水平管道油-气-水三相段塞流动持液率模型研究

油-气-水三相段塞流型持液率预测往往先将油水两相看作混合均匀的单相，再利用气液两相方法进行计算。这种方法适用于油水混合均匀的段塞流型。但在低气液相流速下，油-气-水三相段塞流型中有时油水是分离的，此时如果使用上述方法，可能导致比较大的误差。研究建立了分离假塞流型（油基和水基）的平均持液率计算新模型。统计分析发现新建模型与实验数据吻合很好。在实验的基础上，将油-气-水三相段塞流型划分为油基／分离／段塞流、油基／分散／段塞流、水基份离／段塞流、水基份散／段塞流四种。研究四种流型表明，在其他条件不变的情况下，对于气液两相流动和分散／段塞流型，持液率随着液相折算速度或液相黏度的增加而增加，随着气相折算速度的增加而减少。但对油基／分离／段塞流和水基／分离／段塞流，持液率则随着气相折算速度的增加，先上升后下降。     

气液两相水平管流分层--段塞流型转换机制研究

本文根据Stokes溃坝理论 ,提出了一个新的物理模型。通过对段塞单元的稳定性进行分析得出段塞保持稳定的临界液面高度值 ,从而得出分层流向段塞流转换的条件 ,并分析了液体粘度、管径大小对流型转换条件的影响。计算结果与实验值较为吻合     

水跃对水平管弹状流压力降的影响

本文对气、液两相分别应用一维形式的质量守恒方程和动量守恒方程。假设各流动物理量在水跃面上具有第一类间断点,推导出水平管弹状流中水跃压降的表达式。对以水和空气为流动介质,内径为２５．８ｍ,５１,２ｍｍ和３００ｍｍ的三种管道,在液相表观流速为１．１１ｍ／ｓ,气相表观流速为２￣１０ｍ／ｓ的范围内,计算出了水跃压降的大小随Ｌｏｃｋｈｒｔ－Ｍａｒｔｉｎｅｌｌｉ参数的变化关系,分析了水跃压降对水平管弹状流摩擦     

INFLUENCE OF SURFACTANT ON TWO-PHASE FLOW REGIME AND PRESSURE DROP IN UPWARD INCLINED PIPES

The influence of a surfactant on the two-phase flow regime and the pressure drop in upward inclined pipes is investigated for various gas/liquid flow rates.The air/water and air/100 ppm sodium dodecyl sulphate aqueous solution are used as the working fluids.The influence of the surfactant on the two-phase flow regime in upward inclined pipes is investigated using the electrical tomographic technique.For 0o,2.5o and 5o pipe inclinations,the surfactant has obvious effect on the transition from the stratified wavy flow to the annular flow,and the range of the stratified smooth flow regime is also extended to higher gas velocities.For 10o pipe inclination,no stratified flow regime is observed in the air/water flow.In the air/surfactant solution system,however,the stratified flow regime can be found in the range of and.For all inclination angles,the changes of the pressure gradient characteristics are accompanied with the flow pattern transitions.Adding surfactant in a two-phase flow would reduce the pressure gradient significantly in the slug flow and annular flow regimes.In the annular flow regime,the pressure gradient gradually becomes free of the influence of the upward inclined angle,and is only dependent on the property of the two-phase flow.     

EFFECT OF SURFACTANT ON TWO-PHASE FLOW PATTERNS OF WATER-GAS IN CAPILLARY TUBES

Flow patterns of liquid-gas two-phase flow were experimentally investigated. The experiments were carried out in both vertical and horizontal capillary tubes having inner diameters of 1.60 mm. The working liquid was the mixture of water and Sodium Dodecyl Benzoyl Sulfate (SDBS). The working gas was Nitrogen. For the water/SDBS mixture-gas flow in the vertical capillary tube, flow-pattern transitions occurred at lower flow velocities than those for the water-gas flow in the same tube. For the water/SDBS mixture-gas flow in the horizontal capillary tube, surface tension had little effect on the bubbly-intermittent transition and had only slight effect on the plug-slug and slug-annular transitions. However, surface tension had significant effect on the wavy stratified flow regime. The wavy stratified flow regime of water/SDBS mixture-gas flow expanded compared with that of water-gas.     

