Method for forecasting sensitivity of deep-sea spherical piezoelectric hydrophone

Abstract

The invention relates to a deep-sea spherical piezoelectric hydrophone sensitivity forecasting method, and the method comprises the steps: building an equivalent analysis model of a deep-sea spherical piezoelectric hydrophone, the equivalent analysis model comprises a piezoelectric model, a radiation model and a scattering model, and combining the three models to achieve the forecasting of the sensitivity of the deep-sea spherical piezoelectric hydrophone. According to the method, the sensitivity of the deep-sea spherical piezoelectric hydrophone can be forecasted based on the model on the basis of impedance characteristics under the condition that deep-sea acoustic measurement is not carried out.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater acoustic measurement, and particularly relates to a method for predicting dynamic changes of sensitivity of a deep-sea spherical piezoelectric hydrophone with hydrostatic pressure. BACKGROUND

[0002] With the continuous development of underwater acoustic technology, deep-sea underwater acoustic metrology technology plays an important role in guaranteeing the performance indicators of deep-sea underwater acoustic equipment and actual application. At present, the spherical piezoelectric hydrophone is an important standard sensor in deep-sea underwater acoustic metrology, which can not only accurately perceive and reproduce the underwater sound pressure value, but also stably generate underwater acoustic signals, and is widely used in deep-sea underwater acoustic metrology. Under deep-sea conditions, underwater acoustic measurement needs to be equipped with a special high-hydrostatic-pressure deep-sea environment simulation system to construct the measurement sound field conditions, and the measurement process is relatively complex and difficult to study, and the related research progress is relatively slow. At present, according to the different sound field environments, the main methods for measuring the sensitivity of the deep-sea spherical piezoelectric hydrophone include the coupled cavity reciprocity method, the standing wave tube comparison method, the traveling wave tube method, and the free field reciprocity method. These methods can measure the receiving sensitivity of the deep-sea spherical piezoelectric hydrophone, but they face certain technical difficulties: (1) The simulation of the high-hydrostatic-pressure deep-sea environment is complex and requires high equipment investment. The main method for measuring the sensitivity of the hydrophone at home and abroad is to simulate the high-hydrostatic-pressure deep-sea environment in the laboratory, which requires huge investment, a complex measurement process, and a long test cycle; (2) The sound field conditions required for measurement are strict, and wideband measurement is difficult. The standing wave tube comparison method and the coupled cavity reciprocity method can only measure the low-frequency sensitivity of the hydrophone in the sound pressure field, and the upper limit of the measurement frequency is usually 2 kHz. The free field reciprocity method can only measure the sensitivity of the hydrophone at medium and high frequencies, and the measurement frequency is usually above 5 kHz; (3) The development of a deep-sea low-frequency transmitting system is difficult. Under deep-sea conditions, it is difficult for the transmitting transducer required for sensitivity measurement to generate acoustic signals that meet the signal-to-noise ratio requirements due to the high hydrostatic pressure.

[0003] Therefore, there is an urgent need for a method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone to overcome the shortcomings of current deep-sea spherical piezoelectric hydrophone receiving sensitivity measurement. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone with hydrostatic pressure changes by impedance analysis, which can predict the sensitivity of a deep-sea spherical piezoelectric hydrophone without the need for a large pressure tank.

[0005] The technical solution of the present application is to provide a method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone, an equivalent analysis model of the deep-sea spherical piezoelectric hydrophone is established, the equivalent analysis model includes a piezoelectric model, a radiation model and a scattering model, and the three models are combined to realize the prediction of the sensitivity of the deep-sea spherical piezoelectric hydrophone, wherein,

[0006] The piezoelectric model and the radiation model can be equivalently represented in the form of a circuit, and when measuring the impedance, the expression is:

[0007]

[0008] In the formula, I is the excitation current when measuring the impedance of the deep-sea spherical piezoelectric hydrophone, V is the excitation voltage when measuring the impedance of the deep-sea spherical piezoelectric hydrophone, ω is the angular frequency, C0 is the static capacitance, is the electromechanical conversion coefficient, m is the equivalent mass, C m is the compliance coefficient, R m is the vibration loss, Z r is the radiation impedance,

[0009] The scattering model can be represented as:

[0010]

[0011] In the formula, p i is the incident wave in the sound field, p s is the scattered wave in the sound field, a is the radius of the deep-sea spherical piezoelectric hydrophone, and θ is the angle variable.

[0012] The sensitivity can be obtained based on the model, and the expression is:

[0013]

[0014] In the formula, R r is the radiation impedance, m s is the radiation resistance, and s is the area of the hydrophone.

[0015] The present application can realize the prediction of the sensitivity of the deep-sea spherical piezoelectric hydrophone without the need for a large pressure tank. Compared with the traditional method for measuring the sensitivity of the deep-sea spherical piezoelectric hydrophone, the present application establishes a precise measurement model and proposes a new idea for predicting the sensitivity of the deep-sea spherical piezoelectric hydrophone by using impedance characteristics, radiation characteristics and acoustic scattering characteristics, which further simplifies the process of measuring the deep-sea hydrophone and improves the efficiency. Based on the impedance characteristics, the sensitivity of the deep-sea spherical piezoelectric hydrophone can be predicted based on the model without deep-sea acoustic measurement.

