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Numerical investigations of a free turbulent jet after a 90° pipe bend
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.ORCID iD: 0000-0002-6603-0099
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.ORCID iD: 0000-0001-7330-6965
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this study the ow out of pipe after a 90pipe bend has been investigated byperforming Large Eddy Simulations. Comparisons of velocity proles, ow eldsand power spectral densities have been performed between numerical simulationsand experiments. Pipe bends exists in many industrial applications especiallyin the internal combustion engine. Performing accurate and predictive pipe owsimulations is becoming more important when more of the development work isbeing performed by simulations. The long term goal of this project is to helpwith development of simpler models that are faster to run but give the sameaccuracy. During this study it was found that the method used works well bothin predicting mean values and in resolving dynamic motions such as vortexswitching. LES calculations without a SGS model has been proven to work wellwith ows of this type as long as the grid resolution is suciently ne.

National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-123085OAI: oai:DiVA.org:kth-123085DiVA: diva2:624484
Note

QS 2013

Available from: 2013-05-31 Created: 2013-05-31 Last updated: 2013-06-03Bibliographically approved
In thesis
1. Unsteady simulations of the turbulent flow in the exhaust system of an IC-engine for optimal energy utilization
Open this publication in new window or tab >>Unsteady simulations of the turbulent flow in the exhaust system of an IC-engine for optimal energy utilization
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This licentiate thesis deals with the ow in pipe bends and radial turbines inan internal combustion engine environment. Looking into the engine bay of apassenger car one cannot avoid noticing all the pipe bends and splits. Duringthe development of internal combustion engines the engine manufacturers arestarting to focus more on simulations than on experiments. This is partly becauseof the reduction in cost but also the reduction in turn around time. This isone of the reasons for the need of more accurate and predictive simulations.By using more complex computational methods the accuracy and predictivecapabilities are increased. The downside is that the computational time isincreasing so the long term goal of the project is to use the results to improvethe predictive capability of the lower order methods used by the industry.By comparing experiments, Reynolds Averaged Navier-Stokes (RANS)simulations, and Large Eddy Simulations (LES), the accuracy of the simulationmethods can be established. The advantages of using LES over RANS for the ows under consideration stems from the unsteadiness of the ow in the enginemanifolds. When such unsteadiness overlaps the natural turbulent spectrum,general RANS models cannot handle the problem specic ow. The thesisconsiders this eect on the chosen numerical model. The LES results have beenshown to be more accurate than the RANS simulations both for global meanvalues and for the uctuating components. The LES calculations have provento predict the mean

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 116 p.
Series
Trita-MEK, ISSN 0348-467X ; 2013:11
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-123086 (URN)978-91-7501-782-2 (ISBN)
Presentation
2013-06-14, E3, Osquarsbacke 14, Stockholm, 13:15 (English)
Opponent
Supervisors
Note

QC 20130603

Available from: 2013-06-03 Created: 2013-05-31 Last updated: 2013-06-03Bibliographically approved

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Fjällman, JohanMihaescu, Mihai

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