Influence of Low-Level Jet intensity on aerodynamic loads of horizontal axis wind turbine rotor

ABSTRACT High wind speeds associated with Low-Level Jet (LLJ) make wind resources more favorable for wind energy production. However, the aerodynamic loads of large-scale horizontal axis wind turbine (HAWT) rotor under different LLJ inflow conditions have not been thoroughly studied. To gain insight into the aerodynamic loads of rotor under LLJ inflow conditions with different LLJ intensities, a method to establish an engineering LLJ inflow model was proposed according to the plane wall jet theory and Von Karman spectra model with user-defined scaling. The parameters in the engineering LLJ inflow model were determined by comparing the wind speed distribution obtained from the GP_LLJ spectral model, which was summarized from field measurements in the real atmosphere. The LLJ fluctuating wind fields with different intensities generated by the engineering LLJ inflow model were used as the inflow conditions of Fatigue, Aerodynamics, Structures, and Turbulence (FAST) open source code to calculate and analyze the aerodynamic loads of the HAWT. It was found that the engineering LLJ inflow model can be used to establish the LLJ inflow condition of HAWT. When the LLJ height is located at the hub height and LLJ intensity increases from 8 to 16 m/s, the RMS rotor unbalanced aerodynamic load coefficients, including ones of lateral force, longitudinal force, tilt moment and yaw moment are increased by 2.2, 2.13, 1.02 and 0.95 times, respectively