PERFORMANCE ANALYSIS OF SAVONIUS-STYLE WIND TURBINES UNDER CONCENTRATED AND ORIENTED JETS

摘要

With the rapid growth of renewable energy sector, vertical axis wind turbines are finding their applications in the small-scale distributed wind energy system, particularly in rural areas. These turbines are simple in construction and easy to install with comparatively lower cost. However, the efficiency of these turbines is not competitive to that of horizontal axis wind turbines. In this paper, an attempt has been made to improve the efficiency of a Savonius-style vertical axis wind turbine under concentrated and oriented jets through installation of deflectors at different positions ahead of the turbine. The aim is to make the major portion of the flow to be incident on the concave part of the blades. Experiments are conducted in a low speed wind tunnel with an open test section facility. For all the experiments, the wind speed in the tunnel is kept constant at 6.2 m/s. The mechanical loads are varied to analyze the performance of the turbine at various tip speed ratios. In each case, both power and torque coefficients are calculated in order to estimate the performance indices of the turbine. Moreover, a suitable operating range of this turbine is specified. The present investigation demonstrates that with the installation of deflectors, the performance of the Savonius-style wind turbines can be sufficiently improved under concentrated and oriented jets. The peak power coefficient of 0.32 is achieved with an optimized position of the deflectors in front of both the advancing and returning blades.