Research On Conformal Driving Low-frequency Transducer

Flextensional transducer is a kind of low-frequency and high-power projector widely used underwater.In view of the urgent demand for small size,light weight and low frequency projectors in the fields of medium and small target platforms in recent years,this paper mainly studies how to further reduce the frequency of flextensional transducers in tensile body to achieve low frequency,high power and directivity under small size.For the flextensional transducer,the intrinsic vibration mode frequency of the shell is lower,but the equivalent stiffness of the transducer is greatly increased by adding the ceramic pile driving structure of the long beam,so that the resonant frequency of the transducer is increased more.In view of the problem that the long beam drive structure brings about the increase of frequency,this paper proposes a conformal drive mode--conformal drive that realizes conformal drive with the shell structure.Then the conformal drive mode has been studied and designed,so as to make the respiratory vibration mode frequency of the flextensional shell not increase too much.Thus,the performance of reducing the working frequency of the flexural transducer under the same size has been achieved.Due to the new conformal driving structure and shell,the driving forms are more diverse.This paper studies the performance of conformal driving transducers with different structural forms,designs three flexural transducers with different characteristics and structures,and realizes the performance of low frequency,high power and directivity.The type ? flextensional transducer is relatively simple in structure and is widely used.Therefore,the application of conformal drive on the type ? flextensional transducer shell based on the type ? flextensional transducer model has been studies in this paper firstly.The main vibration modes and characteristics of conformal drive oval-ring transducer are analyzed.According to the basic model of the vibration characteristic,furthermore,a subsection driven model of high-power radiation is proposed.The electroacoustic characteristics of the transducer in air and water are analyzed,and the influence of structural parameters on vibration and radiation characteristics is analyzed.Finally,the methods to reduce working frequency have been summarized.The conformal drive oval-ring transducer is about 45%lower than the type ? flextensional transducer.It is concluded that the conformal drive has higher quality factors of volume and weight and better comprehensive performance a flextensional transducerer the calculation.Secondly,the application of conformal drive is studied on trigonal transducers.The basic vibration modes of conformal drive trigonal transducers are explored,and the vibration displacement characteristics of the radiant surface of the transducers are analyzed.The effect on the resonant frequency and the transmitted voltage response by changing the main structure parameters has been analyzed.The resonant frequency of conformal drive trigonal transducer is about 30%lower than that of conventional drive trigonal transducer.The simulation results show that the conformal drive trigonal transducer can also achieve low frequency,small size and high power operation.Then the directivity model of conformal drive oval-ring transducer is proposed and the directivity radiation of conformal drive oval-ring transducer is studied by applying mode superposition principle.Based on the vibration modes of the basic structure of the elliptical shell,first two order vibration modes with omnidirectional and dipole characteristics is determined.Therefore,a conformal driving oval-ring transducer can realize the radiation properties of omnidirectional,dipole and heart-shaped directional transducers by applying the principle of mode superposition.Based on the analysis of the influence of the boundary conditions of the transducer on the fundamental vibration mode of the transducer's directivity,it is concluded that when the long axis edge of the elliptical shell is rigidly fixed,it is easier to use the mode superposition principle,which can result in better directivity performance and higher radiation efficiency.Finally,the prototype of conformal drive oval-ring transducer and conformal drive trigonal transducer were made,and the relevant characteristics were tested in the air and the muffler respectively.The resonant frequency of conformal drive oval-ring transducer in water was measured to be 520Hz and the maximum transmitted voltage response value was 135.4dB,which realized the characteristics of low frequency,small size and large power of the transducer.The resonance frequency in water of conformal drive trigonal transducers is measured to be 1080Hz,and the maximum transmitted voltage response value is 119.9dB.The application of conformal drive in trigonal transducers is also obtained,which can reduce the working frequency of transducers.On the prototype model of conformal drive oval-ring transducer,the resonance frequency in the water of the transducer was measured to be 1480Hz under the drive of mode synthesis to form a heart-shaped directivity,and the transducer formed a relatively obvious heart-shaped directivity at this frequency,with a maximum pit depth of 8dB and One-way radiation sound field distribution.The conformal drive provides a new method for the flextensional transducer to realize low-frequency,small-size and high-power work.It has a wide range of research contents to be explored and a broad application prospect.