不同雷诺数风沙来流下粒径对S809翼型性能的影响

以风力机专用翼型S809为对象,采用数值模拟的方法研究不同雷诺数风沙来流下粒径对翼型性能的影响.结果表明:0.5μm颗粒绕流时紧贴翼型壁面运动,随着颗粒直径的增大,其运动轨迹逐渐偏离吸力面,且直径越大,偏移距离越远.当颗粒直径为10～50μm时,颗粒绕过前缘后开始偏离吸力面,大于50μm时,其绕流作用减弱,出现直接撞击吸力面的现象;雷诺数越大,近前缘驻点处撞击壁面的颗粒直径越小,且小攻角下撞击壁面的颗粒直径较小;各雷诺数下,50μm颗粒对翼型气动性能的影响最大;雷诺数为2×10~5时,5、50μm颗粒对气相湍动能有抑制作用,50μm颗粒的抑制作用最明显,100μm颗粒会增强气相湍动能.     

微通道中颗粒惯性聚集的力学特性

为揭示微通道内悬浮颗粒惯性聚集现象的机理,基于相对运动原理,利用数值方法研究了单个球形颗粒在方形微通道中的运动状况,并对颗粒的受力特性进行分析.研究发现:较小粒径的颗粒在较高通道雷诺数下可产生惯性聚集现象,但其受到的惯性升力在通道截面横向位置分布具有很大的波动性;惯性聚集位置随通道雷诺数的增大向通道壁面移动,随颗粒粒径的增大向通道轴心移动;颗粒旋转产生的旋转诱导惯性升力使惯性聚集位置向通道壁面移动.惯性升力分为旋转诱导升力和由剪切诱导升力及壁面诱导升力合成的非旋转诱导升力,而后者是惯性升力的决定性部分.     

气液喷射器中不同粒径分布函数下液滴轨迹数值模拟

采用数值模拟的方法研究气液喷射器内液滴的运动轨迹,液相流场采用离散相模型。研究粒径和液滴速度对液滴运动轨迹的影响,探索了单一液滴和不同Rosin—Rammler分布函数下液滴的运动轨迹。结果表明,气相旋转气流并没有对液滴的轨迹造成太大的影响,液滴仍是以接近直线的形式向前运动;离散相液滴最终的速度主要取决于气相速度,与液滴粒径大小、粒径分布和初速度无关;液滴的运动轨迹随着Rosin—Rammler分布中均匀性系数的增加,液滴速度的增大和平均粒径的减小而发生改变,造成离散相液滴喷出趋向于集中和液滴相对远离壁面。     

滑阀间隙中方形微米颗粒的旋转现象

将滑阀微米配合间隙简化为二维模型,敏感颗粒外形近似为方形.运用COMSOL软件中流固耦合模块的任意拉格朗日-欧拉方法,对方形微米颗粒在滑阀间隙内的运动特征进行仿真研究.发现了颗粒在滑阀间隙中的旋转现象,此现象从微观层面科学地解释了非圆球形颗粒物诱发滑阀卡滞的机理.流固耦合计算显示,微米颗粒跟随油液流动的同时,颗粒在间隙中产生旋转运动,同时颗粒中心的运动轨迹有上下波动;均压槽中颗粒中心的运动轨迹呈抛物线状,径向位移的最大值约为均压槽深度的1/4,随着方形颗粒尺寸的增大,其沿径向位移的最大值呈减小趋势.     

应用光学原理研究原油沥青的聚沉过程

利用Turbiscan Lab 稳定性分析仪研究了原油/甲苯混合体系的稳定性。将不同加量的沉淀剂应用于1：9 的原油/甲苯混合体系中,通过测量原油/甲苯的透射光和背散射光强度随时间的变化,可描述混合体系中沥青的聚集和沉淀过程,有助于分析原油不稳定性发生的机理,并定量分析了沥青聚沉过程中的颗粒粒径大小、粒径增大速率和颗粒沉降速率等。实验表明,随着沉淀剂的加量从80.0% 增加到90.9%,混合体系中沥青的聚集速率从192.216 μm/min 增加到5 332.120 μm/min,粒径从10.0 μm 增大为53.4 μm ,沉积速率从0.17 mm/min 增加到0.46 mm/min。     

