A Low Frequency Minisize Class Ⅵ Flextensional Transducer

The frequencies of the underwater Acoustic equipments are becoming lower and lower.And the demand of underwater acoustic equipments for low frequency sound source is alsobecoming more and more urgent. When the low frequency sound sources were used on theplatforms, the requirements for the volume and weight of sound sources were usually verystrict. So the design technologies for the small size transmission transducers which could beused under very low frequency were one of the hotspots in current transducer research field.The design and manufacture of a novel class Ⅵ small-sized flextensional transducer wasstudied in this paper, and several corresponding minisize class Ⅵ flextensional transducerswere successfully produced. On the other hand, the minisize class Ⅵ flextensionaltransducers were used for the design of MPS (Modular projector System). By these methodswe constructed a new sound source which could be operated under more low frequency.During the research and development of small-sized low frequency transducer, athorough investigation was carried out in the field of the technologies for the low frequencytransmission transducers. Then the class Ⅵ flextensional transducer became the researchobject of this paper. Within the design of this novel transducer, we make full use of thoseadvanced design ideas which were successfully used in the current popular Cymbalflextensional transducer. The structure of the conventional class Ⅵ flextensional transducerwas improved. A novel parametrical model for class Ⅵ flextensional shells with non-equalthickness was established during the study, and almost any kinds of class Ⅵ flextensionalshells can be achieved by adjusting the parameters of the model. The invention of theparametrical model brought great convenience for the design and optimization of this type oftransducer. In the aspect of the designing of the driving source of the transducer, we used PZTring with Inactive Segments substituted for pure PZT ring, which effectively overcame thelimitations of the size of PZT elements used in the class Ⅵ flextensional transducer. Withthis development, not only the performance of the transducer was significantly improved, butalso the design and manufacturing of the transducer become more convenient. Themanufacture technology of this novel minisize class Ⅵ transducer is studied, and several transducer unit samples were produced. Each transducer unit is100mm in diameter, less than35mm in thickness, no more than1kg in weight. The test of acoustic performance wasconducted, the working frequency of the transducer unit was about3.5kHz, and the TVL wasaround124dB. When the transmitting voltage was900V, the source level of the transducerunit would exceed181dB. The hydraulic test for transducer unit has been carried out, TheTransducer unit successfully survived under10MPa hydraulic test without any damage, whichexhibited its excellent deep-water adaptability. All these work shows that the research ondesign and manufacture of this novel minisize class Ⅵ flextensional transducer was ofsuccessfully.In the research of MPS low frequency projector, we refer to the ‘Modular ProjectorSystem’ invention from Canada Ultra Electronics Company.4minisize class Ⅵflextensional transducer units were selected out to form the MPS. They were arranged withvery narrow gap, and by the interaction affections between the transducers, the4transducerschanged into one new sound source. Thus the work frequency of this new transducer wasobviously lower than that of the each unit’s. When the gap between each two transducers was0.8mm, the working frequency of the MPS transducer with4elements is reduced to below2kHz, much lower than the working frequency of the transducer unit. When the4units MPStransducer was applied with565V voltage at1700Hz, the source level would exceeded181dB.Studies involved in this paper showed that, the Modular Projector System technology isan effective and flexible method for constructing small size low frequency sound source. Thenovel minisize class Ⅵ transducer designed and produced in this paper has many advantages,such as small in volume, light in weight, beautiful low frequency acoustic properties andexcellent pressure resistant properties. prominently, it is suitable for being used for theconstruction of the Modular Projector System. By this means, powerful acoustic source withlower operating frequency might easily be achieved.