Analysis of wind turbine power and aerodynamic loads influenced by four-dimensional spatiotemporal non-uniform wake

The aerodynamic characteristics of wind turbines operating in the wake region exhibit significant differences compared to those in free-flow conditions. In order to quantify the influence of wake on the aerodynamic characteristics of wind turbines, this paper proposes a method for calculating the aerodynamic characteristics of wind turbines based on a three-dimensional time-varying wake model (3DJGF-T) with a coupling-improved blade element momentum (BEM) model. Firstly, using sinusoidal and free-stream wind conditions as upstream turbine inputs, the 3DJGF-T wake model is employed to obtain the spatiotemporal characteristics of the wind field within the wake, and the external field experiments are conducted for validation. Secondly, utilizing the unevenly distributed flow field within the wake as the boundary condition in terms of spatial location points and time, the spatiotemporal variations of wind turbine rotor and single-blade power, torque, and axial force are investigated at different downstream longitudinal positions (x=5D, 6D, 7D, 8D) and horizontal positions (fully wake, 1/2 wake, 3/4 wake, and full-half wake) with the comparative analyses are performed. Results indicate that changes in the downstream longitudinal position will simultaneously alter the temporal and spatial characteristics of the wake, resulting in more complex fluctuations in load and power. With every increase of 1D in longitudinal distance, the rotor power increases by approximately 10%. In contrast, variations in the horizontal position of the wind turbine only affect the spatial characteristics of the wake, with rotor power losses gradually increasesing as the turbine approaches the center of the wake. Compared to the full-half wake, the relative average power losses of 1/2 wake, 3/4 wake, and full wake are 23.7%, 44.3%, and 61.2%, respectively. When the inflow is free wind, it exhibits faster variations in wind speed and stronger randomness compared to sinusoidal wind, causing greater fluctuations in the load power of the wind turbine.The findings of this study provide important reference value for wake regulation and micro-siting in wind farms.