Experimental and numerical investigation of novel Savonius wind turbine

Savonius wind turbines have distinct advantages in terms of simplicity, low noise, and ease of manufacturing, yet they are not preferred for large-scale power generation due to their lower aerodynamic performance and high wind loads. This study is aimed at reducing the thrust load with retractable type telescopic blades. This novel telescopic Savonius turbine is tested in an open jet wind tunnel to assess the performance in terms of torque, power, and thrust on the rotor. The dynamic and static characteristics are obtained for both extended and retracted configuration after correcting the experimental data for wind tunnel blockage. A preliminary numerical study is carried out in an effort to determine the variation of the drag coefficient in relation to the bucket thickness. The proposed telescopic turbine demonstrates a reduction in thrust load of 72.4% with a maximum power coefficient of 0.14 at the tip speed ratio of 0.7 compared to an extended operating configuration, similar to a conventional Savonius turbine. Thus, the telescopic Savonius turbine can be scaled up to higher kilowatt capacity with the cost comparable to other high-speed rotors such as Darrieus or horizontal axis wind turbines.