Engineering, 2010, 2, 550-557
doi:10.4236/eng.2010.27071 Published Online July 2010 (http://www.SciRP.org/journal/eng)
Investigation of Stator Wake Variability in Single Stage
Axial-Compressor
Xiaorong Xiang, Bo Liu, Liqing Qiao, Qingwei Wang
School of Power and Energy, Northwestern Polytechnical University, Xi’an, China
Received April 22, 2010; revised June 22, 2010; accepted June 22, 2010
Abstract
In this paper, we investigate the stator wake variability along the axial direction under different rotating
speeds and mass flow conditions, in the terms of wake-core position, wake depth, wake width and wake ve-
locity gradient. Experimental study is carried out in a single stage axial compressor by using Hot-wire Ane-
mometer (HWA). Simultaneously, the numerical calculation is brought out in the same experiment rig.
Firstly, we analyze the time-averaged velocity and radial vorticity at different axial positions, and explore the
wake variability along the axial direction. Then, we present the effects of operation conditions on the
wake-core position, and find out the inlet Mach number and incident angle are both the key influence factors
of the wake-core position. Finally, we summarize four preliminary conclusions of the wake variability.
Keywords: Axial-Flow, Compressor, Wake, Hot-Wire Anemometer (HWA), Vorticity
1. Introduction
In the turbo-machine, when the boundary layers, on the
blade suction and pressure surface, meet at the trail edge,
the mixing area with total pressure and velocity loss
forms the wake region. In the multistage turbo-machine,
the downstream rows will be influenced by the wake of
the upstream rows and appear unsteady effect, then it
causes to the aero-dynamical and flow characteristic
variation, and plays an important role in the flow loss of
the turbo-machine [1-3]. So, it is very significative to
bring out further research of the wake flow characteristic
in the turbo-machine, for th e further purpose to study the
unsteady effect, control the flow loss, and improve effi-
ciency of the turbo-machine. Presently, abundant inves-
tigations of the wake flow mainly focus on the genera-
tion and development of the wake vortex structure [4-6],
also on the unsteady effect of the wake flow to the
downstream rows [7-9]. But, few research works have
been brought out on the influence factors of the wake
configuration. Nicole L. Key [10] etc have brought out
some experimental studies of the variation orderliness of
the rotor wake in a three stages axial-compressor, espe-
cially analyzed the influence of the rows interaction on
the rotor wake flow under the designed and high-load
operation conditions. S. T. Hsu [11] etc have measured
the rotor wake flow of a single stage axial-compressor
including inlet guide vane, and studied the variation of
the wake configuration along with the adjustment of the
axial gap between the rotor and stator rows, under the
designed and hig h-load operation conditions respectively.
The above two research works all indicate that the varia-
tion of the operation conditio ns and rows interactio n play
a very important role of the wake configuration trans-
formation. So that it is very important and necessary in
the theory and engineering field, to bring out further in-
vestigation of the statistic aero-kinematic parameters
variation of the axial-compressor wake region under dif-
ferent operation cond itions.
In this paper, investigation was carried out on the
wake variability along the axial direction under different
rotating speeds and mass flow conditions. Experimental
study of the stator blade wake in a single stage axial flow
compressor was carried out by using Hot-wire Ane-
mometer (HWA). Simultaneously, the numerical re-
search was brought out in the same experiment rig. Ex-
periment was taken at the 7.6%, 15.2%, 30.3% and
45.5% stator chord downstream to the trail edge respec-
tively. The statistic aero-kinematic parameters, including
time-averaged velocity and the radial vorticity, were
analyzed for the purpose to summarize the wake vari-
ability under different operation conditions. The research
results can provide experimental and numerical reference
for the further investigation of the wake unsteady effect
to the downstrea m rows and flow loss con trol in th e mul-

