Fluid Forces on a Hydrofoil for Kitefoil and Windfoil Boards: Experimental Investigation on Their Dependence on the Froude Number Based on Submergence

Abstract

Races using kitefoil and windfoil surfboards have been in the Olympic Games for the first time in Paris 2024, signalling their relevance in sailing sports. However, the dynamics of these devices is yet not well understood, in particular the influence on the hydrodynamic forces and moments of the distance of the foil to the free surface. Considering this, the present paper documents an experimental investigation in which forces and torque produced, under uniform flow, by a full-scale state-of-the-art hydrofoil (suitable both for kitesurf and windsurf) were measured. A range of velocities, angles of attack, and submergences were tested, leading to Froude numbers based on submergence with maximum values around five, a typical range in actual sailing conditions. From these tests, formulae for the hydrodynamic coefficients have been proposed. They can be used for developing Velocity Prediction Programs (VPP) for this kind of craft, a necessary tool to plan racing configurations and to analyze their racing performance. With the aim of making the experimental data useful for benchmarking numerical models and for future research on related topics such as foil ventilation and transition to turbulence, the specimen’s 3D file is provided as supplementary material to this paper.

Keywords

Hydrofoil / Kitefoil / Windfoil / Velocity prediction programs / Lift coefficient / Drag coefficient

RIGHTS & PERMISSIONS

Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature