An Estimate Of The Noise Shielding On The Fuselage Resulting From Installing A Short Duct Around An Advanced Propeller
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An Estimate of the Noise Shielding on the Fuselage Resulting from Installing a Short Duct Around an Advanced Propeller
Author: National Aeronautics and Space Administration (NASA)
language: en
Publisher: Createspace Independent Publishing Platform
Release Date: 2018-08-16
A simple barrier shielding model was used to estimate the amount of noise shielding on the fuselage that could result from installing a short duct around a wing-mounted advanced propeller. With the propeller located one-third of the duct length from the inlet, estimates for the maximum blade passing tone attenuation varied from 7 dB for a duct 0.25 propeller diameter long to 16.75 dB for a duct 1 diameter long. Attenuations for the higher harmonics would be even larger because of their shorter wavelengths relative to the duct length. These estimates show that the fuselage noise reduction potential of a ducted compared with an unducted propeller is significant. Even more reduction might occur if acoustic attenuation material were installed in the duct. Dittmar, James H. Glenn Research Center NASA-TM-100262, E-3891, NAS 1.15:100262 RTOP 535-03-01...