Which approach for aero-acoustic problems associated to ... · Which approach for aero-acoustic...
17
INT2012 PAGE 1 Which approach for aero-acoustic problems associated to façade elements? Jean Baptiste Chéné / Pierre Kerdudou / Catherine Guigou-Carter
Transcript of Which approach for aero-acoustic problems associated to ... · Which approach for aero-acoustic...
INT2012 PAGE 1
Which approach for aero-acoustic problems associated to façade
elements?
Jean Baptiste Chéné / Pierre Kerdudou / Catherine Guigou-Carter
Contents
I. Examples – illustration of the problem
II. Physical phenomena
III. Existing approaches
IV. Air-borne and structure-borne sound characterization
INT2012 PAGE 2
IV. Air-borne and structure-borne sound characterization
in the Jules Verne Wind Tunnel (Nantes)
V. Air-borne sound characterization in the Eiffel wind
tunnel (Paris)
VI. Diagnostic monitoring system
VII. Conclusion
Examples
Façade elements
INT2012 PAGE 3
Examples
Urban wind turbine
INT2012 PAGE 4
Physical phenomena
(main one)
o Real aero-acoustic effect:
o Broadband: generated by a sum of small complex turbulence zones
produced by the wind on different parts of building façade elements
o Tonal/whistling:
o well defined structure (tubes, etc …) => organized wakes (Kármán vortex street)
o Cavity => Helmholtz resonator
o Resonance of the façade element:
o Air-borne and/or structure borne noise
o Mechanical/structural origin:
o Air-borne and/or structure borne noise generated by shocks, friction…
due to too flexible element and/or fixed steel on steel …INT2012 PAGE 5
Existing approaches
(Non exhaustive)
o Adaptation of ventilation element test facility
o Using modified ISO 3741
o Using only Lp measurement
o Non aero-acoustic scaled wind tunnel (background
Air-borne
noise
o Non aero-acoustic scaled wind tunnel (background noise problem)
o For building-mounted wind turbines structure-borne noise, Andy Moorhouse gives an approach with an in-situ blocked force approach.
=> No global approach and no test in real one scale aero-acoustic facility was found in the literature
INT2012 PAGE 6
�
�
�
�
High speed
tunnel
Environnemental
tunnel �
Jules Vernes – Wind Tunnel
Description of the facility
o Section ≈ 100m²
o 6 fans (Ø 3m)
o Constant rotation speed: 375 tr/min
²
� �
�
�
�
OPEN
Acoustic treatment
speed: 375 tr/min
o 13 propeller blades with non constant lead
o Fundamental frequency of the fans : 81Hz
o High background noise
INT2012 PAGE 7
Jules Vernes – Wind Tunnel
Description of the approach
o For structure-borne noise, the modified reception plate method (EN 15657-1)
o For air-borne sound: 4 microphones (B&K type 4190 + aerodynamic conical head type UA-0386) in the flow at upstream positions (to avoid turbulences).
INT2012 PAGE 8
Jules Vernes – Wind Tunnel
Some air-borne sound results
Noise pressure level in one
INT2012 PAGE 9
Noise pressure level in one
position, with (blue) and
without (green) sample at
15m/s
Eiffel – Wind Tunnel
Description of the facility
o free feedback
o non guided experimental tunnel (Ø 2 m)
o Wind speed proportional to the fan speed
INT2012 PAGE 10
Eiffel – Wind Tunnel
Description of the approache
o Only air-borne sound measurements
o 4 microphones out of the flow
o Narrowband noise measurementsmeasurements
INT2012 PAGE 11
Eiffel – Wind Tunnel
Few air-borne sound results
o free feedback
o non guided experimental tunnel (Ø 2 m)
o Wind speed o Wind speed proportional to the fan speed
INT2012 PAGE 12
Background noise level in Eiffel wind
tunnel as a function of wind speed
Comparison between measurement with sample
(15m/s and 71% of the engine electric power) and without
sample in two conditions :(1) equal wind speed and (2) equal % of the engine electric power.
High head loss in the air flow
Eiffel – Wind Tunnel
Few air-borne sound results
Lp measurement with and
without a “small” sample
with low global head loss
INT2012 PAGE 13
Diagnostic monitoring system
INT2012 PAGE 14
Conclusion
� Two different approaches of the phenomena have been tested
and discussed in this paper.
� Based on those first experiences, research program will start
INT2012 PAGE 15
� Based on those first experiences, research program will start
in order to improve both theoretical and experimental
approaches.
�A clever (we hope) monitoring system has been already
developed and will be validated by the end of the year.
Future work
� Validation of the “Diagnostic monitoring system” and first in-situ experiment
INT2012 PAGE 16
� Research in the Eiffel wind tunnel (only airborne sound and real aero-acoustic phenomena) in order to have a better understanding of the problem.
Acknowledgments
INTERNOISE 2012 organization comity
INT2012 PAGE 17
Pierre Kerdudou and Catherine Guigou-Carter
