球形容器泄爆收容的实验分析

为研究气体爆炸泄爆收容过程中爆炸容器和收容容器内的压力变化规律及其影响因素,对球形容器在不同收容容器和爆炸容器体积比以及不同导管长度条件下的泄爆收容过程经行了实验研究。结果表明：收容容器体积越大,爆炸容器的压力峰值越小,爆炸压力下降的速度越快;收容容器的体积达到或超过爆炸容器体积的5倍时,接近敞开泄爆的压力峰值;泄爆导管的长度越长,爆炸容器的压力峰值越小;收容泄爆时,火焰的传播速率随着导管传播距离增加而降低,泄爆口处火焰传播速率最高。     

连通容器泄爆过程的CFD模拟

利用Fluent软件对连通容器泄爆过程中的气体爆炸流场进行数值模拟,获得气体爆炸过程的温度场和压力场,模拟结果能较清晰地反映泄爆过程。研究表明:连通容器泄爆时起爆容器的火焰高度均高于传爆容器,容器内温度随着泄爆时间的延长逐渐上升,泄爆口开启后又迅速下降;在泄爆初期,起爆容器的压力均低于传爆容器的压力,小球内压力衰减速度大于大球内压力衰减速度。     

泄爆外部压力变化特性的影响因素

为了研究可燃性气体爆炸泄爆过程中,不同因素对容器外部压力变化特性的影响,利用0.022和0.113 m3 2个球形容器进行了一系列实验。实验结果给出了不同容器容积、泄爆面积、容器结构和形式条件下容器外部压力发展历史：容器容积减小,会导致泄爆容器外部的峰值压力增大,压力变化更为迅速,持续冲击时间减小;泄爆口直径在0~0.04 m范围内增加,容器外部最大压力上升速率及峰值压力均相应增大,呈现上升的趋势但非线性,存在一个增加程度先减小后增大的驻点;容器结构和形式对泄爆过程产生显著的影响,相对于单个容器,连通容器外部峰值压力、最大压力上升速率均有较大提高;连通容器泄爆时,跟大容器泄爆相比,小容积泄爆外部最大峰值压力较大,最大压力上升速率较小。     

容器内气体爆炸带导管泄爆的实验研究

利用1个球形容器和3节相同尺寸的圆形管道建立了实验系统,并开展相关实验,研究容器内气体爆炸带导管泄爆过程的机制。结果表明:安装泄爆导管增加了容器爆炸强度;破膜激波使导管入口处压力上升,射流火焰点燃导管入口处未燃气体产生二次爆炸,导致容器内及导管入口处压力突变;一定范围内,导管长度越长,容器及管道内的压力峰值越大;有导管存在时,尾部点火容器内的压力峰值及导管入口处的压力峰值都高于中心点火的情况,且尾部点火导管前部分的火焰传播速率高于中心点火的情况;无论尾部点火还是中心点火导管入口处的压力峰值都高于导管出口处的压力峰值。     

球形容器在弯管条件下的泄爆收容

为了考察弯管对泄爆收容过程的影响,采用实验和数值模拟相结合的方法,对球形容器内可燃气体爆炸通过不同角度弯管泄放到另一球形容器的泄爆收容过程进行了研究。结果表明:泄爆收容时,由于高速气流和喷射火焰的作用,大部分进入导管内的未燃气体发生湍流燃烧,部分未燃气体随压力波到达收容容器内;泄爆收容过程中,起爆容器内压力受弯管角度的影响不大,而收容容器内压力随着弯管角度的增加不断下降。当采用90°弯管时,收容容器内的压力峰值最小为0.432 MPa。     

