Numerical Study of the Flow around Wind Turbine to Make Wind Energy Fit for Practical Use

风能是公认的环保型能源，受到人们的广泛关注。事实上，最近风力发电厂的数量增加了。另一方面，我们对干旱地区的环境问题很感兴趣，认为风力可以用来抽水灌溉。一般情况下，横流型风车的扭矩较大，适合于此用途。本研究的目的是对Savonius转子和多个叶片的横流涡轮周围的流场进行数值模拟和可视化，以获得其在运行中的性能，并提出新的设备来提高其性能。采用有限差分方法对这些微分方程组进行积分。为了准确表达转子的形状，采用贴体坐标系。旋转坐标系也被使用，以便自然地包括叶片的旋转。当考虑壁面等非旋转障碍物的影响时，引入了区域分解方法。对大流士风力机等高速风力机的流场进行了数值模拟，验证了数值方法在风力机研究中的有效性，可视化了风力机周围的复杂流动，提出了提高风力机性能的新手段。

The wind force is widely recognized as the environmentally friendly energy and attracts public attention. Actually, the number of wind power plants for electricity increases recently. 0n the other hand, we are interesting in the environmental problems in arid land and considering that the wind force can be used in pumping water for irrigation. In general, the windmill of cross flow type is suitable for this purpose since its torque is large. The objective of the present study is to simulate and visualize numerically the flow fields around the Savonius rotor and the cross flow turbine of many blades, to obtain its performance under the operation and to propose new instruments which can increase its ability.Two and three dimensional incompressible Navier-Stokes equations are numerically solved by the MAC method combined with fractional time step method. Finite difference method is used to integrate these differential equations. In order to express the shape of the rotor exactly, body-fitted coordinate system is employed. The rotational coordinate system is also used so as to include the rotation of the blades naturally. When the effect of the non-rotating obstacle such as the wall is investigated, domain decomposition method is incorporated. The numerical results are compared with experiments and the agreement is satisfactory.The flow field around the high speed wind turbine such as the Darius turbine are also examined by the numerical simulation.The scientific innovations of this research are to have shown the effectiveness of numerical method on the study of wind turbine, to have visualized the complex flow around the wind turbine and to have proposed new instruments which can promote the ability of the rotor.