Investigation On The Finite Element Analysis And Optimization Of The Blade Structure Of The Vertical Axis Helical Blade Turbine

Ocean tidal energy has the characteristics of wide distribution,regularity and high energy density.It has become one of the most important green renewable energy that can be used by human beings.However,there are few related optimization theories about how to improve the hydrodynamic performance of the vertical axis turbine by optimizing the shape variation of the blades used to collect the tidal current energy.In this paper,the optimization of the structural parameters of the blades of the vertical axis hydraulic turbine is studied.After the overall system scheme of the turbine is put forward,the two-dimensional hydrodynamic analysis of the blades of the turbine is carried out.On this basis,the shape of the blades is helicalized,and the optimization and comparative test of the relevant structural parameters are completed.The purpose is to solve the shortcomings of the traditional vertical axis turbine,such as poor self-starting performance,violent dynamic torque fluctuation and low energy capture efficiency.The complex relationship between the structural parameters of the turbine blades and the hydrodynamic performance of the turbine is revealed,and the optimization potential of the structure of the vertical axis turbine blades is explored to a large extent.The scheme of the floating helical blade turbine system is proposed,and the names and functions of the structures in the system are explained.The basic parameter formulas of the numerical calculation of the turbine are quoted,and the control equation,solution algorithm and sliding mesh theory of the numerical simulation are analyzed.The hydromechanical structure dynamics calculation theories such as fluid structure coupling and wet modal theory are studied.Based on the fluent numerical simulation platform,the airfoil parameters of the vertical axis turbine are calculated,compared and optimized,and the flow field of the selected airfoil at different angles of attack is analyzed.The two-dimensional CFD simulation model of the turbine blades is established,the pre-processing,flow field setting and simulation calculation of the model are completed,and the hydrodynamic state results of the turbine blades in the simulation flow field are obtained.In view of the number of blades,flow field velocity,impeller radius and chord length of blades of the turbine,the flow field state and hydrodynamic performance of the turbine under different parameters are obtained,thus the analysis and optimization of the two-dimensional property parameters of the turbine blades are realized,and the influence relationship between different blades parameters and the hydrodynamic performance of the turbine is revealed.The concept of helical variation optimization of turbine blade structure is introduced.Based on FLUENT software,the three-dimensional CFD numerical simulation of helical blade group is carried out,and the three-dimensional model building,mesh setting and parameters solving are completed.The results of three-dimensional flow field of helical blade turbine group are obtained.Aiming at the three-dimensional property parameter variables such as the helical span angle and height-to-diameter ratio of the turbine blades,multiple sets of simulation control tests are set up to compare and analyze the dynamic torque state,self-starting performance,energy capture efficiency and flow field state of the turbine under different blades structure parameters.The effects of different three-dimensional blades structural parameters on the hydrodynamic performance of the hydraulic turbine are obtained through the hydrodynamic performance of the flow field state.Through the ANSYS Workbench,the module group of modal analysis based on fluid structure coupling is built.The operation of the calculation domain of the external flow field of the turbine blades,the coupling of the load in the flow field domain and the structural domain of the blades,and the calculation of the structural modal of the blades are completed.The natural frequency and the corresponding modal results of the helical blades are obtained.Meanwhile,the Campbell rotor analysis method is used to capture the rotational speed data of blades group that could cause structural resonance phenomena,so as to realize the analysis and research on the vibration characteristics of blades group under working conditions.In this paper,the research on the blade structure parameters of the vertical axis helical blade hydraulic turbine improves the torque output state of the blades group and the hydrodynamic performance of the hydraulic turbine system.At the same time,the test results and conclusions obtained in this paper can provide data support for the design and optimization of vertical axis turbine blades group structure,which has a very broad application prospect and practical significance in engineering.