The performance of automotive turbocharger turbines has long been realized to be quite different under pulsating flow conditions compared to that under the equivalent steady and quasi-steady conditions on which the conventional design concept is based. However, the mechanisms of this phenomenon are still intensively investigated nowadays. This paper presents an investigation of the response of a stand-alone rotor to inlet pulsating flow conditions by using a validated unsteady Reynolds-averaged Navier–Stokes solver (URANS). The effects of the frequency, the amplitude, and the temporal gradient of pulse waves on the instantaneous and cycle integrated performance of a radial turbine rotor in isolation were studied, decoupled from the upstream turbine volute. A numerical method was used to help gain the physical understanding of these effects. A validation of the numerical method against the experiments on a full configuration of the turbine was performed prior to the numerical tool being used in the investigation. The rotor was then taken out to be studied in isolation. The results show that the turbine rotor alone can be treated as a quasi-steady device only in terms of cycle integrated performance; however, instantaneously, the rotor behaves unsteadily, which increasingly deviates from the quasi-steady performance as the local reduced frequency of the pulsating wave is increased. This deviation is dominated by the effect of quasi-steady time lag; at higher local reduced frequency, the transient effects also become significant. Based on this study, an interpretation and a model of estimating the quasi-steady time lag have been proposed; a criterion for unsteadiness based on the temporal local reduced frequency concept is developed, which reduces to the Λ criterion proposed in the published literature when cycle averaged. This in turn emphasizes the importance of the pressure wave gradient in time.

References

References
1.
Palfreyman
,
D.
, and
Martinez-Botas
,
R. F.
,
2005
, “
The Pulsating Flow Field in a Mixed Flow Turbocharger Turbine: An Experimental and Computational Study
,”
ASME J. Turbomach.
,
127
(
1
), pp. 144–155.10.1115/1.1812322
2.
Wallace
,
F.
, and
Blair
,
G.
,
1965
, “
The Pulsating Flow Performance of Inward Radial Flow Turbines
,”
ASME
Paper No. 65-GTP-21.
3.
Benson
,
R.
, and
Scrimshaw
,
K.
,
1965
, “
An Experimental Investigation of Non-Steady Flow in a Radial Gas Turbine
,”
Proc. I. Mech. E.
,
180
(10), pp. 74–85.10.1243/PIME_CONF_1965_180_283_02
4.
Kosuge
,
H.
,
Yamanaka
,
N.
,
Ariga
,
I.
, and
Watanabe
,
I.
,
1976
, “
Performance of Radial Flow Turbines Under Pulsating Flow Conditions
,”
ASME J. Eng. Power
,
98
(
1
), pp.
53
59
.10.1115/1.3446110
5.
Capobianco
,
M.
,
Gambarotta
,
A.
, and
Cipolla
,
G.
,
1989
, “
Influence of the Pulsating Flow Operation on the Turbine Characteristics of a Small Internal Combustion Engine Turbocharger
,”
Proc. of IMechE
, Paper No. C372/019.
6.
Capobianco
,
M.
, and
Gambarotta
,
A.
,
1990
, “
Unsteady Flow Performance of Turbocharger Radial Turbines
,”
Proc. of IMechE
, Paper No. C405/017.
7.
Dale
,
A.
, and
Watson
,
N.
,
1986
, “
Vaneless Radial Turbocharger Turbine Performance
,”
IMechE Turbocharging and Turbochargers
, Paper No. C110/86.
8.
Yeo
,
J.
, and
Baines
,
N.
,
1990
, “
Pulsating Flow Behavior in a Twin-Entry Vaneless Radial Inflow Turbine
,”
IMechE Turbocharging and Turbochargers
, Paper C405/004, pp
113
122
.
9.
Winterbone
,
D.
,
Nikpour
,
B.
, and
Alexander
,
G.
,
1990
, “
Measurement of the Performance of a Radial Inflow Turbine in Conditional Steady and Unsteady Flow
,”
Proceedings of the 4th International Conference on Turbocharging and Turbochargers
, London, May 22–24.
10.
Abidat
,
M.
,
Hachemi
,
M.
,
Hamidou
,
M.
, and
Baines
,
N.
,
1998
, “
Prediction of the Steady and Non-Steady Flow Performance of a Highly Loaded Mixed Flow Turbine
,”
IMechE A J. Power Energy
,
212
(
3
), pp.
173
184
.10.1243/0957650981536844
11.
Karamanis
,
N.
,
Martinez-Botas
,
R. F.
, and
Su
,
C. C.
,
2001
, “
Mixed Flow Turbines: Inlet and Exit Flow Under Steady and Pulsating Conditions
,”
ASME J. Turbomach.
,
123
(
2
), pp. 359–371.10.1115/1.1354141
12.
Szymko
,
S.
