The Study on a Three-stage Blade-pitch Adjustment Mechanism for Small Horizontal Axis Wind Turbines

• Main Authors: Yan Jie Huang, 黃彥傑
• Other Authors: M. T. Sun
• Format: Others
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/33217772692912156194

碩士 === 長庚大學 === 機械工程學系 === 102 === The most profitable wind energy product in Taiwan is small horizontal axis wind turbine. In order to excel in the field, the mechanism that enables the turbines to have low startup wind speed for mild southwest seasonal wind in summer and protect them from damage by strong northeast monsoon in winter and the frequent typhoons must be developed. The purpose of this study is therefore to develop a mechanism that varies the blade pitch by the centrifugal force of the blade and a swing rod in three stages. To do so, the blade is firstly designed and analyzed to determine the specifications of the mechanism. Secondly, the mechanism parts are designed, fabricated, and assembled. Then, the assembly is tested on a variable speed drive to verify the functionality of the mechanism and find the blade-pitch adjustment as a function of rotational speed. Finally, the field test of the mechanism is carried out on a vehicle-mounted test bench. The results show that the power coefficient of the blade is about 4.3. In the adjustable speed drive tests, for the first-stage the mechanism acts as expected but for the third-stage the mechanism falls short of specifications. In the vehicle-mounted test, start-up wind speed is as low as 1.5 m/s. The blade pitch comes to a fixed value of 5 not 0 for 100 rpm or more of rotor speed due to the clearance of the mechanism. The mechanism reaches the third stage at a lower rotor speed of 700 rpm than the expected 800 rpm and the blade pitch reaches a 25 maximum value not the expected 30. This phenomenon may be caused by the excessive pitching moment under high wind speed relative to the blades.