Synchrotron radiography characterization of the liquid core dynamics in a canonical two-fluid coaxial atomizer

Machicoane, Nathanaël; Bothell, Julie; Li, Danyu; Morgan, Timothy B.; Heindel, Theodore J.; Kastengren, Alan L.; Aliseda, Alberto

doi:10.1016/j.ijmultiphaseflow.2019.03.006

Cited by 42 publications

(39 citation statements)

References 17 publications

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“…An open-source two-fluid coaxial atomizer * designed to study atomization physics in a canonical setting (Machicoane et al, 2018) is used in this experimental implementation of real-time feedback control of a spray. The design produces reproducible laminar liquid and turbulent gas streams that have been characterized extensively (Machicoane et al, 2019). The liquid is injected through a straight circular duct and the condition of the liquid going into the atomization is fully-developed laminar Poiseuille flow.…”

Section: Atomizer and Flow Loopmentioning

confidence: 99%

Feedback Control of Coaxial Atomization Based on the Spray Liquid Distribution

et al. 2019

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We demonstrate a novel implementation of real-time feedback control on the structure of the spray produced by a two-fluid coaxial atomizer. The ratio of angular to longitudinal gas flow rates, called swirl ratio, as well as the total amount of gas coflow are used as the actuation at the nozzle. The swirling and swirl-free gas flow rate are individually set by the control algorithm, with the control objective set based on an optical absorbance radial profile that is related to the liquid volume fraction across the spray. We analyzed the liquid volume fraction profiles measured in open loop by means of singular value decomposition and principal component analysis (PCA) and found that the different states of the spray across a wide range of operating conditions can be described with fidelity by three principal components. The control algorithm maps the resulting state PCA projections to the control variables. Real time control of the spray is achieved over a wide range of operating conditions (gas-to-liquid momentum 1 − 20 and swirl ratios 0 − 1).

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Section: Atomizer and Flow Loopmentioning

confidence: 99%

Feedback Control of Coaxial Atomization Based on the Spray Liquid Distribution

et al. 2019

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“…The two-fluid coaxial atomizer  used in this research has been designed to be an open source canonical atomizer that can be reproduced in any laboratory experiment or numerical simulation that aims to compare or validate data against that obtain in this study or others published with this system (Machicoane et al, 2019;Huck et al, 2018). As Figure 2 suggests, liquid and gas enter the atomizer separately and flow parallel to each other at the nozzle exit.…”

Section: Methodsmentioning

confidence: 99%

Time-Averaged Spray Analysis in the Near-Field Region Using Broadband and Narrowband X-Ray Measurements

Bothell

Morgan

et al. 2019

Atomiz Spr

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The characterization of a spray in the near-field region is challenging because of its high optical density in this region. X-ray based techniques, with weak scatter and strong penetration properties, can provide better characterization than optical assessment techniques in this region.In this work, the effects of various operating parameters on the evaluation of the optical depth (defined as the accumulated liquid thickness in the beam path times the X-ray attenuation coefficient) and spray profile of an atomizing spray in the near-field region are evaluated based on time-averaged X-ray analysis techniques. Controlling parameters in the spray structure include swirl ratio, liquid phase Reynolds number, and gas phase Reynolds number. Data from the broadband X-ray radiographs obtained using a tube source at Iowa State University and from focused beam measurements at the Advanced Photon Source at Argonne National Laboratory are compared. The X-ray tube source at ISU was operated at two different energy levels, which reveals that the X-ray tube source energy influenced the magnitude of the optical depth but did not change the shape of the distribution. For the no swirl condition, gas flow rate and liquid flow rate had opposite effects on the spray profile, where the spray widens as the gas flow rate increases and narrows as the liquid flow rate increases. As the swirl ratio increases from 0 to 1, the spray widens and then narrows, which indicates that the effect of swirl being more dramatic

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“…Additionally, lead shielding was placed around the imaging equipment to shield it from scattered X-rays. Note that a significant change in this work from previous studies [8,10,15,16] is the increased field of view and frame rate provided by the Photron SA-Z camera and the different magnifications provided by the lens pairings.…”

Section: Figure 1: (A) Schematic Of the Airblast Nozzle Used In This mentioning

confidence: 95%

“…Adding swirl at this gas Reynolds number ( Figure 6) shortens the crown and leads to the formation of ligaments, wisps, and droplets much closer to the nozzle exit. Swirl also promotes an unstable gas core that periodically penetrates the liquid needle and causes sporadic dewetting [16]. Another feature found close to the nozzle are liquid droplets and some of the droplets enclose air bubbles.…”

Section: Figure 4: Image Sequence Right At the Nozzle Exit Taken At 3mentioning

confidence: 99%

High-Speed Flow Visualization of a Canonical Airblast Atomizer Using Synchrotron X-Rays

Heindel

Morgan

Burtnett

et al. 2019

Volume 4: Fluid Measurement and Instrumentation; Micro and Nano Fluid Dynamics

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Liquid sprays play a key role in many engineering processes and the dynamics at the nozzle exit have a significant impact on the downstream spray characteristics. However, visualizing the spray in this region is extremely challenging because, under most operating conditions, the spray is optically dense. High intensity white beam X-rays, like those found at the Advanced Photon Source (APS) at Argonne National Laboratory, can be used to produce time-resolved measurements of the liquid-gas structures in the spray near-field region. In this study, high temporal and spatial resolution X-ray images were acquired at the 7-BM beamline at APS of an atomization process using a canonical airblast atomizer consisting of coaxial liquid and gas jets. Unique flow structures were observed under various operating conditions, including bag, ligament, wisp, droplet, and air bubble formation, as well as hollowing of the liquid core into a crown at the liquid needle exit. Conditions where these structures exist are presented and their impact on spray formation are discussed.

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Synchrotron radiography characterization of the liquid core dynamics in a canonical two-fluid coaxial atomizer

Cited by 42 publications

References 17 publications

Feedback Control of Coaxial Atomization Based on the Spray Liquid Distribution

Feedback Control of Coaxial Atomization Based on the Spray Liquid Distribution

Time-Averaged Spray Analysis in the Near-Field Region Using Broadband and Narrowband X-Ray Measurements

High-Speed Flow Visualization of a Canonical Airblast Atomizer Using Synchrotron X-Rays

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