計算流體力學應用於風力發電機結構受風可行性研究

A study of applications of CFD for the wind turbine structures affected by wind

劉宗憲(Tzung-Shian Liou)

指導教授 ： 張正興

淡江大學/工學院/土木工程學系碩士班/碩士(2010年)

https://doi.org/10.6846/TKU.2010.00301

摘要

本研究主要是在探討計算流體力學（CFD）軟體應用於風力發電機結構受風影響的可行性。以相同的邊界條件下，比較風力發電機縮尺模型，在數值模擬和風洞試驗中所得的基底剪力和彎矩。藉此找出一套較適合的參數設定，預測實場的狀況。在進行風洞試驗時，因為相似性無法達到實場的情況，所以無法將風力發電機模型受風影響的結果用來預測實場。而且在實場量測時，也面臨諸多的問題和困難。因此將風洞試驗裡的邊界條件，套用到數值模擬的設定中，將兩者以相同條件下得到的結果互相比較。經過反覆測試後，將模擬值與試驗值的誤差降至最低。再將此套數值模擬的參數設定，依照相似性的原理縮放，模擬實際尺寸的風力發電機，以便對實場的預測。

本研究在數值模擬中，透過不同的紊流模式，以滑動網格技術和動態網格技術進行模擬和探討。雖然文獻提到，滑動網格技術可應用在物體旋轉的模擬中，但其模擬的方式是利用分界面上，網格節點與節點之間的連結，進行數值的交互傳遞。而動態網格技術模擬的方式，是透過網格隨著物體移動的情形，進而將計算域整體的網格進行改變或重繪。所以吾人認為利用動態網格技術模擬，更能表現實際狀況。

結果顯示，利用動態網格技術和滑動網格技術的模擬下，動態網格技術所得到的數據較為趨近於試驗值。而在紊流模式為k-epsilon RNG model，使用動態網格技術模擬得到的結果中，My的誤差值較大，約為76.5%。但是在Fx的誤差值較小，約為1.08%。由此可知，以數值模擬分析風力發電機受力的情形，使用動態網格技術會比滑動網格技術更為理想。而實場預測的部份，將模擬的結果以相似性的原理縮小，最後再和縮尺模擬的結果比較。可以得到，Fx的誤差約為15%，而My的誤差約為13.5%。

關鍵字

計算流體力學 ； 風力發電機 ； 動態網格 ； 滑動網格

並列摘要

This study investigated the structure behaviors of the wind turbine affected by the wind by using computational fluid dynamics (CFD) software. The base shear stress and moment of the wind turbine was compared for both results of numerical simulation and wind tunnel test with the same setting. Considering the dynamics similarity between the wind tunnel test and the field measurement, the wind tunnel test preformed with lower rotating speed of the wind turbine than the full scale wind turbine. If a realizable CFD model can be established for predicting the dynamic behaviors of the wind turbine. That will be very helpful for structure designer to get more information about the dynamic behaviors of the wind turbine during design and planning stage of the project.

Both of numerical models of the dynamic mesh and sliding mesh were selected for simulations. The results showed that the dynamic mesh model was better than sliding mesh model by comparing to the wind tunnel test results. In the case of the k-epsilon RNG turbulence model, the prediction of the bending moment affecting by acrosswind was more than 50%, and the prediction of the force affecting by acrosswind was less than 5%. The both simulation results of the small scale and full scale wind turbine obtained by CFD model. Comparisons of result showed that the error of Fx was about 15% and My was about 13.5%.

並列關鍵字

CFD ； Wind turbine ； Dynamics similarity ； Wind tunnel test ； Full scale

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