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双柱单锥型液-液旋流管内流场的激光诊断 总被引:2,自引:0,他引:2
应用激光测速仪,对一种双柱单锥型液 液旋流管内的流动结构,进行了全场范围内的多工况流动诊断研究.揭示出其切向速度由内旋流区和外旋流区构成,其中内旋流区中的速度分布符合准强制涡关系,外旋流区中的速度分布符合准自由涡关系;轴向速度由上行流动区和下行流动区构成,两者之间在直管段以零速点作分界,在锥体段则以零速区作过渡并伴随有一定的回流出现,且该过渡区或回流区的大小随锥体截面的收缩而减小,直到进入直管段后消失;各湍流量的分布以管芯处最大向外逐渐减小,沿轴向是直管段中的湍流度大于锥体段中的湍流度,而且湍流度在旋流管内具有各向异性的特性. 相似文献
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This paper presents results on the rheological behaviour of suspensions of two kinds of TiO2 particles in two different polymer solutions. The particles differ in their hydrophilic or hydrophobic properties. The dispersing
media are a solution of high molecular weight polyisobutylene in decalin and a solution of a low molecular weight polybutene
in decalin. The concentrations of polymer are adjusted in order to get the same zero shear viscosity. The shear viscosity
measurements display an apparent yield stress in some cases. The existence and the values of the yield stress depend on the
volume fraction of solid particles and on the type of particles. The evolution of the intrinsic viscosity and of the maximum
packing fraction vs the shear rate is interpreted in terms of evolution of the size and of the shape of aggregates of particles
under shear. The effect of temperature on the development of the yield stress is also discussed. The results are completed
by microscopic observations. 相似文献
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力学中的Hamilton体系采用对偶变量描述问题。电磁场采用电场和磁场两类变量描述问题。将力学中的Hamilton体系引入到电磁场问题中,电场变量和磁场变量构成对偶变量,把频域电磁场的基本方程导向对偶方程形式,建立电磁场有限元所需的对偶变量变分原理,由此推导出电磁对偶有限元。将电磁对偶有限元应用于电磁波导计算中,可确定电磁波导的传播常数。文中给出了用电磁对偶有限元方法,计算矩形波导不同模式对应的传播常数的数值计算结果。 相似文献
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Nuri Akkaş 《International Journal of Solids and Structures》1977,13(3):211-220
A ring-stiffened spherical shell is submerged in an acoustic medium. The shell is thin and elastic. The acoustic medium is inviscid, irrotational and compressible. The center of mass of the shell is subjected to a translational acceleration which is an arbitrary function of time. The absolute displacements of the shell are expressed in terms of the relative displacements and the displacement of the base of the shell, base being defined as the rigid ring placed at the equator. The motion of the acoustic medium is governed by the wave equation. The transient response of the shell is investigated numerically. The results are compared with the results of the in-vacuo response. The effects of the plane wave approximation and the base velocity on the transient response of the shell are studied. The numerical results show that the plane wave approximation accurately predicts the response of the shell in the acoustic medium for short times after excitation. The displacements of the shell in fluid are larger than those in vacuo. But when the base of the shell is restrained from translating, the displacements in fluid are smaller than those in vacuo. Therefore, base translation has a very significant effect on the transient response of the shells submerged in an acoustic medium. 相似文献
