Noise Measurement
Acoustic measurements are possible in dedicated test sections, available in S1MA (for high speeds), F1 and CEPRA19 (for low speed).
Since June 1999, the S1MA wind tunnel has been equipped with an anechoic test section for acoustic tests at high speeds, up to Mach 0.85. The anechoic lining extends from the contraction through the test section to the diffuser. The actual liner arrangement has been optimised to obtain good attenuation of diffuse field sound waves, in the frequency range between 200 Hz and 20 kHz.
One purpose of these tests is the possiblity to identify the aerodynamic noise sources, by correlating dynamic pressure measurements with microphone signals. Early results show that acoustic reflections from the test section walls are appreciably reduced, when compared with similar tests in an untreated test section.
MAS1 project - An innovative project in wind tunnel testing field...
OBJECTIVES:
Today Onera Large Wind Tunnels are mainly used to qualify, in good simulation conditions, the aerodynamic performances.
It is proposed to develop and implement new methods and techniques, allowing to simultaneously perform acoustic and aerodynamic measurements in test sections not especially design for this purpose and to focus mainly on S1MA and F1.
The leadership is assured by GMT working closely together with DSNA and DMAE specialists (Scientifical department of the acoustic domain at Onera)
MAS1 tasks are planned for a duration of 4 years from 2008 to 2011.
MAS1 tasks:
v Development of methods:
De-noising, de-reverberation, etc.
v Development of instrumentation & Metrology:
Wall and flow field antennas
Cone nose measurements
Directive measurements
Reference acoustic sources, etc.
v Experimental tests : qualification, validation
v Definition and market exploration of a GMT acoustic measurement system
v Testing methods and wind tunnel acoustic improvements
v Training / capability transfer to GMT / Scientific support