Large Eddy Simulation of Sheet-to-Cloud Cavitation Dynamics over a Hydrofoil under Erosive Condition at very High Reynolds Number: Flow and Spectral Analysis

Cavitation on propulsors and lifting surfaces is undesirable and can cause erosion. At high Reynolds numbers and cavitation numbers that lead to sheet-to-cloud cavitation, the interactions between the cavity and the hydrofoil surface become dynamic and significantly more complex. The cavity generates highly turbulent vortex structures that interact with other vortices formed by flow separation near the trailing edge. To study these interactions, incompressible LES, combined with Schnerr-Sauer cavitation model, is employed to complement the cavitation erosion experiment at Re=50 million conducted at the U.S. Navy's William B. Morgan Large Cavitation Channel (LCC). A simulation, spanning the full width of the LCC test section with wall boundary conditions, is conducted at the most erosive condition, where the cavity length is approximately half the chord. Additionally, three cases at different cavitation numbers, using a span width of 5% of the chord with cyclic boundary conditions, are simulated. All simulations accurately capture the cavity cycle and flow dynamics, aligning with the LCC experimental measurements. Vorticity transport analysis shows vortex stretching, dilatation, and baroclinic torque are present, with stretching term being dominant. Spectral analysis reveals a strong peak at St=0.45 within the cavity region on the pressure side and a peak at St=10 near the trailing edge. Moreover, SPOD identifies dominant cloud shedding modes and their correlation with wake vortices.