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Effect of Blade Thickness, Solidities and Pitch Angle on the VAWT System
|關鍵字:||VAWT;垂直軸風機;Double Multiple Streamtube model;solidity;pitch angle;多管流理論模型;疏密比;傾角||出版社:||機械工程學系所||引用:||Thumthae, C. and Chitsomboon, T., "Optimal Angle of Attack for Untwisted Blade Wind Turbine." Renewable energy, Vol. 34, pp. 1279 -1284, 2009. Takao, M., Takita, H., "Experimental Study of Straight-Bladed Vertical Axis Wind Turbine With a Directed Guide Vane Row," Proceedings of the 28th International Conference on Ocean, Offshore, and Arctic Engineering, pp.1-9, 2009. Ferreira, C., G. van Kuik.,"Visualization by PIV of Dynamic Stall on a Vertical Axis Wind Turbine," Experiments in Fluids, Vol. 64, pp. 97-108, 2009. Saeed, F. and Paraschivoiu, I., "Inverse Airfoil Design Method for Low-Speed Straight-Bladed Darrieus-Type VAWT Applications," in 7th world wind energy conference, June 24th-26th, 2008. Ponta, F. L. and Jacovkis, P. M., "A Vortex Model for Darrieus Turbine Using Finite Element Techniques," Renewable energy, Vol. 24, pp 1-18, 2001. Li, Y., and Tagawa, K., "Performance Effects of Attachment on Blade on a Straight-bladed Vertical Axis Wind Turbine," Current Applied Physics, S335-S338, Vol.10, 2010 Fujisawa, N. and Shibuya, S., "Observations of Dynamic Stall on Darrieus Wind Turbine Blades,"Journal of Wind Engineering and Industrial Aerodynamics, Vol. 89, pp. 201-214, 2001. Fiedler, A. J. and Tullis, S., "Blade Offset and Pitch Effects on a High Solidity Vertical Axis Wind Turbine," Wind Engineering Vol.33, pp. 237-246, 2009. Brahimp, M., and Allet, A.,"Aerodynamic Analysis Models for Vertical-Axis Wind Turbines," International Journal of Rotaing Machinery, Vol. 2, pp.15-21, 1995. Lanzafame, R., and Messina, M.,"Fluid Dynamics Wind Turbine Design: Critical Analysis,Optimization and Application of BEM theory,"Renewable Energy," Vol. 32, pp.2291-2305, 2007. Buhl Jr, L., "A New Empirical Relationship Between Thrust Coefficient and Induction Factor for the Turbulent Windmill State,"Technical report NREL/TP-500-36834, August, 2005. Sheldahl, R.E. and Klimes, P.C., "Aerodynamic Characteristics of Seven Symmetrical Airfoil Sections Through 180-Degree Angle of Attack for Use in Aerodynamic Analysis of Vertical Axis Wind turbine, " SAND80-22114,Vol. 2, pp.15-21, 1981. Iida, A., Kato, K., and Mizuno, A., "Numerical Simulation of Unsteady Flow and Aerodynamic Performance of Vertical Axis Wind Turbine With LES," 16th Australasion Fluid Mechanics Conference, pp. 1295-1298, 2007. South, P., and Rangi, R.S., "A Wind Tunnel Investigation of a 14ft Diameter Vertical Axis Windmill, Low Speed Aerodynamics Laboratory(Canada) Laboratory Technical Report, " National Aeronautical Establishment, LTR-LA-105, 1972. Klimas, P., and Worstell, M.,"Effects of Blade Preset Pitch/Offset on Curved-BladeDarrieus Vertical Axis Wind Turbine Performance," Sandia-81-1762, Albuerque, NM, 1981. Migliore, P.,"Comparison of NACA 6-series and 4-digit Airfoils for Darrieus Wind Turbines,"Journal of Energy, Vol.7, p.291, 1983 Kirke, B.,"Evaluation of Self-Starting Vertiocal Axis Wind Turbinges For Stand-alone Wind Turbines For Stand-Alone Applcations,"April, 1998 Glauert , H., "The Analsis of Experimental Results in the Windmill Brake and Vortex Ring States of an Airscrew," Reports and Momoranda, No.1026, February. 1926 Paraschivoiu, I., and Delclaux, F., "Double multiple streamtube model with recent improvements," Journal of Energy, Vol.7, p.250-255, 1983 莊昌儒(2010).具有疏密比之垂直風機性能分析.國立中興大 學機械工程系碩士論文||摘要:||
This study analyzes the effects of the blade thickness, the solidity and the pitch angle on the performance of VAWT system by Double Multiple Streamtube model (DMS model). The VAWT system includes three blades, situated 120°apart, with a chord length 0.1009m. The inflow wind speed is 10m/s, and the uncambered blades ( NACA0012, NACA0015 and NACA0018) are employed. The solidity varies from 0.07 to 0.3 by changing the rotating radius. The pitch angles of the blade are 0°and -2°. Some important results are concluded as follows:
(1)When the tip speed ratio (TSR) is smaller than 3, the relative angle of attack are greater than the static stall angle during most of the rotating cycle. Thus, the cyclic tangential forces are mostly negative at the upwind and the downwind regions during each revolution, and result in a negative average torque. When the TSR is greater than 3, the relative angle of attack are smaller than the static stall angle, thus, the cyclic tangential forces are positive and increases in magnitude at the upwind region. On the other hand, those in the downwind region are negative and small in magnitude. This leads to a positive averaged torque during each revolution. (2)When the thickness of the uncambered airfoil increases, the critical tip speed ratio that produces the positive power and torque coefficients decreases. While the thickness decreases, both the maximum power and torque coefficients and the corresponding tip speed ratio increase. (3) The effect of solidity on the critical TSR that generates the positive torque and power coefficients is insignificant. As the solidity decreases, the changes of the magnitudes of maximum power and torque coefficients are minor; however, the corresponding TSR increases. (4)When the pitch angle is fixed at 0°, the operating ability at low TSR is better than that for the pitch angle of -2°. The maximum power and torque coefficients for the zero pitch angle are always greater than those for the pith angle of -2°.
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