气液两相流界面波的双平行电导探针测量方法研究

使用双平行电导探针，通过测量气液两相瞬时液膜厚度，来反映气液两相流界面上的波动规律，对经测量系统进行了理论和实验研究，根据界面波的物理特性，设计出一种能够快速准确地测量液膜厚度的电导探针系统，并且提出了一种不受实验条件变化影响的探针标定方法。通过对水平管内空气－水气液两相流分层流界面厚度的测量，证明这种方法是切实可行的。     

高温高压汽包液-气界面测量误差分析——FST-3000系列智能浮筒液位（界面）计在锅炉汽包上的应用探讨

由于设计工作状态与实际运行工作状态的不相一致，高温高压汽包液。气界面测量中往往出现较大的测量偏差。本文就FST-3000的性能、设定方法和现场调试对测量精度问题展开了讨论，探讨如何达到最佳的测量效果。[编者按]     

树平1井低碳混合有机酸解堵技术可行性探讨

水平并开采井段长，在钻完井、作业过程中所需的钻完并液等液量较大。相对于一般的直井来说，存在着作业周期长、钻开油层时工作液特殊、浸泡时间长等问题，这将导致油层堵塞，产能下降，影响水平井开发的效果。目前水平井的主要增产措施是酸化解堵，然而，水平井和直井的酸化处理过程存在显著的差别。对水平并来说，其酸化长度较大、酸用量较大、费用较高。水平井酸化的难点在于实现整个水平段均匀酸化，同时，根据水平特殊的伤害原因，如何从本质上解除油层伤害，最大限度恢复产能，在常规解堵技术基础上，需要有针对性引进增能复产工艺技术。目前常规井酸化工艺技术不能满足水平井酸化技术要求。本文根据树平1井钻完井生产过程的实际情况，综合分析该井在钻完井、作业、采油等过程中对储层造成的各种伤害原因，优选出适合的低碳混合有机酸药剂配方，并利用新工艺最大限度恢复该井产能。     

圆管中气液分层层流及减阻规律

本文研究了圆管中，气液分层层流流动情况下的阻力变化规律。首先研究了管道壁面附近掺气后，层流流动阻力的变化规律，然后研究了圆管中气液分层液动情况下，阻力变化趋势。     

液氮薄膜在切应力作用下的降膜流动和传热模型

以钎焊板式换热器当中液氮薄膜为研究对象,通过建立在切应力作用下层流饱和蒸发液氮薄膜的传热特性的物理模型,推导出了无量纲液膜厚度和表面传热系数与气液界面切应力、界面对流换热强度、初始雷诺数和流动长度之间的非线性关系式.     

水下超声速气体射流的初始流动特性研究

为研究水下发射过程中高温高压火药燃气喷射进入液相水过程的流体形态变化与流动特性,采用Mixture多相流模型与蒸发与凝结模型建立了二维轴对称水下超声速气体射流的数值计算模型并进行了相关的数值模拟,得到水下超声速气体射流的初始流动结构。数值结果表明,超声速气体与水介质的强撞击会在气液界面上形成一个强压缩区,且连续撞击形成的压力波反传,使喷管出口射流核心区流场出现周期性脉动。因气液界面上的强剪切作用,而在气液混合区内形成复杂的小激波结构,小激波结构的出现加速了气液界面的失稳,从而促进了气液掺混效应。另外,在气泡内会形成典型的欠膨胀射流结构,因而气泡内的流动特征与单相超声速气体射流情况类似。     

提高机采井系统效率的措施

抽油机井效率是抽油机在提液过程中其有效功与系统输入能量的比值，反映抽油机井采油的能耗水平机械采油经济技术之一。提高机采井系统效率，是降本增效的有效途径。本文主要介绍了机采井效率的计算方法、影响因素，对提高机采井系统效率的措施进行探讨。     

多孔媒质界面上声波的反射和折射

一、引言 利用地震波进行石油勘探和利用超声波检测多孔材料时,了解声波在流体饱和的多孔媒质界面上的反射和透射特性十分重要。与一般的各向同性固体不同,多孔媒质中可以有传播速度不同的三种波型(快纵波、慢纵波和切变波)[1,2],其界面上声波的反射和折射行为较为复杂。Stoll[3]曾研究过流体中传播的平面纵波入射到水饱和的沉积岩表面上的反射系数,但未具体计算在多孔媒质中的折射波的振幅,也未考虑在多孔煤质中传播的声波入射到流体(或固体)界面时的反射和折射特性。Hovem[4]在研究声波通过浸没在流体中的多孔媒质栩透射特性时,为简便地…     

