Regularities between kinematic and aerodynamic characteristics of flexible membrane wing

The kinematic characteristics of flexible membrane wing have vital influences on its aerodynamic characteristics. To deeply explore the regularities between them, time-resolved aerodynamic forces and deformations at different aeroelastic parameters and angles of attack(α) were measured synchronously by wind tunnel experiments. The membrane motion can be mainly divided into two states at α > 0° with various lift-enhancement regularities: Deformed-Steady State(DSS)at pre-stall, and Dynamic Bala...     

空间站柔性太阳电池翼对日跟踪控制

空间站柔性太阳电池翼高稳定对日跟踪驱动控制,对于保障空间站长期在轨能源安全和平稳运行具有重要意义。在推导柔性太阳电池翼动力学模型、柔性体模态分析和截断、Alpha对日定向装置机电系统模型、非线性传动系统模型的基础上,对空间站柔性太阳电池翼对日跟踪控制系统进行设计。采用Heaviside五次样条变速规划、位置和速度两级闭环、速度环陷阱滤波器柔性振动抑制的组合方案,实现空间站柔性太阳电池翼高稳定驱动控制。通过对典型工况的仿真校核,验证所设计的控制方案可实现跟踪精度优于0.3°、速度偏差±0.005(°)/s、稳定度优于7%@0.065(°)/s的性能指标。同时,Alpha对日定向装置的启动和变速过程中驱动力矩不大于30 N·m,稳速运行期间驱动力矩不大于5 N·m。各项性能指标要好于国际空间站Alpha对日定向装置,满足使用要求。     

Delaying stall of morphing wing by periodic trailing-edge deflection

Morphing wings can improve aircraft performance during different flight phases. Recently research has focused on steady aerodynamic characteristics of the morphing wing with a flexible trailing-edge, and the unsteady aerodynamic and stall characteristics in the deflection process of the morphing wing are worthy further investigation. The effects of the angle of attack and deflection rate on aerodynamic characteristics were examined, and based on the aerodynamic characteristics of the morphing wing, a method was developed to delay stall by using the flexible periodic trailing-edge deflection. The numerical results show that the lift coefficients in the deflection process are smaller than those in the static situation at small angles of attack, and that the higher the deflection rate is, the smaller the lift coefficients will be. On the contrary, at large angles of attack, the lift coefficients are higher than those in the static case, and they become larger with the increase of the deflection rate. Further, the periodic deflection of the flexible trailing-edge with a small deflection amplitude and high deflection rate can increase lift coefficients at the critical stall angle.     

牛顿流理论及其在谐振机翼上的应用

根据牛顿流理论,文中讨论了高马赫数、任意迎角、一般剖面在均匀来流中作沉浮和俯仰谐振的翼型和机翼。导得翼型和机翼表面的牛顿撞击压强和安定性导数公式。给出楔、平板三角翼、双抛物线剖面三角翼俯仰刚性导数(-C_(mθ)和阻尼导数(-C_(m))的数值例子。数值结果与现有的牛顿-布兹曼流理论、薄激波层理论、欧拉方程摄动理论的结果作了比较,算例表明本文的结果令人满意。     

细长三角翼摇滚非定常流动特性

对前缘后掠角为80°的细长三角翼,迎角为30°和40°时不同滚转角下前缘涡的静态特性,及摇滚过程中的动态旋涡特性进行了流态显示和摄影记录。结果表明:在相同滚转角下,静态和动态情况下旋涡特性有相当大的差别;相对于静态而言翼摇滚过程中存在着旋涡特性的滞后效应;摇滚过程中旋涡垂向位置的滞后是明显的,而展向位置的滞后很小;还发现翼摇滚起始角对旋涡特性有较大影响.     

仿蜻蜓扑翼飞行器机构设计及气动力研究

针对蜻蜒扑翼飞行机理与鸟类单翼飞行机理的不同,设计了一种双翅翼空间四杆扑翼机构,提出了一种非对称刚度柔性翅翼.该翅翼上拍时刚度较小,下拍时刚度较大,上拍时翅翼变形比下拍时翅翼变形大,空气阻力较小,可以提高每个拍动周期中的等效升力,从而有效减小飞行器飞行时的能耗速度,提高飞行效率.基于非定常空气动力学原理,建立了仿蜻蜒扑翼飞行器的动力学模型,对双翼挥拍过程中不同相位差下的升阻特性进行了分析,可为飞行过程中扑动模式的选择提供参考.     

跨音速三维机翼及翼身组合体非守恒型全位势流AF3算法

 本文对跨音速非守恒型全位势流,用Baker的快速有限差分法,改变其网络拓扑,研制出分析机翼及翼身组合体跨音速绕流的实用程序。其中包括:对“C-H”型贴体坐标网格提出AF3算法的具体实施方案取得了快速收敛效果;采用张量形任意曲线坐标上的非守恒全位势方程,使得程序中跨音速求解部分既能用于分析单独机翼又能用于翼身组合体跨音速绕流计算。     

前掠翼气动布局中鸭翼高度影响的实验

基于前掠翼-鸭式前翼布局的风洞测力实验,分析了距离主机翼较远的鸭翼相对于主机翼的高度对布局纵向气动性能的影响.基于主机翼根弦长的雷诺数约为1.44×10⁵.实验结果表明,较大的主机翼前掠角与较低的鸭翼配合,产生的升力系数增量比较显著.低于主机翼的鸭翼将加强前掠翼布局的缓失速特性.鸭翼增大升力的同时也增大了阻力;大攻角时,鸭翼带来的阻力增量较大.高于主机翼的鸭翼对最大升阻比的改善较多,但也不宜过高.主机翼前掠角较小时,鸭翼改善和提高升阻比的效果比较明显.     

尖顶襟翼长度对三角翼前缘涡破裂的影响

为了抑制三角翼前缘涡破裂的发生,研究了大攻角下(30°～50°)尖顶襟翼对70°三角翼前缘涡破裂的影响.在静态实验情况下,尖顶弯折对三角翼前缘涡破裂影响的参数有2个:尖顶襟翼弯折的角度及其长度.染色液流态显示结果表明:尖顶襟翼的向下弯折减小了靠近襟翼翼面的有效攻角,从而推迟了前缘涡破裂的发生,涡破裂位置随弯折角的变化呈非线性变化且弯折襟翼越长效果越好,α=35°时两个弯折组合的效果要比单个弯折的好.