Experimental investigation of interfacial structures within churn flow using a dual wire-mesh sensor

Parsi, Mazdak; Vieira, Ronald E.; Torres, Carlos F.; Kesana, Netaji R.; McLaury, Brenton S.; Shirazi, Siamack A.; Schleicher, Eckhard; Hampel, Uwe

doi:10.1016/j.ijmultiphaseflow.2015.03.019

Cited by 51 publications

(13 citation statements)

References 38 publications

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“…More information on the velocity within the churn flow pipe is reported in Figure S2. The simulations show downwelling flow at the walls (Figures , S2a, and S2b), consistent with prior observations of churn flow (Laborde‐Boutet et al, ; Montoya et al, ; Parsi et al, ). One implication of churn flow is increased granularity in the holdup distribution compared to bubbly flow (Figure b versus Figure c), and thus resembling far more closely the DWH plume appearance (Figure a).…”

Section: Resultssupporting

confidence: 88%

Was the Deepwater Horizon Well Discharge Churn Flow? Implications on the Estimation of the Oil Discharge and Droplet Size Distribution

Boufadel

Gao

Zhao

et al. 2018

Geophysical Research Letters

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Improved understanding of the character of an uncontrolled pipeline flow is critical for the estimation of the oil discharge and droplet size distribution both essential for evaluating oil spill impact. Measured oil and gas properties at the wellhead of the Macondo255 and detailed numerical modeling suggested that the flow within the pipe could have been “churn,” whereby oil and gas tumble violently within the pipe and is different from the bubbly flow commonly assumed for that release. The churn flow would have produced 5 times the energy loss in the pipe compared to bubbly flow, and its plume would have entrained 35% more water than that of the bubbly flow. Both findings suggest that the oil discharge in Deepwater Horizon could have been overestimated, by up to 200%. The resulting oil droplet size distribution of churn flow is likely smaller than that of bubbly flow.

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Section: Resultssupporting

confidence: 88%

Was the Deepwater Horizon Well Discharge Churn Flow? Implications on the Estimation of the Oil Discharge and Droplet Size Distribution

Boufadel

Gao

Zhao

et al. 2018

Geophysical Research Letters

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“…Churn flow has the attributes of both slug and annular flows, however, there are no clear boundaries between the liquid and gas phases but there is the presence of waves and discontinuous gas cores. Some authors consider this type of flow to be fundamentally annular flow in nature with large disturbance waves carried by the gas flow 28,29 and just as in this study, huge waves in churn flow was also observed by Parsi et al 4,24 and Riva and Col. 10 Unlike the churn flow, there are clear and defined boundaries between the liquid and gas phases in Case 2 (Supplementary Figure 10(b)). The small bubbles between the two Taylor bubbles in Supplementary Figure 10(b) were also observed by previous researchers.…”

Section: Multiphase Flows In Double Elbow Geometriessupporting

confidence: 77%

“…The single elbow 3-D geometry in Figure 1(a) was modified to accommodate a second elbow as shown in Figure 1(b), and the normalized separation distance (L/D) between the two elbows mounted in series are 0, 5, 10, 15 and 20. The 3-D computational geometry in Figure 1(a) is similar to that of Parsi et al., 24 it consists of 3 m vertical and 1.9 m horizontal pipes, upstream and downstream of a standard 90-degree elbow respectively and the flow of fluids is from upward vertical to horizontal. Pipe diameter and the radius of curvature of elbow are 0.0762 m and 1.5 respectively.…”

Section: Numerical Modellingmentioning

confidence: 99%

“…Figure 7 shows the effect of the grid size on predicted cross-sectional averaged void fraction for the flow condition of superficial gas velocities (V sg ) of 10.3 m/s and superficial liquid velocity (V sl ) of 0.3 m/s at 1 m upstream of the elbow. Though it is difficult to ascertain mesh independency from the Figure 7, time averaged void fraction and its standard deviation have been compared with the experimental data of Parsi et al 24 Table 1 shows the mean void fraction and standard deviation of the times series of cross-sectional averaged void fraction. Meshes 1 and 2 produced similar averages while Mesh 3 produced an average higher than the experimental data.…”

