Low frequency calibration device for hydrophone under variable temperature condition

Abstract

The present application belongs to the technical field of underwater acoustic measurement and testing, and particularly relates to a hydrophone low-frequency calibration device under variable temperature conditions, which comprises a moving coil outer cylinder, a moving coil inner cylinder, a support bottom plate and a piston generator. The support bottom plate is a square plastic plate, four corners of which are provided with threaded holes, and the center of the support bottom plate is provided with four countersunk holes. Four support columns are connected to the piston generator through four bolts. The piston generator is located above the support bottom plate and is connected to the moving coil outer cylinder through magnetism and a bolt and a nut. The moving coil inner cylinder is placed inside the moving coil outer cylinder. The side walls of the moving coil outer cylinder and the moving coil inner cylinder are provided with holes of different sizes. A water guide pipe is connected to the moving coil inner cylinder and the outer cylinder through a sealing O-shaped gasket. A high and low temperature water bath box is connected to the moving coil inner cylinder to build a second constant temperature field. The inside bottom plate of the moving coil inner cylinder is provided with threaded holes for installing a sleeve to fix and clamp a pipe hydrophone with known sensitivity under variable temperature conditions, so as to calibrate the sensitivity of a to-be-tested hydrophone under variable temperature conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater acoustic metrology testing, and particularly relates to a hydrophone low-frequency calibration device under variable temperature conditions. BACKGROUND

[0002] A hydrophone is a sensor device used for underwater detection and capable of converting sound signals into electrical signals. A standard hydrophone is mainly composed of a sensitive element, a support structure, a coating material, and a transmission cable. The sensitive element is capable of converting sound signals into electrical signals of the same frequency. The coating material is generally selected from rubber or polyurethane materials with good sound transmission coefficients. The temperature stability of hydrophone sensitivity is one of the important indicators of the sensor. In order to improve the application of hydrophones in underwater engineering, higher requirements are put forward for the calibration device.

[0003] In the commonly used frequency band, the free field calibration method is usually adopted, which mainly includes contrast method and absolute method. However, in the low frequency band, the vibration liquid column method or the pipe contrast method is usually adopted to calibrate the sensitivity of the hydrophone. The vibration liquid column method is an absolute calibration method for hydrophones. Its advantage is convenient and fast. The sensitivity of the hydrophone to be measured is obtained through a calibrated accelerometer sensor, which is efficient and fast. However, it cannot calibrate large-size hydrophones. The pipe contrast method calculates the sensitivity of the hydrophone to be measured by comparing the sound pressure value of the standard hydrophone with known sensitivity. The operation is simple, but it needs to trace the standard hydrophone, and when the temperature of the hydrophone sensitivity is tested, the temperature has a great influence on the moving coil radiator itself, the measurement uncertainty increases, and it is difficult to accurately calibrate the temperature sensitivity of the hydrophone. SUMMARY

[0004] The present application relates to the technical field of underwater acoustic metrology testing, and particularly relates to a hydrophone low-frequency calibration device under variable temperature conditions.

[0005] Embodiments of the present application can be implemented as follows:

[0006] The present application provides a hydrophone low-frequency calibration device under variable temperature conditions, which is used for calibrating the low-frequency sensitivity of the hydrophone under variable temperature conditions. The device comprises:

[0007] The piston generator, the moving coil outer cylinder, the moving coil inner cylinder and the support bottom plate, wherein,

[0008] The piston generator is magnetically connected with the moving coil outer cylinder and is fixed by a bolt nut for generating a sound signal, forming a stable sound field in the moving coil outer cylinder and the moving coil inner cylinder, and the piston generator is fixed by a bolt through four supporting columns and the supporting bottom plate and is arranged above the supporting bottom plate;

[0009] The moving coil outer cylinder is arranged above the piston generator and is fixed by a bolt with the piston generator for loading the moving coil inner cylinder;

[0010] The moving coil inner cylinder is placed inside the moving coil outer cylinder and is concentrically arranged for establishing a second constant temperature field to realize temperature calibration of the hydrophone.

[0011] The supporting bottom plate is mainly composed of a square plastic plate and four supporting columns and is connected with the piston generator by a bolt for fixing the moving coil outer cylinder device.

