Aerodynamic Performance Analysis And Optimization Of Vertical Axis Wind Turbines

Wind turbines can convert wind energy into electric energy,and the power generation is green and pollution-free,which has huge ecological and social benefits.Compared with horizontal axis wind turbines,vertical axis wind turbines have the advantages of no yaw device,low noise and convenient installation and maintenance,but they also have the disadvantage of low power coefficient.Based on this,the aerodynamic performance analysis and optimization of a vertical axis wind turbine are studied to improve its power output.Therefore,this paper takes an H-type vertical axis wind turbine with straight blades as the research object,and carries out the following research based on the computational fluid dynamics(CFD)technique:(1)Aerodynamic performance analysis and power output prediction based on a hybrid metamodel of the wind turbine.First,the key parameters of CFD modeling are studied in detail,and the reasonable modeling parameters are determined by comparing with the experimental data,which provides modeling guidance for the following simulations.Then,CFD models with different complexity are established to analyze and compare the aerodynamic performance of the wind turbine.Finally,considering the strong nonlinearity among tip speed ratios,wind speed and power coefficients as well as the high cost of CFD simulations,a hybrid metamodel is constructed based on a polynomial regression metamodel and a neural network metamodel to predict wind turbine power output.The simulation results show the effectiveness of the prediction model.(2)Design of variable-pitch control system based on torque coefficient maximization of the vertical wind turbine.Based on the principle of torque coefficient maximization,the improved artificial fish swarm algorithm based on the differential evolution algorithm is used to optimize the pitch angle under different tip speed ratios and different azimuthal angles.The pitch controllers are designed using the hybrid-meta model and the look-up table method,and their performances are compared and analyzed.The results show that the pitch control can improve the power output of the wind turbine to some extent,and the performance of the control system based on the hybrid metamodel is better.(3)Study on parameter optimization of an upstream deflector and influences of configuration parameters on system performances of a double wind turbine systemThe effects of different deflector parameters on the aerodynamic performance of the wind turbine are studied.The results show that the reasonable arrangement of the deflector can effectively improve the performance of the wind turbine.Meanwhile,based on the hybrid-meta model,the wind turbine power output under different deflector parameters and tip speed ratios is predicted,and the optimal deflector parameters under different tip speed ratios are then determined.An orthogonal experiment is designed based on the Taguchi experimental method,and the contribution of the parameters to the performance of the wind turbine system is determined by analyzing the signal-to-noise ratio.The results show that the blade tip speed ratios,incoming flow angles and blade number have significant influence on the power coefficient of the wind turbine system,while the influence of wind turbine rotation and wind turbine distance is small.