转子转速和气体流量对2524铝合金除气效果的影响

采用水模拟实验和铝熔体除气实验相结合的方法研究了转子转速和惰性气体流量对旋转除气法除气效果的影响及其机理.研究结果表明转子转速和气体流量对除气效果具有重要的影响.随着转子转速的增加,气泡尺寸减小,作用的区域增加,除气速率提高.在一定范围内随着气体流量的增加,气泡数量增加,除气效率提高.但当气体流量过高时,气体在转子与熔体之间产生隔离作用,气泡影响区域减小,除气效果变差.在本研究范围内转速550~690 r/min,惰性气体流量1~3 L/min是合适的工艺参数.     

高精度（10^-15）可搬运铷原子喷泉钟的研制

原子喷泉钟是目前世界上最准的运行原子钟,主要包括铯喷泉钟和铷喷泉钟两种.中国科学院上海光学精密机械研究所于2003年开始开展了可搬运小型喷泉铷钟样机的研制,它的主要特点是：以铷原子做工作介质、损耗低、信噪比高、冷原子碰撞频移低;通过折叠光路设计,其对激光的功率要求降低2/3,系统更加紧凑稳定,更加有利于喷泉钟的工程化.该原子钟已经获得了微波跃迁的Ramsey干涉条纹,其信噪比约100,并实现了闭环锁定,1s的稳定度为8×10？13,4×104s稳定度优于6×10？15.目前正在进行误差的评估工作及系统的改进,近期将进行项目验收,预期总的频率不确定度优于4×10？15.     

Transition of Mount Etna lavas from a mantle-plume to an island-arc magmatic source

Mount Etna lies near the boundary between two regions that exhibit significantly different types of volcanism. To the north, volcanism in the Aeolian island arc is thought to be related to subduction of the Ionian lithosphere. On Sicily itself, however, no chemical or seismological evidence of subduction-related volcanism exists, and so it is thought that the volcanism-including that on Mount Etna itself-stems from the upwelling of mantle material, associated with various surface tectonic processes. But the paucity of geological evidence regarding the primary composition of magma from Mount Etna means that its source characteristics remain controversial. Here we characterize the trace-element composition of a series of lavas emitted by Mount Etna over the past 500 kyr and preserved as melt inclusions inside olivine phenocrysts. We show that the compositional change in primary magmas from Mount Etna reflects a progressive transition from a predominantly mantle-plume source to one with a greater contribution from island-arc (subduction-related) basalts. We suggest that this is associated with southward migration of the Ionian slab, which is becoming juxtaposed with a mantle plume beneath Sicily. This implies that the volcanism of Mount Etna has become more calc-alkaline, and hence more explosive, during its evolution.     

Diffuse volcanic emissions of carbon dioxide from Vulcano Island, Italy

RECENT investigations on Mount Etna (Sicily)(1-3) have revealed that volcanoes may release abundant carbon dioxide not only from their active craters, but also from their flanks, as diffuse soil emanations. Here we present analyses of soil gases and air in water wells on Vulcano Island which provide further evidence of such lateral degassing. Nearly pure carbon dioxide, enriched in helium and radon, escapes from the slopes of the Fossa active cone, adding a total output of 30 tonnes per day to the fumarolic crater discharge ( 180 tonnes CO(2) per day). This emanation has similar He/CO(2) and (13)C/(12)C ratios to those of the crater fumaroles (300%ndash;500 degrees C) and therefore a similar volcanic origin. Gases rich in carbon dioxide also escape at sea level along the isthmus between the Fossa and Vulcanello volcanic cones, but their depletion in both He and (13)C suggests a distinct source. Diffuse volcanic gas emanations, once their genetic link with central fumarole degassing has been demonstrated, can be used for continuous volcano monitoring, at safe distances from active craters. Such monitoring has been initiated at Vulcano, where soil and well emanations of nearly pure CO(2) themselves represent a threat to the local population.     

