油气水三相流流型的灰度波动时间序列分析

三相流流型极大地影响三相流的流动和传热特性,准确表征流型对相关设备的设计和运行具有重要意义。在水体积流量为1.32—12.15 m3/h,油体积流量为0.01—0.43 m3/h,空气体积流量为0.75—2.5 m3/h时,对垂直上升管中油气水三相流的6种典型流型进行了动态图像的拍摄,提取每一帧图像的灰度均值组成灰度波动信号,进行了分形及混沌时间序列分析。分析结果为:当空气流量在0.75—2.5 m3/h之间变化时,所提取的分形维数及吸引子关联维数分别在0.924 7—1.223 4及1.493 7—5.498 2之间,且分形维数及混沌吸引子关联维数随气相流量呈不规则突变,并与流型的Wigner-Ville分布(WVD)特征相对应,表明了分形维数及混沌吸引子关联维数对油气水三相流流型变化具有敏感的"指示器"特性,可以较好地表征油气水三相流流型变化。

Time series analysis of image gray fluctuating signals of oil-gas-water three-phase flow patterns

Three-phase flow and heat transfer character are extremely influenced by the flow regimes,and the accurate identification of flow regimes is important for the operation and design of interrelated instruments.Within water flow rate of 1.32-12.15 m3/h,oil volume flow rate of 0.01-0.43 m3/h,air volume flow rate of 0.75-2.5 m3/h,the dynamic images of six typical flow patterns of the oil-gas-water three-phase flow were taken with high-speed camera in the vertical upward pipe.The fractal and chaotic time series was analyzed by extracting the gray averages from each frame image to form the image gray-scale fluctuating signals.The analysis result shows that when the air flow rate is changed between 0.75 m3/h and 2.5 m3/h,the fractal dimension and attractor correlation dimension are ranged respectively from 0.924 7 to 1.223 4,and from 1.493 7 to 5.498 2.Both fractal dimension and chaotic attractor correlation dimension show an irregular sudden change with gas flow rate,which accords with Wigner-Ville distribution(WVD) characteristics of flow patterns.It indicates that the fractal dimension and chaotic attractor correlation dimension are sensitive to flow pattern variation as an "indicator",and can characterize the variation of oil-gas-water three-phase flow patterns.