Numerical Study on the Interaction Characteristics between Attached Cavitation and Velocity Boundary Layer under Different Working Conditions

Abstract

Attached cavitation often occurs on the blade surface of hydraulic machinery, negatively affecting its performance. The SST k-ω turbulence model and SS cavitation model are employed to calculate the attached cavitation on the surface of the NACA0015 hydrofoil to explore the interaction between attached cavitation and the velocity boundary layer. The findings are systematically analyzed from four aspects: flow field characteristics, vortex dynamics, boundary layer characteristics, and energy loss. The results indicated that the spanwise effect of the surface flow field of the hydrofoil is more pronounced at low cavitation numbers. From the perspective of vortex dynamics, each vortex transport term is sensitive to the change in cavitation number, and the trend of each vortex transport term varies with the change in cavitation number. The inverse pressure gradient region of the velocity boundary layer is primarily distributed in the tail of the attached cavity, significantly affecting the formation of the phase interface at the tail of the cavity and the cavity shedding. The energy loss on the suction surface of the hydrofoil is mainly concentrated in the velocity boundary layer, with PL1 and PL3 being the primary ones. When the interface of the attached cavity phase overlaps with the velocity boundary layer, it promotes the energy loss of the local fluid. When the attached cavity completely covers the velocity boundary layer, the energy loss in the boundary layer is significantly reduced.

Keywords

• attached cavitation
• velocity boundary layer
• vortex dynamics
• energy loss
• cfd