可变形翼战术导弹飞行动力学联合仿真研究

基于集中质量假设发展的一套适于可变形翼导弹的多体运动模型,以附加惯性项及快变气动参数的形式来反映弹翼变形对导弹动态特性的影响,涉及交叉求解不同弹翼外形对应的气动特性及运动方程.由此提出的一种基于Missile DATCOM与MATLAB/SIMULlNK的联合仿真方法,应用于典型轴对称导弹的变翼动态特性研究中,快速有效...     

柔性机翼阵风响应与被动减缓研究

高空长航时无人机的机翼展弦比大、柔性较强,飞行过程中极易受到阵风的影响。文章以几何精确本征理论建立结构模型,耦合 Pitt-Peters动力入流理论建立柔性机翼非线性气弹模型,研究了柔性机翼阵风响应以及翼尖被动阵风减缓效应。采用空间 -时间平行的有限元离散方法,将气弹方程转化为一阶微分代数方程,Newton-Raphson和 Generalized-α算法分别用于静态变形和动态响应的求解,通过算例研究了离散阵风载荷下柔性机翼的阵风响应,结果表明翼尖被动阵风减缓装置对机翼变形有明显的减缓效果。     

低轨卫星月影事件预报优化

针对卫星月影问题,提出了一种低轨卫星优化的月影预报策略,可以有效提高目前低轨卫星在轨管理时对月影事件预报的效率.结合仿真对产生月影事件的太阳、地球、月球的三体关系进行了分析,首先给出了月影产生的解析分析方法,并通过对一个三维月影影响模型的分析,得到了月影影响区间的判定要素——月影临界角;然后进一步通过对月影临界角的分析,提出了基于太阳与白道面的位置关系和月影临界角对低轨卫星月影事件的优化预报方法;最后基于大量的随机低轨卫星场景对本方法的正确性进行了验证.研究结果表明,此方法能够较大地提高月影预报效率,可以将月影预报频率从每月1次降低到每年2次,从而简化了低轨卫星在轨运行管理的任务复杂度,为卫星的在轨可靠运行提供支持.     

Flapping wing micro-aerial-vehicle:Kinematics,membranes, and flapping mechanisms of ornithopter and insect flight

The application of biomimetics in the development of unmanned-aerial-vehicles (UAV) has advanced to an exceptionally small scale of nano-aerial-vehicles (NAV), which has surpassed its immediate predecessor of micro-aerial-vehicles (MAV), leaving a vast range of development possi-bilities that MAVs have to offer. Because of the prompt advancement into the NAV research devel-opment, the true potential and challenges presented by MAV development were never solved, understood, and truly uncovered, especially under the influence of transition and low Reynolds number flow characteristics. This paper reviews a part of previous MAV research developments which are deemed important of notification; kinematics, membranes, and flapping mechanisms ranges from small birds to big insects, which resides within the transition and low Reynolds number regimes. This paper also reviews the possibility of applying a piezoelectric transmission used to pro-duce NAV flapping wing motion and mounted on a MAV, replacing the conventional motorized flapping wing transmission. Findings suggest that limited work has been done for MAVs matching these criteria. The preferred research approach has seen bias towards numerical analysis as com-pared to experimental analysis.     

Dynamic modeling and analysis of vortex filament motion using a novel curve-fitting method

Applications of a novel curve-fitting technique are presented to efficiently predict the motion of the vortex filament, which is trailed from a rigid body such as wings and rotors. The governing equations of the motion, when a Lagrangian approach with the present curve-fitting method is applied, can be transformed into an easily solvable form of the system of nonlinear ordinary differential equations. The applicability of Be′zier curves, B-spline, and Lagrange interpolating polynomials is investigated. Local Lagrange interpolating polynomials with a shift operator are proposed as the best selection for applications, since it provides superior system characteristics with minimum computing time, compared to other methods. In addition, the Gauss quadrature formula with local refinement strategy has been developed for an accurate prediction of the induced velocity computed with the line integration of the Biot–Savart law. Rotary-wing problems including a vortex ring problem are analyzed to show the efficiency, accuracy, and flexibility in the applications of the proposed method.     

视觉测振技术在柔性太阳翼模态试验中的应用

针对8 m×5 m的柔性太阳翼在倒立状态下进行模态试验,设计数字摄像视觉测振系统,基于图像特征跟踪法实现了从相机标定、图像采集、信息提取到三维振动数据获取的过程,通过工况模态辨识方法获取了柔性太阳翼模态频率及振型等动力学参数。并考虑空气和重力影响建立太阳翼有限元模型,通过与基于基恩士激光位移传感器的传统模态试验结果及仿真分析结果进行对比,验证了基于视觉测振工况模态试验方法的准确性,为柔性太阳翼在轨模态辨识奠定基础。     

基于线化稳定性理论的后掠翼边界层内横流稳定性研究

采用Mack方法求解忽略曲率和压缩性的三维线化稳定性方程（Orr-Sommerfeld方程）,针对无限展长后掠翼,计算分析边界层内不同波长横流驻波沿弦向的放大率,确定最不稳定波的波长。计算结果与参考文献中的实验结论和计算结果符合较好,表明该方法能够准确的预测出最不稳定波的波长,可以用来指导横流驻波主导下的后掠翼流动稳定性问题研究。     

低雷诺数条件下微型无人机机翼形状的研究

利用CFD软件FLUENT,通过Spalart-Allmaras模型、低Reynolds和二层模型这3种湍流模型对正八边形机翼平面布局进行绕流分析并与试验数据进行对比,选择了低Reynolds湍流模型对4种微型无人机机翼平面形状的低雷诺数气动特性进行模拟分析,结果表明,矩形布局和反齐默曼布局是微型无人机比较理想的设计选择.     

小展弦比飞翼布局作战飞机垂直面机动性研究

比较分析了某小展弦比飞翼布局作战飞机与典型的常规布局战斗机F16在亚、跨、超声速范围的气动特性,相对而言,飞翼布局飞机具有较大的升阻比和较低的翼载荷.计算并分析了该飞翼布局作战飞机与F16在垂直机动面内的平飞加速性能和跃升性能,得到了由于布局和气动特性不同引起的飞翼布局作战飞机机动性的新特点.研究结果对飞翼布局作战飞机的设计和作战使用均具有一定的参考意义.     

基于遗传算法的旋转机翼飞机机翼优化设计

将基于实数编码的遗传算法与能准确描述翼型粘性流动的NS方程以及旋翼气动分析模型结合起来,以旋翼最大悬停效率作为优化设计的目标对旋转机翼飞机的机翼进行优化设计,设计结果表明通过优化设计旋翼的气动性能得到了提高,达到了优化设计的目的,旋翼优化设计方法是可行的.