The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Christian Bak - One of the best experts on this subject based on the ideXlab platform.
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Development of the Risø wind turbine Airfoils
Wind Energy, 2004Co-Authors: Peter Fuglsang, Christian BakAbstract:This paper presents the wind turbine Airfoil development at Ris�.\nThe design method is\n\ndescribed together with our target characteristics for wind turbine\nAirfoils. The use of the\n\nCFD code Ellipsys2D for prediction of final target characteristics\nis described together with\n\nthe VELUX wind tunnel testing setup. Three Airfoil families were developed;\nRis�-A1, Ris�-P\n\nand Ris�-B1. The Ris�-A1 Airfoil family was developed for rotors of\n600 kW and larger. Wind\n\ntunnel testing and field testing showed that this Airfoil family is\nwell suited for stall and\n\nactive stall control. However, sensitivity to roughness was higher\nthan expected. Field tests\n\nof a 600 kW active stall wind turbine showed an estimated reduction\nin blade fatigue\n\nloading of up to 15% at the same annual energy yield and at the same\ntime reduced blade\n\nweight and blade solidity. The Ris�-P Airfoils were developed to replace\nthe Ris�-A1 Airfoils\n\nfor use on pitch controlled wind turbines. Improved design objectives\nshould reduce the sen-sitivity to roughness, but measurements are\nnot yet available. The Ris�-B1 Airfoil family was\n\ndeveloped for variable speed operation with pitch control of large\nmegawatt sized rotors.\n\nWind tunnel testing verified the high maximum lift for these Airfoils,\nand the Airfoils were\n\nfound to be very insensitive to leading edge roughness. Performance\nwith vortex genera-tors and Gurney flaps in combination was found\nto be attractive for the blade root part.\n\nField testing of a 1�5 MW rotor is in progress. Copyright � 2004 John\nWiley & So
Wei Li - One of the best experts on this subject based on the ideXlab platform.
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effect of relative camber on the aerodynamic performance improvement of asymmetrical blunt trailing edge modification
Journal of Engineering Thermophysics, 2017Co-Authors: Xu Zhang, G G Wang, M.j. Zhang, Wei LiAbstract:In this paper, the aerodynamic performance of the S series of wind turbine Airfoils with different relative cambers and their modifications is numerically studied to facilitate a greater understanding of the effects of relative camber on the aerodynamic performance improvement of asymmetrical blunt trailing-edge modification. The mathematical expression of the blunt trailing-edge modification profile is established using the cubic spline function, and S812, S816 and S830 Airfoils are modified to be asymmetrical blunt trailing-edge Airfoils with different thicknesses. The prediction capabilities of two turbulence models, the k-ω SST model and the S-A model, are assessed. It is observed that the k-ω SST model predicts the lift and drag coefficients of S812 Airfoil more accurately through comparison with experimental data. The best trailing-edge thickness and thickness distribution ratio are obtained by comparing the aerodynamic performance of the modifications with different trailing-edge thicknesses and distribution ratios. It is, furthermore, investigated that the aerodynamic performance of original Airfoils and their modifications with the best thickness of 2% c and distribution ratio being 0:4 so as to analyze the increments of lift and drag coefficients and lift–drag ratio. Results indicate that with the increase of relative camber, there are relatively small differences in the lift coefficient increments of Airfoils whose relative cambers are less than 1.81%, and the lift coefficient increment of Airfoil with the relative camber more than 1.81% obviously decreases for the angle of attack less than 6.3°. The drag coefficient increment of S830 Airfoil is higher than that of S816 Airfoil, and those of these two Airfoils mainly decrease with the angle of attack. The average lift–drag ratio increment of S816 Airfoil with the relative camber of 1.81% at different angles of attack ranging from 0.1° to 20.2° is the largest, closely followed by S812 Airfoil. The lift–drag ratio increment of S830 Airfoil is negative as the angle of attack exceeds 0.1°. Thus, the Airfoil with medium camber is more suited to the asymmetrical blunt trailing-edge modification.
