Abstract

The need to reduce fuel-burn and emissions is pushing turbofan engines toward geared architectures with higher bypass ratios and small ultrahigh-pressure ratio cores. However, this increases the radial offset between compressor spools leading to a more challenging design for compressor transition ducts. For the duct connecting the fan to the engine core, this is further complicated by poor-quality flow generated at the fan hub, which is characterized by low total pressure and large rotating secondary flow structures. This paper presents an experimental evaluation of a new rotor designed to produce these larger flow structures and examines their effect on the performance of an engine sector stators (ESS) and compressor transition duct. Aerodynamic data were collected via five-hole probes, for time-averaged pressures and velocities and phase-locked hot-wire anemometry to capture the rotating secondary flows. The data showed that larger structures promoted mixing through the ESS increasing momentum exchange between the core and boundary layer flows. Measurements within the duct showed a continued reduction in the hub boundary layer, suggesting the duct had moved further from separation. Consequently, an aggressive duct with 12.5% length reduction was designed and tested and measurements confirmed the duct remained fully attached. Total pressure loss was slightly increased over the ESS, but this was offset by reduced loss in the duct due to improved flow quality. Overall, this length reduction represents a significant cumulative effect in reduced fuel-burn and emissions over the life of an engine.

References

1.
Walker
,
A. D.
,
Mariah
,
I.
,
Tsakmakidou
,
D.
,
Vadhvana
,
H.
, and
Hall
,
C.
,
2020
, “
The Influence of Fan Root Flow on the Aerodynamic of a Low-Pressure Compressor Transition Duct
,”
ASME. J. Turbomach.
,
142
(
1
), p.
011002
.10.1115/1.4045272
2.
Rolls-Royce Plc.
,
2017
, “
iFAN Fan-Intake Coupling at Cruise
,”
Rolls-Royce Plc
,
UK
,
Report No. RCR91535.
3.
Sieverding
,
C. H.
, and
Van Den Bosche
,
P.
,
1983
, “
The Use of Coloured Smoke to Visualize Secondary Flows in a Turbine-Blade Cascade
,”
J. Fluid Mech.
,
134
(
1
), pp.
85
89
.10.1017/S0022112083003237
4.
Langston
,
L. S.
,
2006
, “
Secondary Flows in Axial Turbines—A Review
,”
Ann. New York Acad. Sci.
,
934
(
1
), pp.
11
26
.10.1111/j.1749-6632.2001.tb05839.x
5.
Harvey
,
N. W.
,
2008
, “
Some Effects of Non-Axisymmetric End Wall Profiling on Axial Flow Compressor Aerodynamics: Part I—Linear Cascade Investigation
,”
ASME
Paper No. GT2008-50990.10.1115/GT2008-50990
6.
Germain
,
T.
,
Nagel
,
M.
, and
Baier
,
R.
,
2007
, “
Visualisation and Quantification of Secondary Flows: Application to Turbine Bladings With 3D-Endwalls
,”
Eighth International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows
, Lyon, France, July 2–6, Paper No. ISAIF8-0098.https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.469.8336&rep=rep1&type=pdf
7.
Denton
,
J. D.
,
1993
, “
Loss Mechanisms in Turbomachines
,”
ASME. J. Turbomach.
,
115
(
4
), pp.
621
630
.10.1115/1.2929299
8.
Kang
,
S.
, and
Hirsch
,
C.
,
1993
, “
Experimental Study on the Three- Dimensional Flow Within a Compressor Cascade With Tip Clearance: Part I—Velocity and Pressure Fields
,”
ASME. J. Turbomach.
,
115
(
3
), pp.
435
443
.10.1115/1.2929270
9.
Zamboni
,
G.
, and
Xu
,
L.
,
2012
, “
Fan Root Aerodynamics for Large Bypass Gas Turbine Engines: Influence on the Engine Performance and 3D Design
,”
ASME. J. Turbomach.
,
134
(
6
), p.
061017
.10.1115/1.4006286
10.
Walker
,
A. D.
,
Barker
,
A. G.
,
Mariah
,
I.
,
Peacock
,
G. L.
,
Carrotte
,
J. F.
, and
Northall
,
R. M.
,
2014
, “
An Aggressive S-Shaped Compressor Transition Duct With Swirling Flow and Aerodynamically Lifting Struts
,”
ASME
Paper No. GT2014-25844.10.1115/GT2014-25844
11.
Britchford
,
K. M.
,
Manners
,
A. P.
,
McGuirk
,
J. J.
, and
Stevens
,
S. J.
,
1994
, “
Measurements and Prediction of Flow in Annular S-Shaped Ducts
,”
Exp. Therm. Fluid Sci.
,
9
(
2
), pp.
197
205
.10.1016/0894-1777(94)90112-0
12.
Tsakmakidou
,
D.
,
Walker
,
A. D.
, and
Hall
,
C.
,
2020
, “
A Numerical Investigation Into Secondary Flows at the Inlet to a Low-Pressure Compressor Transition Duct
,”
ASME
Paper GT2020-16065.10.1115/GT2020-16065
13.
Cumpsty
,
N. A.
,
1989
, “
Compressor Aerodynamics
,”
Longman Scientific and Technical
,
J. Wiley
,
Harlow, Essex, UK
.
14.
Wray
,
A. P.
, and
Carrotte
,
J. F.
,
1993
, “
The Development of a Large Annular Facility for Testing Gas Turbine
,”
AIAA
Paper No. 1993-2546.10.2514/6.1993-2546
15.
Klein
,
A.
,
1981
, “
Review: Effects of Inlet Conditions on Conical-Diffuser Performance
,”
ASME. J. Fluids Eng.
,
103
(
2
), pp.
250
257
.10.1115/1.3241727
16.
Camp
,
T. R.
, and
Shin
,
H. W.
,
1995
, “
Turbulence Intensity and Length Scale Measurements in Multistage Compressors
,”
ASME. J. Turbomach.
,
117
(
1
), pp.
38
46
.10.1115/1.2835642
17.
Bruun
,
H.
,
1995
,
Hot Wire Anemometry
,
Oxford University Press
,
New York
.
18.
Dantec Dynamics
,
2021
, “
Dantec Dynamics
,” Dantec Dynamics, Skovlunde, Denmark, accessed Aug. 27, 2021, www.dantecdynamics.com
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