The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

Accurate prediction of the discharge coefficient (C<sub>D</sub>) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the C<sub>D</sub> of IMTF atomizers are unavailable. This wo...

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Main Authors: Farid A. Hammad, Kai Sun, Jan Jedelsky, Tianyou Wang
Format: Article
Language:English
Published: MDPI AG 2020-05-01
Series:Processes
Subjects:
twin-fluid nozzles
internal-mixing methods
discharge coefficient
atomization
two-phase flow
Online Access:https://www.mdpi.com/2227-9717/8/5/563
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spelling doaj-cfa6ab5dd5334a699003b94b2efcb1a92020-11-25T02:01:35ZengMDPI AGProcesses2227-97172020-05-01856356310.3390/pr8050563The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid AtomizersFarid A. Hammad0Kai Sun1Jan Jedelsky2Tianyou Wang3State Key Laboratory of Engines, Tianjin University, Tianjin 300072, ChinaState Key Laboratory of Engines, Tianjin University, Tianjin 300072, ChinaFaculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 616 69 Brno, Czech RepublicState Key Laboratory of Engines, Tianjin University, Tianjin 300072, ChinaAccurate prediction of the discharge coefficient (C<sub>D</sub>) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the C<sub>D</sub> of IMTF atomizers are unavailable. This work presents an experimental study on C<sub>D</sub> for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (∆p<sub>mix</sub>/p<sub>amb</sub>), the orifice length-to-diameter ratio (L<sub>o</sub>/d<sub>o</sub>), and the liquid viscosity (µ<sub>L</sub>). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that C<sub>D</sub> is governed mainly by GLR, and reduces if GLR, L<sub>o</sub>/d<sub>o</sub>, or µ<sub>L</sub> is increased. An increase in ∆p<sub>mix</sub>/p<sub>amb</sub> causes a C<sub>D</sub> reduction up to ∆p<sub>mix</sub>/p<sub>amb</sub> = 0.98, and C<sub>D</sub> increases for a higher ∆p<sub>mix</sub>/p<sub>amb</sub>. Surprisingly, differences in C<sub>D</sub> amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general C<sub>D</sub> correlation fitting with an R<sup>2</sup> ≥0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.https://www.mdpi.com/2227-9717/8/5/563twin-fluid nozzlesinternal-mixing methodsdischarge coefficientatomizationtwo-phase flow
collection DOAJ
language English
format Article
sources DOAJ
author Farid A. Hammad
Kai Sun
Jan Jedelsky
Tianyou Wang
spellingShingle Farid A. Hammad
Kai Sun
Jan Jedelsky
Tianyou Wang
The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers
Processes
twin-fluid nozzles
internal-mixing methods
discharge coefficient
atomization
two-phase flow
author_facet Farid A. Hammad
Kai Sun
Jan Jedelsky
Tianyou Wang
author_sort Farid A. Hammad
title The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers
title_short The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers
title_full The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers
title_fullStr The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers
title_full_unstemmed The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers
title_sort effect of geometrical, operational, mixing methods, and rheological parameters on discharge coefficients of internal-mixing twin-fluid atomizers
publisher MDPI AG
series Processes
issn 2227-9717
publishDate 2020-05-01
description Accurate prediction of the discharge coefficient (C<sub>D</sub>) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the C<sub>D</sub> of IMTF atomizers are unavailable. This work presents an experimental study on C<sub>D</sub> for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (∆p<sub>mix</sub>/p<sub>amb</sub>), the orifice length-to-diameter ratio (L<sub>o</sub>/d<sub>o</sub>), and the liquid viscosity (µ<sub>L</sub>). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that C<sub>D</sub> is governed mainly by GLR, and reduces if GLR, L<sub>o</sub>/d<sub>o</sub>, or µ<sub>L</sub> is increased. An increase in ∆p<sub>mix</sub>/p<sub>amb</sub> causes a C<sub>D</sub> reduction up to ∆p<sub>mix</sub>/p<sub>amb</sub> = 0.98, and C<sub>D</sub> increases for a higher ∆p<sub>mix</sub>/p<sub>amb</sub>. Surprisingly, differences in C<sub>D</sub> amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general C<sub>D</sub> correlation fitting with an R<sup>2</sup> ≥0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.
topic twin-fluid nozzles
internal-mixing methods
discharge coefficient
atomization
two-phase flow
url https://www.mdpi.com/2227-9717/8/5/563
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