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Publications (6 of 6) Show all publications
Lim, S. M., Dahlkild, A. & Mihaescu, M. (2019). Influence of Upstream Exhaust Manifold on Pulsatile Turbocharger Turbine Performance. Paper presented at 141(6), 061010. Journal of engineering for gas turbines and power, 141(6)
Open this publication in new window or tab >>Influence of Upstream Exhaust Manifold on Pulsatile Turbocharger Turbine Performance
2019 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 141, no 6Article in journal (Refereed) Published
Abstract [en]

This research was primary motivated by limited efforts to understand the effects of secondary flow and flow unsteadiness on the heat transfer and the performance of a turbocharger turbine subjected to pulsatile flow. In this study, we aimed to investigate the influence of exhaust manifold on the flow physics and the performance of its downstream components, including the effects on heat transfer, under engine-like pulsatile flow conditions. Based on the predicted results by detached eddy simulation (DES), qualitative and quantitative flow fields analyses in the scroll and the rotor's inlet were performed, in addition to the quantification of turbine performance by using the flow exergy methodology. With the specified geometry configuration and exhaust valve strategy, our study showed that (1) the exhaust manifold influences the flow field and the heat transfer in the scroll significantly and (2) although the exhaust gas blow-down disturbs the relative flow angle at rotor inlet, the consequence on the turbine power is relatively small.

Keywords
turbocharger turbine, engine-like pulsatile flow, heat transfer, exergy, DES
National Category
Mechanical Engineering Fluid Mechanics and Acoustics Vehicle Engineering
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-244665 (URN)10.1115/1.4042301 (DOI)000468915800011 ()2-s2.0-85061841259 (Scopus ID)
Conference
141(6), 061010
Funder
Swedish Energy Agency, 33834-3
Note

QC 20190226

Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2019-10-24Bibliographically approved
Lim, S. M. (2018). Aerothermodynamics and exergy analysis in turbocharger radial turbine. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Aerothermodynamics and exergy analysis in turbocharger radial turbine
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Coupling of turbomachine to reciprocating automotive engine in turbocharging leads to complex fluid flow and thermal characteristics in the turbine. Some undesirable characteristics include heat transfer, flow pulsation and secondary flow due to the complex geometry of the upstream exhaust manifold. The performed literature review exposed that there is a need for an enhanced understanding of the thermo-fluid physics of a turbocharger turbine operating under realistic on-engine conditions, and on quantifying the impact on the performance. Often, simplified set-ups and geometries are employed, neglecting the heat transfer.

This dissertation aimed to improve the quality of heat transfer analysis in a turbocharger turbine, and to enhance the understanding of aerothermodynamic effects due to heat transfer on the performance under engine-like pulsatile flow scenarios. Firstly, a flow exergy based analysis was developed to be used with the input provided by three-dimensional flow field data predicted by Detached Eddy Simulation (DES). Its applicability to identify and to quantify the aerothermodynamic related losses due to heat transfer was thoroughly investigated with a set-up replicating a hot gas stand continuous flow scenario. Next, the developed methodology was applied to engine-like pulsatile flow scenarios, to investigate the effects of flow pulsation and the influences of upstream exhaust manifold on the heat transfer and turbine performance. For the investigated geometry and specified boundary conditions, this dissertation mainly concluded that 1) The most sensitive measures associated with heat loss are the flow exergy lost via heat transfer and the thermal irreversibilities. The influence of heat loss on turbine power reduction is small in a relative sense, and 2) Although the exhaust manifold characteristics govern the fundamental flow physics and heat transfer in the scroll, its impact on the turbine power seems to be small relatively. 

