Numerical investigation on the unsteady cavitation shedding dynamics over a hydrofoil in thermo-sensitive fluid
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2018 Elsevier Ltd Cavitation shedding is of a great practical interest since the unsteady flow features can induce significant fluctuations around the body where cavitation occurs, especially in thermo-sensitive fluid. The present paper numerically studies the unsteady cavitating flows over a NACA0015 hydrofoil in thermo-sensitive fluid of fluoroketone with special emphasis on the cavitation shedding dynamics. Comparisons between numerical predictions and available experimental data are performed to validate the numerical framework and help us further understand the physical feature. The results show that the predicted cavity evolution and pressure distribution are in good agreement with the experimental data. It is observed that the cavitating flows over the hydrofoil undergo more complex unsteady periodic evolution, including the cavity formation, growth, break-off, collapse and shedding. Two propagation patterns of the re-entrant flow appear along the chordwise direction and the spanwise direction, which are responsible for the unsteady cavity evolution. Note that the temperature distribution around the hydrofoil is closely related to the cavity evolution. The temperature around the hydrofoil undergoes a strong evolution that is contributed by the local evaporation and condensation processes. Meanwhile, the thermal effects on cavitating flows are associated with temperature-dependent physical properties of the fluid media. Interestingly, compared to the isothermal cavitation, thermal effects suppress the intensity of cavitation and show a potential to reduce the pressure pulsation peak. Furthermore, there is a strong interaction between the complex vortex structure and cavitation evolution. In one typical cycle, the rotation effect and the shear effect co-dominate the cavity growth, break-off and shedding of the unsteady cavitating flows.
