| Underwater acoustic transducer is the most basic acoustic equipment unit in the field of underwater acoustic application.Its working performance is of great significance to the application of underwater acoustic technology in practical engineering.The use of reverberation field to calibrate hydrophone in reverberation pool has the advantages of simple calibration steps and accurate and reliable results.In recent years,the development of underwater acoustics puts forward an urgent demand for the establishment of reverberation field hydrophone calibration system with low cost,high efficiency and easy construction and maintenance under laboratory conditions,At present,the calibration technology of low-frequency reverberation sound field of hydrophone in the low-frequency range of 0-20 k Hz has become mature,but the relevant research work on the calibration technology of higher frequency hydrophone in reverberation tank has not been carried out.In this paper,the calibration technology of hydrophone under the high-frequency condition of 20 k Hz-50 k Hz in reverberation tank is studied,which is of great significance to improve the underwater acoustic measurement system in the field of engineering application.There is a linear relationship between the spatial mean square sound pressure and the sound power radiated by the sound source in the reverberation control area of the reverberation pool,which provides an ideal sound field condition for the calibration of hydrophone under the condition of high-frequency sound field.Under the condition of high-frequency sound field,the reverberation sound energy attenuation and high-frequency limit caused by medium sound absorption can be effectively solved by reducing the volume of the water tank.The theoretical research results show that the spatial average technology and frequency average technology have a good effect on improving the high-frequency calibration accuracy in the reverberation tank.The principles and steps of the calibration of reciprocity method and comparison method under the condition of high-frequency sound field in the reverberation tank are deduced and given.The larger the frequency average bandwidth in the reverberation pool,the more the modal number and modal density in the band,and the more obvious the effect of frequency average in eliminating the interference fluctuation of sound field;The distance between discrete spatial average observation points should be at least half wavelength.The more uncorrelated spatial observation points,the better the effect of spatial average to eliminate the interference fluctuation of sound field.The experimental results show that the 200 cm continuous space average in the calibration frequency range of 20 k Hz 50 k Hz can reduce the relative standard deviation of repeated measurement of sound pressure level to 0.15%,and the average in 1 / 3 octave band can reduce the relative standard deviation of measurement results to 0.08%.The relative standard deviation of repeated measurement of sound pressure level is less than 0.14% in the range of 20 k Hz-50 k Hz.In this paper,the high frequency calibration system of hydrophone in reverberation tank based on small volume glass water tank meets the conditions of high frequency calibration.In this paper,the sound pressure sensitivity of B&K-8103 hydrophone is calibrated in the frequency range of 20 k Hz-50 k Hz.The calibration results show that the calibration error of reverberation pool reciprocity high frequency calibration system is less than 1.0d B in the frequency range of 20 k Hz-50 k Hz,and the synthetic uncertainty is less than 0.85 d B.The calibration error of the high-frequency calibration system of reverberation pool comparison method is less than 1.1d B in the range of 20 k Hz-50 k Hz,and the synthetic uncertainty is less than 0.68 d B.The research results show that the high-frequency calibration system of reverberation pool hydrophone in this paper has high calibration accuracy,low uncertainty and high practicability. |
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