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Effect of Swirl/Tumble (Tilt) Angle on Flow Homogeneity, Turbulence and Mixing Properties
KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0001-9976-8316
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Mechanics of Industrial Processes. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
2014 (English)In: SAE 2014 International Powertrains, Fuels and Lubricants Meeting, FFL 2014, Vol. 2014-OctoberArticle in journal (Refereed) Published
Abstract [en]

In this work, the effect of swirl to tumble ratio on homogeneity, turbulence and mixing in a generic heavy duty Diesel engine during compression, is investigated using Large-Eddy Simulations. The main conclusion is that the relative importance of dilatation (relative volume change) increases whereas the effect of tumble breakdown decreases with the swirl to tumble ratio. In detail, we show that an increase in tumble raises the peak turbulence level and shifts the peak to earlier crank angles, which in turn leads to higher dissipation. Moreover, maximum turbulence level at top dead center is obtained for a combination of swirl and tumble rather than for pure tumble. Furthermore, it is observed that the peak turbulent kinetic energy displays levels three times greater than the initial kinetic energy of the tumble motion. Thus, energy is added to the flow (turbulence) by the piston through generation of vorticity by vorticity-dilatation interaction. Also, the intermediate swirl/tumble ratios are found to introduce large non-uniformity in the flow field, leading to a non-solid body like rotation. Swirl/tumble (tilt) angles larger than 19°are necessary for complete mixing of the gas within the engine cylinder. Taken together, the combined effect of a combination of swirl and tumble turbulence during compression is investigated. This knowledge is important both for engine development as well as more theoretical aspects regarding the breakdown of large scale structures in an engine.

Place, publisher, year, edition, pages
SAE International , 2014. Vol. 2014-October
Keyword [en]
Computational fluid dynamics, Diesel engines, Engine cylinders, Engines, Kinetic energy, Kinetics, Large eddy simulation, Mixing, Powertrains, Solid lubricants, Turbomachinery, Vorticity, Effect of swirls, Engine development, Heavy-duty diesel engine, Large scale structures, Non-uniformities, Theoretical aspects, Turbulence level, Turbulent kinetic energy, Turbulence
National Category
Mechanical Engineering
URN: urn:nbn:se:kth:diva-176217DOI: 10.4271/2014-01-2579ScopusID: 2-s2.0-84938545225OAI: diva2:873106
SAE 2014 International Powertrain, Fuels & Lubricants Meeting, 20 October 2014 - 22 October 2014

QC 20151123

Available from: 2015-11-23 Created: 2015-11-02 Last updated: 2015-11-23Bibliographically approved

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