Use of impedance mismatch in the control of coupled acoustic radiation of the submarine induced by propeller-shaft system

The three-dimensional sono-elasticity method recently developed by Zou et al. [1,2] is employed to model the coupled acoustic radiation of the submarine induced by the propeller-shaft system. Vibration isolators are widely used to control the vibration and acoustic radiation induced by machines. Nevertheless, they are not seen in the control of propeller-shaft-hull coupled vibration and acoustic radiation induced by the propeller-shaft system. The relationship between the stiffness of isolator for shaft and the characteristic frequency of coupled acoustic radiation is clearly identified. The mechanism of how the stiffness of isolator for shaft affects the coupled acoustic radiation is discussed. Furthermore, the influence of the input impedance of the base for thrust bearing upon the coupled acoustic radiation is investigated. A new vertically symmetrical base with high input impedance for thrust bearing is proposed. To realize impedance mismatch, the isolator with low stiffness and the new base for thrust bearing are applied to the propeller shaft-hull system. The coupled acoustic radiation of the submarine induced by the propeller-shaft system is effectively reduced.