Multiscale cavitation dynamics and pressure pulsation of a propeller under nonuniform wake

Cavitation around marine propellers is a multiscale, multiphase phenomenon that significantly affects hydrodynamic performance and structural response through pressure pulsations. This study experimentally investigates the dynamic relationship between multiscale cavitation structures and their corresponding pressure responses under nonuniform inflow conditions. A multifield synchronous measurement system was employed to capture the evolution of cavitation morphologies along with pressure signals. In addition, a digital inline holography (DIH) system was introduced to quantify the spatial and statistical characteristics of microbubbles in the cloud clusters. The experiments reveal a sequence of cavitation regime transitions, progressing from noncavitating flow to tip vortex cavitation, to the coexistence of sheet and tip vortex cavitation, followed by the onset of cloud cavitation, and ultimately the collapse of vortex structures. Each regime exhibits distinct pressure spectral signatures, with the cloud bubble cluster regime displaying the strongest multiscale interactions. Within this regime, cavitation evolves through four consecutive stages: inception, initial vortex shedding, secondary shedding, and final decomposition. Phase-resolved DIH measurements demonstrate that microbubble size distributions follow an exponential probability density function, exhibiting strong phase-locking and interrevolution consistency. An equivalent single bubble model was developed to estimate pressure pulsations based on reconstructed bubble statistics, accurately reproducing midand high-frequency spectral components associated with bubble collapse. These results offer insights into the multiscale mechanisms of cavitation-induced pressure generation in marine propulsors.