基于等 Weber 数的结冰外形修正

由于设备条件的限制,在进行结冰风洞试验时,试验 Weber 数与目标 Weber 数往往存在差异,为了获得与目标 Weber 数对应的冰形,需要对试验结果进行修正。本文分析了进行 Weber 数修正的原因,提出了根据几何特征量进行结冰外形修正的方法,并以某超临界翼型为对象,对不同 Weber 条件下的结冰外形进行了仿真,研究了Weber 数变化对结冰的影响规律,在此基础上开展了基于等 Weber 数的结冰外形修正。研究发现：(1)Weber 数主要影响冰角特征,对水滴收集特性、结冰极限及驻点冰厚度影响较小;(2)存在一个敏感 Weber 数,低于敏感值时, Weber 数变化对结冰影响不大,当 Weber 数高于敏感值时,Weber 数变化对结冰有明显影响;(3)采用本文提出的冰形修正方法,能保证冰形的宏观轮廓与目标冰形一致,修正后的冰形能适量消除由于 Weber 数误差导致的冰形差异,提高试验的精度。     

Dynamic modeling and analysis of vortex filament motion using a novel curve-fitting method

Applications of a novel curve-fitting technique are presented to efficiently predict the motion of the vortex filament, which is trailed from a rigid body such as wings and rotors. The governing equations of the motion, when a Lagrangian approach with the present curve-fitting method is applied, can be transformed into an easily solvable form of the system of nonlinear ordinary differential equations. The applicability of Be′zier curves, B-spline, and Lagrange interpolating polynomials is investigated. Local Lagrange interpolating polynomials with a shift operator are proposed as the best selection for applications, since it provides superior system characteristics with minimum computing time, compared to other methods. In addition, the Gauss quadrature formula with local refinement strategy has been developed for an accurate prediction of the induced velocity computed with the line integration of the Biot–Savart law. Rotary-wing problems including a vortex ring problem are analyzed to show the efficiency, accuracy, and flexibility in the applications of the proposed method.     

大型飞机迎角保护控制律设计及试飞技术研究

针对大型飞机迎角保护控制律设计及试飞问题,通过杆位移-过载梯度的实时精确调整及取大值逻辑指令切换,设计了迎角保护控制律,实现拉杆到底飞机迎角达到且不超过限制迎角的目的。根据迎角保护控制律的功能及试飞目的,将整个试飞过程分为三个阶段,研究了各个阶段的试飞技术。仿真结果表明,所设计的控制律能够实现迎角保护功能,具有良好的控制效果。     

三维自适应终端滑模协同制导律

针对多枚导弹协同作战的问题,且多枚导弹之间保持有向拓扑通信的条件下,基于终端滑模法设计了视线方向及视线法向的双层协同制导律。其中,视线方向的制导指令能够保证导弹同时完成拦截任务;视线法向上的三维制导律能够保证每枚导弹以期望的视线角攻击目标,从而发挥各枚导弹的最大杀伤力,并且视线角的约束相当于规划了末制导段导弹的弹道问题,在一定程度上避免攻击目标前导弹间发生碰撞。同时,针对所设计的滑模制导律设计了新的自适应律,从而加快了滑模面的收敛速度并且削弱了由符号函数引起的系统抖振现象。基于李雅普诺夫稳定性理论,证明了所设计制导律的正确性,并在最后给出了数学仿真实验,验证了所设计制导律的有效性及优越性。     

Optimization and verification of free flight separation similarity law in high-speed wind tunnel

Based on the similarity of separation time, a similarity law optimization method for high-speed weapon delivery test is derived. The typical separation state under wind load is simulated by the numerical method. The real separation data of aircraft, separation data of previous test methods, separation data of ideal wind tunnel test of previous methods, and simulation data of the proposed optimization method are obtained. A comparison of the data shows that the method proposed can improve the performance of tracking. Similarity law optimization starts with the development of motion equations and dynamic equations in the windless state to address the problems of mismatching between vertical and horizontal displacement, and to address the problems of separation trajectory distortion caused by insufficient gravity acceleration of the scaling model of existing light model. The ejection velocity of the model is taken as a factor/vector, and is adjusted reasonably to compensate the linear displacement insufficiency caused by the insufficient vertical acceleration of the light model method, so as to ensure the matching of the vertical and horizontal displacement of the projectile, and to improve the consistency between the test results of high-speed projection and the actual separation trajectory. The optimized similarity law is applicable to many existing free-throwing modes of high-speed wind tunnels. The optimized similarity law is not affected by the ejection velocity and hanging mode of the projectile. The optimized similarity law is suitable not only for the launching of the buried ammunition compartment and external stores, but also for the test design of projectile launching and gravity separation.     

基于分数阶微积分理论的最优导引律设计

随着技术的发展及战场环境的日益复杂化,拦截机动目标的需求越来越大。然而传统制导律在拦截机动目标时存在制导精度差、末端过载突变的问题,故提出了一种基于分数阶微积分理论的最优导引律。首先,介绍了分数阶微积分的定义、性质及其数字实现方法;然后,分析了弹目相对运动关系,通过分数阶变阶次建模和最优控制理论推导出了分数阶导引律;最后,仿真结果表明：与传统比例导引法相比,所设计的分数阶最优导引律能够保持比例导引法良好的追踪性能且拦截时间能够缩短2s,末端过载值趋近于0。该方法解决了传统比例导引法在末端由视线角速率发散而导致的末端过载突变问题。     

三脉冲冷原子陀螺仪中基于内态演化的拉曼光光强补偿算法

由于在复杂环境中拉曼光功率不稳定会导致原子脉冲的宽度发生改变,从而影响陀螺仪的测量精度.通过对冷原子干涉仪的干涉全过程进行建模,计算得出了陀螺仪在拉曼光改变情形下输出相位的解析表达式,即建立了拉曼光在非近共振条件下强度变化时陀螺仪的输出值与外界载体运动之间的关系.与此同时,基于该解析表达式提出了一种对拉曼光光强的补偿算...     

多约束条件下的制导律研究综述

随着导弹等制导武器机动能力的增强,制导精度的提高,多约束条件下的制导律研究成为精确制导研究的新热点。简要介绍了多约束条件下的制导问题,重点评述了近年来多约束条件下的制导律研究情况,对目前多约束条件下的制导律设计进行了比较详细的研究,系统分析了各种方法的优缺点,并分析了其可能的研究内容动态和方向,为精确制导技术的发展提供了参考和借鉴。     

飞行控制系统设计方法现状与发展

飞行控制系统设计是飞机设计的一项重要内容,它的先进性很大程度上决定了飞机的先进性。首先,概述了飞行控制系统及控制律的设计过程;然后,对国外先进飞机控制律设计现状进行评述。飞行控制律的设计存在两类主要的方法:经典设计方法和多种先进控制方法。着重论述了目前国内外在飞行控制系统设计中重点研究和发展的几种方法,包括最优控制、动态逆控制、鲁棒控制和智能控制等的基本原理、应用现状和工程实现问题,并指出多种方法综合控制是控制律设计的发展方向。     

Ti6Al4V合金冷拔过程变形机制研究

研究了钛合金经冷拉后的变形组织和性能,金相、透镜观察表明,位错滑移是钛合金室温下塑性变形的主导机制.钛合金经过冷拉拔后的组织性能变化可分为3个阶段:第一阶段为快速硬化阶段,以大晶粒的变形为主,位错缠结形成;第二阶段其抗拉强度值增加趋于平缓,近乎于一个平台,部分小晶粒也开始参与变形,位错带形成;第三阶段为应变量大于0.6...