LPP低污染燃烧室两相喷雾燃烧数值研究

提出一种带有多点燃油直接喷射双环预混旋流(TAPS/MLDI)头部的贫油预混预蒸发(LPP)低污染圆筒燃烧室,为了获得该燃烧室两相喷雾燃烧流场与燃烧性能,利用Fluent数值研究三种LPP燃烧室头部方案和四种进口工况.计算结果表明:(1) LPP燃烧室头部冷态流场存在中心回流区、角落回流区和唇口回流区,流场结果与PIV试验结果吻合较好.(2)在头部方案不变的情况下,工况从100％推力下降到7％推力时,出口平均温度逐渐下降,污染物NOx排放相应减少.(3)在进口工况不变时,头部方案B燃烧性能相对最优.(4)热力型NOx的生成速率与燃气温度超过1950K区域的大小和最高燃气温度直接相关,热力型NOx的生成主要分布在火焰锋面附近.     

基于粒子群算法的航空离心泵复合叶轮优化设计研究

针对航空离心泵复合叶轮三元扭曲型线的优化设计问题,基于Matlab平台采用五点四次Bezier曲线控制四条轴面流线的空间圆周角度分布,实现复合叶型的参数化设计。在此基础上,应用批处理联合仿真方法对125组优化空间样本进行数值模拟,并以效率函数为目标,基于高斯型径向基函数构建复合叶轮型线参数的性能代理模型。最后采用粒子群算法对优化设计参数进行全局寻优搜索。结果表明,代理模型的修正复相关系数为0.9269,标准差为0.1036,能够满足参数预测的性能要求,优化后整泵水力效率提高2.72%。     

Study of the 28 October 2003 and 20 January 2005 solar flares by means of 2.223 MeV gamma-emission line

By the data on intensity-time profiles of the neutron capture line of 2.223 MeV we have studied some characteristics of two solar flares, 28 October 2003 and 20 January 2005 (INTEGRAL and CORONAS-F observations, respectively). The SINP code was applied making allowance for the main processes of neutron interactions and deceleration in the solar plasma, character of neutron source, losses of neutrons and density model of the solar atmosphere. Comparison of the computed time profiles of 2.223 MeV line with observed ones for the flare of 28 October 2003 confirms the results obtained earlier for three other flares. Namely, the effect of density enhancement (EDE) in the sub-flare region, as well as the variations (hardening) of accelerated particle spectrum in the course of the event have been confirmed. The usual modeling procedure by the SINP code, however, seems to be inapplicable to the event of 20 January 2005. Possible causes of density enhancements during some flares and peculiarities of the 20 January 2005 flare are discussed.     

Cosmic Ray research in Armenia

Cosmic Ray research on Mt. Aragats began in 1934 with the measurements of East–West anisotropy by the group from Leningrad Physics-Technical Institute and Norair Kocharian from Yerevan State University. Stimulated by the results of their experiments in 1942 Artem and Abraham Alikhanyan brothers organized a scientific expedition to Aragats. Since that time physicists were studying Cosmic Ray fluxes on Mt. Aragats with various particle detectors: mass spectrometers, calorimeters, transition radiation detectors, and huge particle detector arrays detecting protons and nuclei accelerated in most violent explosions in Galaxy. Latest activities at Mt. Aragats include Space Weather research with networks of particle detectors located in Armenia and abroad, and detectors of Space Education center in Yerevan.     

Enhancing the ATIC charge resolution

The Advanced Thin Ionization Calorimeter (ATIC) experiment is designed to investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 10¹¹ to 10¹⁴ eV during Long Duration Balloon (LDB) flights from McMurdo, Antarctica. Currently, analysis from the ATIC-1 test flight and ATIC-2 science flight is underway and preparation for a second science flight is in progress. Charge identification of the incident cosmic ray is accomplished, primarily, by a pixilated Silicon Matrix detector located at the very top of the instrument. While it has been shown that the Silicon Matrix detector provides good charge identification even in the presence of electromagnetic shower backscatter from the calorimeter, the detector only measures the charge once. In this paper, we examine use of the top scintillator hodoscope detector to provide a second measure of the cosmic ray charge and, thus, improve the ATIC charge identification.     

