| With the rapid development of global technology and economic civilization,the global stone energy reserve is about to be exhausted,and the rational use of renewable energy has become a hot topic.Wind power generation is one of the most reasonable way of the utilization of renewable energy.In natural conditions,wind turbines cannot track the changing wind direction in time,and are often in yaw state during operation.At the same time,the influence of low-level jets on wind turbines has attracted people’s attention.In this project,a 1.5MW three-blade horizontal-axis wind turbine is numerically simulated to investigate the effects of low-level jets on the aerodynamic performance of horizontal-axis wind turbines under yaw conditions,the research work including the following aspects:(1)Simulate calculation on the wind turbines with wind shear and low-level inflow conditions,and compare the effects of the two inflow conditions on the aerodynamic performance of the wind turbine under yaw conditions.The results show that under the same yaw angle,the low-level jet stream enhances the blade flow separation,increases thrust and torque fluctuations of the wind wheel and the blade,the output power of the wind wheel.The blade thrust has a double-peak curve with azimuth change.Wind turbines,blades are subject to greater aerodynamic forces and moments than shear inflow.(2)With the increase of yaw angle,the aerodynamic forces of the wind turbines decrease under the two inflow conditions,the wind wheel power attenuation accords with the cos3γ rule;the blade flow separation phenomenon increases under the lowaltitude jet,and the symmetry of the blade thrust with the azimuth curve disappears.The peak value of the blade yaw moment decreases at the azimuth angle of 90°,and reach the peak value at the azimuth angle of 270°.The phenomenon of the lateral drift of the wake after the wind wheel becomes more apparent,and the wake expansion effect reduced and the tail is reduced.The flow center appears to be tapered,and the downstream influence area is reduced.(3)When the yaw angle is 15°,we explored the influence of the change of the jet strength on the aerodynamic performance of the wind turbine.The results show that with the increase of jet strength,the wind turbine power and thrust increase,the aerodynamic forces,aerodynamic moments of the wind turbine and the blade increase,and the flow separation on the blade surface increases.The high-speed zone at the leading edge of the blade grows along the chord direction,and the wake loss after the wind turbine is significantly improved.(4)When the yaw angle is 15°,we focus on the influence of the jet width variation on the aerodynamic performance of the wind turbine.Research shows that the change of jet width has a great influence on the aerodynamic performance of the wind turbine.As the width of the jet increases,the thrust and power of the wind turbine increase,and the peaks of the aerodynamic and aerodynamic torque curves of the wind turbine and the blade gradually decrease.When the rapid flow width is 11.25 m,there is abnormal fluctuation.At the same time,the blade flow separation is enhanced,the axial speed of the wind wheel is increased,and the high-speed zone of the leading edge of the blade extends along the exhibition direction.(5)Compare the influence of different jet flow heights on the aerodynamic performance of the wind turbine under yaw conditions.The results show that the change of jet height has no obvious effect on the thrust and power of the wind turbine.When the jet height is the hub height,the peaks of the aerodynamic and aerodynamic moments of the rotor and the blade are the largest,and the number of fluctuations increases.As the jet height rises,the blade flow separation increases,and the blade thrust,torque,and yaw moment peak positions move outward.The increase of jet height has improved the speed loss in the near-tail region after the wind turbine,but as the wake flows downstream,its loss tends to be severe with the increase of the jet stream height. |
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