Abstract：In recent years, the vertical axis wind turbines (VAWT) which take Savonius wind turbine as a typical representative have rapidly developed. In order to verify the influence of Savonius wind turbine parameters on static starting performance, the overlap ratio was taken as a study object, and three kinds of Savonius wind turbine models with different overlap ratios, namely 0, 02, 05 were selected, using PIV test system to analyze flow field around blades under the conditions of the same Reynolds number and different azimuth angles. At the same time, the numerical simulations were carried out for the corresponding models, and the torque characteristics and surrounding flow field were analyzed. The distribution of vortex and energy utilization of Savonius wind turbine with different overlap ratios were revealed by comparing the experimental with the calculated result. The results show that the rotor with a certain degree of overlap ratio can eliminate vortex flow near the blade attachment surface, which can make the flow more stable, enhance the torque coefficient and improve the static starting performance; however, too large overlap ratio will weaken the direction of the airflow in the clearance, and it is easy to cause new vortex which reduces its static starting torque, so only the appropriate overlap ratio can improve the static starting performance of Savonius wind turbine.
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