W.R. Graham

In order to investigate boundary-layer induced noise in aircraft, the excitation of a simply-supported flat plate by a turbulent boundary layer is considered. Initially, the plate is bare, and the well-known modal analysis for a fluid loaded panel applies. This analysis is used to investigate the acoustic power radiated by the plate, and its dependence on the parameters of the problem. It is found that alterations in structural damping, critical frequency and the degree.of structural inhomogeneity affect the radiated power significantly, but that hydrodynamic coincidence effects are relatively unimportant. The model is then extended to include the effects of internal insulation and trim, by covering the plate and baffle surface with representative structuraVacoustic elements. These are found to have an enormous modifying effect on the plate vibration and radiated sound, and a numerical study shows that, while the final three findings for the bare plate remain valid, the structural damping is now of greatly reduced imponance.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.87-96; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1992