Chaotic Characteristic Analysis of Conductance Signals of Gas/Liquid Two Phase Flow in Vertical Upward Pipe

Abstract

AbstractIn this paper, firstly the Lorenz chaotic equation was taken as an example to produce a nonlinear time series, and we discussed the applicability of delay time algorithm to the presence of noise at different time series length. The study shows that the C‐C algorithm of delay time is robust, and the Fraser et al's mutual information algorithm and auto‐correlation function algorithm are affected by presence of noise and variations of time series length and the Libert et al's mutual information algorithm can not calculate the delay time. Based on the above studies, we characterized the gas/liquid two phase flow patterns based on the chaotic analysis of conductance fluctuating signals. The results indicate that at a low superficial water velocity, with increasing superficial gas velocity, the dynamic characteristic of bubble and churn flows becomes more complex, and the slug flow is affected by the liquid superficial velocity; whereas at high superficial water velocity, with increasing superficial gas velocity, the dynamic characteristic of gas/liquid two phase flow becomes simpler while the flow pattern changes from bubble flow to slug flow, and the dynamic characteristic of slug flow shows unsteady fluctuating phenomena due to liquid phase turbulence interaction, and the dynamic characteristic of two phase flow becomes more and more complex while the flow pattern changes from slug to churn flow. The study shows that we can characterize the flow pattern variations of gas/liquid two phase flows based on the chaotic analysis of conductance signals, it is a useful tool to understand flow pattern transition mechanism and its dynamic evolution characteristic.