Symbolic sequence analysis method of gas/liquid two-phase flow measurement fluctuation signals

Symbolic sequence analysis method was applied to analyze two-phase flow measurement fluctuating signals and some issues about key parameters which were effect on the symbolic statistical quantities were discussed. Based on the above study, we gathered eighty groups differential pressure fluctuating signals of gas/liquid two-phase flow in vertical upward pipes and extracted the time irreversibility and chi-square statistics. When the gas superficial velocity is less than 0.02 m/s, the random variable motion feature and the dynamic character of bubble flow become gradually complex with the gas superficial velocity increasing. When gas superficial velocity exceeds 0.02m/s, the dynamic character of flow pattern evolution becomes gradually simple from bubble flow to slug flow and the dynamic character becomes more and more complex from slug flow to churn flow with the gas superficial velocity increasing. This study shows that time irreversibility and chi-square statistics are sensitive feature quantities of characterizing gas/liquid two-phase flow patterns and we can better understand dynamic character of gas/liquid two-phase flow patterns by observing the two statistical quantities changing with the two-phase flow parameters.