SCI和EI收录∣中国化工学会会刊

›› 2010, Vol. 18 ›› Issue (5): 880-888.

• • 上一篇    

Multi-scale Chaotic Analysis of the Characteristics of Gas-Liquid Two-phase Flow Patterns

李洪伟1, 周云龙2, 孙斌2, 杨悦2   

  1. 1. North China Electric Power University, Beijing 102206, China;
    2. Northeast Dianli University, Jilin 132012, China
  • 收稿日期:2010-01-29 修回日期:2010-08-11 出版日期:2010-10-28 发布日期:2010-10-28
  • 通讯作者: ZHOU Yunlong,E-mail:ylzhou@mail.nedu.edu.cn
  • 基金资助:
    Supported by the National Natural Science Foundation of China (50976018);the Natural Science Foundation of JilinProvince (20101562)

Multi-scale Chaotic Analysis of the Characteristics of Gas-Liquid Two-phase Flow Patterns

LI Hongwei1, ZHOU Yunlong2, SUN Bin2, YANG Yue2   

  1. 1. North China Electric Power University, Beijing 102206, China;
    2. Northeast Dianli University, Jilin 132012, China
  • Received:2010-01-29 Revised:2010-08-11 Online:2010-10-28 Published:2010-10-28
  • Supported by:
    Supported by the National Natural Science Foundation of China (50976018);the Natural Science Foundation of JilinProvince (20101562)

摘要: Using the high-speed camera the time sequences of the classical flow patterns of horizontal gas-liquid pipe flow are recorded, from which the average gray-scale values of single-frame images are extracted. Thus obtained gray-scale time series is decomposed by the Empirical Mode Decomposition (EMD) method, the various scales of the signals are processed by Hurst exponent method, and then the dual-fractal characteristics are obtained. The scattered bubble and the bubble cluster theories are applied to the evolution analysis of two-phase flow patterns. At the same time the various signals are checked in the chaotic recursion chart by which the two typical characteristics (diagonal average length and Shannon entropy) are obtained. Resulting term of these properties, the dynamic characteristics of gas-liquid two-phase flow patterns are quantitatively analyzed. The results show that the evolution paths of gas-liquid two-phase flow patterns can be well characterized by the integrated analysis on the basis of the gray-scale time series of flowing images from EMD, Hurst exponents and Recurrence Plot (RP). In the middle frequency section (2nd, 3rd, 4th scales), three flow patterns decomposed by the EMD exhibit dual fractal characteristics which represent the dynamic features of bubble cluster, single bubble, slug bubble and scattered bubble. According to the change of diagonal average lengths and recursive Shannon entropy characteristic value, the structure deterministic of the slug flow is better than the other two patterns. After the decomposition by EMD the slug flow and the mist flow in the high frequency section have obvious peaks. Anyway, it is an effective way to understand and characterize the dynamic characteristics of two-phase flow patterns using the multi-scale non-linear analysis method based on image gray-scale fluctuation signals.

关键词: gas-liquid two-phase flow, gray-scale time series, empirical mode decomposition, Hurst exponent, chaotic recurrence plot

Abstract: Using the high-speed camera the time sequences of the classical flow patterns of horizontal gas-liquid pipe flow are recorded, from which the average gray-scale values of single-frame images are extracted. Thus obtained gray-scale time series is decomposed by the Empirical Mode Decomposition (EMD) method, the various scales of the signals are processed by Hurst exponent method, and then the dual-fractal characteristics are obtained. The scattered bubble and the bubble cluster theories are applied to the evolution analysis of two-phase flow patterns. At the same time the various signals are checked in the chaotic recursion chart by which the two typical characteristics (diagonal average length and Shannon entropy) are obtained. Resulting term of these properties, the dynamic characteristics of gas-liquid two-phase flow patterns are quantitatively analyzed. The results show that the evolution paths of gas-liquid two-phase flow patterns can be well characterized by the integrated analysis on the basis of the gray-scale time series of flowing images from EMD, Hurst exponents and Recurrence Plot (RP). In the middle frequency section (2nd, 3rd, 4th scales), three flow patterns decomposed by the EMD exhibit dual fractal characteristics which represent the dynamic features of bubble cluster, single bubble, slug bubble and scattered bubble. According to the change of diagonal average lengths and recursive Shannon entropy characteristic value, the structure deterministic of the slug flow is better than the other two patterns. After the decomposition by EMD the slug flow and the mist flow in the high frequency section have obvious peaks. Anyway, it is an effective way to understand and characterize the dynamic characteristics of two-phase flow patterns using the multi-scale non-linear analysis method based on image gray-scale fluctuation signals.

Key words: gas-liquid two-phase flow, gray-scale time series, empirical mode decomposition, Hurst exponent, chaotic recurrence plot