This paper reports on a theory for poststall transients in contra-rotating fans, which is developed from the basic Moore–Greitzer theory. A second-order hysteresis term is assumed for the fan pressure rise, which gives the theory more capabilities in predicting the fan instabilities. The effect of the rotational speed ratio of the two counter rotating rotors on the fan performance during the occurrence of surge and rotating stall are studied (the rotational speed of the front rotor is assumed to be kept constant whereas the speed of the rear rotor is variable). One of the new capabilities of the current model is the possibility of investigating the effect of the initial slope on the fan characteristic. Results reveal that unlike the conventional fans and compressors, in the current contra-rotating fan stall cannot be initiated from the negative slope portion of the fan pressure rise characteristic curve. One of the important advantages of the developed model is that it enables investigation of the effect of the rate of throttling on the instabilities. Results show that more the rotational speed of the rear rotor, the more robust to surge (caused by throttling) the fan is.

References

References
1.
Lesley
,
E.
,
1933
, “
Experiments With a Counter-Propeller
,” Technical Report, National Advisory Committee for Aeronautics, Washington, DC, Report No. 453.
2.
Lesley
,
E.
,
1939
, “
Tandem Air Propellers
,” Technical Report, National Advisory Committee for Aeronautics, Washington, DC, Report No. 689.
3.
Sharma
,
P. B.
,
Jain
,
Y. P.
, and
Pundhir
,
D. S.
,
1988
, “
A Study of Some Factors Affecting the Performance of a Contra-Rotating Axial Compressor Stage
,”
Proc. Inst. Mech. Eng., Part A
,
202
(
1
), pp.
15
21
.
4.
Nouri
,
H.
,
Ravelet
,
F.
,
Bakir
,
F.
,
Sarraf
,
C.
, and
Rey
,
R.
,
2012
, “
Design and Experimental Validation of a Ducted Counter-Rotating Axial-Flow Fans System
,”
ASME J. Fluids Eng.
,
134
(
10
), p.
104504
.
5.
Mistry
,
C.
, and
Pradeep
,
A. M.
,
2013
, “
Effect of Variation in Axial Spacing and Rotor Speed Combinations on the Performance of a High Aspect Ratio Contra-Rotating Axial Fan Stage
,”
Proc. Inst. Mech. Eng., Part A
,
227
(
2
), pp.
138
146
.
6.
Wang
,
Z.
,
Yuan
,
W.
,
Li
,
Q.
, and
Lu
,
Y.
,
2012
, “
Experimental Investigation on the Stall Inception of a Counter-Rotating Compressor
,”
ASME
Paper No. GT2012-68235.
7.
Dejene Toge
,
T.
, and
Pradeep
,
A. M.
,
2015
, “
Experimental Investigation of Stall Inception Mechanisms of Low Speed Contra Rotating Axial Flow Fan Stage
,”
Int. J. Rotating Mach.
,
2015
, p.
641601
.
8.
Gao
,
L.
,
Li
,
X.
,
Xie
,
J.
, and
Liu
,
B.
,
2012
, “
The Effect of Speed Ratio on the First Rotating Stall Stage in Contra-Rotating Compressor
,”
ASME
Paper No. GT2012-68802.
9.
Gao
,
L.
,
Li
,
R.
,
Miao
,
F.
, and
Cai
,
Y.
,
2015
, “
Unsteady Investigation on Tip Flow Field and Rotating Stall in Counter-Rotating Axial Compressor
,”
ASME J. Eng. Gas Turbines Power
,
137
(
7
), p.
072603
.
10.
Mao
,
X.
, and
Liu
,
B.
,
2016
, “
Numerical Study of the Unsteady Behaviors and Rotating Stall Inception Process in a Counter-Rotating Axial Compressor
,”
Proc. Inst. Mech. Eng., Part G
,
230
(
14
), pp.
2716
2727
.
11.
Emmons
,
H. W.
,
Pearson
,
C. E.
, and
Grant
,
H. P.
, 1955, “
Compressor Surge and Stall Propagation
,”
Trans. ASME
,
77
(4), pp. 455–469.
12.
Stenning
,
A. H.
,
Kriebel
,
A. R.
, and
Montgomery
,
S. R.
,
1956
, “
Stall Propagation in Axial-Flow Compressors
,” National Advisory Committee for Aeronautics, Washington DC, Report No. 3580.
13.
Takata
,
H.
, and
Nagano
,
S.
,
1972
, “
Nonlinear Analysis of Rotating Stall
,”
J. Eng. Power
,
94
(
4
), pp.
279
293
.
14.
Cumpsty
,
N. A.
, and
Greitzer
,
E. M.
,
1981
, “
A Simple Model for Compressor Stall Cell Propagation
,” ASME Paper No. 81-GT-73.
15.
Moore
,
F. K.
,
1984
, “
A Theory of Rotating Stall of Multistage Axial Compressors—Part I: Small Disturbances
,”
ASME J. Eng. Gas Turbines Power
,
106
(
2
), pp.
313
320
.
16.
Moore
,
F. K.
, and
Greitzer
,
E. M.
,
1986
, “
A Theory of Post-Stall Transients in Axial Compression Systems: Part I—Development of Equations
,”
ASME J. Eng. Gas Turbines Power
,
108
(
1
), pp.
68
76
.
17.
Roy
,
B.
,
Ravibabu
,
K.
,
Rao
,
P. S.
,
Basu
,
S.
,
Raju
,
A.
, and
Murthy
,
P. N.
,
1992
, “
Flow Studies in Ducted Twin-Rotor Contra-Rotating Axial Flow Fans
,”
ASME
Paper No. 92-GT-390.
18.
Jackson
,
A. D.
,
1986
, “
Stall Cell Development in an Axial Compressor
,” ASME Paper No. 86-GT-249.
19.
Camp
,
T. R.
, and
Day
,
I. J.
,
1998
, “
1997 Best Paper Award—Turbomachinery Committee: A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor
,”
ASME J. Turbomach.
,
120
(
3
), pp.
393
401
.
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