Abstract
Wind turbines inevitably experience yawed flows, resulting in fluctuations of the angle of attack (AOA) of airfoils, which can considerably impact the aerodynamic characteristics of the turbine blades. In this paper, a horizontal-axis wind turbine (HAWT) was modeled using a structured grid with multiple blocks. Then, the aerodynamic characteristics of the wind turbine were investigated under static and dynamic yawed conditions using the Unsteady Reynolds Averaged Navier-Stokes (URANS) method. In addition, start-stop yawing rotations at two different velocities were studied. The results suggest that AOA fluctuation under yawing conditions is caused by two separate effects: blade advancing & retreating and upwind & downwind yawing. At a positive yaw angle, the blade advancing & retreating effect causes a maximum AOA at an azimuth angle of 0°. Moreover, the effect is more dominant in inboard airfoils compared to outboard airfoils. The upwind & downwind yawing effect occurs when the wind turbine experiences dynamic yawing motion. The effect increases the AOA when the blade is yawing upwind and vice versa. The phenomena become more dominant with the increase of yawing rate. The torque of the blade in the forward yawing condition is much higher than in backward yawing, owing to the reversal of the yaw velocity.
Highlights
The use of wind power has grown rapidly over the past few decades
The main novelty the current of this study was to investigate the effects of yaw on the dynamic output power, rotor thrust, and the work is the inclusion of the dynamic yawing simulation of wind turbine with the multiple structured blade sectional aerodynamic characteristics caused by continuous changes in the yaw angle
This paper has presented the results of unsteady numerical simulations investigating the static and dynamic aerodynamic performances of a National Renewable Energy Laboratory (NREL) 5-MW horizontal-axis wind turbine (HAWT) under yawed and yawing conditions
Summary
The use of wind power has grown rapidly over the past few decades. The aerodynamics of the wind turbine are a core subject of wind power generation. For larger windyawing turbineprocess and modeled the turbine as5aand structured grid withPhase moving boundaries Simulations wind turbines, such as the NREL 5-MW et al, these yaw rate seem to be impossible owing to the were performed with a yaw rate of 0.3◦ /s and 3◦ yaw angle and the results showed that overall power larger moment of inertia of the rotor-nacelle subsystem due to enlargement of the blade and tower under the dynamic yawing condition was much larger than for the yawed case. The main novelty the current of this study was to investigate the effects of yaw on the dynamic output power, rotor thrust, and the work is the inclusion of the dynamic yawing simulation of wind turbine with the multiple structured blade sectional aerodynamic characteristics caused by continuous changes in the yaw angle.
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