Redox evolution of a degassing magma rising to the surface

Volatiles carried by magmas, either dissolved or exsolved, have a fundamental effect on a variety of geological phenomena, such as magma dynamics and the composition of the Earth's atmosphere. In particular, the redox state of volcanic gases emanating at the Earth's surface is widely believed to mirror that of the magma source, and is thought to have exerted a first-order control on the secular evolution of atmospheric oxygen. Oxygen fugacity (f(O2) estimated from lava or related gas chemistry, however, may vary by as much as one log unit, and the reason for such differences remains obscure. Here we use a coupled chemical-physical model of conduit flow to show that the redox state evolution of an ascending magma, and thus of its coexisting gas phase, is strongly dependent on both the composition and the amount of gas in the reservoir. Magmas with no sulphur show a systematic f(O2) increase during ascent, by as much as 2 log units. Magmas with sulphur show also a change of redox state during ascent, but the direction of change depends on the initial f(O2) in the reservoir. Our calculations closely reproduce the H2S/SO2 ratios of volcanic gases observed at convergent settings, yet the difference between f(O2) in the reservoir and that at the exit of the volcanic conduit may be as much as 1.5 log units. Thus, the redox state of erupted magmas is not necessarily a good proxy of the redox state of the gases they emit. Our findings may require re-evaluation of models aimed at quantifying the role of magmatic volatiles in geological processes.     

压缩空气含水层储能系统设计及可行性分析

采用数值模拟方法,以3 MW储能规模为例,建立水平地层埋深800 m、渗透率0.5×10~(-12)m~2的压缩空气地下含水层储能模型,对初始气囊及系统循环过程中压力、气相饱和度、系统循环次数等参数进行分析.结果表明:经历完整一次循环后,地层中压力和气相饱和度变化较小;随着循环的继续,地层中可供储能释能循环的有效气相体积缓慢减少;周循环过程压力变化范围较大,对储能系统要求较高.含水层作为储气库进行压缩空气储能具有可行性,应根据实际地质条件进行相应系统设计.     

Periodic flow characteristics during RH vacuum circulation refining

The circulation period of RH vacuum refining was studied to promote the refining efficiency. The influences of the lift gas flow rate and submersion depth of snorkels on the circulation period, and the relationship between mixing time and circulation flow were discussed. The effects of the lift gas flow rate and submersion depth on the degassing rate in one circulation period were studied by water modeling. The results show that the circulation period is shortened by increasing the lift gas flow rate. The circulation period is the shortest when the submersion depth of snorkels is 560 mm. The whole ladle can be mixed thoroughly after three times of circulation. Increasing the lift gas flow rate can enhance the degassing rate of RH circulation.     

铝熔体高效除氢机理探讨

对铝合金熔体吹气法除氢过程动力学、除氢-吸氢的动态过程以及除氢所需的惰性气体流量进行了分析,探讨了实现高效节能的基本条件。分析结果表明,要实现高效节能除氢须满足以下几个条件:气泡的尺寸尽可能要小;净化处理时,熔体表面应覆盖熔剂或在真空下进行;应尽可能增大除氢时惰性气体的单位流量。     

巷道气体分层流特性分析

在瓦斯隧道的施工和矿井工作面的生产过程中顶板出现瓦斯层状积聚,是导致地下工程灾害的重要危险源,含有瓦斯积聚层的巷道风流属气体密度分层流,给出巷道气体分层流的数值计算模型,在与实验结果对比基础上,进行了计算机数值模拟,并分析了巷道气体分层流的特征,讨论了影响瓦斯积聚层气体速度降低,和积聚层瓦斯浓度稳定的因素。     

