Study on aerodynamic performance of a combined vertical axis wind turbine based on blade element momentum theorem

The vertical axis wind turbine is mainly divided into lift type and drag type. The lift-type wind turbine has high-power coefficient, but it is difficult to start. The drag-type wind turbine is easy to start, but the power coefficient is low. Combined with the advantages of the two, a combined wind turbine with the lift blade and the drag blade is designed in this paper, which is expected to obtain higher power coefficient and better starting ability. For the combined wind turbine, based on the blade element momentum theorem, the analytical model of multiple-disk-multiple-streamtube is established. By solving the model with the program code, a method of analyzing the aerodynamic characteristics of the combined vertical axis wind turbine is given. The characteristics of attack angle, normal force, tangential force, and power coefficient of the combined wind turbine with different tip speed ratio are obtained by using the analytical model. The Navier–Stokes equation is solved by SST(Shear Stress Transfer) k–w turbulence model (four equations) in fluent 16.0 software. The tangential force coefficient, power coefficient and starting ability of the combined wind turbine are obtained by computational fluid dynamic method. The accuracy of the analytical model in solving the aerodynamic performance of the combined wind turbine is verified by comparing the solution results of the analytical model with the simulation results.