[0016] As preferred, the impedance in the sensitivity expression can be obtained by the impedance characteristic, and the obtaining method is as follows:

[0017] (1) The admittance of the deep-sea spherical piezoelectric hydrophone can be expressed as:

[0018]

[0019] (2) Discretize the angular frequency ω of the admittance in formula (4) into a corresponding sequence, and the sequence is represented by i. Build the admittance propagation loss function E containing the parameters of the deep-sea spherical piezoelectric hydrophone n , which is expressed as:

[0020]

[0021] In the formula, Y id (i) is the target admittance function, Y io,n (i) is the estimated parameter after n iterations, and I is the total number of calculation points of the sequence;

[0022] (3) Combine the nonlinear least square estimation method to realize the estimation of each parameter in the admittance of the deep-sea spherical piezoelectric hydrophone.

[0023] As preferred, the specific operation steps are as follows:

[0024] S1, fix the deep-sea spherical piezoelectric hydrophone in a pressure vessel, apply hydrostatic pressure in the pressure vessel, and measure the admittance frequency response curve Y(ω) of the deep-sea spherical piezoelectric hydrophone under high hydrostatic pressure by using an impedance analyzer;

[0025] S2, establish a simulation model of the deep-sea spherical piezoelectric hydrophone in simulation software, and calculate the scattering coefficient frequency response γ(ω) of the deep-sea spherical piezoelectric hydrophone in the sound field;

[0026] S3, measure the diameter d of the deep-sea spherical piezoelectric hydrophone by using a vernier caliper, and calculate the area s of the deep-sea spherical piezoelectric hydrophone;

[0027] S4, use the nonlinear least square fitting algorithm to calculate the parameter values of C0(h), m(h), R m (h), C m (h), and Z r (h) in the equivalent model according to the admittance frequency response curve under different hydrostatic pressures h;

[0028] S5, bring the parameters obtained in the above steps S1, S2 and S3 into formula (3) to predict the sensitivity of the deep-sea spherical piezoelectric hydrophone.

[0029] As preferred, the pressure vessel is a small pressure vessel with a size of 100 cm*50 cm*50 cm or more.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] Based on the impedance characteristics, the sensitivity of the deep-sea spherical piezoelectric hydrophone can be predicted based on the model without deep-sea acoustic measurement, the characteristics of the deep-sea spherical piezoelectric hydrophone can be analyzed by using the equivalent circuit, and the sensitivity of the deep-sea spherical piezoelectric hydrophone can be predicted by using the equivalent model. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 An equivalent analysis model for the deep-sea spherical piezoelectric hydrophone.

[0033] Figure 2 A flowchart for parameter estimation of the deep-sea spherical piezoelectric hydrophone. DETAILED DESCRIPTION

[0034] The present application will be further described in conjunction with the specific embodiments and the accompanying drawings:

[0035] The present application discloses a method for predicting the dynamic change of the sensitivity of a deep-sea spherical piezoelectric hydrophone with hydrostatic pressure, which needs to establish an equivalent analysis model for the deep-sea spherical piezoelectric hydrophone, the equivalent analysis model includes a piezoelectric model, a vibration model and a scattering model, the combination of the three models can predict the sensitivity of the deep-sea spherical piezoelectric hydrophone, the equivalent analysis model is shown in Figure 1 , in which U is the open circuit voltage, I is the output current, C0 is the static capacitance, is the conversion coefficient, C m is the compliance coefficient, m is the equivalent mass, R m is the vibration loss, Zr is the radiation impedance, γ is the scattering coefficient, κ is the loss coefficient, p f is the sound pressure.

[0036] The measurement of the impedance or admittance of the deep-sea spherical piezoelectric hydrophone can be measured by a measurement system composed of a small pressure vessel with a size of 100cm*50cm*50cm or more, an impedance analyzer and the deep-sea spherical piezoelectric hydrophone, and the flowchart for parameter estimation of the deep-sea spherical piezoelectric hydrophone is shown in Figure 2

[0037] The specific operation steps of the method are as follows:

[0038] S1, fix the deep-sea spherical piezoelectric hydrophone in the pressure vessel, apply hydrostatic pressure in the pressure vessel, and measure the admittance frequency response curve Y(ω) of the deep-sea spherical piezoelectric hydrophone under high hydrostatic pressure by using the impedance analyzer;

[0039] S2, establish a simulation model of the deep-sea spherical piezoelectric hydrophone in the simulation software, and calculate the scattering coefficient frequency response γ(ω) of the deep-sea spherical piezoelectric hydrophone in the sound field.​

[0040] S3, the diameter d of the deep-sea spherical piezoelectric hydrophone is measured by using a vernier caliper, and the area s of the deep-sea spherical piezoelectric hydrophone is calculated;

[0041] S4, the parameter values of C0(h), m(h), R m (h), C m (h), Z r (h) in the equivalent model are calculated according to the admittance frequency response curves under different hydrostatic pressure h conditions by using a nonlinear least square fitting algorithm;

[0042] S5, the parameters obtained in the above steps S1, S2 and S3 are brought into formula (3),

[0043]

[0044] In the formula, M represents the sensitivity, R m is the vibration loss, R r is the radiation impedance, m is the equivalent mass, m s is the radiation impedance, s is the area of the hydrophone,

[0045] so as to predict the sensitivity of the deep-sea spherical piezoelectric hydrophone.

