Statistical characteristics of differential pressure fluctuations and flow patterns of gas-liquid two-phase flow in an inclined pipe.

In the present work, an objective method to characterize two-phase flow pattern was developed and implemented. The method is based on the characteristics of the signals provided by transducers measuring local temperature and pressure plus the intensity of a laser beam crossing the two-phase flow. The statistical characteristics of these signals were used as input features for the k-means clustering method. In order to implement the method, experimental flow patterns were obtained during flow boiling of R245fa in a 2.32 mm ID tube. Experiments were performed for mass velocities from 100 to 700kg/m2s, saturation temperature of 31 °C and vapor qualities up to 0.99. The cluster classification was compared against flow patterns segregated based on high speed camera images (8000 images/s) and a reasonable agreement was obtained.

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Application of Chaos Theory in Identification of Two-Phase Flow Patterns and Transitions in a Small, Horizontal, Rectangular Channel

Journal of Fluids Engineering ◽

10.1115/1.2817390 ◽

1996 ◽

Vol 118 (2) ◽

pp. 383-390 ◽

Cited By ~ 35

Author(s):

Y. Cai ◽

M. W. Wambsganss ◽

J. A. Jendrzejczyk

Keyword(s):

Chaos Theory ◽

Two Phase Flow ◽

Rectangular Channel ◽

Pressure Fluctuations ◽

Fractal Dimensions ◽

Flow Patterns ◽

Deterministic System ◽

Phase Flow ◽

Two Phase ◽

Measurement Tools

Various measurement tools that are used in chaos theory were applied to analyze two-phase pressure signals with the objective of identifying and interpreting flow pattern transitions for two-phase flows in a small, horizontal rectangular channel. These measurement tools included power spectral density function, autocorrelation junction, pseudo-phase-plane trajectory, Lyapunov exponents, and fractal dimensions. It was demonstrated that the randomlike pressure fluctuations characteristic of two-phase flow in small rectangular channels are chaotic, and governed by a high-order deterministic system. The correlation dimension is potentially a new approach for identifying certain two-phase flow patterns and transitions.

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Measurement for Individual Gas-Liquid Two-Phase Flow Rates Based on Stochastic Features of Differential Pressure Fluctuation

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37470 ◽

2007 ◽

Author(s):

Tomomi Uchiyama ◽

Hirokazu Tominaga ◽

Kiyoshi Minemura

Keyword(s):

Two Phase Flow ◽

Pressure Fluctuations ◽

Vortex Generator ◽

Measuring Method ◽

Differential Pressure ◽

Phase Flow ◽

Two Phase ◽

Flow Rates ◽

Individual Phase ◽

The Individual

This study proposes a measuring method for the individual phase flow rates of gas-liquid two-phase mixtures flowing through a pipe. First, the time-variations for pressure are measured at three points around a vortex generator mounted in the pipe under the known flow rates. Secondly, the stochastic features of the differential pressure fluctuations, such as the mean and the standard deviation, are calculated to construct a database relating the flow rates with the stochastic features. Consequently, if the differential pressure fluctuations are measured under unknown flow rates, the individual phase flow rates are successfully identified from the database. A neural network is employed for the identification. This study also applies the proposed method for the measurement of air-water two-phase flow and discusses the measured results.

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