Analytical solution of flow of second-order non-Newtonian fluids through annular pipes

This paper presents an analytical solution to the unsteady flow of the second-order non-Newtonian fluids by the use of intergral transformation method.Based on the numerical results,the effect of non-Newtonian coefficient Hc and other parameters on the flow are analysed.It is shown that the annular flow has a shorter characteristic time than the general pipe flow while the correspondent velocity,average velocity have a(?)aller value for a given Hc.Else,when radii ratio keeps unchanged,the shear stress of inner wall of annular flow will change with the inner radius compared with the general pipe flow and is always smaller than that of the outer wall.     

On the throughflow with swirling inflow in annular diffuser

In this paper, a throughflow with swirling inflow in an annular diffuser is calculated. Under the assumption of smallcross-flow, the flow near inner and outer wall surfaces is calculated based on the three-dimensional momentum integral equation of the boundary layer. The potential fiow outside the boundary layer is cornputed by means of the iteration method based on the velocity gradient equation along the quasi-orthogonal direction of the meridional projection of the stream-line on the meridional surface and the constancy of fiux equation. The numerical results agree with the experiments quite well. This method is useful for analyzing the throughfiow with pre-swirl in the annular diffuser.     

Synthesis and Crystal Structure of {Cu2(pdc)2(4,4′-bipy)(H2O)·(3H2O}2

The title compound {Cu2(pdc)2(4,4′-bipy)(H2O)(3H2O}2 1 (H2pdc = pyridine-2,6- dicarboxylic acid, also known as dipicolinic acid; 4,4′-bipy = 4,4′-bipyridine) has been synthesized by the hydrothermal reaction and its structure was determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group Pī with a = 7.2278(3), b = 10.6259(4), c = 17.7614(6)A, α= 79.5990(10), β = 83.6300(10), γ = 71.8280(10)o, V = 1272.60(8)A3, C48H44Cu4N8O24, Mr = 1371.07, Z = 1, Dc = 1.789 g/cm3, μ = 1.747 mm-1, F(000) = 696, R = 0.0397 and wR = 0.1137 for 3938 observed reflections (I > 2σ(I)). There are two kinds of Cu coordination environments, and each central copper(II) atom is five-coordinated in a distorted square-based pyramidal coordination geo- metry. Four copper(II) atoms are linked by four pdc and two 4,4′-bipy ligands to form an annular rectangle structure. Extensive hydrogen-bonding interactions involving carboxylate O atoms as well as coordinated and free water molecules lead to the formation of a three-dimensional network struc- ture.     

环形薄板轴对称非线性屈曲的样条函数解法

环形薄板的大挠度计算因为边界条件复杂,仅有少数特殊情形的数值解答。均布边缘径向力作用下环形薄板非线性屈曲迄今尚未有研究成果。作者以三次B样条函数为试函数,用配点法计算环形薄板的大挠度。在12种不同的边界条件下,首次计算了环形薄板的压曲临界荷载及超临界荷载作用的变形。在所有的算例中均取得了收敛的数值结果。结果表明样条配点法具有收敛范围大、精度高和计算时间少的优点。     

柔性管内油水环状流流动结构数值模拟

海洋中柔性管道受到外界猛烈撞击,撞击物的不同会导致管道内流道结构发生不同的改变.为探寻流道结构变化对环状流动结构的影响规律,采用N-S方程和湍流模型描述流体运动,用VoF模型与CSF模型追踪油水界面,建立数值方程与分析模型,分析流道不同形式的结构变形、不同程度变形和不同流速下油水环状流在管内的湍动能和漩涡结构演变,及环状流流型的演变和压力场的演变.分析结果表明:凹陷变形程度越大,漩涡的强度及面积越大,V形变形影响远大于○形变形影响,环状流的流型发生改变时仍然保持着水相包裹油相的稳定状态,最大压缩区域的油水界面压强也随之增大,且增速变大.所得结论对研究油水环状流在柔性管道运输中的稳定性具有一定指导意义.      

环形透镜暗场落射照明系统设计及其焦移特性的研究

环形透镜暗场落射照明系统越来越多被应用在特型显微镜上.该系统设计的难点是当采用现有的光学设计CAD软件设计计算时,由于环形透镜所具有的焦移特性的影响,难以保证预期的设计效果,也在一定程度上制约了该系统的推广应用.通过理论分析、实验论证和用自编制的照明设计CAD软件进行光线追迹,较好地确定了该系统的焦移量.并在此基础上提出了照明设计CAD与光学设计CAD软件互动迭代的设计方法.     

STEADY FLOW IN A CURVED PIPE WITH A COAXIAL CORE

In this paper we study the steady annular flow of a viscous fluid into an annular pipe and discuss the effects of the size of the core on the flow properties.     

浮力对环形液池内热毛细对流的影响

为了了解浮力的影响,对水平温度梯度作用时环形液池内的热毛细对流进行了非稳态三维数值模拟,环形液池外壁被加热,半径为40 mm,内壁被冷却,半径为20 mm,液池深度为(1-17)mm,流体为0．65cSt的硅油,其Pτ数为6．7．模拟结果表明,当水平温度梯度较小时,流动为轴对称稳态流动,随着温度梯度的增加,流动将会失去其稳定性,在浅液池内,转化为热流体波,浮力对失稳后的流型无影响,但会使热流体波的振幅下降;在深液池内,在常重力条件下,转化成三维稳定流动,在微重力和小重力条件下,转化为三维振荡流动．     

An analytical solution and analysis of characters for viscoelastic fluid flow in annular pipe

I.Introducti0nLuiCiqunandHuangJunqiI'I(l989),ZhuWeihuiandLuiCiquri1'l(l992)sequentiallystudiedtheaxialflowofsecondorderandMaxwellfluidsandanalyzedtheflowcharactersofthesefluids.Thispaperwillstudyunsteadyrotat0ryflowofsecondorderandMaxwellfluidsinannularpi…     

Flow of Robertson-Stiff fluids through an eccentric annulus

I.IntroductionInthepetroleumindustry,itisusuallythecasethatthedrillingstring(orcasingpipe)isnotlocatedinsidethecenteroftheflowgeometryduringdrillingandcompletillgpl'ocess,this,inturll,willaltertile'11owingbehaviorofdrillingmudandcementslurl.ieswhichtlowinginaneccentricallllulus.OilaccoUlltofviscousofnon-Newtoniantluid,flowillaneccentricannulusdifTeresmuchwiththatinacollcentricannulus.Mailyinvestigatorshaveconductedresearchworksonthisstlbject.Earlyin1935,TaoandDollovallrealizedthattheimpel.t…