Influence Of Building Turbulence On Performance Of Distributed Wind Turbine Under Different Wind Conditions

In recent years,in order to cope with the increasingly severe environmental pollution and energy crisis,it has become a trend to adjust the energy structure and promote the industrialization of renewable energy.With the advantages of clean and easy access to wind resources,wind power technology has developed rapidly in the past few decades.At present,one of the challenges of wind farm development is the relatively scattered distribution of wind energy.Compared with traditional wind turbines,decentralized wind turbines can realize the decentralized utilization of wind resources,which is the current research hotspot.However,the installation environment of distributed wind turbine is complex,especially when there are buildings in the upstream,different incoming wind conditions will cause changes in the flow field characteristics of wind turbine,and affect its operation performance.By adjusting the layout of wind turbines in wind farms,the utilization rate of wind resources can be improved,and the service life of wind turbines can be extended to a certain extent.In view of the above problems,the research group explored the influence of the distance between the wall and the fan,the installation height of the wind turbine and the incoming wind speed on the wall disturbing area under the wall disturbing environment,and determined the installation location of the wind turbine.Based on previous work,considering the two conditions of inflow turbulence and wind shear,this paper studies the effect of building disturbance on the flow field characteristics of decentralized wind turbines under different wind conditions,and further verifies the applicability of the installed location of the selected wind turbines.In this paper,the CFD model including the wall and the wind turbine is constructed by simulating the real use conditions,in which the wall is located in the upstream of the wind turbine.Vertical axis wind turbine is selected as the research object,based on computational fluid dynamics,sliding grid technology and RNG k-ε model,the aerodynamic characteristics of vertical axis wind turbine are studied.In addition,the influence of disturbance of buildings on the performance of distributed wind turbine under different wind conditions is analyzed:(1)The influence of tip speed ratio on the output power and flow field of vertical axis wind turbine under building disturbance is studied.Among them,with the increase of blade tip speed ratio,the power factor and output power of wind turbines first increase and then decrease.When the wind turbine output maximum power,the corresponding tip speed ratio is 3.4.Moreover,the influence of building disturbance on wind turbine flow field increases when the tip speed ratio increases.When it increases to a certain extent,the power and torque of wind turbine decrease sharply.In addition,the turbulent kinetic energy in the center of the wind turbine decreases correspondingly,which affects the performance of the wind turbine.(2)The influence of inflow turbulence on the bare machine of wind turbine is analyzed,and the influence of building turbulence on the aerodynamic characteristics of wind turbine is studied.The aerodynamic characteristics and starting performance of wind turbine are affected by turbulence intensity.For the vertical axis wind turbine with tip speed ratio of 3.4,with the increase of turbulence intensity,the wind energy utilization coefficient,power and torque coefficient of the wind turbine first increase and then decrease.When the turbulence intensity is between 10%and 15%,the wind energy utilization coefficient is the maximum,and the power and torque coefficients are also the optimal values.Hence,the self starting performance of the wind turbine is the best.(3)In the building turbulence environment,the inflow turbulence intensity will affect the power characteristics of the wind turbine.With the increase of the inflow turbulence intensity,the wind energy utilization and work efficiency of the wind turbine will decrease.In addition,due to the inflow turbulence caused by building disturbance,the flow field near the wind turbine has a strong velocity fluctuation,which affects structural performance and aerodynamic characteristics related to the downstream wind turbine.The results show that the wind speed of the wind turbine is lower than the wind speed cut out under different turbulence intensities,and the turbulence intensity does not exceed the high turbulence scale line TI=0.25,which verifies the adaptability of the selected wind turbine installation position under different inflow turbulence.(4)In terms of wake,power and flow field characteristics,the effects of different inflow wind shear on the combined vertical axis wind turbine is studied.It is found that the larger the wind shear index is,the faster the wind energy increases with the height,and the greater the wind speed gradient is.Therefore,when passing through buildings,the greater the wind speed gradient is,which has a negative impact on the operation performance of wind turbine.However,under different wind shear coefficients,the wind speed and turbulence intensity at the position of the wind turbine are within the allowable range of normal operation of the wind turbine.In this paper,the aerodynamic characteristics,wake and flow field of the combined vertical axis wind turbine under different wind conditions are deeply studied,which provides theoretical support for the design optimization of the vertical axis wind turbine under the building turbulence environment,and has important guiding significance for the selection of the installation position of the wind turbine.