A MODEL FOR LIQUID SLUG LENGTH DISTRIBUTION IN VERTICAL GAS-LIQUID SLUG FLOW

The slug length and the trailing Taylor bubble velocity in an upward vertical slug flow were measured by using the optical probes and the EKTAPRO 1000 high speed motion analyzer. The correlation between the trailing bubble velocity and the length of liquid slug ahead of that bubble is derived from the experimental data. Based on this correlation as well as the bubble overtaking mechanism, a model for the slug length distribution at any designated locations along the pipe is proposed. The predicted results are in agreement with the experimental data.     

Prediction of oil-water flow patterns,radial distribution of volume fraction,pressure and velocity during separated flows in horizontal pipe

Flow of two immiscible fluids gives rise to variety of flow patterns,which influence transportation process.In this work,we present detailed analysis on the prediction of flow pattern maps and radial distribution of volume fraction,pressure and velocity of a pair of immiscible liquids through a horizontal pipeline by computational fluid dynamics(CFD) simulation using ANSYS FLUENT 6.3.Moderately viscous oil and water have been taken as the fluid pair for study.Volume of fluid(VOF) method has been employed to predict various flow patterns by assuming unsteady flow,immiscible liquid pair,constant liquid properties,and co-axial flow.From the grid independent study,we have selected 47 037 number of quadrilateral mesh elements for the entire geometry.Simulation successfully predicts almost all the flow patterns(viz.,plug,slug,stratified wavy,stratified mixed and annular),except dispersion of oil in water and dispersion of water in oil.The simulated results are validated with experimental results of oil volume fraction and flow pattern map.Radial distribution of volume fraction,pressure and velocity profiles describe the nature of the stratified wavy,stratified mixed and annular flow pattern.These profiles help to developing the phenomenological correlations of interfacial characteristics in two-phase flow.     

基于固液两相流模型的泥石流流速垂向分布研究

泥石流流速的垂向分布是泥石流运动理论中的核心问题之一。以固液两相流模型为基础,分析了泥石流中两相速度相等与不等条件下的本构关系和泥石流流速垂向分布的计算方法;在二维恒定均匀流的条件下,考虑两相之间的相互作用,推导层流和紊流流态下泥石流中液相和固相速度的垂向分布公式,并采用不饱和水石流的试验数据进行了验证。结果表明:泥石流两相之间的速度差异是描述两相之间相互作用的根本所在;泥石流固相浓度与本构关系中的模化参数均有关联,是流速垂向分布计算中的重要参量;基于两相流模型的泥石流流速垂向分布公式比现有公式更具普遍意义,且其计算结果能与试验数据较好吻合。     

INFLUENCE OF INCLINATION ANGLE ON THE MOTION OF TAYLOR BUBBLES IN UPWARD SLUG FLOW

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＳｌｕｇｆｌｏｗｉｓｏｎｅｏｆｔｈｅｍｏｓｔｃｏｍｐｌｉｃａｔｅｄｆｌｏｗｐａｔｔｅｒｎｓａｎｄｏｃｃｕｒｓｏｖｅｒａｗｉｄｅｒａｎｇｅｏｆｇａｓａｎｄｌｉｑｕｉｄｆｌｏｗｒａｔｅｓｉｎｓｍａｌｌａｎｄｍｅｄｉｕｍｓｉｚｅｔｕｂｅｓ .Ｉｔｉｓｃｈａｒａｃｔｅｒｉｚｅｄｂｙｌａｒｇｅｂｕｌｌｅｔ ｓｈａｐｅｂｕｂｂｌｅｓ (ｒｅ ｆｅｒｒｅｄｔｏａｓｔｈｅＴａｙｌｏｒｂｕｂｂｌｅｓ) ,ａｌｍｏｓｔｆｉｌｌｉｎｇｔｈｅｔｕｂｅ ,ｗｈｉｃｈａｒｅｓｅｐａｒａｔｅｄｂｙｌｉｑｕｉ…     

两相泥石流龙头的非恒定运动过程及能量特征

两相泥石流通常会出现高陡的龙头,其集中了大量的粗大卵石和砾石,呈现间歇性或波动性的运动。两相泥石流的运动除了取决于流体本身的流变特征外,液相和固相之间的能量传递也起到了重要作用,利用能量分析方法来研究两相泥石流固相、液相和龙头之间的能量转化机理是研究两相泥石流非恒定运动的有效途径。通过野外两相泥石流原型和水槽实验,研究其非恒定运动过程,结果表明,两相泥石流的龙头在泥石流起动初始阶段逐渐增长,当运动到一段距离后,趋于稳定。龙头高度和速度都有波动特征,通过能量分析建立了物理方程,分析证明两相泥石流龙头运动的平均速度正比于沟道的坡降和激发泥石流的洪水流量,反比于龙头的体积。     

