Modification of the Vertical Axis with Variations in the Number of Blades of the Savonius Wind Turbine

The potential wind speed in Indonesia is generally low at 3 m/s to 7 m/s so that this type of vertical axis turbine is considered very suitable for use in wind conditions in Indonesia. There are several types of vertical axis wind turbines. One type of vertical axis wind turbine is the Savonius wind turbine. Many advantages that this type of wind turbine has, such as being able to receive wind from all directions, easy and cheap to manufacture, and can rotate at a fairly low angular speed. This test was carried out to determine the performance of conventional and modified savonius turbines with 2 and 3 blades variables in each turbine blade shape. The form of modification made is by changing the shape of the blade twisting by 45o. The turbine is carried out on a laboratory scale with a wind source using a fan that is directly opposite the turbine. The results showed that the highest turbine power occurred in a modified 2-blade turbine, namely 1.88 Watt with a torque value of 0.04 Nm and a shaft rotation of 450 rpm. The highest rotation value is also obtained by 2 modified blades at a wind speed of 6 m/s producing 896 rpm. However, the highest torque value is obtained by a conventional 2-blade turbine with a value of 0.136 Nm. The highest turbine efficiency in each turbine is obtained by a modified 2 blade turbine with an efficiency value of 36.92% while the highest turbine efficiency for a modified 3 blade turbine reaches 11.69% which is considered less efficient than other turbines.