Fluid–body interactions on a flexible three-dimensional composite hydrofoil

This study presents an experimental investigation of the flow around a three-dimensional flexible hydrofoil at Reynolds numbers between 3.6× 10⁵ 3.6 × 10 5 and 7.2× 10⁵ 7.2 × 10 5 and angles of attack from -8∘ - 8 ∘ to 8∘ 8 ∘ . Time-resolved particle image velocimetry, force-balance measurements, deflection, and hydrophone data are used to analyze the hydrodynamic forces and wake dynamics in both the time and frequency domains. The results are compared with those of a rigid reference hydrofoil. Under specific flow conditions, a strong coupling is observed between the fluid motion, hydrodynamic loading, and the hydrofoil’s natural vibration modes. This lock-in behavior shows a pronounced dependence on the angle of attack, resulting in a significant redistribution of turbulent kinetic energy in the wake and enhanced coherence in the trailing-edge vorticity.