Control of Structural Vibrations by Vorticity Production

摘要

Analytical models are investigated of the damping of sound and structuralvibrations by vorticity production in the apertures of bias flow and grazing flow perforated elastic plates. A generalized bending wave equation is formulated for a plate perforated with an homogeneous distribution of small apertures, and is used to predict the attenuation of sound and resonant bending waves. The results depend on the Rayleigh conductivity of an aperture in a thin plate which is determined numerically in the presence of one and two-sided mean grazing flows. The Kutta condition is applied to model the generation of vorticity at the edges of the aperture by an applied time-varying pressure field. The influence of flow nonlinearity in the apertures is investigated by use of a model equation for the aperture flows. Preliminary validation tests are described, and recommendations made for future research.