管壳式换热器内气液两相流冲刷垂直管束的阻力特性研究

本文对垂直布置的管壳式换热器中，气液两相流冲刷管束时的流动阻力进行了实验研究。实验段采用管壳式换热器模型，其圆形外壳内的管束由４９根管子组成，并沿长度方向用三块折流板将管束分成四个冲刷流程。当气液两相流自下而上冲刷管束时，分别测量摩擦阻力和局部阻力，并用分相流动模型进行分析，得到良好的计算关联式。     

冰浆在180弯管内流动阻力特性的试验研究

对冰浆在水平180°弯管内流动进行了试验研究,并与清水的流动特性进行了比较,得到了其流动局部阻力的计算关联式.     

冰浆在180°弯管内流动阻力特性的试验研究

对冰浆在水平 １８０°弯管内流动进行了试验研究,并与清水的流动特性进行了比较,得到了其流动局部阻力的计算关联式．     

推进－迭代算法计算效率的研究

本文对求解三维定常超音速动性流场的一次空间推进，在每一个推进站沿伪时间层局部迭代的推进－迭代算法作了进一步的研究．在每一推进站（侧向平面）沿伪时间层局部迭代时，给出了四种不同的隐式迭代方法，即沿侧面两个方向（法向和周向）全用隐式；法向隐式而周向采用Ｇａｕｓｓ－Ｓｉｌｄｌｅ来回扫描迭代；法向隐式而周向显式及以系数矩阵谱半径代替系数矩阵的简化标量隐式算法．用这四种算法模拟了三维球锥黏性绕流，给出了四种不同算法的计算效率和收敛特性比较．     

超音速粘性流动的SUPG有限元数值解法

本文构造了准简化 N-S 方程组的 SUPG(Streamline Upwind/Petrov-Galerk-in)加权剩余式,并利用该方法对 Burgers 方程、无粘性激波反射问题、以及超音速平板和压缩拐角的层流流动作了数值求解。计算结果表明,本文方法是精确、收敛和稳定的。     

两层涂布流动的非线性稳定性

研究了两层涂布流动的非线性稳定性问题,得到了两层涂布流动的亚临界有限扰动阈值和各阶演化系数。     

钝锥三维粘性绕流背风面分离的数值模拟

本文将作者在文献[1]中提出的方法推广应用于求解三维可压缩 N-S 方程和简化 N-S 方程,并对近似因式分解法应用于三维问题的稳定性进行了分析。指出,对二维问题原无条件稳定的格式,经近似因式分解后仍是无条件稳定的;对于三维问题,原无条件稳定的格式经普通近似因式分解后所得到的格式可能是不稳定的或条件稳定的。利用系数矩阵分裂法所得到的近似因式分解格式可仍是无条件稳定的,只要适当加大分裂后的系数反差即可。 文中给出了钝锥超音速三维粘性绕流结果。得到了背风面分离的流动图像,物面压力值与实验值吻合。     

斜向自由剪切层流动特性的实验研究

本文用恒温热线风速仪对斜向自由剪切层流场进行了测量,得到了流场动量厚度、平均速度和二阶脉动速度相关统计量的变化规律;给出了不同位置处纵、展方向上速度信号随时间变化的波形、概率密度分布、自相关和互相关函数以及功率谱;表明斜向自由剪切层流场中有螺旋形涡存在的特征.     

二维轴对称耦合流动问题的解析解及应用

耦合流动问题与矿井开采中许多重要工程问题有密切联系:基于 Biot 三维固结理论导出了平面轴对称耦合流动与非耦合流动的场方程,得到了给定势问题的解析解.对耦合和非耦合两种情况进行了比较,并介绍了其在采矿工程中的应用.     

全长粘结式锚杆的非局部摩擦分析

本文对Oden等提出的非局部摩擦模型进行了修正,得到了修正后的非局部摩擦模型.并应用于全长粘结式锚杆问题.文中利用Mindlin问题的位移解导出的全长粘结式锚杆沿杆体表面所受的剪应力的弹性解,对全长粘结式锚杆进行非局部摩擦分析,得到了在修正后的非局部摩擦模型下的全长粘结式锚杆的侧剪应力.文中修正的非局部摩擦模型下的全长粘结式锚杆的剪应力分布规律与试验得到的结果以及局部摩擦模型(库仑模型)下的计算结果进行了对比,结果表明修正的非局部摩擦模型下的计算结果与实验更符合.因此在描述此锚杆剪应力时,非局部摩擦模型比局部摩擦模型(库仑模型)更接近的实际.     

幂律流体圆柱绕流的格子波尔兹曼模拟简

基于插值补充格子波尔兹曼方法和幂律流体的本构方程,建立了贴体坐标系下适用于幂律流体的格子波尔兹曼模型,模拟了幂律流体的圆柱绕流问题,采用非平衡外推格式处理圆柱表面的速度无滑移边界,利用应力积分法确定曳力系数和升力系数,并与基于标准的格子波尔兹曼方法和有限容积法获得的数值数据进行对比,吻合良好. 进行了网格无关性验证之后,分析了稳态流动时,不同雷诺数下幂律指数对于尾迹长度、分离角、圆柱表面黏度分布、表面压力系数及曳力系数的影响,以及非定常流动中,幂律指数对于流场、曳力系数、升力系数和斯特劳哈尔数的影响. 获得的变化规律与基于其他数值模拟方法得到的结果相一致,充分验证了模型的有效性和正确性. 结果表明：插值补充格子波尔兹曼方法可以用来模拟幂律流体在具有复杂边界流场内的流动问题,通过引入不同的非牛顿流体本构方程,该方法还可以进一步应用于其他类型的非牛顿流体研究中.     

