Experimental modelling of steady hydrofoil fluid-structure interaction

Static hydroelastic behaviour of two geometrically identical flexible metal hydrofoils of Aluminium and Stainless Steel are investigated in a water tunnel. The hydrofoils are of unswept trapezoidal planform, aspect ratio 3.33, NACA 0009 section and were oriented vertically in the water tunnel mounted on a force balance through the test section ceiling. Forces and deflections were measured at several chord-based Reynolds numbers up to 10⁶ and incidences beyond stall. Hysteresis and the effect of test section ceiling boundary layer thickness were investigated. Prestall forces where observed to be Reynolds number dependent for low values but became independent at 0.8 × 10⁶ and greater. Tip deflections up to 4.5% of span were measured for the Aluminium hydrofoil. Forces and deflections were observed to be stable up to stall. Non-dimensional tip deflections of both hydrofoils were found to be independent of incidence. Forces for both hydrofoils compare closely for all incidences and Reynolds numbers tested, within uncertainties, showing these to be independent of deformation.