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

风力作为一种环境友好型能源，受到了广泛的关注。事实上，风力发电厂的数量最近有所增加。另一方面，我们对干旱地区的环境问题很感兴趣，并认为风力可以用来抽水灌溉。一般来说，横流式风车由于其转矩大而适合于此目的。本文采用MAC方法结合分数时间步长法对二维和三维不可压Navier-Stokes方程进行了数值模拟，研究了Savonius转子和多叶片横流涡轮机的流动特性，并提出了提高其性能的新方法。用有限差分法对这些微分方程进行积分。为了准确表达转子的形状，采用了贴体坐标系。还使用旋转坐标系，以便自然地包括叶片的旋转。当研究非旋转障碍物（如墙）的影响时，采用区域分解法。数值计算结果与实验结果进行了比较，吻合较好，并对Darius型涡轮机等高速风力涡轮机的流场进行了数值模拟，本研究的科学创新之处在于表明了数值方法在风力涡轮机研究中的有效性，可视化了风力涡轮机周围的复杂流动，并提出了可以提高转子能力的新仪器。

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.