内爆磁通量压缩过程的一维磁流体计算及分析

在一维内爆磁流体力学编码MC11D的基础上,引入了解析形式的状态方程组。利用改造后的编码对样品为铜材料的柱面内爆磁通量压缩实验进行了模拟,得到了样品管内壁的速度历史,材料的p-V关系曲线以及温升曲线。与原编码利用列表式状态方程数据库计算的结果比较,由两种状态方程模拟得到的速度曲线符合程度很好,所得p-V曲线的最大相对偏差为6.6%,温升曲线基本吻合,且模拟的速度曲线与实验结果符合较好。通过对MC11D编码的改造,拓展了其应用范围,使其可对未包含于现有列表式状态方程数据库中的材料进行模拟,为实验结果分析及数据处理提供了一种方法。     

航空复合涂层材料的激光烧蚀效应

针对航空激光防护技术研究需求,开展了复合涂层材料的激光烧蚀效应综合研究。采用圆棒固体激光器作为测试光源,搭建了具有在线温度测量功能的烧蚀实验平台。在此基础上,对聚碳硅烷(PCS)涂层样品开展了激光烧蚀实验。通过对烧蚀区域形貌和温度数据的对比分析,证明了PCS复合材料具备显著的激光防护作用。同时,从理论方面对涂层的激光防护机理进行了研究,基于材料热传导方程,建立了激光烧蚀过程的热力学模型,对温度场变化进行了模拟。研究结果表明,在复合涂层的保护下,kW级激光仅产生百℃的金属基底升温。     

电子束辐照效应的数值模拟

论述了电子束辐照材料时的能量沉积Monte-Carlo计算,在此基础上,与弹塑性流体力学方程组相结合,给出电子束激发的热一力学效应的数值模拟方法.对一系列电子束打铝靶实验进行了实际计算,得到与实验比较一致的结果.     

温室效应模拟实验装置

根据温室效应的产生原理设计制作了温室效应模拟实验装置.装置由温室、模拟地面、模拟太阳、温室保温层以及隔热水槽等部分组成.用数字温度计来测定温室温度变化值.当HFC-134a(四氟乙烷)当作与空气对比的温室气体时,在25～30 min内出现了0.5～0.6℃的温差,在1 h出现了约1℃的温差.该装置具有使用方便、实验操作简单、实验现象明显等特点,能够较好地展示温室效应现象.     

ARGO实验探测γ暴的灵敏度研究

西藏羊八井ARGO实验是对广延大气簇射事例进行观测研究的"全覆盖式"地面宇宙线观测实验, 其主要目的之一就是探测E>10GeV的γ暴. 通过Monte Carlo模拟, 估算了ARGO实验探测10GeV γ暴所具有的灵敏度.     

聚乙烯醇薄膜的红外吸收特性与保温性的关联

将聚乙烯醇(PVA)、聚乙烯(PE)、乙烯-乙酸乙烯酯共聚物(EVA)吹制成膜,分别研究了三种薄膜的光学性能、红外透射率及其对农业温室增温、保温能力的影响。PVA薄膜雾度值较PE和EVA薄膜分别降低了15%和12%,可有效提升薄膜覆盖温室的白日增温能力;在温室夜晚辐射散热集中的7～14μm波长范围内,PVA薄膜的红外透射率仅为16.2%,比EVA棚膜低20%,比PE棚膜低50%,PVA薄膜覆盖温室可大幅提高温室保温能力。     

半球头和平头试件的泰勒撞击

为研究不同头型对泰勒(Taylor)撞击载荷的影响,在材料静动态力学性能实验和Taylor撞击实验的基础上进行数值模拟,分析试件在撞击过程中的接触力、速度和外形尺寸等参量的变化历程。结果表明:在相同的撞击速度下,半球头试件的塑性变形程度更大;半球头试件的撞击载荷上升沿变缓,载荷脉冲时间增长,而两种试件的载荷平台段幅值相当。根据实验和数值模拟结果,进一步分析了霍普金森杆测试Taylor撞击载荷历程的适用性。     

带窗口磁驱动准等熵压缩实验模拟

在二维磁驱动数值模拟程序MDSC2中增加了LiF材料的材料参数和功能模块,使MDSC2程序具有了求解带窗口磁驱动准等熵压缩实验的能力。采用MDSC2程序,对大电流脉冲功率装置上的exp-3-window、exp-6-window带窗口磁驱动准等熵压缩实验进行了模拟。数值模拟结果表明,二维磁驱动数值模拟程序MDSC2能正确模拟带窗口磁驱动准等熵压缩实验exp-3-window和exp-6-window的全过程,模拟的飞片/窗口界面速度在飞片/窗口界面速度的上升阶段、峰值附近和卸载阶段与实验测量基本一致,验证了新程序的计算有效性。MDSC2程序对带窗口磁驱动准等熵压缩实验的正确模拟有助于磁驱动样品物性实验的研究。     

