微型風力發電機外罩與葉片效應之空氣動力特性探討

Investigation of aerodynamics characteristics of micro wind turbine with different flanged diffuser and blades

洪呈緯(Cheng-Wei Hung)

指導教授 ： 陳增源

淡江大學/工學院/航空太空工程學系碩士班/碩士(2012年)

https://doi.org/10.6846/TKU.2012.00015

摘要

本研究主要探討微型水平軸風力發電機在擴散外罩下，匹配不同的葉片的空氣動力特性。首先，以數值模擬軟體FLUENT探討擴散外罩數值，結果顯示，以擴散角度30度、入口直徑30公分、長度10公分的擴散外罩可以增加空氣的流速50%，另實驗結果顯示將此擴散外罩安裝在上底20.5公分，下底46.5公分，長50公分的擋風罩上，可得到最佳的功率輸出。
本研究以製作平板葉片為主，選擇較易加工、材料韌性足夠之工程塑膠-MC尼龍板為材料。首先探討轉子(直徑30公分)在擴散外罩的不同位置其增益效應，而後以不同螺距角度與不同的葉片葉根與葉尖比例Cr/Ct作比較；結果顯示，轉子置放在擴散外罩中間，螺距角度為30度以及Cr/Ct為0.3時，大幅提升功率和扭矩輸出。
本研究另改變葉片之阻塞比以及葉片數來提升整體的功率和扭力輸出；以相同阻塞比，葉片數為6、8、12三種組合作比較，結果顯示以8葉片為選擇；又以相同之8葉片，阻塞比為40%、50%、60%、70%四種組合作比較，結果顯示以60%在功率輸出有最佳效果。從本研究可得到在微型風力發電機中，葉片大翼尖的設計以及阻塞比有其重要性。

關鍵字

微型水平軸風力發電機 ； 非扭轉葉片 ； 翼緣擴散外罩 ； 風洞實驗

並列摘要

Abstract:
This thesis investigates the aerodynamic characteristics of micro, horizontal-axis wind turbine with different flanged diffusers and blades. First, a numerical study using FLUENT was conducted to investigate the flow field inside the flanged diffusers. A flanged diffuser with inlet diameter of 30 cm, length of 10 cm and diffusion angle of 30o was used for this purpose. Results show that the flow accelerates by 50% inside the flanged diffusers. Experimental study shows that a better power output can be achieved when installing the flanged diffuser inside a wind shield of 50 cm height, 20.5 and 46.5 cm top and bottom widths, respectively.The blades applied in this thesis are large-tip, non-twisted due to easily machined. The experimental studies were conducted in a wind tunnel system to obtain the relations between the power coefficient (CP) and tip speed ratio (TSR), and between the torque coefficient (CT) and TSR.
Effects of the rotor position inside flanged diffuser, rotor solidity and blade number on rotor aerodynamic performance are investigated. The blade cross-section is NACA4415 airfoil. The pitch angle of the blades is fixed at 30°, and the chord length ratio between the blade root and tip is fixed at 0.3. Results show that larger power output is obtained when the rotor positioned approach the diffuser inlet. The larger the blade number is, the higher the power output is, but the difference is limited. In general, the 60%-rotor solidity achieves a better power output. Comparisons between the present and previous blades show that non-twisted, large-tip blades have better power and torque coefficients, and achieve the larger power output at lower rotor rotational speed. This result provides some important information in blade design of micro-wind turbines.

並列關鍵字

Micro wind turbine ； flanged diffuser ； solidity ； wind tunnel test

參考文獻

[13]瑞領科技股份有限公司，LW-3840大型風洞使用手冊。

[5] T. Matsushima, S. Takagi, S. Muroyama, “Characteristics of a highly efficient propeller type small wind turbine with a diffuser”, Renewable Energy, Vol.31, 2006, pp.1343-1354.

[6] K.I. Abe, M. Nishida, A. Sakurai, Y. Ohya, H. Kihara, E. Wada, K. Sato, “Experimental and numerical investigations of flow fields behind a small wind turbine with a flanged diffuser”, Journal of Wind Engineering and Industrial Aerodynamics , Vol.93, 2005, pp.951-970.

[7] Y.Ohya,T. Karasudani,A. Sakurai,K.I. Abe,M. Inoue, “Development of a shrouded wind turbine with a flanged diffuser”, Journal of Wind Engineering and Industrial Aerodynamics,Vol.96, 2008, pp.524-539.

[8] F. Wang, L. Bai, J. Fletcher, J. Whiteford, D. Cullen, “The methodology for aerodynamic study on a small domestic wind turbine with scoop”, Journal of Wind Engineering and Industrial Aerodynamics , Vol.96 , 2008, pp.1-24.