开缝V形火焰稳定器的冷态实验研究

提出了一种新型加力燃烧室稳定器——中心开缝的V形钝体．在开式风洞中,对两种不同形状的新型V形稳定器在不同缝宽下的阻力特性和尾迹结构进行了实验研究．对比分析表明：流线型稳定器的阻力特性优于非流线型稳定器,但反流区大小却小于后者．     

低雷诺数开缝圆柱绕流尾迹流场特性

为了揭示开缝对圆柱尾迹流场的影响,采用数值模拟方法对低雷诺数无限大流场中开缝圆柱绕流进行研究,以相对缝宽(即缝宽/圆柱直径)和开缝角为变量,斯特劳哈尔数、阻力系数和升力系数为特征参数,分析不同开缝条件下旋涡脱落和圆柱受力的演化过程。研究结果表明:圆周压力分布受相对缝宽和开缝角的影响较小,圆周压力最小点位置随相对缝宽和开缝角的增大而后移;当相对缝宽为0.1时,最大后移幅度为6.11°;边界层分离点随开缝角增大而后移,而边界层分离点随相对缝宽的变化则因开缝角范围不同而不同;随着开缝角增大,开缝圆柱所受阻力减小,当相对缝宽为0.1、开缝角为90°时,可减阻14.63%,升力先增加后减小,旋涡脱落频率增大。     

单角煤粉燃烧炉中煤粉着火与稳燃的数值模拟

在自行建立的数学模型基础上，对单角煤粉燃烧炉中煤粉着火与火焰稳定性进行了详尽的数值模拟。给出了直流式燃烧器、钝体燃烧铭及开缝钝体燃烧器的数值模拟结果，得到了与实验一致的结论，还针对直流式燃烧器考察了影响煤粉着火与火焰稳定性的各个因素。     

钝体及开缝钝体燃烧器火焰稳定性对比分析

基于回流区中煤粉挥发分释热点燃主气流实现火焰稳定的集总分析模型，导出使煤粉气流火焰稳定的最小口流区长度、最大允许的主气流流速及极限最大可用挥发分释热量的表达式，并以此为准则对钝体及开缝钝体燃烧器的火焰稳定性能进行了对比分析．研究表明，在相同条件下开缝钝体燃烧器有优于钝体的火焰稳定性能．同时在通道流场燃烧器上对几种煤粉进行了两种燃烧器的燃烧性能实验，其结果与理论分析一致．     

钝体冷态流场的PIV实验研究

运用PIV技术在风洞中分别对5种不同形式的钝体：标准钝体、三角形钝体、流线形钝体、带通道钝体及非流线形钝体在冷态工作环境、不同缝宽下,获取了钝体后的速度分布.对比了5种不同钝体在不同缝宽下回流区长度的变化,认为随开度增大,在回流区结构不遭到破坏的前提下,回流区长度加大.同等条件下,非流线形钝体有最大的回流区长度;通过对尾迹区域的平均湍流动能的分析,认为平均湍流动能的强度随缝开度加大开始减弱,湍流强度最大的区域逐渐后移,最终往回流区的上下边界发展.通过对钝体后的尾迹结构和流动特性进行分析,为热态实验奠定了基础.     

钝化及开缝钝体燃烧器火焰稳定性对比分析

基于回流区中煤粉挥发分释热点煤燃主气流实现火焰稳定的集总分析模型，导出使煤粉气流火珠最小回流区长度、最大允许的主气流流速及极限最大可用挥发分释热量的表达式，并以此为准则对钝体及开缝钝化燃烧器的火焰稳定性能进行了对比分析，研究表明，在相同条件下开缝钝体燃烧器有优于钝体的火焰稳定性能，同时在通道流场燃烧器上对几种煤粉进行了两种燃烧器的烧性能实验，其结果与理论分析一致。     

多孔介质钝体火焰稳定特性实验研究

提出采用多孔介质材料制作火焰稳定器,利用其通透和弥散性能改善钝体后燃空比,降低钝体引起的压力损失,提高火焰稳定性.通过实心钝体、10和40PPI(pores per inch)多孔介质钝体火焰稳定特性和冷态尾迹测量对比实验发现:多孔介质火焰稳定器可获得更宽的火焰稳定范围;相同燃料和空气伴流条件下,多孔介质钝体后火焰刚性更强,燃烧更充分;实心钝体回流区较靠近钝体,回流区强度较强;多孔介质钝体回流区向下游发展,回流区强度较弱,但空气燃料混合更好.因此多孔介质稳定器关键是要确定合适的孔径,使火焰更稳定燃烧.     

小尺寸扰动体对双钝体系统动力学特性及传热的影响

基于Fluent流场分析软件,通过有限体积法数值研究雷诺数Re=200,钝体间距比L/D=5时,钝体直径比(d/D=1、0.5、0.25)和双钝体距通道下壁面的间隙H(H=6D、5D、4D、3D、2D)对矩形通道双钝体系统换热性能和系统平均阻力的影响规律.研究结果表明:直径比减小,系统平均阻力较等直径双圆柱小,但系统换热性能变化不大;双钝体向下壁面靠近时,系统平均阻力和换热性能增大,但两者变化均不大.以等直径双钝体(d/D=1)位于矩形通道的中间位置(H=6D)为基准,双钝体直径比和双钝体距离下壁面的高度H改变时,系统的平均阻力ΔC_(DS)减小25.0%~43.7%,系统的换热改变量Δh为-1.81%~1.69%.     

近地鱼形钝体气动阻力特性研究

采用数值模拟与风洞试验两种方法,研究以粒突箱鲀为仿生原型的近地鱼形钝体气动阻力特性.结果表明,近地鱼形钝体确为气动低阻形体,其尾部大收缩角的形态特征及尾迹区相对简单的流场结构共同决定了该形体的气动低阻特性;从气动阻力系数、表面压力系数及尾迹区流场结构三方面对比分析,SST湍流模型的预测值与试验值较为接近.     

钝体尾迹煤粉火焰特性的研究

本文着重研究了钝体尾迹中煤粉火焰的温度分布、着火的物理模型以及煤粉的燃尽特性.研究结果表明:在电站锅炉中采用钝体燃烧器能够收到明显的节能效果.     

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