Performance Study Of A5kW Vertical-Axis Wind Turbine

5kW vertical-axis wind turbines belong to small and medium-sized wind turbine. It can serve as an independent system to supply personal family of electricity and heat, and can be used as a freestanding technical facilities used for urban lighting, etc. Also can set up a grid connection for rural power stations and other fields, help reduce electricity bills. Now, the study of the vertical axis wind turbines in our country is still in its infancy. But in recent years small and medium-sized wind turbine is more and more get the attention of many scholars.The study of this topic is about a5kW vertical-axis wind turbine rotor parameters design, rotor aerodynamic performance prediction, numerical simulation and the whole wind turbines simulation, etc. The main contents include the following aspects:First of all, summarizes some theoretical knowledge of the design of vertical-axis wind turbines. Mainly introduced the more accurate aerodynamic calculation theory which is called Double-Multiple Streamtube(DMS) model. Generalize the important formula derivation of the DMS model. By the theory of the vertical axis wind turbines5KW vertical axis wind turbine rotor is preliminary designed. And analyze and research turbine rotor by Double-Multiple Streamtube. Some conclusions are drawn:Firstly, three blade vertical axis wind turbines can get higher power factor, but in areas of high power factor is smaller, and the power coefficient of the second blade vertical axis wind turbines is low, but in the scope of the high power coefficient is bigger. Secondly, the substantial effect of the upwind half-cycle of the rotor with respect to the contribution from the downwind zone for the full range of the tip speed ratios λ≥3is very obvious. The peak power coefficient in upwind area is generated by high tip speed ratio condition, and it in downwind is generated by low tip speed ratio. Thirdly, because of the change of the induced velocity, the normal force and tangential force coefficient of the three blades vertical-axis wind turbines is different as the different location (in the upwind or in the downwind). The aerodynamic load in the upwind is bigger, and in the downwind is small. Fourthly, there is a serious flow retarding effect between the upwind and the downwind, and a serious flow retarding effect enhance with the increase of rotor solidity. It is more obvious in the downwind areas.Secondly, make a2-D numerical simulation of the airfoil of a5kW vertical-axis wind turbine, and model and mesh the two-dimensional wind field by the ICEM software. Again make two-dimensional unsteady numerical simulation of the wind field of a5kW vertical-axis wind turbine by using sliding mesh technology in FLUENT software. Through the analysis of the results of the numerical simulation, some conclusions are drawn:Firstly, there was not boundary layer separation and stalling phenomenon before ten degrees for NACA0018, but we can clearly see the boundary layer separation and stalling phenomenon at15degrees. Secondly, the lift coefficient of NACA0018increase gradually from0degree, and peaked at around12degrees (which is called stall point), then it decreased; There are some error between the simulation data and experimental data about the drag coefficient, but the overall trend is consistent. Thus the calculation of the differential resistance by the CFD software is more accurate, and the calculation of the frictional resistance also exists some problems which is needed to solve. The CFD software can not well simulate the change of the resistance. Thirdly tip speed ratio is one of the important factors which affect the wind turbine power coefficient. Fourthly, under the condition of the low tip speed, we can see clearly the vortex shedding phenomenon, so that this phenomenon reduces the lift-to-drag ratio, decreased the power of wind turbine.Finally, this paper established a mathematical model of a5kW vertical wind turbine rotor. And make the rotor model in MATLAB/SIMULINK. Establish the wind turbine model with turbine rotor, wind speed, transmission system, speed control system. The output characteristics of this wind turbine is analyzed. Some conclusions are drawn:MATLAB/SIMULINK software can well simulate the characteristics of the whole wind turbine. And the parameter selection in the speed controller of kp and kt should not be too big and too small.