变截面烟道内导流板与布风板对再热器入口流场影响

为了分析导流板和布风板对变截面烟道内再热器入口速度分布均匀性的影响,基于N-S方程,首先对无导流板和布风板的原始烟道进行了三维流热耦合数值模拟研究;然后与仅安装导流板和同时安装导流板与布风板的烟道模型计算结果进行了对比。得到了三种不同结构条件下扩张段内流场,以及再热器入口截面速度场标准偏差系数的对比结果与变化规律。结果表明:(1)在无导流板和布风板的原始烟道中,烟气在扩张段内的速度分布极其紊乱,进而造成再热器入口速度分布极不均匀;(2)导流板的安装有利于提高再热器入口速度分布的均匀性,相对于无导流板和布风板的再热器入口截面的标准偏差系数C_v降低了15%;(3)布风板的安装不仅能够提高再热器入口速度分布的均匀性,而且能够改善布风板上游扩张段内部速度的分布情况,标准偏差系数C_v与无导流板和布风板的烟道流场结果相比降低了30.3%。     

基于流场诊断的燃煤电站SCR系统喷氨优化及试验验证

为实现SCR系统的安全高效运行,采用CFD数值模拟技术开展660 MW燃煤电站SCR系统流场优化.根据喷氨格栅前烟气流动特性解析喷氨支管阀门权重,基于权重阀开展喷氨优化研究.分析了优化前后首层催化剂入口截面烟气速度/浓度分布特性,搭建冷态模化试验装置对数值模拟研究结果进行验证.研究结果表明:导流板合理优化布置可有效改善流场分布的均匀性,速度标准偏差可相对减少约71.30%;基于权重阀优化喷氨使喷氨特性与烟气流动特性匹配良好,改善了浓度分布的均匀性,浓度标准偏差相对减少约24.95%;冷态模化试验值与数值模拟值吻合良好,两者偏差仅为3.08%;流场/权重阀喷氨优化协同作用能够最大限度提升燃煤电站SCR系统的工作性能.     

燃煤电站SCR系统气固流动与催化剂磨损的混合数值模拟与优化

以某660 MW燃煤锅炉SCR脱硝系统为对象,建立了电站实际烟气环境下的催化剂磨损评估模型.首先,利用计算流体力学软件(CFD)搭建SCR反应器模型,计算反应器内气流分布及飞灰颗粒轨迹.在此基础上,采用MATLAB软件构建催化剂床层内部详细结构,并以CFD模型计算的流场及灰场为边界条件,计算空间不同区域催化剂的磨损速率.模拟结果与冷态试验及磨损抽检试验结果吻合良好.结果表明,催化剂的磨损与入口流场均呈现双峰分布,割除整流器上方三角筋能使催化剂入口速度标准偏差从23. 2%下降至10. 2%,使磨损双峰大幅降低;改造转角烟道导流板能降低贴墙气流的速度,提高颗粒分散度,使催化剂入口飞灰浓度的标准偏差从63. 4%降至55. 6%,消除了前墙附近催化剂磨损过重的现象.     

新型电厂烟道弯头的设计及数值模拟

目前燃煤电厂烟风道设计主要依据设计规程,缺少对烟道体内流动情况的细化分析及优化设计,同时也欠缺对烟道内撑结构的考虑.本文利用计算流体动力学软件Fluent对烟道常见弯头添加常规导流板进行数值模拟,在分析讨论内撑结构及导流板对烟道内部造成影响的基础上,对原管道进行优化改造,使得出口烟气走向更加均匀,压力损失与原模型相比减小40.85%.本设计可为新型导流装置的设计提供可靠建议,有利于电厂的节能减排.     

