某型飞机液压油箱漏油故障分析

某型飞机液压油箱在外场使用中出现油液渗漏现象,通过对故障现象确认、机理分析、故障验证,找到了故障根源,提出改进措施,在实际应用中具有借鉴和指导意义。     

一种民用飞机液压系统自增压油箱容积计算方法

选择合适的油箱容积是保障液压系统正常工作的必要前提，为了能够合理计算民用飞机自增压油箱的容积，基于SAE AS5586 飞机液压系统油箱通用设计要求，介绍并分析飞机液压系统工作中作动筒、蓄压器以及油液物理特性等所产生的变化容积的计算方法，提出一套循序渐进的油箱容积计算方法以求得油箱设计所需的各类容积值；以某型飞机液压系统油箱容积计算为例，通过对极冷极热天气条件下各飞行阶段的油量分析，并和机上油箱油量记录曲线对比，验证提出的容积计算方法的有效性。结果表明：该型飞机液压系统油箱容积在全飞行阶段均能满足要求，本文所提油箱容积计算方法可行，可用于类似液压系统油箱容积计算。     

“新舟”60飞机压力加油系统故障分析及改进措施

较早批次的"新舟"60飞机在进行3C检(大修)后多次出现I组油箱无法压力加油的故障,结合该型飞机压力加油系统及其部件原理,分析了该型飞机I组油箱无法压力加油的故障原因并提出改进措施,提高了飞机压力加油系统的可靠性。     

浅谈某型飞机供油箱超压的排故方法

针对某型飞机空中报供油箱超压的故障现象,分析故障产生的引发因素,再结合实际经验和引发因素梳理排故思路,并通过飞参数据判读和该型飞机燃油系统的输油原理进行具体分析,针对可能性最大的故障因素实施有针对性的排故方案,并结合分析结果进行故障验证,最终确定了导致故障的真正原因,排除了故障,并总结了相关的经验。     

某型飞机交流电动泵工作异常分析

以一起某型飞机4号油箱内交流电动泵工作异常典型故障为例,研究分析了4号油箱内交流电动泵工作异常的主要原因以及发生同类故障的模式,可为燃油控制系统的排故提供参考。     

某型飞机液压系统功率转换装置结合面渗油故障分析

通过对某型飞机液压系统试验过程中出现的功率转换装置渗油故障进行分析,结合产品的工作原理和故障现象,查找和定位故障原因,对该功率转换装置产品提出改进优化措施,保证后续产品的质量。     

某型飞机发动机舱供压导管漏油故障分析

某型飞机试车过程中发动机舱液压系统供压管路接头连接处发生漏油故障,严重影响了试车安全,此故障的排除需要拆卸发动机。通过对液压系统原理进行分析,找到了故障原因,并对液压系统的试验方法进行了针对性改进,消除了故障隐患。     

某型飞机双向液压锁故障研究

针对某型飞机地面试车时襟翼下掉不能正常收放故障现象进行了排查和分析,在分解双向液压锁后检查发现故障原因是YYS7-105螺母断裂,进一步分析确定了螺母断裂的原因,制定了相应的改进措施,避免了该型飞机类似故障的再次出现。     

某型飞机起落架收放液压系统故障分析及排除

针对某型飞机在起落架收放过程中遇到的一个液压系统故障问题,通过故障定位、故障机理分析、流量及流阻试验、理论计算分析产生故障的原因,并据此设计了改善操作规范、控制椎体安装的钢球突出量、调换应急排油活门进油口与回油口等针对性的解决方案,完善了此型飞机设计上的缺陷,提升了飞机液压系统的可靠性。     

机动过程中飞机通气系统性能计算研究

 燃油箱通气性能计算是通气系统设计过程中的一个重要环节。对某型飞机的通气系统进行了分析,在网络算法和时间微分法的基础上,研究了通气系统供油油箱组和非供油油箱组内空气压力的计算模型,并给出了飞机机动过程中油箱组通气的模拟方法。针对某型飞机油箱通气系统,模拟了某一特定机动过程下,各油箱组内空气压力的变化过程,计算结果用于该机通气系统性能的验证,效果良好。     

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.