Grouping and trapping of evaporating droplets in an oscillating gas flow

D. Katoshevski; T. Shakked; Sergei Sazhin; Cyril Crua; Morgan Heikal

doi:10.1016/j.ijheatfluidflow.2007.10.003

Grouping and trapping of evaporating droplets in an oscillating gas flow

D. Katoshevski, T. Shakked, Sergei Sazhin, Cyril Crua, Morgan Heikal

University of Brighton

Research output: Contribution to journal › Article › peer-review

Abstract

A new approach to the analysis of droplet grouping in an oscillating gas flow is suggested. This is based on the investigation of droplet trajectories in the frame of reference moving with the phase velocity of the wave. Although the equations involved are relatively simple, the analysis shows distinctive characteristics of grouping and non-grouping cases. In the case of grouping, droplet trajectories converge to the points for which the ratio of flow velocity in this frame of reference and the amplitude of flow oscillations is less than 1, and the cosine of this ratio is positive. In the case of non-grouping, droplet trajectories in this frame of reference oscillate around the translational velocity close to the velocity of flow in the same frame of reference. The effect of the droplet size on the grouping pattern is investigated. It has been pointed out that for the smaller droplets much more stable grouping is observed. The effect of droplet evaporation is studied in the limiting case when the contribution of the heat-up period can be ignored. It is shown that evaporation can lead to droplet grouping even in the case when the non-evaporating droplets are not grouped. This is related to the reduction in droplets diameter during the evaporation process. Coupling between gas and droplets is shown to decrease the grouping tendency. A qualitative agreement between predictions of the model and in-house experimental observations referring to Diesel engine sprays has been demonstrated.

Original language	English
Pages (from-to)	415-426
Number of pages	12
Journal	International Journal of Heat and Fluid Flow
Volume	29
Issue number	2
DOIs	https://doi.org/10.1016/j.ijheatfluidflow.2007.10.003
Publication status	Published - 1 Apr 2008

Bibliographical note

This is the author’s version of a work that was accepted for publication in International Journal of Heat and Fluid Flow. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Heat and Fluid Flow, 29, 2, 2008 10.1016/j.ijheatfluidflow.2007.10.003

Keywords

spray
grouping
trapping
evaporation
coupled solution

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Cite this

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title = "Grouping and trapping of evaporating droplets in an oscillating gas flow",

abstract = "A new approach to the analysis of droplet grouping in an oscillating gas flow is suggested. This is based on the investigation of droplet trajectories in the frame of reference moving with the phase velocity of the wave. Although the equations involved are relatively simple, the analysis shows distinctive characteristics of grouping and non-grouping cases. In the case of grouping, droplet trajectories converge to the points for which the ratio of flow velocity in this frame of reference and the amplitude of flow oscillations is less than 1, and the cosine of this ratio is positive. In the case of non-grouping, droplet trajectories in this frame of reference oscillate around the translational velocity close to the velocity of flow in the same frame of reference. The effect of the droplet size on the grouping pattern is investigated. It has been pointed out that for the smaller droplets much more stable grouping is observed. The effect of droplet evaporation is studied in the limiting case when the contribution of the heat-up period can be ignored. It is shown that evaporation can lead to droplet grouping even in the case when the non-evaporating droplets are not grouped. This is related to the reduction in droplets diameter during the evaporation process. Coupling between gas and droplets is shown to decrease the grouping tendency. A qualitative agreement between predictions of the model and in-house experimental observations referring to Diesel engine sprays has been demonstrated.",

keywords = "spray, grouping, trapping, evaporation, coupled solution",

author = "D. Katoshevski and T. Shakked and Sergei Sazhin and Cyril Crua and Morgan Heikal",

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AU - Shakked, T.

AU - Sazhin, Sergei

AU - Crua, Cyril

AU - Heikal, Morgan

N1 - This is the author’s version of a work that was accepted for publication in International Journal of Heat and Fluid Flow. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Heat and Fluid Flow, 29, 2, 2008 10.1016/j.ijheatfluidflow.2007.10.003

PY - 2008/4/1

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N2 - A new approach to the analysis of droplet grouping in an oscillating gas flow is suggested. This is based on the investigation of droplet trajectories in the frame of reference moving with the phase velocity of the wave. Although the equations involved are relatively simple, the analysis shows distinctive characteristics of grouping and non-grouping cases. In the case of grouping, droplet trajectories converge to the points for which the ratio of flow velocity in this frame of reference and the amplitude of flow oscillations is less than 1, and the cosine of this ratio is positive. In the case of non-grouping, droplet trajectories in this frame of reference oscillate around the translational velocity close to the velocity of flow in the same frame of reference. The effect of the droplet size on the grouping pattern is investigated. It has been pointed out that for the smaller droplets much more stable grouping is observed. The effect of droplet evaporation is studied in the limiting case when the contribution of the heat-up period can be ignored. It is shown that evaporation can lead to droplet grouping even in the case when the non-evaporating droplets are not grouped. This is related to the reduction in droplets diameter during the evaporation process. Coupling between gas and droplets is shown to decrease the grouping tendency. A qualitative agreement between predictions of the model and in-house experimental observations referring to Diesel engine sprays has been demonstrated.

AB - A new approach to the analysis of droplet grouping in an oscillating gas flow is suggested. This is based on the investigation of droplet trajectories in the frame of reference moving with the phase velocity of the wave. Although the equations involved are relatively simple, the analysis shows distinctive characteristics of grouping and non-grouping cases. In the case of grouping, droplet trajectories converge to the points for which the ratio of flow velocity in this frame of reference and the amplitude of flow oscillations is less than 1, and the cosine of this ratio is positive. In the case of non-grouping, droplet trajectories in this frame of reference oscillate around the translational velocity close to the velocity of flow in the same frame of reference. The effect of the droplet size on the grouping pattern is investigated. It has been pointed out that for the smaller droplets much more stable grouping is observed. The effect of droplet evaporation is studied in the limiting case when the contribution of the heat-up period can be ignored. It is shown that evaporation can lead to droplet grouping even in the case when the non-evaporating droplets are not grouped. This is related to the reduction in droplets diameter during the evaporation process. Coupling between gas and droplets is shown to decrease the grouping tendency. A qualitative agreement between predictions of the model and in-house experimental observations referring to Diesel engine sprays has been demonstrated.

KW - spray

KW - grouping

KW - trapping

KW - evaporation

KW - coupled solution

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DO - 10.1016/j.ijheatfluidflow.2007.10.003

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SP - 415

EP - 426

JO - International Journal of Heat and Fluid Flow

JF - International Journal of Heat and Fluid Flow

IS - 2

ER -

Grouping and trapping of evaporating droplets in an oscillating gas flow

Abstract

Bibliographical note

Keywords

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