Symbolic sequence statistical analysis of differential pressure measurement fluctuating signal of gas/liquid two-phase flow
The symbolic sequence statistical analysis method was applied to analyze two-phase flow measurement fluctuating signals and the key parameters affecting the symbolic statistical quantities were discussed.Based on the above study,eighty groups of differential pressure fluctuating signals of gas/liquid two-phase flow in vertical upward pipes were gathered and the statistical quantities of time irreversebility T_ fb and chi-square statistics χ 2 __ fb were extracted.When the gas superficial velocity was less than 0.02 m·s -1 ,the randomly variable motion features of bubble flow became stronger and the dynamic characteristics became relatively more complex with increasing gas superficial velocity.When gas superficial velocity exceeded 0.02 m·s -1 ,with increasing gas superficial velocity the flow pattern changed from bubble flow to slug flow and the dynamic characteristics became relatively simple,while with further increasing gas superficial velocity the flow pattern changed from slug flow to churn flow and the dynamic characteristics became more complex.This study showed that time irreversibility T_ fb and chi-square statistics χ 2 __ fb were sensitive statistical quantities characterizing gas/liquid two-phase flow pattern and the dynamic characteristics of gas/liquid two-phase flow pattern could be better understood by observing the change of these two statistical quantities with changing two-phase flow parameters.