鸭翼的雷达散射截面影响研究

针对鸭翼对鸭式布局战斗机整机的雷达散射截面（RCS）影响进行了较详细的研究与分析。首先，分析了鸭翼的散射机理，然后运用多层快速多极子方法（MLFMM）进行特定模型的整机外形RCS计算，通过鸭式布局和常规布局的RCS对比，分析了鸭翼散射对整机RCS的影响，包括鸭翼偏转状态下对整机的影响。然后，通过试验方法研究了鸭翼边缘散射和对缝散射的影响以及相应的抑制措施。研究结果表明，对鸭翼散射进行抑制或消除之后，鸭式布局完全可以应用于高隐身飞机的布局设计，其隐身性能与常规布局相当。最后，总结得出鸭翼隐身设计的指导性原则。     

基于频率选择表面(FSS)技术的微小卫星隐身天线罩设计

天线是卫星的强散射源,降低天线的RCS是卫星隐身设计的重要研究课题之一,本文提出了一种基于频率选择表面技术的微小卫星天线罩设计方案,可有效降低卫星天线的RCS。首先针对隐身天线罩设计要求,设计天线罩壁,包括各层介质的介电常数、厚度等。然后设计附着在罩壁上的FSS屏。进一步制作天线罩实物,通过在微波暗室进行天线罩扫频测试,实际测量该天线罩的频率响应特性,并测试星上天线方向图。结果表明,本文提出的天线罩设计可满足微小卫星天线在给定频段的阻带特性,并保持在给定正常工作频段的通带特性,说明该微小卫星隐身天线罩设计是有效的。     

噪声调制连续波雷达信号波形射频隐身特性

雷达信号波形的射频(RF)隐身性能是雷达系统能否适应现代战场环境的重要因素,雷达射频隐身信号波形设计是现代雷达系统设计中的重要课题.首先,在介绍随机噪声信号雷达原理的基础上,基于Schleher截获因子阐述了噪声调制连续波雷达信号波形的射频隐身特性.然后,分析了高斯噪声相位和频率调制连续波雷达输出自相关函数和高斯噪声相...     

Composite impact vector control based on Apollo descent guidance

A new three-dimensional missile guidance law to control the impact vector against a stationary target is proposed. The composite guidance law has two well-known components: Apollo descent guidance and trajectory shaping guidance. These respectively linear and planar guidance laws are combined to achieve a specified impact direction. The main idea is to define an impact plane and to steer the missile onto this plane using Apollo descent guidance while concurrently performing trajectory shaping wi...     

钨板加热旋压模具设计及加热方法研究

本文主要论述纯钨板成形时模具及靠板的设计、调试，并对成形过程中模具及钨板的加热方法、工艺参数进行了分析。     

隐身等离子体的几个相关问题研究

在目标的雷达隐身方面,等离子体具有巨大的应用潜力。对隐身应用时产生等离子体的气压、放电气体种类以及放电方式进行了论述。指出在大气压下,适宜利用惰性气体放电来产生等离子体。而目前许多文献中所报道的隐身等离子体的产生方法离工程应用还有一定距离,还有许多问题亟待解决。     

Convex shaping process simulation during counter-rotating electrochemical machining by using the finite element method

In counter-rotating electrochemical machining(CRECM), a revolving cathode tool with hollow windows of various shapes is used to fabricate convex structures on a revolving part. During this process, the anode workpiece and the cathode tool rotate relative to each other at the same rotation speed. In contrast to the conventional schemes of ECM machining with linear motion of a block tool electrode, this scheme of ECM is unique, and has not been adequately studied yet. In this paper, the finite element method(FEM) is used to simulate the anode shaping process during CRECM, and the simulation process which involves a meshing model, a moving boundary,and a simulation algorithm is described. The simulated anode profiles of the convex structure at different processing times show that the CRECM process can be used to fabricate convex structures of various shapes with different heights. Besides, the variation of the inter-electrode gap indicates that this process can also reach a relative equilibrium state like that in conventional ECM. A rectangular convex and a circular convex are successfully fabricated on revolving parts. The experimental results indicate relatively good agreement with the simulation results. The proposed simulation process is valid for convex shaping prediction and feasibility studies as well.     

一体化红外抑制器遮挡和出口修型对后机身表面温度和红外辐射特性的影响

针对与后机身融合的一体化红外抑制器模型,采用数值模拟的方法研究了内部遮挡和出口修型对后机身表面温度场和红外辐射特性的影响。在混合管外部采用遮挡套或曲面遮挡板可有效降低后机身侧壁面对应混合管后段的局部区域最高温度,两种方式均可有效降低水平探测面以及铅垂面上方3~5 μm波段和8~14 μm波段红外辐射强度峰值;然而,加装遮挡套方式会影响旋翼下洗气流的导入,使3~5 μm波段的红外辐射强度在铅垂面下方较基准模型有小幅的增加。对后机身排气口进行出口修型,虽然对降低后机身3~5 μm和8~14 μm波段红外辐射强度的作用效果并不显著,但可以有效消除排气出口下方壁面的高温区,其中采用狭窄流道引气冷却方式可以使得后机身侧壁仅高于环境温度10 K左右。     

Key Parameters and Conceptual Configuration of Unmanned Combat Aerial Vehicle Concept

The nature and characteristics of attack unmanned combat aerial vehicle (UCAV) are analyzed. The principles of selecting takeoff thrust-weight ratio and takeoff weight of attack UCAV are presented by analyzing the statistical data of weights for various main combat aircraft. The UCAV airborne weapons are analyzed, followed by the preliminary estimation of the payload weight. Various typical engines are analyzed and one of them is selected. Then the takeoff weight of the UCAV is determined. Based on some basic parameters and assumptions, the qualitative decomposition calculation for takeoff weight is completed. The key factors for obtaining longer endurance of aircraft with small aspect ratio configuration are found to be high lift-drag ratio and internal space. On the basis of the conclusions mentioned above, a highly blended flying-wing plus lifting body concept is proposed. According to this concept, the UCAV configuration is designed and optimized. Finally, the UCAV configuration with small aspect ratio, high lift-drag ratio, and high stealth characteristic is obtained.     

Collective trajectory planning for satellite swarm using inter-satellite electromagnetic force

The inter-satellite electromagnetic force presents several significant advantages that help to expand its space applications to the multi-satellite missions gradually. For a satellite swarm, whether the electromagnetic force is applied to enable collective maneuver and how to provide a better performance and broader applications for such swarm highlight an important issue. Considering the trajectory planning problem of satellite swarm using inter-satellite electromagnetic force, a behavior-based collective planning scheme is developed by designing the desired velocity of each satellite as the sum of several different behavioral contributions, which are used to represent the internal and external interactions of the swarm. Therefore, the desired configuration is associated with the equilibrium points of the pre-designed kinematical field. Furthermore, the trajectory planning problem could be translated to a parameter optimization problem considering the swarm dynamics with inter-satellite electromagnetic force. Then based on the analysis of the applicability and advantages triggered by integrating the inter-satellite electromagnetic force into such behavior-based planning scheme, the collective trajectory planning problem with sole electromagnetic force actuation and hybrid actuation with thruster are studied respectively. Numerical simulations are carried out to verify the validity of the proposed algorithm, and the satellite swarm performance enhanced by inter-satellite electromagnetic force is discussed at last.