垂直管内两相流流型的实验研究

为正确预测气井井筒气液两相流动规律,在多相流实验平台上开展了不同管径(28、60 mm)和不同压力(0.10、0.50 MPa)下空气/水两相流流型实验,利用高速摄像机再现了泡状流、段塞流、搅动流和环状流的流型结构和过渡现象,绘制了实验流型图,对比了管径、压力对流型过渡的影响以及分析了环状流形成与液滴夹带的关系,在气液两相流实验的基础上,以环状流形成过程为例,从流型的物理现象着手,对环状流形成的机理进行了定义和数学建模,从而建立了产液气井两相流流型转变组合机理模型。将该组合机理模型和不同管径、不同压力下的实验结果进行对比,发现新模型均能正确预测各流型间的转变条件,具有一定的通用性。     

螺旋管内油-水液液两相流流型

在两种不同放置位置螺旋管内进行了油 -水液液两相流流型的实验研究 ,定义了各种不同流动条件下油-水两相流的流型 ,给出了螺旋管内液液两相流的流型图 .进而讨论了各流型之间转变的机理 ,并考察了螺旋管结构尺寸及放置方式对油水两相流流型及相转变特性的影响 .     

非圆小通道内氮气-水气液二相流流型特性

通过可视化手段对水力直径为1.15 mm的矩形小通道(w×h=2 mm×0.81 mm)和正三角形小通道(边长2 mm)内氮气-水气液二相绝热垂直向上流动进行了实验研究.在表观气速0.1-30 m/s和表观液速0.01-5 m/s范围内,由实验结果得到2种小通道内的氮气-水典型流型图和流型转变界限.通过对比实验结果发现...     

垂直U型管两相流流型和传热研究——(Ⅲ)用管内扰流子消除U型管沸腾传热恶化的研究

为解决大型合成氨装置U型管高压废热锅炉爆管问题,在P=106×10~5Pa压力下试验了三种管内扰流子结构型式,对消除U型管沸腾传热恶化具有很好的效果.试验确定了三种扰流子型式的阻力特性,得出了单相阻力系数与雷诺数的关系特性,用Chisholm方程求得了两相流摩擦压降倍率与含汽率关系,建立了关联式.在水-空气试验台上进行了扰流子的流型观察试验,建立了流型图.试验得出单头扰流片阻力最小,结构简单,建议用于U型管废热锅炉消除传热恶化,以确保废热锅炉的安全运行.     

水平管内油水两相流流型转换特性

以高黏度的油和水为工质,在内径为25.7 mm,长52 m的水平不锈钢油水两相流实验环道内对油水两相流流型及其转换特性进行了实验研究.根据实验结果定义了不同流动条件下出现的流型,绘制了流型图.对影响油水两相管流流型转换的各种因素进行了综合分析,利用量纲分析的方法得出了流型转换的准则关系式,并提出了一个较为准确的有关油水两相管流中反相临界含水率的计算相关式.     

垂直U型管两相流流型和传热研究——(Ⅱ)U型管废热锅炉传热恶化

为查明垂直U型管废热锅炉爆管原因,在研究垂直U型管弯管段空气-水两相流流型转变的基础上,本文在高压电加热水回路试验装置上对其进行了热态试验研究,压力106×10~5Pa、质量流速800—2000kg/m~2·s、热负荷80—330kW/m~2.得出了沿U型管弯管段壁温分布特性.从两相流流型变化规律分析了U型管传热恶化的机理.根据热态试验结果修正了U型管两相流流型图.确定了U型管可靠操作条件.     

喷射器内气-液两相流流型及其转换特性的研究

利用平面激光诱导荧光(Planar Laser Induced Fluorescence,PLIF)技术,分析上喷式喷射器内气液两相流的流型及流型转换的特性.结果表明,在喷射器内气液两相首先形成喷射流,随着两相相互作用和动量传递,射流瓦解,气液两相随着气液比的不断增大分别形成泡状流、雾状流和块状流.根据实验结果绘制了喷射器上部射流瓦解后的气液两相流流型图.通过分析流型影响因素和流体力学特点,提出了流型转换的无因次关系式,并确定了各流型转换的具体表达式.     

