Geometry considerations for jet noise shielding with CTOL engine-over-the-wing concept

Abstract

Jet noise shielding benefits for CTOL engine-over-the-wing installations were obtained with various model-scale circular nozzles and wing chord geometries. Chord-to-nozzle diameter ratios were varied from 3 to 20, while ratios of nozzle height above the wing to the diameter were varied from near zero to 3. Spectral noise data were obtained with jet velocities from 640 to 1110 ft/sec. Characteristics of low frequency noise sources are discussed. Jet-noise shielding is correlated in terms of acoustic and geometric parameters. Implications of extending the model-scale data to full-scale are discussed.