The Vector Hydrophone(VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which...The Vector Hydrophone(VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which it is utilized, since the ability to acquire weak signals is determined by the VH self-noise level. To accurately measure the VH self-noise level in actual working conditions, the Dual-channel Transfer Function Method(DTFM) is proposed to reduce ambient background noise interference. In this paper, the underlying principles of DTFM in reducing ambient background noise is analyzed. The numerical simulations to determine the influence of ambient background noise, and the sensitivity difference of the two VHs on the measurement results are studied. The results of measuring the VH self-noise level in a small laboratory water tank by using DTMF indicate that ambient background noise interference can be reduced effectively by employing DTMF, more accurate self-noise level can be obtained as well. The DTMF provides an effective method for accurately measuring the self-noise level of VHs and also provides technical support for the practical application of the VH in underwater acoustics.展开更多
Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design criterion.Howeve...Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design criterion.However,hydrodynamic performances should also be considered before a decision to use these propellers is made.This study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating case.Many papers in the literature focus solely on hydroacoustic calculations for the open-water case.However,propulsive characteristics are significantly different when propeller-hull interactions take place.Changes in propulsion performance also reflect on the hydroacoustic performances of the propeller.In this study,propeller-hull interactions were considered to calculate the noise spectra.Rather than solving the full case,which is computationally demanding,an indirect approach was adopted;axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach.A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods,implementing the Ffowcs Williams-Hawkings(FW-H)equation.The hydrodynamic performances of both propellers were presented as a preliminary study.Propeller-hull interactions were included in calculations after observing good accordance between our results,experiments,and quasi-continuous method for the open-water case.With the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input,simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near field.Noise spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the present method are in good accordance with the theoretical values.Results also show that a highly skewed propeller generates less noise even in noncavitating cases despite a small reduction in hydrodynamic efficiency.展开更多
Cymbal hydrophones have small volume and high sensitivity, but their reception is not stable enough, and their reception is in too narrow a frequency band. In order to overcome these inadequacies, the structure of the...Cymbal hydrophones have small volume and high sensitivity, but their reception is not stable enough, and their reception is in too narrow a frequency band. In order to overcome these inadequacies, the structure of the cymbal hydrophone was improved. The single ceramic piezoelectric element was replaced with a double one, the radius of the ceramic piezoelectric element was reduced, and a parallel circuit was added. A static analysis of this new structure was developed, and then simulations were made of both the traditional and new hydrophone structure using finite element software. Tests were then conducted in a tank. The results showed that the improved hydrophone has reception in a wider frequency band, reception performance is stable within this frequency band, and sensitivity is still high.展开更多
A bionic fish cilia median-low frequency three-dimensional MEMS vector hydrophone is reported in this paper. The piezoresistive reasonable position was obtained through finite element analysis by ANSYS and the structu...A bionic fish cilia median-low frequency three-dimensional MEMS vector hydrophone is reported in this paper. The piezoresistive reasonable position was obtained through finite element analysis by ANSYS and the structure was formed by MEMS processes including lithography, ion implantation, PECVD and etching,etc. The standing wave barrel results show that the lowest sensitivity of the hydrophone is-200 d B and reach up to-160 d B(in which the voltage amplification factor is 300). It has a good frequency response characteristics in 25 Hz ～ 1500 Hz band. Directivity tests displayed that the hydrophone has a good "8"-shaped directivity,in which the resolution is not less than 30 d B, and asymmetry of the maximum axial sensitivity value is less than 1.2 d B.展开更多
The flow noise associated with sinusoidal vertical motion of a sonobuoy restrains its working performance.In practice,a suspension system consisting of elastic suspension cable and isolation mass is adopted to isolate...The flow noise associated with sinusoidal vertical motion of a sonobuoy restrains its working performance.In practice,a suspension system consisting of elastic suspension cable and isolation mass is adopted to isolate the hydrophone from large vertical motions of the buoy on the ocean surface.In the present study,a theoretical model of vertical motion based on the sonobuoy suspension system was proposed.The vertical motion velocity response of the hydrophone of a sonobuoy can be obtained by solving the theoretical model with Runge-Kutta algorithm.The flow noise of the hydrophone at this response motion velocity was predicted using a hybrid computational fluid dynamics(CFD)-Ffowcs Williams-Hawkings(FW-H)technique.The simulation results revealed that adding the elastic suspension cable with an appropriate elastic constant and counterweight with an appropriate mass have a good effect on reducing the flow noise caused by the sonobuoy vertical motion.The validation of this hybrid computational method used for reliable prediction of flow noise was also carried out on the basis of experimental data and empirical formula.The finds of this study can supply the deep understandings of the relationships between flow noise reduction and sonobuoy optimization.展开更多
