| The characteristics of the atmospheric boundary layer,especially the shear and turbulence of wind,have an important impact on the load,power and wake performance of wind turbines.In the natural environment,the characteristic parameters of the atmospheric boundary layer are difficult to be quantitatively controlled,and it is one of the important means to study the influence of the atmospheric boundary layer on the performance of wind turbines by obtaining a repeatable and controllable natural wind environment through wind tunnel experimental simulation methods.Therefore,according to the experimental simulation method of atmospheric boundary layer wind tunnel,the first set of active grid device in China was developed,and the turbulence characteristics and wind shear characteristics of the atmospheric boundary layer were simulated in the wind tunnel,and the main work content was as follows:1.A active grid device to simulate the characteristics of the atmospheric boundary layer was developed.Based on the structural strength check,flow field parameter range and load capacity demand,the mechanical structure system and electrical control system of the grid device were designed,and the control algorithm for turbulence and wind shear simulation was developed,which was applied in the large-scale low-speed reflux wind tunnel of North China Electric Power University.2.The quantitative influence of active grid device on the flow field quality of wind tunnel in the static fully open state was explored.The quantitative changes of the average wind speed and turbulence intensity in the flow field before and after the grid installation were measured through experiments,compared with the uninstalled,the average wind speed of the wind tunnel decreased by 5%,and the turbulence increased from 0.5%to 1.5%.The spatial uniformity of the downstream flow field of the grid device is verified by the experimental measurement of the wind tunnel extension and vertical space points.3.A wind tunnel experiment simulation method for the turbulence characteristics of the atmospheric boundary layer is proposed.The influence of control parameters such as angular acceleration a,rotation period T,Rossby number Ro and grid Reynolds number ReM on the flow field characteristics downstream of the grid was explored,and the mapping relationship between grid control parameters and turbulence parameters was established.The results show that the turbulence parameters are the most sensitive to the Rossby number Ro,and it is proved that the turbulence intensity adjustment range of the developed active grid device is 5%～39%,and the turbulence integral scale adjustment range is 0.15m～1.56m,which verifies that the device is suitable for wind turbine model experiments in the range of 1:20 to 1:1200 scale.4.A wind tunnel experimental simulation method for wind shear characteristics of atmospheric boundary layer is proposed.Through experimental comparison,the quantitative effects of different grid axis deflection,different vibration directions of adjacent grid shafts and different angle distribution on wind shear goodness fit were analyzed,and the experimental data set of horizontal grid axis angle distribution and wind shear profile was obtained,and the quantitative relationship between horizontal grid shaft opening and closing angle and wind shear index was established,and wind shear experiments were verified by four standard landforms A,B,C and D of Chinese building load codes.The simulated wind shear index simulation range of the laboratory is 0.05～0.4,and the simulation range of turbulence intensity under the same wind shear is 8.5%～15.1%.At the same time,by combining the horizontal grid shaft opening and closing angle distribution,vertical grid shaft speed,and downstream flow direction position parameters of the grid,the decoupling control of wind shear profile and turbulence intensity is realized. |
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