EXPLORATORY STUDY TO REDUCE FAN NOISE IN THE TEST SECTION OF THE NASA LANGLEY FULL-SCALE WIND TUNNEL

摘要

This report summarizes the results of work performed by Bolt Beranek and Newman Inc. (BBN) under Contract NAS1-13585 to identify feasible measures to reduce the intensity of the fan noise in the test section of the NASA Langley 30 ft x 60 ft sub?sonic wind tunnel.nFirst, field measurements were performed to document exist?ing aerodynamic and acoustic conditions.The purpose of these experiments was to (1) obtain the "transfer function" between the sound power output of the fan and the sound pressure on the test platform, (2) evaluate the sound attenuation around the tunnel circuit, (3) measure simultaneously the flow profile and the turbulence spectrum of the inflow to the fan and the noise on the test platform, and (4) perform flow observations and listening in various parts of the tunnel to identify secondary noise sources.