运输机升阻特性仿真与风洞试验相关性方法

以M3飞机配装某型发动机三维模型为研究对象,采用CFD方法对整机流场进行数值计算。对于带动力短舱模型,利用分区拼接网格技术对发动机内流场和飞机外流场进行网格划分和拼接;在此基础上采用雷诺平均N-S方程,基于S-A湍流模型,开展了不同发动机状态、马赫数及攻角的仿真计算。以FNPR=1.61时,试验获得的升阻系数作为基准,在不同攻角下,获得CFD计算结果的修正因子,结果表明：修正后的数值计算结果与风洞试验获取的升力特性曲线,贴合程度好,在攻角小于14°内误差小于3%;修正后的阻力特性曲线整体趋势与风洞试验一致,误差小于10%,阻力系数都是随攻角的增大而增大,且在攻角大于10°后快速增大。     

螺旋桨运输机进气道阻力特性分析

以某型螺旋桨运输机带动力装置飞行试验台为研究对象，建立了三维流场模型，采用CFD进行了网格划分及数值计算。以前期飞行试验数据和发动机热力循环模型计算结果为边界条件，开展了不同飞行马赫数、高度及桨叶角的数值计算。选用桨叶角表征发动机状态，分析了不同飞行高度、马赫数、螺旋滑流对进气道前罩作用力和附加前体力影响的变化规律。计算结果表明：不同高度、桨叶角及马赫数均会改变进气道阻力，在马赫数0.5，高度4 km状态下，桨叶角由40°增大至50°，前罩作用力减小1 700 N，附加前体力减小3 600 N,而附加前体力系数及前罩作用力系数随飞行高度基本不变。进气道阻力特性研究为后续试飞中确定涡桨发动机外部阻力特性分析提供了数据支持。     

基于CFD技术的螺旋桨非定常流场数值模拟

针对单独螺旋桨模型,基于动态结构网格搭接技术,采用CFD方法对其非定常流场进行了数值模拟。首先针对全部外形生成多块点搭接和面搭接两套计算网格,通过分析两套网格的计算结果,验证动态网格搭接技术的可行性和正确性,得出螺旋桨性能参数随转速的变化规律;在此基础上分析了雷诺平均NS(RANS)方程和Euler方程的数值模拟结果;最后研究了攻角对单独螺旋桨性能参数的影响。研究结果表明：动态网格搭接技术能够很好地模拟非定常螺旋桨的性能参数;螺旋桨的拉力系数和功率系数都随着转速的增加而增大;对螺旋桨非定常流场进行数值模拟时,采用Euler方程就能够满足工程精度的需求;攻角0度时单片桨叶的拉力系数和转矩系数都是恒值,而在攻角10度时却都呈现出周期性的正弦曲线。     

复合材料螺旋桨非定常流固耦合特性数值分析

针对船用复合材料螺旋桨在非均匀流中的水弹性问题,采用雷诺平均纳维-斯托克斯方法(RANS)和有限元方法(FEM)分别求解螺旋桨流场和结构场,并结合滑移网格和动网格技术,建立了船用复合材料螺旋桨双向瞬态流固耦合计算方法.以DTMB4381桨为对象,采用ANSYS ACP构建复合材料桨有限元模型,计算了正交各向异性碳纤维复合材料(CFP)桨在均匀流场和非均匀流场中的水动力性能和结构响应.研究表明:CFP桨的流固耦合效应较小,在均匀流中具有与刚性桨基本相当的水动力性能;CFP桨在非均匀流中桨叶结构响应(位移、速度和加速度)在高伴流区域、叶梢和导边区域较大,变化也更为剧烈.     

斜流中泵喷推进器流场变化规律数值分析

基于SST(剪切应力输运)k-ω湍流模型与滑移网格技术,对不同进速系数(J=0.95,1.18,1.58)及不同斜流角(β=0°,10°,20°)下泵喷推进器流场变化规律进行了数值分析.利用P4119桨进行了数值方法验证,并进行网格无关性验证.为保证计算结果的准确性,采用全通道模型及全结构网格进行数值计算.计算结果表明:随着斜流角的增大,横向力和垂向力出现明显波动,不同斜流角间的波动幅度相对一致,且随着斜流角的增大而减小;随着进速系数及斜流角的变化,压力系数在转子导边、随边处出现明显波动差异,定子叶片压力系数波动比较稳定.     