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numerical simulation of the effect of relative thickness on aerodynamic performance improvement of asymmetrical blunt trailing edge modification
Renewable Energy, 2015Co-Authors: Xu Zhang, Wei LiAbstract:In this paper, the aerodynamic performance of wind turbine Airfoils with different relative thicknesses and their modifications has been numerically investigated to facilitate a greater understanding of the effects of maximum relative thickness and its position on the aerodynamic performance improvement of asymmetrical blunt trailing-edge modification. The lift and drag coefficients of Airfoil NACA4415 are calculated with the k-ω SST turbulence model, and are compared with experimental data to validate the simulation accuracy of the Computational Fluid Dynamics (CFD) approach. The Airfoils with different relative thicknesses are modified to be asymmetrical blunt trailing-edge Airfoils by means of the software Xfoil. The best trailing-edge thickness distribution ratio is obtained by comparing the aerodynamic performance of the modifications with different distribution ratios. The aerodynamic performance of original Airfoils and their asymmetrical modifications with the best thickness distribution ratio being 1:3 is investigated to analyze the increments of lift and drag coefficients and lift-drag ratio. Results indicate that with the increasing of relative thickness, the lift coefficient increment of NACA4418 Airfoil is the smallest for the angle of attack more than 9°, and the drag coefficient increment as a whole decreases first and then increases, but the average lift-drag ratio increment of NACA4412 Airfoil is the largest, closely followed by NACA4415 Airfoil. It is also showed that with the relative thickness position close to the leading-edge, the increments of lift and drag coefficients decrease and increase for the angle of attack more than a certain value, respectively, and the average lift-drag ratio increment of NACA4415 Airfoil is positive and larger than those of NACA4415-mod25 and NACA4415-mod20 Airfoils. Therefore, the medium thickness Airfoil whose relative thickness position is away from the leading-edge is more suited to the asymmetrical blunt trailing-edge modification.
Michael S Selig - One of the best experts on this subject based on the ideXlab platform.
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wind tunnel aerodynamic tests of six Airfoils for use on small wind turbines period of performance october 31 2002 january 31 2003
2004Co-Authors: Michael S Selig, Bryan D McgranahanAbstract:Wind Tunnel Aerodynamic Tests of Six Airfoils for Use on Small Wind Turbinesrepresents the fourth installment in a series of volumes documenting the ongoing work of th University of Illinois at Urbana-Champaign Low-Speed Airfoil Tests Program. This particular volume deals with Airfoils that are candidates for use on small wind turbines, which operate at low Reynolds numbers.
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new Airfoils for small horizontal axis wind turbines
Journal of Solar Energy Engineering-transactions of The Asme, 1998Co-Authors: Philippe Giguere, Michael S SeligAbstract:In a continuing effort to enhance the performance of small wind energy systems, one root Airfoil and three primary Airfoils were specifically designed for small horizontal axis wind turbines. These Airfoils are intended primarily for 1--5 kW variable-speed wind turbines for both conventional (tapered/twisted) or pultruded blades. The four Airfoils were wind-tunnel tested at Reynolds numbers between 100,000 and 500,000. Tests with simulated leading-edge roughness were also conducted. The results indicate that small variable-speed wind turbines should benefit from the use of the new Airfoils which provide enhanced lift-to-drag ratio performance as compared with previously existing Airfoils.
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high lift low reynolds number Airfoil design
Journal of Aircraft, 1997Co-Authors: Michael S Selig, James J GuglielmoAbstract:A new high-lift Airfoil design philosophy has been developed and experimentally validated through wind-tunnel tests. A key element of the high-lift design philosophy was to make use of a concave pressure recovery with aft loading. Three codes for Airfoil design and analysis (PROFOIL, the Eppler code, and ISES) were used to design the example S1223 high-lift Airfoil for a Reynolds number of 2 3 10 5 . In windtunnel tests, the new Airfoil yielded a maximum lift coefe cient of 2.2. With vortex generators and a 1% chord Gurney eap (used separately), the Cl,max increased to 2.3. The Airfoil demonstrates the rather dramatic gains in Cl,max over those Airfoils previously used for high-lift low Reynolds number applications.
Peter Fuglsang - One of the best experts on this subject based on the ideXlab platform.
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Development of the Risø wind turbine Airfoils
Wind Energy, 2004Co-Authors: Peter Fuglsang, Christian BakAbstract:This paper presents the wind turbine Airfoil development at Ris�.\nThe design method is\n\ndescribed together with our target characteristics for wind turbine\nAirfoils. The use of the\n\nCFD code Ellipsys2D for prediction of final target characteristics\nis described together with\n\nthe VELUX wind tunnel testing setup. Three Airfoil families were developed;\nRis�-A1, Ris�-P\n\nand Ris�-B1. The Ris�-A1 Airfoil family was developed for rotors of\n600 kW and larger. Wind\n\ntunnel testing and field testing showed that this Airfoil family is\nwell suited for stall and\n\nactive stall control. However, sensitivity to roughness was higher\nthan expected. Field tests\n\nof a 600 kW active stall wind turbine showed an estimated reduction\nin blade fatigue\n\nloading of up to 15% at the same annual energy yield and at the same\ntime reduced blade\n\nweight and blade solidity. The Ris�-P Airfoils were developed to replace\nthe Ris�-A1 Airfoils\n\nfor use on pitch controlled wind turbines. Improved design objectives\nshould reduce the sen-sitivity to roughness, but measurements are\nnot yet available. The Ris�-B1 Airfoil family was\n\ndeveloped for variable speed operation with pitch control of large\nmegawatt sized rotors.\n\nWind tunnel testing verified the high maximum lift for these Airfoils,\nand the Airfoils were\n\nfound to be very insensitive to leading edge roughness. Performance\nwith vortex genera-tors and Gurney flaps in combination was found\nto be attractive for the blade root part.\n\nField testing of a 1�5 MW rotor is in progress. Copyright � 2004 John\nWiley & So
Xu Zhang - One of the best experts on this subject based on the ideXlab platform.
