Investigation On The Optimization Of Variable Pitch And Passive Control Device Of Straight-bladed Vertical Axis Wind Turbine

Wind turbine is the main device to collect wind energy,in which vertical axis wind turbine is concerned by industry because of its simple structure and little noise.Choosing the vertical axis wind turbine that can be installed in the small town as the research object,in order to improve its wind energy extraction efficiency,we propose two kinds of passive device model based on that the adjustment of blade pitch angle can significantly change the wind turbine aerodynamic performance and the research findings of active control of vertical axis wind turbine pitch.At last we demonstrate the validity of the passive device model through numerical caculation.The double disk multiple streamtube model is selected as the fast evaluation method of wind turbine performance through comparising with different streamtube models.By introducing the dynamic stall model and comparing with the experimental results,the accuracy of the modified model is improved.By simulating the change of blade pitch angle,it is proved that changing the pitch angle can significantly change the aerodynamic performance of fan.In order to obtain the optimal pitch active control strategy,a new pitch angle variable construction algorithm is proposed by analyzing the mechanism of pitch angle on the aerodynamic performance of the fan.With the double disk multiple streamtube model and genetic algorithm,compared to the three kinds of optimization algorithm the new algorithm has the best performance considering with the realizability,the fan performance improvement,the searching efficiency.The new algorithm has practical application value.Because the new pitch optimization algorithm significantly improves the searching efficiency,it is possible to combine CFD numerical simulation technology to get the best pitch angle,and the pitch angle automatic optimization platform is built.In order to ensure the reliability of the optimization results,the accuracy of the CFD model is verified by comparing with the fixed pitch wind tunnel test results.Optimize the pitch angle of two density fan in a plurality of tip speed ratio,the results showed that the at low tip speed ratio,the greater of the density the smaller of the optimal pitch angle amplitude;at the high tip speed ratio,the greater of the density the greater of the optimal pitch angle amplitude.At the same time,the optimal pitch angle curve is strongly related to the tip speed ratio.Based on the optimal active pitch control strategy,the design principle of the passive pitch control device is put forward,and two passive device models are proposed.The time stepping method is used to solve the blade pitch angle in the fan rotation.The key design parameters of the passive device are optimized by genetic algorithm,and the effectiveness of the passive device is verified by comparison.