Abstract

This paper elucidates the performance degradation and flow instability of an axial fan caused by the presence of disk-shaped obstacles upstream of the fan, such as wall surfaces. The increase in pressure loss and the decrease in shaft power coefficient due to inlet swirl flow, and the increase in pressure loss due to the outlet swirl flow, cause performance degradation. When the obstacle is closer to the fan, the strong swirl flow causes a negative pressure region between the fan and the obstacle, reversing the flow direction. This phenomenon is caused by the diffuser effect of the outward flow and the increase in pressure by acting as a multiblade centrifugal fan. At a low flow rate, a clockwise vortex is generated at the center of the obstacle and induces two counterclockwise rotating vortices. The vortices circumferentially separate the inward and outward flows along the fan's axis in a uniform manner, and their cores are circularly rotated by the clockwise vortex. These findings can contribute to the layout of fans under spatial restriction and suppression of flow instability due to obstacles.

References

References
1.
Kim
,
J.
,
Kim
,
J.
, and
Kim
,
K.
,
2011
, “
Axial-Flow Ventilation Fan Design Through Multi-Objective Optimization to Enhance Aerodynamic Performance
,”
ASME J. Fluids Eng.
,
133
(
10
), p.
101101
.10.1115/1.4004906
2.
Sørensen
,
D. N.
, and
Sørensen
,
J. N.
,
2000
, “
Toward Improved Rotor-Only Axial Fans—Part I: A Numerically Efficient Aerodynamic Model for Arbitrary Vortex Flow
,”
ASME J. Fluids Eng.
,
122
(
2
), pp.
318
323
.10.1115/1.483275
3.
Sørensen
,
D. N.
,
Thompson
,
M. C.
, and
Sørensen
,
J. N.
,
2000
, “
Toward Improved Rotor-Only Axial Fans—Part II: Design Optimization for Maximum Efficiency
,”
ASME J. Fluids Eng.
,
122
(
2
), pp.
324
329
.10.1115/1.483260
4.
Reese
,
H.
,
Kato
,
C.
, and
Thomas
,
H. C.
,
2007
, “
Large Eddy Simulation of Acoustical Sources in a Low Pressure Axial-Flow Fan Encountering Highly Turbulent
,”
ASME J. Fluids Eng.
,
129
(
3
), pp.
263
272
.10.1115/1.2427077
5.
Zhang
,
W.
, and
Vahdati
,
M.
,
2019
, “
A Parametric Study of the Effects of Inlet Distortion on Fan Aerodynamic Stability
,”
ASME J. Turbomach.
,
141
(
1
), p.
011011
.10.1115/1.4041376
6.
Liu
,
P.
,
Shiomi
,
N.
,
Kinoue
,
Y.
,
Setoguchi
,
T.
, and
Jin
,
Y.
,
2014
, “
Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-Opened Axial Fan
,”
Int. J. Fluid Mach. Syst.
,
7
(
2
), pp.
60
67
.10.5293/IJFMS.2014.7.2.060
7.
Nakamura
,
H.
,
Fukue
,
T.
,
Koizumi
,
K.
, and
Ishizuka
,
M.
,
2010
, “
Reduction in Flow Rate of Small Cooling Fans by an Obstruction
,”
Trans. Jpn. Soc. Mech. Eng., Ser. B
,
76
(
768
), pp.
64
70
(in Japanese).10.1299/kikaib.76.768_1184
8.
Kawaguchi
,
K.
,
Okui
,
K.
, and
Kuwaumi
,
M.
,
2006
, “
Effects of Turbulence of Inlet Flow on Performance of Compact Axial Flow Fan (Effects of Turbulence Generated by Obstacle on Fan Characteristics and Noise
,”
J. Turbomach. Soc. Jpn.
,
35
(
8
), pp.
32
40
(in Japanese).10.11458/tsj.35.480
9.
Taniguchi
,
H.
,
Funazaki
,
K.
,
Takahashi
,
T.
, and
Chiba
,
K.
,
2011
, “
Unsteady Flow Field and Noise Characteristics of a Small Axial Flow Fan Used in Narrow Space
,”
J. Turbomach. Soc. Jpn.
,
