能源的使用使人類生活更加地進步，科技發展的進步也促使著能源的消耗增加。發展再生能源成為我們解決能源匱乏問題的方法，其中風力發電更是世界各國所關注的重點。風力發電機依據結構分為垂直軸式與水平軸式，水平軸式風機常見應用於空曠的空間其高風速時發電效率高，但在發電潛力上垂直軸式風機也不惶多讓，有著不受使用場所及來流風向的限制。相關垂直軸風機的研究中多關於其性能特性的分析比較，但了解垂直軸風機的尾流特徵對於風能開發也相當重要。
本研究利用實驗測量和CFD模擬兩種方式來探討小型垂直軸風機尾流於開放式風洞的流場特性，風機模型為一翼型為NACA9412的小型四葉垂直軸式風機。在實驗部份我們分別使用眼鏡蛇探針與熱線風速計做為實驗測量的儀器，比較量測儀器間的不同的量測特性。在CFD模擬部分，使用大渦旋模擬法求解暫態的Navier-Stokes方程式。我們使用分離求解器中的SIMPLE算法與耦合求解器中的coupled算法分別求解並比較尾流特徵。我們將分析無因次化平均時間流向速度與垂直流向速度、流向速度與垂直流向速度的紊流強度、水平剖面的動量通量，並用頻譜分析結果對此實驗所量測到的資料提供可靠度。通過比較垂直軸風機尾流的實驗測量和CFD模擬有助於了解垂直軸風機後尾流特性幫助風力能源的發展。

Energy made human life progress, and science technology advanced faces an issue which the energy consumption increased. Using the renewable energy is a method for solving the problem of energy scarcity, the wind power generation has more interest in the countries around the world. The wind turbines are according to their structures divided into vertical axis wind turbine (VAWT) and horizontal axis wind turbine (HAWT). The HAWT has commonly applied in open space and that the high efficiency at high wind speed. However, the VAWT has unlimited potential in power generation which the advantage is not a lot of restrictions on the site and the flow direction. The research relevant the VAWT is mostly about the analysis and comparison of its performance characteristics. The wake characteristics are also important for wind energy development.
In this study, comparison of experimental measurements and numerical simulations for vertical axis wind turbine wakes in an open-jet wind tunnel which the wind turbine model is an airfoil NACA9412 four-blade VAWT. The two kinds of experimental measuring instruments in the experiment which are the cobra probe and the hot wire probe for comparing the result between different measurement instruments. In the CFD simulation part, the transient Navier-Stokes equations are solved using the Large Eddy Simulation (LES). We use the SIMPLE algorithm in the split solver and the coupled algorithm in the coupled solver for solve and compare the wake characteristics. The results were analyzed normalized time-averaged velocity of streamwise and spanwise, the turbulence intensity for streamwise and spanwise, and momentum flux at the horizontal plane. The spectrum analysis with data collected using the cobra probe and the hot-wire probe shows the expected slope of -5/3 to indicate the inertial subrange, which increases the reliability of the data measured in this experiment. In order to develop the wind energy and accurate VAWT models that though the VAWT wake compaction of the measuring experiment and the CFD simulation.

[1] P. Krugman. (1999). A neglected nation gets its Nobel. Available:
http://www.slate.com/news-and-politics/2018/05/money-laundering-what-it-is-andwhat-it-looks-like-according-to-a-former-prosecutor.html
[2] 関和市 and 牛山泉, "垂直軸風車-さらなる風を求めて-基礎・設計から応用
まで," 2008 年 パワー社, 2008.
[3] I. R. E. Agency. (2018). Renewable Power Generation Costs in 2017.
[4] M. o. E. A. Bureau of Energy, R.O.C. (2018). 2017 年度全球再生能源發電成本
現況與趨勢.
[5] 陳美蘭、胡哲魁, "台灣地區風能評估與離岸風電開發潛能分析," 中華技術, p.
49, 2014.
[6] J. F. Manwell, J. G. McGowan, and A. L. Rogers, Wind energy explained: theory,
design and application. John Wiley & Sons, 2010.
