Study of Aerodynamic Loads Acting on Wind Turbines under the Typhoon Conditions in Taiwan
Date Issued
2016
Date
2016
Author(s)
Yang, Chun-Yu
Abstract
In Taiwan, the wind turbine that has been certificated by the international certification organization, such as GL, was still collapsed during typhoon. So, it is necessary to discuss if the design requirements of wind tirbine described in IEC61400-1 satisfied the environment of typhoon. There is no design load case defined for the conditions of wind turbine during typhoon in IEC61400-1, the guideline for design requirements of wind turbine. Although the standstill situation and wind condition of DLC6 and DLC7 are corresponding to the wind turbine with extreme wind speed during typhoon, but the gust during typhoon is not included. For these reasons, the recorded wind data during typhoon is analyzed to propose the extreme wind speed and gust model that corresponding to the wind condition during typhoon in Taiwan. Then, the characteristics of aerodynamic load acting on the wind turbine are studied by the numerical simulation of the flow field around the wind turbine with the proposed wind conditions mentioned above to be the reference for design, purchase and reinforcement of wind turbine in this article. According to the statistical analysis of the data that recorded by Chang-Kung anemometer during typhoon, the 1 minute average wind speed is 36m/s, the maximum 3 seconds average wind speed is 45.36m/s, the gust factor is 1.26 and the maximum instantaneous wind speed is 64.85m/s. And then the flow field around the NREL 5MW wind turbine with extreme wind speed and gust mentioned above are simulated by solving the RANS equations and SST k-w turbulence model. The simulating results of the gust case show that the drag and pitch moment of the wind turbine are not the extreme values while the wind speed being the maximum during typhoon. Moreover, the simulating results of the gust case also show that the extreme drag, the extreme pitch moment, the extreme rotor moment and the extreme yaw moment are larger than those of the extreme wind speed case that the wind speed is constant and is equal to the maximum wind speed during gust. The extreme drag of the gust case is 1.50 times of the extreme wind speed case, the extreme rotor moment of the gust case is 1.40 times of the extreme wind speed case and the extreme yaw moment of the gust case is 1.35 times of the extreme wind speed case. According to the simulating results, the extreme aerodynamic loads acting on the wind turbine will be under estimated if the wind condition is the fixed extreme wind speed that is corresponding to the wind condition of DLC6 and DLC7. Therefore, the gust should be considered as one of the wind condition for the design load case with standstill situation.
Subjects
Typhoon
Extreme Wind Speed
Gust
CFD
Type
thesis
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