Thirty Years' Progress of Underwater Sound Projectors in China

Progress in the development of underwater sound projectors over the past thirty years in China is presented in this paper. This progress may be divided into four parts: (I) The development of new underwater sound projectors based on new transducer materials such as rare earth giant magnetostrictive materials, relaxation ferroelectric materials and piezoelectric composite materials; (II) The design of new structures and energy transfer mechanisms such as flex-tensional transducers, mosaic cylindrical transducers, longitudinal transducers, flexural disk and beam transducers; (III) The development of new configurations that broaden transducer bandwidth such as free-flooded ring transducers, broadband free-flooded flex-tensional transducers, doubly-excited longitudinal transducers, hybrid longitudinal transducers and matching layer technology; (IV) The development of new transducer design and analysis tools such as finite-element models for complex geometries, structure and fluid coupling mechanisms. These models have been used to optimize the design of a variety of projectors including low-frequency transducers, high power transducers and broadband wide-beam transducers.