Multi-Scale And Nonlinear Characteristic Analysis Of Gas/Liquid Two-Phase Flow Structure

In this paper, the conductance fluctuating signals of gas/liquid two-phase flow are processed by wavelet analysis method and recurrence analysis method, which could explain the dynamic character of two-phase flow patterns in view of multi-scale and nonlinear analysis. The results indicate that recurrence plots of different scale signals reflect the dynamic structure characters of gas/liquid two-phase flow from low band to high band. Five typical flow patterns all take on better recurrence nature and recurrence plots represent development line texture structure in low band. However, the different flow patterns behave different features in high band recurrence plots. The rectangle massive texture appears in slug flow recurrence plots because of its periodicity, and stochastic movement of bubble flow and churn flow becomes stronger with the frequency increasing, so isolated points distribute in high band recurrence plots stochastically. And then, the dynamic structure characters of different flow patterns on each scale can also be obtained by analyzing the rules of three measures of recurrence characteristic with the gas superficial velocity increasing. Hence, the multi-scale analysis is a powerful tool to characterize the dynamic movement of two-phase flow from macro scale to micro scale.Moreover, the experiment data are also researched by the complexity measure method. And the results show that the Lempel and Ziv complexity,spectrum entropy and approximate entropy are sensitive to the flow pattern transition in gas/liquid two-phase flow. The dynamics structure characteristics of gas/liquid two-phase flow patterns can also be revealed by analyzing the rules of three complexity measures changing with gas/liquid two-phase flow parameters. There are commendably corresponding relations between complexity measures and recurrence quantification analysis eigenvalues. It indicates the complexity measures provide efficient, assistant and diagnosable tools to comprehend the flow patterns transition mechanism of gas/liquid two-phase flow.