倾斜管内两相流流型的实验研究

为了进一步了解倾斜向上管倾角对管内空气和水二相流流型转变的影响。本实验在两相流实验室进行,记录和总结实验数据,进而获得流型图。分析了空气-水形成两相流通过管长8 m,有机玻璃直径20 mm,分别将管倾斜5°,15°和25°,所得的数据采集。通过在相同管径条件下的倾斜管在不同倾斜角下流型出现的区域对比,得到管的倾斜角度对流型变化的影响。     

基于神经网络的两相流流型识别方法研究

采集了水平管内气水两相流动的差压信号,利用概率密度函数(PDF)对差压信号特征进行了分析;定义了PDF的四个特征参数,即PDF波峰个数K1、波峰峰值K2、波峰位置K3、以及PDF的方差K4来反映流型的特征。运用四个参数构成的特征向量对径向基函数(RBF)神经网络进行训练并识别流型,结果表明,该方法具有识别速度快、准确率高的特点,从而为两相流的流型识别提供了一种有效的手段。     

台阶式并行微通道内液液两相流流型及其转变机理

利用高速摄像仪研究了台阶式并行微通道内液液两相流流型及其转变机理。以甘油水为分散相、含3% Span 85的环己烷为连续相,观测到了滴状-滴状流、过渡-滴状流、喷射-过渡流和喷射-喷射流4种流型;以两相流量为坐标轴绘制了流型图,并获得了流型转变线;分析了流型的转变机理。考察了分散相黏度对流型及其转变的影响机制。随着分散相黏度的增大,流型转变线整体向下移动,滴状-滴状流区域变小,喷射-喷射流区域变大。最后,运用介尺度概念分析了并行微通道内液液两相流非均匀结构的动态效应。     

Flow pattern in horizontal and vertical two phase flow in small diameter pipes

New data on flow pattern transition for gas liquid flow in small diameter tubes (4 to 12 mm) is presented. The experimental results are compared with previously published models for horizontal and vertical flows considered to be valid for medium and large diameter pipes. The effect of surface tension which might be expected to be important in small diameter pipe flow has been found to affect only the stratified-slug transition in horizontal flow. A modification to the model to include this effect is proposed.     

Flow pattern boundaries during condensation: New experimental data

New experimental data on the flow patterns of condensing steam inside horizontal tubes of 13.4 and 25.3-mm i.d. are presented and discussed. Comparisons with flow pattern maps of adiabatic (gas-liquid) and condensing flows, as well as individual transition correlations, resulted in good agreements at the mist-annular and annular-wavy transitions. All of the horizontal flow pattern correlations tested failed in reasonably predicting the wavy-slug transition while the results of gas-liquid flow in upwardly inclined tubes appear to provide some explanation of the trend at this transition.     

The split of vertical two-phase flow at a small diameter T-junction

Measurements and observations of the phase split occurring at a small diameter vertical T-junction are reported. Time varying, void fraction data obtained using ring-type conductance probes have been analysed to yield valuable information regarding the effect of the junction on flow behaviour. It is shown through comparisons with the work of Stacey et al. [2000. The split of annular two-phase flow at a small diameter T-junction. International Journal of Multiphase Flow 26, 845-856] in a horizontal T-junction of a similar size that the orientation of the junction has no influence on the flow split. This behaviour is attributed to the absence of flooding and is corroborated by our high-speed images. Subsequently, better prediction of the phase split is obtained when the model of Azzopardi [1988. Measurements and observations of the split of annular flow at a vertical T-junction. International Journal of Multiphase Flow 14, 701-710] is modified to account for the absence of flooding. Regarding flow transitions, the methods by Barnea et al. [1983. Flow pattern in horizontal and vertical two-phase flow in small diameter pipes. The Canadian Journal of Chemical Engineering 61, 617-620] and Omebere-Iyari et al. [2005. Flow patterns for gas/liquid flow in small diameter tubes. Ninth UK National Heat Transfer Conference, Manchester, UK, 5-6 September] are found to give good predictions of the exit flow patterns in the horizontal side arm and vertical run arm, respectively.     

