A new experimental technique for measuring both the average and instantaneous torque of Savonius wind turbines

The idea of designing the vertical axis windmill by Savonius was based on the principle of Flattener's rotor ship. The majority of performance results for these types of rotor have been obtained experimentally, and most of these experimental results are only related to the average performance (average torque and power). For example I/umi Ushiyama and Hiroshi Nagai [2] have experimentally determined the effects of the main design parameters on the aerodynamic performance of the rotors. Mozamel H. Khan [3] carried out a similar study and obtained similar results. From the previous studies it can be noticed that none of the previous researches have studied experimentally the instantaneous performance of the Savonius rotor. The analytical method described in [1] is applied to calculate the instantaneous torque of the Savonius rotor at any orientation and rotational speed. In this paper a new experimental technique has been developed to provide information about the average torque and variation of torque within a cycle. The agreement between these experimental results and the theoretical results show that they predict both the time averaged and the instantaneous performance. In this paper three models of Savonius rotor are used, the first and the second model are semi-circle (b/c= 0.0, b/c =0.25) and the third is Bach model Agreement with theoretical results for two different Savonius blade shapes tested has been excellent.