Numerical Simulation On Aerodynamic Performance Of Magnus Wind Turbine And Exploration Of Airfoil Optimization

As the key equipment which transfer wind energy into electricity, wind turbine has always been the focus of research in the field of wind energy technology. For the blade is the component that complete the energy conversion, so its performance directly impacts the efficiency of wind turbine. The current commercial horizontal axis wind turbine is always with a capacity of MW, which means the length of a single blade reaches tens of meters that leads to a heavy gravity load. In addition, the blade is always twisted to gain a good efficiency which also adds up to the difficulty of manufacturing as well as sensitivity to the change of the attack angle. The current widespread commercial wind turbine operates only when the income velocity is above its cut-in speed which is often 4m/s, so it fails to make a good use of the wind energy in the range of media to low wind speed. However, Magnus effect based wind turbine has a good efficiency in low wind speed region and the geometry of the blade is simple which facilitate the manufacturing process. However, its efficiency is not as high as commercial wind turbines. So it’s quite necessary to understand its flow field and try to find some methods to improve the efficiency.Firstly, this thesis gives a brief introduction to the aerodynamic theory such as actuator disc theory, blade element theory and momentum theory. Then extends the theory and equations to fit in the flow situation of the new Magnus wind turbine and build the aerodynamic model for it.Secondly, this thesis describes briefly the basic principles of computational fluid dynamics. Then utilize the numerical simulation software Fluent to run a simulation of the flow field around the airfoil at different inflow wind velocity and rotational speed. Draw the conclusion that the lift coefficient of two-dimensional flow around a rotating cylinder is proportional to the rotational speed and spinning ratio, and inversely proportional to wind velocity. The lift to drag ratio of the airfoil is relatively high in the low wind speed region.Thirdly, rotors that have different configurations are simulated under different working conditions. This is for the research of the effects of rotor geometry on wind turbine efficiency, upon which can lead to the optimal configuration of the rotor. The results shows that a rotor with 6 blades gains a better efficiency and when the spinning ratio is between 2 to 6 the efficiency can reach 25%.Finally the thesis comes up with an optimization schemes for the 2D airfoil of Magnus effect based wind turbine to improve its poor lift to drag ratio. Explore the feasibility of this method and indicated the direction for further optimization.