挡板结构对微混合器内流动与混合的影响

对内置3种不同挡板的T型微混合器内的流动与混合进行数值模拟,比较流动与混合的发展过程,分析不同挡板结构的对流作用机理以及混合随通道长度方向的发展变化.讨论了不同雷诺数(Re)下,挡板结构对混合强度与压力损失的影响.结果表明,在5Re≤90范围内,3种挡板结构产生的混合强度与压力损失均随Re的增大而增大.矩形挡板产生的混合效果最佳,但结合压力损失评价,认为斜面梯形具备最优的综合性能.     

新型三次采油用静态混合器组合的性能研究

油田聚合物驱油过程中,油田采出水与高浓度聚合物溶液的混合过程所使用的静态混合器的混合效果很大程度上影响着采油效率.针对目前油田常用静态混合器能耗较高、混合效果不好等问题,开发了一种新型静态混合器组合.基于计算流体力学理论,通过数值模拟与实验测试研究流体在混合器内的流动情况及混合效果,并与两种工业用混合器的性能进行了对比.研究结果表明:模拟结果与实验数据拟合较好;该混合器组合能耗较低,流体流经混合器组合后浓度分布均匀,完全适用于油田聚合物驱油过程.     

Lightnin静态混合器内瞬态流场POD分析及混合特性研究

为了研究Lightnin静态混合器（LSM）内的瞬态流场结构和混合特性，以水为工质采用ANSYS FLUENT V16.1中的大涡模拟（large eddy simulation，LES）湍流模型对不同长径比和雷诺数下LSM内的湍流流动进行数值模拟，并用本征正交分解（POD）方法对流场结构进行模态分解以提取流场相干结构。结果表明：当采样数量达到2 000时，低阶模态蕴含流场主要的旋涡结构信息；混合段内横截面平均涡量分布呈正弦状周期性变化，在z/l=5.0~6.0范围内，Re=3 981、5 971和7 962时的平均涡量相较于Re=1 990时增长148.5%~322.7%，拉伸率提高11.5%~18.9%；小长径比的LSM中流体被拉伸的概率更大。     

中量真空树脂灌注机新型混合器的研究

讨论了真空树脂灌注机新型静态混合在的结构及小孔小自由射流混合机理。通过对小孔射流的动力学分析,得出了射流速度发布图并推导出混合器压力损失的数学模型。分析了流体速度和混合器单元个数对混合效果的影响,给出了混合器混合效果的评介方法,并依据此评价方法对理论分析结果和混合效果进行了实验验证,结果表明,新型静态混合器的混合效果良好。     

基于ANSYS Workbench的新型SMX静态混合器的数值分析

设计了一种新型SMX-G静态混合元件,并利用数值模拟的方法比较新型SMX-G和SMX型静态混合元件两种结构的出口平均温度、压力损失和混合效果。结合出口平均温度、压力损失及混合效果,提出了静态混合器的综合评价指标,并采用红外成像仪测温法对混合效果进行实验验证。结果表明：新型SMX-G静态混合器极大程度地减小了压力降,综合评价指标更高,保证了熔体流入机头的压力,从而显著提高了发泡制品的质量。     

三维方管中柱体可压绕流的大涡模拟

该文利用大涡模拟,对可压缩流体绕经安装在方管底部的长方体和矩形体的绕流现象进行了三维数值模拟.模拟结果显示了流体绕经障碍物后各涡的形成和耗散过程. 分析了不同Re时柱体绕流流场的结构.发现长方体壁面上的各个涡在小雷诺数时基本稳定,在大雷诺数时涡容易脱落,流场呈现复杂的湍流结构.通过改变柱体障碍物的高度,得到了绕流流场在不同阻塞比下的结构变化,发现湍流现象随着阻塞比的增大而增强.     

一种新的气体混合评价准则

气体混合的判断和衡量在理论研究和工程实际中都有着重要的应用.文章在流场浓度分布及混合理论分析的基础上,总结提出了一个新的气体混合评价准则Γ,并用大涡模拟的方法,对一系列气体混合模型及不同的入口条件进行数值模拟,在实际流场中对混合评价准则Γ的实用性及准确性进行验证.由模拟分析可得,Γ和通用的均方根准则一样可以准确地作为混合效果的最终评价准则,同时还可以较全面地反映整个流场的混合强度分布,并给出了应用实例,对混合器的评价和设计都有一定的指导意义.     

一种棋盘形分布表面电势的电渗微混合器设计

提出了一种新型的电渗微混合器设计方案.在管道的顶部和底部采用棋盘形交替分布的表面电势,当管道内施加电场,这些交替分布的表面电势会在微管道内诱导复杂的波状电渗流动,折叠(fold)和拉伸(stretch)管道内的流体,使混合效果得到增强.数值模拟结果显示该混合器的混合效果得到了很大的增强.首先通过两个三维算例的比较,验证了数值模拟的可靠性;然后基于对流场结构的分析,定性地阐述了这种微混合器增强混合的机理;同时探讨了不同参数对这种微混合器性能的影响.     

组合转子管式光生物反应器气液两相流混合特性模拟研究

通过Fluent流场分析软件对组合转子管式光生物反应器气液两相流混合特性进行模拟。以欧拉多相流模型、k-ε湍流模型为依据,分别对无内置转子光管、内置两叶片转子管、内置翼片转子管在多种倾斜角度下的速度云图、旋流数、气含率、气相速度、湍动能进行分析。结果表明：内置组合转子能够提高流体湍动程度,促进流体混合传质;翼片转子由于其特殊的结构能够显著增加管式光生物反应器中的气含率,提高气液两相间传质效果,传质效果相较于两叶片转子管和光管分别提高53.7%和26.5%;随着管路倾角由0°增大至90°,流体平均湍动能逐渐增加,内置组合转子后平均湍动能增加更加明显,与两叶片转子相比,翼片转子在0°和30°情况下混合传质效果更好。     

叶片宽度比对同心双螺旋静态混合器混合性能的影响

同心双螺旋静态混合器是一种新型的静态混合装置,能够实现流体在混合管内的同心反向螺旋流动。为探究同心双螺旋元件内外叶片宽度比对混合效果的影响规律,利用Fluent中多相流混合模型对低雷诺数状态下该混合器内的混合过程进行了数值模拟,研究结果表明：在较低雷诺数下,同心双螺旋静态混合器与对应尺寸的传统Kenics型混合器相比混合效果明显提升,在叶片宽度比e为0~3/2时混合效果提升6.9%~28%;随着内外叶片宽度比的增大,混合效果呈现先增后减的规律,当e=2/3时混合效果最好;在不同的宽度比下,流体的分离强度沿混合管轴向变化规律相同,即在第一个混合元件内分离强度下降缓慢,第二、三个元件内下降迅速,第四个元件内几乎保持不变而处于维持混合状态,说明本文所研究的混合器使用较少的混合元件即可达到较好的混合效果。     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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