Study On External Air Bag Deep Water Moving Coil Projector

With the increasing demand for marine science and technology,countries around the world have invested a large amount of research resources in the field of underwater acoustic technology.As the forefront of underwater acoustic technology,underwater acoustic transducers have naturally become an important field in underwater acoustic research.As a kind of transducer with good performance in low and ultra-low frequency band,moving coil projector is mainly used in underwater acoustic field as acoustic decoy or noise simulation equipment.Due to the special structure of electric transducers,it is often necessary to install pressure compensation airbags to support their normal operation in deep water environments.However,this inevitably brings with it some shortcomings of transducers,such as limited heat dissipation capacity,inappropriate continuous working time,and limited working depth of transducers and poor low-frequency performance in deep water.This paper designs and studies an external airbag type transducer that connects the airbag and radiation surface externally to the exterior of the driving vibrator housing.The interior of the driving vibrator housing is filled with oil,using a liquid environment instead of the traditional gas environment.At the same time,the role of the airbag becomes sound insulation.By covering one side of the radiation surface,the acoustic radiation mode of the external radiation surface is changed to ensure the size of its sound source level.Finally,problems such as limited working depth and short continuous working time of the transducer have been solved to a certain extent.Firstly,the equivalent circuit method is used to analyze the external airbag transducer,and the sound source level frequency response curves of the transducer under different water depths and different initial length of the airbag are obtained through theoretical calculation;Analyze the impact of the two on the performance of the transducer,and compare the performance with traditional electric transducers to analyze the advantages and disadvantages of different structures.Secondly,based on the finite element software COMSOL,the simulation analysis of the external airbag transducer was conducted.After establishing the simulation model of the external airbag transducer,the water depth conditions and the initial length of the airbag were changed,and the acoustic source level frequency response curve of the transducer was simulated and calculated,verifying the accuracy of the theory;Simulate and analyze the opening height of the acoustic energy radiated by the transducer,and obtain relevant conclusions about the impact of the opening height on performance;Simulate the heat dissipation performance of the transducer and compare the heating speed of the inner coil structure of the transducer under different structures.Finally,the engineering design of the transducer was completed,and a prototype was made.The sound source level frequency response curves,and other tests were conducted in experimental pools and lakes at different depths to verify its acoustic performance characteristics.The test results showed that the performance of the transducer met theoretical expectations to a certain extent.