Active control of low-frequency hull-radiated noise

A theoretical analysis of the active control of low-frequency radiated pressure from a finite cylindrical pressure hull is presented. The control action is implemented through a Tee-sectioned circumferential stiffener driven by a pair of PZT stack actuators. The actuators are located under the flange of the stiffener and are driven out of phase to produce a control moment. This paper examines the effects of control actions, both structurally and acoustically, for a control moment applied around the circumference of the hull. The model considered is a water-loaded finite stiffened cylindrical shell with rigid ends caps. One end of the shell is excited by an axial force while the other end is free. Control action is achieved by using the PZT actuators and stiffener to minimize the structural response and radiated pressure. It was found that the control system was capable of reducing by approximately two-thirds of the radiated pressure for the first three axial modes.