基于翼型凹变的叶片结构动力学性能优化方法研究
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摘要
针对某分布式水平轴风力机叶片,首次提出于翼型吸力面上进行翼型凹变的结构改良,以额定工况时不降低叶片功率输出为前提,成功地将翼型凹变应用于叶片刚度、阻尼比和固有频率的有益改进。研究揭示,翼型向内侧凹变可较好地控制叶片吸力面上气流交汇的位置和影响范围,配合凹槽对汇聚流线的诱导效应,可在一定程度上减小气体流动的能量损失,进而提升叶片的气动性能。此外,翼型凹变可显著提升风轮1阶、2阶阻尼比3%～9%,提升叶片刚度值32%,同时可有效降低叶片最大位移和最大应变值分别为28%和19%。翼型凹变在风力机叶片设计中的成功应用,不仅可为翼型族的衍生提供了新的实现方法,同时可为叶片气动性能和结构动力学性能的兼优性开发提供新的实现途径。
In this study, the blade of a distributed horizontal axis wind turbine was selected as the research model and its stiffness, damping ratio and natural frequency were improved for the first time by airfoil concave on the premise of not reducing the blade power output under the rated working condition. The research revealed that the airfoil's inner concave on the suction surface could better control the position and influence range of airflow convergence on suction surface, and combined with the inducing effect of grooves on the convergence streamline, it can reduce the energy loss of airflow to a certain extent and improve the blade's aerodynamic performance. In addition, the airfoil concave can significantly increase 1 st-order and 2 nd-order damping ratios of the wind wheel by 3%— 9%, increase the stiffness value of the blade by 32%, and effectively reduce the maximum displacement and the maximum strain of the blade by 28% and 19%, respectively. Successful application of airfoil concave in the design of wind turbine blades will not only provide a new method for the derivation of airfoil family, but can also provide a new way for synchronous optimization of the aerodynamic performance and structural dynamic performance of the blade.
In this study, the blade of a distributed horizontal axis wind turbine was selected as the research model and its stiffness, damping ratio and natural frequency were improved for the first time by airfoil concave on the premise of not reducing the blade power output under the rated working condition. The research revealed that the airfoil's inner concave on the suction surface could better control the position and influence range of airflow convergence on suction surface, and combined with the inducing effect of grooves on the convergence streamline, it can reduce the energy loss of airflow to a certain extent and improve the blade's aerodynamic performance. In addition, the airfoil concave can significantly increase 1 st-order and 2 nd-order damping ratios of the wind wheel by 3%— 9%, increase the stiffness value of the blade by 32%, and effectively reduce the maximum displacement and the maximum strain of the blade by 28% and 19%, respectively. Successful application of airfoil concave in the design of wind turbine blades will not only provide a new method for the derivation of airfoil family, but can also provide a new way for synchronous optimization of the aerodynamic performance and structural dynamic performance of the blade.
引文
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[2]MOHAMED M H.Performance investigation of H-rotor darrieus turbine with new airfoil shapes[J].Energy,2012,47(1):522-530.
[3]WANG,Q,WANG,J,SUN,J F,et al.Optimal design of wind turbine airfoils based on functional integral and curvature smooth continuous theory[J].Aerospace Science and Technology,2016,55:34-42.
[4]CHEN J,WANG Q,ZHANG S Q,et al.A new direct design method of wind turbine airfoils and wind tunnel experiment[J].Applied Mathematical Modelling,2016,40(3):2002-2014.
[5]LIU Y X,YANG C,SONG X C.An airfoil parameterization method for the representation and optimization of wind turbine special airfoil[J].Journal of Thermal Science,2015,24(2):99-108.
[6]MEI Y,QU J J,LI Y.Airfoil design for vertical axis wind turbine operating at variable tip speed ratios[J].Open Mechanical Engineering Journal,2015,9(1):1007-1016.
[7]BEDON G,DE BETTA S,BENINI E.Performance-optimized airfoil for darrieus wind turbines[J].Renewable Energy,2016,94:328-340.
[8]TARTUFERI M,D’ALESSANDRO V,MONTELPARE S,et al.Enhancement of savonius wind rotor aerodynamic performance:a computational study of new blade shapes and curtain systems[J].Energy,2015,79:371-384.
[9]BIRAJDAR M,KALE S,SAPALI S N.Effects of design parameters on aerodynamic performance of new profile small wind turbine blades[C]∥ASME 2015 International Mechanical Engineering Congress and Exposition.Houston:IMECE,2016.
[10]MENON M,PONTA F,SUN X,et al.Aerodynamic analysis of flow-control devices for wind turbine applications based on the trailing-edge slotted-flap concept[J].Journal of Aerospace Engineering,2016,29(5):04016037.
[11]CAI C,ZUO Z,MAEDA T,et al.Periodic and aperiodic flow patterns around an airfoil with leading-edge protuberances[J].Physics of Fluids,2017,29(11)115110.
[12]LIU P,CHEN J,XIN S,et al.Experimental investigation on the tip vortex of a wind turbine with and without a slotted tip[C]∥ASME Turbo Expo 2017:Turbomachinery Technical Conference and Exposition.North Carolind:ASME,2017.
[13]AHMED M R,NABOLANIWAQA E.Performance improvement of a wind turbine blade designed for low wind speeds with a passive trailing edge flap[C]∥ASME 2012 International Mechanical Engineering Congress and Exposition.Houston:ASME,2012.
[14]WANG G F,ZHANG M M,XU J Z.Experimental study on bionic wavy edge aerodynamic characteristics of airfoil[J].Journal of Engineering Thermophysics,2013,34(10):1842-1846.
[15]HANSEN K L,KELSO R M,DALLY B B.Performance variations of leading-edge tubercles for distinct airfoil profiles[J].Aiaa Journal,2011,49(1):185-194.
[16]SUN X,DAI Q,MENON M,et al.Design and simulation of active external trailing-edge flaps for wind turbine blades on load reduction[J].Journal of Aerospace Engineering,2017,30(5):04017062.