Research On Broadband Transducer With Rectangular Through Hole In Front Cover

Experience the ocean,advance into the deep blue,and equip first.With the continuous deepening of our country's ocean exploration,the development of underwater acoustic equipment has also entered a new stage,and as the "eyes" of underwater detection equipment-underwater acoustic transducers are also used in marine environmental scientific research,civil navigation and military affairs.An indispensable part of the aspect.Broadband underwater acoustic transducers can have a flatter frequency response in a wider frequency range.When modern information processing such as pulse compression is used to ensure that the signal does not undergo waveform distortion,the bit error rate is reduced,the reliability is improved,and it is also higher.Its time-domain resolution and strong adaptability to external load changes make it widely used.The innovation of the research content in this paper is to use the principle of multimode coupling to propose a structure in which a horizontal rectangular through hole is opened on the front cover of the traditional longitudinal vibration transducer to excite more effective working modes,and through optimization The position and geometric size of the through holes are used to adjust the relative position and height of the resonance peaks to avoid too deep valleys to achieve the purpose of widening the working frequency band.The advantage of this structure is that it can significantly broaden the frequency band while retaining the flatness of the radiation end surface of the front cover.Since the perforated transducer itself is still a sandwich transducer,it also has the characteristics of high efficiency,stable performance,and large power capacity.In addition,the calculation and test results show that the overflow hole does not produce reverse vibration and the directivity is 8-shaped.The contributions and research results of the thesis are as follows:First,a brief overview of the underwater acoustic transducer,the background of the topic and the significance of the research are given.Then,around the index requirement of improving the broadband performance of the transducer,scholars at home and abroad have carried out a lot of research.There are many ways to broaden the bandwidth,and these methods have their own characteristics.Then,several research methods of the transducer are briefly described.The classical equivalent circuit method is used to derive the electromechanical equivalent circuit diagram of each part of the composite rod-type longitudinal vibration transducer,and on this basis,the frequency equation for the design of the transducer is given.Then according to the actual purpose and use environment,several important performance indicators for measuring the transducer are given.The COMSOL Multiphysics finite element simulation software was used to establish the finite element model of the solid transducer and the open-hole transducer of the same size,and the frequency domain research and the characteristic frequency research were carried out.The admittance curves of the two transducers in air and the vibration modes in air are calculated.Then the emission voltage response and directivity of the two transducers in water are calculated.Finally,with the goal of wideband,the three variables of the length and width of the through hole and the distance between the front end of the hole and the end surface of the front cover are changed,and the influence of each variable on the resonance frequency and bandwidth is calculated and analyzed.It can be seen from the calculation result that the length of the hole has a greater influence on the second resonant frequency,and the resonant frequency first increases and then decreases as the length increases,while the corresponding transmit voltage response value remains basically unchanged.The width of the hole has a great influence on the first resonant frequency value and the corresponding emission voltage response value,and both decrease as the width increases.The distance between the front end of the hole and the end surface of the cover plate has a great influence on the last two resonant frequency values,and the two resonant frequencies both increase with the increase of the distance.The directivity map of the transducer in the plane vertical and horizontal to the through hole is calculated.The result shows that as the frequency increases,the main lobe gradually narrows,the side lobes become larger,and the backward radiation of the transducer becomes obvious.Finally,an open-hole wide-band transducer is developed according to the optimal hole size after the finite element software optimization calculation.The impedance analyzer measured the impedance curve of the transducer in the air,and the laser vibrometer measured the vibration displacement of the radiating end face of the transducer at three resonance frequencies.Compared with the simulation calculation results,the displacement distribution at the radiating end face was basically Unanimous.The emission voltage response and the two-dimensional directivity diagram of the transducer were tested in the anechoic tank.The results show that the maximum emission voltage response value of the unopened solid transducer in the frequency range of 20kHz?23kHz is 146 dB,in-band Fluctuation of 3dB;in the 22kHz?32.5kHz frequency band,the maximum emission voltage response of the open-hole transducer is 141dB,and the in-band fluctuation is 3dB.The theoretical calculation is in good agreement with the experimental test results.In the article,the error of the two is analyzed.