Minimisation of the sound power radiated by a submarine through optimisation of its resonance changer

An important cause of sound radiation from a submarine in the low frequency range is fluctuating forces at the propeller. The forces are transmitted to the hull via the shaft and the fluid. Sound radiation occurs due to hull and propeller vibrations as well as dipole sound radiation caused by the operation of the propeller in a non-uniform wake. In order to minimise sound radiation caused by propeller forces, a hydraulic vibration attenuation device known as a resonance changer can be implemented in the propeller/shafting system. In this work, cost functions that represent the overall radiated sound power are investigated, where the virtual stiffness, damping and mass of the resonance changer were chosen as design parameters. The minima of the cost functions are found by applying gradient based optimisation techniques. The finite element and boundary element methods are used to model the structure and the fluid, respectively. The adjoint operator is employed to calculate the sensitivity of the cost function to the design parameters. The influence of sound radiation due to propeller vibration on the optimisation of the resonance changer as well as the influence of the reduction in amplitude for higher harmonics of the blade-passing frequency on the control performance is investigated.

[1]  Krister Svanberg,et al.  A Class of Globally Convergent Optimization Methods Based on Conservative Convex Separable Approximations , 2002, SIAM J. Optim..

[2]  Faker Ben Belgacem,et al.  The Mortar finite element method with Lagrange multipliers , 1999, Numerische Mathematik.

[3]  Nicole Kessissoglou,et al.  Optimisation of a resonance changer to minimise the vibration transmission in marine vessels , 2007 .

[4]  George J. Davis,et al.  Adaptive Quadrature on a Message-Passing Multiprocessor , 1992, J. Parallel Distributed Comput..

[5]  Nicole Kessissoglou,et al.  Structural and acoustic responses of a submarine hull due to propeller forces , 2009 .

[6]  S. Marburg.  Developments in structural-acoustic optimization for passive noise control , 2002 .

[7]  Nigel Peake,et al.  Acoustic excitation of hull surfaces by propeller sources , 2004 .

[8]  R. D. Ciskowski,et al.  Boundary element methods in acoustics , 1991 .

[9]  R. Haftka,et al.  Elements of Structural Optimization , 1984 .

[10]  David T. Wilton,et al.  Coupled Boundary and Finite Element Methods for the Solution of the Dynamic Fluid-Structure Interaction Problem , 1992 .

[11]  Jorge Nocedal,et al.  A Limited Memory Algorithm for Bound Constrained Optimization , 1995, SIAM J. Sci. Comput..

[12]  K. Svanberg.  The method of moving asymptotes—a new method for structural optimization , 1987 .

[13]  Donald Roe Ross,et al.  Mechanics of underwater noise , 1976 .

[14]  Jill Carlton,et al.  Marine Propellers and Propulsion , 2007 .

[15]  T. Mellow,et al.  On the sound field of an oscillating disk in a finite open and closed circular baffle , 2005 .

[16]  J. Z. Zhu,et al.  The finite element method , 1977 .