尖化前缘高导热材料防热分析

针对飞行器高超声速飞行时严重的气动加热环境,提出疏导式热防护结构( TPS),为飞行器前缘提供热防护.采用有限元法和有限体积法,分别对在特定工况下飞行的尖化前缘固体域和流体域进行计算,验证了前缘内嵌高导热材料的防热效果,其中来流马赫数为6.5时,头部壁面最高温度下降了13.6％,尾部最低温度升高了16.7％,实现了热流...     

Broadening of Fe X (6374 Å) profiles above the limb in a coronal hole

Profiles of the visible Fe X (6374 Å) coronal emission line as a function of height above the limb were obtained out to 1.16 solar radii in a coronal hole using the NSO/Sacramento Peak Observatory Coronagraph, Universal Spectrograph and a CCD camera. These are the first coronal line profiles obtained as a function of height in a coronal hole from the ground. Analysis of the line widths suggests a large component of nonthermal broadening which increases with height ranging from 40 to 60 km/s, depending upon the assumed temperature or thermal component of the profile.     

尖前缘翼干扰区的壁面压力和热流率分布

本文给出Ｍ＿∞＝７．８和６．７２，Ｒｅ＝３．５×１０￣７／ｍ和５．４×１０￣７／ｍ气流绕迎角为２０°、３０°和３５°尖前缘翼运动时，平板锥型干扰区的壁面压力和热流率分布。结果表明：（１）平板锥型干扰区的特征几何尺度与无粘激波角β＿０和翼迎角α相关，而壁面压力和热流率的峰值与法向马赫数Ｍ＿ｎ相关。（２）翼面压力和热流率分布由于受拐角涡影响，前者在翼根部呈波谷状，而后者呈波峰状，影响尺度与翼前缘处来流边界层厚度有关。     

涡流管结构参数对其性能的影响

用实验方法研究了热端管管长、分离室直径、冷孔板孔径等主要结构参数对涡流管的制冷制热性能的影响。实验中以空气为介质分别对不同结构参数涡流管的性能进行了研究,得出了热端管管长、分离室直径以及冷孔板孔径等参数对涡流管制冷制热性能的影响规律。研究结果表明:在一定范围内增加热端管长度有利于涡流管的能量分离;在大冷流率下,大直径涡流管的制冷性能优于小直径涡流管;冷孔板孔径愈小,涡流管的制冷制热效应都愈好,在冷孔板孔径与热端管内径之比为50%时,取得最佳的制冷制热效应。      

添加剂含量对二硅化钼发热体抗氧化性能的影响研究

研究了添加剂含量对MoSi2发热体性能的影响,使用SEM观察各种添加剂含量试样的微观组织,测定各种添加剂含量试样的氧化动力学曲线、致密度、烧损温度。     

Dynamics of Coronal Loop Oscillations Recent Improvements and Computational Aspects

We will discuss the observed, heavily damped transversal oscillations of coronal loops. These oscillations are often modeled as transversal kink oscillations in a cylinder. Several features are added to the classical cylindrical model. In our models we include loop curvature, longitudinal density stratification, and highly inhomogeneous radial density profiles. In this paper, we will first give an overview of recently obtained results, both analytically and numerically. After that, we shed a light on the computational aspects of the modeling process. In particular, we will focus on the parallellization of the numerical codes.     

On the Coronal Magnetic Field Configuration and Solar Flare/CME Process

The coronal magnetic field configuration is important for understanding the energy storage and release processes that account for flares and/or CMEs. Here we present a model which is based on the work for potential magnetic field problems that only applies the condition at infinity with the boundary condition on the solar surface specified. We also discuss some recent progress on general force-free field models. For some event analyses, we have employed MDI/SOHO longitudinal magnetogram insected into the synoptic magnetogram to obtain whole boundary condition over the solar surface. Globally, the extrapolated global magnetic field structures effectively demonstrate the case for the disk signature of the radio CMEs and the evolution of the radio sources during the CME/flare processes.     

带冠整体叶轮通道加工方法的分析和探索

讨论了整体叶轮应用于现代发动机的发展趋势及其制造难点。在分析现有加工工艺的基础上,提出了适用于带冠整体叶轮叶片型面的新型加工方法——电解加工与电火花加工的组合工艺。     

Composition Variations in the Solar Corona and Solar Wind

Order of magnitude variations in relative elemental abundances are observed in the solar corona and solar wind. The instruments aboard SOHO make it possible to explore these variations in detail to determine whether they arise near the solar surface or higher in the corona. A substantial enhancement of low First Ionization Potential (FIP) elements relative to high FIP elements is often seen in both the corona and the solar wind, and that must arise in the chromosphere. Several theoretical models have been put forward to account for the FIP effect, but as yet even the basic physical mechanism responsible remains an open question. Evidence for gravitational settling is also found at larger heights in quiescent streamers. The question is why the heavier elements don't settle out completely. This revised version was published online in June 2006 with corrections to the Cover Date.     

UVCS/SOHO Observations of Spectral Line Profiles in Polar Coronal Holes

Ultraviolet emission line profiles have been measured on 15-29 September 1997 for H I 1216 Å, O VI 1032, 1037 Å and Mg X 625 Å in a polar coronal hole, at heliographic heights ? (in solar radii) between 1.34 and 2.0. Observations of H I 1216 Å and the O VI doublet from January 1997 for ? = 1.5 to 3.0 are provided for comparison. Mg X 625 Å is observed to have a narrow component at ? = 1.34 which accounts for only a small fraction of the observed spectral radiance, and a broad component that exists at all observed heights. The widths of O VI broad components are only slightly larger than those for H I at ? = 1.34, but are significantly larger at ? = 1.5 and much larger for ? > 1.75. In contrast, the Mg X values are less than those of H I up to 1.75 and then increase rapidly up to at least ? = 2.0, but never reach the values of O VI.