【作者】 刘玉荣；

【导师】 丛茜；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2012， 硕士

【摘要】 鸟类经过亿万年进化具有优良的飞行特性，翅膀宽大的鸟类由于其翅膀与空气接触面积大，在飞行时可提供较大升力；翅膀狭长的鸟类，由于翅膀展向较大且成梭形，使其飞行过程中具有较小的阻力，可实现长距离的滑行，飞行效率极高。鸟类优良的飞行特性由其翅膀羽毛结构及翼型形态决定，其中翼型是决定其飞行效率高低的关键因素，鸟类翼型的研究对于风力发电机叶片、飞机机翼等靠流体工作的关键部件具有重要的仿生学意义和应用前景。本文以家燕为研究对象，对家燕的羽毛特性进行了分析，获取了家燕羽毛结构与飞行特性之间的关系。家燕羽毛的羽轴和羽片组成结实而有弹性的羽片，可以减小空气阻力，增加鸟体浮力；羽毛具有较强的疏水性及各向异性，有利于水滴滚落，去除鸟体污物，降低飞行阻力，实现快速飞行。通过对家燕运动学分析获得了家燕滑翔时常见的两种翅翼形态：后掠形翅翼和完全展开形翅翼。利用逆向工程技术截取了两种翅翼展弦比为25%、30%、35%、40%、45%、50%的翼型，并获取了翼型的几何参数。利用ICEM软件对所提取的翼型进行网格划分，用FLUENT软件对其在雷诺数为6×10~4、8×10~4，攻角为0~15°的条件下进行了气动特性的数值模拟仿真分析，结果表明：家燕完全展开形翅翼展弦比为25%的翼型和家燕后掠形翅翼展弦比为35%的翼型具有最优的气动特性，雷诺数Re=6×10~4时，家燕完全展开形翅翼展弦比为25%的翼型升力系数比标准翼型提高1.4倍，升阻比比标准翼型提高了30%，家燕后掠形翅翼展弦比为35%的翼型的升力系数比标准翼型提高了1.2倍，升阻比比标准翼型提高了48%；当Re=8×10~4时，家燕完全展开形翅翼展弦比为25%的翼型升力系数比标准翼型提高了1.4倍，升阻比比标准翼型提高了22.5%，家燕后掠形翅翼展弦比为35%的翼型的升力系数比标准翼型提高了1.03倍，升阻比比标准翼型提高了48%。对生物翼型提高气动性能的机理进行分析发现：（1）翼型具有较小的厚度与前缘半径，使得翼型迎风面积小，阻力小；（2）翼型的静压曲线所形成面积较大，翼型具有较大的升力；（3）翼型的最大厚度靠近后缘，能够推迟失速现象的发生，使其能量损失小，效率高。采用雕刻机对具有代表性的家燕翼型和标准翼型进行加工，利用小型风洞实验台对翼型进行了气动特性测试实验，实验结果表明在不同的风速下家燕完全展开形翅翼展弦比为25%的翼型和家燕后掠形翅翼展弦比为35%的翼型的气动特性最优，在不同的风速下也具有良好的适应性，验证了数值模拟实验的正确性。这两种优良翼型的获取为以后翼型的提取提供了一种有效的方法，具有指导性意义。更多还原

【Abstract】 After million years of evolution, birds have excellent flight characteristics: birds withlarge wings can produce higher lift because of the large contact area between their wings andthe air, while the birds with long, narrow wings can carry out long-distance gliding becausethe large spanwise and shuttle-shape wings can reduce the air resistance to improve theflying efficiency. The excellent flight characteristics are decided by the feather structure andairfoil shape of the wings, especially the airfoil which is a key factor closely related to flightinefficiency. The research on bird airfoil has its important bionic meaning and applicationprospects, which provides a design inspiration for wind turbine blades, wings and other keycomponents in the aircraft.This thesis takes the barn swallows as an example, analysis the feather characteristic,and concludes the relationships between the feather structure and the flight characteristics. Inbarn swallows, feathers, rachis and pinna constitute a strong and flexible pinna, which canreduce the air resistance and increase the buoyancy of the bird’s body. On the other hand, thefeathers are hydrophobic and anisotropic, keeping the body clean from water and dirt. Thisproperty efficiently reduces the wind resistance and allows the bird to achieve rapid flight.This thesis presents a thorough kinematics analysis of the barn swallows, concludes twokinds of wing patterns when they are gliding: swept-shaped wings and fully expandedshaped wings. By using reverse engineering technology, interception of two wings patterns isperformed on airfoil in aspect ratio25%,30%,35%,40%,45%,50%, and gained the wingsection geometry parameter.Airfoil meshing is extracted using ICEM software, Numerical simulation on theaerodynamic characteristic using FLUENT software under the condition of using Reynoldsnumber of6×10~4、8×10~4, and attack angle of0~15°, results show that the airfoil at thefully expanded shaped wings aspect ratio of25%and swept-shaped wings aspect ratio of35%of the airfoil have the best aerodynamic characteristics. When the Reynolds numberreaches Re=6×10~4, Barn swallows fully expanded airfoil aspect ratio of25%is1.4times than the standard airfoil, Lift-drag ratio increased30%, Barn swallows Swept-shaped wingsaspect ratio of35%lift coefficient is1.2times and Lift-drag ratio increased48%than thestandard airfoil; When the Reynolds number reaches Re=8×10~4, Barn swallows fullyexpanded airfoil aspect ratio of25%is1.4times than the standard airfoil, Lift-drag ratioincreased30%, Barn swallows Swept-shaped wings aspect ratio of35%lift coefficient is1.03times and Lift-drag ratio increased48%than the standard airfoil; Analysis of Biologicalairfoil to improve the the mechanism of the aerodynamic performance showed that:(1) Thewing section has the small thickness and the leading edge radius, causes the wing sectionfrontal area to be small, the resistance is small;(2) The wing section static pressure curveforms the area to be big, the wing section has the big lifting force;(3) The maximumthickness of the airfoil near the trailing edge, which be able to delay the occurrence of stall,and ensure small energy loss, high efficiency.The representative and standard airfoil of the swallow airfoil are processed on theengraving machine, and their aerodynamic characteristics are tested in the small wind tunnel.Results show that the barn swallows in different wind speeds, fully expanded-shaped wingsin aspect ratio of25%and barn swallows swept-shaped wings in aspect ratio for35%of theairfoil provide the optimal aerodynamic characteristics. They pertain good adaptability underdifferent wind speed, which verified the correctness of the numerical simulation result. Theacquisition of these two excellent airfoils provides significant guidance for the future airfoilextraction.更多还原