Research On Calibration Method Of Vector Hydrophone Sensitivity In Water Tank

The receiving sensitivity of a hydrophone is an important indicator for measuring its acoustic performance.With the emergence of low-frequency large-scale vector hydrophones,conventional standing wave tubes cannot perform hydrophone calibration due to size limitations;Due to the limitation of boundary conditions in the anechoic pool,the pulse acoustic technology cannot separate the direct wave from the reflected wave in the time domain.For these two cases,the paper studied two methods for measuring the free-field sensitivity of vector hydrophones based on transient signals and the sound pressure sensitivity of vector hydrophones based on standing wave fields in a water tank.For the study of the free-field sensitivity measurement method of the vector hydrophone based on transient signals in the water tank,the paper first used geometric acoustics to study the sound pressure spatial distribution characteristics of the point source sound field in the water tank,and simulated the influence of the placement position of the transducer on its distribution characteristics.Secondly,taking the single resonant piezoelectric transmitter as an example,starting from the vibration equation of the radiation surface,the analytical solution of the vibration displacement of the radiation surface at the resonant frequency point of the transmitter under sinusoidal pulse signal excitation was analyzed,and the relationship between the transient part and the steady-state part amplitude of the received signal was determined.Using COMSOL finite element software,the modal analysis,harmonic response analysis and transient analysis of commonly used transmitters are carried out to determine the selection of sound sources and the position of receiving points;Building an experimental platform and using the comparison method to measure the sound pressure sensitivity of the vector hydrophone in the water tank.This measurement method overcomes the influence of space size and expands the lower limit of calibration of vector hydrophones in limited space.For the sound pressure sensitivity measurement method of the vector hydrophone based on the standing wave field in a small water tank,the paper first analyzed the standing wave sound field in the water tank based on the rectangular waveguide and derived the calibration formula for the sound pressure sensitivity of the vector hydrophone in the standing wave sound field of the water tank.Using COMSOL finite element software,the modal analysis and harmonic response analysis of the water tank are carried out to determine the placement area of the sound source and the vector hydrophone,as well as the frequency band range of the measured vector hydrophone in the water tank.Building an experimental platform to verify the sound field in the water tank and using the comparison method to measure the sound pressure sensitivity of the vector hydrophone.Experimental data shows that it is completely feasible to measure the sound pressure sensitivity of the vector hydrophone in the standing wave field of the water tank.