多段翼型低速流场与气动特性数值计算研究

在结构化网格求解RANS方程的基础上,将嵌套网格技术应用在低速绕流气动特性计算中,并以NLR-7301两段翼型和某运输机5段翼型在起飞构型下对低速绕流流场进行数值模拟,将气动特性及流场特性的数值模拟数据与对接网格计算以及风洞实验数据进行了比较.结果表明,该气动特性计算方法有着较高的精度和可靠性.     

树脂基复合材料制造过程温度变化模拟研究

本文在树脂基复合材料树脂基体固化动力学研究的基础上,将固化反应热通过固化反应动力学方程引入热传导方程,模拟实际工艺条件建立了复合材料固化过程的温度分布模型,将模拟计算值和实际测量值进行了比较,发现所建立的复合材料制造过程温度分布模拟技术可以准确模拟环氧和双马复合材料在制造过程中的温度变化.     

基于伴随技术的超音速反舰导弹末端机动突防的脱靶量分析

采用伴随技术,得到了确定性误差条件下反舰导弹末端机动突防的稳态脱靶量解析解。利用该解析解,得到了各种末端机动的脱靶量曲线。结果表明,两种非平面机动方式比平面机动方式有更大的脱靶量,从而有更好的突防效果。     

Modeling of LEO orbital debris populations for ORDEM2008

The NASA Orbital Debris Engineering Model, ORDEM2000, is in the process of being updated to a new version: ORDEM2008. The data-driven ORDEM covers a spectrum of object size from 10 μm to greater than 1 m, and ranging from LEO (low Earth orbit) to GEO (geosynchronous orbit) altitude regimes. ORDEM2008 centimeter-sized populations are statistically derived from Haystack and HAX (the Haystack Auxiliary) radar data, while micron-sized populations are estimated from shuttle impact records. Each of the model populations consists of a large number of orbits with specified orbital elements, the number of objects on each orbit (with corresponding uncertainty), and the size, type, and material assignment for each object. This paper describes the general methodology and procedure commonly used in the statistical inference of the ORDEM2008 LEO debris populations. Major steps in the population derivations include data analysis, reference-population construction, definition of model parameters in terms of reference populations, linking model parameters with data, seeking best estimates for the model parameters, uncertainty analysis, and assessment of the outcomes. To demonstrate the population-derivation process and to validate the Bayesian statistical model applied in the population derivations throughout, this paper uses illustrative examples for the special cases of large-size (>1 m, >32 cm, and >10 cm) populations that are tracked by SSN (the Space Surveillance Network) and also monitored by Haystack and HAX radars operating in a staring mode.     

基于Delaunay图映射的动弹网格技术及其应用

在多块混合网格的基础上发展了一套基于Delaunay图映射方法的动弹网格技术,实现了针对气动弹性计算的网格变形运动方法,并使用基于多块混合网格的RANS方程的有限体积法耦合结构静平衡方程,针对大展弦比无人机在实际使用中可能出现的显著的静气动弹性问题进行了计算、分析和研究。研究结果表明,所发展的动弹网格方法为粘性混合网格的变形提供了较好的解决方案;RANS方程解算器具有较高的精度和较强的适用性,具备求解粘性流体与结构耦合等复杂航空气动弹性问题的能力。     

鸭翼电磁散射特性分析与RCS减缩方法研究

利用多层快速多极子方法计算鸭翼模型雷达散射截面(RCS),分析了鸭翼前缘后掠角和展长对鸭翼RCS值的影响,并根据计算结果拟合了随前缘后掠角和展长变化的鸭翼RCS曲线。建立飞机模型,计算了鸭翼不同偏转角时飞机的RCS值,研究鸭翼偏转对飞机头向RCS的影响。计算结果表明,鸭翼偏转会显著增大飞机头向RCS,影响飞机隐身性能。根据计算结果分析推导出鸭翼纵向操纵力矩、飞机头向RCS和鸭翼几何参数之间的函数关系,为鸭翼的隐身和气动优化设计提供了技术基础。对鸭翼上使用吸波材料的情况进行计算,结果验证了在鸭翼上涂敷吸波材料能够大幅降低飞机头向RCS。     

外吹式襟翼动力增升数值模拟方法研究

针对某运输机简化模型,采用数值模拟分析的方法开展了外吹式襟翼动力增升效能分析研究。本文首先对单独的发动机模型和不带动力装置的增升模型进行数值模拟,计算结果均与实验值吻合良好,表明动力增升效能分析所采用的边界条件处理方法、网格生成策略以及流场计算方法的合理性及适用性。在此基础上对动力增升构型在带发动机喷流效应和通气短舱的两种情况进行数值模拟与对比分析。结果显示其增升效果显著、流场结果合理。表明本文所形成的计算方法与技术思路可靠的、有效的,方法对大型运输机外吹式襟翼动力增升系统的设计分析具有一定的应用价值。     

基于卫星共视的罗兰C导航系统原子频标时间同步

介绍了CV技术的基本原理和罗兰C系统原子频标资源的使用状况,并通过引入系统融合和CV技术,对比对数据进行检测校验,最终实现了罗兰C导航系统原子频标与UTC时间基准同步。     

基于全息激光技术的纳米级分辨力位移传感器设计

介绍了一种新型的基于全息激光技术的纳米位移传感器。全息激光技术最早广泛应用在CD,DVD等系统中,用以读取光盘信息,并对光盘进行寻迹、聚焦等。文中以采用全息激光技术的全息激光头为核心器件,结合少量光学元件,设计出一种纳米分辨力级位移传感器,并通过实验验证了设计结果。     

Hardware-in-the-loop simulations of GPS-based navigation and control for satellite formation flying

A relative navigation and formation control algorithm for satellite formation flying was developed, and a hardware-in-the-loop (HIL) simulation testbed was established and configured to evaluate this algorithm. The algorithm presented is a relative navigation estimation algorithm using double-difference carrier-phase and single-difference code measurements based on the extended Kalman filter (EKF). In addition, a state-dependent Riccati equation (SDRE) technique is utilized as a nonlinear controller for the formation control problem. The state-dependent coefficient (SDC) form is formulated to include nonlinearities in the relative dynamics. To evaluate the relative navigation and control algorithms developed, a closed-loop HIL testbed is configured. To demonstrate the performance of the testbed, a test formation flying scenario comprising formation acquisition and keeping in a low earth orbit (LEO) has been established. The relative navigation results from the closed-loop simulations show that a 3D RMS of 0.07 m can be achieved for position accuracy. The targeted leader–follower formation flying in the along-track separation of 100 m was maintained with a mean position error of approximately 0.2 m and a standard deviation of 0.9 m. The simulation results show that the HIL testbed is capable of successful demonstration of the GPS-based satellite autonomous formation flying mission.