Research On The Declination Variation And Achieve Mechanism Of Vertical Axis Turbine

As a kind of tidal current energy generation device, the vertical axis turbine has lots of advantages, such as simple structure, no selectivity for flow direction, easy to install and maintain. Experiments and studies indicate that the pitch system plays an important role for improving the output performance of vertical axis turbine, although the energy capture efficiency of vertical axis turbine has to be improved in the future. Based on the studies of performance of the established optimization model and the variable propeller pitch structure for variable-angle vertical axis turbine, the blade declination variation and the mechanism which can realize it have been studied in this paper.The effect of rotation rate of turbine and induced velocity on the lift and drag coefficient values have been consummated, and the main affecting factors for the performance of vertical axis turbine and the performance of different declination variation have been analyzed.An optimization mathematical model for the vertical axis turbine performance has been proposed, in which the instantaneous torque coefficient and the blade attack angle are respectively selected as the objective function and design variable. By solving this model, one can obtain the optimum attack angle and declination sequence for stationary tip speed ratio.Meanwhile,by taking out the trigonometric fitting function and analyzing the turbine fluid model based on the declination sequence.The trajectory of VSP (Voith Schneider propeller) Linkage has been designed based on the optimal declination law. The best sizes parameters combination of the six-bar linkage with two cracks has been solved under stationary speed ratio. The displacement regulation scheme for variable speed ratio has been taken out by analyzing the rack control mechanism with double degree of freedom.The simulation model for the declination regulation mechanism which has been designed on VSP mechanism has been established, and the turbine impeller working condition and performance has been analyzed under different flow rates and density parameters by CFD method.