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effect of relative camber on the aerodynamic performance improvement of asymmetrical blunt trailing edge modification
Journal of Engineering Thermophysics, 2017Co-Authors: Xu Zhang, G G Wang, M.j. Zhang, Wei LiAbstract:In this paper, the aerodynamic performance of the S series of wind turbine Airfoils with different relative cambers and their modifications is numerically studied to facilitate a greater understanding of the effects of relative camber on the aerodynamic performance improvement of asymmetrical blunt trailing-edge modification. The mathematical expression of the blunt trailing-edge modification profile is established using the cubic spline function, and S812, S816 and S830 Airfoils are modified to be asymmetrical blunt trailing-edge Airfoils with different thicknesses. The prediction capabilities of two turbulence models, the k-ω SST model and the S-A model, are assessed. It is observed that the k-ω SST model predicts the lift and drag coefficients of S812 Airfoil more accurately through comparison with experimental data. The best trailing-edge thickness and thickness distribution ratio are obtained by comparing the aerodynamic performance of the modifications with different trailing-edge thicknesses and distribution ratios. It is, furthermore, investigated that the aerodynamic performance of original Airfoils and their modifications with the best thickness of 2% c and distribution ratio being 0:4 so as to analyze the increments of lift and drag coefficients and lift–drag ratio. Results indicate that with the increase of relative camber, there are relatively small differences in the lift coefficient increments of Airfoils whose relative cambers are less than 1.81%, and the lift coefficient increment of Airfoil with the relative camber more than 1.81% obviously decreases for the angle of attack less than 6.3°. The drag coefficient increment of S830 Airfoil is higher than that of S816 Airfoil, and those of these two Airfoils mainly decrease with the angle of attack. The average lift–drag ratio increment of S816 Airfoil with the relative camber of 1.81% at different angles of attack ranging from 0.1° to 20.2° is the largest, closely followed by S812 Airfoil. The lift–drag ratio increment of S830 Airfoil is negative as the angle of attack exceeds 0.1°. Thus, the Airfoil with medium camber is more suited to the asymmetrical blunt trailing-edge modification.
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numerical simulation of the effect of relative thickness on aerodynamic performance improvement of asymmetrical blunt trailing edge modification
Renewable Energy, 2015Co-Authors: Xu Zhang, Wei LiAbstract:In this paper, the aerodynamic performance of wind turbine Airfoils with different relative thicknesses and their modifications has been numerically investigated to facilitate a greater understanding of the effects of maximum relative thickness and its position on the aerodynamic performance improvement of asymmetrical blunt trailing-edge modification. The lift and drag coefficients of Airfoil NACA4415 are calculated with the k-ω SST turbulence model, and are compared with experimental data to validate the simulation accuracy of the Computational Fluid Dynamics (CFD) approach. The Airfoils with different relative thicknesses are modified to be asymmetrical blunt trailing-edge Airfoils by means of the software Xfoil. The best trailing-edge thickness distribution ratio is obtained by comparing the aerodynamic performance of the modifications with different distribution ratios. The aerodynamic performance of original Airfoils and their asymmetrical modifications with the best thickness distribution ratio being 1:3 is investigated to analyze the increments of lift and drag coefficients and lift-drag ratio. Results indicate that with the increasing of relative thickness, the lift coefficient increment of NACA4418 Airfoil is the smallest for the angle of attack more than 9°, and the drag coefficient increment as a whole decreases first and then increases, but the average lift-drag ratio increment of NACA4412 Airfoil is the largest, closely followed by NACA4415 Airfoil. It is also showed that with the relative thickness position close to the leading-edge, the increments of lift and drag coefficients decrease and increase for the angle of attack more than a certain value, respectively, and the average lift-drag ratio increment of NACA4415 Airfoil is positive and larger than those of NACA4415-mod25 and NACA4415-mod20 Airfoils. Therefore, the medium thickness Airfoil whose relative thickness position is away from the leading-edge is more suited to the asymmetrical blunt trailing-edge modification.