Statistical features of the flow evolution in horizontal liquid-gas slug flow

Rodrigues, Rômulo L.P.; Cozin, Cristiane; Naidek, Bruna Patricia; Neto, Moisés A. Marcelino; Silva, Marco J. da; Morales, Rigoberto E. M.

doi:10.1016/j.expthermflusci.2020.110203

Cited by 27 publications

(6 citation statements)

References 43 publications

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“…Distribusi probabilitas dari aliran slug tersebut didekati menggunakan distribusi bimodal. Sementara itu, investigasi fluktuasi beda tekanan untuk pola aliran slug di saluran horisontal berdiameter 24 mm dengan panjang 10 m dilakukan berbasis analisis fitur-fitur statistik seperti probability density function (PDF), autokorelasi dan power spectral density (PSD) [11]. Lebih lanjut, fitur-fitur statistik yang sama juga digunakan untuk menginvestigasi evolusi aliran di pipa horisontal berdiameter 25,8 mm [12] serta pipa vertikal berdiameter 20 mm dan panjang 90 cm [13].…”

Section: Pendahuluanunclassified

Pengaruh Rasio I/D terhadap Permulaan Flooding dan Fluktuasi Voltase Sinyal Tekanan Rezim Flooding pada Geometri Kompleks

Astyanto

Rahman

Medha

et al. 2021

JRM

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A nuclear power plant operation requires reliability safety systems. Therefore, an accidental scenario such as the LOCA becomes a specific attention. This relates to a countercurrent flow phenomenon which permits the occurrence of a flooding regime. This study aims to investigate the effets of I/D ratios of the riser on the onset of flooding and time-series voltage fluctuations of differential pressure signals of the flooding regime on a complex geometry representing a PWR hot leg. The test section contains a combination of a horizontal, an elbow and an inclined pipes. Three I/D ratios containing 1.9 (R1), 3.9 (R2) and 8.3 (R3) were assesed. The tabulated data are expressed in the term of a flooding curve. Meanwhile, the statistical features of the time-series voltage fluctuations of the signals are presented on both PDF and PSD graphs. The results obtained show that the assesed I/D ratios do not conduct significance effects on the onset of flooding. On the other hand, there are trends which can be obtained from the time-series signals with the increase of the I/D ratio. Those trends can also be observed in the such statistical features; the PDF and PSD graphs, respectively.

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Section: Pendahuluanunclassified

Pengaruh Rasio I/D terhadap Permulaan Flooding dan Fluktuasi Voltase Sinyal Tekanan Rezim Flooding pada Geometri Kompleks

Astyanto

Rahman

Medha

et al. 2021

JRM

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“…Recently, Rodrigues et al (2020) investigated the effect of superficial velocities on histogram distributions for bubble translational velocity and slug frequency in horizontal air-water slug flow. Qualitative description about the influence of the former on the latter were given.…”

Section: Horizontal Two-phase Slug Flow Experimental Studiesmentioning

confidence: 99%

Horizontal Air-Water Two Phase Slug Flow: Eulerian and Lagrangian Data Analysis

Chiarello¹,

Barros²,

Neto³

et al. 2020

Procceedings of the 18th Brazilian Congress of Thermal Sciences and Engineering

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Multiphase flows are recurrent phenomena both in natural environments-such as volcanic eruptions and blood flow through veins-and industrial environments-such as the nuclear and petroleum industries. Knowledge about the hydrodynamics of the flow as well as its evolution across the pipeline is essential to correctly design pipelines, equipments (such as pumps and slug catchers) and to formulate strategies to optimize the crude oil exploitation from reservoirs. A frequently reported flow pattern in oil pipelines is slug flow, reason why the present study focuses in its investigation. In order to analyze the flow, a novel methodology is proposed and applied to data retrieved in Multiphase Flow Center (NUEM) experimental facilities. The experimental loop has a length of 35.6 m and 26 mm internal diameter and was operated under 18 different slug flow conditionsvarying gas superficial velocity from 0.3 to 2.5 m/s and liquid superficial velocity from 0.3 to 3.0 m/s-across 5 different measuring stations composed by a pair of two-wire resistive sensors distributed along the pipe. Data was analyzed using Eulerian reference frame (ERF), which provides distributions for each hydrodynamic parameter in each measuring station for every experimental point, and Lagrangian reference frame (LaRF), which follows unit cells across the pipeline in order to evaluate the change in hydrodynamic parameters of single structures. Correlations were proposed based on retrieved results for hydrodynamic parameters average values and standard deviation. Moreover, a comparison against previous works was made in order to test the presented correlations as well as to propose corrections to the existing ones. Furthermore, details of the flow were investigated using the developed methodology, which was able to provide additional and insightful information about the flow behavior-such as the intrinsically unsteady nature of slug flow, as slug lengths were found to oscillate at all times, even though average values did not report significant changes, which would indicate developed flow conditions. Moreover, it was shown that gas expansion is a driver phenomenon in heavily aerated points, but becomes lees pronounced in low aeration flows-such as plug flows.

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“…Rodrigues et al. [8] investigated the characteristics of slug flow in two‐phase liquid‐gas flow using density probability functions. They investigated the functions of volume fraction density, bubble velocity, and velocity of each of the flow phases along the tube.…”

Section: Introductionmentioning

confidence: 99%

Computational modeling on slug flow phenomenon in inverted siphon and improving its performance

Aghebatie

Hosseini

2021

Z Angew Math Mech

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Slug flow is one of the flow patterns that occur in transmission systems containing two‐phase flow. Large air bubbles trapped in these systems block the flow and expose the structure to undesirable pressures and sharp fluctuations. In this research, numerical modeling has been performed using CFD technique in OpenFOAM software by InterFoam solver. Pressure fluctuations and their magnitude induced by slug flow in inverted siphon have destructive effects on the structure life. Combining the loads exerted by the pressure fluctuations induced on the structures with other loads may exceed the bearing loads of structure. In the inverted siphon, placing the ribs to reduce the damages exerted by slug flow were investigated. Different placements of ribs with different heights on the sloping parts of inverted siphon were modeled numerically. Study of flow characteristics showed that d/Hc ratio (d and Hc represent the rib height and duct height, respectively) can greatly balance the negative pressures and also improve the average pressures in the structure. The results showed that the use of ribs, the probability of forming slugs with pressure drop and severe fluctuations decreased and the maximum and minimum pressures improved about 25% and 20%, respectively.

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Statistical features of the flow evolution in horizontal liquid-gas slug flow

Cited by 27 publications

References 43 publications

Pengaruh Rasio I/D terhadap Permulaan Flooding dan Fluktuasi Voltase Sinyal Tekanan Rezim Flooding pada Geometri Kompleks

Pengaruh Rasio I/D terhadap Permulaan Flooding dan Fluktuasi Voltase Sinyal Tekanan Rezim Flooding pada Geometri Kompleks

Horizontal Air-Water Two Phase Slug Flow: Eulerian and Lagrangian Data Analysis

Computational modeling on slug flow phenomenon in inverted siphon and improving its performance

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