DUCT AEROACOUSTICS

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DUCT AEROACOUSTICS from Technological
Applications to the Flute
Sylvie Dequand Supervisors A. Hirschberg
Y. Aurégan
Technische Universiteit Eindhoven
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DUCT AEROACOUSTICS
DUCT AEROACOUSTICS
DUCT AEROACOUSTICS
ACOUSTICS ? science of sound
small pressure wave example of source loudspeaker
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from Technological Applications to the Flute
The cross-junction ? Acoustical measurements ?
Flow visualization ? Simple analytical model ?
Numerical simulations
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from Technological Applications to the Flute
p(t)
Acoustical pressure p at the resonance frequency
f c0 / 4L
closed side branch
L l /4
p
U0
? no radiation in the main pipe ?
acoustically closed system at the resonance
frequency ? good testcase of the Euler code
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from Technological Applications to the Flute
1st hydrodynamic mode (p1)
Acoustic modes
2nd hydrodynamic mode (p2)
p1
p2
n 3
L
n 2
n 1
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from Technological Applications to the Flute
Numerical simulations
Flow visualization by Peters (1993)
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from Technological Applications to the Flute
1.5
pulsation amplitude u/U0 at the junction
Euler simulations
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measurements
0.5
p(t)
0
L
U0
-0.5
-1
0.5
1
1.5
2
2.5
3
0
time t/T
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from Technological Applications to the Flute
The sunroof of a car
Flow (U?0)
Renault Avantime European project Flodac
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from Technological Applications to the Flute
Helmholtz resonator
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from Technological Applications to the Flute
Helmholtz resonator effect of the inner edge
Pulsation Amplitude in the neck
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from Technological Applications to the Flute
Helmholtz resonator effect of the downstream edge
Pulsation Amplitude in the neck
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from Technological Applications to the Flute
Helmholtz resonator effect of the downstream edge
Pulsation Amplitude in the neck
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from Technological Applications to the Flute
Helmholtz resonator
vortex path
numerical simulations
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Helmholtz resonator
can be removed
flow
fixed
W
opening
H
cavity
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from Technological Applications to the Flute
Our flute
can be removed
flue channel
60o-labium
fixed
W
jet flow
mouth
cavity
H
the transverse flute
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from Technological Applications to the Flute
Our flute
15o-labium
flue channel
W
jet flow
mouth
cavity
H
the recorder