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We consider an autoparametric system which consists of an oscillator coupled with a parametrically excited subsystem. The oscillator and the subsystem are in one-to-one internal resonance. The excited subsystem is in principal parametric resonance. The system contains the most general type of quadratic and cubic non-linearities. The method of second-order averaging is used to yield a set of autonomous equations of the second-order approximations to the parametric excited system with autoparametric resonance. The Shilnikov-type multi-pulse orbits and chaotic dynamics of the averaged equations are studied in detail. The global bifurcation analysis indicates that there exist the heteroclinic bifurcations and the Shilnikov-type multi-pulse homoclinic orbits in the averaged equations. The results obtained above mean the existence of amplitude-modulated chaos in the Smale horseshoe sense in the parametric excited system with autoparametric resonance. The Shilnikov-type multi-pulse chaotic motions of the parametric excited system with autoparametric resonance are also found by using numerical simulation. 相似文献
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截锥型薄壁结构声振耦合动力特性分析 总被引:1,自引:0,他引:1
采用大型通用软件ANSYS,建立截锥型薄壁结构的实体有限元动力学模型,通过与相关实验数据的对比验证了模型合理性。据此,利用无限元模拟自由声场边界,建立声场-截锥型薄壁结构的直接耦合有限元动力学模型。通过数值仿真分析研究了声场中截锥壳结构的振动特性,并讨论了声振动对结构动力特性的影响。研究结果表明:数值仿真结果和截锥壳声振实验数据比较一致。在考虑声场影响后发现:结构位移共振频率值大多有所降低,结构位移共振频率数量显著增多;在低频下,结构位移响应峰值在声场的影响下明显增大;在高频下则明显减小。 相似文献
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The peristaltic transport of a magnetohydrodynamic (MHD) fluid is exam- ined for both symmetric and asymmetric channels. Hall and ion slip effects are taken into account. The heat transfer is analyzed by considering the effects of viscous and Ohmic dissipations. The relevant flow problems are first modeled, and then the closed form solutions are constructed under the assumptions of long wavelength and low Reynolds number. The solutions are analyzed through graphical illustration. It is noted that the velocity increases but the temperature decreases with the increases in the Hall and ion slip parameters. The axial pressure gradient is less in magnitude in the presence of Hall and ion slip currents. The Hall and ion slip effects are to decrease the maximum pres- sure against which peristalsis works as a pump. The free pumping flux decreases with the increases in the Hall and ion slip parameters. The increases in the Hall and ion slip parameters result in an increase in the size of the trapped bolus. 相似文献
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节理玄武岩体变形模量的尺寸效应和各向异性 总被引:1,自引:0,他引:1
目前系统研究柱状节理玄武岩工程力学特性的成果仅见于美国汉佛德玄武岩核废料埋藏工程和中国西南白鹤滩水电工程。列举了国内外相似工程柱状节理玄武岩的原位试验成果,分析了我国不规则柱状节理玄武岩体的柱体偏转特性和多级结构面发育特征,采用可变形离散元法建立了柱状节理玄武岩体的三维离散元数值模型,通过数值模拟不同尺寸的承压板试验,探讨了尺寸效应和各向异性对试验成果的影响。数值分析表明:承压板的尺寸效应是产生柱状节理岩体水平和铅直原位试验各向异性的主要原因,随着承压板直径的增大,各向异性效应减小,当承压板直径大于6m后,柱状节理玄武岩体可视为各向同性体,研究成果对利用和改造柱状节理岩体具有较好的工程意义。 相似文献
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V. Svetsov 《Shock Waves》2001,11(3):229-244
A new nonstationary regime of the flow around a step and a cylinder was found to exist at high free-stream Mach numbers for
gas specific heat ratios below 1.2. The main features of the flow are strong vortices in the shock-compressed region with
supersonic reversal velocities at the body face. The bow shock wave takes on a complicated shape, fluctuating in time. The
vortical regimes can result from local heterogeneities in the free stream. The case of the heterogeneity is studied in this
paper in the form of a thin thermal layer of limited length. The vortical regime remains in existence after the source of
disturbances is removed. The results have been obtained through computer simulations through the use of Eulerian hydrodynamic
equations and by way of several numerical methods: FLIC, Godunov's scheme, TVD, and PPM. The influence of viscosity on the
development of the vortical regime has been studied by computer solving the Navier–Stokes equations.
