Flow excitation of a finite curved elastic shell

Thesis

This dissertation investigates the vibrations and acoustics of a particular type of sonar array, in which the hydrophone array is attached to the hull of the ship and is protected from the external flow by a sonar dome, with a free-flooding space between the dome and the array. When the ship moves through the water, a turbulent boundary layer forms over the sonar dome, and the pressure fluctuations in this cause vibrations of the dome and sound waves in the water between the dome and the array. In some circumstances the array detects these waves as appearing to originate at certain bearings either side of end-fire, degrading the array's performance. It has been suggested that this effect is due to longitudinal wave motion in the sonar dome. To investigate the validity of this claim, and to suggest other possible explanations, various simplified models of the problem are considered, treating the sonar dome as an infinite thick plate, an infinitely long cylindrical shell, and a finite thin plate. Acoustic resonances in the water between the dome and the array are also considered.

Authors: Jones, G

• Publisher: University of Oxford;Mathematical Institute
• Publication date: 2003
• Type of award: DPhil
• Level of award: Doctoral