A detailed study of the air flow through the fan stage of a high-bypass, geared turbofan in windmilling conditions is proposed, to address the key performance issues of this severe case of off-design operation. Experiments are conducted in the turbofan test rig of ISAE, specifically suited to reproduce windmilling operation in an ambient ground setup. The engine is equipped with conventional measurements and radial profiles of flow quantities are measured using directional five-hole probes to characterize the flow across the fan stage and derive windmilling performance parameters. These results bring experimental evidence of the findings of the literature that both the fan rotor and stator operate under severe off-design angle-of-attack, leading to flow separation and stagnation pressure loss. The fan rotor operates in a mixed fashion: spanwise, the inner sections of the rotor blades add work to the flow while the outer sections extract work and generate a pressure loss. The overall work is negative, revealing the resistive loads on the fan, caused by the bearing friction and work exchange in the different components of the fan shaft. The parametric study shows that the fan rotational speed is proportional to the mass flow rate, but the fan rotor inlet and outlet relative flow angles, as well as the fan load profile, remain constant, for different values of mass flow rate. Estimations of engine bypass ratio have been done, yielding values higher than six times the design value. The comprehensive database that was built will allow the validation of 3D Reynolds-averaged Navier–Stokes (RANS) simulations to provide a better understanding of the internal losses in windmilling conditions.

References

References
1.
Walsh
,
P. P.
, and
Fletcher
,
P.
,
2004
,
Gas Turbine Performance
,
Blackwell Science
, Oxford, UK.
2.
Anderson
,
B. A.
,
Messih
,
D.
, and
Plybon
,
R.
,
1997
, “
Engine Out Performance Characterisitics
,” 13th International Symposium on Air Breathing Engines (ISABE), 13th, Chattanooga, TN, Sept. 7–12, Paper No. 97-7216.
3.
Braig
,
W.
,
Schulte
,
H.
, and
Riegler
,
C.
,
1999
, “
Comparative Analysis of the Windmilling Performance of Turbojet and Turbofan Engines
,”
J. Propul. Power
,
15
(
2
), pp.
326
333
.10.2514/2.5430
4.
Riegler
,
C.
,
Bauer
,
M.
, and
Schulte
,
H.
,
2003
, “
Validation of a Mixed Flow Turbofan Performance Model in the Sub-Idle Operating Range
,”
ASME
Paper No. GT2003-38223.10.1115/GT2003-38223
5.
Pilet
,
J.
,
Lecordix
,
J.-L.
,
Garcia Rosa
,
N.
,
Barènes
,
R.
, and
Lavergne
,
G.
,
2011
, “
Towards a Fully Coupled Component Zomming Approach in Engine Performance Simulation
,”
ASME
Paper No. GT2011-46320. 10.1115/GT2011-46320
6.
Fuksman
,
I.
, and
Sirica
,
S.
,
2012
, “
Real-Time Execution of a High Fidelity Aero-Thermodynamic Turbofan Engine Simulation
,”
ASME J. Eng. Gas Turbines Power
,
134
(
5
), p.
054501
.10.1115/1.4004856
7.
Wallner
,
E. E.
, and
Welna
,
H. J.
,
1951
, “
Generalization of Turbojet and Turbine-Propeller Engine Performance in Windmilling Condition
,” National Advisory Committee for Aeronautics, Washington, DC, Technical Report No. NACA-RM-E51J23.
8.
Mishra
,
R. K.
,
Gouda
,
G.
, and
Vedaprakash
,
B. S.
,
2008
, “
Relight Envelope of a Military Gas Turbine Engine: An Experimental Study
,”
ASME
Paper No. 2008-43116. 10.1115/2008-43116
9.
Riegler
,
C.
,
Bauer
,
M.
, and
Kurzke
,
J.
,
2001
, “
Some Aspects of Modeling Compressor Behavior in Gas Turbine Performance Calculations
,”
ASME J. Turbomach.
,
123
(
2
), pp. 372–378.10.1115/1.1368123
10.
Zachos
,
P. K.
,
Grech
,
N.
,
Charnley
,
B.
,
Pachidis
,
V.
, and
Singh
,
R.
,
2011
, “
Experimental and Numerical Investigation of a Compressor Cascade at Highly Negative Incidence
,”
Eng. Appl. Comput. Fluid Mech.
,
5
(
1
), pp.
26
36
.
11.
Celestina
,
M. L.
,
Suder
,
K. L.
, and
Kulkarni
,
S.
,
2010
, “
Results of an Advanced Fan Stage Over a Wide Operating Range of Speed and Bypass Ratio: Part II—Comparison of CFD and Experimental Results
,”
ASME
Paper No. GT2010-44021.10.1115/GT2010-44021
12.
Prasad
,
D.
, and
Lord
,
W. K.
,
2010
, “
Internal Losses and Flow Behavior of a Turbofan Stage at Windmill
,”
ASME J. Turbomach.
,
132
(
3
), p.
031007
.10.1115/1.3147106
13.
SAE
2004
, “
Aircraft Propulsion System Performance Station Designation and Nomenclature
,”
SAE, Warrendale, PA, SAE Aerospace Standard
SAE-AS755 rev. D.
14.
Dufour
,
G.
,
Carbonneau
,
X.
, and
García Rosa
,
N.
,
2013
, “
Nonlinear Harmonic Simulations of the Unsteady Aerodynamics of a Fan Stage Section at Windmill
,”
ASME
Paper No. GT2013-95485.10.1115/GT2013-95485
You do not currently have access to this content.