X. R. XIANG ET AL.551
tistage axial-compressor under the designed and off-de-
signed operation conditions.
2. Experimental Equipment and Scheme
2.1. Experimental Equipment Introduction
Figure 1 is a sketch of the experimental rig and the
Hot-wire Anemometer (HWA) system. The experimental
rig is a single stage axial-compressor including the
transparent shroud, and it is driven by a three-phase
asynchronous motor. Through the transducer to change
the power frequency (0~50 Hz), the rotating speed can be
adjusted from 0 to 3000 rpm continuously. The com-
pressor mass flow can be adjusted by ro tating the throttle
at the outlet.
For the HWA test probe is fixed on the top of the
shroud, it just can move in the radial and axial d irection.
In order to measure the velocity downstream to the stator
trail edge across one cascade spacing, the stator row in
this compressor was designed to be capable rotating
across two cascade spacing by adjusting the strut fixed
on the stator hub. Table 1 presents the basic parameters
of this compressor.
Hot-wire Anemometer (HWA), used in this research
work, is the production of the DANTEC Company in
Danmark. In the experiment, choosing an X-array probe
55P54 as the test probe, and choosing NI PCI 6040E as
the A/D board. The velocity and direction calibration of
the dual-sensor probe is carried out the calibration
wind-tunnel. According to the numerical simulation re-
sults, the stator downstream velocity is about 1 m/s to 18
m/s under the different operation conditions in this ex-
periment, and the flow stream yaw angles, relating to the
axial direction, are all below 40 degree. So, in the cali-
bration choosing the velocity range 0.5~22 m/s, and the
yaw angle range –40°~40 °. The calibration curves just as
shown in the Figure 2 and Figure 3.
Figure 1. Sketch of axial-compressor and HWA system.
Table 1. Basic parameter of axial-compressor.
Rotating
Speed Shroud Diameter Rotor Tip Gap Rotor Blade Number Rotor Hub Ratio
r/min mm mm
0~3000383 7.5 6 0.351
Stator
Chord Stator Insta lla- tion Angle Stator Tip Gap Stator Blade Number Stator Hub Ratio
mm °(degree) mm
66 22.9 3~5 13 0.351~0.376
Velocity(m/s)
Voltage (V)
0246810 12 14 16 18 20 22 24
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
Wire 2
Wire 1
Figure 2. Velocity calibration curve of 55P54 probe.
Yaw Angle (Degree)
Voltage(V)
-40 -30 -20 -10010 20 30 40
1.7
1.75
1.8
1.85
1.9
1.95
2
2.05
2.1
2.15
2.2
2.25
2.3
2.35
2.4
Wire 2
Wire 1
Figure 3. Direction calibration curve of 55P54 probe.
2.2. Experimental Scheme
In this research work, the rotating speeds are respectively:

X. R. XIANG ET AL. 552
n1 = 1000 r/min, n2 =1500 r/min, n3 = 2000 r/min, n4 =
2500 r/min, the throttle angles are respectively: α1 = 0°,
α2 = 20°, α3 = 30°, α4 = 40°. The atmosphere conditions
are: p0 = 0.9771 × 105 Pa, T0 = 284.05 K.
In order to unify the operation condition of the nu-
merical calculation and experiment, outlet static pressure
p2 needs to be measured under different rotating speeds
and throttle angles, just as shown in Table 2.
Because of the spatial constraint of the experiment rig
that the struts are too close to the stator, the test position
along the axial dir ection choosing z1 = 7.6%, z2 = 15.2%,
z3 = 30.3% and z4 = 45.5% stator chord downstream to
the trail edge, at 50% span-wise section.
The HWA test probe is fixed on the shroud, so the tan-
gential position of the test probe is immovable. In order
to measure the velocity across one cascade spacing, it is
practicable to rotate the stato r in the tangential direction.
The tangential measure position is chosen just as shown
in the Figures 4 and 5, it is 0.5 cascade spacing on both
sides of the Stator Blade-2. The cascade spacing in the
tangential direction is about 27.7°, and n (= 75) measure
points is chosen in this direction.
The HWA sampling frequency is 1 × 104 Hz, sampling
time is 1 s. In order to eliminate the sampling stochastic
error, the velocity measurement repeats m (= 10) times
on each test point. After been time averaged, the time-
averaged velocities are av eraged by the below formula:
,
11, 2,,
m
kik
i
EEmk


