Dynamic hysteresis process in tip vortex cavitation

In this Letter, experiments are conducted on tip vortex cavitation (TVC) over a stationary elliptical hydrofoil with the cross section of NACA (National Advisory Committee for Aeronautics) 66 2 - 415 in a water tunnel. The state of TVC at various cavitation numbers, inflow velocities, and angles of attack is tested. Several macroscopic phase transition processes of TVC are discovered within the hysteresis loop with the operating conditions unchanged, and these new phenomena are defined as the dynamic hysteresis (DH) processes. In addition, the noise characteristics are analyzed to further study the DH. Similar noise spectra are obtained for the DH processes under different working conditions, with a major peak of the same frequency regardless of whether vortex singing occurs or not.