Computations of the Unsteady Flows Past Horizontal Axis Wind Turbines Using Body Force Method

• Main Authors: Chun Ko, 柯淳
• Other Authors: Ching-Yeh Hsin
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/67006423626937646801

碩士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 101 === Wind turbine is the most common device to extract wind energy. Among many types of wind turbines, the floating offshore wind turbine, though still in the development stage, has a high potential to become a device to provide economic energy. In order to analyze the unsteady aerodynamic forces of floating offshore wind turbine due to wind and wave, we generally use unsteady RANS methods for unsteady flow calculations. However, it is complicated and time consuming. In this paper, we have developed a body force method based on the actuator sector model which can efficiently compute the unsteady forces of wind turbines in unsteady inflows. In order to confirm the accuracy of actuator sector body force method, we first use this method to compute the flow field of an inclined shaft propeller, and the computational results are compared to the results from a boundary element method. The trends of results from two methods are close. We then apply this method to the computations of wind turbine flow field, and compare the results to those of real geometry by unsteady RANS method. It is found that the selection of time step size is critical to the computational results. Finally, we use actuator sector body force method to compute the flow field of a wind turbine in an oblique inflow, and the results reflect the physical phenomena. In the future research, we hope to extend the present method to different applications, such as analysis of wind farm in unsteady inflow. The comparison of the computational results to the experimental data is expected to confirm the accuracy of this method.