Re. Montgomery et B. Dubus, AN ANALYTICAL EVALUATION OF TURBULENCE-INDUCED FLEXURAL NOISE IN PLANAR ARRAYS OF EXTENDED SENSORS, The Journal of the Acoustical Society of America, 94(3), 1993, pp. 1688-1699
Large-area, hull-mounted conformal sonar arrays typically employ exten
ded sensors that are configured to detect acoustic signals by means of
thickness strains that are induced by the incident pressure field. In
most cases, extended sensors also have an appreciable sensitivity to
strains in the lateral dimensions. Thus flexure of such a sensor would
induce a signal that would not be differentiated from that of a targe
t. Hull-mounted conformal arrays are evolving toward using lightweight
, flexible sensors and support structures; therefore, flexure-induced
noise is an ever present concern. This paper presents an analytical ap
proach and a general mathematical model for the noise arising from fle
xure of the array support plate coupled into the array via the lateral
sensitivity of the sensor. The excitation that drives the flexure is
assumed to be the turbulent boundary layer created by motion of the pl
atform through the external fluid medium. An analytical expression is
derived for the equivalent plane-wave spectral density for this noise
source. The result is expressed in terms of the frequency response fun
ction of the plate, the wave-number-frequency spectral density of the
excitation, and the spatial filtering characteristics of the array. An
application is discussed to show that predictions can be obtained in
closed form.