葉片小翼幾何外形對小型水平軸風力機噪音之影響

Study on the influence of blade winglet geometry on the noise of a small horizontal-axis wind turbine

江承宥(Chen-Yu Chiang)

指導教授 ： 翁輝竹

中原大學/工學院/機械工程研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800385

摘要

本論文完成葉片小翼對小型水平軸風力機噪音之影響。在不考慮機械振動的情況下，主要目的在探討相同尖端速度比下，改變葉片小翼的幾何外形對於小型水平軸風力機的整體聲壓級(overall sound pressure level，OASPL)與轉換效率之影響。首先以NACA 0012作為本研究之基本翼形，並以3D繪圖軟體Pro/E來繪製整體風力機外形，最後再以ANSYS-Fluent軟體進行流場與聲場的模擬與分析。在流場模擬部分，使用SST k-omega紊流模型來求解暫態Navier-Stokes方程式進而得到流場資訊。接著使用FW-H方程式(Ffowcs Williams and Hawkings equations)來取得聲場資訊。本研究藉著改變葉片小翼之幾何外形，探討當改變葉片小翼之深寬比、梢根比及傾斜角對於小型水平軸風力機噪音生成與轉換效率之影響。
研究結果發現，針對主葉片而言，改變其長寬比對於小型風力機的噪音與轉換效率之影響相較於改變攻角大上許多。在葉片小翼部分，改變葉片小翼於受壓側之深寬比對於風力機噪音的影響不大，但對於轉換效率會有一定的影響；於低雷諾數時，會有最佳轉換效率，致使其有最高混合性能參數，但並非增加葉片小翼就有較佳的性能表現。此外，於吸入側改變葉片小翼之深寬比時，會有最低的噪音值。接著，不管在受壓側或吸入側改變葉片小翼梢根比皆會提高風力機的噪音。但在某些情況下，其轉換效率會高於原先設計，故或許在不考慮噪音的情況下，可以考慮改變小翼之梢根比來提升其轉換效率。最後，針對葉片小翼之傾斜角而言，以90 為基準，增加或減少其角度皆會造成噪音上升且轉換效率降低。後續可以藉由上述結果進一步去找到葉片小翼之最佳設計。

關鍵字

葉片小翼，幾何外形，風力機噪音，CFD模擬

並列摘要

This study is conducted to examine the effect of blade winglet on the noise of a small horizontal-axis wind turbine. The main purpose is to investigate the influence of changing the winglet geometry (such as aspect ratio, taper ratio, and cant angle) on its overall sound pressure level (OASPL) and energy conversion efficiency. At first, we use NACA 0012 airfoil as the wind turbine main blade in this study and then simulate the flow and sound field by using ANSYS-Fluent. In the part of flow field simulation, we use SST k-omega turbulence model to solve Navier-Stokes equations and obtain the flow field information. In the part of sound field simulation, we use FW-H equations to acquire the pressure fluctuation values in far-field so as to obtain the OASPL.
Results show that, changing the main blade’s aspect ratio would lead to large variations on OASPL and conversion efficiency. In the part of winglet, changing the winglet’s aspect ratio facing to the pressure side wouldn’t cause large variations on OASPL, but the best conversion efficiency could be found in a low Reynolds number. On the other hand, changing the winglet’s aspect ratio facing to the suction side could lead to the lowest OASPL. Regardless of changing the taper ratio facing to the pressure or suction side, the OASPL may increase and in some designs, the conversion efficiency may increase. Finally, changing the cant angle would lead to lager OASPL and lower conversion efficiency. Above that, we could design the wind turbine blades with lower noise and better performance.

並列關鍵字

blade winglet geometry ； wind turbine noise ； conversion efficiency ； CFD simulation

參考文獻

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