Vibroacoustics of Flow-Excited Structures
Excitation of structures by flows and resulting vibration and radiated noise is a problem of practical interest in various fields; as example of applications one can cite the prediction and reduction of cabin noise in aircrafts, sound in sonar domes in underwater acoustics, and vibration and noise generated in pipes. The study of this flow-structure interaction is a complicated subject as it adds the difficulties of fluid dynamics (the excitation field, which is usually random in space and time) to those of structural vibrations.
This chapter is divided in three main sections. The first section presents an overview on fluid mechanics of turbulent flows with a physical introduction and some discussion on the techniques in use to solve the equations of turbulent motion. The second one focuses on the description of turbulent boundary layers and more specifically on the induced wall-pressure field which acts as a distributed random excitation field on structures. The third section considers the vibroacoustics response of a simple structure (thin rectangular flat plate simply supported along its entire periphery) to wall-pressure fluctuations. The influence of the choice of various models of the wall-pressure field in wavenumber-frequency space is discussed together with experimental and numerical examples.
KeywordsTurbulent Boundary Layer Pressure Fluctuation Convection Velocity Thin Rectangular Plate Pressure Spectrum
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