Research On The Aerodynamic Performance Of Small Vertical Axis Wind Turbine

Wind power is converted into electrical energy through the wind turbine device, andthe impeller is the key component of the wind turbine. In design of the impeller of the windturbine, to get accurate dynamic performance for the impeller of the wind turbine is the keyand foundation for the whole and the structure design. In this paper, the research work on500W H-style vertical axis wind turbine, performs the aerodynamic performance andstructure dynamic performance of the impeller. The main contents are as follows:First of all, on the base of aerodynamic designing theory in the vertical axis windturbine impeller, single streamtube model, multiple streamtube model and vortex modelare introduced in detail. And multiple streamtube model theory is chosen to analysis theforces on the wind turbine blades. Also the method of calculating output power and torqueare presented. The results show: the fix radius of the impeller, the number of the blade, theblade chord and the blade height are the main parameters which have great influence onthe output power and torque of the vertical axis wind turbine impeller.Secondly, H-style vertical axis wind turbine of which the output power is500W ischosen as the research object. The orthogonal experiment optimization designmethodology is applied. The fix radius of the rotor, the number of the blade, the bladechord and the blade height are selected as the four main factors, and the power of theimpeller is selected as the performance target. Obtained an optimal solution, and the trendof influence which the change of factors level on the output power of the impeller. Theresults show: the number of the blade is the significant influencing factor which affectsoutput power of the H-style vertical axis wind turbines impeller. The output power of theimpeller can be impoved by controlling the number of the blade.Thirdly, The numerical simulation on unsteady rotated flow of a H-style vertical axiswind turbine impeller is done by means of the software FLUENT. First,Two-dimensionalmodel of the impeller is built, and then model is meshed, boundary conditions is identified,at last equations are solved. The velocity distribution regularities of the flow among thedifferrent position angle, different position of one blade and different incoming windvelocity are compared. The results show: The flow field around the impeller presentunsteady absolutely. The flow flied is different in different position of one period. Rotatingin one period, the flow field around the airfoil of a single blade is changed periodically. The flow field in different wind speed conditions are not the same either.Finally, the modal analysis of the impeller is done by the finite element softwareANSYS on the basis of the rotor dynamics theory. The dynamic equations are solved byLanczos method. The natural frequency and vibration mode are carried out when theimpeller is static. Obtained the natural frequences at each order in different rotating speed,and the Campbell diagram about the relationship between natural frequences and excitedfrequences during the impeller operation. The results show: Bending vibration is the mainvibration on the impeller. As the working speed is below the critical speed and avoided theresonance area, the impeller can work safety.