Ti-N薄膜与钢基体界面显微结构的透射电镜研究

用透射电镜分别研究了空心阴极离子镀加Ti底层和不加Ti底层的Ti-N薄膜与不锈钢和高速钢基体之间界面的显微结构。在较厚Ti底层与不锈钢基体间的界面上有厚约20nm的FeTi界面层,Ti底层由具有[0001]取向的α-Ti相组成,TeTi相有[311]、[310]、[321]、[320]等几种择优取向。此外,较薄Ti底层与不锈钢基体间的界面比较光滑,界面层很薄。在基体温度为500℃时镀得的加Ti底层的Ti-N膜与高速钢基体的界面上,也观察到了Ti底层。它由细小的α-Ti晶粒组成,其中弥散分布着一些TiC的微小晶粒。在邻近膜/基界面的基体内断续分布着一些FeTi相的晶粒。在不加Ti底层的Ti-N膜与高速钢基体的界面上,观察到了TiN晶粒在基体中的碳化物MC(VC)上的外延生长,它们之间存在[310]_(vc)∥[100]_(TiN)的晶体学取向关系。与此类似,在高速钢中马氏体的晶粒上也外延生长出了TiN晶粒。在M_6C上生长的TiN初始晶粒很小,晶界不清晰。TiN与高速钢中碳化物和马氏体间的界面均较光滑,未观察到界面相。     

铝液析氢界面反应过程动力学研究

建立了铝液中氢的界面反应过程的数学物理模型，对界面反应过程进行了动力学推导和计算。利用铝液直接测氢装置对氢的界面反应动力学过程进行了测试。计算结果与测试结果基本吻合。     

环形管流量计测量气液两相流研究

提出了一种基于环形管流量计的新型气液两相流流量测量方法.设计了多圈环形管流量传感器,通过对多圈环形管的水平直径上和垂直直径上四个差压信号进行分析,建立了不同位置差压信号与总体积流量和总质量流量的关系模型,并由此获得气液两相流的混合密度,实现了气液两相流分相流量的测量.     

Axisymmetric Flow in an Oil Reservoir of Finite Depth Caused by a Point sink above an Oil-Water Interface

The flow of a stratified fluid (e.g., oil/water) withdrawn from a vertically confined porous medium through a point sink is considered. The withdrawal tends to cause the oil-water interface to move upwards. So long as the interface is below the well, the less dense fluid (oil) is pumped into the well without the denser fluid (water) until a critical flow rate is reached. The flow is considered to be axisymmetric, and involves a nonlinear boundary condition along the free surface. A boundary-integral equation method (BIEM) is used to find the interface position for different pumping rates. For small flow rates, a small-parameter expansion is derived and the results are compared with numerical solutions to the problem. There exists a critical withdrawal rate beneath which the water does not break through into the sink, this rate depending on the sink location and bottom geometry.     

Numerical simulation of unsteady cavitating flows using a homogenous equilibrium model

 Numerical simulations of two-dimensional cavity flows around a flat plate normal to flow and flows through a 90^∘ bent duct are performed to clarify unsteady behavior under various cavitation conditions. A numerical method applying a TVD-MacCormack scheme with a cavitation model based on a homogenous equilibrium model of compressible gas-liquid two-phase media proposed by the present authors, is applied to solve the cavitating flow. This method permits the simple treatment of the whole gas-liquid two-phase flow field including wave propagation and large interface deformation. Numerical results including detailed observations of unsteady cavity flows and comparisons of predicted results with experimental data are provided. Received: 5 August 2002 / Accepted: 6 January 2003     

基于流体诱发管道振动的气液两相流型识别

通过对不同流型的气液两相流流经管道时诱发的管道振动特性的实验研究,提出了基于流体诱发振动的非接触式在线两相流流型识别新方法.通过安装于测试管道外壁的振动传感器测量不同流型下气液两相流诱发的振动信号;采用小波包分析提取了表征流型变化的振动信号能量特征向量;以能量特征向量作为模型输入,建立了概率神经网络模型用于识别分层流、...     

