Experimental Investigation of Shaft Mass Variation on the Performance of a Horizontal-Axis U-Type Savonius Wind Turbine under Low Wind Speed Conditions

Wind energy is one of the most promising renewable energy resources in Indonesia-however, its utilization remains limited due to relatively low average wind speeds, particularly in Java, which range from approximately 2.7 to 4.5 m/s. This study investigates the effect of shaft mass variation on the performance efficiency of a horizontal-axis U-type Savonius wind turbine designed for low wind speed applications. The research employed an experimental method by developing a prototype consisting of three U-shaped blades made of 0.3 mm clear polyvinyl chloride (PVC), with blade dimensions of 93 cm in length, 16 cm in diameter, and 8 cm in radius. To improve structural stability, each blade was equipped with four supporting ribs. Three different shaft materials with varying masses were tested: aluminum shaft (166 g), stainless steel shaft (453.5 g), and brass shaft (486 g). Experimental testing was conducted under laboratory-scale conditions using a blower and wind tunnel system with wind speed variations ranging from 1 to 10 m/s. The measured output parameters included shaft rotational speed, output voltage, and electric current generated by a DC generator. The experimental results revealed that the stainless-steel shaft (453.5 g) achieved the highest average efficiency of 2.41%, producing an average turbine power output of 2.37 mW at wind speeds between 2 and 6 m/s. The aluminum shaft generated an average efficiency of 1.42% with a power output of 2.37 mW, while the brass shaft produced an average efficiency of 1.96% with a power output of 2.59 mW. These findings indicate that shaft mass significantly affects rotational stability and energy conversion efficiency in low-speed wind turbine systems. This study highlights the potential of modified Savonius turbines for micro-scale renewable energy harvesting applications in low wind speed regions.