Abstract
The present work focuses on the comparison of the numerical simulation of sheet/cloud cavitation with the Reynolds Average Navier-Stokes and Large Eddy Simulation(RANS and LES) methods around NACA0012 hydrofoil in water flow. Three kinds of turbulence models—SST k-ω, modified SST k-ω, and Smagorinsky’s model—were used in this paper. The unstable sheet cavity and periodic shedding of the sheet/cloud cavitation were predicted, and the simulation results, namelycavitation shape, shedding frequency, and the lift and the drag coefficients of those three turbulence models, were analyzed and compared with each other. The numerical results above were basically in accordance with experimental ones. It was found that the modified SST k-ω and Smagorinsky turbulence models performed better in the aspects of cavitation shape, shedding frequency, and capturing the unsteady cavitation vortex cluster in the developing and shedding period of the cavitation at the cavitation number σ = 0.8. At a small angle of attack, the modified SST k-ω model was more accurate and practical than the other two models. However, at a large angle of attack, the Smagorinsky model of the LES method was able to give specific information in the cavitation flow field, which RANS method could not give. Further study showed that the vortex structure of the wing is the main cause of cavitation shedding.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Zhang et al [11] and Huang et al [12] studied the dynamic mechanism of cavitation, and the results demonstrated that the re-entrant flow is the main factor for the flow structure and the shedding pattern of cavitation
Cavitation suppression was studied by using the Liutex vorticity control method [24], and the results showed that the influence on the flow field can relieve the pressure reduction area and suppress cavitation
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The method cannot provide the details of the re-entrant jet, which includes the important flow characteristics of periodic breaking, cavitation shedding, and the collapse of the sheet cavity It is very expensive and time-consuming to carry out experimental research on the cavitation structure of a real marine propeller or even the complex geometry of a real pump, and it is almost impossible in some cases. Zhang [26] realized a new multiphase model that contains the advantage of the interface capture method and particle tracking method; the numerical output showed that the bubbles of various scales can be calculated at the same time, and this achievement is important in a multiphase cavitation study Some researchers such as Schnerr and Sauer [27] have improved the CFD cavitation models. Considering the accuracy of numerical analysis results and the complexity of calculation, the modified SST k-ω model has advantages in cavitation simulation at a small angle of attack
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