Research On Rigidly Mounted Second Order Acoustic Vector Hydrophone

With the application demand,the performance of vector hydrophone puts forward higher requirements.Today,the traditional hydrophone or metal spring suspension vector hydrophone due to the suspension of the inconvenience can not meet the actual application scenarios.Furthermore,due to the richness of the vector information of the sound field,it is necessary to receive the higher order physical quantities to satisfy the deeper research on the sound field.Therefore,this paper designed a fixed-mounted second-order acoustic vector hydrophone to solve the purpose of convenient installation and measurement of second-order underwater sound field.The first is to analyze the physical quantities of different orders in the sound field.The estimated range of the sound pressure field under a given error condition is given by using the Taylor expansion.With a mean square error of 10%,the range of the sound field with a diameter of 0.14 wavelengths can be estimated using the zero order physical quantities.Using zero,first-order physical quantities we can estimate the range of 0.32 wavelength in diameter.Using zero,one,two physical quantities can be estimated to a diameter of 0.49 wavelength range.The relationship between the measurement error and each parameter is analyzed theoretically when the differential is used instead of the differential measurement.The differential distance will only produce error in the amplitude measurement,and the sensitivity mismatch will produce large errors in amplitude and phase.The hydrophone Positioning errors will produce large errors in amplitude,while the impact on the phase is not.Through the adjustment of various parameters to control the measurement error sizeThen,a fixed-mounted second-order acoustic vector hydrophone is designed.The second-order acoustic vector hydrophone and acceleration vector hydrophone are simulated by Comsol software.Modal,sensitivity and directivity are analyzed.At 3400 Hz The following reception performance is consistent with the theory.In addition,the method of theoretical derivation and simulation analysis is used to study the second-order sound field measurement.The theoretical error analysis and simulation results are in good agreement.By analyzing the influence of structural parameters on the receiving performance,the design criteria of the second-order acoustic vector hydrophone are given.Finally,the prototype of the fixed-mounted second-order acoustic vector hydrophone is studied,and the electro-acoustic performance is tested in the pool.The sensitivity of the two vector hydrophone units is close to-187.5dB at 1kHz.The second-order pure gradient sensitivity is-191 dB at 1 kHz,the second-order hybrid gradient sensitivity is-193 dB at 1 kHz,and both sensitivity slopes are close to 11 dB/oct,which is in good agreement with the theoretically calculated 12 dB/oct.The use of fixed-mounted second-order acoustic vector hydrophone can solve the inconvenient use of vector hydrophone in practical applications and support underwater sound field research by measuring the second-order gradient in sound field.