acoustic testing at wind tunnel facilities of german-dutch ...€¦ · acoustic testing at wind...
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Christophe Hermans, Deputy Director [email protected] (+31.527.248523)
Acoustic testing at wind tunnel facilities of German-Dutch Wind Tunnels (DNW)
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Contents
DNW organization Sites & facilities Customers
DNW Large Low speed Facility LLF Initial design Acoustic upgrades
Key test capabilities & measurement techniques Measurement techniques Test capabilities
Conclusions
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DNW sites
1 2
3 4
5
1) Amsterdam The Netherlands
2) Marknesse The Netherlands
3) Braunschweig Germany
4) Göttingen Germany
5) Köln Germany
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DNW wind tunnel facilities
... and supersonic wind tunnels
Subsonic, ...
transonic ...
Testing for industrial customers: LLF & HST Non-aeronautical tests: LST DLR R&D wind tunnel tests: NWB, KKK, TWG, HDG,
KRG, RWG
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Global customer base
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Contents
DNW organization Sites & facilities Customers
DNW Large Low speed Facility LLF Initial design Acoustic upgrades
Key test capabilities & measurement techniques Measurement techniques Test capabilities
Conclusions
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DNW-LLF original background noise level design target
Early 70ties initial background noise design point based on Fokker F-28 Mk 1000 (take-off side-line noise level at 500 ft)
Aim for 95 EPNdB to account for future more stringent A/C noise requirements
DNW-LLF design phase target set to 73 dB (1/3 octave band @ 1kHz, 80 m/s, 15 m tunnel side line)
Source: Smith, Aircraft noise, Cambridge (1989)
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Acoustic upgrade of LLF
Reduction of background noise: 2010: Modification of Nozzle and Collector (minor noise
sources) 2011: Acoustic lining of turning corners 2 & 3 (up to 6
dB reduction) 2014: Upgrade of Heat Exchanger – Flow Straightener
(analysis ongoing…)
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Contents
DNW organization Sites & facilities Customers
DNW Large Low speed Facility LLF Initial design Acoustic upgrades
Key test capabilities & measurement techniques Measurement techniques Test capabilities
Conclusions
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Acoustic measurement techniques @ DNW
Traversing mechanism (60 GRAS ½” free-field condenser microphone, type 40AC)
160 Far field microphones installed on walls, floor & ceiling (LinearX M51 type)
2 Out-of-flow acoustic microphone arrays (4*4m, 142 M51 free-field microphones each)
2 Wall installed acoustic arrays (1*1m) 5+4 GBM Viper systems (48 channel)
data acquisition systems
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Typical aircraft noise testing setup in OTS
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External noise: acoustic testing
Anechoic lining for reflection absorption Out-of-flow microphone traversing system Acoustic array
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Open rotor (noise) testing
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Full-scale A340 main landing gear
Fly-over-line-view array
Sideline-view array
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0
12 dB
0
level flight
descent
climb
Microphone array
Inflow Wing
Helicopter model with main- & tail rotor
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gear box noise
Wind turbine in DNW-LLF Noise sources identification
in rotor plane
Noise sources identification for individual rotor blades
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0.5x0.5 m2 Wall Array
Wall array and A340 1:10 model
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Various
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Contents
DNW organization Sites & facilities Customers
DNW Large Low speed Facility LLF Initial design Acoustic upgrades
Key test capabilities & measurement techniques Measurement techniques Test capabilities
Conclusions
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Conclusions
DNW facilities are used extensively for aircraft testing by European and non-EU industries
Versatile technologies as part of wind tunnel infrastructure, with focus on aircraft noise (engine integration & ground effect)
Additional strength through availability of technology and analysis capabilities from parent institutes DLR and NLR