空战仿真中机动控制模型研究

针对现代作战飞机方案评估和设计的要求,构建了现代空战仿真系统中计算机控制的飞机仿真基本框架。根据现代空战中典型机动动作对速度矢量的指向要求,从控制飞机速度矢量出发,建立了一类空战机动动作控制的基础模型,并对能反映飞机性能的限制环节进行了建模。仿真结果表明,利用该模型对飞机进行方案评估和性能指标设计是合理的,所建模型能够较好地仿真空战机动,体现飞机性能指标对空战机动的影响。     

飞机典型二次电源变换装置的建模方法研究

针对典型二次电源变换装置的自耦变压整流器(ATRU),分别采用基准建模和功能建模两种方法建立了仿真模型,对飞机电源系统正常和故障工况下进行了仿真分析及对比。结果显示,功能模型的仿真结果在功能、性能以及响应速度上更优于基准模型,因此,在工程上可以采用功能模型对电源系统进行仿真建模分析。     

飞机环控温控系统的半物理仿真及在机电综合管理技术研究中的应用

机载机电系统综合控制管理(简称公管系统)是机载机电设备发展的必然趋势,为了研究公管系统对机电子系统的控制、管理功能,需要对子系统进行建模仿真。本文针对某型飞机环控温度控制系统工作过程对环控温度控制系统关键附件进行了数学建模,同时针对某课题研究内容的需要,研究如何采用半物理仿真的方法对飞机环控温度控制系统进行系统建模和环境仿真并进行了系统仿真验证试验,最后给出结论。     

基于有限状态机的飞机供电系统控制器建模仿真

为验证飞机供电系统控制保护逻辑设计的合理性,建立了供电系统控制器类模型并进行了仿真。在对比控制器类不同建模方法的基础上,指出了基于有限状态机建立此类模型的方法适用于方案设计阶段对控制保护逻辑建模仿真,并以飞机发电机控制器为例进行了建模仿真。结果表明:模型符合设计要求,控制逻辑和时序逻辑正确,建模方法简洁快速。     

导叶伺服动力学系统通用建模方法

针对现有导叶伺服系统模型跨平台联合仿真速度慢、通用性差的问题，提出了一种基于动力学特性方程的、部件通用性 强的导叶伺服系统通用建模方法。采用部件建模法从底层方程到部件级模型，再到顶层系统，形成层次化、模块化的建模架构，使 原理与工程应用有机融合；通过对导叶伺服系统各组成部件进行工作机理分析，建立导叶伺服系统的AMESIM模型，推导各组成 部件的动力学特性方程，开发Simulink部件模型库；与AMESIM模型进行对比验证，构建Simulink导叶伺服动力学系统机理模型。 结果表明：系统模型稳态误差不大于0.12%，斜坡响应跟踪误差为3.7%，对于幅值为作动筒位移5%的不同频率正弦指令信号，导 叶伺服闭环系统带宽不小于8 Hz。该导叶伺服动力学系统模型具有较好的准确性、稳定性和动态特性，是可行和有效的，具有明 显的推广应用价值和跨平台多学科联合仿真优势。     

飞机综合保障建模分析

从系统学和系统工程的角度对飞机综合保障模型研究对象的分析描述。结合现代复杂系统建模技术。提出飞机综合保障建模总体思路和框架。通过建立装备体系的战备完好与持续能力评价体系。按飞机综合保障仿真模型进行仿真试验。仿真结果分析和模型修改优化．在现在武器装备信息系统基础上，进行改造和扩充．完成对作战单元的战备完好性、任务成功性和保障能力评价。进一步对联合作战的保障需求进行分析决策打下良好的基础。[编者按]     

基于Petri网的飞机复杂系统可靠性分析方法研究

Petri网在建模方面具有较强的可视性及良好的动态表达性,提出一种利用Petri网对飞机复杂系统进行可靠性建模的方法,并通过蒙特卡洛仿真方法对Petri网模型进行仿真求解,形成一套完整的可靠性分析理论;以某型机电传飞控系统为例进行建模计算,验证上述方法的可行性和精确性.结果表明:本文提出的基于Petri网的可靠性分析理论,能够有效应用于飞机复杂系统的可靠性分析.     

复合材料飞机动力学建模研究

在进行复合材料飞机气动弹性、动响应等分析时,需要进行飞机结构动力学建模.为此,基于经典层合板理论进行了复合材料刚度的等效计算,结合结构力学闭剖面理论分析了飞机剖面的弯曲、扭转刚度特性,并根据刚度分布建立了全复合材料飞机的动力学单梁模型.与地面共振试验结果的对比表明,复合材料飞机动力学单梁模型是有效的,且相对板壳模型更接近试验结果.建模方法对复合材料飞机结构设计具有指导意义.     

基于定部件效率的航空发动机通用性能仿真系统构建

根据飞机设计阶段对航空发动机性能仿真简便、快速和有效的要求,在基于定部件效率的航空发动机性能仿真方法基础上,对航空发动机部件进行通用性建模,并采用面向对象技术构建通用航空发动机性能仿真系统。采用定部件效率模型对航空发动机性能进行仿真,降低了航空发动机性能仿真过程的专业性要求;同时,采用面向对象技术建立通用的航空发动机性能仿真系统,提高了仿真代码的重用性及仿真系统的适用性。利用该仿真系统建立双转子混排涡扇发动机和自由涡轮式单转子涡轮螺旋桨发动机仿真对象模型,并对某型双转子混排涡扇发动机稳态特性进行仿真,验证了仿真系统的有效性。     

基于变摩擦系数的飞机刹车系统仿真研究

飞机刹车盘摩擦系数受到多种因素的影响和制约。为了研究刹车盘摩擦系数的变化对飞机刹车系统的影响,以C/C复合材料刹车盘为例,分析了影响飞机刹车过程中刹车盘摩擦系数的因素,利用BP神经网络建立摩擦系数动态模型,并将其整合到利用AMESim软件建立的飞机刹车系统模型中,进行了动态仿真分析。相对于传统的刹车系统建模仿真,考虑摩擦系数变化能更加真实地反映飞机刹车过程中各种参数的动态变化过程,能更好地模拟飞机刹车滑跑过程。     

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.