Experimental investigation into the improvement of self-starting capability of vertical-axis tidal current turbine

Indonesia has a lot of tidal current energy resources that can be harnessed using a vertical-axis turbine. However, one of the disadvantages of the vertical-axis turbine is its low self-starting capability. Under the actual condition, tidal current velocity is fluctuated and sometimes is very low, making the turbine unable to rotate. The purpose of this study is to investigate and improve the self-starting capability of a vertical-axis turbine. The study was conducted experimentally using a towing tank in Institut Teknologi Sepuluh Nopember (ITS) at Surabaya, Indonesia. The speed of towing carriage was set with the starting condition of 0 up to 0.4 m/s with an increment of 0.1 m/s. The stages of the test are as follows: first, the original vertical-axis turbine, a turbine with three straight-blades, was investigated; second, the modified vertical-axis turbine (inclined-blade) was proposed to increase the self-starting capability. The inclined-blade turbine has smooth self-start characteristics compared with the straight-blade turbine. It can start rotating at 0.2 m/s with a turbine rotation speed of 2.25 rpm. The original vertical-axis turbine with straight blades can start rotating at 0.3 m/s with a turbine rotation speed of 1.93 rpm. Therefore, a vertical-axis turbine modified with inclined-blades has better self-start capability that is suitable to implement in an area with low tidal current velocity.