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Method for Measuring Self-noise of Vector Hydrophones 被引量:1
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作者 Zhi Li Hongjuan Chen 《Journal of Marine Science and Application》 CSCD 2017年第3期370-374,共5页
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
关键词 self-noise vector hydrophone acoustic measurement underwater transducer transfer function method
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Applicability of the Welch method for examining self-noise level parameters for broadband seismometers 被引量:3
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作者 Li Xiaojun Yang Dake +5 位作者 Xie Jianbo Ma Jiemei Yuan Songyong Xu Weiwei Zhao Jianhe Li Dongsheng 《Geodesy and Geodynamics》 2015年第3期233-239,共7页
Seismometer self-noise levels were determined using Sleeman’s three-sensor method in combination with the Welch method for different parameter combinations. The self-noise levels decreased with the increasing segment... Seismometer self-noise levels were determined using Sleeman’s three-sensor method in combination with the Welch method for different parameter combinations. The self-noise levels decreased with the increasing segment window length, which is equivalent to the subwindow length, and with the increasing segment overlap rate for different frequency points at a fixed band. After the statistical examination of 9800 different parameter combinations, a zone of reasonable self-noise calculation parameter combinations was identified. Reasons for the unsuitability of certain parameter combinations were explored with respect to their distortion of the seismometer’s self-noise levels. 展开更多
关键词 self-noise Seismometer Welch method Applicability
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Numerical simulation on the NACA0018 airfoil self-noise generation 被引量:4
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作者 Min Jiang Xiaodong Li +1 位作者 Baohong Bai Dakai Lin 《Theoretical & Applied Mechanics Letters》 2012年第5期39-42,共4页
Airfoil self-noise is a common phenomenon for many engineering applications. Aiming to study the underlying mechanism of airfoil self-noise at low Mach number and moderate Reynolds number flow, a numerical investigati... Airfoil self-noise is a common phenomenon for many engineering applications. Aiming to study the underlying mechanism of airfoil self-noise at low Mach number and moderate Reynolds number flow, a numerical investigation is presented on noise generation by flow past NACA0018 airfoil. Based on a high-order accurate numerical method, both the near-field hydrodynamics and the far-field acoustics are computed simultaneously by performing direct numerical simulation. The mean flow properties agree well with the experimental measurements. The characteristics of aerodynamic noise are investigated at various angles of attack. The obtained results show that inclining the airfoil could enlarge turbulent intensity and produce larger scale of vortices. The sound radiation is mainly towards the upper and lower directions of the airfoil surface. At higher angle of attack, the tonal noise tends to disappear and the noise spectrum displays broad-band features. 展开更多
关键词 direct numerical simulation computational aeroacoustics airfoil self-noise broad-band features
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Underwater vehicle sonar self-noise prediction based on genetic algorithms and neural network
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作者 WU Xiao-guang SHI Zhong-kun 《Journal of Marine Science and Application》 2006年第2期36-41,共6页
The factors that influence underwater vehicle sonar self-noise are analyzed, and genetic algorithms and a back propagation (BP) neural network are combined to predict underwater vehicle sonar self-noise. The experimen... The factors that influence underwater vehicle sonar self-noise are analyzed, and genetic algorithms and a back propagation (BP) neural network are combined to predict underwater vehicle sonar self-noise. The experimental results demonstrate that underwater vehicle sonar self-noise can be predicted accurately by a GA-BP neural network that is based on actual underwater vehicle sonar data. 展开更多
关键词 sonar self-noise back propagation (BP) neural network genetic algorithms
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Prediction and test of cavity's hydrodynamic self-noise induced by turbulent boundary layer
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作者 LIU Xiaobin Lü Shijin YU Mengsa 《Chinese Journal of Acoustics》 CSCD 2016年第2期147-154,共8页
The self-noise in cavity is tested in the circling tank, prediction method of cavity's self-noise induced by turbulent boundary layer is established. The window's vibration is using the simply supported boundary con... The self-noise in cavity is tested in the circling tank, prediction method of cavity's self-noise induced by turbulent boundary layer is established. The window's vibration is using the simply supported boundary condition, the sound wave in the cavity is expanded using the rigid wall boundary condition, the modal coupling vibration equation between them is established using the radiation boundary condition. The turbulent boundary layer pulsating pressure is random, the self-noise power spectrum in the cavity is solved. Test of self-noise and turbulent pressure is carried out in the circling tank when the flow velocity is 5 m/s and 8 m/s, the result verifies that the theoretical method can predict the real cavity's hydrodynamic noise approximately, the trends are similar, this provides one analytical method for sonar dome's material selection and noise control. 展开更多
关键词 Prediction and test of cavity’s hydrodynamic self-noise induced by turbulent boundary layer
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Experimental and Numerical Procedures of a Sonar Platform with a Sound Absorption Wedge
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作者 Danzhu Yu Xiongliang Yao Shaoshi Dai 《Journal of Marine Science and Application》 2011年第3期364-370,共7页
Experiments involving a sonar platform with a sound absorption wedge were carried out for the purpose of obtaining the low frequency acoustic characteristics. Acoustic characteristics of a sonar platform model with a ... Experiments involving a sonar platform with a sound absorption wedge were carried out for the purpose of obtaining the low frequency acoustic characteristics. Acoustic characteristics of a sonar platform model with a sound absorption wedge were measured, and the effects of different wedge laid areas on platform acoustic characteristic were tested. Vibration acceleration and self-noise caused by model vibration were measured in four conditions: 0%, 36%, 60%, and 100% of wedge laid area when the sonar platform was under a single frequency excitation force. An experiment was performed to validate a corresponding numerical calculation. The numerical vibration characteristics of platform area were calculated by the finite element method, and self-noise caused by the vibration in it was predicted by an experiential formula. The conclusions prove that the numerical calculation method can partially replace the experimental process for obtaining vibration and sound characteristics. 展开更多
关键词 sound absorption wedge sonar platform area costal experiment of model self-noise numerical calculation
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