To investigate the evolution of supercavity geometry and the unsteady characteristics of the supercavitation flow from the initial generation to full development. A three-dimensional numerical model with the inhomogeneous multiphase model and SST $k-\omega$ turbulence model was established. The numerical model was validated by experimental results. The ventilated supercavitation flow was performed under the different gas entrainment coefficients and Froude numbers. The results show that the initial supercavity closure mode is the re-entrant jet, then the closure mode changes to the twin-vortex induced by the gravitational effect. For the fully developed twin-vortex supercavity, a flow structure with gas recirculation exists inside the supercavity, which includes the reverse flow region and downstream flow region. Compared to the supercavity with the twin-vortex closure mode, the increment in the supercavity dimension with the re-entrant jet closure mode increases drastically, and the oscillation characteristic of internal pressure increases, leading to the significant supercavity deformation and gas shedding. The difference of the supercavity dimension is revealed by analyzing the gas leakage behavior. Further, a theoretical model describing the strength of re-entrant jet is established to reveal the transition mechanism of the supercavity closure mode and analyze the unsteady flow characteristics during the supercavity development.

研究超空泡几何结构的演化和超空泡流动从初始产生到全面发展的非定常特性。具有非均匀多相模型和 SST 的三维数值模型$k-\omega$湍流模型建立。通过实验结果验证了数值模型。在不同的气体夹带系数和弗劳德数下进行通风超空泡流动。结果表明，初始超空腔闭合模式为重入射流，随后闭合模式转变为受引力作用引起的双涡。对于充分发展的双涡超腔，超腔内部存在气体再循环的流动结构，包括逆流区和顺流区。与双涡闭合模式的超空腔相比，重入射流闭合模式的超空腔尺寸增量大幅增加，内压振荡特性增加，导致显着的超空腔变形和气体脱落。通过分析气体泄漏行为揭示了超腔尺寸的差异。此外，建立了描述重入射流强度的理论模型，以揭示超空腔闭合模式的转变机制，并分析超空腔发展过程中的非定常流动特性。