A Study of Blade Pitch Variation for Vertical Axis Wind Turbines

The types of small wind turbine products manufactured in Taiwan can be divided into two categories: horizontal axis wind turbines (HAWT) for power greater than 1 kW; vertical axis wind turbines (VAWT) otherwise. Even though VAWT is famous for its low efficiency, if the yaw effect of HAWT is taken into account, VAWT outperforms HAWT in the long run. However, to gain the full advantage of VAWT is not easy because a Savonius VAWT (SVAWT) operates in low efficiency (＜ 0.1) while start-up easily. On the other hand, a Darrieus VAWT (DVAWT) operates in much higher efficiency (~ 0.4) while hardly start-up at low wind speed. The remedy to this may lie on varying the blade-pitch of a DVAWT so that it start-ups at low wind speed as well as operates in a high efficiency close to that of an HAWT. Furthermore, the idea of mass-stabilizer can be used in a way that the slightly unbalanced mass may vary the blade-pitch to reduce the over-speed of rotor and prevent it from breaking down. In the first year of the two-year plan, we plan to establish an aerodynamic analysis system for evaluating several ways of blade-pitch variation in searching for the effective way that is easy to be realized. According to the way, a DVAWT will be designed and built. In the mean while, the established vehicle-mounted test bench for HAWT will be modified into one that can be used for verifying the performance of the designed DVAWT. In the second year, we plan to test the designed DVAWT linked with a generator for long-term performance and endurance. The test bench will also be the modified version of the previously established test bench for HAWT. The resulting data can be compared with those taken from the previously developed small HAWT with varying blade-pitch so as to demonstrate the superiority of the DVAWT over HAWT in urban erea.

Project ID:PB10308-2521
External Project ID:MOST103-2221-E182-063