A High-Resolution Resistive Probe for Nonlinear Analysis of Two-Phase Flows

Two-phase flow dynamics are highly complex, due to the strong coupling of various independent mechanisms and as demonstrated by the existence of a variety of flow patterns. The adoption of appropriate tools for nonlinear time series analysis tools may lead to a deeper insight in this complexity but requires high quality time series. This study describes a procedure appositely assessed in order to realise an impedance void fraction sensor of resistive type characterised by high-spatial and -temporal resolution. These characteristics have been accomplished through an appropriate geometrical design of the probe electrodes, aiming at obtaining a thin measurement volume so to improve the probe spatial resolution, and through the electronic assessment of the data acquisition system, improving its temporal resolution. A new calibration procedure has been also defined, based on an estimation of void fraction through a code for automatic extraction of bubble contours and the correction of image distortions.

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Influence of Inclination Angle on Intermittent Two Phase Flows

Volume 1B, Symposia: Fluid Mechanics (Fundamental Issues and Perspectives; Industrial and Environmental Applications); Multiphase Flow and Systems (Multiscale Methods; Noninvasive Measurements; Numerical Methods; Heat Transfer; Performance); Transport Phenomena (Clean Energy; Mixing; Manufacturing and Materials Processing); Turbulent Flows — Issues and Perspectives; Algorithms and Applications for High Performance CFD Computation; Fluid Power; Fluid Dynamics of Wind Energy; Marine Hydrodynamics ◽

10.1115/fedsm2016-7696 ◽

2016 ◽

Author(s):

Josep Escrig Escrig ◽

Buddhika Hewakandamby ◽

Georgios Dimitrakis ◽

Barry Azzopardi

Keyword(s):

Time Series ◽

Void Fraction ◽

Time Series Data ◽

Silicone Oil ◽

Wire Mesh ◽

Series Data ◽

Intermittent Flow ◽

Two Phase ◽

Cross Sectional ◽

Inclined Pipes

Intermittent gas and liquid two-phase flow was generated in a 6 m × 67 mm diameter pipe mounted rotatable frame (vertical up to −20°). Air and a 5 mPa s silicone oil at atmospheric pressure were studied. Gas superficial velocities between 0.17 and 2.9 m/s and liquid superficial velocities between 0.023 and 0.47 m/s were employed. These runs were repeated at 7 angles making a total of 420 runs. Cross sectional void fraction time series were measured over 60 seconds for each run using a Wire Mesh Sensor and a twin plane Electrical Capacitance Tomography. The void fraction time series data were analysed in order to extract average void fraction, structure velocities and structure frequencies. Results are presented to illustrate the effect of the angle as well as the phase superficial velocities affect the intermittent flows behaviour. Existing correlations suggested to predict average void fraction and gas structures velocity and frequency in slug flow have been compared with new experimental results for any intermittent flow including: slug, cap bubble and churn. Good agreements have been seen for the gas structure velocity and mean void fraction. On the other hand, no correlation was found to predict the gas structure frequency, especially in vertical and inclined pipes.

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Two-phase flow pattern classification based on void fraction time series and machine learning

Flow Measurement and Instrumentation ◽

10.1016/j.flowmeasinst.2021.102084 ◽

2021 ◽

pp. 102084

Author(s):

Jefferson dos Santos Ambrosio ◽

André Eugenio Lazzaretti ◽

Daniel Rodrigues Pipa ◽

Marco Jose da Silva

Keyword(s):

Machine Learning ◽

Time Series ◽

Flow Pattern ◽

Void Fraction ◽

Pattern Classification ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase

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Investigating the Effect of Pipe Inclination on Two-Phase Gas-Liquid Flows Using Advanced Instrumentation

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44239 ◽

2011 ◽

Cited By ~ 3

Author(s):

Abolore Abdulahi ◽

Lokman A. Abdulkareem ◽

Safa Sharaf ◽

Mukhtar Abdulkadir ◽

Valente Hernandez Perez ◽

...

Keyword(s):

Time Series ◽

Void Fraction ◽

Flow Rate ◽

Gas Flow ◽

Oil And Gas ◽

Silicone Oil ◽

Flow Characteristics ◽

Superficial Velocity ◽

Wire Mesh ◽

Two Phase

Pipes that make up oil and gas wells are not vertical but could be inclined at any angle between the vertical and the horizontal which is a significant technology of modern drilling. Hence, this study has been undertaken to look at the effect of inclination on flow characteristics especially at 10 degrees from both horizontal and vertical. Air/silicone oil flows in a 67 mm slightly deviated pipe have been investigated using advanced instrumentation: Wire Mesh Sensor Tomography (WMS) and Electrical Capacitance Tomography (ECT). They provide time and cross-sectionally resolved data on void fraction. Both the ECT probes and WMS were mounted on the inclined pipes upstream just at the point where flows were fully developed. By keeping the liquid flow rate constant at 10 litres/min (or liquid superficial velocity of 0.052m/s), gas flow rate was varied from 10 litres/min to 1000 litres/min (or gas superficial velocity from 0.05m/s to 4.7m/s). Then other values of liquid superficial velocity were considered. Visual observations were considered. Time series and void fraction were then measured for WMS while time series and liquid holdup were measured for ECT. The raw data were processed and then interpreted for proper analysis. From an analysis of the output from the tomography equipment, flow patterns were identified using both the reconstructed images as well as the characteristic signatures of Probability Density Function (PDF) plots of the time series of cross-sectionally averaged void fraction as suggested by some authors. Bubbly, slug and churn flows were observed for 10° from vertical pipe while bubbly, plug as well as slug flow when the pipe was inclined at 10° from horizontal. Examples of the PDFs are well illustrated which compares the use of ECT with WMS. In addition, statistical data such as Power Spectral Density (PSD), dominant frequency, mean void fraction as well as the structure velocities from cross correlation of the two planes of ECT have been identified.

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NONLINEAR DYNAMICS OF AIR-WATER MIXTURES IN VERTICAL PIPES: EXPERIMENTAL TRENDS

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127406016434 ◽

2006 ◽

Vol 16 (09) ◽

pp. 2749-2760 ◽

Cited By ~ 3

Author(s):

L. CANTELLI ◽

A. FICHERA ◽

I. D. GUGLIELMINO ◽

A. PAGANO

Keyword(s):

Time Series ◽

Phase Space ◽

Void Fraction ◽

Space Representation ◽

Two Phase ◽

Experimental Apparatus ◽

Experimental Time Series ◽

Impedance Sensor ◽

Analytical Tools

This study reports the results of the characterization of an air-water two-phase experimental apparatus and the preliminary analyses of the experimental time series. The test section of the apparatus consists of a vertical pipe equipped with an impedance void fraction sensor. The carrying frequency of the impedance sensor has been chosen in order to operate it as a resistive sensor. The calibration of the sensor has been performed through comparison of the instantaneous two-phase mixture conductivity signal and the local actual dimension of the bubble as estimated from high resolution photograph. The calibration curve allows, therefore, reliable estimation of the void fraction time series. A preliminary analysis of the time series has been performed both in time and frequency domains, evaluating also the time series autocorrelation. These analyses have pointed out the inadequacy of linear tools for the characterization of two-phase flow dynamics, which are nonetheless characterized by strong recurrence and autocorrelation, which need to be further exploited by mean of nonlinear analysis in phase space. Phase space representation of different typical flow patterns, corresponding to a succession of bifurcation, shows the high potential of nonlinear analytical tools, to be adopted in order to exploit the system dynamics.

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