Aerodynamics of static and dynamic stall - An experimental study

Most aerofoils are operated at high angles of attack to maximise aerodynamic performance where they are prone to separation and stall, especially when they are operating under varied conditions. This is especially true for wind turbines, propellers and other rotating machinery. In these situations, the flow mechanisms and the noise generating features are substantially different compared to lower angles of attack. Our knowledge and understanding of the mechanisms as well as our ability to predict these aerodynamic phenomena and noise sources is limited. In this project, the goal is to carry out detailed near-field flow experiments as well as far-field noise measurements to develop new understanding of the aerodynamics and aeroacoustics in the presence of separation and stall. Three-dimensional Particle Image Velocimetry will be performed over a foil in a water channel to elucidate the aerodynamic mechanisms. The 3D data will be combined with new data assimilation strategies to determine the full-field pressure. This pressure field will be used to determine relationship between velocity and pressure across the flow and also used to predict the far-field noise generated by the foil. This prediction can be compared against experiments carried out in an anechoic wind tunnel where far-field noise can be measured directly. Ultimately, the high-fidelity data generated in this project will will then be used to identify flow mechanisms that contribute to the different aerodynamic force and noise sources at high angles of attack.