Optimization of active blade pitching of a vertical axis wind turbine using analytical and CFD based metamodel

This study optimizes the active blade pitching (ABP) motion of a vertical axis wind turbine (VAWT) to increase its power output over a wide range of tip speed ratios (TSRs). The study begins by developing a simplified analytical model to compute the torque output of the VAWT as a function of its ABP. The analytical model is used to generate a preliminary optimal ABP at a single TSR. Next, computational fluid dynamics simulations are employed to develop metamodels of the response of the VAWT. These metamodels are used to determine the final optimal ABP. The optimization procedure is then repeated for different TSRs to determine an optimal ABP as a function of the TSR. The power outputs for the ABP-driven VAWT are compared with those of a fixed blade VAWT at different TSRs. The results indicate a 13% increase in the maximum power output of the VAWT compared to an optimal fixed pitch strategy. The torque outputs of the ABP-driven VAWT are then compared with those of a fixed blade VAWT at low TSRs. The results indicate that ABP would significantly improve the self-starting capability of VAWTs.