To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The r...To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The radioactivity of the proposed hydrophone is strictly controlled by selecting pure raw materials, especially active piezoelectric ceramics. The electroacoustic performance of the hydrophone is improved by making structural optimization. High sensitivity and aimed directivity are achieved using 33-mode piezoelectric ceramic rings arranged in series and improvement in the radiating head of the Tonpilz hydrophone, respectively. All electroacoustic performances are studied through finite element analyses.The simulations indicate that the electroacoustic performances of the hydrophones in linear alkylbenzene-based liquid scintillator can be approximately predicted according to the results in water because their differences caused by two types of acoustic media, water and liquid scintillator, are known. The tests show that the hydrophone prototype can achieve a maximum sensitivity of-209.3dB and a beamwidth of 132.2° at a frequency of 143 kHz.In addition, eight hydrophones only contributed to a background radioactivity level of 26 ± 4 mHz in the neutrino analysis.展开更多
Lanthanum-modified lead zirconate titanite （PLZT） piezoelectric ceramics has higher piezoelectric and dielectric properties compared with the common lead zirconate titanite （PZT） ceramics. These properties endue t...Lanthanum-modified lead zirconate titanite （PLZT） piezoelectric ceramics has higher piezoelectric and dielectric properties compared with the common lead zirconate titanite （PZT） ceramics. These properties endue the cymbal hydrophones made of PLZT usually with stable performance but lower receiving sensitivity. In order to improve the sensitivity, through a static analysis on hydrophone we did some changes for the PLZT hydrophone by reducing the radius of the piezoelectric ceramics and sealing its boundary. Furthermore, ANSYS simulations were made, and the experiments for the improved PLZT hydrophone and the original one were carried out in water pool. The results show that the receiving sensitivity of the improved cymbal hydrophone made of PLZT is 3 -4 dB higher than that of the original, and that the frequency response still keeps flat within 18 kHz band.展开更多
A fiber Bragg grating （FBG） hydrophone with enhanced sensitivity is demonstrated. A novel piston-like diaphragm with a hard core fixed at the center is used as the sensing element. Theoretical analysis shows that th...A fiber Bragg grating （FBG） hydrophone with enhanced sensitivity is demonstrated. A novel piston-like diaphragm with a hard core fixed at the center is used as the sensing element. Theoretical analysis shows that the Young＇s modulus of the diaphragm and the radius of the hard core have significant effect on the pressure sensitivity. Experiments are carried out to test this effect and the performance of the hydrophone. The static measure- ment result is in good agreement with the theoretical result and an acoustic sensitivity of 7 nm/MPa has been achieved.展开更多
文摘The Vector Hydrophone(VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which it is utilized, since the ability to acquire weak signals is determined by the VH self-noise level. To accurately measure the VH self-noise level in actual working conditions, the Dual-channel Transfer Function Method(DTFM) is proposed to reduce ambient background noise interference. In this paper, the underlying principles of DTFM in reducing ambient background noise is analyzed. The numerical simulations to determine the influence of ambient background noise, and the sensitivity difference of the two VHs on the measurement results are studied. The results of measuring the VH self-noise level in a small laboratory water tank by using DTMF indicate that ambient background noise interference can be reduced effectively by employing DTMF, more accurate self-noise level can be obtained as well. The DTMF provides an effective method for accurately measuring the self-noise level of VHs and also provides technical support for the practical application of the VH in underwater acoustics.
基金The third author acknowledges the financial support from the Scientific and Technological Research Council of Turkey(TUBITAK),Project ID:218 M372.
文摘Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design criterion.However,hydrodynamic performances should also be considered before a decision to use these propellers is made.This study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating case.Many papers in the literature focus solely on hydroacoustic calculations for the open-water case.However,propulsive characteristics are significantly different when propeller-hull interactions take place.Changes in propulsion performance also reflect on the hydroacoustic performances of the propeller.In this study,propeller-hull interactions were considered to calculate the noise spectra.Rather than solving the full case,which is computationally demanding,an indirect approach was adopted;axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach.A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods,implementing the Ffowcs Williams-Hawkings(FW-H)equation.The hydrodynamic performances of both propellers were presented as a preliminary study.Propeller-hull interactions were included in calculations after observing good accordance between our results,experiments,and quasi-continuous method for the open-water case.With the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input,simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near field.Noise spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the present method are in good accordance with the theoretical values.Results also show that a highly skewed propeller generates less noise even in noncavitating cases despite a small reduction in hydrodynamic efficiency.
文摘Cymbal hydrophones have small volume and high sensitivity, but their reception is not stable enough, and their reception is in too narrow a frequency band. In order to overcome these inadequacies, the structure of the cymbal hydrophone was improved. The single ceramic piezoelectric element was replaced with a double one, the radius of the ceramic piezoelectric element was reduced, and a parallel circuit was added. A static analysis of this new structure was developed, and then simulations were made of both the traditional and new hydrophone structure using finite element software. Tests were then conducted in a tank. The results showed that the improved hydrophone has reception in a wider frequency band, reception performance is stable within this frequency band, and sensitivity is still high.
