Aerodynamic investigation of the start-up process of H-type vertical axis wind turbines using CFD

Abstract

In this study, a CFD start-up model has been built after conducting the sensitivity studies to evaluate the self-starting behaviour of the H-type vertical axis wind turbines (VAWTs). The self-starting behaviour of a well-investigated VAWT is used for the model validation, and then the details of aerodynamics of the start-up process have been examined. Finally, the effect of the moment of inertia and the blade number on the aerodynamic behaviour of the self-starting and power performance of the H-type VAWT are analysed. It has been found that in the critical region, where TSR<1, the contribution of the drag to the torque generation plays a significant role in the second and third quarters of the rotor revolution, where the azimuthal position varies between 100° and 253°. The results also show that increasing the turbine inertia did not show a noticeable effect on the start-up behaviour of the turbine and final rotational speed. However, an increase in the instantaneous turbine power during the start-up process after the optimum TSR is observed with decreasing the turbine inertia. The current findings also show that an increase in the blade number makes the turbine easier to start-up; however, this may reduce the turbine power coefficient.