丝网结构对容器管道开口系统气体爆炸的影响

为研究丝网结构对容器管道开口系统气体爆炸的影响,通过改变丝网结构的层数和目数,对连接有一段管道的球形容器进行实验。研究发现,当系统处于开口状态时,在管道处加入具有抑爆效果的丝网后,容器内最大泄爆压力增大,且最大泄爆压力随着丝网层数以及丝网目数的增加而增大。建立数学模型对容器内部最大泄爆压力进行拟合,通过拟合公式发现,丝网层数对容器管道开口系统气体爆炸时的最大泄爆压力有一定的影响,并且开始时最大泄爆压力随着丝网层数的增加而增加,随后丝网结构对最大泄爆压力的影响逐渐减小,最大泄爆压力趋于稳定。     

管道障碍物对连通容器内气体爆炸的影响

对管道内存在障碍物时的连通容器气体爆炸进行研究,与管道内没有障碍物时的情况进行对比,考察管道内障碍物的位置和内径对连通容器压力变化的影响,分析不同条件下连通容器内气体爆炸的压力变化规律。结果表明:管道内障碍物加速了连通容器内气体反应的进行,且随着管道障碍物内径的变大,传爆容器的燃爆压力峰值先变大后变小;改变障碍物的位置,障碍物离起爆容器越近,传爆容器越早到达燃爆压力峰值。传爆容器内气体爆炸产生的压力波在管道内经过障碍物时,压力波有一定程度的削弱。障碍物在连通容器爆炸过程中起的主要作用:增加气体扰动,增强湍流强度,从而加速反应;阻碍压力波传播,削弱压力波强度。     

球形容器泄爆过程影响因素的数值模拟

为了研究球形容器内气体泄爆过程的影响因素及压力传播的基本规律,从能量守恒方程、质量守恒方程、动量守恒方程及化学组分平衡方程出发,建立了泄爆的数学模型,采用k-ε湍流模型和涡耗散概念模型即EDC燃烧模型,利用Fluent软件对该过程进行数值模拟,得到泄爆过程中不同时刻监测点的压力。用响应面曲线的方法讨论泄孔比、泄爆压力、容器体积对球形容器泄爆过程的影响,结果表明:泄孔比越大,危险系数越大;破膜压力过大或过小都将增大危险性;容器体积越大,越容易产生危险。因此,实际球形容器防爆泄压中,合理控制泄爆孔径、破膜压力和容器体积将对泄爆过程中产生的影响及泄爆效果至关重要。     

球形容器泄爆及其外部伤害效应

为了研究球形容器泄爆及其外部伤害效应,利用小球容器和大球容器建立了2种尺寸的球形容器泄爆测试系统。在研究球形容器泄爆内部压力变化特性时,利用大、小球容器分别开展了无膜泄爆和泄爆片泄爆2种实验,得到了如下结论:当大、小球容器泄爆时,随着泄爆口直径的增加,最大泄爆压力减小,压力上升速率减小,正压持续时间减小;当无量纲化泄压比较小时,无膜泄爆峰值压力随泄压比的增大而减小,且呈线性变化。在研究球形容器泄爆外部伤害效应时,分别进行了大、小球容器压力伤害范围实验,获取了大、小球容器泄爆口周围空间不同位置处的压力峰值,并结合超压伤害阈值标准,判断其对人员的伤害作用,从而划定了压力伤害的范围。     

采用泄爆管泄放气体爆炸的数值模拟

采用k-ε湍流模型和涡耗散概念模型（EDC）,建立泄爆管泄放气体爆炸的模型,并模拟泄爆过程中火焰的传播过程。分析点火位置、泄爆压力（Pv）、泄爆管尺寸和结构对容器内爆炸超压(P_red)和压力上升速率的影响。结果表明:泄爆管内的气体爆炸是导致P_red异常上升的原因;P_red与Pv存在线性递增关系;泄爆管管长的增大或管径的减小均会增大P_red,且管径对其的影响更显著;泄爆管与容器之间采用平滑过渡的方式可降低P_red,但增大平滑过渡半径会使P_red上升;总泄爆面积相同时,采用2根泄爆管可降低P_red,但两管的位置对P_red的影响不显著。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has