倾斜状态下板翅式换热器封头物流分配特性的实验

海上平台受到海浪的作用会发生晃动和倾斜,从而影响板翅式换热器的入口物流分配特性。通过空气—水两相物流分配实验系统,分别进行封头结构水平状态和倾斜状态下的单相以及气液两相实验,获得不同实验工况下的封头物流分配特性,研究倾斜对封头物流分配的影响,从而为换热器的安装及工艺的改进提供依据。结果表明：水平状态下物流分配受惯性力的影响,不均匀度随雷诺数和气液比的增加而增大;倾斜状态下流体受到惯性力和重力的双重影响,物流分配均匀程度显著低于水平状态,倾斜角越大物流分配越不均匀,气液比越大物流分配受倾斜影响程度越大;固定封头或安装换热器时应严格保证其水平/竖直状态,或者通过液化工艺及换热器设计的改进消除倾斜的影响。     

基于阵列超声传感器的气液界面检测

利用超声波声束对两相流参数检测的优点,使用阵列超声传感器探究了气液界面下的超声波声束和液面的关系。实现了超声波声束对整个气液界面的参数检测,测量了静态气液界面高度,实现动态超声波声束对分层流气液界面的重构。并在河北大学多相流循环装置进行实验验证,实验结果表明,阵列超声波声束可以实现对气液界面高度检测,可分辨最小2mm气液界面高度;重构图像的截面含气率和高速相机拍摄得到的截面含气率误差不超过4%。     

Fully Stratified Particle-Laden Flow in Horizontal Circular Pipe

This article describes the results of an experimental measurement and visualization of coarse-grained fully stratified particle-water mixtures. This article focuses on the study of the carrier liquid velocity field and behavior and local velocities of conveyed particles. Glass balls and graded pebble gravel of 6 mm mean diameter were conveyed by water in a horizontal smooth pipe loop with a transparent pipe viewing section of inner diameter 40 mm. The measurements were performed in the smooth pipe and the pipe with rough stationary bed created by two layers of spherical particles of the same mean diameter as the conveyed particles. Particle movement along the pipe bottom was studied and the effect of the stationary bed on local velocity values of the carrier liquid and conveyed particles were evaluated. It was concluded that in the flow with stationary bed the maximum liquid velocity is markedly shifted from the pipe center to its top. The coarse-grained particles moved principally in a layer close to the pipe invert, for higher flow velocities particle saltation becomes the dominant mode of transport.     

Effect of pulsations on two-layer channel flow

The effect of vertical wall vibrations on two-phase channel flow is examined. The basic flow consists of two superposed fluid layers in a channel whose walls oscillate perpendicular to themselves in a prescribed, time-periodic manner. The solution for the basic flow is presented in closed form for Stokes flow, and its stability to small periodic perturbations is assessed by means of a Floquet analysis. It is found that the pulsations have a generally destabilizing influence on the flow. They tend to worsen the Rayleigh–Taylor instability present for unstably stratified fluids; the larger the amplitude of the pulsations, the greater the range of unstable wave numbers. For stably stratified fluids, the pulsations raise the growth rate of small perturbations, but are not sufficient to destabilize the flow. In the latter part of the paper, the basic flow for arbitrary Reynolds number is computed numerically assuming a flat interface, and the motion of the interface in time is predicted. The existence of a time-periodic flow is demonstrated in which the ratio of the layer thicknesses remains constant throughout the motion.     

Numerical modelling and flow visualization of mixing of stratified layers and rollover in LNG

A numerical model has been developed to study the mixing of two initially stratified layers which are subjected to a uniform lateral heat flux. An important distinction is made between the free surface and the liquid/liquid interface with regard to the different flow characteristics of the two layers. In the upper layer where warm liquid is cooled at the evaporating surface, the convective circulation is featured by a strong downward core flow; in contrast, the fluid flow in the lower layer is mainly confined to the wall boundary and is much weaker. Flow visualization experiments show that mixing of two stratified layers generally involves two stages in sequence: migration of the interface and rapid mixing between the remaining liquids. The interface movement is due to entrainment mixing at the interface. When the two layers approach density equalization, the interface becomes increasingly unstable and the core flow in the upper layer is able to break into the lower layer. The base to side heat flux ratio appears to be a major factor in determining the mode and intensity of the subsequent mixing at a rollover incident.     

Effect of stretching on interfacial stability

Summary. The effect of stretching on the stability of a horizontal interface between two fluids with different viscosities and densities is discussed. A local elongational flow acts to reduce the amplitude of perturbations and increase the wavelength of periodic waves, and thereby alter the instantaneous growth rate of disturbances. Linear stability analysis for Stokes flow reveals that, in the case of a horizontal interface between two semi-infinite fluids subjected to orthogonal stagnation-point flow, interfacial stretching is not able to suppress the Rayleigh-Taylor instability of unstably stratified fluids. In contrast, stretching is able to suppress the growth of periodic waves on the surface of a flat film resting on a horizontal surface. Numerical simulations based on the boundary-integral method for Stokes flow confirm that localized perturbations on the film surface are suppressed when the elongational flow is sufficiently strong.