Aerodynamic characteristics of a parked horizontal-axis wind turbine under extreme wind with considering blade-tower interference

Aerodynamic characteristics of a parked horizontal-axis wind turbine (HAWT) are crucial for assessing its performance under extreme wind conditions. In this study, a scaled model of the NREL-5MW HAWT is fabricated to systematically investigate aerodynamic characteristics of the parked HAWT at different yaw and azimuth angles. The Reynolds number effect of the HAWT model is first simulated through surface roughness modification, followed by a series of wind tunnel tests to acquire detailed wind pressure on the parked HAWT at different yaw and azimuth angles. Based on the wind tunnel measurement data, effects of yaw and azimuth angles on aerodynamic characteristics of parked HAWT are examined, with a special focus on the blade-tower aerodynamic interference. Results show that wind loads on the tower can be increased significantly due to the existence of the blade, particularly in terms of the fluctuation component of the wind loads. While the mean overall drag on the blades increases with yaw angle, the mean overall lift and standard deviations of overall drag and lift on the blades reach their peak when yaw angle is around 30° to 50°. In addition, a common high-frequency signature in wind loads on the tower and blade is uncovered at the yaw angle of 50° based on spectral analysis. The HAWT at this yaw angle also has the most pronounced resultant base overturning moment, suggesting that this configuration may impose considerable wind loads on the HAWT and should be avoided in engineering practice.