Transient Sound Field Excited By Cylindrical Shell Transducer In Shallow Ocean

Directional sound sources are widely used in underwater acoustic engineering, for example, cylindrical transducers are often used as transmitters in underwater acoustic communication devices. Thus, it is necessary to investigate the transient sound field excited by underwater directional sources. However, the research with respect to the sound field excited by underwater acoustic sources has mainly focused on that by omnidirectional ones. The studies on the transient sound field excited by directional acoustic sources are relatively scarce. This study will focus on the transient sound field excited by cylindrical shell transducers in shallow ocean.It is difficult to derive the potential function corresponding to common underwater acoustic sources. Thus, the transient vector displacement wave equation instead of the transient pressure wave equation is used to investigate the transient sound field excited by directional cylindrical shell transducer in shallow water. Firstly, the dispersion equation of harmonic waves in a homogenous shallow ocean is derived, and the dispersion characteristics of guided waves in shallow water with different depth are discussed on the basis of numerical results. Secondly, the analytical solution corresponding to the transient sound field excited by cylindrical shell transducers in a homogenous shallow ocean is derived using the eigenfunction expansion method (Normal mode method). The transient pressure amplitude distribution with respect to range and depth is computed and discussed, as well as the transient radial displacement, transient axial displacement and transient pressure distribution with respect to time. Finally, the dispersion equation of harmonic waves in multi-layer shallow ocean is derived and solved. Moreover, the analytical solution of the transient waves excited by cylindrical shell transducers in a multi-layer shallow ocean is derived.The main innovation of this study is solving the transient vector displacement wave equation by the eigenfunction expansion method (EEM). The explicit and concise analytical solution of the transient sound field excited by cylindrical shell transducers is derived. This study has theoretical reference values for the practical underwater acoustic engineering, for example, underwater acoustic communication.