Research On Aerodynamic Characteristics Of Horizontal-axis Wind Turbine Under Sand-wind Environment

Wind energy has been large-scale developed and utilized as a renewable energy in recent years. At present, the turbines put on the horizontal axis variable pitch turbine, and the runner is the most important part to converting energy. For the wind turbine under the sand environment, this paper use the method of numerical simulation, studying the influence of different sand volume fraction and particle diameter on the variable wind speed, the rotor torque characteristics under the constant wind speed and the sand flowing law.1. Effect of different sand volume fraction on the rotor torque characteristicsWhen the particle diameter is constant, changing the wind speed, at3-17m/s, the rotor torque increases with increasing sand volume fraction, and is larger than that in clean air. At3-7m/s, the rotor torque in low wind speed area is not sensitive to the increase of the volume fraction, as it has little increased with the increasing volume fraction;While wind speed7-17m/s the rotor torque in high speed wind area increase more with the increasing volume fraction, so it is sensitive to the increase of the volume fraction.At17-24m/s, the increase of the rotor torque with the increasing volume fraction is smaller than the clean air.When the wind turbine goes into a stall at high wind speed, the flow is turbulent flow. The particles aggrevate the flow separation, which lead to the decreace of output.The rotor torque increase with the increasing sand volume fraction in a constant speed.There is relatively larger increase of torque when the volume fraction is0-4%. while the torque increase with the increasing volume fraction is slow sharply when the volume fraction is in4%-9%, but the overall increase is relatively stable. Besides, the torque is larger in sand environment than that in clean air. Although there is not distinctive difference between the volume fraction of2%and4%. the torque is larger than that in clean air.2.Effect of different particle diameter on the rotor torque characteristicsWhen the sand volume fraction is constant, changing the wind speed, at3-17m/s, the rotor torque increases with the increasing particle diameter, and is larger than that in clean air. At3-17m/s wind speed area, the rotor torque is not sensitive to the increase of the volume fraction, as it has little change with the increase of volume fraction; While wind speed7-17m/s the rotor torque increase more with the increasing particle diameter in high speed wind area,and it is sensitive to the increase of particle diameter.Moreover,the rotor torque decrease with the increasing sand volume fraction, at17-24m/s.And the rotor torque of sand containing air flow is less than that of the clean air, as the rotor deeply stall in high wind speed region, which lead to the flow disturbance along the airfoil.At a constant speed, the rotor torque increase with the increase of the dust particle median diameter. The torque increases with the increasing particle diameter in0-0.05mm.While it decreas with the increasing dust particle diameter in0.05-0.2mm.However, the torque in sand environment than that in clean air.In a word, the change of the sand volume fraction and particle diameter could increase the rotor torque in a certain range of wind speed, and the output is higher than that in clear air. When the wind speed exceeds a certain point, the wind turbine begins to stall, and the output reduces. As sand has exacerbated flow turbulence, making the wind turbine’s output smaller than that in clean air.So the research of the change of volume fraction and sand particle diameter has great significance for the output in sand environment.