Effect of ventilation on supercavitation dynamics and hydroacoustic characteristics: A numerical comparison with unventilated conditions

This numerical study examines the hydrodynamic and hydroacoustic behavior of an underwater vehicle under supercavitating conditions, both with and without ventilation. A body measuring 2100 mm in length and 128 mm in diameter operates in a 2300 mm-long domain. A water inflow of 10 ms and gas injection of 0.3 kgs create ventilated supercavitation. Without ventilation, the drag coefficient is about 0.7, while strong vortices and flow separations generate intense, low-frequency noise. At 10 m and 90∘, the sound pressure level (SPL) peaks near 110 dB below 50 Hz. At 100 m, this attenuates to 60–80 dB. Ventilation reduces drag to ∼0.3, but increases low-frequency SPL at 10 m and 90∘ up to 135 dB (2–50 Hz). Ventilation also broadens the noise spectrum, with the SPL at 100 m still around 80–90 dB below 50 Hz, surpassing the unventilated case. At 1000 m, SPLs for both conditions drop to about 20–40 dB at high frequencies, demonstrating distance-related attenuation. Monopole sources dominate at low frequencies, with up to 110 dB near-field SPL in the unventilated case, while dipole sources significantly influence mid-frequency ranges (50–300 Hz). Under ventilation, the monopole remains strong at low frequencies (about 80–90 dB at 100 m), but dipole contributions weaken over distance. Overall, while ventilation reduces drag, it intensifies and broadens the acoustic field at near-field locations, underscoring the complex tradeoffs between drag reduction and noise emission. These findings highlight the importance of careful ventilation strategies to manage noise and performance.