[7] F. Balduzzi, A. Bianchini, E. A. Carnevale, L. Ferrari, and S. Magnani, "Feasibility
analysis of a Darrieus vertical-axis wind turbine installation in the rooftop of a
building," Applied Energy, vol. 97, pp. 921-929, 2012.
[8] S. Xie, C. L. Archer, N. Ghaisas, and C. Meneveau, "Benefits of collocating
vertical‐axis and horizontal‐axis wind turbines in large wind farms," Wind Energy,
vol. 20, no. 1, pp. 45-62, 2017.
[9] M. M. A. Bhutta, N. Hayat, A. U. Farooq, Z. Ali, S. R. Jamil, and Z. Hussain,
"Vertical axis wind turbine–A review of various configurations and design
techniques," Renewable and Sustainable Energy Reviews, vol. 16, no. 4, pp. 1926-
1939, 2012.
[10] D. MacPhee and A. Beyene, "Recent advances in rotor design of vertical axis wind
turbines," Wind Engineering, vol. 36, no. 6, pp. 647-665, 2012.
[11] H. J. Sutherland, D. E. Berg, and T. D. Ashwill, "A retrospective of VAWT
technology," Sandia Report No. SAND2012-0304, 2012.
[12] G. J. M. Darrieus, "Turbine having its rotating shaft transverse to the flow of the
current," Patent 1835018, 1931.
[13] M. Islam, D. S.-K. Ting, and A. Fartaj, "Aerodynamic models for Darrieus-type
straight-bladed vertical axis wind turbines," Renewable and Sustainable Energy
Reviews, vol. 12, no. 4, pp. 1087-1109, 2008.
[14] A. Shahzad, T. Asim, R. Mishra, and A. Paris, "Performance of a Vertical Axis
Wind Turbine under Accelerating and Decelerating Flows," Procedia CIRP, vol. 11,
pp. 311-316, 2013.
[15] M. R. Castelli, A. Englaro, and E. Benini, "The Darrieus wind turbine: Proposal for
72
a new performance prediction model based on CFD," Energy, vol. 36, no. 8, pp.
4919-4934, 2011.
[16] M. Islam, D. S. Ting, and A. Fartaj, "Desirable airfoil features for smaller-capacity
straight-bladed VAWT," Wind Engineering, vol. 31, no. 3, pp. 165-196, 2007.
[17] P. Fraunie, C. Beguier, I. Paraschivoiu, and G. Brochier, "Water channel
experiments of dynamic stall on Darrieus wind turbine blades," Journal of
Propulsion and Power, vol. 2, no. 5, pp. 445-449, 1986.
[18] J. O. Dabiri, "Potential order-of-magnitude enhancement of wind farm power
density via counter-rotating vertical-axis wind turbine arrays," Journal of
renewable and sustainable energy, vol. 3, no. 4, p. 043104, 2011.
[19] G. Tescione, D. Ragni, C. He, C. S. Ferreira, and G. Van Bussel, "Near wake flow
analysis of a vertical axis wind turbine by stereoscopic particle image velocimetry,"
Renewable Energy, vol. 70, pp. 47-61, 2014.
[20] V. Rolin and F. Porté-Agel, "Wind-tunnel study of the wake behind a vertical axis
wind turbine in a boundary layer flow using stereoscopic particle image
velocimetry," in Journal of physics: conference series, 2015, vol. 625, no. 1, p.
012012: IOP Publishing.
[21] A. Posa, C. M. Parker, M. C. Leftwich, and E. Balaras, "Wake structure of a single
vertical axis wind turbine," International Journal of Heat and Fluid Flow, vol. 61,
pp. 75-84, 2016.
[22] X. Jin, G. Zhao, K. Gao, and W. Ju, "Darrieus vertical axis wind turbine: Basic
research methods," Renewable and Sustainable Energy Reviews, vol. 42, pp. 212-
225, 2015.
[23] C. Li, S. Zhu, Y.-l. Xu, and Y. Xiao, "2.5 D large eddy simulation of vertical axis
wind turbine in consideration of high angle of attack flow," Renewable energy, vol.
51, pp. 317-330, 2013.
[24] R. Howell, N. Qin, J. Edwards, and N. Durrani, "Wind tunnel and numerical study
of a small vertical axis wind turbine," Renewable energy, vol. 35, no. 2, pp. 412-
422, 2010.
