Multi-Body Unsteady Aerodynamics in 2D Applied to a Vertical-Axis Wind Turbine Using a Vortex Method

Vertical axis wind turbines (VAWT) have many advantages over traditional Horizontal axis wind turbines (HAWT). One of the more severe problem of VAWTs are the complicated aerodynamic behavior inherent in the concept. In contrast to HAWTs the blades experience varying angle of attack during its orbital motion. The unsteady flow leads to unsteady loads, and hence, to increased risk for problems with fatigue. A tool for aerodynamic analysis of vertical axis wind turbines has been developed. The model, a Discrete vortex method, relies on conformal maps to simplify the task to finding the flow around cylinders. After the simplified problem has been solved with Kutta condition, using the Fast Fourier transform, the solution is transformed back to the original geometry yielding the flow about the turbine. The program can be used for quick predictions of the aerodynamic blade loads for different turbines allowing the method to be validated by comparing the predictions to experimental data from real vertical axis wind turbines. The agreement with experiment is good.