Simulation Study On Aerodynamic Characteristics Of Verticalaxis Wind Turbine With Drag-disturbed Flow Device

With the full advance of the "14th Five-Year Plan" of modern energy,in order to achieve the "carbon peak" and "carbon neutrality" of the double carbon goals,renewable energy has become the key development object of the energy industry.Wind energy,as one of the abundant renewable energy sources,has been developed in recent years.How to improve the efficiency of wind energy is the focus of the research.Due to the off-grid and distributed characteristics of small and medium-sized wind turbines,attention is gradually paid to the vertical axis wind turbine with linear wing lift,because of its advantages such as simple structure and no need to yaw to the wind.However,the disadvantages of poor starting performance and lower wind energy utilization coefficient than horizontal axis wind turbine have been restricting the development of vertical axis wind turbine with linear wing lift.In this study,a vertical axis wind turbine equipped with drag spoiler was proposed based on the conventional lift-drag combined vertical axis wind turbine.The wind turbine structure consists of an outer straight wing lift blade and an inner one installed at the maximum thickness of the lift blade.At low tip ratio,the device opens to form drag blade,and at high tip ratio,the device closes to form turbulence blade.The start-up performance and wind energy utilization coefficient of vertical axis wind turbine with linear wing lift are improved.The main research contents are as follows:Firstly,three drag-disturbed flow devices are designed,which are NACA0018 airfoil commonly used for lift blade,triangle when the spoiler plate is deployed,and semi-ellipse commonly used for drag vertical axis wind turbines.Then,different wind turbine models are divided into grids.The numerical simulation software is used to calculate the three schemes under the condition of flow field with wind speed of 8m/s.The results show that: Vertical axis wind turbines installed with drag-disturbed flow device will improve the performance of wind turbines in the state of drag blades,while in the state of turbulence blades,only vertical axis wind turbines installed with NACA0018 airfoil drag-disturbed flow device will improve the overall performance of wind turbines.Overall,the vertical axis wind turbine installed with NACA0018 airfoil drag-disturbed flow device has the best lifting effect,and the average wind energy utilization coefficient increases by 11.2%.Secondly,the post-processing software is used to analyze the blade tip ratio of 0.4 and 2,and the wind turbine at the azimuth of 80° and 250° to obtain the vortex,pressure and velocity streamline nephogram.The results show that with low tip ratio,the negative torque of the semi-elliptical resistance blade can be effectively reduced because the convex surface is blunt,followed by the NACA0018 airfoil resistance blade,and the negative torque of the triangular resistance blade is the largest.In the case of high tip ratio,NACA0018 airfoil spoiler blades can provide lift while compensating for lift loss of outer blades,followed by semi-elliptical spoiler blades and triangular spoiler blades with the worst performance.Finally,the structure design and three-dimensional modeling of the drag-disturbed flow device are carried out to provide a model reference for the real machine test.To sum up,the model establishment,grid division,numerical simulation,post-processing analysis and device conversion structure design of the proposed vertical axis wind turbine installed with drag-disturbed flow device are carried out in this study,and the aerodynamic performance laws of the vertical axis wind turbine with this structure are obtained,which provides a reference for the design and practical application of wind turbine.