选择性催化还原烟气脱硝系统冷模实验研究

以某电厂2×300MW燃煤机组选择性催化还原（SCR）烟气脱硝系统为研究对象建立了冷态实验模型,考察了导流板、喷氨格栅（AIG）及静态混合器对系统内速度场和浓度场的影响。实验结果表明：烟道内导流板的加入对系统内速度、浓度均匀性具有明显的改善作用,保证了反应器内速度分布变异系数（CV）低于15%、浓度分布CV低于10%;静态混合器的加入能进一步改善系统内的速度、浓度均匀性;新开发的三角形排布AIG比矩形排布AIG性能略优,而新开发的三角翼式静态混合器的混合效果明显优于传统圆管式静态混合器。     

90°方截面弯管内加装导流板的优化研究

许多工程中的弯管都存在严重的磨损和积灰问题,流场分布不均是主要原因之一.应用计算流体力学软件Phoenics对90°方截面弯管内气固两相流进行了数值模拟.模拟采用κ-ε双方程模型和IPSA两相流模型,以速度、压强等参数的流场分布图形方式输出模拟结果,分析了弯管内气固两相流流场的分布规律.弯管内不加导流板时,流场分布不均匀.在弯管中加装导流板具有均匀流场的作用,为管道磨损和积灰问题的解决提供了一条有效的途径.通过模拟分析得到了在弯管内加装导流板的最佳条件:导流板数量为3块,板的圆心角为70°,内侧板和中间板的起始位置为10°、外侧板的起始位置为0°,板间距内外两侧小、中间大.     

基于离散相的选择性催化还原脱硝装置流场优化模拟

国内某660 MW超临界机组SCR脱硝装置在实际运行中出现催化剂磨损,为解决该问题以保证脱硝效率不受影响,利用数值模拟软件FLUENT模拟研究了原始脱硝装置内的流场分布情况。通过分析结果得出影响催化剂磨损的因素,并且经过多次模拟试验提出了优化方案,并对优化方案实施后的现场进行了测试。结果表明：通过将反应器上方方形顶部改为楔形顶、适当增减导流板数量以及改变导流板间距可以大大优化烟气速度场以及飞灰颗粒浓度场,从而可以在很大程度上提高SCR脱硝系统的效率。     

镁砂煅烧窑烟气脱硝SCR法的应用与流场分析

介绍了菱镁石煅烧窑烟气的特点和危害以及SCR脱硝方法的原理与工艺流程,并且利用Fluent软件,采用标准湍流模型和多孔介质模型对SCR反应器的流场进行了数值模拟,此反应器是以某厂菱镁石高温煅烧窑烟气为对象,通过数值模拟来寻求优化设计.数值模拟结果表明,在SCR反应器内加装整流器对流场略有改善,且整流器格子大小对流场影响不大.模拟结果还得出导流板的最佳结构和位置,可以达到良好的脱硝效果.     

旋风分离器排气管内气相流场的数值模拟

采用雷诺应力模型对直切式旋风分离器内气相流动的三维流场进行数值模拟,分析了排气管内的气相流场特点及排气管直径对气相流场的影响.结果表明:排气管内气流旋转强度较高,轴向速度呈强剪切流特征,并且存在回流区,这些都是造成能量损失的重要原因;减小排气管直径可以抑制短路流量,使旋风分离器整个空间内的切向速度增大,有利于颗粒分离,但同时压降增大.     

渐变截面型入料口夹角对旋流器流场及压降的影响

利用RSM雷诺应力模型和VOF多相流模型,通过数值试验方法考察了渐变截面型入料口夹角对Φ50 mm水力旋流器流场及压降的影响.结果表明,增大入料口夹角,切向速度增加,致使分离效率提高;与此同时,轴向速度和溢流管底端的最大径向速度也随之相应增加,导致沉砂分流比略有降低、短路流量增加,但对湍流结构影响不明显;空气柱直径同样随着夹角的增加而增大,从而有效分选空间减小.旋流器内部的压力损失主要包括主分离区域的损失和入料口区域的损失;增大入料口夹角,总压降增加,导流能力增强,当夹角为20°时,导流性能最优,但能量利用率降低.     

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