Suppression of tip vortex cavitation of elliptical hydrofoil based on active water injection methods

  Objective  As tip vortex cavitation (TVC) causes noise radiation and vibration, it is necessary to understand how to predict and control its development, and understand its mechanism in order to suppress it, especially in the field of ship propellers and other rotating machinery.

  Method  Focusing on an elliptical hydrofoil with an NACA 0012 cross-section, this study uses the Improved Delayed Detached Eddy Simulation (IDDES) turbulence modeling method and Schnerr-Sauer cavitation model to simulate TVC on the hydrofoil and analyze its behavioral characteristics under wet flow and cavitation flow conditions. After that, two active water injection methods, side injection and top injection, are introduced into the simulation to reduce and suppress cavitation inception respectively.

  Results  Taking the cavity volume of the tip vortex as the criterion for cavitation suppression, compared with the condition without water injection, top injection can inhibit cavitation by 8.09%. Moreover, under the condition of side injection, the effect of the injecting flow on the cavitation is more obvious, reaching 10.47%. The results show that both top and side injection can effectively suppress TVC.

  Conclusion  Top injection can change the flow direction and speed of the tip vortex incident flow, and increase the dissipation term of the turbulent kinetic energy; while in side injection, the energy it carries acts directly on the vortex structure of the hydrofoil, destroying the vortex and greatly suppressing the generation of cavitation.