In most designs of two-spool turbofan engines, intermediate turbine ducts (ITDs) are used to connect the high-pressure turbine (HPT) with the low-pressure turbine (LPT). Demands for more efficient engines with reduced emissions require more “aggressive ducts,” ducts which provide both a higher radial offset and a larger area ratio in the shortest possible length, while maintaining low pressure losses and avoiding nonuniformities in the outlet flow that might affect the performance of the downstream LPT. The work presented in this paper is part of a more comprehensive experimental and computational study of the flowfield and the heat transfer in an aggressive ITD. The main objectives of the study were to obtain an understanding of the mechanisms governing the heat transfer in ITDs and to obtain high quality experimental data for the improvement of the CFD-based design tools. This paper presents and discusses the results of the experimental study. The duct studied was a state-of-the-art “aggressive” design with nine thick nonturning structural struts. It was tested in a large-scale low-speed experimental facility with a single-stage HPT. In this paper measurements of the steady convective heat transfer coefficient (HTC) distribution on both endwalls and on the strut for the duct design inlet conditions are presented. The heat transfer measurement technique used is based on infrared thermography. Part of the results of the flow measurements is also included.

References

References
1.
Dominy
,
R. G.
,
Kirkham
,
D. A.
, and
Smith
,
A. D.
, 1996, “
Flow Development Through Inter-Turbine Diffusers
,” ASME Paper No. 96-GT-139.
2.
Miller
,
R. J.
,
Moss
,
R. W.
,
Ainsworth
,
R. W.
, and
Harvey
,
N. W.
, 2004, “
The Effect of an Upstream Turbine on a Low-Aspect Ratio Vane
,” ASME Paper No. GT2004-54017.
3.
Göttlich
,
E.
,
Marn
,
A.
,
Malzacher
,
F. J.
,
Schennach
,
O.
, and
Heitmeir
,
F.
, 2007, “
Experimental Investigation of the Flow Through an Aggressive Intermediate Turbine Duct Downstream of a Transonic Turbine Stage
,”
Proceedings of the 7th European Turbomachinery Conference
.
4.
Marn
,
A.
,
Göttlich
,
E.
,
Pecnik
,
R.
,
Malzacher
,
F. J.
,
Schennach
,
O.
, and
Pirker
,
H. P.
, 2007, “
The Influence of Blade Tip Gap Variation on the Flow Through an Aggressive S-shaped Intermediate Turbine Duct Downstream a Transonic Turbine Stage—Part I: Time-averaged Results
,” ASME Paper No. GT2007-27405.
5.
Göttlich
,
E.
,
Marn
,
A.
,
Pecnik
,
R.
,
Malzacher
,
F. J.
,
Schennach
,
O.
, and
Pirker
H. P.
, 2007, “
The Influence of Blade Tip Gap Variation on the Flow Through an Aggressive S-shaped Intermediate Turbine Duct Downstream a Transonic Turbine Stage—Part II: Time-resolved Results and Surface Flow
,” ASME Paper No. GT2007-28069.
6.
Marn
,
A.
,
Göttlich
,
E.
,
Cadrecha
,
D.
, and
Pirker
,
H. P.
, 2008, “
Shorten the Intermediate Turbine Duct Length by Applying an Integrated Concept
,” ASME Paper No. GT2008-50269.
7.
Marn
,
A.
, 2008, “
On the Aerodynamics of Intermediate Turbine Ducts for Competitive and Environmentally Friendly Jet Engines
”, Ph.D. thesis, Technical University Of Graz, Graz, Austria.
8.
Axelsson
,
L.-U.
, and
Johansson
,
T. G.
, 2008, “
Experimental Investigation of the Time-Averaged Flow in an Intermediate Turbine Duct
,” ASME Paper No. GT2008-50829.
9.
Axelsson
,
L.-U.
, and
George
,
W. K.
, 2008, “
Spectral Analysis of the Flow in an Intermediate Turbine Duct
,” ASME Paper No. GT2008-51340.
10.
Axelsson
,
L.-U.
, and
Johansson
,
T. G.
, 2008, “
Evaluation of the Flow in an Intermediate Turbine Duct at Off-Design Conditions
,” ICAS Paper No. ICAS 2008-4.6.2.
11.
Axelsson
,
L.-U.
, 2009, “
Experimental Investigation of the Flow Field in an Aggressive Intermediate Turbine Duct
,” Ph.D. thesis, Chalmers University of Technology, Gothenburg, Sweden.
12.
Arroyo Osso
,
C.
,
Wallin
,
F.
, and
Johansson
,
T. G.
, 2008, “
Experimental and Numerical Investigation of an Aggressive Intermediate Turbine Duct: Part 2—Flowfield Under Off-Design Inlet Conditions
,” AIAA Paper No. AIAA-2008-7056.
13.
Arroyo
,
C.
, 2009, “
Aerothermal Investigation of an Intermediate Turbine Duct
,” Ph.D. Thesis, Chalmers University of Technology, Gothenburg, Sweden.
14.
Arroyo Osso
,
C.
,
Axelsson
L.-U.
,
Håll
,
U.
,
Johansson
,
T. G.
,
Larsson
,
J.
, and
Haselbach
,
F.
, 2006, “
Large-Scale Low-Speed Facility for Investigating Intermediate Turbine Duct Flows
,” AIAA Paper No. AIAA-2006-1312.
15.
Wallin
,
F.
,
Eriksson
,
L.-E.
, and
Nilsson
,
M.
, 2006, “
Intermediate Turbine Duct Design and Optimization
,” ICAS Paper No. ICAS 2006-5.1.1.
16.
Lohrengel
,
J.
, and
Todtenhaupt
,
R.
, 1996, “
Thermal Conductivity, Degree of Total Emissivity and Spectral Emissivity of the Nextel Velvet Coating
,”
PTB-Mitteilungen
,
106
, pp.
259
265
.
17.
Incropera
,
F. P.
, and
DeWitt
,
D. P.
, 2002,
Fundamentals of Heat and Mass Transfer
,
5th ed.
,
John Wiley
,
New York
.
You do not currently have access to this content.