Experimental study of flow patterns and pressure drops of heavy oil-water-gas vertical flow

A stainless steel apparatus of 18.5 m high and 0.05 m in inner diameter is developed, with the heavy oil from Lukeqin Xinjiang oil field as the test medium, to carry out the orthogonal experiments for the interactions between heavy oil-water and heavy oil-water-gas. With the aid of observation windows, the pressure drop signal can be collected and the general multiple flow patterns of heavy oil-water-gas can be observed, including the bubble, slug, churn and annular ones. Compared with the conventional oil, the bubble flows are identified in three specific flow patterns which are the dispersed bubble (DB), the bubble gas-bubble heavy oil, and the bubble gas-intermittent heavy oil (B_g – I_o). The slug flows are identified in two specific flow patterns which are the intermittent gas-bubble heavy oil (I_g – B_o) and the intermittent gas-intermittent heavy oil (I_g – I_o). Compared with the observations in the heavy oil-water experiment, it is found that the conventional models can not accurately predict the pressure gradient. And it is not water but heavy oil and water mixed phase that is in contact with the tube wall. So, based on the principle of the energy conservation and the kinematic wave theory, a new method is proposed to calculate the frictional pressure gradient. Furthermore, with the new friction gradient calculation method and a due consideration of the flow characteristics of the heavy oil-water-gas high speed flow, a new model is built to predict the heavy oil-water-gas pressure gradient. The predictions are compared with the experiment data and the field data. The accuracy of the predictions shows the rationality and the applicability of the new model.     

气液两相流压力波动特性

压力波动是两相流动的固有特性，研究波动规律对实现两相流动的智能监测有重要意义。本文采用统计学原理和确定性混沌学中的分形理论，对垂直上升空气水两相流的壁面静压力波动过程进行了研究，分析了表观液速对统计特征和分形特征的影响规律，首次发现环状流内高气速时压力波动的分维数大于1．5。     

油-水两相流流型转换研究

本文根据钢管内油—水两相流流型特征，建立了新的油—水两相管流流型的转换准则。它包括：分层流型的稳定性准则、分散流型和混合流型的转换边界及反相界线。流型转换准则得到了白油—水和柴油—水两相流的流型实验验证，而与有机玻璃管里的油—水两相流型的分布有一定的差异，这种差异与P．Angli的不同管材时的流型对比实验结论一致。这些都表明本文的流型转换准则能很好的预测钢管内的油—水两相流流型，这对于油田混钻管路的设计和运行具有十分重要的经济价值。     

入汇主河的泥石流龙头运动机理研究

作者基于野外观测资料和模型试验，提出了泥石流与主河交汇的两种模式，即：有上下分层交汇和无明显分层的潜入式交汇。建立了潜入式交汇的泥石流龙头运动方程，并讨论了模型参数的取值。计算结果得到以下结论：当主河水流费劳德数比较小(Fr＜0.35)时，入汇主河泥石流龙头在主河的运动速度近似以线性减速，且与试验值吻合较好；混合流粘滞系数和绕流系数对龙头运动速度影响较大；泥砂沉降速度对龙头内部体积比浓度有显著影响。     

竖直较大管径内气液两相流截面含气率实验研究

截面含气率是气液两相流动过程中的关键参数之一.在大管径流道内的气液两相流,弹状流难以形成,与常规通道相比,其流型特征明显不同.适用于常规通道截面含气率的一般计算方法,对于大管径流道而言,其适用性也较差.本文通过研究较大直径圆管内的气液两相流动过程,寻找适合于过渡尺寸流道内两相流动截面含气率的计算方法,从而建立起完整的、针对各个尺度范围内截面含气率的计算方法.实验选圆管直径为50 mm,介于常规通道和大通道之间;以空气和水作为工质,气相、液相折算速度的范围分别为0.05-2.0 m/s及0.01-2.0 m/s.首先利用获得的截面含气率实验数据,对适用于常规通道和大通道的截面含气率计算模型进行了评价;然后通过分析几类漂移流模型计算方法的分布系数和漂移速度的变化规律,解释了Hibiki-Ishii、Kataoka-Ishii、Kawanishi等几个模型计算误差较大的原因.     