The contributions with this dissertation were mainly twofold. Firstly, it contributes to a deeper understanding of the thermo-fluid physics of a turbocharger turbine operating under engine-like pulsating flow scenario. This knowledge might be useful for industrial product development in the future. Secondly, from academic perspective, the flow exergy budget analysis could potentially serve as a practical example to students in connecting the dots between classroom theory and real life engineering application.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 89
Series
TRITA-SCI-FOU ; 2018:41
Keywords
pulsatile exhaust flow, turbine, turbocharger, Detached Eddy Simulation, heat transfer, exergy
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-238833 (URN)978-91-7729-956-1 (ISBN)
Public defence
2018-12-07, Kollegiesalen, Brinellvägen 8, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

QC 20181113

Available from: 2018-11-13 Created: 2018-11-12 Last updated: 2018-11-13Bibliographically approved
Lim, S. M., Dahlkild, A. & Mihaescu, M. (2018). Aerothermodynamics and exergy analysis of a turbocharger radial turbine integrated with exhaust manifold. In: Institution of Mechanical Engineers - 13th International Conference on Turbochargers and Turbocharging 2018: . Paper presented at 13th International Conference on Turbochargers and Turbocharging, Twickenham Stadium, London 16 May 2018 - 17 May 2018.
Open this publication in new window or tab >>Aerothermodynamics and exergy analysis of a turbocharger radial turbine integrated with exhaust manifold
2018 (English)In: Institution of Mechanical Engineers - 13th International Conference on Turbochargers and Turbocharging 2018, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Large temperature gradients are associated with automotive turbocharger and thus the turbine experiences significant heat loss. Currently, the investigation of aerothermodynamic effects as a result of heat loss in turbine is commonly done by looking at the global performance parameters, i.e. pressure ratio and efficiency. This study aims to investigate the aerothermodynamic effects of heat transfer on a radial turbine operating under engine-like pulsating flow condition by identifying and quantifying the loss mechanisms via an exergy-based method using Detached Eddy Simulation data. Major findings with this study are: 1) Although exergy lost via heat transfer and internal irreversibilities could be as much as the turbine power, the drop of turbine power is only 4% as compared to an adiabatic turbine;2) Only about 12% of the available exhaust energy is extracted by the investigated turbine.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-238831 (URN)2-s2.0-85064985710 (Scopus ID)
Conference
13th International Conference on Turbochargers and Turbocharging, Twickenham Stadium, London 16 May 2018 - 17 May 2018
Note

QC 20181113

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2019-10-28Bibliographically approved
Lim, S. M., Dahlkild, A. & Mihaescu, M. (2018). Influence of upstream geometry on pulsatile turbocharger turbine performance. Shyang Maw Lim
Open this publication in new window or tab >>Influence of upstream geometry on pulsatile turbocharger turbine performance
2018 (English)Report (Other academic)
Abstract [en]

This research was primary motivated by limited efforts to understand the effects of secondary flow and flow unsteadiness on the heat transfer and the performance of a turbocharger turbine subjected to pulsatile flow. In this study, we aimed to investigate the influence of exhaust manifold on the flow physics and the performance of its downstream components, including the effects on heat transfer, under engine-like pulsatile flow conditions. Based on the predicted results by Detached Eddy Simulation (DES), qualitative and quantitative flow fields analyses in the scroll and the rotor’s inlet were performed, in addition to the quantification of turbine performance by using the flow exergy methodology. With the specified geometry configuration and exhaust valve strategy, our study showed that 1) The exhaust manifold influences the flow field and the heat transfer in the scroll significantly, and 2) Although the relative inflow angle at the rotor’s inlet is significantly affected by the initial exhaust gas blow down from the exhaust manifold, the consequence on the turbine power is relatively small.