Section: Mesh Sensitivity Studymentioning

confidence: 99%

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Computational fluid dynamics modelling of multiphase flows in double elbow geometries

Ogunsesan

Hossain

Droubi

2021

Proceedings of the Institution of Mechanical Engineers, Part E:

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This study investigates the effects of elbow on the transition and development of multiphase flow using computational fluid dynamics modelling techniques. The Eulerian - Multifluid VOF model coupled with an Interfacial Area Transport Equation has been employed to simulate air-water two-phase flow in a pipe with two standard 90 degree elbows mounted in series. Turbulence effects were accounted for by the RNG k-ε model. The effects of separation distance on two-phase flow development have been studied for initial slug and churn flow regimes. Computational fluid dynamics simulation results of phase distribution and time series of void fraction fluctuations were obtained and they showed good agreement with available experimental data. The results show that for initial slug flow regime, there is no flow regime transformation upstream and downstream of the two elbows. While at initial churn flow regime, flow regime transformation occurs at different sections of the flow domain before and after the two elbows. It was noticed that irrespective of the flow regime, the amplitudes and frequencies of void fraction fluctuation become smaller as the fluid flows along the pipe. Changes in the separation distance between the two elbows have larger effects on the flow at churn flow regime.

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“…As the gas flow increases to 50% per volume and if the pipe's diameter is larger than approximately 0.1 m (Kytömaa & Brennen, 1991), the pattern becomes that of churn flow (Orell & Rembrand, 1986), where the gas and liquid are no longer coflowing rather tumbling within the pipe. In this regime, one observes sporadic “flooding” of the pipe, which is a situation where a part of the liquid on the wall is transported upward while appearing highly disturbed, and another part flows downward (Govan et al, 1991; Parsi et al, 2015a). Churn flow results also in the manifestation of various instabilities at the gas‐liquid interface.…”

Section: Hydrodynamics Within the Conduit Or The Wellmentioning

confidence: 99%

A Review on Multiphase Underwater Jets and Plumes: Droplets, Hydrodynamics, and Chemistry

Boufadel

Socolofsky

Katz

et al. 2020

Reviews of Geophysics

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Jets and plumes have been the focus of quantitative investigations since the mid‐1950s. These investigations intensified following the Deepwater Horizon oil spill, in which thousands of tons of oil and natural gas were released into the Gulf of Mexico. This review focuses on plume dynamics that apply to both single‐phase and multiphase liquid‐in‐liquid and liquid plus gas into liquid plumes, including bubble and droplet formation, and heat and mass transfer. Broadly, our work highlights several previously unknown or overlooked aspects of multiphase flow in the deep oceans. Upstream of the jet release, multiphase hydraulics can significantly affect the turbulence, for instance, through churn flow that enhances the turbulence in the free jet, affecting the conditions where bubbles and droplets are formed. Droplet formation was a major focus recently, with experiments covering a range of scales and flow rates of oil and gas at low and high pressure. Detailed observations of droplet formation at the jet‐water boundary reveal the formation of compound droplets, which are emulsions of oil and water with implications for mass conservation and mass transfer. At the plume scale, integral models have been adapted to include the complex thermodynamics and chemistry of oil and gas plumes. In parallel, significant advances were made in numerical simulations of multiphase plumes through large eddy simulations by treating the oil and gas either a continuous or discrete phase. Through this work, a vivid picture of the complex droplet, chemical, and hydrodynamic behavior of multiphase plumes in the ocean is emerging.

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Experimental investigation of interfacial structures within churn flow using a dual wire-mesh sensor

Cited by 51 publications

References 38 publications

Was the Deepwater Horizon Well Discharge Churn Flow? Implications on the Estimation of the Oil Discharge and Droplet Size Distribution

Was the Deepwater Horizon Well Discharge Churn Flow? Implications on the Estimation of the Oil Discharge and Droplet Size Distribution

Computational fluid dynamics modelling of multiphase flows in double elbow geometries

A Review on Multiphase Underwater Jets and Plumes: Droplets, Hydrodynamics, and Chemistry

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