### ASA 126th Meeting Denver 1993 October 4-8

## 5aSA10. Wave vector measurements of empirical design transfer functions.

**Joseph A. Clark
Michael A. Sartori
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*Carderock Div., Naval Surface Warfare Ctr., Bethesda, MD 20084-5000
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Empirical design transfer functions can be used to predict the radiated
noise generated from various components in a system. The Darby method is one
example of an approach used to find these empirical design transfer functions.
For an immersed and radiating structure, near-field measurements of the
pressure field can be wave vector filtered to find the empirical design
transfer function from the structural input point to the acoustic far field.
Assuming a cylindrical body excited by a force and radiating, a discrete line
array of pressure sensing devices are used to measure the near-field pressure.
The acoustic pressure data measured at each point are sampled, digitized, time
averaged, and frequency transformed. The position-frequency domain pressure is
then transformed into the wave vector domain, and the far-field radiation is
predicted. The empirical design transfer function is found by dividing the
predicted far-field radiation by the input force. The mathematical development
of this approach is presented. Simulations are presented for various radiation
sources, including a monopole and a discrete line source. The pressure
predictions of the wave vector are compared with the pressure directly computed
for the sources. [Work supported by ONR.]