Received 21 August 1998 / Accepted 6 June 2001 相似文献
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The results of calculations of water vapor outflow from a source, in which the pressure and temperature are maintained constant, into a vacuum through an orifice in the infinitely thin wall are presented. The calculations are carried out using the direct simulation Monte Carlo method when the processes of water cluster formation/decay in the flow field are taken into account. The vapor flow regimes transient with respect to the Knudsen number are considered. The effect of the cluster formation processes on the parameters of flow which becomes significant for the mole cluster fraction above 4%is analyzed. The effect of “freezing” the mole cluster concentrations with increase in the distance from the source is demonstrated. The influence of the probabilities of monomer and dimer association during pair collisions, used in the model, on themole dimer fraction is investigated. The results obtained are compared with the available experimental data. 相似文献
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The asymptotic and numerical investigations of shock-induced boundary layers in gas-particle mixtures are presented.The Saffman lift force acting on a particle in a shear flow istaken into account.It is shown that particle migration across the boundary layer leads tointersections of particle trajectories.The corresponding modification of dusty gas model isproposed in this paper.The equations of two-phase sidewall boundary layer behind a shock wave moving at aconstant speed are obtained by using the method of matched asymptotic expansions.Themethod of the calculation of particle phase parameters in Lagrangian coordinates isdescribed in detail.Some numerical results for the case of small particle concentration aregiven. 相似文献
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The onset of periodic and aperiodic convection in a binary nanofluid saturated rotating porous layer is studied considering constant flux boundary conditions. The porous medium obeys Darcy’s law, while the nanofluid envisages the effects of the Brownian motion and thermophoresis. The Rayleigh numbers for stationary and oscillatory convection are obtained in terms of various non-dimensional parameters. The effect of the involved physical parameters on the aperiodic convection is studied graphically. The results are validated in comparison with the published literature in limiting cases of the present study. 相似文献
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The propagation of elastic waves is studied in a porous solid saturated with two immiscible viscous fluids.The propagation of three longitudinal waves is represented through three scalar potential functions.The lone transverse wave is presented by a vector potential function.The displacements of particles in different phases of the aggregate are defined in terms of these potential functions.It is shown that there exist three longitudinal waves and one transverse wave.The phenomena of reflection and refraction due to longitudinal and transverse waves at a plane interface between an elastic solid half-space and a porous solid half-space saturated with two immiscible viscous fluids are investigated.For the presence of viscosity in pore-fluids,the waves refracted to the porous medium attenuate in the direction normal to the interface.The ratios of the amplitudes of the reflected and refracted waves to that of the incident wave are calculated as a nonsingular system of linear algebraic equations.These amplitude ratios are used to further calculate the shares of different scattered waves in the energy of the incident wave.The modulus of the amplitude and the energy ratios with the angle of incidence are computed for a particular numerical model.The conservation of the energy across the interface is verified.The effects of variations in non-wet saturation of pores and frequencies on the energy partition are depicted graphically and discussed. 相似文献
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The peristaltic flow of a Johnson-Segalman fluid in a planar channel is investigated in an induced magnetic field with the slip condition.The symmetric nature of the flow in a channel is utilized.The velocity slip condition in terms of shear stresses is considered.The mathematical formulation is presented,and the equations are solved under long wavelength and low Reynolds number approximations.The perturbation solutions are established for the pressure,the axial velocity,the micro-rotation component,the stream function,the magnetic-force function,the axial induced magnetic field,and the current distribution across the channel.The solution expressions for small Weissenberg numbers are derived.The flow quantities of interest are sketched and analyzed. 相似文献
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G. Yu. Kotova K. V. Krasnobaev R. R. Tagirova 《Moscow University Mechanics Bulletin》2009,64(3):64-69
The process of formation and acceleration of a neutral gas envelope during the propagation of an ionization-shock front in a spherical gas cloud is numerically modeled. The velocity and acceleration of the envelope as well as its mass variation with time are determined. The results obtained are compared with some approximate formulas known in the literature. The growth of small velocity perturbations in the dense gas and the effects of mass and momentum accumulation in “finger-like” condensations are studied in the framework of a two-dimensional model. 相似文献
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The results from an experimental study of reduced-gravity two-phase flows are reported in this paper. The experiments were
conducted in simulated reduced-gravity conditions in a ground-based test facility with a circular test section of 25 mm inner
diameter. The flow conditions for which data were acquired lie in the dispersed droplet to slug flow transition and slug flow
regime. Local data were acquired for 17 different flow conditions at three axial locations. The acquired data complement and
extend those discussed in an earlier paper by the authors (Vasavada et al. in, Exp Fluids 43: 53–75, 2007). The radial profiles and axial changes in the local data are analyzed and discussed in this paper. The area-averaged data,
in conjunction with the local data, are discussed to highlight important interaction mechanisms occurring between fluid particles,
i.e., drops. The data clearly show the effect of progressive coalescence leading to formation of slug drops. Furthermore,
the shape of slug drops in reduced-gravity conditions was observed to be different from that in normal-gravity case. The analyses
presented here show the presence of drop coalescence mechanisms that lead to the formation of slug drops and transition from
dispersed droplet flow to the slug flow regime. The most likely causes of the coalescence mechanism are random collision of
drops driven by turbulence eddies in the continuous phase and wake entrainment of smaller drops that follow preceding larger
drops in the wake region. Data from flow conditions in which the breakup mechanism due to impact of turbulent eddies on drops
illustrate the disintegration mechanism. 相似文献