基于永磁无刷电机磁场定向控制的平台伺服控制设计

介绍了基于永磁无刷电机(Brushless DC Motor,BLDC)和磁场定向控制(FOC)的平台伺服控制系统方案.阐述了一种基于FOC的伺服控制设计方法,描述了嵌入式系统的硬件与软件实现.通过实测对比了BLDC采用FOC方法与三相六拍法时伺服控制系统的转速波动情况,结果显示采用FOC显著提高了基于BLDC的伺服控制系统性能.     

火箭发动机推力试验装置应用范围研究

提出并研究火箭发动机推力试验装置应用范围扩大问题,即推力试验装置如何适用于推力远远小于试验装置额定负荷能力的发动机的推力试验。指出并研究了其中关键技术问题,包括试验装置机械结构与发动机的安装与配合、减小测力误差和原位校准的实现。建立了有关力学模型,分析了测力误差产生原因,并提出和论证了解决措施。研究结果表明,通过合理的设计,火箭发动机推力试验装置基本上可以用于推力小于试验装置额定负荷的任何规格的发动机的推力试验。     

潜入式喷管喉衬界面间隙优化设计

为了解决固体火箭发动机潜入式喷管喉衬在热载荷与内压联合作用下界面间隙优化问题,数值模拟方法求解了喷管热结构响应.采用流体仿真软件,计算了潜入式喷管流动过程的稳态流场,获取了高温燃气流动参数与固体壁面对流换热系数.并采用三维有限元结构计算平台,编写了非均布壁面压力载荷与非均布对流换热系数子程序,求解了喉衬前后搭接界面间隙...     

用于直升机现场计量的低频振动校准技术

本文面向直升机健康与使用监测系统(HUMS)的现场计量保障需求,针对其中振动传感器在低频段尚无法实现现场校准的现状,提出了基于直线电机驱动技术的便携式低频振动校准技术方案。该方案利用高精度直线电机构造低频标准振动源,采用稳定性高的石英挠性加速度计作为标准加速度计,具有体积小、精度高、现场环境适应性好的特点,非常适用直升机HUMS的现场计量保障。根据不确定度评估结果,该方案能够实现0.5Hz～20Hz频率范围,0.01m/s~2～20m/s~2加速度范围内不超过1%的校准不确定度(k=2)。     

基于遗传算法的军事物流运输计划

针对军事物流运输中车辆装载和车辆路径的组合问题进行研究,建立车辆装载和车辆路径组合问题的目标优化模型。通过改进遗传算法对模型求解,得到了较为满意的结果,可以在满足多车型多品种货物配送约束的条件下,实现运输车辆最少、车辆满载率高、车辆运输路径最短的目标。     

Antiparticle content in the magnetosphere

In the present work we assess the stable and transient antiparticle content of planetary magnetospheres, and subsequently we consider their capture and application to high delta-v space propulsion. We estimate the total antiparticle mass contained within the Earth’s magnetosphere to assess the expediency of such usage. Using Earth’s magnetic field region as an example, we have considered the various source mechanisms that are applicable to a planetary magnetosphere, the confinement duration versus transport processes, and the antiparticle loss mechanisms. We have estimated the content of the trapped population of antiparticles magnetically confined following production in the exosphere due to nuclear interactions between high energy cosmic rays (CR) and constituents of the residual planetary upper atmosphere.The galactic antiprotons that directly penetrate into the Earth’s magnetosphere are themselves secondary by its nature, i.e. produced in nuclear reactions of the cosmic rays passing through the interstellar matter. These antiproton fluxes are modified, dependent on energy, when penetrating into the heliosphere and subsequently into planetary magnetospheres. During its lifetime in the Galaxy, CR pass through the small grammage of the interstellar matter where they produce secondary antiprotons. In contrast to this, antiprotons generated by the same CR in magnetosphere are locally produced at a path length of several tens g/cm² of matter in the ambient planetary upper atmosphere. Due to the latter process, the resulting magnetically confined fluxes significantly exceed the fluxes of the galactic antiprotons in the Earth’s vicinity by up to two orders of magnitude at some energies.The radiation belt antiparticles can possibly be extracted with an electromagnetic-based “scoop” device. The antiparticles could be concentrated by and then stored within the superimposed magnetic field structure of such a device. In future developments, it is anticipated that the energy of the captured antiparticles (both rest energy and kinetic energy) can be adapted for use as a fuel for propelling spacecraft to high velocities for remote solar system missions.     

嵌金属丝推进剂燃烧起始阶段增速特性研究

考虑了使用嵌金属丝装药的发动机工作过程中的多种因素,建立了金属丝与药柱、燃气间相互作用的控制方程组,并对方程组进行了数值求解,得到了嵌金属丝推进剂在燃烧起始阶段,增速比随时间的详细变化过程。结果表明,金属丝的热扩散率、熔点、直径和黑度以各自不同的方式影响金属丝的增速效果,熔点相对较低的金属丝可能会在内弹道曲线的初始阶段形成一个轻微的压强峰,固有燃速较低、着火温度较低的推进剂对嵌入金属丝较为敏感。文中数值方法计算量小,结果可靠,适于工程应用。     

Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas.Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB(hydroxyl-terminated polybutadiene) hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.     

Storage life of silicone rubber sealing ring used in solid rocket motor

It is urgent to carry out detailed research on storage performance of rubber sealing ring to get the criterion for its storage life. This paper acquires material ageing regularity by theoretical analysis and experimental confirmation. On this condition, failure mode and failure criterion of typical sealing structure is studied, and the failure mechanism is found. Thus by analyzing the stress distribution, the relationship between ageing state and sealing condition is established. Rationalization proposal is put forward and storage life of sealing ring is evaluated. The research mentionedabove has special reference to the design of sealing structures and can provide reference for prolonging their service life.     

无刷直流电机控制器硬件实时性设计方法

在航空领域,无刷直流电机由于其高效率及低故障率,已逐步取代传统液压作动部件.针对无刷直流电机控制器的硬件实时性设计,介绍了控制器的整体架构、各个模块功能及简单的控制流程和方法,重点讨论了控制器的双处理器交互的实时性设计,给出了优化方法,实验数据表明,优化方法达到了预期效果.