This paper investigates the effects of inlet disturbance caused by crosswind on a fan blade operation and addresses the possible aerodynamic instabilities, which can arise for such a fan-intake system. The work is carried out by using a three-dimensional unsteady computational fluid dynamics (CFD) model (AU3D), and for a modern low-speed fan rig for which extensive measured data is available. The computational domain includes the fan with outlet guide vanes for the bypass flow, engine-section stators for the core, and a symmetric intake upstream of the fan (a whole low-pressure domain). The unsteady full annulus simulations under crosswind are performed to analyze the effects of inlet disturbances on the operation of this blade. It was observed that, for sufficiently high amplitudes of crosswind, the intake lip separates, and results in a significant loss of stall margin. Moreover, even in the absence of lip separation, the blade can still stall prematurely due to nonhomogeneous flow caused by the two contra-rotating trailing vortices. In the second phase of this study, the effects of fan loading on the suppression of flow separation in the intake, and the consequent stall margin of the fan blade, were explored. The results indicated that, as the fan speed increases, it becomes more capable of reducing the inlet distortion levels, and consequently, the loss in stall margin decreases.

References

References
1.
Hughes
,
C.
,
2011
, “
Aircraft Engine Technology for Green Aviation to Reduce Fuel Burn
,”
AIAA
Paper No. 2011-3531.
2.
Peters
,
A.
,
Spakovszky
,
Z. S.
,
Lord
,
W. K.
, and
Rose
,
B.
,
2015
, “
Ultrashort Nacelles for Low Fan Pressure Ratio Propulsors
,”
ASME J. Turbomach.
,
137
(2), p.
201001
.
3.
Freeman
,
C.
, and
Rowe
,
A. L.
,
1999
, “
Intake Engine Interactions of a Modern Large Turbofan Engine
,”
ASME
Paper No. 99-GT-344.
4.
Nishioka
,
T.
,
Kanno
,
T.
, and
Hayami
,
H.
, “
Rotor-Tip Flow Fields Near Inception Point of Modal Disturbance in an Axial-Flow Fan
,”
ASME
Paper No. GT2010-22187.
5.
Mistry
,
C.
, and
Pradeep
,
A.
,
2014
, “
Experimental Investigation of a High Aspect Ratio, Low Speed Contra-Rotating Fan Stage With Complex Inflow Distortion
,”
Propul. Power Res.
,
3
(
2
), pp.
68
81
.
6.
Longley
,
J. P.
, and
Greitzer
,
E. M.
,
1992
, “
Inlet Distortion Effects in Aircraft Propulsion System Integration
,” Fundamentals and Special Problems of Synthetic Aperture Radar (SAR), AGARD Lecture Series, Advisory Group for Aerospace Research and Development, Cambridge University, Cambridge, MA, Report No.
92N28464
https://ntrs.nasa.gov/search.jsp?R=19920019221
7.
Murphy
,
J. P.
, and
MacManus
,
D. G.
,
2011
, “
Ground Vortex Aerodynamics Under Crosswind Conditions
,”
Exp. Fluids
,
50
(
1
), pp.
109
124
.
8.
Zantopp
,
S.
,
MacManus
,
D. G.
, and
Murphy
,
J. P.
,
2010
, “
Computational and Experimental Study of Intake Ground Vortices
,”
Aeronaut. J.
,
114
(
1162
), pp.
769
784
.
9.
Trapp
,
L. G.
, and
Motta Girardi
,
R.
,
2010
, “
Crosswind Effects on Engine Inlets: The Inlet Vortex
,”
J. Aircr.
,
47
(
2
), pp.
577
590
.
10.
Carnevale
,
M.
,
Wang
,
F.
,
Green
,
J. S.
, and
Di Mare
,
L.
,
2016
, “
Lip Stall Suppression in Powered Intakes
,”
J. Propul. Power
,
32
(
1
), pp.
161
170
.
11.
Cao
,
T.
,
Vadlamani
,
N. R.
,
Tucker
,
P. G.
,
Smith
,
A. R.
,
Slaby
,
M.
, and
Sheaf
,
C. T. J.
,
2016
, “
Fan-Intake Interaction Under High Incidence
,”
ASME
Paper No. GT2016-56561.
12.
Page
,
J. H.
,
Hield
,
P.
, and
Tucker
,
P. G.
,
2017
, “
Effect of Inlet Distortion Features on Transonic Fan Rotor Stall
,”
ASME
Paper No. GT2017-64612.
13.
