Sound radiation from nested cylindrical shells

ABSTRACT Fluid-loaded nested cylindrical shells are modelled using a doubled-walled cylindrical shell structure closed at each end by circular end plates and excited by a transverse force at one end. The effects of various influencing factors on the radiated sound power are examined corresponding to non-concentricity of the cylindrical shells, entrained fluid and rib connections in the annular space between the inner and outer shells. The doubled-walled cylindrical shell is modelled using two different approaches to consider low and high frequencies. In the first approach, a fully coupled finite element/boundary element model of the fluid-loaded nested cylindrical shells is developed, whereby the finite element method is used to model the structure and the boundary element method is used to model the entire fluid domain. The second approach uses an energy based method to consider the high frequency range. A hybrid finite element/statistical energy analysis technique is developed whereby the rigid components corresponding to the annular ribs and end plates are modelled using finite elements, while the fluid and flexible shell structures are modelled using statistical energy analysis. Results obtained using the deterministic and statistical numerical methods are compared.