### ASA 124th Meeting New Orleans 1992 October

## 5aSA6. The spatial and temporal response of fluid-loaded, line-driven
panel structures.

**T. J. Wahl
**

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J. S. Bolton
**

**
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*Ray W. Herrick Labs., School of Mech. Eng., Purdue Univ., West Lafayette,
IN 47907
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*
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In this paper wave propagation is considered in and near fluid-loaded,
line-driven panel structures in several configurations. In one configuration,
for example, the driven panel is separated from a second panel by a
finite-depth, fluid-filled space. In a second case, wave propagation in
fluid-loaded, ribbed panels is considered. In both those cases, solutions for
the spatial and temporal distributions of the panel velocity as well as the
acoustic particle velocity and sound pressure in the adjacent fluid can be
obtained by using wave-number transform techniques. The inversion integral that
defines the spatial response in the frequency domain may then be evaluated by
using the fast Fourier transform algorithm. Subsequently, the temporal response
may be obtained by performing an additional inverse Fourier transform. Having
obtained the pressure and velocity solutions it is a straightforward matter to
compute both the instantaneous and time-averaged intensity in the fluid
adjacent to the structure. By examining the latter quantities the flow of
acoustic energy from the radiating structure to the fluid and vice versa may
easily be visualized. Examples will be given in which energy is shared between
the driven panel and a number of different modes in the adjacent fluid space,
and the existence of multiple coincidence frequencies in that case will be
illustrated. In addition, conversion of subsonic panel wave motion into
radiating components at line discontinuities will be considered.