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Study of in-cylinder ow structures using PIV and LES
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. (Laszlo Fuchs)ORCID iD: 0000-0003-1511-2235
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.ORCID iD: 0000-0001-9976-8316
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In-cylinder ow structures have a large eect on combustion eciency and emissions. Thus, understanding these structures is of great importance in the work of reducing fuel consumption and emissions. In this paper, the in-cylinder flow is studied using stereoscopic Particle Image Velocimetry (PIV) measurements and Large Eddy Simulations (LES). The measurements and simulations have been carried out on a steady swirl test rig, commonly used to measureengine characteristics such as the swirl number. In this study, the cause of the fluctuation in swirl is explained, showing that the fluctuation can be of greater importance as compared to the mean value of the swirl number. Moreover, we show how the flow from the inlet ports are distributed.

Keyword [en]
CFD, Engine, LES, PIV
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-124234OAI: oai:DiVA.org:kth-124234DiVA: diva2:633838
Funder
Swedish Energy Agency
Note

QS 2013

Available from: 2013-06-27 Created: 2013-06-27 Last updated: 2013-07-04Bibliographically approved
In thesis
1. Numerical Investigation of Internal Combustion Engine Related Flows
Open this publication in new window or tab >>Numerical Investigation of Internal Combustion Engine Related Flows
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Internal combustion engines has been used for more than 100 years. The use of the abundant energy supply stored as hydrocarbon fueled unprecedented economic growth. The use of hydrocarbons increased the work output of human labor significantly, thus increasing the economy and prosperity. However, during the latter part of the twentieth century negative consequences of the internal combustion engine has been noticed. Initially the being emissions of local pollutants such as carbon monoxide, nitrogen oxides and unburnt hydrocarbons. These pollutants have to this day in the western world been reduced significantly and further reductions are under way. Thereafter, has the focus been shifted somewhat to global emissions such as carbon dioxide due to the effect on the climate. However, as the most accessible oil resources have been exhausted the price of oil has five folded since the turn of the century, straining the exponential economic growth enjoyed for two centuries.

Heavy duty diesel engine efficiency is still below 50\%, there is thus a need and a possibility to further increase engine efficiency. In this thesis, work has been done to increase the understanding of the flow prior to combustion. A better knowledge of pre-combustion in-cylinder flow would increase the possibility to reduce engine emissions and fuel consumption, through better mixing and lower heat transfer.

The work presented is ordered in such a way that the flow structures created during the intake is presented first. Thereafter, the effect of compression is investigated. Intake flow structures are studied using Large-Eddy Simulations (LES) and experiments on a steady swirl test rig. The effects of compression are studied using simulations of predefined flow structures undergoing compression.

It is found that the flow structures created during intake is qualitatively different depending of intake valve lift. And that a single Swirl Number (SN) is an insufficient quantity to characterize the flow created at low valve lifts, due to high fluctuations. During compression it is found that a high swirl number suppress small scale turbulence while the compression has an increasing effect of axial fluctuations due to vorticity-dilation interaction. Additionally, it is shown that turbulent kinetic energy is introduced in the flow field by the piston in the absence of tumble breakdown.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. viii, 68 p.
Series
Trita-MEK, ISSN 0348-467X ; 2013:15
Keyword
CFD, LES, Engine, Intake, Compression
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-124237 (URN)978-91-7501-824-9 (ISBN)
Presentation
2013-08-20, E2, Lindstedsvagen 3, Kungliga Tekniska Högskolan, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency
Note

QC 20130704

Available from: 2013-07-04 Created: 2013-06-27 Last updated: 2013-07-04Bibliographically approved

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Söder, MartinPrahl Wittberg, Lisa

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