[25] S. Shamsoddin and F. Porté-Agel, "Large eddy simulation of vertical axis wind
turbine wakes," Energies, vol. 7, no. 2, pp. 890-912, 2014.
[26] S. Shamsoddin and F. Porté-Agel, "A large-eddy simulation study of vertical axis
wind turbine wakes in the atmospheric boundary layer," Energies, vol. 9, no. 5, p.
366, 2016.
[27] H. Lam and H. Peng, "Study of wake characteristics of a vertical axis wind turbine
by two-and three-dimensional computational fluid dynamics simulations,"
Renewable Energy, vol. 90, pp. 386-398, 2016.
73
[28] E. N. Jacobs, K. E. Ward, and R. M. Pinkerton, "The characteristics of 78 related
airfoil sections from tests in the variable-density wind tunnel," 1933.
[29] L. V. King, "On the convection of heat from small cylinders in a stream of fluid:
Determination of the convection constants of small platinum wires, with
applications to hot-wire anemometry," Proc. R. Soc. Lond. A, vol. 90, no. 622, pp.
563-570, 1914.
[30] D. Collis and M. Williams, "Two-dimensional convection from heated wires at low
Reynolds numbers," Journal of Fluid Mechanics, vol. 6, no. 3, pp. 357-384, 1959.
[31] H. Bruun, "Interpretation of a hot wire signal using a universal calibration law,"
Journal of Physics E: Scientific Instruments, vol. 4, no. 3, p. 225, 1971.
[32] Dantec. (2017). Probes for Hot-wire Anemometry.
[33] N. I. Corporation, "NI 9215 Datasheet."
[34] N. I. Corporation, "NI cDAQ-9174 Specifications ".
[35] Getting Started-Series 100 Cobra Probe.
[36] ACT-3X Tachometer / Totalizer / Ratemeter User Manual and Reference Guide.
[37] J. H. Ferziger and M. Peric, Computational methods for fluid dynamics. Springer
Science & Business Media, 2012.
[38] I. Fluent. (2006-09-20). ANSYS FLUENT 12.0 User's Guide - 7.4 Velocity Inlet
Boundary Conditions. Available:
https://www.sharcnet.ca/Software/Fluent6/html/ug/node222.htm
[39] I. ANSYS. (2009-01-29). ANSYS FLUENT 12.0 User's Guide - 7.3.2 Using Flow
Boundary Conditions. Available:
http://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node238.htm#keparams
[40] I. Fluent. (2006-09-20). ANSYS FLUENT 12.0 User's Guide - 7.8 Pressure Outlet
Boundary Conditions. Available:
https://www.sharcnet.ca/Software/Fluent6/html/ug/node234.htm
[41] I. ANSYS. ( 2009-01-29). ANSYS FLUENT 12.0 User's Guide -7.3.14 Wall
Boundary Conditions Available:
http://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node251.htm
[42] I. Fluent. (2006-09-20). ANSYS FLUENT 12.0 User's Guide - 7.13 Wall Boundary
Conditions. Available:
https://www.sharcnet.ca/Software/Fluent6/html/ug/node252.htm
[43] J. Boussinesq, Essai sur la théorie des eaux courantes. Impr. nationale, 1877.
[44] J. Smagorinsky, "General circulation experiments with the primitive equations: I.
The basic experiment," Monthly weather review, vol. 91, no. 3, pp. 99-164, 1963.
[45] J. W. Deardorff, "A numerical study of three-dimensional turbulent channel flow at
74
large Reynolds numbers," Journal of Fluid Mechanics, vol. 41, no. 2, pp. 453-480,
1970.
[46] S. V. Patankar and D. B. Spalding, "A calculation procedure for heat, mass and
momentum transfer in three-dimensional parabolic flows," in Numerical Prediction
of Flow, Heat Transfer, Turbulence and Combustion: Elsevier, 1983, pp. 54-73.
[47] Y.-T. Wu and F. Porté-Agel, "Atmospheric turbulence effects on wind-turbine
wakes: An LES study," energies, vol. 5, no. 12, pp. 5340-5362, 2012.