双三角翼外翼前缘钝化对涡流特性的影响

通过风洞试验，利用７孔探头对７５°／４５°和７５°／６０°两种典型双三角翼进行了空间流场测量，研究了双三角翼前缘形状对大迎角涡流特性的影响．试验结果表明，双三角翼外翼前缘钝化使双涡态的双三角翼内、外翼涡互相靠拢、增加干扰，当出现合并涡态时，使合并涡涡核向内下方偏移；外翼前缘钝化使外翼涡或合并涡的Ｃｐ０、Ｖｘ较尖前缘时为高，最终使外翼涡或合并涡推迟破裂．     

基于连续覆盖特性分析的星座设计

研究了需要对地面目标进行连续覆盖的星座的设计问题．首先推导了对覆盖性能有重要影响的星间覆盖间隔时间和轨道面覆盖间隔时间的计算公式，通过算例针对不同配置的星座进行了计算，使用工程仿真软件STK验证了分析结果．通过理论分析、算例计算以及工程仿真为该类型星座设计提供了理论指导。     

喷管扩张段烧蚀的“台阶效应”计算

当喉衬和扩张段内衬采用具有不同烧蚀率的材料时,常出现“台阶效应”.本文以气动热化学烧蚀机理为基楚,提出应用适当的对流换热和加剧的化学反应计算对台阶效应区进行修正的方法,使台阶效应区的烧蚀率预示更切合实际工况.     

双向比对高精度物理时间同步方法

提出一种面向未来卫星在轨应用的闭环物理高精度时间同步方法。比较了所提方法与其他时间同步方法的区别与优势，建立了远程系统时间同步基本模型与误差传递模型，基于双向测距和时间传递技术分析了高精度钟差获取原理，给出了时钟调整环路的时域频域参数依赖关系。完成了高精度时间同步地面试验系统构建，测试了开环非调钟状态下钟差测量精度误差、闭环调钟状态下时间同步准确度误差以及长时运行情况下的时间同步监测结果。测试结果表明，该方法能够实现优于1 ns量级的时间同步，为高精度时间同步技术研究提供了新的途径。     

Aerodynamic performance enhancement for flapping airfoils by co-flow jet

Introducing active flow control into the design of flapping wing is an effective way to enhance its aerodynamic performance. In this paper, a novel active flow control technology called Co-Flow Jet (CFJ) is applied to flapping airfoils. The effect of CFJ on aerodynamic performance of flapping airfoils at low Reynolds number is numerically investigated using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulation with Spalart-Allmaras (SA) turbulence model. Numerical methods are validated by a NACA6415-based CFJ airfoil case and a S809 pitching airfoil case. Then NACA6415 baseline airfoil and NACA6415-based CFJ airfoil with jet-off and jet-on are simulated in flapping motion, with Reynolds number 70,000 and reduced frequency 0.2. As a result, CFJ airfoils with jet-on generally have better lift and thrust characteristics than baseline airfoils and jet-off airfoil when C_μ is greater than 0.04, which results from the CFJ effect of reducing flow separation by injecting high-energy fluid into boundary layer. Besides, typical kinematic and geometric parameters, including the reduced frequency and the positions of the suction and injection slot, are systematically studied to figure out their influence on aerodynamic performance of the CFJ airfoil. And a variable C_μ jet control strategy is proposed to further improve effective propulsive efficiency. Compared with using constant C_μ, an increase of effective propulsive efficiency by 22.6% has been achieved by using prescribed variable C_μ for NACA6415-based CFJ airfoil at frequency 0.2. This study may provide some guidance to performance enhancement for Flapping wing Micro Air Vehicles (FMAV).     

一次民机飞行中甚高频通信不稳定的排故

针对某型号民用飞机甚高频通信系统在飞行中出现断续故障的情况，对系统的架构进行描述，分析了故障产生的机理，提出了排故思路，记述了排故过程，并总结了甚高频通信系统的设计要点和工艺要点。     

A general calculation method to specify center-of-buoyancy for the stratospheric airship with multiple gas cells

As the lighter-than-air (LTA) flight vehicle, the stratospheric airship is a desirable platform to provide communication and surveillance services. During the ascent from sea-level to the mission altitude, the volume of the lifting gas may change significantly, which will result in the change of the center-of-buoyancy (CB). A general calculation method is developed to specify CB for the stratospheric airship with a double-ellipsoid hull and an arbitrary number of the gas cells. The cross-section-integral (CSI) method is used as a basic calculation scenario to specify CB. Considering the complexity in determining the boundary between the helium and air in the gas cell, a searching algorithm is put forward and the specification of CB can be conducted by the iterative calculation. As an important application, the stable condition of the pitch angle is analyzed when the change of CB is involved. Under different initial configurations, the stable pitch angle of the stratospheric airship during the ascent is specified and compared, which shows the advantages of the multi-gas-cell configuration. The results of this paper may provide an important reference for the engineering application of the stratospheric airship.     

静止轨道卫星通信链路的预算与分析

星地链路计算作为卫星通信的重要技术，是卫星通信系统设计的基础和理论依据，直接决定了卫星通信系统的链路通信质量。由于影响卫星链路的因素很多，设计中存在一处不合理即使得整条星地链路不可用，造成巨大的损失。而且在实际设计中无法做到最理想的链路状态，往往需要在某方面有所取舍，这也是链路计算中的一大难点。基于目前国际通用的链路计算方法，将星地链路上下行拆分，独立计算，综合分析，再结合实际工程经验，分析和计算实际工程案例，针对不同的链路配置给出相应合理的设计方法，可作为静止轨道通信卫星星地链路计算分析的参考。     

微分法在定位误差分析与计算中的应用

介绍了微分法分析计算定位误差的原理和适用范围,通过生产实例分析,证明了该方法在解决多误差因素定位误差分析与计算中的简便与快捷,从而有效简化了复杂定位方案定位误差的分析与计算,提高了夹具的设计效率。