In a boundary layer ingesting (BLI) fan system, the inlet flow field is highly nonuniform. In this environment, an axisymmetric stator design suffers from a nonuniform distribution of hub separations, increased wake thicknesses, and casing losses. These additional loss sources can be reduced using a nonaxisymmetric design that is tuned to the radial and circumferential flow variations at exit from the rotor. In this paper, a nonaxisymmetric design approach is described for the stator of a low-speed BLI fan. First, sectional design changes are applied at each radial and circumferential location. Next, this approach is combined with the application of nonaxisymmetric lean. The designs were tested computationally using full-annulus unsteady computational fluid dynamics (CFD) of the complete fan stage with a representative inlet distortion. The final design has also been manufactured and tested experimentally. The results show that a 2D sectional approach can be applied nonaxisymmetrically to reduce incidence and diffusion factor at each location. This leads to reduced loss, particularly at the casing and midspan, but it does not eliminate the hub separations that are present within highly distorted regions of the annulus. These are relieved by nonaxisymmetric lean where the pressure surface is inclined toward the hub. For the final design, the loss in the stator blades operating with BLI was measured to be 10% lower than that for the original stator design operating with undistorted inflow. Overall, the results demonstrate that the nonaxisymmetric design has the potential to eliminate any additional loss in a BLI fan stator caused by the nonuniform ingested flow field.

References

References
1.
Gunn
,
E. J.
, and
Hall
,
C. A.
,
2014
, “
Aerodynamics of Boundary Layer Ingesting Fans
,”
Proceedings of ASME Turbo Expo 2016
,
Dusseldorf, Germany
, ASME Paper No. GT2014-26142.
2.
Florea
,
R. V.
,
Voytovych
,
D.
,
Tillman
,
G.
,
Stucky
,
M.
,
Shabbir
,
A.
,
Sharma
,
O.
, and
Arend
,
D. J.
,
2013
, “
Aerodynamic Analysis of a Boundary-Layer-Ingesting Distortion-Tolerant Fan
,”
Proceedings of ASME Turbo Expo 2013
,
San Antonio, TX
, ASME Paper No. GT2013-94656.
3.
Wartzek
,
F.
,
Schiffer
,
H.-P.
,
Haug
,
J. P.
,
Niehuis
,
R.
,
Bitter
,
M.
, and
Kahler
,
C. J.
,
2016
, “
Investigation of Engine Distortion Interaction
,”
Proceedings of ASME Turbo Expo 2016
,
Seoul, Korea
, ASME Paper No. GT2016-56208.
4.
Jerez Fidalgo
,
V.
,
Hall
,
C. A.
, and
Colin
,
Y.
,
2012
, “
A Study of Fan-Distortion Interaction Within the NASA Rotor 67 Transonic Stage
,”
ASME J. Turbomach.
,
134
(
5
), p.
051011
.
5.
Parry
,
A.
,
1996
, “
Optimisation of Bypass Fan Outlet Guide Vanes
,”
ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition
,
Birmingham
,
Jun. 10–13
, Paper No. 96-GT-433, pp. 1–8
.
6.
Hall
,
D. K.
,
Greitzer
,
E. M.
, and
Tan
,
C. S.
,
2017
, “
Analysis of Fan Stage Design Attributes for Boundary Layer Ingestion
,”
ASME J. Turbomach.
,
139
(
7
), p.
071012
.
7.
Perovic
,
D.
,
Hall
,
C. A.
, and
Gunn
,
E. J.
,
2015
. “
Stall Inception in a Boundary Layer Ingesting Fan
,”
Proceedings of ASME Turbo Expo 2015
,
Montreal, Canada
, ASME Paper No. GT2015-43025.
8.
Madani
,
V.
, and
Hynes
,
T. P.
,
2009
, “
Boundary Layer Ingesting Intakes: Design and Optimization
,”
Proceedings of XIX International Symposium on Air Breathing Engines
, ISABE Paper No. 2009-1346.
9.
Brandvik
,
T.
, and
Pullan
,
G.
,
2011
, “
An Accelerated 3D Navier–Stokes Solver for Flows in Turbomachines
,”
ASME J. Turbomach.
,
133
(
2
), p.
021025
.
10.
Spalart
,
P. R.
, and
Allmaras
,
S. R.
,
1994
, “
A One-Equation Turbulence Model for Aerodynamic Flows
,”
La Recherche Aérospatiale
,
1
(
1
), pp.
5
21
.
11.
Shahpar
,
S.
, and
Lapworth
,
L.
,
2003
, “
PADRAM: Parametric Design and Rapid Meshing System for Turbomachinery Optimisation
,”
Proceedings of ASME Turbo Expo 2003
, ASME Paper No. GT2003-38698.
12.
Jacobs
,
E. N.
,
Ward
,
K. E.
, and
Pinkerton
,
R. M.
,
1933
, “
The Characteristics of 78 Related Airfoil Sections From Tests in the Variable-Density Wind Tunnel
,”
National Advisory Committee for Aeronautics
, Report No. 460.
13.
Lieblein
,
S.
,
Schwenk
,
F. C.
, and
Broderick
,
R. L.
,
1953
, “
Diffusion Factor for Estimating Losses and Limiting Blade Loadings in Axial-Flow-Compressor Blade Elements
,”
National Advisory Committee for Aeronautics (NACA) Research Memorandum
, NACA Paper No. RM E53D01.
14.
Denton
,
J. D.
,
2002
, “
The Effects of Lean and Sweep on Transonic Fan Performance: A Computational Study
,”
TASK Q.
,
6
(
1
), pp.
7
24
.
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