Place, publisher, year, edition, pages
Shyang Maw Lim, 2018
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-238852 (URN)
Note

QC 20181113

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-14Bibliographically approved
Lim, S. M., Dahlkild, A. & Mihaescu, M. (2018). Influence of upstream geometry on pulsatile turbocharger turbine performance. In: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines: . Paper presented at ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018; Oslo; Norway; 11 June 2018 through 15 June 2018. ASME Press, 8
Open this publication in new window or tab >>Influence of upstream geometry on pulsatile turbocharger turbine performance
2018 (English)In: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines, ASME Press, 2018, Vol. 8Conference paper, Published paper (Refereed)
Abstract [en]

Unlike conventional turbomachinery, an automotive turbocharger's turbine is operated under unsteady hot and pulsatile flow due to the inherent nature of reciprocating engine. Although the turbine is integrated with exhaust manifold in real application, some experiments and numerical studies ignore its presence. In this study, we aimed to investigate the effects of upstream complex exhaust manifold on the prediction of pulse flow turbine performance via Detached Eddy Simulation (DES). Heat transfer was incorporated and the exergy based approach was used to quantify the heat transfer associated losses. Our primary results showed that under the investigated turbine stage, although the presence of exhaust manifold influences the prediction of heat transfer and internal irreversibilities in the scroll significantly, it does not significantly affect the prediction of turbine power, heat transfer and irreversibilities at the downstream components.

Place, publisher, year, edition, pages
ASME Press, 2018
Series
Proceedings of the ASME Turbo Expo ; 8
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-238345 (URN)10.1115/GT201876706 (DOI)2-s2.0-85053896779 (Scopus ID)9780791851173 (ISBN)
Conference
ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018; Oslo; Norway; 11 June 2018 through 15 June 2018
Note

QC 20181119

Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2018-11-19Bibliographically approved
Lim, S. M., Dahlkild, A. & Mihaescu, M. (2016). Wall Treatment Effects on the Heat Transfer in a Radial Turbine Turbocharger. In: Springer Proceedings in Physics: . Paper presented at 5th International Conference on Jets, Wakes and Separated Flows, ICJWSF2015, 15 June 2015 through 18 June 2015 (pp. 439-447). Springer Science+Business Media B.V.
Open this publication in new window or tab >>Wall Treatment Effects on the Heat Transfer in a Radial Turbine Turbocharger
2016 (English)In: Springer Proceedings in Physics, Springer Science+Business Media B.V., 2016, p. 439-447Conference paper, Published paper (Refereed)
Abstract [en]

Contradicting results about heat transfer effects on the performance of turbine turbocharger motivated this study. It was aimed to assess the effects that the wall treatment in a numerical sense has on the performance of a radial turbine of automotive turbocharger operating under a continuous flow condition. Adiabatic and non-adiabatic conditions were analyzed by using Unsteady Reynolds Averaged Navier-Stokes (URANS), Large Eddy Simulations (LES) and Detached Eddy Simulations (DES) approaches. When considering heat transfer, heat transfer loss at various locations is highly dependent on the near-wall modelling approach employed. Development of thermal boundary layer in the upstream region of turbine affects how the gas is convected in the downstream components, such as the scroll and the rotor. As long as the deviation in predicting thermal boundary layer does not affect the prediction of gas temperature at the inlet and outlet of the rotor, the difference in turbine power prediction by different near-wall modelling approaches was found to be small.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2016
Keywords
Boundary layers, Compressors, Forecasting, Large eddy simulation, Navier Stokes equations, Superchargers, Turbine components, Turbines, Turbomachinery, Wakes, Automotive turbochargers, Detached eddy simulations, Downstream components, Heat transfer effects, Heat transfer loss, Non-adiabatic conditions, Thermal boundary layer, Unsteady reynolds-averaged navier-stokes, Heat transfer
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-195489 (URN)10.1007/978-3-319-30602-5_55 (DOI)000387431400055 ()2-s2.0-84978943601 (Scopus ID)9783319306001 (ISBN)
Conference
5th International Conference on Jets, Wakes and Separated Flows, ICJWSF2015, 15 June 2015 through 18 June 2015
Note

QC 20161125

Available from: 2016-11-25 Created: 2016-11-03 Last updated: 2018-11-12Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6090-1498

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