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Disintegration Mechanisms of Intermittent Liquid Jets
KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0002-7729-3484
KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0001-6242-4739
KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0001-9976-8316
KTH, School of Engineering Sciences (SCI), Mechanics.
2016 (English)In: SAE International Journal of Fuels and Lubricants, ISSN 1946-3952, E-ISSN 1946-3960, Vol. 9, no 1, 91-99 p.Article in journal (Refereed) Published
Abstract [en]

It has been observed that intermittent injection leads to improved spray characteristics in terms of mixing and gas entrainment. Although some experimental work has been carried out in the past, the disintegration mechanisms that govern the breakup of intermittent jets remain unknown. In this paper we have carried out a systematic numerical analysis of the breakup of pulsated jets under different injection conditions. More specifically, the duty cycle (share of active injection during one cycle) is varied, while the total cycle time is kept constant. The advection of the liquid phase is handled through the Volume of Fluid approach and, in order to provide an accurate, yet computationally acceptable, resolution of the turbulent structures, the implicit Large Eddy Simulation has been adopted. The results show that the primary disintegration results from a combination of stretching, collision and aerodynamic interaction effects. Moreover, there exists a strong coupling between stretching and collision as stretching makes the pulse thinner prior to the contact between pulses. In this work, the purpose is to study the collision contribution to breakup in terms of the near nozzle pulse disintegration rate. When approaching the low duty cycle limit, this effect is significant because of the lower liquid volume of the pulse. In contrast, for a high duty cycle, the stretching effect is limited and a wide tail region remains as an obstruction for following pulses. However, the integral momentum of the pulse is maintained to a larger degree that has an adverse effect on the outcome of the collision event.

Place, publisher, year, edition, pages
SAE International , 2016. Vol. 9, no 1, 91-99 p.
Keyword [en]
Liquids, Aerodynamic interactions, Disintegration rate, Implicit large Eddy simulations, Injection conditions, Intermittent injection, Spray characteristics, Stretching effect, Turbulent structures
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-195060DOI: 10.4271/2016-01-0851ScopusID: 2-s2.0-84983488600OAI: oai:DiVA.org:kth-195060DiVA: diva2:1043965
Note

QC 20161101

Available from: 2016-11-01 Created: 2016-11-01 Last updated: 2016-11-01Bibliographically approved

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Nygård, AlexanderAltimira, MireiaPrahl Wittberg, LisaFuchs, Laszlo
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