Experiments on void fraction waves

Saíz-Jabardo, José Maria; Bouré, J. A.

doi:10.1016/0301-9322(89)90048-7

Cited by 38 publications

(17 citation statements)

References 7 publications

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“…[16]), versus the Taylor bubble velocity obtained by the cross-correlation technique, as seen in Eq. (15). From the graphics, one can see that a reasonable agreement exists.…”

Section: Flow Regime Identificationmentioning

confidence: 56%

“…One of the earliest multipleelectrode impedance sensors was analyzed by Merilo et al [12], who tested a rotating electrical field applied to a six-electrode sensor configuration promoting an improvement in flow signal. Later, other studies were carried out in connection with the determination of instantaneous signal response to void fraction wave propagation [13][14][15]. Electrical impedance tomography is a modern technique that has brought some considerable advances and demonstrates a two-phase flow reconstruction principle based on signals of many flush mounted electrodes [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Void Fraction Measurement and Signal Analysis from Multiple-Electrode Impedance Sensors

Rocha

Simões-Moreira

2008

Heat Transfer Engineering

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Void fraction sensors are important instruments not only for monitoring two-phase flow, but for furnishing an important parameter for obtaining flow map pattern and two-phase flow heat transfer coefficient as well. This work presents the experimental results obtained with the analysis of two axially spaced multiple-electrode impedance sensors tested in an upward air-water two-phase flow in a vertical tube for void fraction measurements. An electronic circuit was developed for signal generation and post-treatment of each sensor signal. By phase shifting the electrodes supplying the signal, it was possible to establish a rotating electric field sweeping across the test section. The fundamental principle of using a multipleelectrode configuration is based on reducing signal sensitivity to the non-uniform cross-section void fraction distribution problem. Static calibration curves were obtained for both sensors, and dynamic signal analyses for bubbly, slug, and turbulent churn flows were carried out. Flow parameters such as Taylor bubble velocity and length were obtained by using crosscorrelation techniques. As an application of the void fraction tested, vertical flow pattern identification could be established by using the probability density function technique for void fractions ranging from 0% to nearly 70%.

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“…[16]), versus the Taylor bubble velocity obtained by the cross-correlation technique, as seen in Eq. (15). From the graphics, one can see that a reasonable agreement exists.…”

Section: Flow Regime Identificationmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Void Fraction Measurement and Signal Analysis from Multiple-Electrode Impedance Sensors

Rocha

Simões-Moreira

2008

Heat Transfer Engineering

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“…Because of the severe slippage effect and non-uniform phase distribution in gas-water flows, the establishment of models is challenging. For the mixture velocity measurement, the fact that the cross-correlation velocity corresponds to the kinematic wave velocity in the multiphase flow [ 34 , 35 ] has been found, and the mixture velocity measurement model can be reasonably established based on this theory [ 36 , 37 ]. Based on the work of Lucas and Jin [ 36 ], the relationship between cross-correlation velocity U cc and mixture velocity in annular space U m1 in two-phase flows can be expressed as:

…”

Section: Resultsmentioning

confidence: 99%

Salinity Independent Flow Measurement of Vertical Upward Gas-Liquid Flows in a Small Pipe Using Conductance Method

Wang

Jin

Zhai

et al. 2020

Sensors

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Flow measurement in gas-liquid two-phase flow is always a challenging work, because of the non-uniform phase distribution, severe slippage effect between phases, and different flow structures. Furthermore, the variation of salinity changes the water conductivity, which brings more difficulties to multiphase flow measurement. In this study, a methodology for flow measurement using the conductance method in gas-liquid two-phase flow with salinity change is proposed. The methodology includes the suitable conductivity detection method, the strategy of using combined sensors, and the measurement models of flow parameters. A suitable conductivity detection method that can guarantee that the sensor output is linearly proportional to the conductivity is proposed. This conductivity detection method can ensure that the sensors have a high and constant resolution in the conductivity variation caused by water holdup under the conditions of water conductivity change. Afterward, a combined sensor system consisting of a water holdup sensor, velocity sensor, and water conductivity sensor is designed and experimentally evaluated in gas-water two-phase flow in a 20 mm inner diameter pipe. Considering the non-uniform phase distribution, severe slippage effect between phases, different flow structures, and the variation of salinity, a new water holdup measurement model and flow velocity measurement models are established to achieve salinity independent water holdup measurement and flow velocity measurement for the first time.

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“…Some experimental data on bubbly air -water flow are available for the model assessment [13,17,18,37,38]. In Figures 4 and 5 respectively, the results of analytical solution with interfacial tension effects (Equation (43)) in explicit form and previous models are compared with experimental data on void propagation from Mercadier [17] and Bernier [18].…”

Section: Void Wa6e Propagationmentioning

confidence: 99%