微尺度流动界面现象及其流动边界条件分析

水平微尺度毛管中低Reynolds数流体流动出现许多另人费解的现象,如流动前缘并未出现Poiseuille速度剖面,而似一种“段塞式”流动,固/液界面看似不符合无滑移边界条件. 该文针对这些易引起困惑的问题,利用可视化微管流动实验及岩石孔隙仿真光刻模型流动实验,考察了润湿性对微尺度毛管中流体流动的影响,探讨了微尺度毛管中表面流动现象产生的实质.结果表明,在微尺度流动中观察到的小分子液体“段塞流动现象”,以及看似壁面滑移流动等现象,其实质是液/固壁面仍为无滑移边界,三相接触点以尤如运动的“坦克的链轨”发展方式,沿壁面发展,从而产生“段塞式”流动.虽然仍在低速层流的条件下,但由于界面张力的作用,接近动界面处流动质点的运动已不再保持一维直线运动.     

高浓度水流流速仪的研制与应用

作为一种复杂的固液两相流动，高浓度水流由于固体颗粒浓度高、颗粒级配宽及流动的可视性差等特点，致使其测流一直成为制约高浓度水流运动机理研究的瓶颈性问题。本文依据毕托管工作原理，通过液压传感方式感应测量高浓度水流动水压力和计算机数据采集处理等方法，成功地研制了新型感压式高浓度水流流速仪，并在室内天然沙与粉煤灰高含度水流试验中得到了应用。该流速仪研制成功为进一步研究高浓度水流流速分布规律、揭示其水流结构与输沙机理创造了有利条件。     

CHAOTIC HYDRODYNAMICS IN HORIZONTAL GAS-LIQUID BUBBLY FLOW

ＮＯＭＥＮＣＬＡＴＵＲＥｄ———ｅｍｂｅｄｄｉｎｇｄｉｍｅｎｓｉｏｎ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＣｄ(ｒ)———ｃｏｒｒｅｌａｔｉｏｎｓｕｍ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＮ———ｎｕｍｂｅｒｏｆｐａｉｒｓｏｆｐｏｉｎｔｓｏｎｔｈｅｒｅｃｏｎ ｓｔｒｕｃｔｅｄａｔｔｒａｃｔｏｒ,ｄｉｍｅｎｓｉｏｎｌｅｓｓｒ———ｓｃａｌｉｎｇｄｉｓｔａｎｃｅ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＤｃ ———ｃｏｒｒｅｌａｔｉｏｎｄｉｍｅｎｓｉｏｎ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＫ———Ｋｏｌｍｏｇｏｒｏｖｅｎｔｒｏｐｙ ,ｂｉｔｓ/ｓＲ…     

水平井筒变质量分散泡状流压降的理论与实验研究

由于水平井筒和常规水平管道中气液两相流动的相似和差别，可以预知常规水平管流的压降计算方法对于井筒流动来说就需要进行修正或扩展。本文对气、液两相分别应用质量守恒方程和动量守恒方程，考虑管壁存在人流或出流对于分层流流型压降的影响，得到水平井筒气液两相变质量流动分散泡状流流型的压降计算方法。同时，设计并建立了水平井筒流体流动模拟实验装置，在轴向为气液两相流动的前提下分别进行了上管壁单孔眼注入和下管壁单孔眼注入的压降实验研究，获得了大量的实验数据。实验数据和理论计算结果吻合很好，这表明该计算方法具有实际应用价值。     

虹吸管气液两相流压降特性试验

通过系列试验量测了不同安装高度、不同水位差时虹吸管水平管段的压降、含气率及过流量,探讨和分析了虹吸管气液两相流压降的变化规律及气液两相流流型不同时影响管道压降的因素。结果表明,气液两相流管道压降与液相满流时压降规律相同,即压降值随管道水头的增大而增大;但是,与液相有压管流不同,水位差一定时压降值随安装高度的增大而减小。当虹吸管内为气泡流时,气泡存在对沿程阻力系数λ影响很小,可忽略不计。管道实测压降小于计算值的原因是气液两相压降减小率等于流速减小率。当虹吸管内为过渡流和气团流时,气液两相压降减小率与流速减小率相差较大,实测压降的减小不仅与流速减小有关,含气率的大小对气液两相压降的影响也不可忽略,含气率的增大使气液两相流动阻力增大,即压降增大。