基于不同烧蚀模型的脉冲等离子体推力器壁面-等离子体交互作用的机理(英文)

Ablation excited by current pulses is a very critical physical process in pulse plasma thrusters(PPT).Its effects on wall-plasma interaction directly determine the PPT performances.In order to reveal the process of the ablated wall interaction with the discharge plasma in PPT,ablation models formulated by three different boundary conditions at the wall-plasma interface are studied.These are the two widely used high-speed evaporation models(Model-L and Model-M),and the recently developed Keida-Zaghloul model(Model-K)of the Knudsen layer that takes into account the internal degrees of freedom on the energy flux conservation.First,fundamental mechanisms of the three ablation models are clarified by comparative analysis in order to gain a comprehensive understanding of the wall-plasma interaction.Then,the applicability of different ablation models with the numerical solutions of LES-6 PPT is investigated in detail using magnetohydrodynamic(MHD)modeling.Results show that Model-L and Model-M are actually special cases of Model-K when a simplified jump conditions limited by high velocity at the vapor/plasma interface is used;A ratio of ablation rate in Model-L to that in Model-M is about 0.8at the same wall surface temperature,while it rises to 1 at different surface temperature determined by Model-L and Model-M in PPT.Even though Model-K solution requires significant computational time,it shows more accurate ablation feature for the wall-plasma interaction and possesses better computing precision of impulse bit during post-pulse which is useful for future studies of the late time ablation.     

调节系统不灵敏度的一个关系式

通过理论分析和数学推导,给出了汽轮机调节系统不灵敏度的定量关系式,探讨了调节系统不同的级成部件对整系统不灵敏度的影响的规律,并推广应用于控制系统的设计。     

固体燃料超燃冲压发动机燃烧室流动与掺混过程研究

针对固体燃料超燃冲压发动机燃烧室内不同凹腔结构的流场特性以及燃料与来流空气掺混效率进行了研完。总结了在不同结构燃烧室内流场特性,随着凹腔长深比的减少,凹腔内剪切层逐渐由偏向凹腔内部演变为偏向主流方向;同时对比燃烧室内有无凹腔结构时燃料与空气的掺混效率,说明凹腔结构对超声速气流下燃烧室内掺混效率的提高有明显的效果。     

200MW汽轮机转子泊松效应的参数识别

采用一种信号分离的方法，对200MW汽轮机转子泊松效应的参数进行了识别，分析了其物理机理，给出了最终的识别结果，对预测汽轮机差胀有参考价值。     

OBMS/IDKE 的动态横式管理

本文从各数据模型下的模式管理问题出发,讨论了面向对象数据库系统 OBMS/IDKE(Object-Base Management Sytem/Institute of Date and Knowledge Engineering)的数据模式管理所面临和待解决的复杂语义问题,并阐述了该系统模式管理的外部界面和内部实现。     

入口气流参数对固体燃料超燃冲压发动机燃烧室性能的影响分析

为了研究固体燃料超燃冲压发动机燃烧室入口气流参数对发动机性能的影响,将固体燃料燃面退移速率模型耦合到准一维流动方程中,提出了一种燃烧室的准一维设计和性能分析方法。利用该方法,在飞行条件一定的前提下,改变燃烧室入口气流参数总压、总温、马赫数,得出了各工况下的燃烧室初始型面尺寸并分析了其性能。研究结果表明：在设计飞行条件下,提高燃烧室入口气流的总压和总温均能提高燃烧室的性能,但总温对燃烧室性能的影响更大;燃烧室入口较低的马赫数可以减小燃烧室的加热损失,提高燃烧室的性能;在入口气流质量流量和台阶面积比一定的条件下,提高总温和总压、减小马赫数,能提高燃面推移速率,减小燃烧室的长度。     

机载氧源在航空领域的应用与发展趋势

通过对世界各国飞机供氧系统的调研和分析,总结了目前航空领域各种供氧方式,指出分子筛供氧是目前机载氧源发展的必然趋势,从该技术发展起来的用于油箱防火防爆的联合制氮制氧系统是新的发展方向.     

稳态等离子体发动机磁场设计的发展及其展望

论述了稳态等离子体发动机对于我国空间发展战略的重要意义和作用，指出磁场设计是提高稳态等离子体发动机性能的关键技术之一；分析了稳态等离子体发动机通道内磁场设计的发展过程，在此基础上提出了用于稳态等离子发动机磁场设计的体系化构想，并且指出了其中存在的一些关键问题和拟采取的解决措施以及磁场体系化设计对稳态等离子体发动机带来的预期效益和影响；最后展望了稳态等离子体发动机磁场设计体系的进一步发展和应用。     

Parameters Distribution Along the Channel Axis in the Scaling Designed Stationary Plasma Thruster

The study of the parameters＇ distribution along the channel axis in a stationary plasma thruster（SPT） helps One to understand the physical characteristics of the SPT＇s operation. In this paper, the axial distribution of the desired SPT parameters are predicted by combining the improved scaling theory and a one-dimensional hybrid model. The simulation indicates that the SPT parameters＇ distribution along the channel axis changes with scaling index variable ~. If ~ is set properly, the similarity of the parameters~ axial distribution between the model and a desired thruster can be ensured. In addition, the operation characteristics of the desired thruster, such as the ionization and acceleration processes, are also similar to those of the model. When ζ is set, the improved SPT scaling theory and the one-dimensional hybrid model can be used to predict the axial distribution of the desired SPT parameters with the same propellant （such as Xe）.     

基于水推进剂的脉冲等离子体推力器数值模拟

为揭示水推进脉冲等离子体推力器(WP-PPT)特有的烧蚀机理,解决WP-PPT工程化应用中所存在的关键问题,研究了WP-PPT的工作过程。建立了适用于WP-PPT的烧蚀模型,对WP-PPT的工作过程进行了仿真。将仿真结果与东京大学的实验结果进行比较。比较结果表明:由于部分推进剂气化或残留在通道内,仿真性能与实验结果不符;在样机的工作参数条件下,当参与放电的推进剂占总推进剂质量的20%时,仿真结果与实验结果较为相符;仿真结果中的元冲量、比冲以及能量转化效率分别为74μN.s、1 114s以及15.2%。分析实际实验过程,估算出约32%的推进剂参与放电,与仿真结果相近。研制快响应、高喷注均匀性的喷注器可提高WP-PPT性能。