Design and Stability of Operating Mechanism for a Spacecraft Hatch

This article introduces the working principles of a spacecraft hatch including its operating process and moving trajectory. On this basis, an operating mechanism is designed to execute automatic open and close action of the hatch and measure the operating torques. Analysis on the mechanism's configuration and topological structure of each phase of movement proves that it is a typical variable freedom mechanism. The mechanism manipulates the hatch in accordance with the moving trajectory requirements through configuration transformation. Kinematic analysis and simulation of some typical configurations show that the velocity differences among mechanism components themselves and the components and their abutting components could exert influences on its working stability during configuration transformation. To solve the problem, stability conditions of configuration transformation are proposed. Appropriate control models are established for the output velocity curves of the driving servo motor and solved based on the stability conditions and rules of movement. Results from another simulation demonstrate that the proposed control models ensure smooth configuration transform and stable operation.     

流量调节器管路系统自激振荡特性研究（液体火箭推进专刊）

流量调节器管路系统在小流量大压降工况下会出现低频自激振荡现象,为了深入认识自激振荡产生机理,结合某型自稳流型流量调节器及管路系统,基于流量调节器弹簧振子动力学模型开展数值仿真研究。数值仿真得出自激振荡频率为94 Hz,与发动机试验结果一致。自激振荡产生机理是流量调节器的液动力受滑阀窗口型面变化率影响对系统形成正反馈作用,流量调节器综合刚度小于零时系统失稳。分析了流量调节器结构参数对系统稳定性的影响作用,三角形滑阀节流口流通面积能够抑制管路系统自激振荡。结合某型流量调节器负载特性试验系统进行验证,得出随着流量调节器压降升高,管路系统稳定性变差,获得的幅频特性,稳定边界与试验结果一致。     

减压器动态仿真的有限体积模型

通过对一维理想气体流动的有限元状态变量模型推导过程的拓展，获得了适用于变体积容腔的气体容积模型，并结合气体管道、气体阀门的有限元状态变量模型，通过对三者的组合运用发展了一种可仿真气体减压器动态工作过程的有限体积模型。采用此模型分别对某逆向卸荷膜片式减压器和某贮箱增压系统所用减压器进行了动态工作过程的仿真，前者仿真结果的稳态值与早期文献的实验数据和仿真结果相一致。表明有限体积模型的稳态精度合乎工程需要；后者的仿真获得了减压器各个腔室状态参数和阀芯开度的响应曲线，表明贮箱增压过程可以分为启动段、稳定段两个阶段，同时表明在理想气体绝热流动的假设下节流前后温度基本不变。数学模型和建模方法显示出良好的有效性和通用性。     

弹用涡喷发动机的动态仿真研究

采用变比热容的方法及容积积累模型,建立了调节系统及发动机主要部件的动力学方程,对某弹用涡喷发动机的过渡态进行了模拟仿真。结果表明：该发动机转速特性典型,加速性好,仿真数模及程序有较好的可信度。此外,还分析了涡喷发动机的仿真特点和仿真中必须解决的关键问题。     

Large-signal stability analysis of solar array power system

A large-signal stability analysis of the solar array regulator system is performed to facilitate the design and analysis of a low-earth-orbit (LEO) satellite power system. The effective load characteristics of various control methods in the solar array regulator system, such as the constant power load, variable power load, constant voltage load, constant current load, and constant resistive load, are classified to analyze the large-signal stability. Then, using the state plane analysis technique, the large-signal behavior of the solar array system is portrayed and the stability of various equilibrium points is analyzed. Thus, this approach can be contributed to organize the optimal controller structure of the system by representing the relationship between the control method of the solar array regulator and the large-signal stability. For the verification of the proposed large-signal analysis, a solar array regulator system that consists of two 100 W parallel module buck converters has been built and tested using a real 200 W solar array.     

On Lyapunov stability analyses of the switching regulator/filtersystem

The stability design criteria for the fourth-order switching regulator/low-pass filter system are obtained directly from the solution to the resultant simultaneous equations for the Lyapunov matrix equation. The regulator/filter system is asymptotically stable if the values of the filter components are chosen to satisfy the derived Lyapunov stability design criterion for a given value of the switcher dynamic resistance     

大型训练模拟器网络系统设计

大型训练模拟器是一个典型的分布式仿真系统(DIS),计算机网络系统是其核心组成部分。文中介绍了一种采用两级网络结构的设计方案．详细说明了网络系统的软硬件组成和控制方式,并说明了HLA标准在系统中的作用。     

