Abstract

In the present experimental study, a low aspect ratio, low hub-tip ratio contra-rotating axial fan is investigated to understand its performance under windmilling conditions. Two configurations are tested; in the first configuration (event A), the front rotor of the contra-rotating fan is powered and the rear rotor is allowed to windmill; in the second configuration (event B), the rear rotor of the contra-rotating fan is powered and the front rotor is allowed to windmill. The spanwise distribution of the loading coefficient and the flow angles at different streamwise positions reveal the details of the flow development across the rotors. Though the average total pressure drops across the windmilling rotor for both the events, a small spanwise region behaves as a fan or a stirrer. Thus, a “neutral radius” on the windmilling rotor is identified for both events A and B. The neutral radius appears close to the tip for event A and it appears close to the hub for event B. Thus, the span regions close to the tip behave as a fan for event A and the span regions close to the hub behave as a stirrer for event B. It is also observed that the neutral radius shifts to a lower span location as the flow coefficient reduces. Thus, the flow coefficient is a significant parameter that decides the position of the neutral radius. Further, the unsteady pressure measurements recorded at the casing capture the fundamental phenomena during the stall inception. The paper thus relates the similarities and unveils the contrasting features of the windmilling events A and B. In summary, this paper discusses the performance, flow physics, and stall inception characteristics of a contra-rotating axial fan under windmilling conditions.

References

1.
Choi
,
M.-S.
,
Kang
,
I.-S.
,
Lim
,
J.-S.
, and
Hong
,
Y.-S.
,
1997
, “
Analysis of Windmilling Characteristics for a Twin-Spool Turbofan Engine
,”
ASME
Paper No. 97-AA-113.10.1115/97-AA-113
2.
Shou
,
Z. Q.
,
1981
, “
Calculation of Windmilling Characteristics of Turbojet Engines
,”
ASME J. Eng. Power
,
103
(
1
), pp.
1
12
.10.1115/1.3230697
3.
Cyrus
,
V.
,
1990
, “
The Turbine Regime of a Rear Axial Compressor Stage
,”
ASME
Paper No. 90-GT-074.10.1115/90GT-074
4.
Choi
,
M. S.
,
Lim
,
J. S.
, and
Hong
,
Y. S.
,
1996
, “
A Practical Method for Predicting the Windmilling Characteristics of Simple Turbo Jet Engines
,”
ASME
Paper No. 96-TA-060.10.1115/96-TA-060
5.
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
6.
Goto
,
T.
,
Kato
,
D.
,
Ohta
,
Y.
, and
Outa
,
E.
,
2014
, “
Unsteady Flow Structure in an Axial Compressor at Windmill Condition
,”
ASME
Paper No. GT2014-25609.10.1115/GT2014-25609
7.
García Rosa
,
N.
,
Dufour
,
G.
,
Barènes
,
R.
, and
Lavergne
,
G.
,
2015
, “
Experimental Analysis of the Global Performance and the Flow Through a High-Bypass Turbofan in Windmilling Conditions
,”
ASME J. Turbomach.
,
137
(
5
), p. 051001.10.1115/1.4028647
8.
Binder
,
N.
,
Courty-Audren
,
S.-K.
,
Duplaa
,
S.
,
Dufour
,
G.
, and
Carbonneau
,
X.
,
2015
, “
Theoretical Analysis of the Aerodynamics of Low-Speed Fans in Free and Load-Controlled Windmilling Operation
,”
ASME J. Turbomach.
,
137
(
10
), p.
101001
.10.1115/1.4030308
9.
Gunn
,
E. J.
, and
Hall
,
C. A.
,
2016
, “
Loss and Deviation in Windmilling Fans
,”
ASME J. Turbomach.
,
138
(
10
), p.
101002
.10.1115/1.4033163
10.
Ortolan
,
A.
,
Courty-Audren
,
S.-K.
,
Binder
,
N.
,
Carbonneau
,
X.
,
Rosa
,
N. G.
, and
Challas
,
F.
,
2017
, “
Experimental and Numerical Flow Analysis of Low-Speed Fans at Highly Loaded Windmilling Conditions
,”
ASME J. Turbomach.
,
139
(
7
), p.
071009
.10.1115/1.4035656
11.
Ortolan
,
A.
,
Courty-Audren
,
S.-K.
,
Lagha
,
M.
,
Binder
,
N.
,
Carbonneau
,
X.
, and
Challas
,
F.
,
2018
, “
Generic Properties of Flows in Low-Speed Axial Fans Operating at Load-Controlled Windmill
,”
ASME J. Turbomach.
,
140
(
8
), p.
081002
.10.1115/1.4040678
12.
Manas
,
M. P.
, and
Pradeep
,
A. M.
,
2019
, “
Understanding Unsteady Flow Behaviour in a Contra-Rotating Axial Flow Fan Under Radially Distorted Inflow
,”
ASME
Paper No. GT2019-90252.10.1115/GT2019-90252
13.
Torrence
,
C.
, and
Compo
,
G. P.
,
1998
, “
A Practical Guide to Wavelet Analysis
,”
Bull. Am. Meteorol. Soc.
,
79
(
1
), pp.
61
78
.10.1175/1520-0477(1998)079<0061:APGTWA>2.0.CO;2
14.
Manas
,
M. P.
, and
Pradeep
,
A. M.
,
2020
, “
Stall Inception Mechanisms in a Contra-Rotating Fan Operating at Different Speed Combinations
,”
Proc. Inst. Mech. Eng., Part A
,
234
(
8
), pp.
1041
1052
.10.1177/0957650919893831
You do not currently have access to this content.