本研究中使用雙向流固耦合的數值方法，對完整的NREL 5MW型離岸風機在額定風速(11.4 m/s)和固定轉速(12.1 rpm)的條件下，進行該風機的氣動力特性預測和評估。風機周圍不可壓縮流場計算，是基於求解納維爾史托克斯方程組及k-Omiga紊流模型，利用有限體積法進行控制方程式數值離散，計算過程中採用滑移網格方式模擬風機葉片的旋轉運動。本研究在流固耦合計算中，使用Abaqus計算考慮複合材料特性的葉片變形，使用STAR-CCM+以滑動網格方式模擬葉片的轉動行為，同時進行葉片流固耦合所需資料的映射與傳遞。本研究採用弱耦合的方式處理流固耦合界面，以及運用重新生成網格的方式替換包含葉片之流場網格區塊，以反映葉片變形對於流場的影響。本文分別對剛性和彈性葉片兩種情況進行風機的氣動力特性計算，本研究使用旋轉坐標方式進行流固耦合計算以獲得彈性葉片的穩定變形位置。本研究的計算結果顯示，葉片參考點的平均變形量約為葉片總長度的6.45%左右。與剛性葉片結果相較，考慮葉片變形的風機整體功率輸出下降約9.56%。

This study predicts the aerodynamic performance of the NREL 5MW offshore wind turbine via a two-way fluid-structure Interaction (FSI) approach. This simulations are performed under the rated wind velocity 11.4 m/s and rated rotor speed 12.1 rpm at full scale. The flow field around the wind turbine is computed by solving the Navier–Stokes equations incorporated with the k-Omiga turbulence model, where air is assumed as an incompressible viscous fluid. The equations are discretized using a finite volume method. In this study STAR-CCM+ and Abaqus are employed to solve the FSI problem, where a weak coupling approach is used. A remeshing process is adopted to obtain the required grid quality of sliding grid system as well as the mesh around the deformed blades. The simulation suggests that the deformation of reference point for flexible blade is about 6.45% of the total blade length. while the wind turbine with flexible blades delivers a power decrease by 9.56% when compared with the power delivered by rigid blades.

[1] 廖明夫, Gasch R., Schubert M., 风力发电技术，西北工業大學出版社，2009.
[2] Burton T., Sharpe D., Jenkins N. and Bossanyi E., Wind Energy Handbook, Wiley 2011.
[3] Lauha F., Steve S., Sgruti S. and Limig Q., “Global Wind Report Annual Market Update 2013,” Global Wind Energy Council, 2013.
[4] Jonkman J.M., Butterfield S., Musial W., and Scott G., “Definition of a 5-MW Reference Wind Turbine for Offshore System Development”, National Renewable Energy Labortory, NREL/TP-500-38060, 2009.
[5] Jonkman J.M., Marshall L.B., “FAST user’s guide”, Technical report NREL/EL-500-38230. National Renewable Energy Laboratory, 2005
[6] Pedersen A.S., and Steiniche C.S., “Safe Operation and Emergency Shutdown of Wind Turbines”, Aalborg Uni-versity, 2012.
[7] 李文傑，「運轉狀態下風力發電機之氣動力負荷數值研究」，台灣科技大學機械系碩士論文，2013。
[8] 郭真祥，蔡國忠，趙修武，楊淳宇，李仲凱，李岱柏，林宇，「NREL 5MW風機於台灣彰濱外海地區極限風速下之氣動力負荷數值模擬研究」，2013年台灣風能學術研討會，基隆，2013。
[9] 郭真祥，趙修武，楊淳宇，林宇，李岱柏，李仲凱，「水平軸離岸風機緊急停機過程氣動力特性分析」，第二十六屆中國造船暨輪機工程研討會暨國科會成果發表會，基隆，2014。
[10] 江俊明，「考慮流固耦合效應之水平軸風力發電機氣動力特性數值研究」，台灣科技大學機械系碩士論文，2013。
[11] Bazilevs Y., Hsu M.C., Kiendl J., Wuchner R., and Bletzinger K.U., “3D simulation of wind turbine rotors at full scale. Part II: Fluid–structure interaction modeling with composite blades”, International Journal For Numerical Methods Fluids, Vol.65, pp.236-253, 2011.