桨叶调节对轴流式水轮机甩负荷特性影响研究

提出了轴流转桨式水轮机模型甩负荷过渡过程三维非定常数值模拟方法,采用动网格及网格重构方法实现了甩负荷过程中导叶和桨叶的动态关闭过程,获得了相关工作参数变化规律和内部流场变化情况.结果表明:计算得到的转速和测点静压变化规律与模型试验结果较一致,最大转速误差约为1.8%,验证了三维数值模拟方法的可靠性;当甩相同负荷,导叶采用相同关闭规律时,导叶关闭规律对参数变化起着决定性作用;最大向上轴向力出现在导叶关闭结束时刻,合理设置导叶关闭分段点位置将有效改善过渡过程品质;桨叶小角度关闭对抑制转速上升和压力波动作用不明显,反而会加剧轴向力波动和最大向上轴向力值,从降低最大向上轴向力防抬机角度,桨叶保持不动比桨叶小角度关闭更有利.本研究实现了桨叶与导叶双重调节的动态仿真.     

双搅拌高效澄清萃取槽混合室均混时间的数值模拟

利用CFD软件FLUENT120,采用Realizablek-ε湍流模型、Eulerian多相流模型及Morsi Alexander相间曳力系数模型,使用滑移网格法处理桨叶的旋转区域,对新型萃取槽混合室内的液-液体系的均混时间以及搅拌功率进行数值模拟.结果表明:随着搅拌转速的增大,搅拌桨消耗的功率增加,水油两相的均混时间减小.搅拌桨转速达到400r/min后,增大转速则搅拌功率继续增大,但对液-液两相均匀混合时间的影响不大.     

内锥型空心弹阻塞临界入口锥角仿真研究

为了研究内锥型空心弹的阻塞现象与入口锥角的关系,仿真研究了入口锥角对空心弹流场的影响。在喉道与入口截面积比为0.6的条件下,基于可压雷诺时均Navier-Stokes(RANS)方程与单方程Spalart-Allmaras(S-A)湍流模型进行研究。对斜坡流场进行数值仿真,并与实验结果对比,验证了该文方法的可行性。采用该文方法模拟了入口锥角分别为10°和30°条件下,空心弹在来流马赫数为2.5时的流场,发现入口锥角是造成气流阻塞的重要影响因素。在来流马赫数为2.5时,利用穷举法计算了入口锥角为10°～30°的流场变化情况,得到空心弹发生阻塞的临界入口锥角为17.8°。计算了空心弹在来流马赫数为2～4时的临界入口锥角,结果表明临界入口锥角随来流马赫数的增大而增大。     

搅拌桨内部三元流动计算

对计算叶轮机械内部三元流动的任定准正交面法略加个性后，用于计算搅拌桨内部的流动。计算所得的桨叶排出流的三维速度分布与实验结果大体一致。计算结果表明，不同转速下的桨叶排出流的无因次轴向速度分布是重合的，桨叶直径，叶片安放角，盘面比，轮毂比对桨叶排出流的速度分布的均有影响。     

变航态推进器设计及水动力性能分析

为了改善变航态推进器的推进性能,设计了一种将前桨和后桨集成安装的水下变航态推进器.该变航态推进器采用了高速航态前桨和低速航态后桨相结合的方式,通过两个螺旋桨的转速匹配来提高推进性能.使用切割体网格划分方式对流场域进行网格划分,对推进器周围的流场进行网格加密,采用滑移网格实现螺旋桨的旋转.使用雷诺时均-斯托克斯(RANS)方法对变航态推进器的水动力特性进行了分析.从数值模拟结果可以看出:转速匹配有利于水动力性能的提升,但由于存在摩擦阻力,转速匹配不能完全抵消高速螺旋桨引入所带来的水动力性能下降;同时,旋转的前桨有助于降低后桨表面受到的不定常力.     

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