Control of Machinery-induced Underwater Radiated Noise from Naval Vessels

Modern naval vessels must satisfy increasingly severe underwater-radiated noise (URN) performance specifications if they are to be employed as ASW or MCM platforms. The designer must achieve the best possible compromise between often-conflicting design requirements for size, mass, isolation, stiffness, clearances, etc. While emerging technologies such as active noise control have great potential, they are not yet a panacea for underwater radiated noise problems, and so the application of passive techniques continues. This paper demonstrates, by reference to recent machinery installations, that proven, reliable, passive techniques can be used to isolate machinery to a very high degree over broad frequency ranges. Performance requirements for active control systems are beginning to emerge clearly in terms of the frequency ranges of interest for particular transmission paths, the degree of cancellation that must be achieved and the magnitude of the residual problem.