To manage the increasing turbine temperatures of future gas turbines a cooled cooling air system has been proposed. In such a system some of the compressor efflux is diverted for additional cooling in a heat exchanger (HX) located in the bypass duct. The cooled air must then be returned, across the main gas path, to the engine core for use in component cooling. One option is do this within the combustor module and two methods are examined in the current paper; via simple transfer pipes within the dump region or via radial struts in the prediffuser. This paper presents an experimental investigation to examine the aerodynamic impact these have on the combustion system external aerodynamics. This included the use of a fully annular, isothermal test facility incorporating a bespoke 1.5 stage axial compressor, engine representative outlet guide vanes (OGVs), prediffuser, and combustor geometry. Area traverses of a miniature five-hole probe were conducted at various locations within the combustion system providing information on both flow uniformity and total pressure loss. The results show that, compared to a datum configuration, the addition of transfer pipes had minimal aerodynamic impact in terms of flow structure, distribution, and total pressure loss. However, the inclusion of prediffuser struts had a notable impact increasing the prediffuser loss by a third and consequently the overall system loss by an unacceptable 40%. Inclusion of a hybrid prediffuser with the cooled cooling air (CCA) bleed located on the prediffuser outer wall enabled an increase of the prediffuser area ratio with the result that the system loss could be returned to that of the datum level.

References

References
1.
Advisory Council Aviation Research and Innovation in Europe
,
2011
,
Flightpath 2050—Europe's Vision for Aviation
, Publications Office of the European Union, Luxembourg.
2.
Wilfert
,
G.
,
Sieber
,
J.
,
Rolt
,
A.
,
Baker
,
N.
,
Touyeras
,
A.
, and
Colantuoni
,
S.
,
2007
, “
New Environmental Friendly Aero Engine Core Concepts
,”
ISABE Paper No. 2007-1120
.http://www.newac.eu/uploads/media/No.03_NEWAC_Isabe_07.pdf
3.
A'Barrow
,
C. R.
,
Carrotte
,
J. F.
,
Walker
,
A. D.
, and
Rolt
,
A.
,
2013
, “
Aerodynamic Performance of a Coolant Flow Off-Take Downstream of an OGV
,”
ASME J. Turbomach.
,
135
(
1
), p. 011006.
4.
Fishenden
,
C. R.
, and
Stevens
,
S. J.
,
1977
, “
Performance of Annular Combustor-Dump Diffusers
,”
J. Aircr.
,
14
(
1
), pp.
60
67
.
5.
Bailey
,
D.
,
Carrotte
,
J. F.
, and
Frodsham
,
C. W.
,
1995
, “
Detailed Measurements on a Modern Combustor Dump Diffuser System
,”
ASME J. Eng. Gas Turbines Power
,
117
(
4
), pp.
678
685
.
6.
Walker
,
A. D.
,
Carrotte
,
J. F.
, and
Denman
,
P. A.
,
2011
, “
Annular Diffusers With Large Downstream Blockage Effects for Gas Turbine Combustion Applications
,”
AIAA J. Propul. Power
,
27
(
6
), pp.
1218
1230
.
7.
Walker
,
A. D.
,
Carrotte
,
J. F.
, and
McGuirk
,
J. J.
,
2008
, “
Compressor/Diffuser/Combustor Aerodynamic Interactions in Lean Module Combustors
,”
ASME J. Eng. Gas Turbines Power
,
130
(
1
), p.
011504
.
8.
Walker
,
A. D.
,
Carrotte
,
J. F.
, and
McGuirk
,
J. J.
,
2009
, “
The Influence of Dump Gap on External Combustor Aerodynamics at High Fuel Injector Flow Rates
,”
ASME J. Eng. Gas Turbines Power
,
131
(
3
), p.
031506
.
9.
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 Aerodynamic Lifting Struts
,”
ASME
Paper No. GT2014-25844.
10.
Barker
,
A. G.
, and
Carrotte
,
J. F.
,
2002
, “
Compressor Exit Conditions and Their Impact on Flame Tube Injector Flows
,”
ASME J. Eng. Gas Turbines Power
,
124
(
1
), pp.
10
19
.
11.
Stevens
,
S. J.
,
Nayak
,
U. S. L.
,
Preston
,
J. F.
,
Robinson
,
P. J.
, and
Scrivener
,
C. T. J.
,
1978
, “
Influence of Compressor Exit Conditions on Diffuser Performance
,”
J. Aircr.
,
15
(
8
), pp.
482
488
.
12.
Stevens
,
S. J.
, and
Williams
,
G. J.
,
1980
, “
The Influence of Inlet Conditions on the Performance of Two Annular Diffusers
,”
ASME J. Fluids Eng.
,
102
(
3
), pp.
357
363
.
13.
Stevens
,
S. J.
,
Harasgama
,
S. P.
, and
Wray
,
A. P.
,
1984
, “
The Influence of Blade Wakes on Combustor Shortened Pre-Diffusers
,”
J. Aircr.
,
21
(
9
), pp.
641
648
.
14.
Zierer
,
T.
,
1993
, “
Experimental Investigation of the Flow in Diffusers Behind an Axial Flow Compressor
,”
ASME
Paper No. 93-GT-347.
15.
Barker
,
A. G.
, and
Carrotte
,
J. F.
,
2001
, “
The Influence of Compressor Exit Conditions on Combustor Annular Diffusers—Part I: Diffuser Performance
,”
AIAA J. Propul. Power
,
17
(
3
), pp.
678
686
.
16.
Barker
,
A. G.
, and
Carrotte
,
J. F.
,
2001
, “
The Influence of Compressor Exit Conditions on Combustor Annular Diffusers—Part II: Flow Redistribution Within the Diffuser
,”
AIAA J. Propul. Power
,
17
(
3
), pp.
687
694
.
17.
Cumpsty
,
N. A.
,
1989
,
Compressor Aerodynamics
,
Longman Scientific and Technical
,
Harlow, Essex, UK
.
18.
Wray
,
A. P.
, and
Carrotte
,
J. F.
,
1993
, “
The Development of a Large Annular Facility for Testing Gas Turbine Combustor Diffuser Systems
,”
AIAA
Paper No. 93-2546.
19.
Klein
,
A.
,
1995
, “
Characteristics of Combustor Diffusers
,”
Prog. Aerosp. Sci.
,
31
(
3
), pp.
171
271
.
20.
Howard
,
J. H. G.
,
Henseler
,
H. J.
, and
Thornton-Trump
,
A. B.
,
1967
, “
Performance and Flow Regimes for Annular Diffusers
,”
ASME
Paper No. 67-WA/FE-21.
21.
Walker
,
A. D.
,
Denman
,
P. A.
, and
McGuirk
,
J. J.
,
2004
, “
Experimental and Computational Study of Hybrid Diffusers for Gas Turbine Combustors
,”
ASME J. Eng. Gas Turbines Power
,
126
(
4
), pp.
717
725
.
22.
Walker
,
A. D.
, and
Denman
,
P. A.
,
2005
, “
Hybrid Diffusers for Radially Staged Combustion Systems
,”
AIAA J. Propul. Power
,
21
(
2
), pp.
264
273
.
23.
Ford
,
C. L.
,
Carrotte
,
J. F.
, and
Walker
,
A. D.
,
2012
, “
The Impact of Compressor Exit Conditions on Fuel Injector Flows
,”
ASME J. Eng. Gas Turbines Power
,
134
(
11
), p.
111504
.
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