山西5起小煤矿瓦斯爆炸与青海8.1级地震有关吗？

地球深部活动会导致地壳变形和断裂,从而诱发地震;地球深部活动还会加剧幔源气体释放并向地表及大气圈扩散,其中包括氢气释放;自然中的煤不仅自身产生氢气,还可能捕集来自深部的氢气,并在开采过程中释放,从而可能出现氢气诱发的煤矿瓦斯爆炸。2001年11月13日至22日,山西阳泉等地点相继发生了5起煤矿瓦斯爆炸及多次余爆事件;11月14日17时26分,在昆仑山区域发生了里氏8.1级强地震,直至11月23日相继发生多起5级以上的余震。这样巧合的看似独立的事件是否通过氢气释放活动而存在某种内在的必然联系,应成为科学家共同关心的课题。     

基于OGRE粒子系统的喷泉模拟

粒子系统在计算机图形学中占有至关重要的地位,被用于实时模拟自然景物和现象中.在粒子系统的基本理论结构上研究了面向对象的图形渲染引擎（OGRE）粒子系统的核心原理以及粒子脚本语言.提出了一种基于OGRE粒子系统的喷泉模拟方法,在该图形渲染引擎下实现了多种喷泉效果.使用这种简本语言使程序员更容易开发,大大提高了喷泉模拟的开发速度和开发效率.     

脱气对致密油藏流体渗流规律影响研究进展

 致密油藏大多含有溶解气，开采压力低于泡点压力时溶解气析出，产生渗流阻力，影响产能。从致密储层孔喉结构特征入手，阐述了脱气后致密油藏流体渗流特征形成的内因，分析了油藏脱气后流体的流动特征和影响因素，对比了致密油藏和常规油藏在脱气后流体渗流特征的差异，概述了现有的研究手段及相关数学模型的研究现状，展望了脱气后致密油藏流体渗流规律研究趋势。     

CFD优化大型浅层鼓泡塔管式气体分布器结构

分布器结构影响大型浅层鼓泡塔反应器性能,采用CFD模拟研究了5种四管气体分布器,各分布器的通气管均匀布置在不同的分布环上（0.3/0.4/0.5/0.6/0.7＊DT）,模拟采用了双流体方法和多气泡簇MUSIG模型。文中较全面的考察了高表观气速下（Ug=0.1m/s）管式分布器分布环直径对反应器流型、相含率、液速、湍b流、气泡大小以及混合时间的影响;模拟结果表明整体气含率和混合时间均随环径比先增大后减小,气含率的最佳环径比在0.4左右,而混合时间最大值出现在0.5d/DT附近,当环径比小于时0.5,鼓泡塔内为单循环流动,大于此值,鼓泡塔内将形成双循环流动,不利于混合。     

连铸结晶器内气泡群粒径分布的实验研究

为了获得结晶器内的气泡粒径及其分布规律,建立了一套水模型实验系统.为模拟真实上水口的吹氩过程,采用莫来石制作水模型的环状吹气装置,利用激光片光源和高速摄像机捕捉气泡的瞬时分布,并采用Image J软件分析和计算气泡的粒径.结果发现:气泡平均粒径随水流量、水口插入深度的增加而增大,随吹气量、水口倾角的增大而减小;莫来石弥散砖产生的气泡初始粒径较小且分布均匀.气泡粒径在结晶器宽面一侧水平方向上呈先增大后减小的趋势.随水流量的增大,气泡分布更加分散;随吹气量的增加,气泡分布规律无明显区别,但粒径增大.     

