Wind Tunnel and CFD Studies for Determining Forces on a Hydrofoil

Abstract

The subject of this paper is the investigation of the hydrodynamic properties of a wing combination of a hydrofoil system as a lift generating element of a foil board. The hydrofoil system consists of a main and a rear wing, which are connected by means of fuselage construction. This wing combination is attached below a foil board using a mast. As the forward motion accelerates, e.g., pumping, kite, sail, or electric motor, the board is gradually lifted out of the water and glides at a higher velocity due to the significantly reduced drag. The investigations are carried out using an existing hydrofoil system in a Göttingen-type wind tunnel. The wind tunnel tests are used to determine the forces and moments to describe the lift and drag behavior of the hydrofoil system. Numerical analyses were performed for the tests in wind tunnel and the results of the calculations were validated with the experimental results in air. In the following numerical simulations, the fluid air was replaced by water in order to obtain realistic data on the flow around a hydrofoil system. Similarity conditions between water and air flows were applied to define the relationship between different fluids and obtain realistic predictions of behavior at higher Reynolds numbers.