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Transcript of 0 , # - / * 1turbo.mech.iwate-u.ac.jp/Fel/papers/turbomachinery2008Yuan.pdf · / Mu r t h yáL a ks...
Studies on Aero-Thermal Performance of a Cooling Fan Used in a Narrow Space
Experiment and Numerical Analyses on Time-Averaged Characteristics
*
Hongbin YUAN, Ken-ichi FUNAZAKI, Kazutoyo YAMADA, Takashi SHIMADA
Department of Mechanical Engineering, Iwate University, Ueda 4- 3-5,Morioka, Iwate, 020-8551,Japan
Flow field around an entire stage of an axial cooling fan is analyzed using the three-dimensional unsteady
Reynolds-averaged Navier-Stokes (RANS) equations with Shear Stress Transport (SST) turbulence model, aiming
at the investigation of the cooling performance of the fan. The main focus in this study is on the effect of the
distance between the cooling fan and the surface to be cooled. Detailed flow measurement is also executed using a
slant hot-wire probe to clarify time-resolved flow structure as well as turbulent flow characteristics contained in
the downstream flow of the fan. The numerical results are compared with the experimental data as well as the flow
field in the vicinity of the fan blades. This study reveals the important role of the fan-surface distance in terms of
flow rate and cooling performance.
Key Words: Axial- Cooling Fan, Slant Hot-Wire Anemometer, CFD, Turbulent Flow, Air-Cooled Target
m o d e l 1 0 1 0
m o d e l 1 0 1 3 A / D
m o d e l 1 0 2 0
V
j
Xj
cos = cos cos cos + j( ) + sin sin
E V
F1 F2
E , ,V( ) = E , ,V( ) E , ,V( ) F1 ,( ) F2 V( )
V
,
,
t r a n s i e n t r o t o r / s t a t o r
5 7 1 0- 5
3 6 0
0 . 8 8 , 1
1 0
1 0
p
2U
t
2
p U
t
Q AU
t Q
Va Vz
Vc Vr
R* = R Rh( ) Rt Rh( )
Rt = 3 7 m m Rh
= 1 3 m m
R* 1 . 0
G a p
b G a p
R* = 0 . 8
R* < 0 . 2
G a p
G a p 1 0 ,
- 0 . 2 R* 0 . 3 6
0 . 9 R* 1 . 1 G a p 2 0 , 3 0
G a p 1 0
( d )
( c )
M u r t h y , K . N . S . , a n d
L a k s h m i n a r a y a n a , B . , L a s e r
D o p p l e r V e l o c i m e t e r
M e a s u r e m e n t i n t h e T i p R e g i o n
o f a C o m p r e s s o r R o t o r , A I A A
J . , 2 4 ( 5 ) , 1 9 8 6 , p p . 8 0 7 - 8 1 4 .
,
, ,
B , 5 6 , 5 3 1
, 1 9 9 0 , 3 3 7 8
I n o u e , M . 2 , B e h a v i o r
o f T i p L e a k a g e F l o w B e h i n d a n
A x i a l C o m p r e s s o r R o t o r , A S M E
J o u r n a l o f E n g i n e e r i n g f o r
G a s T u r b i n e a n d P o w e r ,
V o l . 1 0 8 , 1 9 8 6 , p p . 7 - 1 4 .
,
C F D ,
, 2 0 0 6
A N S Y S C F X T h e o r y
D o c u m e n t a t i o n , A N S Y S
I n c . R e l e a s e 1 0 . 0 , W a t e r l o o ,
O n t a r i o , C a n a d a .
Fig.3 Wire-fixed coordinate system for slant-type hot-wire probe
Fig.4 Configuration of test tan and hot-wire probe traverse position
Fig.8. Averaged Velocity Distributions by EFD & CFD at Measurement location, (a)
Absolute velocity (b) Axial velocity (c) Circumferential velocity (d) Radial velocity
Fig.11 Limit streamline on suction side of the fan blade
(Left: gap=10; middle: gap=20; Right: gap=30)
T
L
V
Separation
T
L
V
Separation
T
L
V
Separation
Flow
(a) (b) View from position E
Fig. 9 Locations of cutting plane (a) Front View (b) Side View
C B D A
Observation
Region
Flow
E
out
out
in
in
(a) (b) (c) (d)
Flow
Casing
TLV TLV TLV Tip Tip Tip
TE TE TE
Casing
TLV
TLV TLV TLV Tip Tip Tip
TE TE TE
Tip Tip Tip
TLV TLV TLV
TE TE TE
LE LE LE
Casing
Separation
Separation
Separation
TLV TLV Tip Tip Tip TLV
Fig.10. Distribution of the axial velocity around blade tip at the observation cutting planes
(a) Plane A (b) Plane B; (c) Plane C; (d) Plane D; (Left: gap=10; Middle: gap=20; Right: gap=30)
Casing