Active control of flow-induced noise transmitted through aircraft sidewalls

Description/Abstract

In this paper, the theory and the results are presented of a study concerned with the active control of sound transmitted through aircraft sidewalls when excited by a Turbulent Boundary Layer. The motivation for this study is the control within an aircraft cabin of the flow-induced noise due to wall–pressure fluctuations over the fuselage. First, a theoretical model accounting for the effect of elastic stiffeners is obtained to calculate the boundary layer noise transmitted through tensioned aircraft sidewalls. Parametric studies including comparisons between different models of aircraft fuselage panels valid over different frequency ranges are analyzed. Second, the best possible noise levels reduction that can be achieved are determined using idealized feedback control of the boundary layer noise transmitted through tensioned and stiffened double-panel partitions. It is shown that it is the strategy based on the active suppression of the skin panel structural modes that is the most efficient in terms of the broadband attenuation of the total sound power inwardly radiated. However, it may be more feasible to control the vibration of the trim panel or the pressure in the cavity, and the simulations suggest that the inwardly radiated sound power can still be reduced by a significant amount.