n (1)
Table 2. Outlet static pressure under different operation
conditions.
(α1 = 0°) 1000 rpm 1500 rpm 2000 rpm 2500 rpm
p2 (Pa) 97734.7 97762.3 97800.4 97849.6
(2000
rpm) α1 = 0° α2 = 20° α3 = 30° α4 = 40°
p2 (Pa) 97800.4 97812.6 97826.7 97842.3
Figure 4. Sketch of tangential measure point in cross section.
Figure 5. Sketch of stator setting position and tangential
measure point in revolution surface.
Under the different operation conditions, the relative
standard variances of the time-averaged velocities at dif-
ferent test point are almost less than 5%. In order to
eliminate the high-frequency electromagnetic signal
coming from the motor and the transducer, we connect
the motor and the transducer to the gro und.
3. Numerical Simulation Method
The three-dimensional numerical simulation was carried
out through applying the NUMECA FINE/TURBO com-
mercial software package, in which the Favre-Reynolds
averaged Navier-Stokes equations were discretized by
using a cell-center explicit finite volume scheme accord-
ing to Jameson et al. [12]. And the single equation tur-
bulence model Spalart-Allmaras was chosen to estimate
the eddy viscosity. The structural grids, used for the nu-
merical simulation, contained three different topologies
as shown in Figure 6. The body-fitted C-type grid to-
pology was used for all the blades, while the H-type grid
topology for the main flow region. The butterfly grid
topology was chosen for the blade tip gap, the inlet and
outlet fairing. In order to consider the influence of the
struts at the stator downstream, the struts were dealt with
as the stator blades, and calculated together with the ro-
tor and stator upstream. The outlet static p ressure was set
according to the value in Table 2 under different rotating
speeds and throttle angles.
The total grid nodes number of this single axial-com-
pressor, including the struts, were approximat ely 1700 000.
Figure 6. The surface grids of the axial-compressor.

X. R. XIANG ET AL.553
4. Experimental and Numerical Results
In this section, analysis was brought out on the variation
of the wake-core position, wake depth, wake width and
wake velocity gradient under the different rotating
speeds and mass flow conditions. Just in order to sum-
marize the stator wake variability under the different
operation conditions.
4.1. Wake Variability along Axial Direction
In this subsection, all the results are under n
1 rotating
speed, α1 throttle angle, and on the 50% span-wise sec-
tion.
Figure 7 gives out the time-averaged axial and tan-
gential velocity in the wake region at z1 axial position.
The solid line represents the nu merical simulation results,
while the square point represents the test results. From
this figure, we can find out that the numerical and ex-
perimental results show the similar variation orderliness:
the velocity is nearly un changed in the free stream region,
while appears decrease in the wake region, and the ve-
locity on the wake pressure side reduces more quickly
than the wake suction side. The experimental axial ve-
locity value is a little bigger than the numerical result.
The tested tangential velocity is very close to the nu-
merical result outside the wake region, while the tested
wake depth is larger than the numerical result.
From Figure 8, we can find out that the wake-core
position moves to the suction side gradually along the
axial direction, the wake becomes much flatter along
with it becomes much wider. The time-averaged velocity,
outside the wake region, is nearly unchanged.
For the purpose to study the wake-core position and
Tangential Position (Degree)
Velocity(m/s)
048 12 16 20 24 28
-1
1
3
5
7
9
11
13
15
17
19
Cal.
Exp.
SSPS
V
U


n1= 1000 rpm
Figure 7. Comparison of mean velocity between the ex-
perimental and numerical results.
Tangential Position (Degree)
Velocity (m/s)
048 12 16 20 24 28
-1
1
3
5
7
9
11
13
15
17
19
z1=45.5%
z1=7.6%
z2=15.2%
z3=30.3%
SS
PS
V
U


n1=1000rpm
Figure 8. Variation of mean velocity at different axial posi-
tions (Experimental results).
depth variability more intuitionistic, it is necessary to
bring out the variation curve of the wake-core position
and velocity along the axial direction, just as shown in
Figure 9. For the experimental results, since the spatial
limit of the experiment rip, the shortest distance to the
stator trail edge is restricted to 7.6% chord. For numeri-
cal results, because of the position limit of the ro-
tor/stator interface between the stator row and the Strut 1,
the longest distance is restricted to 30.3% chord. From
this figure, we can find out that the gaps between the
tested and numerical results in the terms of the wake-
core position and wake-core tangential velocity are quite
small. Exceptionally, the tested wake-core axial velocity
Z(%Chord)
Tangential Position (Degree)
Velocity (m/s)
06 12 18 24 30 36 42 48
0
2
4
6
8
10
12
14
16
18
20
22
24
-2
-1
0
1
2
3
4
5
6
7
8
9
10
VExp.
UCal.
UExp.
VCal.
Velocity
Position
n1=1000rpm


Figure 9. Variation of wake-core position and velocity at
different axial positions.

