基于飞机油箱模型形状特征油量测量切片步长选择方法研究

 在分析飞机数字式油量测量过程中目前广泛使用的切片法油量测量原理的基础上,针对现有的定步长切片法无法得到准确、可靠的燃油质量特性数据库的缺陷,结合对飞机油箱模型形状特征的分析,提出了基于飞机油箱模型形状特征的油量测量切片步长选择方法。此方法包括切片步长整体和局部选择两个过程,整体选择以实现相邻两切片平面所夹油箱模型体积近似相等为目的来确定切片步长,以体现油箱模型截面整体变化规律;局部选择以设计切片平面与截面突变平面重合或尽可能接近的方式,突出油箱截面的局部变化特征。实验结果表明：该切片步长选择方法较定步长方法能够建立更为合理、可靠的燃油质量特性数据库,从而提高了油量测量精度。     

二维翼段颤振的μ控制

 采用超声电机作为作动器来实现含控制面的翼段颤振鲁棒抑制。针对作者设计的二维翼段颤振主动抑制系统，通过理论与实验相结合的方法，建立了考虑沉浮方向阻尼和作动器模型参数不确定性的控制系统模型，设计了μ控制器，并对控制器做了降阶处理。数值仿真和风洞试验表明，μ控制器可有效地抑制颤振的发生，将颤振临界速度提高23.4%。相对于H_∞控制器，μ控制器的控制效果和鲁棒性更好。     

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.      

Abnormal Shape Mould Winding

为解决网格化芯模的缠绕问题,本文提出了复合材料面片缠绕机理;接着详细分析了面片缠绕过程中的芯模凹曲面上纤维滑线和架空现象,应用微分几何曲面理论和空间几何理论,提出判据及其解决方案;最后,针对飞机发动机进气道的缠绕成型,编制缠绕控制程序并进行相应的实验,验证了面片缠绕方法的可行性。     

基于H∞性能指标的质量矩拦截弹鲁棒控制

 以所建立的质量矩拦截弹数学模型为基础，利用微分几何的反馈线性化理论，得到一个解耦线性系统，考虑到拦截弹的鲁棒性要求和3个滑块的协调控制问题，提出采用双回路的设计方法，内回路采用线性二次调节器（LQR），外回路采用考虑混合灵敏度问题的H_∞控制设计。仿真结果证明了该方法动态性能满足设计要求，同时对系统参数的不确定性具有较强的鲁棒性。     

航天器返回地球的气动特性综述

航天器返回地球的飞行过程中,气动特性是实现将宇宙飞行速度减到落地前速度、保证再入飞行得到有效控制以及再入防热安全可靠的关键因素。针对简单旋成体气动外形、半弹道式再入控制、烧蚀防热类返回航天器,综述了返回地球过程中变化的空气流域特性、航天器周围的气体绕流环境、空气与航天器作用产生的动力学与热效应等。系统地给出了该类航天器的再入气动特性参数与飞行性能的共性规律,包括:气动阻力与再入减速、气动升力与再入轨迹控制、配平攻角与飞行稳定性、气动加热与防热,以及再入过程中不同气动特性航天器、气象条件变化等对再入飞行性能的影响规律。为航天器开展返回飞行过程的跨流域气动性能工程研制提供设计参考。     

基于马赫数分布可控曲面外/内锥形基准流场的前体/进气道一体化设计

提出了一种高超声速飞行器乘波前体的外锥形基准流场设计方法,在锥面马赫数分布规律给定的条件下,通过有旋特征线法实现反设计,提高了基准流场设计的灵活性。该基准流场通过锥形"下凹"弯曲激波和波后等熵压缩波系压缩气流,可以在较短的长度内完成高效压缩。基于反正切马赫数分布外锥形基准流场设计的乘波前体具有较高的容积率,乘波特性良好且出口均匀,设计点时有黏升阻比为1.89。另外,基于该乘波前体和马赫数分布可控的内收缩进气道给出了一种双乘波的前体与进气道一体化设计方案,实现了内外流分别独立乘波,充分发挥了乘波前体和内收缩进气道的各自优势。     

Potentials of manufacture and repair of nickel base turbine components used in aero engines and power plants by laser metal deposition and laser drilling

IntroductionExpensive turbine parts like HPT(HighPressure Turine)blades or vanes are replaced bynew parts in case of damage.For example theburn through of the inner side of a blade or vane(Figure 1)is a frequently appearing damage,which cannot be repaired…     

Enhancing the efectiveness of film cooling

Advanced gas turbine stages are designed to operate at increasingly higher inlet temperatures to increase thermal efficiency and specific power output.To maintain durability and reasonable life,film cooling is needed in addition to internal cooling,especially for the first stage.Film cooling lowers material temperature by forced convection inside film-cooling holes and by forming a layer of coolant about component surfaces to insulate them from the hot gases.Unfortunately,each cooling jet forms a pair of counter-rotating vortices that entrains hot gas and causes the film-cooling jet to lift off from the surface that it is intended to protect.This paper gives an overview of efforts to enhance the effectiveness of film-cooling.This paper also describes two new design concepts.One design concept seeks to minimize the entrainment of hot gases underneath of film-cooling jets by using flow-aligned blockers.The other design concept shifts the interaction between the approaching hot gas and the cooling jet to occur further above the surface by using an upstream ramp.For both design concepts,computational fluid dynamics results are presented to examine their usefulness in enhancing film-cooling effectiveness.      

