Turbulent boundary layer noise transmission into an aircraft fuselage—Modeling and analysis

Abstract

The turbulent boundary layer (TBL) pressure fluctuations on the exterior of an aircraft excite the fuselage structure which in turn radiates noise inside the passenger cabin. In most of the previous analytical and experimental studies of sound transmission loss of structures, only acoustic excitation is considered. It is then assumed that the transmission loss of a structure due to the TBL pressure field will be the same as that for the acoustic field. The main objective of this paper is to examine the effects of the TBL pressure field on the transmission loss of a fuselage structure and compare it with the acoustic transmission loss. The vibration and acoustic response of a circular cylindrical shell due to the TBL excitation is first modeled with a finite-element-based computational approach. The finite-element model of the cylindrical shell panel is validated with the results from classical analytical model. The vibration and acoustic response of an aircraft fuselage due to the TBL pressure field is then calculated using the finite-element model. The incident TBL pressure field is simulated by a cross-spectral formulation of the excitation field. The noise reduction characteristics of the fuselage due to acoustic and TBL pressure fields are compared.