Aerodynamic Interactions Between Contralateral Wings and Between Wings and Body of a Model Insect at Hovering and Small Speed Motions

In this paper, we study the aerodynamic interactions between the contralateral wings and between the body and wings of a model insect, when the insect is hovering and has various translational and rotational motions, using the method numerically solving the Navier-Stokes equations over moving overset grids. The aerodynamic interactional effects are identified by compar-ing the results of a complete model insect, the corresponding wing pair, single wing and body without the wings. Horizontal, vertical and lateral translations and roll, pitch and yaw rotations at small speeds are considered. The results indicate that for the motions considered, both the interaction between the contralateral wings and the interaction between the body and wings are weak. The changes in the forces and moments of a wing due to the contralateral wing interaction, of the wings due to the pres-ence of the body, and of the body due to the presence of the wings are generally less than 4.5%. Results show that aerodynamic forces of wings and body can be measured or computed separately in the analysis of flight stability and control of hovering in-sects.     

小展弦比飞翼布局作战飞机偏航轴飞行品质评定

依据MIL—STD—1797A飞行品质规范,对小展弦比飞翼布局作战飞机的偏航轴飞行品质进行了评定研究。评定结果表明：由于构型的原因,飞翼布局飞机本体的稳定特性和阻尼特性都较差,因此飞行控制系统对其动态响应特性的调节作用更加明显。稳态配平特性主要受构型的影响,飞翼布局飞机一般不能完全满足飞行品质的要求。由于可控性的设计要求需采用多操纵面的组合操纵,控制分配技术导致某些现有的品质准则需要修改。小展弦比飞翼布局飞机取消了垂尾（方向舵）并采用了新型操纵面（ICE）,在某些情形下对偏航轴操纵效能的需求与常规飞机相比存在较大的差异。总之,在飞翼布局作战飞机的构型设计、飞控系统设计以及飞行品质评定条款的制定、实施中,均需考虑这些新的飞行品质特性。     

Nonlinear dynamics of a flapping rotary wing: Modeling and optimal wing kinematic analysis

The analysis of the passive rotation feature of a micro Flapping Rotary Wing(FRW)applicable for Micro Air Vehicle(MAV) design is presented in this paper. The dynamics of the wing and its influence on aerodynamic performance of FRW is studied at low Reynolds number(~10~3).The FRW is modeled as a simplified system of three rigid bodies: a rotary base with two flapping wings. The multibody dynamic theory is employed to derive the motion equations for FRW. A quasi-steady aerodynamic model is utilized for the calculation of the aerodynamic forces and moments. The dynamic motion process and the effects of the kinematics of wings on the dynamic rotational equilibrium of FWR and the aerodynamic performances are studied. The results show that the passive rotation motion of the wings is a continuous dynamic process which converges into an equilibrium rotary velocity due to the interaction between aerodynamic thrust, drag force and wing inertia. This causes a unique dynamic time-lag phenomena of lift generation for FRW, unlike the normal flapping wing flight vehicle driven by its own motor to actively rotate its wings. The analysis also shows that in order to acquire a high positive lift generation with high power efficiency and small dynamic time-lag, a relative high mid-up stroke angle within 7–15° and low mid-down stroke angle within -40° to -35° are necessary. The results provide a quantified guidance for design option of FRW together with the optimal kinematics of motion according to flight performance requirement.     

A review of bird-like flapping wing with high aspect ratio

Bird-like flapping-wing vehicles with a high aspect ratio have the potential to fulfill missions given to micro air vehicles, such as high-altitude reconnaissance, surveillance, rescue, and bird group guidance, due to their good loading and long endurance capacities. Biologists and aeronautical researchers have explored the mystery of avian flight and made efforts to reproduce flapping flight in bioinspired aircraft for decades. However, the cognitive depth from theory to practice is still very limited. The mechanism of generating sufficient lift and thrust during avian flight is still not fully understood. Moving wings with unique biological structures such as feathers make modeling, simulation, experimentation, and analysis much more difficult. This paper reviews the research progress on bird-like flapping wings from flight mechanisms to modeling. Commonly used numerical computing methods are briefly compared. The aeroelastic problems are also highlighted. The results of the investigation show that a leading-edge vortex can be found during avian flight. Its induction and maintenance may have a close relationship with wing configuration, kinematics and deformation. The present models of flapping wings are mainly two-dimensional airfoils or three-dimensional single root-jointed geometric plates, which still exhibit large differences from real bird wings. Aeroelasticity is encouraged to consider the nonignorable effect on aerodynamic performance due to large-scale nonlinear deformation. Introducing appropriate flexibility can improve the peak values and efficiencies of lift and thrust, but the detailed conclusions always have strong background dependence.     