Arend
,
D. J.
,
Wolter
,
J. D.
,
Hirt
,
S. R.
,
Provenza
,
A. J.
,
Gazzaniga
,
J. A.
,
Cousins
,
W. T.
,
Hardin
,
L. W.
, and
Sharma
,
O. P.
,
2017
, “
Experimental Evaluation of an Embedded Boundary Layer Ingesting Propulsor for Highly Efficient Subsonic Cruise Aircraft
,”
AIAA
Paper No. 2017-5041.
14.
Salta
,
C. A.
, and
Kroger
,
D. G.
,
1995
, “
Effect of Inlet Distortions on Fan Performance in Forced Draught Air-Cooled Heat Exchangers
,”
Heat Recovery Syst. CHP
,
15
(
6
), pp.
555
561
.
15.
Murphy
,
J.
,
2008
, “
Intake Ground Vortex Aerodynamics
,”
Ph.D. thesis
, Cranfield University, Bedford, UK.http://hdl.handle.net/1826/3515
16.
Horvath
,
N. R.
,
2013
, “
Inlet Vortex Formation Under Crosswind Conditions
,” M.S. thesis, Worcester Polytechnic Institute, Worcester, MA.
17.
Sayma
,
A. I.
,
Vahdati
,
M.
,
Sbardella
,
L.
, and
Imregun
,
M.
,
2000
, “
Modeling of Three-Dimensional Viscous Compressible Turbomachinery Flows Using Unstructured Hybrid Grids
,”
AIAA J.
,
38
(
6
), pp.
945
954
.
18.
Spalart
,
P. R.
, and
Allmaras
,
S. R.
,
1992
, “
A One-Equation Turbulence Model for Aerodynamic Flows
,”
AIAA
Paper No. 92-0439.
19.
Li
,
M.
,
Lipeng
,
L.
,
Jian
,
F.
, and
Qiuhui
,
W.
,
2014
, “
A Study on Turbulence Transportation and Modification of Spalart–Allmaras Model for Shock-Wave/Turbulent Boundary Layer Interaction Flow
,”
Chin. J. Aeronaut.
,
27
(
2
), pp.
200
209
.
20.
Liu
,
Y.
,
Lu
,
L.
,
Fang
,
L.
, and
Gao
,
F.
,
2011
, “
Modification of Spalart–Allmaras Model With Consideration of Turbulence Energy Backscatter Using Velocity Helicity
,”
Phys. Lett.
,
375
(
24
), pp.
2377
2381
.
21.
Lee
,
K.-B.
,
Wilson
,
M.
, and
Vahdati
,
M.
,
2018
, “
Validation of a Numerical Model for Predicting Stalled Flows in a Low-Speed Fan—Part I: Modification of Spalart–Allmaras Turbulence Model
,”
ASME J. Turbomach.
,
140
(
5
), p.
051008
.
22.
Lee
,
K.-B.
,
Dodds
,
J.
,
Wilson
,
M.
, and
Vahdati
,
M.
,
2018
, “
Validation of a Numerical Model for Predicting Stalled Flows in a Low-Speed Fan—Part II: Unsteady Analysis
,”
ASME J. Turbomach.
,
140
(
5
), p.
051009
.
23.
Dodds
,
J.
, and
Vahdati
,
M.
,
2015
, “
Rotating Stall Observations in a High Speed Compressor—Part II: Numerical Study
,”
ASME J. Turbomach.
,
137
(
5
), p.
051003
.
24.
Choi
,
M.
,
Vahdati
,
M.
, and
Imregun
,
M.
,
2011
, “
Effects of Fan Speed on Rotating Stall Inception and Recovery
,”
ASME J. Turbomach.
,
133
(
4
), p.
041013
.
25.
Vahdati
,
M.
, and
Cumpsty
,
N.
,
2015
, “
Aeroelastic Instability in Transonic Fans
,”
ASME J. Eng. Gas Turbines Power
,
138
(
2
), p.
022604
.
26.
Lee
,
K.-B.
,
Wilson
,
M.
, and
Vahdati
,
M.
,
2017
, “
Numerical Study on Aeroelastic Instability for a Low Speed Fan
,”
ASME J. Turbomach.
,
139
(
7
), p.
071004
.
27.
Stapelfeldt
,
S. C.
,
Parry
,
A. B.
, and
Vahdati
,
M.
,
2016
, “
Investigation of Flutter Mechanisms of a Contra-Rotating Open Rotor
,”
ASME J. Turbomach.
,
138
(
5
), p.
051009
.
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