Calculation of high-temperature insulation parameters and heat transfer behaviors of multilayer insulation by inverse problems method

In the present paper, a numerical model combining radiation and conduction for porous materials is developed based on the finite volume method. The model can be used to investigate high-temperature thermal insulations which are widely used in metallic thermal protection systems on reusable launch vehicles and high-temperature fuel cells. The effective thermal conductivities（ECTs） which are measured experimentally can hardly be used separately to analyze the heat transfer behaviors of conduction and radiation for high-temperature insulation. By fitting the effective thermal conductivities with experimental data, the equivalent radiation transmittance, absorptivity and reflectivity, as well as a linear function to describe the relationship between temperature and conductivity can be estimated by an inverse problems method. The deviation between the calculated and measured effective thermal conductivities is less than 4%. Using the material parameters so obtained for conduction and radiation, the heat transfer process in multilayer thermal insulation（MTI） is calculated and the deviation between the calculated and the measured transient temperatures at a certain depth in the multilayer thermal insulation is less than 6.5%.     

长时间气动加热飞行器的隔热机理

主要论述长时间气动加热飞行器热防护系统隔热机理的新概念，提出传统的单相固体热传导由于其隔热机制的局限性，已不能解决新型高超声速式飞行器的隔热问题，代之以气-固的辐射-传导-对流复合传热机制。多相复合传热机理可解决长时间气动加热飞行器隔热的问题。     

红外辐射大气透过率的工程计算

针对现有红外辐射大气透过率经验计算公式不适用于高层大气的局限性,对其进行了重新推导并引入了高度修正,修正后的公式可用于计算任意高度路程上的大气透过率,修正所需大气光学特性参数全部可查相关手册获得。此外,还设计了适合于计算倾斜路径上大气透过率的计算流程,并给出了计算实例。     

淬硬不锈工具钢高速铣削工艺

结合生产,对S-136淬硬钢高速铣削工艺的刀具选择、冷却方式、进给路线进行了分析。结果表明,对具有大而平底面的模具型腔进行高速铣削时宜采用TiAlN涂层的圆角平头铣刀,使用油雾冷却,进给路线宜采用斜坡切入的圆弧进给方式。     

燃烧室中辐射热流分布的蒙特卡罗计算

本文用蒙特卡罗法计算了燃烧室壁面辐射热流密度分布。计算中考虑了燃气参数如:压力、温度、燃气组分及燃气的吸收和发射特性沿燃烧室轴向、径向和周向的变化。详细地说明了计算过程并进行了算例计算。计算所得热流密度值与分布规律是合理的。      

High energy radiation from the direction of the galactic black hole Sgr A

X-ray observations indicate that the Galactic black hole Sgr A^∗ is inactive now, however, we suggest that Sgr A^∗ can become active when a captured star is tidally disrupted and matter is accreted into the black hole. Consequently the Galactic black hole could be a powerful source of relativistic protons with a characteristic energy ∼10⁵² erg per capture. The diffuse GeV and TeV γ-rays emitted in the direction of the Galactic Center (GC) are the direct consequences of p–p collisions of such relativistic protons ejected by very recent capture events occurred ?10⁵ yr ago. On the other hand, the extended electron-positron annihilation line emission observed from GC is a phenomenon related to a large population of thermalized positrons, which are produced, cooled down and accumulated through hundreds of past capture events during a period of ∼10⁷ yr. In addition to explaining GeV, TeV and 511 keV annihilation emissions we also estimate the photon flux of several MeV resulting from in-flight annihilation process.     

空间光学遥感器天然辐射效应数据库研究

空间环境是诱发卫星异常和故障的主要原因之一。光学遥感器作为卫星最重要的有效载荷之一,在空间会受到空间辐射环境的影响。因此在研制光学遥感器的同时,需要同时考虑空间辐射环境因素,文章就空间光学遥感器天然辐射效应数据库的设计和应用进行了介绍。     

SOI工艺抗辐照SRAM型FPGA设计与实现

为提升SRAM型FPGA电路块存储器和配置存储器抗单粒子翻转性能，本文提出一种脉冲屏蔽SRAM单元结构。该结构通过在标准的六管单元中加入延迟结构,增大单元对单粒子事件响应时间，实现对粒子入射产生的脉冲电流屏蔽作用。以64k SRAM作为验证电路进行单粒子翻转性能对比，电路的抗单粒子翻转阈值由采用标准六管单元的抗单粒子翻转阈值大于25 MeV·cm 2·mg -1 提升至大于45 MeV·cm 2·mg -1 ，加固单元面积较标准六管单元增大约21.3%。30万门级抗辐照FPGA电路通过脉冲屏蔽单元结合抗辐照SOI工艺实现，其抗辐照指标分别为：抗单粒子翻转阈值大于37.3 MeV·cm 2·mg -1 ，抗单粒子锁定阈值大于99.8 MeV·cm 2·mg -1 ，抗电离总剂量能力大于200 krad(Si)。     

Parallel algorithm and its convergence of spatial domain decomposition of discrete ordinates method for solving radiation heat transfer problem

To improve the computational efficiency and hold calculation accuracy at the same time,we study the parallel computation for radiation heat transfer. In this paper, the discrete ordinates method(DOM) and the spatial domain decomposition parallelization(DDP) are combined by message passing interface(MPI) language. The DDP–DOM computation of the radiation heat transfer within the rectangular furnace is described. When the result of DDP–DOM along one-dimensional direction is compared with that along multi-dimensional directions, it is found that the result of the latter one has higher precision without considering the medium scattering. Meanwhile, an in-depth study of the convergence of DDP–DOM for radiation heat transfer is made. Analyzing the cause of the weak convergence, we relate the total number of iteration steps when the convergence is obtained to the number of sub-domains. When we decompose the spatial domain along one-,two- and three-dimensional directions, different linear relationships between the number of total iteration steps and the number of sub-domains will be possessed separately, then several equations are developed to show the relationships. Using the equations, some phenomena in DDP–DOM can be made clear easily. At the same time, the correctness of the equations is verified.     

Charged particles on the Earth–Jupiter–Europa spacecraft trajectory

Charged particle fluxes on the trajectory of future Russian space research mission to Jupiter and its satellite Europa are investigated. The existing experimental data and models of Jupiter’s main magnetic field and radiation belts are summarized. Preliminary results of computations of energetic particle fluxes and radiation doses for each stage of the flight are given. Special attention is paid to estimation of radiation conditions in Europa’s orbit and on its surface; influence of the satellite on spatial distribution of the fluxes of charged particles of various energies is studied.