飞翼布局无人机变形机翼设计与模型验证研究

对飞翼布局无人机变形机翼和变形机翼传动机构进行了设计,根据设计结果制作验证模型进行风洞实验和外场飞行试验,以此研究伸缩段机翼对飞行器机翼整体气动性能的影响。结果表明:采用变形机翼技术,可以通过实时控制机翼的气动外形保持较高的气动效率,提高飞机在巡航状态下的升力和高速飞行状态下的机动性,满足飞机在各种任务剖面的战术性能要求。     

中等后掠机翼平面参数设计与实验研究

采用Euler数值计算方法,对60多种中等后掠角及展弦比的切尖菱形机翼、双三角机翼纵向气动力特性进行了计算、分析和比较,从中筛选出16种切尖菱形机翼、14种双三角机翼进行了全机高速风洞实验研究,给出了机翼的展弦比、前缘后掠角、根梢比(后缘前掠角)及几何扭转变化对全机升力、阻力及俯仰力矩的影响曲线和数据分析,在此基础上提出了用于定量估算两类机翼纵向气动力特性的关系式及修正因子。本文研究结果为建立战斗机机翼气动力设计数据库及飞机气动布局设计提供了实用的数据和设计参考。     

Experimental investigation of influence of strake wings on self-induced roll motion at high angles of attack

The modern high performance air vehicles are required to have extreme maneuverability,which includes the ability of controlled maneuvers at high angle of attack. However, the nonlinear and unsteady aerodynamic phenomena, such as flow separation, vortices interaction, and vortices breaking down, will occur during the flight at high angle of attack, which could induce the uncommanded motions for the air vehicles. For the high maneuverable and agile air missile, the nonlinear roll motions would occur at the high angle of attack. The present work is focused on the selfinduced nonlinear roll motion for a missile configuration and discusses the influence of the strake wings on the roll motion according to the results from free-to-roll test and PIV measurement using the models assembled with different strake wings at a = 60°. The free-to-roll results show that the model with whole strake wings(baseline), the model assembled with three strake wings(Case A)and the model assembled with two opposite strake wings(Case C) experience the spinning, while the model assembled with two adjacent strake wings(Case B), the model assembled with one strake wing(Case D) and the model with no strake wing(Case E) trim or slightly vibrate at a certain "×"rolling angle, which mean that the rolling stability can be improved by dismantling certain strake wings. The flow field results from PIV measurement show that the leeward asymmetric vortices are induced by the windward strake wings. The vortices would interact the strake wings and induce crossflow on the downstream fins to degrade the rolling stability of the model. This could be the main reason for the self-induced roll motion of the model at a = 60°.     

三维仿生悬停扑翼的时间非对称扑动气动特性

基于对现有黄蜂飞行观察实验的分析,建立了不同下扑和上挥时间非对称扑动悬停扑翼运动轨迹模型,并采用数值求解三维层流Navier-Stokes(N-S)方程的方法,研究了采用不同下扑和上挥时间比的仿生悬停扑翼气动特性.结果表明采用适当的时间非对称扑动可以增强悬停扑翼的气动性能.进一步通过对不同时间非对称扑动扑翼流场分析得出,采用时间非对称扑动不但可以增强使扑翼产生高升力的旋转环流机制,而且还可以增强扑翼表面涡流和展向流的强度,从而使扑翼具有更好的气动性能.      

微型扑翼飞行器扑翼/尾翼气动干扰的数值研究

以二维刚性约束条件下的微型扑翼飞行器模型为研究对象,在动网格技术基础上,应用非定常数值分析手段对比分析了单翼/纵列翼布局的气动性能,深入研究了纵列翼缩减频率、扑翼—尾翼无量纲水平间距、来流攻角对其气动性能的影响.结果表明:①纵列翼尾翼对扑翼产生正效应干扰,相对于单翼布局,扑翼—尾翼无量纲水平间距为0.5倍翼型弦长时的纵列翼布局的推力系数和推进效率分别增加28.7%和5.7%;②缩减频率是影响推力的关键参数,随着缩减频率的增加,脱落涡的强度增加,推力系数增大.对于单翼、纵列翼两种布局模式,当缩减频率在1.0附近时推进效率达到最优;③对于纵列翼布局,在扑翼—尾翼无量纲水平间距为1.1倍翼型弦长时推进效率达到峰值;④在0°~20°来流攻角变化范围内,随着来流攻角的增加,升力系数增加,推力系数减小,当来流攻角大于9°时,两种布局的推力均为负值.      