[12] Hsu M.C., Bazilevs Y. “Fluid–structure interaction modeling of wind turbines: simulating the full machine”, Comput Mech, Vol.50, pp.821-833, 2012
[13] “Fully Coupled Fluid-Structure Interaction Analysis of Wind Turbine Rotor Blades,” Abaqus Technology Brief, 2012.
[14] Tezduyar T., Aliabadi S., Behr M., Johnson A., Kalro V. and Litke M., “lowsimulation and high performance computing”, Comput Mech, Vol.18, pp.397-412, 1996.
[15] STAR-CCM+ Ver. 9.02 User`s Guide, 2014.
[16] Abaqus 6.13 User`s Manual, 2013.
[17] Demirdžić I., Perić M., “Space conservation law in finite volume calculations of fluid flow”, International Journal for Numerical Methods in Fluids, Vol 8,issue 9, pp.1037-1050, 1988
[18] Robert E., Thierry G. and Herbin R., “Finite Volume Method”, Handbooks of Numerical Analysis, Vol.7, pp.713-1020, 2006.
[19] Patankar, S.V. and Spalding, D.B., “A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows”, International Journal of Heat and Mass Transfer, Vol.15, pp.1787-1806, 1972.
[20] Wilcox, D.C., “Turbulence Modeling for CFD”, 2nd edition, DCW Industries, Inc. 1998.
[21] Menter F.R., “Two-equation eddy-viscosity turbulence modeling for engineering applications”, AIAA Journal, 1994.
[22] Bazilevs Y., Hsu M.C., Kiendl J., Wuchner R., and Bletzinger K.U., “3D simulation of wind turbine rotors at full scale. Part I: Geometry modeling and aerodynamics”, International Journal For Numerical Methods Fluids, Vol.65, pp.207-235, 2011.
[23] Behr M., Tezduyar T., “The shear-slip mesh update method”, Comput Methods Appl Mech Eng, Vol.174, pp.261-274, 1999.
[24] Behr M., Tezduyar T., “Shear-slip mesh update in 3D computation of complex flow problems with rotating mechanical components”, Comput Methods, Appl Mech Eng, Vol.190, pp.3189-3200, 2001.
[25] Donea J., Huerta A., Ponthot J.P. and Ferran R., “Arbitrary Lagrangian–Eulerian Methods”, Encyclopedia of Computational Mechanics, 2004.
[26] Ferziger, J.H. and Perić M., “Computational Methods for Fluid Dynamics”, 3rd rev. ed., Springer-Verlag, Berli, 2002
[27] Hsu M.C., Akkerman I., Bazilevs Y., “Wind turbine aerodynamics using ALE–VMS: validation and the role of weakly enforced boundary conditions”, Comput Mech, Vol.50, pp.499–511, 2012.
[28] Hughes T., Liu W., Zimmermann T., “Lagrangian–Eulerian finite element formulation for incompressible viscou flows”, Comput Methods, Vol.29, pp.329–349, 1981
[29] Lindenburg C., “Aeroelastic Modelling of the LMH64-5 Blade”, DOWEC Dutch Offshore Wind Energy Converter 1997–2003 Public Reports [CD-ROM], DOWEC 10083_001, DOWEC-02-KL-083/0, Petten, the Netherlands: Energy Research Center of the Netherlands, 2002.
[30] Kooijman H.J.T., Lindenburg, C., Winkelaar D., and van der Hooft E.L., “DOWEC 6 MW Pre-Design: Aero-elastic modeling of the DOWEC 6 MW pre-design in PHATAS”, DOWEC Dutch Offshore Wind Energy Converter 1997–2003 Public Reports [CD-ROM], DOWEC 10046_009, ECN-CX--01-135, Petten, the Netherlands: Energy Research Center of the Netherlands, 2003.
[31] Politis E.S. and Chaviaropoulos P.K., “Micrositing and classification of wind turbines in complex terrain”, Wind Energy Section Centre of Renewable Energy Sources, 2008.
[32] Richardson L.F., “The Approximate Arithmetical Solution by Finite Differences of Physical Problems Involving Differential Equations, with an Application to the Stresses in a Masonry Dam,” Philosophical Transactions of the Royal Society of London. Series A, Vol.210, pp.307-357, 1910.