2011
(
46
), pp.
20
58
(in Japanese).10.1299/jsmeth.2011.46.20
10.
Lin
,
S.
, and
Chou
,
C.
,
2004
, “
Blockage Effect of Axial-Flow Fans Applied on Heat Sink Assembly
,”
Appl. Therm. Eng.
,
24
(
16
), pp.
2375
2389
.10.1016/j.applthermaleng.2004.03.009
11.
Sui
,
D.
,
Wang
,
S. S.
,
Mao
,
J. R.
,
Kim
,
T.
, and
Lu
,
T. J.
,
2009
, “
Exit Flow Behavior of Axial Fan Flows With/Without Impingement
,”
ASME J. Fluids Eng.
,
131
(
6
), p.
061103
.10.1115/1.3130246
12.
Fernández Oro
,
J. M.
,
Argüelles Díaz
,
K. M.
,
Santolaria Morros
,
C.
, and
Blanco Marigorta
,
E.
,
2007
, “
Unsteady Flow and Wake Transport in a Low-Speed Axial Fan With Inlet Guide Vanes
,”
ASME J. Fluids Eng.
,
129
(
8
), pp.
1015
1029
.10.1115/1.2746920
13.
Fernández Oro
,
J. M.
,
Ballesteros-Tajadura
,
R.
,
Blanco Marigorta
,
E.
,
Argüelles Díaz
,
K. M.
, and
Santolaria Morros
,
C.
,
2008
, “
Turbulence and Secondary Flows in an Axial Flow Fan With Variable Pitch Blades
,”
ASME J. Fluids Eng.
,
130
(
4
), p.
041101
.10.1115/1.2903523
14.
Yen
,
S. C.
, and
Lin
,
F. K. T.
,
2006
, “
Exit Flow Field and Performance of Axial Flow Fans
,”
ASME J. Fluids Eng.
,
128
(
2
), pp.
332
340
.10.1115/1.2169809
15.
Salunkhe
,
P. B.
, and
Pradeep
,
A. M.
,
2010
, “
Stall Inception Mechanism in an Axial Flow Fan Under Clean and Distorted Inflows
,”
ASME J. Fluids Eng.
,
132
(
12
), p.
121102
.10.1115/1.4002921
16.
McDougall
,
N. M.
,
Cumpsty
,
N. A.
, and
Hynes
,
T. P.
,
1990
, “
Stall Inception in Axial Compressors
,”
ASME J. Turbomach.
,
112
(
1
), pp.
116
123
.10.1115/1.2927406
17.
Day
,
I. J.
,
1991
, “
Stall Inception in Axial Compressors
,”
ASME
Paper No. 91-GT-086. 10.11115/91-GT-086
18.
Jansen
,
W.
,
1964
, “
Rotating Stall in a Radial Vaneless Diffuser
,”
ASME J. Basic Eng.
,
86
(
4
), pp.
750
758
.10.1115/1.3655945
19.
Kinoshita
,
Y.
, and
Senoo
,
Y.
,
1985
, “
Rotating Stall Induced in Vaneless Diffusers of Very Low Specific Speed Centrifugal Blowers
,”
ASME J. Eng. Gas Turbines Power
,
107
(
2
), pp.
514
521
.10.1115/1.3239761
20.
Tsurusaki
,
H.
, and
Kinoshita
,
T.
,
2001
, “
Flow Control of Rotating Stall in a Radial Vaneless Diffuser
,”
ASME J. Fluids Eng.
,
123
(
2
), pp.
281
286
.10.1115/1.1351174
21.
Tsujimoto
,
Y.
,
Yoshida
,
Y.
, and
Mori
,
Y.
,
1996
, “
Study of Vaneless Diffuser Rotating Stall Based on Two-Dimensional Inviscid Flow Analysis
,”
ASME J. Fluids Eng.
,
118
(
1
), pp.
123
127
.10.1115/1.2817489
22.
Ljevar
,
S.
,
de Lange
,
H. C.
, and
van Steenhoven
,
A. A.
,
2006
, “
Two-Dimensional Rotating Stall Analysis in a Wide Vaneless Diffuser
,”
Int. J. Rotating Mach.
,
2006
, pp.
1
11
.10.1155/IJRM/2006/56420
23.
Nishibe
,
K.
,
Sato
,
K.
,
Tsujimoto
,
Y.
, and
Yoshiki
,
H.
,
2011
, “
Control of Flow Instabilities Downstream of Radial Inlet Guide Vanes
,”
J. Fluid Sci. Technol.
,
6
(
4
), pp.
651
661
.10.1299/jfst.6.651
24.
Abernethy
,
R. B.
,
Benedict
,
R. P.
, and
Dowdell
,
R. B.
,
1985
, “
ASME Measurement Uncertainty
,”
ASME J. Fluids Eng.
,
107
(
2
), pp.
161
164
.10.1115/1.3242450
25.
Liang
,
H. Z.
, and
Maxworthy
,
T.
,
2005
, “
An Experimental Investigation of Swirling Jets
,”
J. Fluid Mech.
,
525
, pp.
115
159
.10.1017/S0022112004002629
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