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Experimental investigation on the effect of pulsations on exhaust manifold-related flows aiming at improved efficiency
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).ORCID iD: 0000-0001-8127-8124
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).ORCID iD: 0000-0002-1663-3553
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).ORCID iD: 0000-0002-1146-3241
2012 (English)In: Institution of Mechanical Engineers - 10th International Conference on Turbochargers and Turbocharging, 2012, 377-387 p.Conference paper, Published paper (Refereed)
Abstract [en]

The gas flowing through the exhaust manifold of the internal combustion engine to the inlet of the turbine side of a turbocharger is highly pulsating and turbulent. The gas enters the turbine after travelling through a complex curved and branched pipe system where the effect of centrifugal (from the acute curvature), inertia and viscous forces result in a three-dimensional, non-symmetric flow field. Additionally, vortical structures are being formed and dissolved due to the co-existence of these forces that change in magnitude under a pulse period. This complex flow field, typical for the inflow condition to the turbine, is the focus of the present study. Instantaneous mass flow rate and pressure measurements that provide information on changes in the turbine map when a sharp bend is mounted at the inlet of the turbine are performed and complemented with time-resolved stereoscopic particle image velocimetry measurements of the pulsating turbulent flow downstream a 90° pipe bend. The results indicate, that the time-averaged operation point in a turbine map is only marginally affected by the inflow conditions and the pulsation frequency. The hysteresis loops, on the other hand, exhibit differences not only for different pulsation frequencies, but also for different inflow conditions as a comparison between a straight and a curved pipe section upstream the turbine shows.

Place, publisher, year, edition, pages
2012. 377-387 p.
Keyword [en]
Centrifugation, Exhaust manifolds, Flow fields, Internal combustion engines, Superchargers
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-83153Scopus ID: 2-s2.0-84865479030ISBN: 978-085709209-0 (print)OAI: oai:DiVA.org:kth-83153DiVA: diva2:498748
Conference
10th International Conference on Turbochargers and Turbocharging; London;15 May 2012 through 16 May 2012
Funder
StandUp
Note

QC 20120425

Available from: 2012-02-12 Created: 2012-02-12 Last updated: 2013-04-16Bibliographically approved
In thesis
1. Experimental study of turbulent flows through pipe bends
Open this publication in new window or tab >>Experimental study of turbulent flows through pipe bends
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with turbulent flows in 90 degree curved pipes of circular cross-section. The flow cases investigated experimentally are turbulent flow with and without an additional motion, swirling or pulsating, superposed on the primary flow. The aim is to investigate these complex flows in detail both in terms of statistical quantities as well as vortical structures that are apparent when curvature is present. Such a flow field can contain strong secondary flow in a plane normal to the main flow direction as well as reverse flow.

The motivation of the study has mainly been the presence of highly pulsating turbulent flow through complex geometries, including sharp bends, in the gas exchange system of Internal Combustion Engines (ICE). On the other hand, the industrial relevance and importance of the other type of flows were not underestimated.

The geometry used was curved pipes of different curvature ratios, mounted at the exit of straight pipe sections which constituted the inflow conditions. Two experimental set ups have been used. In the first one, fully developed turbulent flow with a well defined inflow condition was fed into the pipe bend. A swirling motion could be applied in order to study the interaction between the swirl and the secondary flow induced by the bend itself. In the second set up a highly pulsating flow (up to 40 Hz) was achieved by rotating a valve located at a short distance upstream from the measurement site. In this case engine-like conditions were examined, where the turbulent flow into the bend is non-developed and the pipe bend is sharp. In addition to flow measurements, the effect of non-ideal flow conditions on the performance of a turbocharger was investigated.

Three different experimental techniques were employed to study the flow field. Time-resolved stereoscopic particle image velocimetry was used in order to visualize but also quantify the secondary motions at different downstream stations from the pipe bend while combined hot-/cold-wire anemometry was used for statistical analysis. Laser Doppler velocimetry was mainly employed for validation of the aforementioned experimental methods.

The three-dimensional flow field depicting varying vortical patterns has been captured under turbulent steady, swirling and pulsating flow conditions, for parameter values for which experimental evidence has been missing in literature.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2012. viii, 85 p.
Series
Trita-MEK, ISSN 0348-467X ; 2012:05
Keyword
Turbulent flow, swirl, pulsation, pipe bend, hot-wire anemometry, cold-wire anemometry, laser Doppler velocimetry, stereoscopic particle image velocimetry.
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-93316 (URN)978-91-7501-321-3 (ISBN)
Presentation
2012-05-03, D3, Lindstedtsvägen 5, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20120425Available from: 2012-04-25 Created: 2012-04-13 Last updated: 2012-04-25Bibliographically approved

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Örlü, RamisAlfredsson, P. Henrik

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