Calculations of the Sound Scattering from Fluid-Filled Spherical Shell Sonar Targets,
DEFENCE SCIENCE AND TECHNOLOGY ORGANIZATION CANBERRA (AUSTRALIA)
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The theory of the sound pressure scattered from a fluid filled spherical shell immersed in a second fluid is developed. An arbitrary combination of fluids may be used to fill the shell, and both the sound source and the receiver may be in the near field. The theory is used to calculate the pressure field in both the interior and exterior fluids and is extended to determine the time dependence of the reflected signal and the target strength. The dependence of these quantities as a function of frequency and pulse type shell material, diameter and wall thickness fluid combination temperature and distance of the receiver from the sphere is examined, and is shown to be sensitive to most of these parameters. The performance of spheres filled with a Freon 113TM - ethanol or Fluorinert FC-72TM - n-hexane mixture is considered.