Active control of a fluid-loaded cylindrical shell - part 2: active modal control

Abstract

In part 1, it was shown that the radiated sound pressure due to low frequency vibration of a fluid¬ loaded pressure hull is contributed to by the axial displacement (radiated pressure due to the end plates), and the radial displacement (radiated pressure due to the curved hull surface) [1]. Active control is a technique that can be used to control the hull vibration modes of a submarine and thereby reduce the radiated noise signature due to these modes. In this paper, the effect on the radiated sound pressure resulting from actively controlling the axial and radial displacements for the first two axial resonance modes of a submerged cylinder is investigated. Results show that attenuation of the axial displacement is more effective in reducing the radiated noise compared with attenuation of the radial motion. The control performance is strongly dependent on error sensor location for a given resonance mode. The use of active modal control has shown great potential to control full size hull vibration modes