Broadband Longitudinal Vibration Transducer And Beam Width Research Techniques

With the stimulation of underwater acoustic countermeasure and sonar detection, thetechnology of underwater acoustic transducer develops rapidly. The broadband wide-beamlongitudinal vibration transducer plays an important role in the underwater transducer area.Although the longitudinal vibration transducer has relatively narrow-band and narrow-beam,some measures can be taken to make improvements. For the longitudinal vibration transducerwith a circular radiating surface, much research have been done to widen its band-width by theeffectively coulpling of longitudinal vibration mode and headmass bending mode, but littleresearch in longitudinal vibration transducer with a rectangle radiating surface. Also someresearches have been done in the technique to widen its beam, but the result differs.In allusion to the poor band-width and poor beam-width of the longitudinal vibrationtransducer, also the research actuality in and out of china, the paper mainly focuses on thecoupling of longitudinal vibration mode and headmass bending mode in longitudinal transducerwith a circular and rectangle radiating surface on the basis of the differences between the twokinds of longitudinal transducer, especially in the band-width and directivity of the transducerwith rectangle radiating surface of different proportion of width and length. The conception ofutilizing baffleplate boundary condition to widen beam was improved in the paper. The researchand analysis were confirmed by transducer experimenting and measurement.The experiment measurement shows that the transmitting voltage response-3dB band-widthof circular radiating surface transducer reaches9.5~18kHz with TVR135dB more or less andstable beam-width in fomer half of band-width and sudden reduction beam-width in latter half ofband-width. The transmitting voltage response-3dB band-width of the transducer with rectangleradiation surface of length and width proportion1.33:1reaches8~15.5kHz with the beam-widthdistributing between100degree and120degree averagely. The indraught of baffelplatedecreases or increases the beam-width of the transducer in some frequency. The results show that,the experiment results agree well with the calculated conclusions getting from ANSYS andATILA software.The theory and experiment results show: The coupling of longitudinal vibration mode andhead mass bending mode can effectively broaden the working band-width. By optimazing theparameters such as proportion of the length and width of the rectangle radiating surface,excellent performance can be realized of the transducer. The unaverage particle vibration caused by head-mass bending mode plays an important role in transducer directivity. The regulation ofthe beam-width changement in the circular and rectangle radiating surface tranducer are different.Optimization should be done accoroding to the requirement. The baffle-plate can effectivelyregulate transducer radiating sound field. The technique of utilizing baffle-plate to influencetransducer boundary condition so as to fulfill the aim of wide-beam is feasible.