[0012] Optionally, the piston generator mainly performs sinusoidal vibration through a piston for generating a stable sound field in the moving coil outer cylinder and the moving coil inner cylinder;

[0013] Optionally, the moving coil outer cylinder further comprises two water guide pipes connected with the moving coil inner cylinder through two conventional holes for guiding water to the moving coil inner cylinder for establishing a second constant temperature field in the moving coil inner cylinder;

[0014] Optionally, the moving coil inner cylinder is provided with a threaded hole at the bottom for placing a sleeve, and the sleeve is used for clamping a standard hydrophone for comparing sound pressure values of a to-be-tested hydrophone.

[0015] As known from the above, the temperature calibration device comprises a square plastic plate as a base, four supporting columns connected with the piston generator, the piston generator generating a stable sound field in the moving coil outer cylinder and the moving coil inner cylinder through sinusoidal vibration of a piston, the piston generator being magnetically connected with the moving coil outer cylinder and being fixed by a bolt, the moving coil inner cylinder being placed inside the moving coil outer cylinder and being connected with the outer cylinder through two water guide pipes for guiding constant temperature water into the moving coil inner cylinder to establish a second constant temperature field in the moving coil inner cylinder for calibrating a to-be-tested hydrophone, and the moving coil inner cylinder is provided with a sleeve at the bottom for fixing a standard cylindrical hydrophone for comparing sound pressure values of the to-be-tested hydrophone, thereby realizing efficient and rapid calibration of the hydrophone.

[0016] Therefore, the application can establish a second constant temperature field in the inner cylinder of the moving coil through two water pipes in the high and low temperature water bath box, and fix the calibrated hydrophone through the sleeve to compare the to-be-tested hydrophone, and through calculating the received voltage values of the two hydrophones, the rapid calibration of the hydrophone can be realized.

[0017] Formula: The sensitivity of the to-be-tested hydrophone can be calculated, wherein M a is the sensitivity of the to-be-tested hydrophone; U a is the open circuit voltage of the output end of the to-be-tested hydrophone; U j is the open circuit voltage of the output end of the circular pipe hydrophone, i.e., the standard hydrophone; M j is the sensitivity value of the circular pipe hydrophone, i.e., the standard hydrophone.

[0018] Compared with the existing calibration device, the application has the beneficial effects that:

[0019] 1. The inner cylinder of the moving coil is connected with the external high and low temperature water bath box through two water pipes, and the outer circulation system of the external equipment can make the water flow in the inner cylinder of the moving coil back to the high and low temperature water bath box, realize the constant temperature keeping of the inner cylinder of the moving coil, establish a second constant temperature field inside the inner cylinder of the moving coil, avoid the quick heat loss in the inner cylinder of the moving coil due to the low ambient temperature, and thus increase the uncertainty of the calibration result; meanwhile, the external equipment is provided with a control valve, which can control the flow of water, so that the sound field inside the inner cylinder of the moving coil is stable and is not affected by the water flow speed.

[0020] 2. The inner side of the inner cylinder of the moving coil is provided with a threaded hole, and different sizes of sleeves can be replaced at will to fix the standard hydrophone. Compared with the conventional calibration method, the open circuit voltage value of the standard hydrophone needs to be replaced, the application can obtain two signals at the same time, i.e., the open circuit voltage values of the standard hydrophone and the to-be-tested hydrophone, prevent the problem that the calibration result error is large due to the quick heat dissipation, and the material of the inner cylinder of the moving coil is selected to be polyurethane material or rubber material with good sound transmission performance, so that the temperature insulation effect is good, and the temperature change inside the outer cylinder of the moving coil due to the heat diffusion has little influence on the piston generator. DETAILED DESCRIPTION

[0021] The accompanying drawings are only used to provide a further understanding of the application, and do not constitute a part of the specification, and are used to explain the application together with the embodiments of the application, and do not constitute a limitation on the application.

[0022] In the drawings:

[0023] Figure 1 is a structure diagram of the calibration device of the hydrophone under the variable temperature condition according to the embodiment of the application.

[0024] Figure 2 Figure 1 is a front view of the hydrophone calibration device under variable temperature conditions according to an embodiment of the present application;

[0025] Figure 3 Figure 2 is an axial side view of the hydrophone calibration device under variable temperature conditions according to an embodiment of the present application;

[0026] Figure 4 Figure 3 is a top view of the hydrophone calibration device under variable temperature conditions according to an embodiment of the present application;

[0027] Figure 5 Figure 4 is a left view of the hydrophone calibration device under variable temperature conditions according to an embodiment of the present application.