固液混合火箭发动机仿真与优化设计

建立了固液混合火箭发动机的仿真模型和相应的单目标和多目标优化模型,编制了系统仿真程序;采用差分进化算法针对不同的优化目标对发动机的参数进行优化;针对挤压式系统建立了质量模型,在优化过程中考虑了主要部件结构质量对发动机性能的影响;针对固液发动机常用的侧面燃烧药柱编制了内弹道计算程序。以药柱几何参数、氧化剂流量、燃烧室平均工作压强和喷管扩张比等参数为设计变量,对发动机平均比冲、总质量、关机时飞行速度和密度比冲等性能参数进行优化,在Pareto分析的基础上选择了氧化剂流量、燃烧室平均工作压强和喷管扩张比对发动机性能的影响作了深入研究;最后对某型固液发动机进行了优化分析。     

空对空导弹攻击在综合火力／飞行控制中的设计、仿真

研究空－空导弹攻击在综合火力／飞行控制（ＩＦＦＣ）系统中的设计与仿真问题,给出了ＩＦＦＣ系统的结构、组成及仿真信息流图。探讨了中程导弹拦射攻击的火力控制算法,并且详细地讨论了火力／飞行耦合器的设计方法及组成。最后,采用五自由度非线性飞机方程及三轴ＡＣＴ控制增稳系统,进行了整个火力／飞行系统的数字仿真。在仿真的基础上,设计了一些典型作战条件下的火力／飞行耦合控制器的参数。仿真结果表明：综合火力／飞行控制系统可以实现导弹攻击的自动化,同时也说明本文设计的火力／飞行耦合器具有很强的鲁棒性能     

减压器动态过程的数值仿真

针对贮箱增压过程和发动机工作过程中减压器的动态调节,建立了液体火箭发动机常用的反向卸荷式减压器的动态数学模型,采用四阶龙格-库塔方法进行了数值仿真,分析了减压器在启动增压过程中的动态特性,得到不同入口压力下减压器的出口压力与试验数据相一致的结论。表明所建立的数学模型准确,采用的仿真方法符合精度要求,对同类减压器的设计和系统分析具有一定的指导作用。      

Numerical simulation of a cabin ventilation subsystem in a space station oriented real-time system

An environment control and life support system(ECLSS) is an important system in a space station. The ECLSS is a typical complex system, and the real-time simulation technology can help to accelerate its research process by using distributed hardware in a loop simulation system. An implicit fixed time step numerical integration method is recommended for a real-time simulation system with time-varying parameters. However, its computational efficiency is too low to satisfy the real-time data interaction, especially for the complex ECLSS system running on a PC cluster. The instability problem of an explicit method strongly limits its application in the ECLSS real-time simulation although it has a high computational efficiency. This paper proposes an improved numerical simulation method to overcome the instability problem based on the explicit Euler method. A temperature and humidity control subsystem(THCS) is firstly established, and its numerical stability is analyzed by using the eigenvalue estimation theory. Furthermore, an adaptive operator is proposed to avoid the potential instability problem. The stability and accuracy of the proposed method are investigated carefully. Simulation results show that this proposed method can provide a good way for some complex time-variant systems to run their real-time simulation on a PC cluster.     

基于EHA的多轮系飞机刹车系统的建模与仿真

介绍了一种采用电动静液作动器(EHA)代替原有液压作动机构的飞机多轮系防滑刹车系统,在重点分析EHA的系统组成原理和工作特性的基础上.建立了EHA及多轮系飞机刹车系统的数学模型,采用Matlab/simulink对其进行仿真.仿真结果表明:所建立的模型基本正确,结果与真实刹车基本吻合;采用EHA代替液压系统能极大改善飞机刹车性能.     

基于死区补偿的氧调器平稳切换自抗扰控制

歼击机中供氧系统内的氧气气压调节系统（氧调器系统）对飞行员的飞行质量至关重要。但是氧调器系统易受飞行环境和飞行员呼吸状态等因素的影响,而且氧调器所用阀门大多含有死区,会给控制系统带来稳态误差,导致控制难度增大,一般的控制策略难以兼顾补偿较大死区和抗扰两个条件。针对此问题,建立了基于音圈电机驱动阀的氧调器系统模型,并针对模型死区特性采用了死区补偿和双限幅模块,设计了基于死区补偿的平稳切换自抗扰控制策略。仿真及对比结果表明：采用同一套控制参数,可以使氧气面罩内压强在各个呼吸频率时有效,并快速地控制在呼吸阻力容许界限以内;并且其呼吸阻力低于将死区看作扰动的一般自抗扰控制（ADRC）。同时,验证了此策略的鲁棒性和抗扰性。     

