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This study investigates the effects of wind shear and wind shear coefficients on the near wake of a wind turbine. A wind turbine is subjected to the effects of wind shear, which leads to unsteady performance of the blade and characteristics of the blade near the wake. Wind shear coefficients of 0.1, 0.2, and 0.3 are used. The results are obtained using the three-dimensional incompressible Reynolds-Averaged Navier-Stokes equations, and the turbulence, are simulated via the shear-stress transport k–ω turbulence model. The flow of the air and, in particular, the axial velocity and tangential velocity are strongly affected by the rotation in the region of the blade near wake. There is an obvious velocity deficit at the near wake when the air flows over the blade, and this velocity deficit gradually decreases as the air flows downstream. The torque of the blade and the characteristics of the blade near wake periodically change with the effect of wind shear. The axial, tangential, and radial velocities and the turbulence intensity are strongly affected by wind shear at the region of the blade near wake, with the radial velocity particularly affected. The influence is more obvious as the shear coefficient increases. The effects of wind shear on the axial, tangential, and radial velocities and the turbulence intensity increase as the air flows downstream.

Wind energy is a widely used and developed the renewable energy, which has developed rapidly. At present, the design of the horizontal axis wind turbine blade mainly used Blade Element Momentum theory. In this paper, an optimization method of the wind turbine blade was proposed for improving the output power. The local twist angles of the blade were optimized. This method combined the surrogate model and the numerical simulation methods. The kriging surrogate model was selected and the next calibration point was chosen by the efficient global optimization algorithm. In this paper, the aerodynamic performances of the optimized blades were discussed in detail and obtained by the numerical simulation method. It was shown that the wind power coefficients and the output powers of the optimized blades were increased. The wind power coefficients of two optimized blades were increased by 4.83% and 3.44%, respectively. The optimized blades were able to capture more kinetic energy from the wind, but the optimized blades were subjected to a greater structural load. The thrust and torque coefficients maintained an increasing tendency for the optimized blades.

In this paper, the numerical simulation was used to investigate the effects of the leading-edge slat installation angles ( β for airfoils from 0° to 40° and β1 for blades from −20° to 40°) on the aerodynamic characteristics of the airfoil and the wind turbine blade. The chord length of the leading-edge slat is 0.1c (the chord length of the clean airfoil). The horizontal and vertical distances from its center to the leading edge of the clean airfoil are 0.005c and 0.009c, respectively. The results indicated that the lift coefficient could be significantly improved by the leading-edge slat (except β = 40°) when the attack angle exceeded 10.2°. For β = 0°, the lift coefficient increased the most. The trailing vortex of the leading-edge slat played an important role at the process of flow control. It could transfer kinetic energy from the bounder layer to its out-flow region. Furthermore, the vorticities of trailing vortex generated by the leading-edge slat with different installation angles were different, promoting several effects on the airfoil at the different cases. The torque of the blade with leading-edge slat (except β1 = −20°) was improved significantly as the leading-edge slat trailing-vortices became stronger with the higher wind-speeds.