New model-based method for aero-engine turbine blade tip clearance measurement

Active control of aero-engine turbine tip clearance is one of the best chances for engine performance uplift currently. To do that, the first requirement is real-time measurement of tip clearance in aero-engine working environment. However, turbine complexity makes it unlikely for tip clearance sensors to be loaded. In recognition of that, this paper proposed a model-based method for tip clearance measurement. Firstly, by considering previously wrongly neglected factors such as load deformation, a mathematical model to monitor dynamic tip clearance changes is built to improve calculation accuracy. Then, after clarifying the coupling relationship between engine models and tip clearance models, this paper builds a component-level mathematical model integrating dynamic characteristics of turbine tip clearance, which helps realize accurate measurement of tip clearance in working environment. How tip clearance affects turbine efficiency is studied afterwards and reported to aero-engine model, so as to mitigate performance difference between aero-engine model and real engines caused by turbine tip clearance. Lastly, by hardware-in-the-loop simulation, tip clearance model demonstrates 15.9% better accuracy than previously built models in terms of turbine centrifugal deformation calculation. As tip clearance measurement model takes averagely 0.34 ms in calculation, meeting the operation requirement, it proves to be an effective new way.     

φ50毫米微波测速系统

本文叙述了在50毫米二级轻气炮发射管内采用的微波反射技术:当模型运动的时候,将射入炮管内的微波和从模型上反射的微波间的相位变化记录下来,便可以获得炮管中模型运动速度的连续测量。     

缝隙耦合HT对特性的分析

分析了通过窄缝隙耦俣的矩形波导Ｈ面Ｔ形接头对（以下简称ＨＴ对）的电气特性，利用等效原理和切向场连续性建立积分方程组，采用矩量法化积分方程为代数方程进行数值求解，获得散射场和等效散射参数，以Ｘ波段标准矩形波导ＨＴ接头对为例进行具体求解和计算，以及实验验证，得到良好结果。     

基于贝叶斯网络和共因失效的飞机电源系统可靠性分析

飞机电源系统中的冗余设计提升了飞机系统的可靠性，但同时也增加了共因失效发生的概率。为了准确分析飞机电源系统的可靠性，首先，采取α因子模型对共因失效部件的失效率进行分解计算，并利用贝叶斯网络（BN）建立考虑共因失效的飞机电源系统可靠性模型。然后，对比分析考虑与不考虑冗余部件之间的共因失效因素时飞机电源系统及其子系统的可靠性。结果表明，考虑冗余部件之间的共因失效因素时，得到的飞机电源系统及其子系统可靠度相对于不考虑冗余部件之间的共因失效因素时较低，更加吻合实际情况。     

大型复杂构件制造过程残余应力演化与调控

归纳了残余应力的基本类型及各类残余应力的计算机仿真方法，概述了残余应力形成与演化行为及残余应力调控技术的研究现状。以机械臂基座本体淬火过程为例，展示了有限元仿真在大型复杂构件残余应力演化行为分析上的应用；以工字型材模压去应力为例，通过有限元仿真重现了变截面构件模压去应力的过程并分析了模压去应力的影响因素。讨论了残余应力仿真预测与调控技术应用于组件及其涵盖构件制造-服役全寿命周期的可行性，预测了其集成于智能制造技术体系的巨大潜力。     

扫描波束缝隙阵列天线方案设想

扫描波束缝隙阵列天线是一种相控阵天线,采用寄生振子实现波导缝隙天线的圆极化辐射,全金属结构可以承受恶劣的温度环境。每副天线可实现±45°一维扫描,两副天线组阵再辅以卫星自旋,可以实现全空间覆盖。此天线的优点是扫描范围宽、重量轻、结构紧凑和能在极端温度下工作。文章介绍了该天线的技术特点、方案设计和仿真分析结果。     

航天器用高性能塑封器件的板级鉴定方法

由于技术进步和设计需要,航天应用中不可避免地会遇到选用低质量等级塑封器件的情况。随着器件功能的日益复杂和封装的多样化,实现器件级的鉴定越来越困难。文章提出了基于板级系统对塑封器件进行鉴定的方法,包括几个标准的评估方面,如器件级筛选、破坏性物理分析、特殊的设计评估等;并介绍了一种基于局部加热技术,能够考核器件热温度特性的板级评估方法。     

巡航导弹可折叠弹翼支架中驱动装置工作状态的分析与研究

根据巡航导弹可折叠弹翼支架中驱动装置的工作条件,分析了不同安装形式的受力状态,指出现有机构的不足之处,提出了新的设计方案和实施新方案的具体措施,并对新方案中驱动装置的行程变化状况和动力特性进行了较为详细的分析。     

Interaction of oblique wave beam with ionospheric layer F2

Interaction of a powerful obliquely incident wave beam of decameter radio waves with the ionospheric F2 layer is analyzed. Much like the linear case, propagation through the natural anti-waveguide layer F2 splits the initial beam. Some part of its energy leaks through the ionospheric layer, the other part goes back along a downward trajectory. However, nonlinearity leads to further stratification of the ionospheric layer. A new feature, in comparison with the linear case, is appearing a narrow waveguide beneath the F2 layer maximum which traps a small part of the beam energy. We study the relationship between these parts of the wave field in a simplified model of parabolic F2 layer, with nonlinearity caused by thermal plasma expulsion from the high field intensity region. Analytical results are supplemented with numerical estimates of the effects.     

波音737CL飞机模拟式座舱压力控制系统部件预防性维修与控制

针对波音737CL飞机模拟式座舱压力控制系统部件老龄化问题,提出部件预防性维修措施．减少因部件内部元器件老化造成的重复性故障,供业内同行参考。