Abstract:To improve the resistance cavitation performance of hydraulic machinery, the mechanism of unsteady cloud cavitation shedding around the NACA0015 hydrofoil was studied by combining numerical simulation and experimental method. The cavitation fluctuation caused by the unsteady cavitation structure on the hydrofoil surface under different cavitation stages was analyzed, and the main reasons for pressure fluctuation during the unsteady process of cavitation were discussed. The results demonstrated that the FBDCM turbulence model could accurately simulate the unsteady process of periodic shedding of cavitation on hydrofoil surface. Under the condition of the attack angle was 8° and the cavitation number was 1.25,the unsteady process of cavitation evolution can be divided into three stages: formation and growth of attached cavitations, shedding of the attached cavitation and formation of cloud cavitation, the stage of development and collapse of cloud cavitation. At the end of the second stage, the cavitation volume fraction increases to the maximum during the period. In the third stage, the pressure level on the hydrofoil surface gradually rises due to the collapse of the cavitation shedding pattern on the hydrofoil surface, and the main reason for the cavitation shedding was the re-entrant jet flow.