Research On Effect Of Frustum-shaped Wind Collector Equipment On Starting Performance And Output Power Of Vertical Axis Wind Turbine

This study is committed to design a frustum-shaped wind collection pattern installed upper and lower ends of Straight-blade Vertical Axis Wind Turbine, the purpose of which is to improve the starting performance under low wind speed and output power of SB-VAWT. The principle of it is using the channel with variable cross-section formed by wind collection pattern to collect fluid, improve the wind speed inflow, reduce flow loss of blade tip and rectify flow field inner, thus the static starting performance and dynamic power output performance is improved. Theoretical analysis, numerical simulation and wind tunnel experiment are used conjunctively in this study, and the two major parts of the research content can be summarized as follows:(1)Theoretical analysis and numerical simulation are combined to study the effect of frustum-shaped wind collection pattern on static starting performance. Firstly, using theoretical analysis method to analyze the principle of wind collection based on principle of fluid mechanics, then the structure shape was set preliminarily; Afterwards, quadratic orthogonal rotating combination design method and three-dimensional numerical calculation method were combined to optimize design the structural parameters of wind collection pattern through analyzing, for which the static starting torque was calculated while the wind collection pattern was combined by variable structural parameters to obtain the most optimal ones; Finally, the mechanism of wind collection pattern was revealed after comparison and analysis on flow field around rotor relatively, which was installed with wind collection pattern or not.(2)Wind tunnel experiment was used to research the effect of frustum-shaped wind collection pattern on dynamic output power performance. For which, the most optimal wind collection structure was designed and produced on account of the simulation result, a SB-VAWT whose diameter is 600 mm and height is 500 mm, and frustum-shaped wind collection pattern were manufactured. The wind tunnel experiment was conducted on the structure to verify the validity of it, through which the speed characteristics and output power performance of wind turbine(with variational blades) with wind collection pattern or not under different wind speeds.The following main conclusions under the experimental conditions can be obtained:(1)A set of structure parameters of wind collection pattern were get in allusion to the wind turbine model in present research by numerical simulation, which could improve the static starting performance effectively, the parameter combination is that the angle of wind collection pattern is 46 degrees, the height is 299 millimeters, the distance to rotor is 36 mm. The results of wind tunnel experiment show that the stating torque at different rotation angles of wind turbine with wind collection pattern is improved in different extent, and which has been increased by 30% while rotation angle is 15 degrees. Meanwhile, the starting time of wind turbine with wind collection pattern is shortened, whose rotation speed grows quicker and stabilized speed is higher, from which, the impact of frustum-shaped wind collection pattern on improvement of starting performance is proved to be effective.(2)The results of dynamic performance experiment of wind turbine with or without wind collection pattern show that the maximum output power coefficient of wind turbine with wind collection pattern is increased at different wind speeds in different extant, and it is increasing with the increase of wind speed, which has been upgrade up 35 percent. The results also indicate that the wind collection pattern has certain effects to wind turbine performance no matter it has two blades or four blades, which also explains that that the effect of wind collection pattern to SB-VAWT with different blade numbers is applicable.(3)By analyzing the three-dimensional flow chart and velocity distribution on different planes obtained through numerical calculation, the effect of wind collection pattern to the entrance of wind rotor is obvious, the highest wind speed is increased by 36.7%; The wind collection pattern has a certain influence on vortex of blade tip and inner wind rotor, then in some extant energy loss has been reduced, thus the flow field characteristics around wind turbine is improved.Calculation and experiment were combined to prove the effectiveness of frustum-shaped wind collection pattern to starting performance and output power of SB-VAWT, which provides a research basis to exploit wind collection pattern with compact structure and high efficiency, and provides the beneficial exploration for developing that with high performance. The methods of numerical simulation and orthogonal rotating design will provide reference for the design of vertical axis wind turbines with similar structural parameters.