在風力發電機中,葉片是很重要的元件,葉片負責把大自然中的風能轉換成轉動的機械能,其性能對於整個風力發電機系統效率影響很大,因此研究如何獲得葉片在流場中的表現成為一個重要的課題。 本研究利用CFD分析軟體,針對垂直軸式風力發電機葉片流場提出一套有效的數值模擬方法,可以同時適用於Savonius型以及Darrieus型兩種主要垂直軸式葉片。對於葉片流場紊亂狀況進行觀察探討,根據分析結果,使用二維暫態之大尺度渦流模擬可成功模擬出Savonius型葉片的效能趨勢,透過三維LES暫態模擬Savonius型葉片Cp模擬與實驗誤差為3%以下。在Darrieus型葉片研究部分,使用LES二維暫態模擬亦可正確模擬葉片的效能趨勢,證實本研究所提出之方法可有效模擬垂直軸式風力發電機葉片之流場變化,可以用在未來改良設計之參考。 在實測方面,利用自行設計製造的風洞,進行風洞量測實驗,先校正測試段的風速,再進行垂直軸式風力發電機葉片之風洞實驗,成功驗證風洞實驗的準確性,並獲得風機的數據及特性。
Wind turbine blades play an important role to convert wind energy into mechanical rotation. Blades design has a tremendous influence on the efficiency of wind turbines. Therefore, this thesis addresses an important question of how to obtain the blades performance in flow field. CFD was used in this work to simulate flow field, and provide an effective way of numerical simulation which is suitable both for Savonius-type and Darrieus-type Vertical Axial Wind Turbine (VAWT). Starting with observing and analyzing the blade’s disordered flows, the Savonius-type blades’ efficiency trend is able to be obtained by using two-dimensional of large eddy simulation. Moreover, the error of the value of Cp comparing to the experimental results is capable to reach below 3% by 3D LES simulation. In the study of Darrieus-type blades, the blade’s efficiency trend being accurately predicted by utilizing 2D LES simulation verifies that the method provided in this thesis is capable to effectively simulate the changing in the flow field of the VAWT blades. This simulation based modeling methodology can be used to design and improve wind turbines’ performance in the future. For experimental verification, a wind tunnel was designed and constructed to conduct the VAWT’s wind-tunnel testing. The first step was to adjust the testing wind speed, and then conduct the VAWT’s wind-tunnel testing. Data and characteristic of the wind turbine were obtained while the wind-tunnel testing was successfully verified.