KTH ROYAL INSTITUTEOF TECHNOLOGY

Aerothermodynamics and exergy analysisin turbocharger radial turbineShyang Maw Lim, Anders Dahlkild, Mihai MihaescuKTH Mechanics, Competence Center for Gas Exchange (CCGEx)

CCGEx at the Royal Institute of Technology (KTH) • www.ccgex.kth.se

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https://www.carthrottle.com/post/the-difference-between-turbos-superchargers-explained/

The turbocharger turbine

Laurantzon F, Örlü R, Segalini A, Tillmark N, Alfredsson H. Experimental analysis of turbocharger interaction with a pulsatile flow through time-resolved flow measurements upstream and downstream of the turbine. In: Institution of MechanicalEngineers - 10th International Conference on Turbochargers and Turbocharging [Internet]. 2012. p. 405–15.

Lyttek P, Roclawski H, Böhle M, Gugau M. New Modular Test Rig for Unsteady Performance Assessment of Automotive Turbocharger Turbines. ASME. Turbo Expo: Power for Land, Sea, and Air, Volume 8: Microturbines, Turbochargers and Small Turbomachines; Steam Turbines ():V008T26A017. doi:10.1115/GT2017-64218.

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Trend in heat transfer research

∆" = $ − &1st law of thermodynamics

Aerothermodynamic losses?

Romagnoli, A. Manivannan, S. Rajoo, M.S. Chiong, A. Feneley, A. Pesiridis, R.F. Martinez-Botas, “A review of heat transfer in turbochargers,” Renew. Sustain. Energy Rev., vol. 79, no. Supplement C, pp. 1442–1460, 2017

Lim, S.M., Dahlkild, A. and Mihaescu, M. (2016) Wall treatment effects on the heat transfer in a radial turbine turbocharger. A. Segalini (ed.), Proceedings of the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015), Springer Proceedings in Physics 185, pp. 439-447, dx.doi.org/10.1007/978-3-319-30602-5_55

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q Limited insights into the thermo-fluid effects due to heat transfer with the first law of thermodynamic based method

qCustomary set-up ignore the presence of the upstream exhaust manifold

qLimited knowledge about the thermo-fluid physics under on-engine conditions

Research gaps & goal

Goal: Understand the thermo-fluid physics and the turbine performance under realistic engine conditions

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R1: What are the associated aerothermodynamic losses due to heat transfer?

R2: How can we quantify the losses?

R3. What are the effects of upstream exhaust manifold on the heat transfer and performance of the turbine?Today’s topic

Research questions & strategy

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Challenges & strategy

experiment measurement/visualization

Challenges Strategy

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Computational model

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nengine=1500 rpm

12

34

Inlet mass flow rate Rotational speed

Outlet pressure

Inlet total temperature

BCs: Full model

Detached Eddy Simulation(DES)

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Thermal BCs

Component Wall thermal conditionsExhaust manifold & scroll Tw= 1173 KRotor AdiabaticDiffuser & outlet duct Tw= 929 K

*Tw is the estimated average solid-fluid wall temperature from 1D model

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BCs: Simple model

Uniform distribution

1

2

3

4

2 1 3 4

2 1 3 4

Turbine inlet Turbine inlet

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Full model

Simple model

Section B-B

B

B

A

ASection A-A

180o

0o

270o 90o

270o 90o

0o

180o

Section B-B

B

B

A

ASection A-A

180o

0o

270o 90o

270o 90o

0o

180o

2 1 3 4

Flow field (1500 rpm)Turbine inlet (Section A-A)

2

1

3

4

Mid horizontal plane

at turbine inlet2 1 3 4

"̇

"̇ at turbine inlet

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Shaft work Exergy lost via heat transfer

Inflow exergy

Outflow exergy

Total irreversibilities

!"

1 −T&T'

Q̇*Ẇ,

System boundary

at temperature Tb

ENVIRONMENT(To, so, ho)

-̇./01 -̇./234

./ = ℎ7(97) − ℎ; − 9; ) −

CCGEx at the Royal Institute of Technology (KTH) • www.ccgex.kth.se

− "#∗ %

&'( ) − )* + , -.

=--0

12∗(%)

&'( -5 −--0

12∗(%)

6 -5

+ "#∗ %

9⃗×;⃗

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Flow exergy budget (1500 rpm)

Full

Sim

ple

q Scroll is most affected

q Turbine power is relatively unaffected

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Conclusions

qWhat are the effects of upstream exhaust manifold on the heat transfer rate and performance of the turbine?

Ø Fundamental thermo-fluid physics (i.e. secondary flow) in the scroll is governed by exhaust manifold

Ø Heat transfer rate & aerothermodynamic losses increaseØ Turbine power is relatively unaffected

Ø Take away: Model without exhaust manifold is sufficient for turbine power evaluation, but including the exhaust manifold if you would like to understand the overall physics

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Future challenges

High fidelity CFD

Improve 1D model for engine system optimization

Improve turbine design under pulsatile flow condition

Improve pulsatile flow test rig design for turbine research

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”Charging for the future”

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