X. R. XIANG ET AL. 554
is bigger than the numerical one. From the variation
curve of the wake-core position, it can be found that the
wake-core moves to the wake suction side gradually
along the axial direction, and the variation curve is
nearly linear.
In this paper, we consider the link of the wake-core
along the axial direction as the Wake-core Line, and
consider the yaw angle between the wake-core line and
the axial direction as the Wake-core Yaw Angle. From
the Figure 9, it can also be found that the Wake-core
Line of the axial velocity is always below the tangential
velocity one, but the Wake-core Yaw Angles are almost
the same. Since the velocity outside the wake region is
nearly unchanged at different axial positions, the high
wake-core velocity represents to the small wake depth.
The variation curve of the wake-core velocity reflects
that the wake depth decreases gradually along the axial
direction, because of the influence of the mix of the main
flow and the wake, and the decrement of the axial wake
depth is larger than the tangential one. Furthermore, the
gradient of the wake-core velocity also decreases along
the axial direction.
The wake velocity gradient can obviously reflect the
position of the velocity inflexion which represents the
unsteady poin t of the wake flow [9], so it is necessary to
bring out the analysis of the wake velocity gradient, for
the purpose to study the wake variability much deeply.
The radial Vorti ci ty is defined by the below formula:
yVz Ux

  (2)
In the formula,
y

represents the radial vorticity,
represents tangential velocity, U represents the axial
velocity, x, y, z represents th e tangential, radial and axial
direction respectively.
V
For the tangential velocity is nearly unchanged in the
main flow region, that is the Vz nearly equals to
zero. In the wake region, Vz is also quite smaller
compared to the Ux . So, the value of the
y

is
mainly influenced by the Ux. From the transforma-
tion of the radial vorticity, we can approximately sum-
marize the variation orderliness of the velocity gradient
in the wake region.
Figure 10 gives out the radial vorticity contours in the
wake region. In this figure, the zero vorticity line repre-
sents the Wake-core Line of the axial velocity, and its
transformation is consistent to the Figure 9. On both
sides of the zero line, there are two extremum points at
the same axial position, one is positive on the wake
pressure side, while the other is negative on the suction
side, and the negative one is smaller than the positive one.
Along the axial direction, the two extremums reduce
gradually, and the positive one decreases much quickly
than the negative one. Simultaneously, the extremum
points away from the wake core gradually.
1431.5 896.2
690.1
573.2
495.1
428.9
332.5
-363.3
-350.1
-335.0
-324.5
-310.1
-278.3
-176.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Z(%Chord)
PS
3.87.611.4 15.218.9 22.7
SS
30.3
n1=1000 rpm


Figure 10. Radial vorticity contours in the stator wake re-
gion (Numerical results).
From the above analysis, it is obviously that the vor-
ticity extremum point can approximately represents the
axial velocity inflexion, which indicates the unsteady
point in the wake region. The high vorticity extremum
means the smart variation of the axial velocity in the
wake region. From the variation of the vorticity extre-
mum, it can be found that the distance between the ve-
locity inflexion and wake-core increases gradually along
the axial direction, on both sides of the wake-core. And
the axial velocity on the wake pressure side changes
much more acutely compared to the suction side, that is
to say, the wake pressure side is more unsteady than the
suction side. Along the axial direction, this difference,
between the pressure and suction side, becomes more
and more inconspicuous, because of the influence of the
mixing of the main flow and wake. This variation order-
liness is consistent to the experiment results shown in
Figure 8.
4.2. Wake Variability Relating to Operation
Condition
In this subsection, numerical results under different op-
eration conditions will be brought ou t, for the purpose to
analyze the wake variability relating to the operation
condition. The variation of the rotating speed and mass
flow directly affects the inlet Mach number and the inci-
dent angle of the stato r blade. So, it is more intuition istic
to summarize the wake variability through analyzing the
influence of the inlet Mach number and the incident an-
gle of the stator blade on the wake-core position.
The Figures 11 and 12 respectively give out the varia-
tion of the stator inlet flow angle under different rotating

X. R. XIANG ET AL.555
InletAngle(Degree)
Percent Span (%)
-80 -70 -60 -50 -40 -30 -20 -10 0
0
10
20
30
40
50
60
70
80
90
100
Flow Angle(1000rpm)
Blade Angle
Flow Angle(2500rpm)
Flow Angle(2000rpm)
Flow Angle(1500rpm)
Figure 11. Variation of the stator inlet flow angle under
different rotating speeds .
Inlet Angle(Degree)
Percent Span (%)
-80 -70 -60 -50 -40 -30 -20 -10 0
0
10
20
30
40
50
60
70
80
90
100
FlowAngle(
)
Blade Angle
FlowAngle(
)
FlowAngle(
)
FlowAngle(
)
Figure 12. Variation of the stator inlet flow angle under
different throttle angles.
speeds and mass flow conditions. The stator blade angle
is shown in the both figures (the dash-dot line), so it is
convenient to analyze the changes of the incident angle.
Just as shown in Figure 11, above the 20% span-wise
section, the incident angle decreases gradually along
with the rotating speed increase, while it increase gradu-
ally below this section . Above the 15% span-wise section,
the incident angle increases gradually along with the
mass flow decrease, while it decrease below this section,
just except for the throttle angle α4.
Just as shown in the Figure 13, the stator inlet Mach
number decreases as the rotating speed reducing. The
decrement almost obtains the maximum at the middle
Mach Number
Percent Span (%)
00.01 0.02 0.03 0.040.05 0.060.07 0.08
0
10
20
30
40
50
60
70
80
90
100
1000rpm
2500rpm
2000rpm
1500rpm