翼尖连接机翼布局弹性气动力探讨

翼尖连接机翼(Joined Wing)布局将后掠的前翼和前掠的后翼在翼尖处用端板相连,后掠翼和前掠翼互相依存,克服平直机翼的局限,提高飞行临界M数,减小诱导阻力,抑制前掠翼的发散倾向.但是该布局的设计参数选择需要气动,结构强度,气动弹性等多学科综合分析,多学科设计优化还需要提供相对于气动设计参数的敏度.探讨了一种翼尖连接机翼布局包含发散速压和变形在内的刚性和弹性气动特性,以及对气动设计参数的敏度,可供该布局的多学科设计优化参考.     

新型无尾联接翼布局气动特性研究

提出一种上下错开的无尾联接翼,即前翼或者后翼上反一定角度,使得前后翼垂直方向的相对距离从翼根处开始到翼梢处逐渐增大,以达到减小前后翼气动干扰的目的,搭接的小翼具有翼梢小翼作用,可有效减小诱导阻力。采用基于RANS方程的数值方法,研究了前后翼分别上反10°,20°和30°时对总体气动特性的影响,结果表明,当前翼上反且上反角为30°时其联接翼系统气动性能最佳。对该联接翼布局在Ma=0.85,0.95和1.20下进行了数值分析,结果表明,其升力系数变化较小,阻力系数在Ma0.85后才急剧增大,有应用于未来跨声速/超声速客机布局的潜力。     

大展弦比复合材料机翼结构建模与气动弹性分析

建立了具有任意截面形状的大展弦比复合材料翼的结构模型。研究了机翼的两种铺设方式：即周向均匀刚度配置（CUS）和周向反对称刚度配置（CAS）。对于复合箱梁情形,目前的结构建模方法正确性通过ANSYS有限单元软件得到了验证。为了研究具有NACA0012翼型的大展弦比复合材料机翼的气动弹性问题,利用线性ONERA空气动力模型来描述小攻角情形下的非定常空气动力载荷。最后,利用U—g法预示了机翼在各种复合层铺设角度下的颤振速度。     

水翼型水上飞机偏转机翼布局数值研究

针对水上飞机水面起飞过程阻力峰值较大,提出一种可偏转机翼水翼型水上飞机,飞机水面滑行时偏转机翼割划水面产生水动升力将飞机抬离水面,空中飞行时偏转机翼根据飞行条件可偏转角度。采用空气动力和水动力耦合求解并结合动力学平衡方程方法分析了该布局水动特性并进行空中巡航气动特性分析,同时计算同尺寸双浮筒型水上飞机,比较两种构型水动与气动特性。数值计算结果表明,水面起飞过程中双浮筒型水上飞机总阻力峰值约为水翼型水上飞机偏转机翼布局的1.97倍;飞机空中飞行时,偏转机翼偏转角为0°时气动性能最优且所受阻力低于双浮筒型水上飞机,从而证明了水翼型水上飞机偏转机翼布局能够有效提高水上飞机的水动与气动性能。     

Proportional fuzzy feed-forward architecture control validation by wind tunnel tests of a morphing wing

In aircraft wing design, engineers aim to provide the best possible aerodynamic performance under cruise flight conditions in terms of lift-to-drag ratio. Conventional control sur-faces such as flaps, ailerons, variable wing sweep and spoilers are used to trim the aircraft for other flight conditions. The appearance of the morphing wing concept launched a new challenge in the area of overall wing and aircraft performance improvement during different flight segments by locally altering the flow over the aircraft's wings. This paper describes the development and appli-cation of a control system for an actuation mechanism integrated in a new morphing wing structure. The controlled actuation system includes four similar miniature electromechanical actuators dis-posed in two parallel actuation lines. The experimental model of the morphing wing is based on a full-scale portion of an aircraft wing, which is equipped with an aileron. The upper surface of the wing is a flexible one, being closed to the wing tip; the flexible skin is made of light composite materials. The four actuators are controlled in unison to change the flexible upper surface to improve the flow quality on the upper surface by delaying or advancing the transition point from laminar to turbulent regime. The actuators transform the torque into vertical forces. Their bases are fixed on the wing ribs and their top link arms are attached to supporting plates fixed onto the flex-ible skin with screws. The actuators push or pull the flexible skin using the necessary torque until the desired vertical displacement of each actuator is achieved. The four vertical displacements of the actuators, correlated with the new shape of the wing, are provided by a database obtained through a preliminary aerodynamic optimization for specific flight conditions. The control system is designed to control the positions of the actuators in real time in order to obtain and to maintain the desired shape of the wing for a specified flight condition. The feasibility and effectiveness of the developed control system by use of a proportional fuzzy feed-forward methodology are demon-strated experimentally through bench and wind tunnel tests of the morphing wing model.     

