【作者】 李伟；

【导师】 熊克；

【作者基本信息】 南京航空航天大学 ， 工程力学， 2012， 博士

【摘要】 减阻是飞机设计的主要任务之一，翼梢小翼能有效降低飞机的诱导阻力。传统翼梢小翼仅面向巡航状态优化，而在起飞、爬升等非设计状态的减阻效率较低。针对该问题，本文研究了一种可变高度和倾斜角的变体翼梢小翼，能根据飞机的飞行状态主动改变自身的高度和倾斜角，实现整个飞行包线内实时优化飞机阻力特性的目的。本文的研究工作重点围绕以下三方面进行：首先，研究了变体翼梢小翼的变形方式和变形范围问题。翼梢小翼的参数类型较多，各参数对小翼减阻效率的影响程度也不同，变体翼梢小翼应改变哪些参数、以及这些参数在什么范围内变化，是研究变体翼梢小翼面临的首要问题。针对变形方式问题，本文采用Plackett-Burman试验设计分析了小翼的各类几何参数对减阻效率的影响程度，筛选出对小翼减阻效率影响最大的关键参数，以此为依据指出了变体翼梢小翼的变形方式。在此基础上，采用响应曲面设计得到了小翼的关键参数在起飞、爬升和巡航阶段的最佳值，确定了小翼关键参数的变形范围。研究结果表明，翼梢小翼的高度和倾斜角是影响其减阻效率的关键参数，因此变体翼梢小翼应该通过改变高度和倾斜角的方式来提高起飞、爬升阶段的减阻效率。其次，研究了变体翼梢小翼的驱动技术。以变体翼梢小翼的变形方式和变形范围为依据，本文提出了三种驱动机构——用于变高度翼梢小翼的伸缩栅格、用于变倾角翼梢小翼的主动弯曲梁、以及用于高度和倾斜角复合式变形的差动式伸缩栅格。通过数值模拟和模型实验研究了三种驱动机构的运动特性，推导了机构的运动方程，并研究了相应的控制方法。研究结果显示，三种驱动机构可以实现变体翼梢小翼所需的变形动作。第三，研究了变体翼梢小翼的气动收益问题。本文采用计算流体力学（CFD）与风洞实验相结合的方法，分析了变体翼梢小翼变形前与变形后对机翼展向载荷分布、翼梢尾涡流场控制、机翼的升阻力和翼根弯矩的影响。研究结果表明，变体翼梢小翼不仅能显著改善飞机起飞阶段的气动效率，还能进一步削弱翼尖尾涡强度。其中，变高度的变形方式获得的气动收益最大，高度和倾斜角复合式变形获得的气动收益次之，而变倾斜角的变形方式获得的气动收益最小。但是，三种变形方式都会引起气动载荷向机翼翼尖区集中，带来额外的翼根弯矩增量，因此必须保证变形幅度不得超过预设的变形范围，否则会损害机翼结构的安全。本文研究工作在机械结构力学及控制国家重点实验室完成，并得到了国家自然科学基金项目“用于近空间飞行器仿生机翼的驱动器基础研究”（项目批准号：90605003）的资助。更多还原

【Abstract】 Drag reduction is one of the main goals in aircraft design. Although winglet has the capability ofreducing the induced drag of an aircraft, traditional designs of the winglet are only optimized forcruise phase and are inefficient at non-cruise condition, including taking off phase and climbing phase.In this thesis, a new morphing winglet design is proposed in which the height and cant angle of thewinglet can be changed to provide the optimal drag reduction efficiency for both cruise andnon-cruise conditions, overcoming the shortage of traditional winglet at non-cruise condition.The main contents and achievements are as follows.First the deformation modes and the range the parameters of the morphing winglet areinvestigated. Many parameters are employed to describe the performances of the winglet, each ofwhich has different influence on drag reduction efficiency. The main challenges of morphing wingletsare to determine which parameter should be deformed and what is the deformation range. By usingPlackett-Burman test method, the effects of the winglet parameters on drag reduction are analyzed todetermine the key parameters that affected the drag reduction, from which the deformation mode ofwinglets could be obtained. The optimal value of the key parameters and their ranges during takingoff, climbing and cruise are then obtained by using the response curve surface design. The resultsshowed that the key parameters of winglet are height and cant angle, which suggests that themorphing winglet should change its height and cant angle to improve the drag reduction efficiencyduring taking off and climbing.Second actuation techniques of the morphing winglet are studied. Three types of drivingmechanisms are investigated which include the retractable grid for variable height winglet, the activebending beams for variable cant angle winglet and the antagonistic retractable grid for variable heightand cant angle winglet. The kinematics of the three mechanisms was studied by numerical simulationand model experiments to derive the equations of motion and find the control method. The resultsshow that the three kinds of driving mechanisms could meet the requirements of the morphingwinglets.Finally, the aerodynamic benefit of morphing winglet is analyzed. By combining computationalfluid dynamics (CFD) with wind tunnel test, the aerodynamic benefit of morphing winglet isconsidered. The spanwise pressure distribution, the wingtip vortices dissipation, the aerodynamiccharacteristics and root bending moment of a wing before and after morphing were analyzed. Theresult demonstrates that the morphing winglet could significantly improve the aerodynamic performance of an aircraft in the takeoff phase of flight, among which the height deformation mode isthe most efficient in improving the aerodynamic benefit of morphing winglet, the height and cantangle coupled deformation mode is lesser and the cant angle deformation mode is the least.Furthermore, all three ways of deformation modes would induce the pressure augmentation inoutboard wing, which produce extra wing root bending moment. Therefore, the morphing wingletshould be controlled within the optimal range to prevent from wing structure failure.This thesis is accomplished in State Key Laboratory of Mechanics and Control of MechanicalStructures, as well as funded by the National Natural Science Foundation of China under Contract No.90605003.更多还原