深井条件下超高压射流钻头水动力学特性研究

采用Reliable k－ε湍流模型对高压射流双流道钻头内高压高速三维流道进行了水动力学设计，并提出了“流体齿”的概念。通过计算获得了高围压井底条件下一股高压小排量射流和两股低压大排量射流相互作用时井底湍流场的流动规律。研究结果表明，该条件下的射流结构可划分为范围很小的核心高速区和速度衰减区，井底漫流区的厚度随着高压射流离井底距离的减小而增大。在钻头体附近和环空返流区内流体表现为螺旋流动状态。     

多股受限撞击射流井底压力特征的数值模拟

应用大涡模拟方法，对不同的喷嘴尺寸、个数和喷嘴组合条件下井底多股受限撞击射流的流动特性进行了数值模拟。对模拟结果的分析研究表明，多股撞击射流的井底压力分布存在低压区、高压区和中等压力区三个区域。高压区为射流撞击区，低压区为漫流区，中等压力区为射流相互干扰区。在喷嘴出口总面积相同的条件下，保持中心喷嘴直径大于或等于边喷嘴直径，井底压力的分布对清岩和破岩更为有利。     

多股受限撞击射流井底压力特征的数值模拟

应用大涡模拟方法，对不同的喷嘴尺寸、个数和喷嘴组合条件下井底多股受限撞击射流的流动特性进行了数值模拟．对模拟结果的分析研究表明，多股撞击射流的井底压力分布存在低压区、高压区和中等压力区三个区域．高压区为射流撞击区，低压区为漫流区，中等压力区为射流相互干扰区．在喷嘴出口总面积相同的条件下，保持中心喷嘴直径大于或等于边喷嘴直径，井底压力的分布对清岩和破岩更为有利     

高速超高压水射流喷管内外湍流流场的数值模拟

基于对现有研究成果的分析，选用了应用最广泛的涡动粘性系数法中的ｋε模型对高速超高压射流辅助钻井钻头井底湍流流场进行了数值模拟，研究了高速超高压射流的结构特性和喷管内外流场的分布规律．模拟精度基本达到了工程技术要求．对高速超高压射流喷管内外（井底）湍流流场的全场数值模拟表明，高速超高压射流井底流场是由射流冲击区、漫流区、涡流区和返流区组成的，对于有较大锥形角的斜面或曲面内流道喷嘴，一般可不必考虑流体的压缩性影响（约为５％）．     

高速超高压水射流喷管内外湍流流场的数值模拟

基于对现有研究成果的分析，选用了应用最广泛的涡动粘性系数法中的－κ－ε模型对高速超高压射流辅助钻井钻头井底湍流流场进行了数值模拟，研究了高速超高压射流的结构特性和喷管内外流场的分布规律。模拟精度基本达到了工程技术要求。对高速超高压射流喷管内外湍流流场的全场数值模拟表明，高速超高压射流井底流场是由射流冲击区，漫流区，涡流区和返游戏我组成的，对于有较大锥形角的斜面或曲面内流道喷嘴，一般可不必考虑流体的     

井底受限射流流场的数值模拟

考虑到深井、超深井中井底围压对射流流场有一定的影响 ,建立了井底受限射流流场的物理模型。采用k ε模型 ,并对模型的主要系数进行了优选 ,用有限元方法对围压条件下井底受限射流的流场进行了数值模拟。给出了高围压条件下射流轴心动压力、径向速度和轴心线上湍流动能等流场参数分布 ,并与零围压条件下淹没自由射流的参数进行了比较 ,得出了高围压条件下受限射流轴心动压力衰减规律的数学模式 ,进一步完善了钻井水力参数设计的理论和方法。     

楔形体回流区的射流汇合

本文建立了两股二维不可压缩湍流射流在楔形体后汇合的数学模型,分析了汇合点位置、回流区中压力分布、射流形状和汇合点下游的流动情况,并测量了整个流场的速度分布、湍流能量分布和压力分布.     

射流涡流排水采气模拟实验台研制与应用

研制了新的排水采气模拟高压实验台,适用于研究低压低产气井的射流涡流排水采气工艺和观测井下油管、井底多相流体流动状态。分析了研究射流涡流排水采气工艺的重要性,介绍了该实验台的基本组成。为优化排水采气工具,设计开发了一系列射流涡流及组合工具的实验项目,举例说明其可行性,使实验装置提升为多功能、综合性的教学、科研平台。     

井底受限射流流场的数值模拟

考虑到深井、超深井中井底围压对射流流场有一定的影响，建立了井底受限射流流场的物理模型。采用κ-ε模型，并对模型的主要系数进行了优选，用有限元方法对围压条件下井底受限射流的流场进行了数值模拟。给出了高围压条件下射流轴心动压力、径向速度和轴心线上湍流动能等流场参数分布，并与零围压条件下淹没自由射流的参数进行了比较，得出了高围压条件下受限射流轴心动压力衰减规律的数学模式，进一步完善了钻井水力参数设计的理论和方法。     

来流特性对高速扩压叶栅端壁射流旋涡的影响

在进口马赫数Ma=0.67的高速平面扩压叶栅上,开展了不同来流附面层厚度和湍流强度对端壁射流旋涡发生器控制效果的影响研究。结果表明,与来流湍流强度相比,进口附面层厚度对栅内流动的影响更大,随着其厚度的增加,栅内二次流动增强,损失增大;来流湍流强度对叶栅气动性能的影响减弱。射流旋涡在较小附面层厚度条件下减小栅内损失的效果随着湍流强度的增加而减弱,甚至会恶化其气动性能;而当附面厚度较大时,射流穿透能力减弱,湍流强度的增大将减小射流旋涡上洗区掺混损失并减缓其下洗侧与吸力面间端壁附面层的发展,叶栅气动性能的提高更加显著。当δ=15%H、T_u=10%时,射流旋涡使得栅内损失减小达8.4%。     

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     

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