Numerical Investigation of the Post-stall Flow Patterns over a NACA 0021 Hydrofoil with Sinusoidal Leading Edge

Abstract

As passive flow-control devices disrupting flow separation, leading-edge protuberances can provide superior hydrodynamic performance to hydrofoils at high angles of attack. Most experimental and numerical investigations carried out for low Reynolds number conditions have related the relative improvements observed post-stall to “bi-periodic” flow structures, developing over tubercles pairs. In this study, a numerical approach is employed to show the emergence of higher-order patterns in the flow over a stalling NACA 0021 hydrofoil with sinusoidal leading edge. The effect of the number of sinusoidal tubercles defining the leading edge of the hydrofoil model on the prediction of “bi-periodic” or “tri-periodic” flow structures is particularly analyzed to interpret the uncertainty found on the resulting hydrodynamic performance.