Figure 13. Variation of the stator inlet Mach number under
different operation conditions.
span-wise section, and it is nearly symmetrical to the
middle section. As the mass flow reducing, the inlet
Mach number decreases gradually below the 90%
span-wise section, while it appears increase above this
section.
In this part, we will pay attention to the variation of
the wake-core position under different operation condi-
tions, just as shown in the Figure 14. For the Wake-core
Yaw Angles of the axial and tangential velocity are al-
most the same, the analysis is carried out just about the
axial velocity wake-core in this part.
At 15% and 20% span-wise section, the incident angle
is nearly unchanged, but the inlet Mach number de-
creases gradually, respectively as the mass flow and the
rotating speed decreasing. At the 20% section, the
wake-core position which nearby the stator trail edge is
nearly unchanged, but the Wake-core Yaw Angle in-
creases gradually as the rotatin g speed decreasing. Along
with the mass flow decrease at the 15% section, the
Wake-core Yaw Angle is nearly unchanged. Until the
mass flow decreases to a certain value, the Wake-core
Line moves up in the tangen tial direction . That is to say,
the inlet Mach number is an influence factor of the
wake-core position.
At 90% span-wise section, as the mass flow decreas-
ing, the inlet Mach number is nearly unchanged, but the
incident angle increases gradually. Exceptionally for the
throttle angle α4, the incident angle appears decrease
comparing to the α3 situation. At this section, the
Wake-core Yaw Angle increases gradually along the
axial direction, and the Wake-core Line moves up in the
tangential direction. Especially for the α4 situation, the
Wake-core Line moves down in the tangential direction,
for the incident angle decreass compare to α3. That is to
e

X. R. XIANG ET AL. 556
Z (%Chord)
Tangential Position (Degree)
246810 12 14 16 18 20 22 24
13
14
15
16
17
18
19
20
21
22
23
24
1000rpm
2500rpm
2000rpm
1500rpm






(15% )
(20% )
(20% )
(20% )
(20% )
(15% )
(15% )
Z(%Chord)
Tangential Position (Degree)
26 10 14 18 22 26 30 34
13
14
15
16
17
18
19
20
21
22
23
24








(a) (b)
Z (%Chord)
Tangential Position (Degree)
26 10 14 18 22 26 30 34
13
14
15
16
17
18
19
20
21
22
23
24
2500rpm
2000rpm
1500rpm


1000rpm




(
)
Z (%Chord)
Tangential Position (Degree)
246810 12 14 16 18 20 22 24
13
14
15
16
17
18
19
20
21
22
23
24
1000rpm
2500rpm
2000rpm
1500rpm




(
)
(c) (d)
Figure 14. Variation of wake-core position and velocity under different operation conditions. (a) At 15% and 20% span-wise
section; (b) At 90% span-wise section; (c) At 50% span-wise section; (d) At 10% span-wise section.
say, the incident angle is another influence factor of the
wake-core position, and its influence is opposite to the
inlet Mach number.
At 50% span-wise section, as the rotating speed and
mass flow decreasing, the inlet Mach number decreases
and the incident angle increases gradually. At this section,
the variation of the Wake-core Yaw Angle is similar to
the 20% span-wise section, but the increment is much
huger than it. However, at 10% span-wise section, the
variation of the incident angle is opposite to the 50%
section along with the rotating speed and mass flow de-
crease. At this section, the increment of the Wake-core
Yaw Angle is quite smaller than the 50% section, and
also smaller than the 20% section. There is a special
situation, at the 50% section, when the throttle angle in-
creases from α3 to α4, the increment of the incident ang le
is smaller than α2 to α3, but the wake-core moves up in a
huge quantum. This situation can be considered as the
flow separation on the suction side.
5. Conclusions
Based on the analysis of the time-averaged velocity, the
radial vorticity along the axial direction, and the
wake-core development under different operation condi-
tions, the following conclusions were drawn:
1) The experimental and numerical results almost

