航电产品内部的三防涂料及涂覆处理

航电产品不同于一般的地面电子设备,具有很高的绝缘性和可靠性要求,目前航空行业内对其产品外部的三防(防湿热、防盐雾、防霉菌)处理研究较多,形成了比较完善的材料、工艺标准体系[1-2].但是对航电产品内部(内表面和印制电路板组装件)的防护研究较少,且一般大多偏重于印制电路板组装件(Printed Circuit Board Assemby,PCA),对内表面的防护不够重视,经常是各个PCA单元防护很好,但整机在试验或使用过程中却频繁出现故障.因此,加强航电产品内部的三防涂料及涂覆处理研究,对提高航电产品的可靠性具有十分重要的意义.但常用涂料都存在一些缺点,针对存在问题,我们研发了一种新的三防涂料.     

应用应变测试的航电产品组装工艺优化研究

新一代航电产品的印制板组件互连密度高,微小封装片式器件及高密度细间距芯片大量应用,在产 品组装过程中印制板受到机械应力翘曲而引起器件焊点失效成为痛点问题。本文提出应用应变测试识别组装工 艺风险点,针对性采取工艺优化措施,并采用应变测试量化验证优化效果。试验结果表明,提出的方法能够有 效量化工艺风险,并将组装过程中的产品应变数值降为原来的三分之一,满足了IPC 9704A 标准的要求。     

整机、印制板喷涂SO1—3聚胺基甲酸脂清漆工艺

采用ＳＯ1— 3聚胺基甲酸脂清漆、多沾性羟基聚酯和异氰酸甲苯的合成物组成的喷涂材料 ,具有光泽丰满、坚硬耐磨、耐水、耐碱等优点 ,用它喷涂整机和印制板 ,可以提高整机与印制板防潮、防霉、防盐雾的性能 ,从而提高仪器的寿命和可靠性。地面仪器和印制板采用ＳＯ1— 3清漆喷涂工艺方法 ,经过火箭多次飞行和综合试验的考验证明 ,均达到三防的要求 ,可算目前国内先进的三防处理工艺 ,有推广应用价值 ,效益也很显著。整机、印制板喷涂SO1—3聚胺基甲酸脂清漆工艺     

舰载航电产品结构件腐蚀防护设计

舰载航空电子产品腐蚀防护是一个系统设计工程,包括机箱结构设计、金属材料选型及表面涂层设计三个主要方面。对航电产品机箱外表面腐蚀防护设计最重要的三个方面进行了分类讨论,以提高航电产品机箱整体防护性能,并对影响外表面腐蚀重要环节的外表面防护失效机理进行了初步讨论。     

印制板的试验模态分析技术研究

介绍了某航电设备的印制板应用锤击法进行试验模态分析的试验流程,计算了其前9阶模态参数(固有频率、阻尼系数等)和前4阶振型.对试验结果的有效性进行了分析,其分析结果可为印制板结构设计及修改提供参考.     

基于相关分析的航空透明件弹性常数超声测定

航空透明件属于关键部件,主要包括飞机风挡、座舱盖和窗玻璃等,要求有足够的结构强度和长的使用寿命。由于现代飞机性能不断提高,对透明材料的性能也提出更高要求。材料常数的测定对于研究新材料、合理使用现有的材料、改善材料性能、检测缺陷与应力状态以及预估其使用...     

我国适航规定轻型水陆两栖飞机部分的修订建议

本文从水陆两栖飞机的国内外发展现状入手,展望了水陆两栖飞机的未来应用。结合我国目前的适航审定规则与国外发达通航国家的适航规章,从飞行性能和特征、结构和载荷、航电系统三个方面比较分析了现有适航规定中水陆两栖飞机的适航要求异同,总结其特点,并分析了适航规章的不足；根据轻型水陆两栖飞机的实际结构特点和任务模式,提出了我国现有适航规定在水陆两栖飞机方面的适航要求在起飞特性、结构安全、密封和腐蚀防护以及驾驶舱系统集成等方面的增补建议。     

复杂环境下起落架舱电缆组件设计与探讨

基于复杂环境下的电缆组件防护设计问题,以某型飞机为例,从电缆组件的组合防护、电性能防护、力学特性防护、分叉处的防护、电磁兼容防护、外部防护、与插头等部件连接处的防护等方面给出了复杂环境下的起落架舱电气线路互联系系统(EWIS)电缆组件防护设计方法,该方法已通过某型飞机装机使用和验证,证明能够满足电缆组件设计的腐蚀防护、电磁防护、防水密封、机械防护、适航等要求,并可以提高飞机电缆组件所控制系统的安全性和可靠性。     

直升机旋翼桨叶防/除冰技术新思路

为了满足直升机全天候飞行和特殊环境中飞行的要求,有必要对直升机的旋翼桨叶、发动机进气道、风挡玻璃等部位采取防/除冰防护。常用的电热等防/除冰方法存在各种弊端,如消耗大量电能、冰防护装置复杂、脱冰产生危害等,而超疏水表面材料以零耗能、零设备、零操作的特点在防/除冰方面具有巨大的应用潜力。本文在总结现有防/除冰方法及其特点的基础上,介绍了超疏水表面材料的最新研究进展,探讨了其在直升机防/除冰技术上应用的可能性,为解决直升机的防/除冰问题提供了一个新思路。     

先进综合航空电子技术的特征分析

几十年来,航空电子系统的结构经历了从分离到联合、从综合到先进综合的发展历程。本文就先进综合航空电子系统的主要特征进行了分析,包括开放性系统结构、系统总线的统一网络化、组件的标准模块化、商用货架产品以及航电系统软件的使用等。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.