Improving the self-starting and operating characteristics of vertical axis wind turbine by changing center distance in part of blades

Abstract

Compared with the horizontal axis wind turbine (HAWT), the vertical axis wind turbine (VAWT) has the advantages of low noise operation and no wind yaw device. However, the poor self-starting performance of VAWT is one of key problems restricting its development. In order to improve the self-starting capability of VAWTs in urban wind areas, this paper proposed a VAWT model with multi-blade local variable radius. The main object of this study is to research the effect of reducing the partial blade radius on the self-starting performance and power coefficient of the VAWT. In this study, the partial blade radius of the VAWT models was reduced to 0.375, 0.5, and 0.625 times of the outer layer. The dynamic torques and velocity contours of the different models were researched by experiments and numerical simulations to analyze the reason why reducing the partial blade radius affects the power coefficient of the VAWT. The static torque and static pressure contours of different models were researched to compare the self-starting capability of the models. According to the results, the minimum static torque values of the three innovative VAWT models were increased by 0.1, 1.8, and 2.8 times, respectively, compared to the traditional VAWT with only the outer layer. Furthermore, the power coefficients of three models were increased for tip speed ratios (TSR) less than 2.2. Therefore, the new models can improve the self-starting capability of VAWTs, and the higher power coefficients at low TSRs make them more advantageous for applications in urban buildings and low wind speed areas.