严重段塞流现象与立管顶部节流的瞬态模拟

在对严重段塞流现象实验研究的基础上,本文采用OLGA软件建立了实验系统的瞬态模型,对水平段长度为114 m,下倾段长度为133 m,立管高度为15.3 m,内径为50.8 mm的集输-立管系统中的严重段塞流现象进行了数值研究,给出了相应流型图,并将立管底部压力、立管顶部持液率、段塞周期等严重段塞流特性参数的模拟结果与实验结果进行了对比;本文还对控制严重段塞流现象的立管顶部节流法进行了模拟研究,并与实验结果进行了对比。研究发现,本文的瞬态模型能够较好地模拟出实验中发现的四类流型,但对严重段塞流详细特性参数的模拟不够准确,对顶部节流的模拟与实验结果相差较大,对顶部节流法消除严重段塞流的机理仍需进一步研究。     

在役枞树型叶根原位相控阵超声检测技术*

本文是利用相控阵超声检测成像技术对枞树型叶根进行全覆盖检测系列文章的第二篇。根据检测工艺制作人工缺陷参考试块对叶根不同区域缺陷的检测覆盖和检测灵敏度进行验证研究,并与CIVA模拟缺陷信号结果进行对比。首先采用文章Ⅰ得出的全覆盖检测工艺进行相控阵超声检测实验,针对叶根检测空间受限设计了夹具对探头进行控制,保证了耦合与检测结果的重复性,实现叶根检测数据与检测位置的对应。检测结果表明：(1)叶根内、外弧缺陷相控阵检测数据成像与Civa仿真缺陷模拟检测结果基本一致,说明利用三维扫描尺寸建模和声学仿真模拟软件可有效解决不同规格枞树型叶根全覆盖检测工艺开发难题;(2)根据相控阵检测数据S视图和A视图,结合叶根截面外形结构图可有效判别叶根各截面第1齿根处的缺陷,实现了叶根相控阵全覆盖检测;(3)按照该相控阵组合检测工艺检测出的缺陷信号信噪比高,定位精准,能有效实现在役叶根原位检测。研究结果对相控阵超声技术在汽轮机叶根在役检测工程应用具有较大的参考价值。     

温室及其蓄热层中传热与流动的研究

针对被动式太阳能温室系统,分析了玻璃顶部覆盖面倾角不同,对温室中温度及气流分布的影响。温室玻璃顶部覆盖面倾角,可以改变温室中的气流、温度分布。研究了温室蓄热层传热与流动。温室中土壤或岩床具有吸收并贮存太阳能的作用。     

Effect of Orientation of Ice Crystals in Cirrus on Direct and Scattered Solar Radiation Fluxes

Russian Physics Journal - The problem of solar radiation transfer by cirrus containing horizontally oriented ice crystals urgent today is considered. The results of a complex radiation experiment...     

温室内多孔蓄热墙传热与流动特性

本文采用一维稳态饱和多孔介质能量双方程模型,对温室内多孔蓄热墙的传热与流动特性进行了研究.结果表明:多孔蓄热墙的固体骨架与空气之间的换热取决于空气的入口流速、多孔材料的孔隙率、渗透率和固体骨架的导热系数,由于多孔蓄热墙接受的太阳辐照是不均匀的,因此推荐采用具有不同孔隙率的新型复合多孔蓄热墙,以减少这种不利的影响.     

温室内太阳净辐射量的计算方法

在现有理论及方法的基础上进行了相应推导 ,得出了进入温室内太阳净辐射量的计算方法。该计算方法可以为温室结构设计及能量计算提供理论依据。     

空间辐照环境对光学材料作用效应的模拟研究

介绍了对材料有重要影响的空间辐照环境 ,并利用地面模拟设备对某些遥感光学材料在空间辐照环境下的行为进行研究。结果表明 ,以质子、电子和太阳紫外线为代表的空间辐照环境在光学材料中产生表面剥蚀、着色、诱发表面污染和充放电等效应 ,从而使光学材料的性能在不同程度上退化     

Cosmic ray-aerosol-cloud interactions in the atmospheric environment: Theoretical aspects

