The structures of unsteady cavitation shedding flow around an axisymmetric body with a blunt headform
The objective of this paper is to investigate the cavity shedding dynamics in unsteady cavitating flows around an axisymmetric body with a blunt headform. A high-speed video camera is used to record the cavity evolution process. The numerical simulations are performed based on the homogenous method coupled with a modified PANS (Partially-averaged Navier-Stokes) turbulence model and Zwart cavitation model. The results show that the predicted time-evolution process of cavity agree fairly well with the corresponding experimental data for two different cavitation numbers (σ = 0.7 and σ = 0.6 ). Compared to that of σ = 0.6, the cavity shedding behavior of σ = 0.7 presents more fluctuations and instabilities. To elucidate the different shedding structures, the Lagrangian coherent structures (LCS) and particle trajectory methods are also utilized here. It is found that the particle tracers respectively demonstrate the cavity shedding behaviors of conjunction at σ = 0.6 and rolling up at σ = 0.7. Moreover, the LCS distributions vary with the timeevolution of vortex structures. The particle trajectories can illustrate the upstream and downstream vortex structures connect together at σ = 0.6 but separate at σ = 0.7, which highly consistent with the cavity shedding behaviors.
KeywordsCavity shedding dynamics Vortex Lagrangian particle trajectory Axisymmetric body
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