跨声速机翼静气动弹性数值分析方法

本文给出一种以改进的跨声速守恒型全位势有限体积法为基础的机翼静气动弹性数值分析方法。改进发展了气动网格划分技术，使其对大后掠三角形机翼也能顺利适用。采用位移法计算机翼柔度影响矩阵。将非线性气动力与结构线化机翼弹性变形耦合迭代求解。当气动力和结构变形均收敛后，即求出弹性机翼的气动特性。通过算例计算，表明气动方法改进是成功的，弹性结果是合理的。跨声速范围弹性影响大，值得注意。     

连接翼布局直接力控制可能性的初步探索

对连接气动布局实现直接力控制的可能性进行了初步的探索。通过前、后机翼的长降舵面的不同偏转角组合，分别产生直接升力，侧力和阻力，提高了飞机的气动性能，并改善了控制的响应品质，给飞机提供了独立的姿态或轨迹控制的非同寻常的运动模态。增加头部鸭翼可进一步提高和改善了连接翼布局的直接升力特性。     

折叠翼变体飞行器非定常气动特性实验研究

折叠翼变体飞行器是一种可以在飞行中改变自身气动外形的新型飞行器。研制出了一种折叠翼变体飞行器的风洞实验模型,在风洞实验中测得了模型不同变体位置下的气动力以及进行变体运动时气动力的动态变化过程,并通过PIV实验手段获得模型周围的流场在变体运动过程中的变化情况。结果表明：在机翼变形过程中,折叠翼模型有明显的非定常气动现象产生,而且折叠变形的速度越大,非定常现象越明显。出现非定常现象的主要原因是变体运动对机翼前缘涡的影响。     

窄条翼布局导弹摇滚特性及流动机理

钝头体窄条翼布局导弹在大攻角下拥有极为优异的纵向气动特性,但横向容易失稳,做快速机动时容易诱发非指令的横向不稳定运动。通过开展高速风洞自由摇滚试验和数值模拟,研究了窄条翼导弹自由摇滚特性和流动机理,试验与计算吻合较好。研究发现:较大迎角时,窄条翼面积中心距离尾舵前缘根部5~6倍直径时,模型会进入极限环摇滚,窄条翼位置对模型稳定性有显著的影响,去掉窄条翼或尾舵时,模型均不会进入摇滚;模型空间流场特性表明,气流经过窄条翼时形成的片涡,对背风舵产生强烈的干扰,抑制了尾舵涡的形成和发展,使背风舵动态失稳,导致模型进入极限环摇滚。     

前/后掠机翼气动特性对比分析

基于NACA0012对称翼型设计了前掠机翼、后掠机翼和平直机翼,采用CFD方法计算了3种机翼的升力系数、阻力系数和俯仰力矩系数,通过压力云图和流线图分析了3种机翼的气动特性及流动机理。研究结果表明:前掠机翼上表面的流动是由翼尖流向翼根,翼根首先出现分离,而后掠机翼上表面的流动是由翼根流向翼尖,翼尖首先出现分离,平直机翼由于受翼尖涡的下洗影响,翼根首先出现分离;在30°斜掠角下,前掠机翼形成了机翼前缘涡,表现出旋涡流态气动特性。研究结果揭示了不同机翼之间的流动差异,有助于在飞行器设计过程中选择合适的气动布局。     

扑翼飞行器动力系统建模方法

为快速评估扑翼飞行器的航时,便于针对不同扑动翼进行动力系统设计与优化,逐步减少实物验证与试飞,加快扑翼飞行器的研制,基于实验数据参数辨识的方法建立了包含直流无刷电机、电调（ESC）、锂电池和扑动机构等扑翼飞行器动力系统组件的动态模型,其中电机模型相对误差小于10%,锂电池动态模型相对误差小于6%;提出了一种基于风洞试验气动数据和功率数据的扑动轴瞬时气动载荷半经验高精度建模方法,解决了气动载荷测量较为困难的问题,模型确定系数大于0.89;集成以上模型后的扑翼飞行器仿真系统还包含扑动翼周期平均气动模型、平尾气动模型和纵向控制模型,确保仿真在动态配平状态下进行,可进行全任务剖面航时仿真,航时仿真与实际试飞结果相比误差小于3%。集成的扑翼飞行器仿真系统采用模块化建模思想,各模型参数独立可调,能进一步应用于扑翼飞行器多学科优化等研究。