Optimization Design And Test Of Blades For The Scaled Floating Offshore Wind Turbine Model

Model test is a key step in the design process of offshore floating wind turbines.In model test,the thrust of geometrically similar blades is only20%~30%of the target value due to the"scale effect"caused by the difference of Reynolds number.In order to accurately simulate the aerodynamic loads on blades in model tests,a design method of model blades is proposed.Taking NREL-5MW offshore floating wind turbine as an example,a model blade with similar performance is designed according to 1:50 scale ratio,and its aerodynamic performance is verified by CFD method and wind tunnel test.A model blade optimization design method is proposed.Thrust and torque of blade caused by air action are the key factors affecting the movement and response of wind turbine system.Because the torque has much less impact on the wind turbine system than the thrust,and they are difficult to meet at the same time,the C_T(thrust coefficient)of NREL-5MW wind turbine under different TSR(ratio of blade tip linear velocity to rotational speed)the C_T of NREL-5MW wind turbine under different TSR is the design goal at the beginning of the design.SD7032 airfoil suitable for low Reynolds number is selected for model blade,its lift-drag coefficient is calculated by Xfoil,blade thrust is calculated by FAST software based on blade element-momentum theory,blade optimization model is established,data interaction between FAST and MATLAB is realized,and the optimization model is solved by mode search method in MATLAB.Under different conditions,the thrust of the optimized blade can meet the target value.Based on the CFD method,the blades designed in this paper are analyzed.The multi-reference coordinate system method is used as the calculation method.Calculate the results of two different turbulence models using RNG k-?and SST k-?respectively.The aerodynamic performance of the blade and the feasibility of the design method are preliminarily verified.By analyzing the pressure and streamline diagram of the blade,the stall area and the range of stall angle of attack of the blade under different working conditions are found,which can provide reference for the aerodynamic performance design of the blade.By analyzing the pressure distribution coefficient diagram of the blade,it is found that the maximum pressure on the blade is located at the guide edge of the blade root.When the blade is structurally designed,it is necessary to consider the strength of the zone and select the material reasonably.Based on wind tunnel test,the actual aerodynamic performance of the blade is verified.Before the test,according to the similar conditions and target parameters,the auxiliary tests of the tower,hub and engine room are designed.The first mode and frequency of the tower satisfy the target value,and the hub has the function of pitch changing.By comparing the experimental results with CFD simulation results,it is found that the SST k-?turbulence model has higher accuracy and applicability in the aerodynamic performance simulation of blades.Compared with the wind tunnel test results and thrust target values,the aerodynamic performance of the blade can meet the model test conditions,and the design method in this paper is feasible.