Guide for Authors

<正>About Journal Chinese Journal of Aeronautics(CJA)is a comprehensive academic journal dealing with the fields of aeronautics and astronautics.It reports researches concerning the two fields in China and abroad to promote the academic exchange.Founded in 1988 and sponsored by the Chinese Society of Aeronautics and Astronautics and Beihang University,CJA publishes papers bimonthly,with issues released in February,April,June,August,October and December.     

Guide for Authors

<正>About Journal Chinese Journal of Aeronautics(CJA)is a comprehensive academic journal dealing with the fields of aeronautics and astronautics.It reports researches concerning the two fields in China and abroad to promote the academic exchange.     

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.     

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 ℃).     

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.     

跨流域高超声速绕流Boltzmann模型方程并行算法

通过对Boltzmann方程碰撞积分进行模型化处理,提出了统一描述各流域复杂高超声速流动输运现象的气体分子速度分布函数控制方程,使用离散速度坐标法对分布函数方程所依赖的速度空间离散降维,构造出直接求解分子速度分布函数的气体动理论耦合迭代数值格式,研制了复杂飞行器高超声速绕流气动热力学计算模型。基于对气体动理论数值计算方法内在并行性、变量依赖关系、数据通信与并行可扩展性的分析研究,使用区域分解并行化方法提出了新型的气体动理论数值算法并行方案;研究了数据的并行分布与并行执行特征,开展了大规模的并行化程序设计,构造了可稳定运行于成千上万CPU的高性能并行算法,用以模拟各流域复杂飞行器的高超声速绕流问题。以稀薄流到连续流环境下不同Knudsen数、不同马赫数的可重复使用类球锥卫星体及翼身组合复杂飞行器等气动力、热绕流问题为研究对象展开大规模并行计算,并进行算法验证,所得计算结果与理论分析、直接模拟蒙特卡罗方法(DSMC)的模拟值及有关实验数据吻合较好,揭示了飞行器跨流域高超声速下的复杂流动机理与变化规律,提供了一条能够可靠模拟高超声速飞行器跨流域气动力及热问题的统一的算法应用研究途径。     

一种鼻锥钝化高超声速轴对称进气道流动特性实验

前缘钝化尺度是高超声速进气道设计中的关键参数。针对一种前体锥加弯曲压缩面的高超声速轴对称进气道,选取最大尺度为3.2mm(5%唇缘半径)的几种典型鼻锥钝化半径,在马赫数Ma=6来流,及模型安装攻角为0°、4°、7°的条件下开展鼻锥钝化尺度对进气道流动性能影响的实验研究。采用纹影拍摄及压力测量记录各来流条件下进气道前体流场结构及壁面压强分布,并在无攻角来流条件下利用微型扰流器进行边界层强制转捩研究。结果表明,对无攻角来流而言,即使是尺度高达3.2mm的钝化半径对进气道前体流场结构及壁面静压分布也基本没有影响。此来流条件下,几种不同鼻锥钝化半径的前体压缩面均出现小范围流动分离,而添加扰流器后该分离区均消失。钝化尺度的影响随着攻角的增加而显现,尽管不同鼻锥钝化尺度下迎风面流场及壁面压强分布几乎没有差别,但背风面随钝化尺度增大表现为边界层明显增厚、流动趋于不稳定。其中最大钝化尺度R=3.2mm的构型在4°攻角来流时背风面即出现明显的分离区,而7°攻角来流时背风面更是出现大范围流动分离、进气道背风侧不起动,并导致进气道内部壁面压强显著下降。     

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。     

On Nonlinear Evolution of C-type Instability in Nonparallel Boundary Layers

The process of evolution, especially that of nonlinear evolution, of C-type instability of laminar-turbulent flow transition in nonparallel boundary layers are studied by means of a newly developed method called parabolic stability equations （PSE）. Initial conditions, which are very important for the nonlinear problem, are investigated by computing initial solution of the harmonic waves, modifying the mean-flow-distortion, and giving initial value of TS wave and its subharmonic waves at initial station by solving linear PSE. A numerical method with high-order accuracy are developed in the text, the key normalization conditions in the PSE are satisfied, and nonlinear PSE are solved efficiently and implemented stably by the spatial marching. It has been shown that the computed process of nonlinear evolution of C-type instability in Blasius boundary layer is in good agreement with the experimental results.     

Adaptive Sliding Control of Six-DOF Flight Simulator Motion Platform

本文使用Newton-Euler法推导了六自由度飞行模拟器运动平台完整的线性化形式的动力学方程,并以此为基础,提出了一种在任务空间中的非线性自适应滑模控制方法。这种控制方法将系统中的不确定性分为定常不确定参数和时变不确定参数,利用非线性自适应控制对定常不确定参数进行辨识,同时结合滑模控制对时变不确定参数和外部扰动进行补偿。通过数值仿真分析表明,该控制策略能准确识别运动平台的载荷、惯量、重心等参数,同时又能有效地提高系统的鲁棒性能。