机载液压系统的主要发展趋势

对飞机特别是军用飞机机载液压系统的主要发展趋势进行了综述,并对国内外的机载液压系统的研究工作进行了一定的介绍,重量轻、体积小、高压化、大功率、变压力等是机载液压系统的主要发展趋势,尤其是高压变压力泵源系统对未来飞机的发展尤为重要。     

金城南京机电液压工程研究中心

中航工业金城南京机电液压工程研究中心(简称"中心")是我国航空机载机电系统产品的科研和生产基地,也是中国航空工业集团公司航空机电液压工程专业技术的研发中心,具有完整的预先研究、型号研制、设计制造、试验交付和维修服务的能力。中心属于国家重点扶持的中航工业机载5大中心之一,主要从事飞机机载机电综合控制系统的研究,其专业研究领域涵盖:飞机机电控制系统、飞机液压操纵系统、飞机环境控制系统、飞机燃油系统、飞机第二动力系统与飞机电源传动系     

机载液压系统故障诊断与健康管理

机载液压系统是关系飞机安全的重要功能系统,为提高飞机可靠性、安全性、经济性水平,现代先进飞机普遍采用故障诊断、预测与健康管理.本文研究总结了机载液压系统故障诊断与健康管理的历史发展,探讨了其关键技术,以期指导机载液压故障诊断与健康管理的研究和应用.     

基于Stateflow的民机液压控制逻辑仿真与验证

控制逻辑是机载系统的重要组成之一,对其进行仿真与验证有利于在飞机设计早期发现问题,从而提高系统的安全性。应用Matlab/Stateflow软件平台对民机液压控制逻辑进行了建模,通过控制信号设置和状态转移图的建立仿真实现了液压系统状态监控,泵源附件控制以及指示告警功能。结合液压控制面板的人机交互设计对逻辑模型进行了动态虚拟演示,提高了系统仿真的逼真度,验证了控制逻辑的有效性和准确性。     

基于GSPN的机载液压作动系统可靠性模型

机载液压系统具有余度降级、故障检测、隔离等动态时序过程,传统基于两元可靠性模型很难描述其动态行为和性能降级过程.针对这一问题,采用分层聚类和广义随机Petri网相结合建立了机载液压系统可靠性模型.利用该模型,详细分析了故障检测装置的故障检测率对系统可靠性的影响.分析结果表明,由于故障检测装置故障检测率的影响,机载液压作...     

飞机机载维护系统的设计考虑

飞机机载维护系统的主要目标是支持客户要求的飞机检修,以达到最小的维修成本和操作成本,达到最大的操作可靠性,因此在飞机设计中需要考虑如何设计机载维护系统。从机载维护系统的设计理念、系统安全与维护、飞机机载维护系统(OMS)故障处理、系统接口、维护处理、人机接口进行了探讨,希望能让读者更好地了解飞机机载维护系统,扩展设计思路,设计更好的机载维护系统。     

中航工业南京机电

南京机电简介中航工业南京机电是我国航空机载机电系统产品的科研和生产基地,也是中国航空工业集团公司机载机电专业的研发中心,具有完整的预先研究、型号研制、设计制造、试验交付和维修服务的能力。现有职工3000余人,其中研究员78人,高级专业技术人员近400人,其他专业技术人员近800人。南京机电的业务范围:航空机电综合管理系统、液压系统、燃油系统、空气管理系统和辅助动力系统等分系统的研发牵头和总成单位,带领相关单位开展技术研究与方案论证、产品研发制造及服务等工作,为客户提供系统解决方案;民机液压、燃油和空气管理系统的国际合作、转包生产和自主研发基地。     

某机载设备常闭式液压制动器的结构改进

按照某机载设备对液压制动器使用条件的特殊要求,对常用的常闭式液压制动器进行了结构改进。降低了液压制动器的工作噪音,在其结构基础上增加手动刹车和松刹车功能,设计手动操作接口,增加就位指示功能和接油装置,根据工作扭矩范围,计算得出弹簧的具体参数,使改进的液压制动器满足了在某机载条件下的使用要求。通过试验验证和工程应用,证明改进的液压制动器可以在某机载等特定环境下使用。     

电机泵系统动态性能仿真与分析

一体化电机泵是机载液压系统的发展方向之一.简要介绍了电机泵的产生背景及工作原理,利用AMESim搭建了电机泵系统的模型,并对额定运行及突然掉电时电机泵的动态特性进行了仿真和分析.仿真结果可为电机泵控制器的设计提供一定的参考.     

航空电子专辑

过去,国内习惯把飞机上除了发动机以外的系统称作“机载”,这实际上是一个不准确的表述。机载系统分为两类．一类是机电系统．如液压、燃油、电源．起落架、环控、防冰除冰等．这些系统与飞机是一体的．如果没有这些系统．飞机便不能升空．因此这类系统又称为平台系统或飞机系统．     

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.