak value of the vehicle surface increases with decrease in cavitation number and the surface pressure fluctuation is small after cavity shedding.