高动态下惯性加速度辅助三阶锁相环性能分析

针对高阶跟踪环路稳定性比低阶环路差,大带宽带来测量误差大的问题。研究在高动态环境下,惯导加速度信息辅助卫星接收机三阶载波锁相环跟踪算法,以及不同环路参数下跟踪环路的性能。对载体高动态场景、加速度信息延迟进行建模,并对算法进行了数学仿真。仿真分析结果表明,在加速度信息辅助下,即使压缩载波跟踪环路等效噪声带宽到3Hz,在高达1200g/s的加速度动态下,环路跟踪同样稳定可靠。     

考虑电荷交换的三维离子发动机栅极粒子模拟

为了对离子发动机光学系统进行数值分析，开发了考虑电荷交换的三维离子发动机栅极粒子模拟程序。模拟程序采用单元内粒子（PIC）方法，光学系统为双栅极结构，推进剂采用氙，总加速电压为1600V，栅极间距为1mm，粒子之间的电荷交换碰撞模型采用蒙特卡洛方法。采用链式存储结构存储粒子信息，可以实现数组式存储方法所不能实现的功能。使用粒子模拟程序对离子发动机光学系统进行了粒子模拟，模拟得到了栅极间的电场分布和氙离子空间分布。模拟结果表明，在所取工作参数下氙离子全部通过了栅极孔，未撞击到栅极上，验证了参数的合理性。     

The beginning of cosmic ray astrophysics

A short history of the beginning of cosmic ray (CR) astrophysics is considered: from the hypothesis on CR origin as a result of Supernova explosions in the Metagalaxy, to a model of solar origin of CR, galactic origin based on the stochastic mechanism of charged particle acceleration in interstellar space, to extragalactic and hierarchical models of CR origin, as well as galactic CR origin taking into account radio-astronomical data. We consider also the first balloon results on the chemical contents of primary CR (especially of the contents Li, Be, B), important for any model of CR origin. Investigations of the injection problem, CR drift and diffusion acceleration by shock waves, and CR generation in Supernova remnants were also important steps in the beginning of CR astrophysics.     

Reconnection and fast particle production in tokamak and solar plasmas

Detailed in situ studies of magnetic reconnection and particle acceleration, which play a crucial role in the release and redistribution of energy in solar flares, can be performed in tokamak plasmas under conditions resembling those of the flaring solar corona. Recent measurements and modelling of fast particle production during reconnection events in the Mega-Amp Spherical Tokamak (MAST) are described. Specifically, observations in this device of electron acceleration during edge localised modes, and of both ion and electron acceleration during merging-compression plasma start-up, are presented, and possible implications of these studies for particle acceleration in flares are discussed. The results from MAST lend weight to the conjecture that large numbers of ions are accelerated to sub-MeV energies in flares.     

欧洲计算流体力学——个人观点

介绍了70年代初到20世纪末欧洲科学家对CFD发展的主要贡献,并重点关注了对国际流体力学数值方法会议(ICNMFD)和国际计算力学学术会议(ISCFD)的成功举办具有重大贡献的科学家.ICNMFD始于1969年(新西伯利亚),由参与了美国和苏联太空竞赛的两国科学家联合创办,而ISCFD则作为ICNMFD在亚太地区的同类会议初创于1995年(东京).由Oshima教授和本人提议,得益于上述两个会议全体科学委员会成员的共同努力,ICNMFD和ISCFD自2000年开始,合并成为每两年举办一次的国际计算流体力学会议(ICCFD).绝大部分本文讨论所涉及的学者通常都在受邀进行大会报告后,成为了前述三大国际会议中的一个或多个科学委员会的成员.作者对文中讨论所涉及的研究人员的圈定负有全权责任,上述人员的选择更多地基于应用而非理论计算流体力学,因此尚存在不完善之处.此外由于文中所讨论的学者大都是作者在40多年计算流体力学研究生涯中的私交好友,因此并没有将年轻一代的科学家考虑进来,但这并非由于他们的贡献不重要.另外值得注意的是欧洲的计算流体力学同美国的计算流体力学有非常紧密的联系,本文讨论所涉及的研究学者有些最早从欧洲开始涉足计算流体力学而现在则生活和工作于美国(例如Glowinski,Roe,Van Leer等人),而有些则是在美国取得了博士学位(例如Launder,Napolitano),他们都同美国的科学家进行过合作,因此很难清晰地对欧洲和美国的计算流体力学进行界定.对那些现已移居美国的欧洲科学家们,本文优先考虑了他们移居之前的贡献.最后但并非是最不重要的,作者通过电子邮件一一联系了文中所涉及的科学家,希望他们本人能够给出其自身贡献的评价草稿,从而帮助作者以最权威的视角在文中相应章节对其工作进行评述.本文向提供自述评价的诸位致以谢意,同时也希望其他同仁能够对本人不恰当的擅自评述给予谅解.