气固两相圆湍射流流动的大涡模拟

针对气固圆湍射流流动采用基于双向耦合的大涡模拟方法进行了模拟,研究了直径为105μm的颗粒的存在对圆湍射流的影响。单相流动的预报结果在射流形态以及时均速度和湍流强度等统计结果方面均与实验结果符合良好。两相流动的时均速度和湍流强度等统计结果与实验结果符合较好,与单相流动的模拟结果相比,105μm的颗粒加入流场后,由于其较快的响应特征起到了阻尼作用,从而降低了气相场的湍流强度。     

大曲率结构化表面湍流流场特性对比研究

湍流模型选择对于小尺寸大曲率圆管内软性磨粒流湍流流场模拟计算具有重要影响.针对此问题,提出使用标准k-ε模型与考虑两相磨粒流平均流动中的旋转及旋流流动情况的重整化群(RNG)k-ε模型进行仿真对比研究的方法.基于颗粒动力学理论的欧拉模型,对软性磨粒流的控制方程进行求解.通过使用两种湍流模型,对小尺寸大曲率圆管内湍流流动进行仿真计算,得到了两湍流模型下软性磨粒流流场的速度、压力、湍动能等数值模拟结果.仿真结果对比分析表明:标准k-ε模型模拟得到的速度值与实验值存在一定误差,而RNG k-ε模型仿真的速度值误差相对较小;标准k-ε模型对湍动能的估值计算比RNG k-ε湍流模型高,难以计算有滞止点的流动过程;RNG k-ε湍流模型能更有效地模拟有大曲率带分离的湍流流动,从而证明该模型更适合小尺寸大曲率圆管内软性磨粒流湍流流动的研究.     

不同材料颗粒对两相湍射流场的调制规律

为探讨不同材料颗粒对气相湍流场的影响,该文采用三维颗粒动态分析仪设备测量了气固两相圆湍射流中x<25d范围内两相流中气相湍流度的分布。比较了加入250μm和75μm的玻璃微珠和铜粉颗粒产生的影响。结果显示,相同粒径的颗粒,在喷口附近区域,玻璃微珠对气相湍流度的增强作用高于铜粉;在远离喷口区域,玻璃微珠颗粒对气相湍流度的削弱作用小于铜粉颗粒。相同材料的颗粒,粒径越小对气相湍流度的削弱作用越强。     

不同材料颗粒对两相湍射流场的调制规律

为探讨不同材料颗粒对气相湍流场的影响,该文采用三维颗粒动态分析仪设备测量了气固两相圆湍射流中x<25d范围内两相流中气相湍流度的分布,比较了加入250μm和75μm的玻璃微珠和铜粉颗粒产生的影响。结果显示:相同粒径的颗粒,在喷口附近区域,玻璃微珠对气相湍流度的增强作用高于铜粉;在远离喷口区域,玻璃微珠颗粒对气相湍流度的削弱作用小于铜粉颗粒。相同材料的颗粒,粒径越小对气相湍流度的削弱作用越强。     

颗粒在气固两相圆湍射流近场截面对气相的影响

为探讨气固两相射流中不同粒径颗粒对气相的作用,用激光粒子动态分析仪(PDA)测量气固两相圆湍射流中X/D=5截面上的气相流动参数,并与相同出口速度的单相射流做比较。喷口直径为20mm,气相出口Re=13600。采用了从50μm到300μm之间6种不同平均粒径的玻璃微珠作为颗粒相。结果表明:粒径较小的粒子对气相轴向时均速度沿径向衰减的延迟作用较强,对气相轴向和径向湍流度的削弱幅度较大。粒径较大的粒子能增强轴心附近气相轴向湍流度。     

泄洪洞出口扭曲斜切挑坎挑流数值模拟

采用RNGκ-ε湍流模型与VOF多相模型对扭曲斜切型挑坎进行水气两相流三维数值模拟,模拟了挑流水舌的空中形态,水舌挑距,水舌挑高,以及水舌速度分布、湍动能k与湍动能耗散率ε的分布情况.数值模拟成果与模型试验观测数据吻合良好,验证了该数值模拟方法的可靠性和合理性,可以为工程优化设计提供科学依据.     

突扩两相流动中颗粒相对气体湍流的影响

为了研究颗粒相的存在对气体湍流的影响,用相位Doppler激光测速仪(phase Doppler particle anemometer, PDPA)测量了竖直轴对称突扩通道中两相流动中的气体湍流变动,给出单相流动和气粒两相流动时的平均速度和轴向脉动速度,阐明了颗粒对气体湍流的作用,即湍流变动规律.结果表明,平均粒径150 μm的颗粒在流场的不同位置造成的湍流变动现象有所不同.在回流区内,靠近轴线附近的正流区内颗粒增强了气体湍流; 在逆流区以及下游区域,颗粒削弱了气体湍流.     

用扩散流模型数值模拟后台阶湍流颗粒输运

建立了一个两维气固两相湍流扩散流数学模型,并且用此模型数值模拟了气固两相绕流后台阶的湍流流动.预测分析了台阶后固体颗粒的湍流输运速度,并将预测结果与Laslandes等的用两种两流体模型(k-ε-A p ,k-ε-k p )的数值预测结果及实验结果进行了比对,结果表明扩散流数学模型可以用于描述气固两相流动.它的预测效果不但与目前实用的两流体模型相当,而且还可以正确地预测固体颗粒的横向速度,在这一点上还超过了两流体模型的预测效果.     

多股流喷吹粉煤时高炉风口内粉煤浓度场分布

为了揭示改型前、后2种喷煤枪喷吹粉煤气-粒两相湍流流动过程的浓度场的分布,根据质量守恒、动量守恒、混合组分平衡的基本规律建立了高炉粉煤喷吹三维气-粒两相湍流流动过程数学模型,采用k-ε方程描述风口内气-粒两相的湍流流动,通过对Euler正交坐标下节点离散化方程的耦合关系分析求解,采有3组粒度不同的粉煤颗粒对喷枪改型前、后高炉风口湍流流动进行数值计算.计算结果表明随着粉煤颗粒粒度的增加,多股流喷枪对风口底面的低浓度特性明显,当粒度为100 μm时,喷枪对风口底面的浓度为单股流时浓度的(1)/(20);当粒度为75 μm时,为(1)/(10),当粒度为50 μm时,为(1)/(5),这与实验结果相吻合.     

底吹气体搅拌下熔池内流场的研究

本文将物理模型实验与数学模型数值求解相配合,对底吹气体揽拌下熔池内流场进行了研究。以湍流运动学方程和动力学方程、Harlow—Nakayama湍流k—ε双方程模型[1]及边界条件构成了所研究问题的数学模型,应用Spalding等计算湍流回流的方法[2],对数学模型数值求解,得到熔池流场涡量,流函数、湍动能、湍动能耗散率、湍流旋涡粘性系数、速度、含气率及密度等的分布,计算与测定了三种工况,计算与实验结果吻合。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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