基于EDEM-FLUENT耦合的滚筒冷渣机颗粒轴向扩散运动

基于欧拉-拉格朗日、离散单元法理论,利用EDEM-FLUENT耦合方法,考虑了气相对颗粒的相互作用,以及颗粒与颗粒之间的碰撞,对滚筒冷渣机六棱形冷渣管料床中灰渣颗粒轴向扩散进行了数值模拟分析,得出了灰渣颗粒在填充度25%,颗粒滚落状态下的动态休止角θd=29°,安装倾斜角3°工况下,轴向扩散运动随滚筒转速n(5 r/min ~ 10 r/min)、颗粒粒径d(1.5 mm ~ 3.5 mm)的变化规律。实验结果表明：当粒径一定时,轴向扩散系数随着转速n的增大而增大,相比5 r/min转速,10 r/min转速下颗粒轴向扩散系数增大了23.6%;当滚筒转速一定时,轴向扩散系数随着粒径的增大而增大。粒径d从1.5 mm增加到3 mm及3.5 mm时,轴向扩散系数分别增大了3倍和7.06倍。轴向扩散系数越大,颗粒轴向运动就越剧烈,滚筒出力越强,炉渣处理效率越高。     

催化剂颗粒在弯道与渐扩管组合管系内的运动分布特征

采用数值模拟方法对弯道与渐扩管相连的管道内气固两相流运动分布特性进行研究.主要分析弯道和渐扩段气相流场分布特征及气相回流卷吸作用下颗粒运动分布特性,研究沿出口水平管段二次流结构发展变化及其对颗粒分布及沉降的影响.针对不同入口速度下,水平管内气流速度、截面平均二次流速度和颗粒质量浓度分布规律进行研究分析.研究结果表明:沿弯道后的水平管道,二次流速度很快下降;二次流对颗粒的卷吸搬运作用,降低颗粒在管道截面的局部聚集浓度;当入口气流速度为4 m/s或更小时,水平管内上升二次流速度较小,颗粒沉降现象明显;当速度增大到6 m/s,水平管截面颗粒质量浓度分布较均匀.     

气-粒两相螺旋流光整加工中壁面受力的数值模拟

气-固两相螺旋流光整加工技术是利用气体的旋转运动,推动固体颗粒作螺旋运动,使固体颗粒在离心力的作用下对工件孔内表面进行滚压、磨削等,最终实现对工件孔内表面光整加工的目的。本文运用FLUENT软件,采用基于各向异性的雷诺应力模型和能反映颗粒运动复杂经历与壁面碰撞的随机轨道模型,分别对气流场和颗粒进行了等直径工件孔内在不同进口条件、不同颗粒个数、等多种工况下的颗粒运动轨迹、壁面受力的数值模拟,得出了较为合适的模拟结果,为进一步实验研究提供了理论依据。     

90°方形通风弯头内颗粒物沉积的模拟研究

采用拉格朗日随机轨道模型,模拟追踪了不同送风速度下粒径1～100μm的颗粒在90°方形通风弯头内的运动轨迹.考虑了弯头尺寸、湍流强度以及壁面粗糙度等因素对沉积率的影响,结果表明:当处于紊流过渡区(5K+30)时,壁面粗糙度对颗粒沉积率有明显的影响,沉积率随着Stk数和弯曲比的增大而不断增大,且弯曲比为4的弯头比较利于颗粒的输运.     

垂直壁面附近单气泡运动特性可视化研究

为了明晰气泡在壁面附近的浮升行为及运动规律,采用高速摄影结合阴影图像处理算法,对水中近壁面气泡的迁移行为进行了可视化研究,探讨了不同初始离壁距离条件下气泡运动轨迹、形状和上升速度的变化规律。研究结果表明：在气泡上升的初始阶段,当气泡与壁面量纲一间距S^*≤1.4时,气泡趋向于壁面运动;当S^*≥2.05时,气泡远离壁面运动。在本研究的参数范围内,当S^*≤0.61时,气泡与壁面发生周期性碰撞,碰撞瞬间气泡水平速度发生反转,气泡形状由椭球形突变为球形;当S^*≥1.4时,气泡与壁面不再发生碰撞,气泡呈“之”字形振荡上升,上升轨迹近似于正弦曲线。随着气泡初始离壁距离进一步增加,气泡上升轨迹振荡的幅度减小,周期增大,壁面效应逐渐减弱;当气泡变形程度减小时,气泡纵横比的振幅变大。气泡水平速度呈现与气泡轨迹相同的变化趋势,振幅减小,周期增大;而气泡垂直速度基本不随初始离壁距离的改变而变化。当气泡与壁面不发生碰撞时,气泡垂直速度的振荡周期为水平速度振荡周期的1/2。     

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     

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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