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On the Instantaneous Dynamics of the Large-Scale Structures In The Impinging Round Jet
J. W. Hall & D. EwingDepartment of Mechanical Engineering,McMaster University, Hamilton, Ontario, Canada
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Turbulent Round Impinging Jet
Flow visualization of impinging round jet, H/D=2.0, Re=20000,
Popiel and Trass (1991).
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Turbulent Plane Wall Jet
Gogineni and Shih (1997)http://www.eng.fsu.edu/~shih/succeed/flow-vis.htm
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Harvey and Perry’s Rebounding Vortex
Harvey and Perry (1971)
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Three-Dimensionality of Structures?
Tsubokura (2003) Re=2,000 Forced at Strouhal FrequencyFully Developed Pipe FlowH/D = 9
Landreth and Adrian (1991) observed instantaneous flow was not symmetric in PIV measurements
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Investigation of the Three-Dimensionality of Large-Scale Structures
Hall et al (2002)
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Effect of Nozzle-to-Plate Distance
0 1 2 3 40.00
0.05
0.10
0.15
0.20 p/
0.5U
o2
r/D
0
20
40
60
80
100
120
140
160
180
H/D=2.0 H/D=3.0 H/D=4.0 H/D=6.0
Nu
Jet Exiting a Long Pipe
Re=23,000
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Pressure Spectra
10 100 10001E-4
1E-3
0.01
0.1 r/D=1.0 r/D=1.5 r/D=2.0 r/D=2.5
H/D=4.0
Fpp
(r1,
r2=
r 1, =
0,
f) {
Pa2 /H
z}
f (Hz)10 100 1000
1E-4
1E-3
0.01
0.1 H/D=3.0 r/D=1.0 r/D=1.5 r/D=2.0 r/D=2.5
Fpp
(r1,
r2=
r 1, =
0, f)
{P
a2 /Hz}
f (Hz)
10 100 10001E-4
1E-3
0.01
0.1 H/D=2.0 r/D=1.0 r/D=1.5 r/D=2.0 r/D=2.5
Fpp
(r1,
r2=
r 1, =
0, f)
{P
a2 /Hz}
f (Hz)
r/D=1.0
r/D=1.5
r/D=2.0
r/D=2.5
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Azimuthal Spectra
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0H/D=2.0
Bpp
(r1,
r2=
r 1, m
, =
0)
(P
a2 )
Mode Number
r1=1.0D
r1=1.5D
r1=2.0D
r1=2.5D
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
H/D=3.0
Bpp
(r1,
r2=
r 1, m
, =
0)
(P
a2 )
Mode Number
r1=1.0D
r1=1.5D
r1=2.0D
r1=2.5D
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
H/D=4.0
Bp
p(r 1,
r2=
r 1, m
, =
0)
(P
a2 )
Mode Number
r1=1.0D
r1=1.5D
r1=2.0D
r1=2.5D
r/D=1.0
r/D=1.5
r/D=2.0
r/D=2.5
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Azimuthal Frequency Spectra, H/D=2.0
101
102
103
10-4
10-3
10-2
10-1
f (Hz)F
pp(r
1,r
2=
r 1,m
,f)
(Pa2
/Hz)
All modesm=0m=1m=5
~10
110
210
3
10-4
10-3
10-2
10-1
f (Hz)
Fp
p(r
1,r
2=
r 1,m
,f)
(Pa2
/Hz)
all modesm=0m=1m=5
~
r/D=1.0 r/D=1.5
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Two-Point, Two Time Correlations
H/D=2.0
H/D=4.0
r1/D =1.0
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Dynamics of the Instantaneous Structures Pressure sampled at 800Hz for 350 blocks of 400 data points ESP scanner system at Boundary
Layer Wind Tunnel, University of Western Ontario
Signals are phase corrected in post-processing
Perform Proper Orthogonal Decomposition in Azimuthal Direction Fourier Modes
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Pressure Field, H/D=2.0
Mean Pressure Fluctuating Pressure
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Comparison to microphone data
Hall et al. (2003)
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Pressure Spectra
m=0 m=0
All modes
All modes
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H/D=2.0
All modes
m=0,+/-1
m=0
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H/D=4.0
m=0,+/-1
All modes
m=0
m=0 to +/-5
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Impinging Jet DNS
Tsubokura (2003)Re=2, 000
Forced at Strouhal FrequencyH/D = 9
Satake and Kunugi (1998)Re=10000
H/D = 6, Confined
Inlet Condition Fully Developed Pipe Flow
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Wavelet Analysis: Instantaneous Pressure
r/D=2.0
r/D=1.0
r/D=1.5
H/D=2
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Wavelet Analysis: Azimuthal Modes
All modes
m=0
m=1
m=5
H/D =2, r/D =1.5
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Wavelet Coefficients: Mode 0
r/D=2.0
r/D=1.0
r/D=1.5
H/D=2
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Wavelet Coefficients: Mode 1
r/D=2.0
r/D=1.0
r/D=1.5
H/D=2
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Azimuthal Mode 1: Precessing?
r/D=1.0
r/D=1.5
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Wavelet Analysis: Effect of H/D
H/D =2, r/D =1.5
All modes
m=0
m=1
m=5
H/D =4, r/D =1.5
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Wavelet Analysis: Effect of H/D
r/D=1.0
r/D=1.5
H/D=2.0 H/D=4.0
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Concluding Remarks Measurements of the instantaneous wall pressure fluctuations were used to
examine the development of the large-scale structures in the near field of the radial wall jet.
The inclusion of at least azimuthal mode 1 was necessary to reasonable model the dynamics of the flow.
Contributions from azimuthal mode 0 and 1 underwent variations in magnitude that persisted over periods corresponding to the passage of several structures.
There were extended periods where the slope of the phase of mode 1 was linear suggesting there may be periods of jet precessing of varying duration and direction.
Structures contributing to fluctuating wall pressure did not appear to become significantly more intermittent as H/D increased.
There was less systematic variation of the phase of mode 1 as H/D increased suggesting less systematic jet precessing.