[0046] Compared with the traditional deep-sea spherical piezoelectric hydrophone sensitivity measurement method, the application establishes a precise measurement model, proposes a new idea of predicting the sensitivity of the deep-sea spherical piezoelectric hydrophone by using impedance characteristics, radiation characteristics and acoustic scattering characteristics, further simplifies the process of deep-sea hydrophone measurement, and improves the efficiency. The method can predict the sensitivity of the deep-sea spherical piezoelectric hydrophone in a non-acoustic pressure measurement system by using the model. An equivalent analysis model based on piezoelectric characteristics, radiation characteristics and acoustic scattering characteristics is established, nonlinear fitting technology is used to estimate the dynamic parameters of the deep-sea spherical piezoelectric hydrophone, and the scattering coefficient and the area are calculated by theoretical calculation and measurement. On this basis, combined with the working mechanism of the deep-sea spherical piezoelectric hydrophone, the sensitivity of the deep-sea spherical piezoelectric hydrophone under high hydrostatic pressure is predicted by using the parameters, which makes up for the deficiency of the current deep-sea underwater electroacoustic parameter measurement.

[0047] The above only describes the preferred embodiments of the application, but cannot be understood as limiting the claims. Any equivalent process transformation made by using the application description is included in the patent protection scope of the application.

Claims

1. A method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone, characterized by: An equivalent analysis model of deep-sea spherical piezoelectric hydrophone is established. The equivalent analysis model includes piezoelectric model, radiation model and scattering model. The three models are combined to predict the sensitivity of deep-sea spherical piezoelectric hydrophone. The piezoelectric model and radiation model can be equivalently expressed in the form of a circuit. When measuring their impedance, the expression is: Where, I is the excitation current when measuring the impedance of the deep-sea spherical piezoelectric hydrophone, V is the excitation voltage when measuring the impedance of the deep-sea spherical piezoelectric hydrophone, ω is the angular frequency, C0 is the static capacitance, is the electromechanical conversion coefficient, m is the equivalent mass, C m is the compliance coefficient, R m is the vibration loss, Z r is the radiation impedance, The scattering model can be expressed as: Where p i is the incident wave in the sound field, p s is the scattered wave in the sound field, a is the radius of the deep-sea spherical piezoelectric hydrophone, and θ is the angle variable; The sensitivity can be obtained based on the model, and the expression is: Where R r is the radiation impedance, m s is the radiation impedance, s is the area of ​​the hydrophone, 2. The method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone according to claim 1, characterized in that: The impedance in the sensitivity expression can be obtained through the impedance characteristics as follows: (1) The admittance of the deep-sea spherical piezoelectric hydrophone can be expressed as: (2) Discretize the angular frequency ω of the admittance in equation (4) into a corresponding sequence, represented by i, and construct the admittance propagation loss function E containing the parameters of the deep-sea spherical piezoelectric hydrophone n , expressed as: Where Y id (i) is the target admittance function, Y io,n (i) is the estimated parameter after n iterations, and I is the total number of calculation points in the sequence; (3) Combine the nonlinear least squares estimation method to realize the estimation of various parameters in the deep-sea spherical piezoelectric hydrophone admittance.

3. The method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone according to claim 1, characterized in that: The specific steps are as follows: S1, fix the deep-sea spherical piezoelectric hydrophone in a pressure vessel, apply hydrostatic pressure in the pressure vessel, and use an impedance analyzer to measure the admittance frequency response curve Y(ω) of the deep-sea spherical piezoelectric hydrophone under high hydrostatic pressure; S2, establish a simulation model of the deep-sea spherical piezoelectric hydrophone in the simulation software, and calculate the scattering coefficient frequency response γ(ω) of the deep-sea spherical piezoelectric hydrophone in the sound field; S3, using a vernier caliper to measure the diameter d of the deep-sea spherical piezoelectric hydrophone, and calculating the area s of the deep-sea spherical piezoelectric hydrophone; S4, using the nonlinear least squares fitting algorithm, according to the admittance frequency response curve under different hydrostatic pressure h conditions, the C0(h), m(h), R in the equivalent model are calculated. m (h), C m (h), Z r (h) parameter value; S5, substituting the parameters obtained in the above steps S1, S2 and S3 into equation (3) to predict the sensitivity of the deep-sea spherical piezoelectric hydrophone.

4. The method for predicting the sensitivity of a deep-sea spherical piezoelectric hydrophone according to claim 3, characterized in that: The pressure vessel is a small pressure vessel with a size of 100cm*50cm*50cm or more.

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