The Acoustic Characteristics of the RAE 1.5m Wind Tunnel.
ROYAL AIRCRAFT ESTABLISHMENT FARNBOROUGH (ENGLAND)
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Extensive modifications to the old 5ft tunnel at RAE have provided an acoustic tunnel capable of airspeeds up to 60 ms. The drive-fan has been replaced by a seven-bladed unit which is now mounted in the return circuit and acoustic splitters have been installed in the circuit on both sides of the fan. An anechoic chamber lined with polyether foam has been built around the test-section to give good acoustic properties at frequencies above 1 kHz. The tunnel background noise level has been reduced by more than 15 dB for frequencies below 5 kHz with less benefit at higher frequencies. Inside the airstream at 50 ms the noise level for third-octave bandwidths now drops from 75 dB at 1 kHz to 70 dB at 20 kHz. The noise level outside the airstream is some 5-10 dB quieter. Author
- Test Facilities, Equipment and Methods