Super-Cavitating Profiles for Ultra High Speed Hydrofoils: a Hybrid CFD Design Approach

The paper presents the main results obtained from a systematic assessment about the current possibility to simulate hydrodynamic characteristics of super-cavitating hydrofoils with state of the art CFD methods. First a systematic validation of the finite volume RANSE solver with volume of fluid method for the multiphase flow and a simple Rayleigh-Plesset model for bubble dynamics. Sensitivity of the solver to various parameters which affect the cavitation model is verified as well as the integration time-step, the number of inner iterations, which influence the unsteady calculations. The final best configurations of the CFD model are used for its validation against experimental results on a reference two terms super-cavitating profile at a typical design angle of attack and for the complete range of cavitation indexes. After this preliminary study, the paper continues with the verification of the performance in case of different super-cavitating hydrofoils with two/three and five terms face shapes, designed using a classical asymptotic theory for the face and the back shapes chosen on the basis of cavity shapes predicted RANSE simulations. The RANSE method proves to be effective to design the hydrofoil back side for finite cavitation numbers and to assess its performance of for the next 3D hydrofoil design.