The Study Of Directional Underwater Acoustic Transducer Based On Multipole Model

Directional transducer is good for reducing reverberation and increasing detection range for active detection.The size of low frequency transducer is much smaller than wave length so that it's usually omni-directional.The study of low frequency directional transducer is significant.An investigation is made of the low frequency directional transducer based on multi-pole sound source.Firstly,a theoretical study was made of multi-pole sound source.Based on point acoustic source,a cardioid beam pattern and a super cardioid beam pattern had been discussed.A quadrupole model was proposed and discussed.Consider the fact that under the mutual radiation,there was an in-depth study of the modal.Secondly,an experiment was made for directional source.According to the theory model of quadrupole source,an experiment model composed of spherical transducers was built.A test which verifies for theoretical study was finished in the anechoic tank.Thirdly,a finite element analysis was developed for quadrupole transducer.Two in-phase source and out of phase source was analyzed by finite element method based on the transducer model.A super cardioid beam pattern and omni-directional beam pattern were embodied based on the transducer model.The results of finite element analysis were discussed.The transmitting voltage response is 132.5 dB when the transducer works under the omni-directional acoustic emission,and it is 143 dB when the transducer works with the super cardioid beam pattern.In general,directional acoustic emission makes for better transmitting voltage response of transducer.Finally,an experiment was developed based on quadrupole transducer in the anechoic tank.The transducer was applied for two in-phase source,two out of phase source and quadrupole directional source.The transmitting voltage response is 143 dB when the transducer works with the super cardioid beam pattern.The experiment results were compared with the results of simulation.