Aerodynamic Character And Flow Field Analyzation Of Vertical Axis Wind Turbine Under The Several Typical Conditions

The wind resources as a kind of renewable clean energy has been focused widely by all over the worlds. Wind power in China is the third largest energy after hydropower and thermal power, as Liu yong reported, wind power generation technology will be attention and further development in the12th five-year plan of our country. Vertical axis wind turbines(VAWT) is typical small wind turbines, it has irreplaceable advantages,for example:not adjust blade of wind to face wind direction, simple structure, can be used in the residential district of the city. Researcher are still to do a lot of study to further improve the VAWT’s wind energy utilization.In this paper, the H type vertical axis wind turbines(H-VAWT) as the research object, the aerodynamic characteristics of VAWT and the system to do further research.H-VAWT belongs to lift wind machine. Because its structure and working environment, H-VAWT usually run in under the environment of low wind speed, and the downwind turbines is still working in the trailing vortex of upwind turbines, as well as the influence of the blade tip vortex, so the whole inside flow field and flow field of near the wind turbine is very complicated in the H-VAWT. Therefore, this article base on the independent research and development of the airfoil to numerical simulation with3D and2D models respectively, lift-to-drag performance of self-developed airfoil is analyzed when happened post-stalled; the performance of H-VAWT under the low speed; Moment of inertia and the different tip vanes on influence of H-VAWT is discussed, the main content includes:1. To independent research and development airfoil of H-VAWT as the research object, adopting the URANS, LES, DES three different turbulence models to unsteady calculation in FLUENT software, the comparative study lift drag performance and the distribution of flow field of the airfoil when happened post-stalled. The result showed that the post-stalled static Angle of attack of the airfoil is30°,the original model post-stalled Angle of attack is33°, compared to the original model significantly improved; When the Angle of attack of the airfoil is less than the static stalled Angle of attack, the performance of the lift and drag is close to the original model of the test results by using three kinds of turbulence models simulated;After the airfoil post-stalled, DES turbulence model simulation results not only has a certain reliability, but also can capture the vortex flow around the airfoil;2. Based on independent research and design of airfoil H-VAWT as the research object, and adopting the numerical simulation methods to analyzes the aerodynamic performance characteristics and three-dimensional effect of H-VAWT in the low wind speed condition. Analysis results show that in the low wind speed area, the tip speed ratio unchanged, change the rotational speed or change wind speed, the impact on the performance of the H-VAWT is very big, so when the design and selection of H-VAWT, not only guarantee reasonable tip speed ratio, but also pay attention to the actual situation of wind speed and rotational speed; In numerical simulation, wind speed and setting a reasonable speed for the reliability of the simulation results; The internal flow field effects the simulation results.3. Base on a single blade NACA0012airfoil H-VAWT as the research object, and adopting the method of the numerical simulation to analysis two different conditions blade surface pressure distribution and tip vortex of H-VAWT that are installed three different kinds of tip vanes on both ends of the blade and not installed. The results show that the installed tip vanes can improve the maximum torque coefficient of H-VAWT, especially, the start torque of H-VAWT can be improved when installed Winglet; Installed tip vanes takes advantage of eliminating tip vortex; Compared with other two kinds of tip vanes, installed Winglet on the ends of H-VAWT blade is the more well effect; the lift-to-drag coefficient ratio is little effect for installed tip vane on the blade of H type vertical axis wind turbines, but the lift-to-drag ratio is increased for Winglet at the0°azimuth Angle; tangential force coefficient and normal force coefficient is larger influence for installed V type tip vane and winglet, especially winglet is installed; its have potential to improve the performance of H type vertical axis wind turbine by optimizing geometric parameters and installation Angle of winglet.4. The main performance(out power、out power coefficient、torque、torque coefficient) of straight blade VAWT will be impacted by moment of inertial.This article will analyze that moment of inertial how to impact performance of H-VAWT by utilizing program of Matlab and theory of Double-Multiple Streamtube. The result showed that the max out power coefficient was impacted barely when moment of inertial was changed beyond a litte of range, but lesser moment of inertial s VAWT need major wind velocity when get point of the max out power; lesser moment of inertial s VAWT own major out power coefficient, torque coefficient and out power before get point of the max out power coefficient; out power coefficient and torque coefficient will obviously changed with increasing of wind velocity for VAWT of lesser moment of inertial.5.H-VAWT have camber of blade, there are two methods for blade installed. A kind of is Concave-out Configuration, the other is Concave-in Configuration. This papers mainly discuss the effort for different blade numbers from two kinds of blade installed by using numerical simulation method.The result showed that the pressure is the most obvious at the 90degree azimuth angle for Concave-out Configuration, but the pressure is barely changed at the0degree,180degree and270degree azimuth angle for two kinds of blade installed methods; The torque coefficient is more declined and the turbulivity is more strong with increase of the blade numbers for Concave-out Configuration; At the area of low rate of tip speed,the power coefficient is more bigger for Concave-out Configuration than the Concave-in Configuration’s, and the max power coefficient is bigger,but the power coefficient is will incline than Concave-in Configuration’s when at the area of high rate of tip speed.