Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Unsteady simulations of the turbulent flow in the exhaust system of an IC-engine for optimal energy utilization
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.ORCID iD: 0000-0002-6603-0099
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: urn:nbn:se:kth:diva-123086ISBN: 978-91-7501-782-2 (print)OAI: oai:DiVA.org:kth-123086DiVA: diva2:624491
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
List of papers
1. GT-Power Report
Open this publication in new window or tab >>GT-Power Report
2013 (English)Report (Other academic)
Abstract [en]

Presently in the vehicle industry full engine system simulations are performedusing dierent one-dimensional software programs in order to assess the eectof dierent geometrical and part changes on the system as a whole. Thesesimulations are usually fast and multiple parameters can be monitored andanalysed.In this report GT-Power simulations have been performed on a completeengine designed by Volvo Car Corporation. The investigation was performedin order to gain basic knowledge about the internal combustion engine andspecically about the gas exchange system and the turbocharger. A parameterstudy was performed and the responses on the turbine eciency and breaktorque were analysed.The trends in the simulation results follow the background theory well, i.e.increasing the turbine eciency increases the engine eciency and reduces thetime to torque. The eect of the valve opening times and durations on thebreak torque and the turbine eciency can be studied. There is an intricaterelationship where the optimal conguration is dependent on the engine speedas well as the opening angles and times.GT-Power is a very powerful tool for simulating complete engines. Howevercare must be taken when analysing the results. The code only uses one directionand time, meaning that the ow will always be uniform in the cross sections.Whereas in many parts of the real engine the ow eld is three dimensional andfar from uniform in the cross-sections.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-123083 (URN)
Note

QC 20130603

Available from: 2013-05-31 Created: 2013-05-31 Last updated: 2014-09-19Bibliographically approved
2. Effects of inlet geometry on turbine performance
Open this publication in new window or tab >>Effects of inlet geometry on turbine performance
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this study comparisons have been performed between gas-stand experiments,Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations, and LargeEddy Simulations (LES) of the ow through a radial turbine of a turbochargerdesigned for an internal combustion engine. The long term goal for the projectis to improve the prediction capabilities for the simpler computational modelsused by industry in the research and development of new products. At thepresent stage the eects of using simplied geometries and methods for turbineperformance predictions are assessed. Additionally, data obtained from URANScalculations is compared against experimental data and against unsteady LESresults. The comparisons are made in order to evaluate the employed methodologies,to know when to use simplied models with reasonable accuracy, as wellas to justify the use of more advanced methods when the models are inadequate.It was found out that the LES results are closer to the gas-stand experimentsthan the URANS predictions are.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-123084 (URN)
Note

QS 2013

Available from: 2013-05-31 Created: 2013-05-31 Last updated: 2014-09-19Bibliographically approved
3. Numerical investigations of a free turbulent jet after a 90° pipe bend
Open this publication in new window or tab >>Numerical investigations of a free turbulent jet after a 90° pipe bend
(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:nbn:se:kth:diva-123085 (URN)
Note

QS 2013

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

Open Access in DiVA

Unsteady simulations of the turbulent ow in the exhaust system of an IC-engine for optimal energy utilization(5523 kB)1928 downloads
File information
File name FULLTEXT01.pdfFile size 5523 kBChecksum SHA-512
56c244eb5423580a8a022dd59d0431fd083b5bc4a69d4e36cc41e3a964978c500eaf546fbd5a66bc5a09f059d5941338f6af91e83326b50b605ed22dda94419a
Type fulltextMimetype application/pdf

Authority records BETA

Fjällman, Johan

Search in DiVA

By author/editor
Fjällman, Johan
By organisation
Fluid Physics
Fluid Mechanics and Acoustics

Search outside of DiVA

GoogleGoogle Scholar
Total: 1928 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 240 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf