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Research Papers

Understanding the Twin Scroll Turbine: Flow Similarity

[+] Author and Article Information
Nils Brinkert

e-mail: nils.brinkert@daimler.com

Siegfried Sumser

e-mail: siegfried.sumser@daimler.com

Siegfried Weber

e-mail: siegfried.weber@daimler.com

Klaus Fieweger

e-mail: klaus.fieweger@daimler.com
Daimler AG, Mercedesstrasse 143/5 G254,
70546 Stuttgart, Germany

Achmed Schulz

e-mail: achmed.schulz@kit.edu

Hans-Jörg Bauer

Professor
e-mail: hans-joerg.bauer@kit.edu
Karlsruhe Institute of Technology,
Kaiserstr. 12 Geb. 1091,
76131 Karlsruhe, Germany

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 13, 2011; final manuscript received November 3, 2011; published online November 19, 2012. Editor: David Wisler.

J. Turbomach 135(2), 021039 (Nov 19, 2012) (10 pages) Paper No: TURBO-11-1204; doi: 10.1115/1.4006607 History: Received September 13, 2011; Revised November 03, 2011

The current study investigates the flow conditions of a twin scroll asymmetric turbine. This is motivated by the operating conditions of the turbine at a heavy-duty reciprocating internal combustion engine with exhaust gas recirculation. The flow conditions of the turbine at the engine can be described best with the turbine scroll interaction map. Standard hot gas measurements of a turbocharger turbine are presented and discussed. Due to the strong interaction of the turbine scrolls, further hot gas measurements are performed at partial admission conditions. The turbine inlet conditions are analyzed experimentally, in order to characterize the turbine performance. The turbine scroll pressure ratio is varied, leading to unequal twin turbine admission conditions. The flow behavior is analyzed regarding its ability for further extrapolation. Beyond scroll pressure ratio variations, unequal temperature admission conditions were studied. A way of characterizing the representative turbine inlet temperature, regarding the reduced turbine speed, is presented. The different scroll parameter ratios are evaluated regarding their capability of describing flow similarity under different unequal turbine admission conditions. In this content, turbine scroll Mach number ratio, velocity ratio and mass flow ratio are assessed. Furthermore, a generic representation of the turbine flow conditions at the engine is presented, based on standard turbine performance maps.

Copyright © 2013 by ASME
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References

Figures

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Fig. 1

Asymmetric twin scroll turbine operating mode

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Fig. 2

Flow possibilities for the twin scroll turbine [3]

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Fig. 3

Standard turbine performance measurements at a standard hot gas test bench

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Fig. 4

Small turbine scroll flow interaction map comparing hot gas test bench and engine measurements

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Fig. 5

Turbine efficiencies versus blade speed ratio during one engine cycle compared to hot gas tests

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Fig. 6

Schematic representation of the experimental facility used for the turbocharger test bench measurements

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Fig. 7

Turbocharger test bench of the twin scroll turbine

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Fig. 8

Mass flow parameter versus pressure ratio of the large turbine scroll under SPR variation

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Fig. 9

Mass flow parameter versus pressure ratio of the small turbine scroll under SPR variation

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Fig. 10

Turbine efficiency over the pressure ratio of the small turbine scroll under SPR variation

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Fig. 11

Constant scroll pressure ratio variation seen in the flow interaction map of the small turbine scroll

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Fig. 12

Mass flow parameter of the large turbine scroll at constant turbine scroll Mach number ratios

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Fig. 13

Mass flow parameter of the small turbine scroll at constant turbine scroll Mach number ratios

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Fig. 14

Turbine efficiency over the small turbine scroll pressure ratio at constant turbine scroll Mach number ratios

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Fig. 15

Constant scroll Mach number ratios seen in the flow interaction map of the small turbine scroll

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Fig. 16

Flow parameter at constant scroll temperature ratios at equal pressure admission conditions

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Fig. 17

Turbine efficiency at constant scroll temperature ratios at equal pressure admission conditions

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Fig. 18

Flow parameter of the large turbine scroll at different constant turbine scroll parameter ratios

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Fig. 19

Turbine efficiency over small scroll pressure ratio at different constant turbine scroll parameter ratios

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Fig. 20

Turbine flow interaction map of small scroll at different constant turbine scroll parameter ratios

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