NOISE CONTROL FOR AIRCRAFT ENGINE TEST CELLS AND GROUND RUN-UP SUPPRESSORS. VOLUME 3: AN ENGINEERING ANALYSIS OF MEASUREMENT PROCEDURES AND OF DESIGN DATA
BOLT BERANEK AND NEWMAN INC CAMBRIDGE MA
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The physical aspects of noise control in aircraft engine test cells and ground run-up suppressors are reported. The measurement procedures and the noise reduction data that form a technical basis for many of the techniques and ideas presented in the other volumes are analyzed. Errors arising from the measurement equipment, wide band frequency analysis, random variations of noise level in time and space, the use of artificial noise sources, variations in air flow conditions and different measurement procedures are investigated to obtain an objective measure of the reliability of data obtained from an AF sponsored program of acoustical evaluations of test cells and ground run-up suppressors. Data on impervious barriers and noise control components for air passages are analyzed. The performance of a single wall barrier can be reliably estimated, but the large noise reductions expected from double wall barriers are seldom ob tained because of flanking paths. The performance of noise control components for air passages was found to differ significantly from that predicted by theory first order modes, long treatment.
- Noise Pollution and Control