The objective of this study is to show the effect of guide vane solidity on the performance of straight-bladed vertical axis wind turbine. The experimental study was carried out by a wind tunnel. The wind tunnel with a diameter of 1.8 m is open jet type. The rotor has three straight blades with a profile of NACA4518, a chord length of 100 mm, a diameter of 600 mm and a blade height of 700 mm. The guide vane consists of some arc plates. The wind velocity is constant at 8 m/s.
Floating offshore wind farms are being considered for Japanese waters. In such case, in order to control behavior of the float, it is very important to use a vertical axis wind turbine which has low center of gravity. As such wind turbine, a straight-bladed vertical axis wind turbine (this is named "S-VAWT" in the study) has been developed and investigated so far (Islam et al., 2008; Eriksson et al., 2008). This turbine consists of several aerofoil vertically mounted on a rotating shaft. Although the turbine needs a bearing at the top of the structure and has complicated aerodynamic interaction between the downwind blades and the wakes of the upwind blades, it has some advantages in comparison with a horizontal axis wind turbine (HAWT):
The center of gravity is relatively lower because the generator and gearbox can be placed on the ground.
A yaw mechanism to turn the rotor against the wind is not necessary for the turbine system. On the other hand, however, there are substantial drawbacks of S-VAWT.
That is, the power coefficient and self-starting characteristic of S-VAWT are less than those of HAWT.