An Experimental Study on the Flow Characteristics of OilWater Two-Phase Flow in Horizontal Straight Pipes

The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superflcial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

水平微细圆管内R290流动沸腾流态可视化研究

本文对水平微细圆管内R290流动沸腾的流态进行了可视化研究,分析不同管径下流动沸腾换热主要流态形式及影响因素,基于理论流态图对比分析流态转变规律。实验工况:热流密度1~70 kW/m^(2),质量流率50~1020 kg/(m^(2)·s),饱和温度-10~25℃,管径1~3 mm,干度0~1。实验中共观察到8种R290微细通道内流动沸腾换热流态,其中间歇流和波状流为3 mm管的主要换热流态,弹状流和环状为1 mm管的主要换热流态;实测流态图中3 mm管的泡状流、混状流,2 mm管的泡状流,1 mm管的弹状流与D&W流态转变准则较为吻合,而2 mm管和1 mm管的离散流区域匹配性较差;管径的变化对流态有重要影响,随着管径的减小,气泡形状、流态形式、流态分布及流态转变曲线均发生变化,管径微尺度效应出现。

竖直矩形窄通道内水沸腾换热的流型研究

采用可视化方法观测了竖直矩形窄通道内单侧加热水的两相流型,发现主要有孤立气泡流,合并气泡流,搅拌流和环状流4种流型。与多数文献中类似工况的流型图对比,发现流型转变与通道宽深比、流体压力和加热条件有关。与现有的流型转变标准相比,大部分的流型转变界线都不能被很好的预测,因此有必要开发新的理论模型用于预测单面加热的窄通道内水和水蒸汽两相流型的转变标准。

矩形小尺度加热通道流型构成及过渡准则研究

基于可视化实验系统研究了矩形小尺度加热通道内主要流型构成,从微观角度深入研究气-液两相在流型过渡临界状态下的受力情况,构建了基于力学模型假定的流型过渡准则,并采用可视化实验数据对该模型进行了验证。结果表明,泡沫流-受限气泡流过渡准则预测准确度为93.94%,受限气泡流-环状流过渡准则预测准确度为94.07%,模型预测结果与实验数据基本吻合。