Numerical prediction of hydro-acoustics signature of NACA foils for tidal turbines

Abstract

Tidal power is one of the renewable energy sources. The tides produced in the water is used to drive the blade rotation of a tidal turbine for energy conversion. However, the blade rotation produces noises over 10–150 kHz that affect underwater mammals. In this wok, numerical simulations are conducted to predict the hydro-acoustics signature of different NACA foils, which could be used for tidal turbine blades. Finite volume and Ffowcs-WilliamsHawking’s method are used to predict the fluid dynamics and acoustics signatures. We first study the effect of thickness to chord ratio (Tb/cb = 0.1, 0.13 and 0.19) on the noise generation from three different NACA foils (i.e., NACA0012, 0018, and 2410). Hydrodynamic data of these three foils are used for validation of its hydro-acoustics signature. Hydro-acoustics data are acquitted over the propagation distance from 50 m to 2.6 km at different angular positions and at various angles of attack (AOA) (AOA = 0°, 9°, and 15°). To shed lights on the sound generation mechanism, the NACA 2410 foil with vortex generator-produced perturbations is chosen as a case study. Comparison is then made between the prediction and the acoustic data of an actual foil.