X. R. XIANG ET AL.557
show the same variation orderliness, the test values are a
little bigger than the numerical results.
2) Along the axial direction, the wake-core moves to
the wake suction side gradually, and the Wake-core Line
of the axial velocity is below the tangential one. The
wake width increases gradually along with wake depth
decreasing, and the decrement of the wake depth reduces
by degrees.
3) The distance between the axial velocity inflexion
and the wake-core increases gradually along the axial
direction. The axial velocity on the wake pressure side
changes more acutely compared to the suction side, and
this different reduces by degrees along the axial direc-
tion.
4) The inlet Mach number and the incident angle are
both the key influence factors of the wake-core position.
As the inlet Mach number decreasing and the incident
angle increasing, the Wake-core Yaw Angle increases
gradually. The wake-core nearby the trail edge is nearly
unchanged, until the inlet Mach number (the incident
angle) reduces (increases) to a certain value.
6. References
[1] D. Gurak, Mehmet S. Kavsaoglu and I. S. Akmandor,
“Multi Block Unsteady Navier Stokes Solution of Com-
pressor Stator in Rotor Wake,” 43rd American Institute of
Aeronautics and Astronautics (AIAA) aerospace sciences
meeting and exhibit, Reno, Nevada, 10-13 January 2005，
p. 1011.
[2] Albert J. Sanders and Fleeter Sanford, “Rotor Blade-to-
Blade Wake Variability and Effect on Downstream Vane
Response,” Journal of propulsion and power, 2002, Vol.
18, No.2, pp. 456-464.
[3] G. M. Mcnerney, C. P. Van Dam and D. T. Yen Nakafuji,
“Blade-Wake Interaction Noise for Turbines with Down-
Wind Rotors,” Journal of solar energy engineering, Vol.
125, No. 4, 2003, pp. 497-505.
[4] M. Roger, “Analytical Modelling of Wake-Interaction
Noise in Centrifugal Compressors with Vaned Diffusers,”
10th AIAA/CEAS Aeroacoustics Conference, Manchester,
10-12 May 2004, p. 2994.
[5] A. Ferrecchia, W. N. Dawes and P. C. Dhanasekaran,
“Compressor Rotor Wakes and Tone Noise Study,” 9th
AIAA/CEAS Aeroacoustics Conference and Exhibit, Hil-
ton Head, South Carolina, 12-14 May 2003, p. 3328.
[6] Shaobin Li, Fu Chen and Peigang Yan, “Numerical In-
vestigation of the Effect of Stator Clocking on Blade
Boundary Layer Flow in Compressor,” Acta Aeronautica
Et Astronautica Sinica, Vol. 28, No. z1, 2007, pp. s62-69.
[7] J. Estevadeordal, S. Gogineni and L. Goss, “DPIV Study
of Wake-rotor Synchronization in a Transonic Compres-
sor,” 31st AIAA Fluid Dynamics Conference and Exhibit,
Anaheim, CA, 11-14 June 2001, p. 3095.
[8] Bo Liu, Zhipeng Cao and Yuanhu Cai, “Numerical
Simulation of Unsteady Vortex in the Wake of Cascade
Flow,” Journal of Northwestern Polytechnical University,
Vol. 23, No. 5, 2005, pp. 562-566.
[9] Guanghua Wang, Baojie Liu and Tao Liu, “A PIV Study
of Near Wake Flow of airfoil Part I-Kinematic Charac-
teristics,” Journal of Aerospace Power, Vol. 14, No. 2,
1999, pp. 119- 124.
[10] Nicole L. Key, Patrick B. Lawless and Sanford Fleeter,
“Rotor Wake Variability in a Multistage Compressor,”
45th AIAA Aerospace Sciences Meeting and Exhibit,
Reno, Nevada, 8-11 January 2007, p. 19.
[11] S. T. Hsu and A. M. Wo, “Near-Wake Measurement in a
Rotor/Stator Axial Compressor Using Slanted Hot-Wire
Technique,” Experiments in Fluids, Vol. 23, No. 5, 1997,
pp. 441-444.
[12] A. Jameson, W. Schmit and E. Turkel, “Numerical Solu-
tion of the Euler Equations by Finite Volume Methods
Using Runge-Kutta Time-Stepping Schemes,” 14th AIAA
Fluid and Plasma Dynamics Conference, Palo Alto, CA,
23-25 June 1981, p. 1259.