## 3 Results and Discussion  
### Wind Turbine Thrust and Power Characteristics  
As an example, taking the inlet wind speed as 8 m/s and, in the rotating domain, taking the rotational speed of \(\lambda=5\), the calculation time was set as three times the dynamic yaw period; that is, 72 s. Through CFD simulation, the output torque of the wind turbine was selected to analyze the variation over time of the wind turbine model. As shown in Figure 7, the three-blade torque showed marked cyclical changes during the deflection period. The output torque of the wind turbine was the highest at a yaw angle of \(0^{\circ}\). The wind turbine's torque progressively declined to a minimum between the adjacent peaks as the yaw angle rose, then gradually rose to a maximum. Nevertheless, when the yaw angle was \(\pm 30^{\circ}\), the torque is the lowest. The research indicates that the fluctuations of the wind turbine's output torque curves remained essentially the same in the second and third cycles, indicating that the calculation stabilized in the second deflection cycle under the prevailing dynamic yaw state. We then investigated the data in the second cycle, at yaw times of 24 to 48 s. On the horizontal timeline, times of 24 s, 36 s, and 48 s corresponded to a yaw angle of \(0^{\circ}\), while times of 30 s and 42 s corresponded to a maximum yaw angle of \(30^{\circ}\) during positive and negative yaws, respectively. Additionally, in accordance with the definitions of positive and negative yaw  
Figure 6: Meshing. angles, blades 1 and 3 deflected in the same direction during the same yaw period, whereas blade 2 deflected in the opposite way. As shown in Figure 8, the axial thrust of a single blade of the wind turbine was distributed in a cosine state with respect to yaw fluctuation. The extreme values of blades 1 and 2 appeared at the same position, while the axial thrust of blade 2 was greater than that of blade 1, and the maximum thrust of blade 3 was observed during the negative yaw process. The axial thrust of blade 1, blade 2, and blade 3 increased by 0.55%, 0.54%, and 1.75%, respectively, compared to the non-yaw condition. The minimum axial thrusts of blades 1, 2, and 3 were observed in the negative and positive yaw half-cycles, and the three blades showed minimum values at a yaw angle of \(\pm\)30\({}^{\circ}\). The axial thrust of blade 1, blade 2, and blade 3 decreased by 19.97%, 15.4%, and 17.8%, respectively, compared to without yaw. The histogram in Figure 9 demonstrates that during positive yaw, downwind deflection always has a lower axial thrust than upwind deflection at the same deflection angle. When the yaw is negative, the axial thrust of blade 1 against the wind is always less than the downwind deflection, and the axial thrust of blade 2 against the wind is always greater than  
Figure 8: Axial thrust of a single blade. Figure 7: Torque of the wind turbine under dynamic yaw. the downwind deflection. The axial thrust of blade 3 against wind deflection is basically flat at yaw angles of \(-30^{\circ}\) to \(-20^{\circ}\), and the axial thrust of upwind deflection at angles of \(-20^{\circ}\) to \(0^{\circ}\) is greater than that of downwind deflection. There are two main reasons for the different changes in the blades: one is the relative position of the blades, and the other is the change in the relative wind speed. The change in azimuth with time can be expressed as  
\[\psi=\frac{360}{2\pi}\omega^{\prime}t\frac{1}{360} \tag{3}\]  
where \(\omega^{\prime}\) is the angular velocity of the wind turbine. In the calculation results, the quotient is the number of rotation rings of the wind turbine, and the remainder is the azimuth angle of the wind turbine. When the analyses of Equations (1) and (3) are combined, it becomes clear that the spatial location of the blades is constantly changing and that no blade is ever entirely in the same position, which causes the relative wind speed to fluctuate constantly as well.