Study On The Influence Of Configuration Parameters On The Aerodynamic And Wake Characteristics Of A Double Vertical Axis Wind Turbine

Wind power is a free renewable energy source that does not pollute the environment.The utilization of wind energy can effectively reduce the consumption of fossil energy and greenhouse gas emissions,so it has received more attention than ever before,among which wind power generation is the main means of wind energy utilization,because the vertical axis wind turbine has simple structure,low noise,easy maintenance and good performance in high turbulence area,Therefore,this paper takes vertical axis wind turbine as the research object to study aerodynamic performance and wake characteristics of wind turbine.By verifying the model,grid and turbulence model of a single wind turbine,the optimal model is selected,and the simulation results are compared with the experimental data to verify the accuracy of the simulation.Research on aerodynamic performance of a single wind turbine shows that:With the increase of blade tip velocity ratio,more and more air flow cannot pass through inside the wind turbine,and the only way to choose is to flow around it.The wake of a single wind turbine tends to diffuse in the windward direction,and the diffusion range is within the upper and lower 1D horizontally.In addition,with the increase of blade tip velocity ratio,the wind turbine’s near-wake velocity loss is increasing.Meanwhile,in the far wake region,the wake recovery speed gradually increases with the increase of tip velocity ratio.In order to study the flow field characteristics of the vertical axis wind turbine,based on the single machine research,the control variable method was introduced to study the aerodynamic performance of the double vertical axis wind turbine system based on the factors affecting the system performance.A free combination of four factors under different levels was designed,and the optimal and worst conditions were obtained as follows:?=2.5,RT=(-,+)reverse rotation,l=1.7 D,?=30°and?=1.5,RT=(+,+),l=1.7 D,?=90°.In addition,four factors affecting the power output of the system are put forward in the following order:wind direction>tip speed ratio>spacing>spin direction.The effect of single factor on system performance is reflected in the following aspects:the effect of tip ratio on system aerodynamic performance is mainly through the significant extension of torque in the late upwind path;The influence of wind direction Angle on performance is mainly due to the influence of upstream wind turbine clogging.In particular,the high velocity on the side of upstream wind turbine contributes to the peak c_p of downstream wind turbine.The influence of rotation on system performance is mainly through inhibiting the upwind path y velocity,thus changing the pressure difference on both sides of the blade to increase,which is more conducive to the generation of lift and torque.Then,based on the influences of the four factors on the aerodynamic performance of the system,the influences of the spacing on the wake characteristics of the system are described as follows:when the spacing is small,the wind acceleration effect of the clearance is better,and the larger spacing presents better turbulence recovery.The influence of spin on wake is mainly shown as follows:the homologous wake is asymmetrically distributed relative to the center line,while the contra-spin system always maintains a symmetrical pattern.Moreover,due to the transverse flow movement,the wake width of the contra-spin system is always larger than that of the homologous system,which can be up to 0.5D larger.Therefore,the contra-spin system has a more compact wake.The impact of tip velocity ratio on wake flow is mainly manifested as follows:with the increase of tip velocity ratio,the near-wake velocity deficit becomes larger;in the far wake region,with the increase of tip speed ratio,the downstream wake recovery becomes faster.A larger tip velocity ratio is more conducive to wake recovery,but a relatively small tip velocity ratio provides a greater spatial choice for the wind turbine rear spreader.The influence of wind direction on wake is mainly manifested as follows:overall,the velocity distribution is"M"shape.When the wind direction is arranged side by side,the wake velocity loss is the largest,about 0.25U0,while when the wind direction is arranged at 60°,the wake velocity loss is the smallest,only 0.1U0.