| Multiphase flow widely exists in nature as well as in the process of modern industrial production in China.It affects our living environment and relates to the modern industrial production.Exploring and realizing the high efficiency and precision of the two-phase or three-phase flow detection method has become a hot spot of modern industrial nations and belongs to be one of the national and international problems to be solved.Two-phase flow detection is mainly include direct observation and using traditional instrument.Acoustic emission technique is a kind of nondestructive testing technology without breaking the pipe itself for two-phase flow measurements and direct contact,and not interfering with the fluid flow itself.It can realize on-line monitoring,using four symmetrical probes installed on the experimental pipeline and simultaneously acquiring signals.It is mainly used for four kinds of typical vertical rising pipe flow pattern(bubble flow,slug flow,foam flow and annular flow).Through the analysis of the flow of time domain noise figure,it can be intuitive to distinguish the characteristics of different flow patterns.In this paper,using the acoustic emission technique for two-phase flow to acquire noise signals and the use of Fourier transform to realizing the conversion of flow noise signals from the frequency domain to time domain.Results showed that the horizontal and vertical contrast between different flow pattern indicating that the frequency spectrum of the signal can’t distinguish between different flow pattern and at the same time it also has no way to express the characteristics of transition between flow patterns.Correlation dimension method using different flow patterns were analyzed.Studies indicate that the correlation dimension dynamic characteristic flow pattern transition phase of the system has become consistent with the dynamic characteristics of annular flow.Correlation dimension of annular flow gap has lager difference with other flow patterns. |
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