通用飞机发动机一体化试验平台的设计与应用北大核心

为测量发动机装机后的推力等性能指标,设计了一个通用飞机发动机一体化试验平台。该平台采用可调式品字布局,能有效兼容不同类型飞机推力测量试验需求。测控系统采用网络式多数据源融合测试结构,可通过多种方式同步测量多台发动机性能数据和推力数据。使用该试验平台对大型运输机发动机的装机推力进行了直接测量,结果表明:试验平台各系统工作良好,测试精度满足飞机推力测量技术要求。     

通用飞机发动机一体化试验平台的设计与应用

为测量发动机装机后的推力等性能指标,设计了一个通用飞机发动机一体化试验平台。该平台采用可调式品字布局,能有效兼容不同类型飞机推力测量试验需求。测控系统采用网络式多数据源融合测试结构,可通过多种方式同步测量多台发动机性能数据和推力数据。使用该试验平台对大型运输机发动机的装机推力进行了直接测量,结果表明:试验平台各系统工作良好,测试精度满足飞机推力测量技术要求。     

滚珠式操纵软轴技术研究

<正>在非电控飞机上,一般是采用连杆、推拉钢索或者滚珠式操纵软轴来操纵发动机主泵调节器,控制发动机各个工作状态。飞机(主要指军用飞机)向高性能方向发展对主泵调节器的机载操纵系统提出了小空间、低重量、易安装、高可靠性的要求。以往飞机采用的连杆、推拉钢索由于占用飞机空间大、安装复杂、可靠性不高等原因已不能满足飞机的发展要求,为此提出了能够满足这一要求的滚     

飞机和发动机控制一体化设计方法标准研究

针对国内飞机与发动机控制一体化设计标准全面展开研究工作,围绕飞机、发动机控制架构和使用分析、系统功能、性能需求设计分析、系统工作环境、与飞机/发动机接口关系设计分析、系统可靠性、维修性、保障性、安全性、测试性要求设计分析等提出了标准编制的内容要求,并对标准验证中试验验证要求提出建议,未来为标准制定提供技术支撑和借鉴。     

基于飞机发电机测试的电负载控制系统

针对某型发电机性能测试需要,采用现代计算机控制技术设计开发了电负载控制系统.根据飞机供电系统性能参数要求和实际设备,采用高速数据采集卡采集发电机电网参数并计算功率.由可编程控制器控制电负载单元,测试特定负载下发电机性能及其对发动机影响.运用多线程技术,提高了系统实时性.经验证,系统满足实际测试要求,运行稳定可靠,测量准...     

遄达900发动机的发展,设计特点

一、发展背景1996年，波音公司与空中客车工业公司先后提出研制下一代、将于2000年后投入营运的大型四发客机即B747－500X／600X，A3XX的发展计划。这些飞机所需的发动机，要求推力范围比用于B747－400的高，比用于B777的要低，且耗油率要低，以便降低直接使用成本10％左右。目前，尚无能满足这些飞机所要求的发动机。为此，罗·罗公司推出了遗达900发动机，来满足这些飞机的要求，它是在通达800的基础上衍生发展的，与此同时，GE公司与PW公司各按50％的投资比例组成GE／PW发动机联合公司，并推出了GP7176发动机，这是一种全新设—…     

飞机外部噪声预计系统在适航测试中的应用

为满足飞机适航噪声验证试验的需求,根据CCAR-36部中有关飞机适航噪声测试规定,归纳了适航噪声测试的根本目的,采用飞机外部噪声预计系统（AEPN）对某型号飞机发动机进行了外场噪声预计和分析,提出等效航迹和确定地面测试区域的工程方法,解决了如何准确和完整记录最大噪声10分贝降区域这一关键的适航噪声测试试验问题。     

作战飞机动力装置气动力优化

以优化作战飞机动力装置的气动力设计为中心，首先分析了作战飞机动力装置的气动力要求以及目前在设计中存在的一些问题，详细论述了进气系统与排气系统的优化设计方法。随着发动机技术的进展和飞机的作战使用要求的不断提高，发动机进气和排气系统的设计变得越来越复杂，不但要适应飞机的飞行速度和高度的变化，还要能够满足飞机的隐身性要求，利用CFD技术可以开发先进的分析方法，分析复杂的流场，从气动力方面优化飞机的进气系统和排气系统。     

航空发动机参数显示技术发展趋势

介绍了目前国内航空发动机参数显示技术的现状及其发展过程，通过分析，阐述了为满足今后使用及飞机座舱显示仪表电子化、综合化的发展要求，应尽快研制并形成相对独立的航空发动机参数综合显示系统。详细叙述了航空发动机参数综合显示系统的基本要求及组成。     

飞机／推进系统一体化设计

飞机 /推进系统的一体化设计是从整个飞机系统出发来进行机体、发动机的研究设计。这一设计方法要求根据具体飞机的设计要求 ,从整体出发 ,在综合考虑飞机、发动机等性能的基础上 ,优选出飞机 /发动机的设计方案 ,使得飞机的性能最优。对飞机 /推进系统一体化设计的概念、程序和研究内容 ,以及如何获得最佳匹配进行了介绍 ,给出了实例。     

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.