基金supported by the National Science Foundation of China (51205374, 61127008)Shanxi province Science foundation for Youths (2012021013-3)
文摘A bionic fish cilia median-low frequency three-dimensional MEMS vector hydrophone is reported in this paper. The piezoresistive reasonable position was obtained through finite element analysis by ANSYS and the structure was formed by MEMS processes including lithography, ion implantation, PECVD and etching,etc. The standing wave barrel results show that the lowest sensitivity of the hydrophone is-200 d B and reach up to-160 d B(in which the voltage amplification factor is 300). It has a good frequency response characteristics in 25 Hz ～ 1500 Hz band. Directivity tests displayed that the hydrophone has a good "8"-shaped directivity,in which the resolution is not less than 30 d B, and asymmetry of the maximum axial sensitivity value is less than 1.2 d B.
基金This work was supported by the National Natural Science Foundation of China(Grant No.61901383)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2019JQ633)+2 种基金the Fundamental Research Funds for the Central University(Grant No.3102019HHZY030011)China Postdoctoral Science Foundation(2019M663822)the Open Fund Project of Key Laboratory of Marine Environmental Information Technology,Ministry of Natural Resources of the People’s Republic of China.
文摘The flow noise associated with sinusoidal vertical motion of a sonobuoy restrains its working performance.In practice,a suspension system consisting of elastic suspension cable and isolation mass is adopted to isolate the hydrophone from large vertical motions of the buoy on the ocean surface.In the present study,a theoretical model of vertical motion based on the sonobuoy suspension system was proposed.The vertical motion velocity response of the hydrophone of a sonobuoy can be obtained by solving the theoretical model with Runge-Kutta algorithm.The flow noise of the hydrophone at this response motion velocity was predicted using a hybrid computational fluid dynamics(CFD)-Ffowcs Williams-Hawkings(FW-H)technique.The simulation results revealed that adding the elastic suspension cable with an appropriate elastic constant and counterweight with an appropriate mass have a good effect on reducing the flow noise caused by the sonobuoy vertical motion.The validation of this hybrid computational method used for reliable prediction of flow noise was also carried out on the basis of experimental data and empirical formula.The finds of this study can supply the deep understandings of the relationships between flow noise reduction and sonobuoy optimization.
基金supported by the“trategic Priority Research Program”of the Chinese Academy of Sciences(No.XDA10010800)the National Natural Science Foundation of China(No.12074318)。
文摘To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The radioactivity of the proposed hydrophone is strictly controlled by selecting pure raw materials, especially active piezoelectric ceramics. The electroacoustic performance of the hydrophone is improved by making structural optimization. High sensitivity and aimed directivity are achieved using 33-mode piezoelectric ceramic rings arranged in series and improvement in the radiating head of the Tonpilz hydrophone, respectively. All electroacoustic performances are studied through finite element analyses.The simulations indicate that the electroacoustic performances of the hydrophones in linear alkylbenzene-based liquid scintillator can be approximately predicted according to the results in water because their differences caused by two types of acoustic media, water and liquid scintillator, are known. The tests show that the hydrophone prototype can achieve a maximum sensitivity of-209.3dB and a beamwidth of 132.2° at a frequency of 143 kHz.In addition, eight hydrophones only contributed to a background radioactivity level of 26 ± 4 mHz in the neutrino analysis.
文摘Lanthanum-modified lead zirconate titanite （PLZT） piezoelectric ceramics has higher piezoelectric and dielectric properties compared with the common lead zirconate titanite （PZT） ceramics. These properties endue the cymbal hydrophones made of PLZT usually with stable performance but lower receiving sensitivity. In order to improve the sensitivity, through a static analysis on hydrophone we did some changes for the PLZT hydrophone by reducing the radius of the piezoelectric ceramics and sealing its boundary. Furthermore, ANSYS simulations were made, and the experiments for the improved PLZT hydrophone and the original one were carried out in water pool. The results show that the receiving sensitivity of the improved cymbal hydrophone made of PLZT is 3 -4 dB higher than that of the original, and that the frequency response still keeps flat within 18 kHz band.
基金supported by the National 863 Program under Grant No. 2007AA03Z415.
文摘A fiber Bragg grating （FBG） hydrophone with enhanced sensitivity is demonstrated. A novel piston-like diaphragm with a hard core fixed at the center is used as the sensing element. Theoretical analysis shows that the Young＇s modulus of the diaphragm and the radius of the hard core have significant effect on the pressure sensitivity. Experiments are carried out to test this effect and the performance of the hydrophone. The static measure- ment result is in good agreement with the theoretical result and an acoustic sensitivity of 7 nm/MPa has been achieved.
