本研究主要通過實驗與數值模擬方法來探討一般型與改良型薩沃紐斯風機之性能。這種垂直軸風機是由S.J. Savonius [1] 所提出，而改良型風機則由Bach [5] 所提出。本次研究之實驗使用了低阻塞比之開放式封閉測試段風洞，數值模擬方面則使用CFD軟體ANSYS FLUENT [12]來進行2維及3維之模擬。
本次研究之實驗及數值模擬結果與Kamoji [6] 等人之實驗結果作比較，得到相近的結果。改良型Bach風機在特定的TSR範圍有較好的表現，原因可透過壓力場分佈得到解釋。數值模擬之結果得以驗證。

The focus of the present study is to examine the performance of the conventional and modified Savonius turbine through experiments and numerical simulations. This type of vertical-axis wind turbine, conventional Savonius wind turbine was proposed by S.J. Savonius [1], and modified Savonius wind turbine, which was originally proposed by Bach [5]. Those experiments were conducted within open return wind tunnel with low blockage ratio; CFD software ANSYS FLUENT [12] were used to carry out both 2-D and 3-D numerical simulations.
The experimental and simulation results are compared with the experimental study presented by Kamoji et al. [6], with favorable results. The comparison showed the Bach rotor has better performance in certain TSR range, the reason is discussed accompanied by the pressure distribution. The numerical simulation results are validated.

Chapter 1 Introduction 3
1.1 Introduction 3
1.2 Literature Review 4
1.3 Motivations and Objectives 8
Chapter 2 Experimental Methods 9
2.1 Test Models 9
2.2 Power and Efficiency Calculation 10
2.3 Test Facility and Procedures 11
Chapter 3 Numerical Methods 16
3.1 Model geometry 16
3.2 Boundary Conditions 16
3.3 Computation Grid 18
3.3.1 Boundary layer calculations 18
3.4 Solution Method 22
3.5 Torque Computation for the Simulations 23
3.6 Grid Independent Test 24
Chapter 4 Results and Discussion 27
4.1 Experimental Results 27
4.2 Simulation Results 33
Chapter 5 Conclusion 38
Reference 39

Reference
[1] S.J. Savonius, “The S-rotor and its applications.”, Mechanical Engineering, Vol. 53, 1931, pp. 333-338.
[2] B.F. Blackwell, R.E. Sheldahl, L.V. Feltz, “Wind tunnel performance data for two- and three-bucket Savonius rotors.”, Sandia Laboratories, USA, Sand 76-0131 under act AT/29-11; 1978, pp. 789.
[3] N. Fujisawa, “On the torque mechanism of Savonius rotors.”, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 40, 1992, pp. 277-292.
[4] U.K. Saha, S. Thotla, D. Maity, “Optimum design configuration of Savonius rotor through wind tunnel experiments.”, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 96, 2008, pp.1359-1375.
[5] von G. Bach, “Untersuchungen ber Savonius Rotoren und verwandte Strmungsmaschinen.”, Forsch auf dem Gebiete des Ingenieurwesens, Vol. 2, 1931, pp. 218-231.
[6] M.A. Kamoji, S.B. Kedare, S.V. Prabhu, “Experimental investigations on single stage modified Savonius rotor.”, Applied Energy, Vol. 86, 2009, pp. 1064-1073.
[7] Ross I., Altman A., “Wind tunnel blockage corrections: Review and application to Savonius vertical-axis wind turbines.”, Journal of Wind Engineering and Industrial Aerodynamics, 99(5), pp. 523-538, 2011.
[8] Dobrev I., Massouh F., “CFD and PIV investigation of unsteady flow through Savonius wind turbine.”, Energy Procedia 6, 711-720, 2011.
[9] Ferrari G., Federici D., Schito P., Inzoli F. and Mereu R., “CFD study of Savonius wind turbine: 3D model validation and parametric analysis”, Renewable Energy 105, pp.722-734, 2017.
[10] Sharma, S. and Sharma, R. (2016). Performance improvement of Savonius rotor using multiple quarter blades – A CFD investigation. Energy Conversion and Management, 127, pp.43-54.
[11] Mohd ARIFF, Salim M. SALIM, Siew Cheong CHEAH (2009m December), “Wall Y+ approach for dealing with turbulent flow over a surface mounted cube: part 1 – low Reynolds number.”, Seventh International Conference on CFD in the Minerals and Process Industries, Melbourne, Australia.
[12] ANSYS FLUENT, Release 15.0, Theory Guide, ANSYS Inc.
[13] G. K. Batchelor. An Introduction to Fluid Dynamics. Cambridge Iniv.Press.Cambridge, England1967.
[14] Emmanuel, B. and Jun, W. (2011). Numerical Study of a Six-Bladed Savonius Wind Turbine. Journal of Solar Energy Engineering, 133(4), p.044503.
[15] Howell, R., Qin, N., Edwards, J. and Durrani, N. (2010). Wind tunnel and numerical study of a small vertical axis wind turbine. Renewable Energy, 35(2), pp.412-422.
[16] Roy, S. and Saha, U. (2015). Wind tunnel experiments of a newly developed two-bladed Savonius-style wind turbine. Applied Energy, 137, pp.117-125.
[17] Chen, T. and Liou, L. (2011). Blockage corrections in wind tunnel tests of small horizontal-axis wind turbines. Experimental Thermal and Fluid Science, 35(3), pp.565-569.
[18] Zhou, T. and Rempfer, D. (2013). Numerical study of detailed flow field and performance of Savonius wind turbines. Renewable Energy, 51, pp.373-381.