基于迭代物理光学和等效边缘电流方法的S形进气道雷达散射截面研究

为了研究进口形状对S形进气道唇口边缘绕射场与其腔体内部散射场电磁特性的影响,在S形进气道偏心距、面积变化规律、中心线变化规律不变的条件下,采用迭代物理光学法(IPO)与等效边缘电流法(EEC)方法,对圆形、椭圆形、矩形、菱形、W形等5种不同进口形状的S形进气道进行了雷达散射截面(RCS)的数值分析.结果表明,进口形状对进气道的RCS特性影响较大;在较大的探测角范围内,W形进口S形进气道的RCS值明显低于其它进口形状的S进气道;菱形进口进气道的RCS在唇口未做修型S形进气道中最低.W形唇口修型可有效降低唇口边缘绕射场的RCS;而在负探测角时,斜切唇口修型可大大降低S形进气道总散射场的RCS.     

Integrated optimization analyses of aerodynamic/stealth characteristics of helicopter rotor based on surrogate model

Based on computational fluid dynamics(CFD)method,electromagnetic high-frequency method and surrogate model optimization techniques,an integration design method about aerodynamic/stealth has been established for helicopter rotor.The developed integration design method is composed of three modules:integrated grids generation(the moving-embedded grids for CFD solver and the blade grids for radar cross section(RCS)solver are generated by solving Poisson equations and folding approach),aerodynamic/stealth solver(the aerodynamic characteristics are simulated by CFD method based upon Navier–Stokes equations and Spalart–Allmaras(S–A)turbulence model),and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics(PO),equivalent currents(MEC)and quasi-stationary(MQS),and integrated optimization analysis(based upon the surrogate model optimization technique with full factorial design(FFD)and radial basis function(RBF)),an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted.Firstly,the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out,then time–frequency domain grayscale with strong scattering regions of rotor have been given.Meanwhile,the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed.Furthermore,by choosing suitable object function and constraint condition,the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.     

光学加工射频离子源的去除函数与稳定性研究

在研究了射频离子源的结构、工作原理和性能的基础上,进行了光学镜面抛光离子束的去除效率与稳定性测试。实验结果表明射频离子源去除函数的形状为回转高斯形,利用Φ15mm的栅网,在靶距为30mm、离子能量900eV时,去除函数的峰值去除率为194nm/min,体积去除率为19.2×10-3mm3/min,半峰全宽值为9.2mm;并且去除函数的峰值去除率与体积去除率的变化均在3%以内,半峰全宽值的变化在1.7%以内。因此,射频离子源具有光学镜面抛光加工所需的去除效率,而且射频离子源具有好的稳定性,具备光学加工的潜能。     

离子推进器和流量控制单元

使用电动电源线确保使用电力,它等于几十千瓦。 建议它应该高达10000秒。 Keldysh研究中心（KeRC）正在开发推进系统。 35千瓦离子推进器和FCU-500流量控制单元。 IT-500和FCU-500的2000小时寿命测试是 离子推进器大部分运行2018小时,使用40千克氙气。 本文还介绍了磁场和离子光学的改进以及石墨网格的发展状况。     

A Celestial Analytic Positioning Method by Stellar Horizon Atmospheric Refraction

This article, in allusion to the limitation of conventional stellar horizon atmospheric refraction based on orbital dynamics model and nonlinear Kalman filter in practical applications, proposes a new celestial analytic positioning method by stellar horizon atmospheric refraction for high-altitude flight vehicles, such as spacecraft, airplanes and ballistic missiles. First, by setting up the geometric connexion among the flight vehicle, the Earth and the altitude of starlight refraction, an expression for the relationship of starlight refraction angle and atmospheric density is deduced. Second, there are produced a novel measurement model of starlight refraction in a continuous range of altitudes (CRA) from 20 km to 50 km on the basis of the standard atmospheric data in stratosphere, and an empirical formula of stellar horizon atmospheric refraction in the same altitudes against the tangent altitude. Third, there is introduced a celestial analytic positioning algorithm, which uses the least square differential correction instead of nonlinear Kalman filter. The information about positions of a flight vehicle can be obtained directly by solving a set of nonlinear measurement equations. The stellar positioning algorithm adopts the characteristics of stellar horizon atmospheric refraction thereby removing needs for orbit dynamics models and priori knowledge of flight vehicles. The simulation results evidence the validity of the proposed stellar positioning algorithm.     

仿生流体力学实验中的运动控制系统

在搭建仿生流体力学实验平台的过程中,针对仿生模拟运动要求高精度、多自由度等特点建立了一套运动控制系统,能够实现(最多)4轴同步控制,经测试满足实验精度要求.     

采用640×512元探测器的机载红外系统设计

连续变焦红外探测系统具有在变焦过程中不会丢失跟踪目标的优点。针对中波640×512元红外焦平面凝视探测器设计了一套1∶20小型高分辨率连续变焦红外系统,对红外系统的设计、非均匀校正方法进行了深入研究,对系统的灵敏度（NETD和MRTD）进行了分析计算和测试。试验结果表明,使用640×512元探测器的连续变焦红外系统具有分辨率高、灵敏度高、体积小和像质好等特点,满足设计要求,可用于机载光电探测和跟踪系统。     

布撒器雷达截面计算与测量

用物理光学法计算了布撒器的雷达截面,并与外场测量结果进行了比较。计算的RCS～θ曲线与测量的RCS～θ曲线变化趋势相同,在典型方向上的计算结果与测量结果比较吻合。表明镜面回波在强度上占绝对优势的目标RCS计算中,物理光学法可以给出工程上可用的结果。     

旋转雾场粒子分布的全息测量

介绍了用高斯光束照射光栅而形成的衍射光场照明粒子场的同轴全息方法可以有效地测量旋转流雾化场横截面上的ＳＭＤ分布。文中描述了照明光场的特点；简要地讨论了低噪声，无孪生象的原因；介绍了全息图的显示和判读系统。完成了对１９个喷嘴、７６个截面、１６００多个采样点的测量。为密度较高的粒子场提供了有实用价值的测量结果。最后给出了Ｎｏ．１号喷嘴四个截面上ＳＭＤ分布曲线     

机翼的雷达散射截面计算

飞机雷达散射特性是影响飞机生存力的重要因素之一。在镜面反射得到控制后，机翼成为影响飞机雷达散射特性的重要散射源。利用物理光学和物理绕射理论计算翼的雷达散射截面。在计算中不仅考虑了机翼表面和后缘尖劈的散射，而且也考虑了由于面分块造成翼面不连续而形成的尖劈散射。