Mixed flow turbines (MFTs) offer potential benefits for turbocharged engines when considering off-design performance and engine transient behavior. Although the performance and use of MFTs are described in the literature, little is published on the combined impact of the cone angle and the inlet blade angle, which are the defining features of such turbines. Numerical simulations were completed using a computational fluid dynamics (CFD) model that was validated against experimental measurements for a baseline geometry. The mechanical impact of the design changes was also analyzed. Based on the results of the numerical study, two rotors of different blade angle and cone angle were selected and manufactured. These rotors were tested using the Queen's University Belfast (QUB) low-temperature turbine test rig, which allowed for accurate and wide-range mapping of the turbine performance to low values of the velocity ratio. The performance results from these additional rotors were used to further validate the numerical findings. The numerical model was used to understand the underlying physical reasons for the measured performance differences through detailed consideration of the flow field at the rotor inlet and to document how the loss mechanisms and secondary flow structures developed with varying rotor inlet geometry. It was observed that large inlet blade cone angles resulted in strong separation and flow blockage near the hub at off-design conditions, which greatly reduced efficiency. However, the significant rotor inertia benefits achieved with the large blade cone angles were shown to compensate for the efficiency penalties and could be expected to deliver improved transient performance in downsized automotive engine applications.

References

References
1.
Minegishi
,
H.
,
Matsushita
,
H.
,
Sakakida
,
M.
, and
Koike
,
T
.,
1995
, “
Development of a Small Mixed-Flow Turbine for Automotive Turbochargers
”,
Proceedings of International Gas Turbine and Aeroengine Congress and Exposition, Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery
,
Houston, TX, USA
,
June 5–8, 1995
, Paper No. 95-GT-53.
2.
Baines
,
N. C.
,
Wallace
,
F. J.
, and
Whitfield
,
A.
,
1979
, “
Computer Aided Design of Mixed Flow Turbines for Turbochargers
,”
Trans. ASME
,
101
, pp.
440
449
.
3.
Abidat
,
M.
,
Chen
,
H.
, and
Baines
,
N. C.
,
1992
, “
Design of a Highly Loaded Mixed Flow Turbine
,”
Proc. Inst. Mech. Eng.
,
206
, pp.
95
107
.
4.
Arcoumanis
,
C.
,
Hakeem
,
I.
,
Khezzar
,
L.
, and
Martinez-Botas
,
R. F.
1995
. “
Performance of a Mixed Flow Turbocharger Turbine Under Pulsating Flow Conditions
,”
ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition
,
Houston, TX, USA
,
June 5–8
, ASME Paper No. 95-GT-210.
5.
Karamanis
,
N.
, and
Martinez-Botas
,
R. F.
,
2002
, “
Mixed Flow Turbines for Automotive Turbochargers: Steady and Unsteady Performance
,”
Int. J. Engine Res.
,
3
(
3
), pp.
127
138
.
6.
Rajoo
,
S.
, and
Martinez-Botas
,
R
.,
2008
, “
Mixed Flow Turbine Research: A Review
,”
ASME J. Turbomach.
,
130
(
4
),
044001
.
7.
Wang
,
J.
,
Michelini
,
J.
,
Wang
,
Y.
, and
Shelby
,
M.
,
2017
, “
Time to Torque Optimization by Evolutionary Computation Methods
,”
SAE Technical Paper No. 2017-01-1629
.
8.
Roclawski
,
H.
,
Böhle
,
M.
, and
Gugau
,
M.
,
2012
, “
Multidisciplinary Design Optimization of a Mixed Flow Turbine Wheel
,”
ASME Turbo Expo 2012: Turbine Technical Conference and Exposition
,
Copenhagen, Denmark
,
June 11–15
, ASME Paper No. GT2012-68233.
9.
Görke
,
M.
,
HagelStein
,
D.
,
Künstner
,
M.
,
Theobald
,
J.
,
Protiva
,
M.
,
Morand
,
N.
,
Jeckel
,
D.
, and
House
,
V.
,
2017
, “
The New 1.5l TSIevo Gasoline Engine From Volkswagen – Miller Cycle and Turbocharging With Variable Turbine Geometry
,”
The 22nd Supercharging Conference
,
Dresden, Germany
.
10.
Rajoo
,
S.
, and
Martinez-Botas
,
R.
,
2008
, “
Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study
,”
Int. J. Fluid Mach. Syst.
,
1
(
1
), pp.
155
168
.
11.
Walkingshaw
,
J.
,
Spence
,
S.
,
Filsinger
,
D.
, and
Thornhill
,
D.
,
2014
, “
A Numerical and Experimental Assessment of the Use of a Turbine Utilizing Splitter Blades for an Automotive Variable Geometry Turbocharger
,”
ASME Turbo Expo 2014: Turbine Technical Conference and Exposition
,
Düsseldorf, Germany
,
June 16–20
, ASME Paper No. GT2014-26097.
12.
Lüddecke
,
B.
,
Filsinger
,
D.
,
Ehrhard
,
J.
,
Steinacher
,
B.
,
Seene
,
C.
,
Bargende
,
M
.,
2013
, “
Contactless Shaft Torque Detection for Wide Range Performance Measurement of Exhaust Gas Turbocharger Turbines
,”
ASME J. Turbomach.
,
136
(
6
),
061022
.
13.
Walkingshaw
,
J.
,
Spence
,
S.
,
Ehrhard
,
J.
, and
Thornhill
,
D.
,
2014
, “
An Experimental Assessment of the Effects of Stator Vane Tip Clearance and Back Swept Blading on an Automotive Variable Geometry Turbocharger
,”
ASME J. Turbomach.
,
136
(
6
),
061001
.
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