LATTICE BOLTZMANN SIMULATION OF POWER-LAW FLOW PAST AN ELLIPTIC CYLINDER

基于格子波尔兹曼方法(lattice Boltzmann method) 和幂律流体本构方程, 建立二维流动模型, 将充分发展的速度分布与理论解进行对比, 吻合良好. 对幂律流体的圆柱绕流进行模拟, 采用了反弹格式的无滑移圆柱边界, 并使用应力积分法计算阻力系数, 分析了稳态圆柱绕流时, 阻力系数随幂律指数n 以及雷诺数Re 的变化规律. 分析了椭圆横轴/纵轴长度比和幂律指数n, 对压力系数C_p 和黏度系数C_v 的影响. 得到的变化规律与有限元方法规律一致, 验证了格子波尔兹曼模型的可行性.     

幂律流体两平行圆板间径向扩散层流进口段流动阻力的分析

在文献￣［２，３］的基础上，将其方法推广到幂律流体流动，首先导出幂律流体两平行圆板间径向扩散层流边界层的动量积分方程和能量积分方程。通过对动量积分方程的求解，对幂律流体的进口段长度以及进口段效应压力损失和流量修正系数进行了分析计算，并且讨论了幂律流体的流动指数ｎ与进口处修正雷诺数Ｒｅ＿１对进口段长度和压力损失系数的影响。特别是当ｎ＝１时，本文的解与文献￣［３］中的解完全一致，因而间接验证了本文结果的可靠性。     

Effects of shear-thinning/thickening nature on the stability of Couette-like flow with uniform crossflow

The linear stability of wall-injected pressure- driven Couette-like flow in power-law fluids is studied. Previous study on this kind of flow for Newtonian fluids by Nicoud and Angilella [Phys. Rev. E 56, 3000 （1997）] was extended to power-law fluids to understand the effects of shear-thinning/thickening nature on the flow stability. A related expression between the critical crossflow Reynolds number for Newtonian fluids and that for power-law fluids is obtained as the streamwise Reynolds number is large enough based on numerical computations, and verified theoretically in the case of a limiting condition with the power-law index.     

Flow of a Nonlinearly Viscous Fluid over the Surface of a Rotating Flat Disk

The flow of a nonlinearly viscous (power-law) fluid over the surface of a rotating flat disk is investigated. A solution form which makes it possible to reduce the complete system of partial differential equations to a system of ordinary differential equations is found. This system is integrated using the Runge-Kutta method and reduction to a Cauchy problem on the basis of Newton's method. The velocity and pressure fields in a power-law fluid film flowing over the surface of a rotating flat disk are found numerically.     

Studies on the law of laminar helical flow of power-law fluid in eccentric annuli

According to the principle of fluid mechanics,the law of laminar,helical flow of power-law fluid in eccentric annuli is studied extensively in this paper.The apparent viscosity,velocities distribution of laminar helical flow of power-law fluid are discussed and calculating methods of flow rate and pressure loss are presented.The factors influencing flow are also analysed.On the basis of theoretical studies some new results of the present paper are compared with the theories of the helical flow of the power-law fluid in concentric annuli.The test verified that theoretical formulas in this article are proper and general.They can be used for calculating hydraulic parameters in drilling engineering.     

On the case when steady converging/diverging flow of a non-Newtonian fluid in a round cone permits an exact solution

This communication considers the steady converging/diverging flow of a non-Newtonian viscous power-law fluid in a round cone. The motion is driven by a sink/source of mass at the origin. It is shown that the problem permits exact similarity solution for a particular value (n=4/3) of the fluid index. In this case a complete set of governing equations can be reduced to an ordinary differential equation, which is solved numerically for different values of the main non-dimensional parameters (the cone angle and the dimensionless sink/source intensity).     

非牛顿幂律流体绕可渗透平板非定常流动的相似解

文（１）研究了平板表面吸吮速度按照某一规律变化时，非牛顿幂律流体绕可渗透平板非定常流动的运动方程的相似解。本文补充研究吸吮速度按照其它一些规律变化时该问题的准确的或近似的相似解。     

Self-similar solutions of the problem of formation of a hydraulic fracture in a porous medium

The problem of hydraulic fracture formation in a porous medium is investigated in the approximation of small fracture opening and inertialess incompressible Newtonian fluid fracture flow when the seepage through the fracture walls into the surrounding reservoir is asymptotically small or large. It is shown that the system of equations describing the propagation of the fracture has self-similar solutions of power-law or exponential form only. A family of self-similar solutions is constructed in order to determine the evolution of the fracture width and length, the fluid velocity in the fracture, and the length of fluid penetration into the porous medium when either the fluid flow rate or the pressure as a power-law or exponential function of time is specified at the fracture entrance. In the case of finite fluid penetration into the soil the system of equations has only a power-law self-similar solution, for example, when the fluid flow rate is specified at the fracture entrance as a quadratic function of time. The solutions of the self-similar equations are found numerically for one of the seepage regimes.     

Exact solution to peristaltic transport of power-law fluid in asymmetric channel with compliant walls

Effects of compliant wall properties on the peristaltic flow of a non-Newtonian fluid in an asymmetric channel are investigated.The rheological characteristics are characterized by the constitutive equations of a power-law fluid.Long wavelength and low Reynolds number approximations are adopted in the presentation of mathematical developments.Exact solutions are established for the stream function and velocity.The streamlines pattern and trapping are given due attention.Salient features of the key parameters entering into the present flow are displayed and important conclusions are pointed out.