Development of radiation mode shapes for cylindrical shells

Abstract

For many acoustical applications, it is desirable to evaluate the radiated power. About two decades ago, a set of formulations were developed to represent the acoustic radiation in terms of radiation mode shapes. A convenient method for determining these radiation modes involves representing the radiating structure as a set of elementary simple radiators, from which the radiation can be decomposed into the set of orthogonal radiation modes. Radiation mode shapes are very useful not only for calculating the power, but also to determine which modes are the most efficient radiators. This generally allows one to achieve a rather accurate estimate of the radiated power by including only a relatively small number of the most efficient radiating modes. This concept has significant implications for an efficient strategy for implementing an active noise control system. Previous work reported in the literature has primarily focused on evaluating the radiation mode shapes of flat structures, such as beams and plates. There has not been as much reported on the radiation mode shapes for cylindrical shells. This paper focuses on implementing these concepts to determine the radiation mode shapes of cylindrical shells and using them to determine the radiated acoustic power.