Scale dependency of pressure distribution, lift, and vortex shedding of a hydrofoil*

Full-scale control surfaces and propulsors are subject to cavitation erosion patterns that are not always related to expectations at model scales. Turbulent flow at the trailing edge of the surface results in uneven pressure distribution in the near wake area of the hydrofoil. The behavior of turbulent flow in the boundary layer regarding transition and separation as a function of Reynolds number must be properly captured to understand pressure distribution and resultant forces, such as lift and drag, to aid in full-scale experiment design selection. A series of large-eddy simulations using the curvilinear immersed boundary method are undertaken at a range of Reynolds numbers, angles of attack, and cavitation numbers. Two trailing-edge bevel angles of the hydrofoil are considered due to the geometry-dependence of the near wake. Turbulent flow at the trailing edge results in uneven pressure distribution in the near wake area of the hydrofoil. The lift forces and pressure distribution around the hydrofoil are used to choose design parameters for the model and full-scale hydrofoils to be experimentally tested. Understanding the boundary layer and near wake dynamics that produce unsteady pressure distributions of the surface at a range of Reynolds numbers is one of the first steps in assessing the scale dependency of cavitation erosion.