Impact of inlet gas turbulence on the formation, development and breakup of interfacial waves in a two-phase mixing layer

Jiang, Dianlu; Ling, Yue

doi:10.1017/jfm.2021.481

Cited by 14 publications

(14 citation statements)

References 58 publications

(126 reference statements)

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“…2022) or multimodal (Balachandar et al. 2020; Jiang & Ling 2021) distribution, when more than one formation process is involved. The log-normal and gamma distributions are expressed as and , respectively.…”

Section: Identification Of Atomization Patterns and Processesmentioning

confidence: 99%

“…In terms of the frequency ( f KH = u i /λ KH , where u i denotes the interfacial velocity), this scaling agrees with the trends in the measurements (Fuster et al 2013;Matas et al 2018), yet its absolute value differs by a factor of 2-3. The difference was addressed systematically by the inclusion of various factors, such as the momentum deficit (Matas, Marty & Cartellier 2011), the confinement of both phases (Matas 2015), surface tension (Matas et al 2018), spatiotemporal analysis (or the transition between the absolute and convective instability) (Fuster et al 2013), viscous effect (Otto et al 2013), and the turbulence intensity (Jiang & Ling 2021). While the waviness grows in amplitude downstream, its upstream side is exposed more to the gas flow, by which the liquid column is differentiated into multiple ligaments (figure 1a).…”

Section: Introductionmentioning

confidence: 99%

“…2013), viscous effect (Otto et al. 2013), and the turbulence intensity (Jiang & Ling 2021). While the waviness grows in amplitude downstream, its upstream side is exposed more to the gas flow, by which the liquid column is differentiated into multiple ligaments (figure 1 a ).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of liquid column atomization by annular dual-nozzle gas jet flow

2022

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The atomization of a water column by a gas jet flow (Reynolds number $\sim O(10^{4}\unicode{x2013}10^{5})$ ) issued from a two-stage annular nozzle is investigated experimentally. Varying the nozzle geometry, the momentum flux ratio of the upper and lower jets, and the water flow rate, we measure the processes of atomization with high-speed imaging, analysed analytically into four regimes. In the bulk atomization regime, the atomization is driven by the lower jet, but it is forced to occur earlier by the stronger upper jet before the water column reaches the lower jet in the droplet atomization regime. Interestingly, the size of the atomized droplets remains unaffected by the momentum flux ratio of upper to lower jets. The atomization process is governed by the Rayleigh–Taylor instability, by which the estimated droplet size agrees well with the measurement. In the backflow regime, a strong reverse flow is induced to force a substantial portion of atomized droplets to be drawn backward to the nozzle; a floating liquid column regime is captured transitionally, i.e. the column stagnates near the lower nozzle when the water flow rate is very low. To understand the mechanisms of each regime, the single-phase jet flow is measured separately using particle image velocimetry, and implemented into the control volume analysis with which we predicted analytically and validated the conditions for the occurrence of each regime. It is found that the acceleration of gas flow (velocity gradient) experienced by the falling water is the key parameter to drive the atomization.

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Section: Identification Of Atomization Patterns and Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of liquid column atomization by annular dual-nozzle gas jet flow

2022

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“…Comparisons of the numerical, experimental and theoretical results for the viscous shear instability are provided by Fuster et al (2013) and Matas (2015). Additionally, the gas-stream turbulence has been shown to affect the instability (Matas et al 2015;Jiang & Ling 2021). Although such works have delved deeper into various aspects of the instabilities, they have not yet led to the development of new models for the prediction of the droplet sizes in the spray.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic droplet atomization model (ADAM)

Jackiw

2023

J. Fluid Mech.

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The present work studies low viscosity twin-fluid atomization experimentally and analytically to characterize and predict the droplet size distribution of the spray. The study is based on experiments conducted using commercially available twin-fluid nozzles with water as the liquid. Shadowgraph images were used to visualize the near-nozzle flow while the droplet size distribution was measured in the far field using a Malvern Spraytec. To analytically model the atomization of the spray, the authors’ recent works on aerodynamic droplet breakup, which describe the formation and breakup of ligament and bag structures by multiple mechanisms, are extended to provide an analytical prediction of the droplet size distribution of the spray that is validated against the present experiments. The present model is developed to be a good physical representation of the spray behaviour at practical operating conditions. A Python implementation of the model has been deposited in a GitHub repository to accompany this work.

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“…We note that this is a simplified view; the Kelvin-Helmholtz instability is by definition inviscid, and the initial gas and liquid flows are steady and of infinite thickness. In the context of liquid jet breakup, the effects of viscosity were studied and discussed in Matas (2015), the effects of finite thickness in Bozonnet et al (2022), and the effects of unsteady gas turbulence in Matas et al (2015) and Jiang & Ling (2021).…”

Section: Introductionmentioning

confidence: 99%

Two-fluid coaxial atomization in a high-pressure environment

et al. 2022

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We study the dynamics of atomization of a liquid column by a coaxial gas flow with varying gas pressures. Specifically, we analyse how the gas density increase associated with elevated gas pressures in the ambient and co-flowing gas jet influences the liquid destabilization and breakup process, as well as the resulting droplet formation and dispersion. We present new experimental results for a coaxial liquid–gas atomizer operating in a high-pressure environment, with gas–liquid momentum ratio in the range $M = 5\unicode{x2013}56$ and pressurized gas densities $\rho _g/\rho _0 = 1\unicode{x2013}5$ , where $\rho _0$ is the ambient gas density at standard conditions. High-speed shadowgraphy images are used to quantify the spatially and temporally varying liquid–gas interface in the spray near-field. Liquid core lengths, spreading angles and other spray metrics are presented, and the influence of gas density is identified from the comparison with atomization at atmospheric conditions. In the spray mid-field, phase Doppler interferometry is used in conjunction with laser Doppler velocimetry to quantify the droplet size and velocities, as well as their radial variations across the spray. Results show an increase in droplet size at elevated ambient pressures, when keeping the gas–liquid momentum ratio constant. Finally, we show that these observations are in line with predictions from the Kelvin–Helmholtz and Rayleigh–Taylor instabilities, both of which are relevant to the gas–liquid atomization process.

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Impact of inlet gas turbulence on the formation, development and breakup of interfacial waves in a two-phase mixing layer

Abstract: Abstract

Cited by 14 publications

References 58 publications

Analysis of liquid column atomization by annular dual-nozzle gas jet flow

Analysis of liquid column atomization by annular dual-nozzle gas jet flow

Aerodynamic droplet atomization model (ADAM)

Two-fluid coaxial atomization in a high-pressure environment

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