,
Martinez-Botas
,
R. F.
, and
Pullen
,
K. R.
,
2005
, “
Experimental Evaluation of Turbocharger Turbine Performance Under Pulsating Flow Conditions
,”
ASME
Paper No. GT2005-68878.10.1115/GT2005-68878
13.
Rajoo
,
S.
, and
Martinez-Botas
,
R. F.
,
2010
, “
Unsteady Effect in a Nozzled Turbocharger Turbine
,”
ASME J. Turbomach.
,
132
(3), p. 031001.10.1115/1.3142862
14.
Copeland
,
C.
,
Martinez-Botas
,
R.
, and
Seiler
,
M.
,
2012
, “
Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions
,”
ASME J. Turbomach.
,
134
(2), p. 021022.10.1115/1.4003171
15.
Baines
,
N.
,
Hajilouy-Benisi
,
A.
, and
Yeo
,
J.
,
1994
, “The Pulse Flow Performance and Modelling of Radial Inflow Turbines,” IMechE International Conference on Turbocharging and Turbochargers, London, June 7–9, Paper No. C484/006/94, pp. 209–220.
16.
Chen
,
H.
,
Hakeem
,
I.
, and
Martinez-Botas
R.F.
,
1996
, “
Modelling of a Turbocharger Turbine Under Pulsating Inlet Conditions
,”
IMechE A J. Power Energy
,
210
(
51
), pp.
397
408
.10.1243/PIME_PROC_1996_210_063_02
17.
Costall
,
A.
,
Szymko
,
S.
,
Martinez-Botas
,
R. F.
,
Filsinger
,
D.
, and
Ninkovic
D.
,
2006
, “
Assessment of Unsteady Behavior in Turbocharger Turbines
,”
ASME
Paper No. GT2006-90348.10.1115/GT2006-90348
18.
Lam
,
J.
,
Roberts
,
Q.
, and
McDonnell
,
G.
,
2002
, “
Flow Modelling of a Turbocharger Turbine Under Pulsating Flow
,”
7th International Conference on Turbochargers and Turbocharging
, London, May 14–15, pp. 181–196.
19.
Padzillah
,
M. H.
,
Rajoo
,
S.
, and
Martinez-Botas
,
R. F.
,
2012
, “
Numerical Assessment of Unsteady Flow Effects on a Nozzled Turbocharger Turbine
,”
ASME
Paper No. GT2012-69062.10.1115/GT2012-69062
20.
Hellstrom
,
F.
, and
Fuchs
,
L.
,
2009
, “
Numerical Computational of the Pulsatile Flow in a Turbocharger With Realistic Inflow Conditions From an Exhaust Manifold
,”
ASME
Paper No. GT2009-59619.10.1115/GT2009-59619
21.
Chen
,
H.
, and
Winterbone
,
D.
,
1990
, “
A Method to Predict Performance of Vaneless Radial Turbines Under Steady and Unsteady Flow Conditions
,”
IMechE Turbocharging and Turbochargers
, Paper No. C405/008, pp
13
22
.
22.
Benson
,
R.
,
1974
, “
Nonsteady Flow in a Turbocharger Nozzleless Radial Gas Turbine
,”
SAE
Technical Paper 740739.10.4271/740739
23.
Baines
,
N. C.
,
2010
, “
Turbocharger Turbine Pulse Flow Performance and Modelling 25 Years On
,”
IMechE 9th International Conference on Turbochargers and Turbocharging
, London, May 19–20, Paper No. C1302/028.
24.
Winterbone
,
D.
,
Nikpour
,
B.
, and
Frost
,
H.
,
1991
, “
A Contribution to the Understanding of Turbocharger Turbine Performance in Pulsating Flow
,”
Proc. Inst. Mech. Eng., Part C: Mech. Eng. Sci.
, Paper No. C433/011. pp.
19
28
.
25.
Copeland
,
C.
,
Newton
,
P.
,
Martinez-Botas
,
R. F.
, and
Seiler
,
M.
,
2012
, “
A Comparison of Timescales Within a Pulsed Flow Turbocharger Turbine
,”
IMechE 10th International Turbochargers and Turbocharging
, London, May 15–16.
26.
Costall
,
A.
, and
Martinez-Botas
,
R. F.
,
2007
, “
Fundamental Characterization of Turbocharger Turbine Unsteady Flow Behavior
,”
ASME
Paper No. GT2007–28317.10.1115/GT2007-28317
27.
Denton
,
J. D.
,
1992
, “
The Calculations of Three Dimensional Viscous Flow Through Multistage Turbomachines
,”
ASME J. Turbomach.
,
144
, pp.
18
26
.10.1115/1.2927983
28.
Denton
,
J. D.
,
2002
, “
The Effects of Lean and Sweep on Transonic Fan Performance: A Computational Study
,”
Task Quarterly
,
6
(
1
), pp.
7
23
.
You do not currently have access to this content.