Nucleation dynamics in cloud cavitation

Nuclei dynamics associated with cloud cavitation about a 2D NACA16-029 hydrofoil are investigated experimentally in a cavitation tunnel. Tests were made at a cavitation number of 0.5 and Reynolds number of 1.2 × 10⁶. Nuclei dynamics were investigated using high speed photography at a frame rate of 12 kHz. Nuclei are generated during each cavity shedding cycle due to cavity breakup from shock wave phenomena. These nuclei may undergo immediate activation or transport upstream due to pressure gradients, local recirculation, and jetting. Some nuclei remain upstream of the cavity leading edge over multiple cycles. Several phenomena influence this behaviour, including cyclical variation of boundary layer properties with each shedding cycle. A major conclusion of the work is that these nuclei are produced in a self-sustaining manner from near surface, small scale, interfacial or viscous phenomena rather than from surface nuclei.