机载蒸发循环系统动态仿真

从部件的数学模型出发,根据闭环系统各部件的耦合关系,建立了机载蒸发循环系统的动态数学模型。对充注R142b的机载蒸发循环系统进行了动态仿真,仿真数据与试验数据基本吻合,仿真方法可靠,可以作为机载蒸发循环系统优化及系统控制的依据。     

A novel multi-fidelity coupled simulation method for flow systems

For the numerical simulation of flow systems with various complex components, the traditional one-dimensional (1D) network method has its comparative advantage in time consuming and the CFD method has its absolute advantage in the detailed flow capturing. The proper coupling of the advantages of different dimensional methods can strike balance well between time cost and accuracy and then significantly decrease the whole design cycle for the flow systems in modern machines. A novel multi-fidelity coupled simulation method with numerical zooming is developed for flow systems. This method focuses on the integration of one-, two-and three-dimensional codes for various components. Coupled iterative process for the different dimensional simulation cycles of sub-systems is performed until the concerned flow variables of the whole system achieve convergence. Numerical zooming is employed to update boundary data of components with different dimen-sionalities. Based on this method, a highly automatic, multi-discipline computing environment with integrated zooming is developed. The numerical results of Y-Junction and the air system of a jet engine are presented to verify the solution method. They indicate that this type of multi-fidelity simulationmethod can greatly improve the prediction capability for the flow systems.     

使用BP神经网络模型研究逆向卸荷膜片式减压器的稳定性能

采用数据挖掘中BP(back propagation)神经网络模型来研究逆向卸荷膜片式减压器的结构参数与稳定性能之间的依赖关系,得到结构参数变化,尤其是多结构参数耦合变化下减压器的稳定性结果.其中稳定性对阻尼孔直径、膜片刚度非常敏感,对弹性元件材料的阻尼系数、低压腔有效长度较为灵敏.由此提出减弱振荡的各种措施:增大阻尼孔直径、增大膜片刚度、在一定范围(标准值的6.5倍)内增大弹性元件材料的阻尼系数、增大低压腔有效长度、减小阀芯质量.数值实验误差分析表明:该模型不存在过拟合、局部最优的情况,其预测结果是可靠的,可为减压器的设计和系统分析提供决策支持.而且,该模型对不同类型的数据集具有通用性,可以用来研究其他部件的结构参数与性能指标的依赖关系.      

Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅱ： Numerical Simulation of Bird Impact

Bird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carded out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results.     

Multiradar Tracking System Using Radial Velocity Measurements

Multiradar tracking using both position and radial velocity measurements is discussed. The measurement of two or more different radial velocity components allows the calculation of rectangular velocity components. The measurement noise of the velocity components is filtered using a Kalman filter in the same way as the Cartesian position components. Before the conversion of velocity components from radial to Cartesian coordinates, the radial velocities are aligned on a time scale to account for the time shift of the radar measurements. In order to compare multiradar tracking system performance with and without radial velocity, some simulation tests have been performed for typical paths. The simulation results show a significant improvement when radial velocity is used for tracking.     

航空发动机风扇转子叶片外物损伤II.鸟撞击数值仿真(英文)

鸟撞击是飞行安全最严重的威胁之一。鸟撞击的后果非常危险,因而,在进入服役之前,飞机部件必须通过抗鸟撞认证。航空发动机风扇转子叶片是容易受到飞鸟撞击的飞机部件之一,在设计时必须考虑使航空发动机风扇转子叶片具有抗鸟撞击的能力,降低由于鸟撞击叶片而引起的飞行事故。采用接触冲击算法,对航空发动机风扇转子叶片进行了模拟鸟撞击数值仿真。针对风扇叶片具有阻尼凸台的特点,分析中建立了三叶片组计算模型。得到了对应试验测试点的模拟鸟撞击叶片的瞬态响应曲线、叶片的位移和当量应力。比较了试验中和数值仿真中模拟鸟撞击叶片的瞬态响应曲线,试验中测试点与数值仿真中对应点的变化基本相同。分析了叶片的变形过程、最大位移和最大当量应力。模拟鸟撞击风扇叶片数值仿真验证并补充了模拟鸟撞击风扇叶片试验结果。     

某型航空发动机起动调节器建模及起动特性研究

以流量连续方程和力平衡方程为基础,采用线性化方法,建立了航空发动机起动调节器各部件和系统的数学模型。仿真分析了系统中某些部件参数的改变对起动过程的影响,从而为系统的加工、维修、装配与性能调整提供了理论依据