The microphysical and radiative processes involved in the interaction of cosmic radiation with the aerosol particulates in the atmosphere aggravate the ion-induced formation of aerosol particles that can act as cloud condensation nuclei (CCN). This may in turn affect the cloud droplet distribution and optical properties of clouds and enhance the process of rising global temperature depending upon the microphysical mechanism. Major observational information about the abundance of aerosols in the tropical atmosphere are obtained from the Indian Ocean experiment (INDOEX) field experiments and about the solar activity and solar cycle from the satellite observations. It has been noticed that when solar activity is less, more cosmic rays pass through the atmosphere, which activate the aerosols already present in the tropical atmosphere. The fluctuations in the cosmic rays due to variations in the solar activity can produce significant changes in the atmospheric environment.     

太阳辐照对静止水面稳态蒸发的影响

针对低风速下静止水面的蒸发过程,考虑水面与气流的对流传热传质、水体对太阳能辐射的容积内光谱吸收及内部传热,建立分析太阳辐照作用的水面稳态蒸发模型.采用控制容积法结合蒙特卡洛法和谱带模型数值求解水体内部、表面、气流之间的能量传递与质交换.分析空气湿度、温度、流速及正逆温差下,太阳辐照强度对于水面蒸发的影响.结果表明,太阳辐照强度对低风速下静止水面蒸发的影响很大.     

Switching of heating and cooling modes using thermal radiation films

We study emissivity (ε)-dependent radiative heat transfer phenomena in remote and contact configurations. To demonstrate the emissivity-dependent radiative heating mode in a remote configuration, we fabricated miniature greenhouses covered with low (0.34)- and high-ε (0.86) polyethylene films and monitored temperatures on the floors, insides, and covers of the greenhouses during 24 h. The high-ε greenhouse yielded a 9-°C increase in floor temperature relative to the low-ε greenhouse at a one-sun solar irradiance because the high-ε film effectively trapped floor radiation. In contrast, the cover temperature remained lower in the high-ε greenhouse due to intensified radiation released from the high-ε film. This self-cooling effect was more evident when an emissive film was in physical contact with an object. While bare copper heated up to 55 °C, a high-ε film coated copper substrate was kept cooler by 4 and 2 °C compared with the bare and low-ε film coated copper samples, respectively.     

辐射烧蚀CH薄膜非平衡理论计算与实验比对分析

 用一维非平衡辐射输运程序和实验提供的黑腔辐射流，对CH薄膜靶的辐射烧蚀进行了数值模拟计算。计算结果表明，非平衡的黑腔辐射场对CH薄膜靶辐射烧蚀的影响十分明显。出靶外界面的辐射流总强度、等效辐射温度随时间变化、400eV光子出界面延迟时间随靶厚度变化规律等方面的数值模拟结果与实验结果基本符合。     

Assessment of integrated solar ultraviolet radiation by PM-355 detectors

The increase in environmental solar UV radiation due to depletion of ozone layer is a recent challenge to human health (skin cancer and eye effects) in countries having clear skies. Therefore, applying integrated, passive and inexpensive techniques to assess solar UV radiation is very much essential. Measurements of environmental solar UV radiation in Dhahran, Saudi Arabia area were carried out for a period of two months in the summer period in 1996 using two techniques in parallel namely: passive nuclear track detectors and active solar UV radiometers. Some of the nuclear track detectors were mounted in different conditions such as: under shadow band, on solar tracking mechanism following the solar rays. Others were mounted on perpendicular, tilted and horizontal surfaces in sunlight. All detectors were attached to a wooden background of the same thickness (0.5 cm) to eliminate interference of the heat effect of various support materials and have uniformity of the support materials. The assessment was carried out for different periods extending from two to nine weeks continuously. The investigated period covered the hottest months in Saudi Arabia (July and August) when the sky was clear of clouds. The results indicate linear correlation between alpha track diameters and the integrated exposure to solar UV as measured by the solar UV radiometer for all nuclear track detector positions and orientations. The highest slope has been observed for the detectors placed on solar tracking mechanism following the solar rays and the lowest from detectors oriented under the shadow band on horizontal position (measuring the diffused UV radiation only). The results show that most of the measured UV radiation (60%) were from the diffused UV radiation. The characteristics of the upper layer of the detectors are changed after chemical etching very quickly, with increase in the exposure time to UV solar radiation at certain orientation. The results encourage the use of nuclear track detectors for environmental and personal solar UV dosimetry on a large scale in Saudi Arabia and similar hot and clear-sky countries.