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  • Transient cavitating flow s...
    Li, Zehao; Qian, Zhongdong; Ji, Bin

    Applied Mathematical Modelling, September 2020, 2020-09-00, 20200901, Volume: 85
    Journal Article

    •Cavitation dynamic behaviors of the hydrofoil with whalelike leading-edge protuberances are simulated.•The k-ω SST model with local compressibility correction for turbulent viscosity is implemented in OpenFOAM.•Interactions between cavitation and streamwise vortex pairs are discussed.•Influence factors of monopole and dipole noise in cavitating flow are obtained from Lighthill's acoustic analogy theory.•Time domain characteristics of monopole and dipole noise in cavitating flow are discussed. In this paper, the open source software OpenFOAM is used to perform a numerical investigation of the cavitating flow around a modified NACA634-021 hydrofoil with bioinspired, wavy leading edge, with particular emphasis on study of the interactions between the cavitation and the streamwise vortices and the far-field radiation noise. A modified k-ω shear-stress transport (SST) model coupled with the Schnerr-Sauer cavitation model and the Ffowcs Williams-Hawkings (FW-H) acoustic analogy approach are introduced to the simulation. The transient cavitation structure and the streamwise vortices are captured well and the results show significant interactions between the cavitation and the streamwise vortices. Cavitation can promote fragmentation of the streamwise vortices, while the streamwise vortices cause cavitation inception to occur earlier and bind the cavitation within the trough region by changing the pressure distribution on the hydrofoil. The transformation of the FW-H equation's solution indicates that the monopole noise is directly related to the cavitation volume acceleration and the dipole noise is related to the mechanical force of the hydrofoil on fluids and the rate at which this force changes. The collapse of cavitation cloud and the collision of the re-entrant jet and main flow will cause violent fluctuation of the mechanical force thus produce instantaneous extreme dipole noise values, while the monopole noise is relatively strong in the cavitation collapse stage due to significant cavitation volume acceleration. The time domain hydroacoustic characteristics are similar for the modified hydrofoil and the baseline hydrofoil.