地层H2S侵入时井筒压力变化规律及控制研究

随着我国酸性油气藏勘探开发的深入,处于对井控安全的考虑,需对酸性气体侵入后井筒多相流动及相态转变规律进行研究。针对H₂S特殊的物理性质,并考虑其在井筒内相态变化,建立了钻井过程中H₂S侵入时井筒流动与传热的数学模型。将井筒传热、压力与H₂S物性参数耦合迭代计算,给出了求解方法并编写程序进行数值计算。计算结果表明:井口回压较小时,H₂S在环空上升过程中由液态转化为气态,相态转变点上部为气液两相流,其压力梯度较小,下部为井筒单相流,其压力梯度较大。H₂S侵入速度对环空压力和相变井深均有影响。随着侵入量增大,井底压力先急剧减小,后基本保持不变,而相变井深先增大后减小。井口回压对井底压力影响较大。随着井口回压增大,井底压力增大,但影响程度逐渐减小。井口回压不仅可以控制井筒是否发生相变,而且对相变井深位置影响十分大。对是否考虑传热对相变井深和井底压力的影响进行了对比分析。研究对提高酸性油气藏开发勘探安全具有一定指导意义。     

岩浆脱气动力学研究进展

岩浆脱气动力学是地球动力学的一个重要方面。介绍了H2 O和CO2 在岩浆中溶解、气泡成核、气泡生长与上升以及岩浆喷发等过程的研究成果。由前人的研究结果可知 ,压力降低使得气体在岩浆中过饱和是气泡形成的主要原因 ;气体过饱和度增大加速气体的释放和气泡的生长 ,进而导致岩浆的浮力增大 ,岩浆上升速度加快 ;气泡膨胀和加速作用发生在岩浆爆裂之前 ,并且是引起爆裂的真正原因。此外 ,CO2 的溶解度较小和岩浆中CO2 含量较高是气泡中CO2 含量高的主要原因。同时也指出 ,文献中的模型与岩浆喷发的实际情况相比 ,体系成分过于简单 ,还有待进一步完善。对岩浆脱气动力学研究作了客观评价和展望。     

Carbon dioxide degassing flux from two geothermal fields in Tibet,China

Over geological time scales,Earth degassing has a significant impact on atmospheric carbon dioxide(CO2) concentrations,which are an important component of global carbon cycle models.In Tibet,structural conditions and associated widespread geothermal systems lead to carbon dioxide degassing during geothermal water migration.We characterized the hydrochemical conditions of two geothermal fields on the Tibetan Plateau.The chemical composition of geothermal waters was controlled by K-feldspar and albite.Geother...     

连铸结晶器内气泡运动行为及影响因素

为了研究连铸结晶内气泡的运动行为及影响因素,采用了改进的数学模型对气泡在钢液内的运动行为进行了模拟.数学模型考虑气泡的弹开、聚合以及破碎行为,分析了不同拉速和浸入深度对气泡分布范围、含气率以及气泡平均直径的影响.研究结果表明:初始直径较小的氩气泡在水口内的运动过程中会发生碰撞聚合,生成大气泡.相同拉速下,气泡的分布范围和含气率随着水口浸入深度的增加而增大,气泡平均直径随浸入深度的增大而减小.相同浸入深度下,气泡的分布范围和含气率随着拉速的增加而增大,气泡平均直径随拉速的增大而减小.拉速对气泡直径的影响大于浸入深度的影响.     

180t RH气体扩散行为物理模拟

以某炼钢厂钢包和RH真空精炼设备为原型,建立与原型尺寸比为1:4的物理模型,测量吹入CO2后Na OH水溶液p H值变化来研究供氧、脱碳等气体扩散行为。通过不同提气量和真空度条件下的对比试验,可以得出:吹气过程,真空度对CO2浓度变化影响不大,提气量对CO2浓度的影响较大,增加提气量能够提高CO2浓度,提气量为5.2 m3/h时CO2浓度比提气量为3.0 m3/h时高约7%;脱气过程,真空度对CO2浓度的影响有所改善,提气量对CO2浓度的影响趋势比真空度稍微明显一些。     

气泡在垂直向上流动液体中的形成

研究了液体垂直向上流动、气体水平引入时，导管端头处形成的气泡的尺寸大小。考察了液体平均流速、气体流量和导管直径对气泡脱离尺寸大小的影响。在力平衡假设的基础上，获得了预测气泡脱离尺寸的关系式，预测值与测量值比较，结果令人满意。