Study on Multi-Scale and Double Fractal Characteristics of Gray Pulse Signals in Gas-Liquid Two-Phase Flow Images

Dynamic image videos of three typical flow patterns have been taken by a high speed camera in the horizontal tube of the gas-liquid two-phase flow.The average gray scale of each frame of the pulse signals is extracted,which decomposed by the multi-scale intrinsic mode function.Combined with R/S analysis method,the HURST exponent of each scale and double fractal characteristics is extracted.Two forms of the dynamic behavior of the bubbles and the single bubble are analyzed,which belong to the three typical gas-liquid two-phase flow patterns.The results are checked by extracting the kurtosis coefficient,and the variation of HURST exponent with the increase of the gas apparent velocity is discussed.The results show that the EMD decomposition combined with the R/S analysis can commendably reveal the nonlinear kinetic characteristics of gas-liquid two-phase flow.