垂直管中管径突变对空气-水两相流流型的影响（Ⅰ）突缩接头

Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudden change in pipe diameter on flow patterns was analyzed. Flow pattern transition mechanisms were discussed and transition criteria for flow pattern transitions were deduced accordingly using the dimensional analysis.     

倾斜下降管内油气水三相流流型转变的实验研究

对倾斜下降管倾角变化对油气水三相流流型转变的影响进行了研究 ,通过大量实验得到流型图 ,发现倾角对流型转变有重大影响 :倾角增大到 3 0°时 ,增大气流量 ,泡状流已不再转变为间歇流 ,而是分层流 ;倾角变化对环状流和间歇流之间的转变影响显著。得到的界限方程规律与实验现象及流型图符合良好     

水基纳米流体在水平毛细管中的气液两相流流型特性

研究了在内径为1.6 mm的水平玻璃毛细管圆管内的氮气-氧化铜水基纳米流体的两相流流型分布图， 实验气体是氮气，实验液体是由去离子水、氧化铜纳米颗粒和十二烷基苯磺酸钠（SDBS）组成的悬浮液。首先对氮气-去离子水在水平毛细管内的两相流流型图进行了实验研究，将实验结果与前人提出的应用于常规管的半理论半经验公式进行了比较。然后在水中添加不同比容积的SDBS和氧化铜纳米颗粒制备成纳米流体，对纳米流体在水平毛细管内气液两相流的流型图进行了研究。结果表明，使用纳米流体后，毛细管内的分层波动流区域显著增加。纳米流体对两相流流型的影响主要是由添加表面扩散剂和纳米颗粒后降低了溶液表面张力产生的。纳米流体中的纳米颗粒和表面扩散剂浓度对流型图几乎无影响。     

Flow Structures of a Liquid Film Falling on Horizontal Tubes

Patterns of a liquid film falling across a vertical array of horizontal tubes change from droplet mode at low flow rates to liquid sheet at high flow rates. Between these limits, liquid columns form as a further stable flow pattern. The transition from one flow mode to another occurs via unstable structures consisting simultaneously of droplets and columns or of merging columns. The boundaries of the flow modes can be obtained from relationships expressing the flow rate as a function of physical properties, that is, the Reynolds number as a function of the Kapitza number. Correlations for the pattern boundaries recommended in the literature are compared with each other and found to be in acceptable agreement for practical purposes.     

Flow pattern transition in gas‐liquid downflow through narrow vertical tubes

The present report studies on the flow pattern transitions during vertical air water downflow through millichannels (0.83 ≤ Eötvös no. ≤ 20.63). Four basic flow patterns namely falling film flow, slug flow, bubbly flow, and annular flow are observed in the range of experimental conditions studied and their range of existence has been noted to vary with tube diameter and phase velocities. Based on experimental observations, phenomenological models are proposed to predict the transition boundaries between adjacent patterns. These have been validated with experimental flow pattern maps from the present experiments. Thus the study formalizes procedure for developing a generalized flow pattern map for gas‐liquid downflow in narrow tubes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 792–800, 2017     

流化床内部构件评选

在φ109mm流态化床里评选内部构件之后,在φ360mm流态化床里,通过邻二甲苯氧化制苯酐反应,以苯酐收率作为检验指标,对四种内部构件再次作了评选。获得的结果与以前是相同的,即斜片挡板效果最好,多孔板次之,垂直管束最不理想。但横向挡板与垂直管束联用时,效果与间隔小的横向挡板相当。回归方程指出,垂直管束构成的床层对温度和气速的敏感性较差,说明两者的气-固流动形态是不一样的。