| From the development history of wind turbines,both the total installed capacity and the newly added installed capacity of wind turbines all over the world show exponential growth,which leads to the increasing capacity of wind turbines,and the onshore wind power can no longer meet the needs of human development,and is constantly expanding towards offshore wind power.With the increasing capacity of wind turbines,the obvious problems are that the sweeping area of wind turbines’ impellers is constantly expanding,the mass is constantly increasing,and the blades are getting longer and longer,which leads to a series of transportation and installation problems.Because of the huge volume of wind turbines and noise problems,the location of wind farms is constantly restricted.Therefore,it is of great significance to study the multi-rotor wind turbine.In this paper,wind tunnel experiment and Lattice Boltzmann（LBM）method are used to conduct numerical simulation research on different wind wheel spacing of multi-wind turbine,and the power cost is estimated,and its advantages and disadvantages are compared.Three kinds of arrangement modes of multi-rotor are designed and their stability is analyzed.The results show that the thrust of the rotor is related to the rotation speed of the rotor,but not to the arrangement mode.By comparing the torque in the direction of the main tower of the three arrangements,it is found that the torque in the longitudinal arrangement and the triangular arrangement is smaller,and the lateral distribution is obviously unstable.Meanwhile,by comparing the numerical simulation with the experimental data,the relationship between the power and wake changes of double-rotor wind turbines and three-rotor wind turbines with tip distances of 0.1 d,0.4d and 0.9d（d is the diameter of small wind turbines）and single-rotor wind turbines with the same area is studied.The results show that the output power of double-windwheel and triple-wind-wheel wind turbines increases at first and then decreases with the increase of wind-wheel spacing.Compared with single-wind-wheel wind turbines with the same area,the output power of double-wind-wheel and triple-wind-wheel wind turbines can increase by 7.3%and 8.4%respectively at the tip distance of 0.4d:When the tip distance is 0.9d,each rotor of the multi-rotor wind turbine runs relatively independently,but the output power increases by 2.3%and 2.7%.The numerical simulation results are slightly lower than the experimental measurement results,because the output power of the three-rotor wind turbine is increased by 4.56%under the condition of 0.4d wind wheel spacing and 1.4%under the condition of 0.9d compared with the single-rotor wind turbine with the same area.In wake,under the condition of uniform flow,the multi-rotor wind turbine has faster wake recovery ability than the single-rotor wind turbine with equal area.The turbulence intensity at different axial distances,especially near the wake,is relatively smaller.At the same time,the cross wind speed of multi-rotor wind turbine is larger than that of single-rotor wind turbine.When the turbulence intensity of the incoming flow is 10.5%,the wake velocity loss becomes smaller and the speed recovery ability is faster.However,the wake width of multi-rotor wind turbines is generally wider than that of single-rotor wind turbines with equal area.With the increase of wind wheel spacing,the wake recovery ability is similar.Finally,the cost and total cost of each part of single-rotor wind turbine and three-rotor wind turbine are compared,and the annual power generation is estimated,and the electricity cost is calculated.The results show that the total cost of three-rotor wind turbine is about 95%of that of single-rotor wind turbine,and the electricity cost is about 91%of that of single-rotor wind turbine. |
PDF Full Text Request