A Numerical Investigation of Free and Forced Transition Effects on Hydrofoil Characteristics

Abstract

The numerical study investigates the transition effects on the lift and drag char- acteristics of a hydrofoil which represents a section of a yacht’s keel. Two types of turbulence stimulators are examined: rectangular trip wires and strips which are properly represented through boundary conditions. A new calculation technique models free transition, based on empirical data. The numerical method solves the RANS equations in orthogonal curvilinear coordinates by the finite volume approach and the k-ε-SST model has been employed to account for turbulence effects. Computations at two Reynolds numbers and three incidence angles assess the influence of the type and the location of the turbulence stimulator with respect to lift and drag as well as to the local skin friction and pressure coefficients. Full-scale calculations show how the Reynolds scaling associated with free transition may influence the lift and drag characteristics of the hydrofoil.