[0028] In the figure: 1, moving coil outer cylinder; 2, moving coil inner cylinder; 3, O-shaped sealing coil; 4, water outlet pipe; 5, bolt: GB-T67-2000, M6; 6, nut: GB-T6170_F-2000, M6; 7, piston generator; 8, support column; 9, support bottom plate; 10, bolt: GB-T70, 1-2000, M6; 11, sleeve; 12, standard circular pipe hydrophone; 13, water inlet pipe. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and calibration of the hydrophone under variable temperature conditions of the present application clearer, the specific embodiments of the present application will be further explained in combination with the accompanying drawings.

[0030] In order to make the technical scheme, purpose and advantages of the embodiments of the present application clearer, the accompanying drawings of the embodiments will be described below to facilitate and more intuitively explain the technical scheme of the specific embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Generally, the components described in the drawings can be configured and designed in different sizes.

[0031] Therefore, the embodiments of the present application mentioned in the following drawings are not intended to protect the scope of the present application, but only represent selected specific embodiments of the present application. Any modification, equivalent replacement, improvement, etc. made by ordinary skilled in the art without creative achievement is within the scope of protection of the present application.

[0032] The technical scheme, purpose and advantages of the present application will be described below in combination with the accompanying drawings.

[0033] The embodiment provides a hydrophone low-frequency calibration device under variable temperature conditions, which is used for absolute calibration of sensitivity of a hydrophone under variable temperature conditions, and an external circulation system of a high-low temperature water bath box is connected with a moving coil outer cylinder and a moving coil inner cylinder through two water pipes to establish a second constant temperature field, a sound signal is generated through sinusoidal vibration of a piston generator, and a stable sound field is formed in the moving coil inner cylinder and the moving coil outer cylinder, a sleeve carried in the moving coil inner cylinder is used for fixing a calibrated standard hydrophone, and is used for comparing and calibrating the sensitivity value of a to-be-tested hydrophone under variable temperature conditions. The calibration device can conveniently and quickly complete the variable temperature sensitivity calibration of the to-be-tested hydrophone, and can be widely applied to the low-frequency sensitivity calibration of the hydrophone under variable temperature conditions.

[0034] To achieve the above object, the application provides a hydrophone low-frequency calibration device under variable temperature conditions. Figures 1 to 5 As shown in the figure, a hydrophone low-frequency calibration device under variable temperature conditions comprises:

[0035] The moving coil outer cylinder 1, the moving coil inner cylinder 2, the piston generator 7 and the support bottom plate 9, wherein,

[0036] The support bottom plate 9 is a square plastic plate and is used as a support component of the whole variable temperature calibration system, threaded holes are formed in four corners of the support bottom plate 9 and are used for fixing the variable temperature calibration equipment, the support bottom plate 9 is connected with the piston generator 7 through four support columns 8, the four support columns are through bodies, the support columns are connected through four bolts 10, and the piston generator is fixed;

[0037] Four counter-bore holes are arranged below the support bottom plate 9, which prevent the variable temperature calibration device from tilting due to uneven bottom surface of the support bottom plate, are not conducive to calibration, and are used for fixing the piston generator 7 and the whole variable temperature calibration device;

[0038] The piston generator 7 is arranged above the four support columns and is fixed through the four bolts 10, the piston generator mainly generates a stable sound field in the moving coil outer cylinder 1 and the moving coil inner cylinder 2 through vibration of a piston, the piston generator 7 is mainly connected with the moving coil outer cylinder 1 through magnetism and is provided with four threaded holes, and is rigidly connected through four bolts 5 and four nuts 6 to prevent the moving coil outer cylinder from loosening;

[0039] The moving coil outer cylinder 1 is fixed above the piston generator 7 through rigid connection, and the moving coil outer cylinder is mainly used for loading normal-temperature water and generating a stable sound field under excitation vibration of the piston generator 7;

[0040] The moving coil inner cylinder 2 is made of polyurethane or rubber and the like with good sound transmission coefficient and is placed to the inner side of the moving coil outer cylinder 1, water in the moving coil inner cylinder is variable-temperature water, and a second constant temperature field is established in the moving coil inner cylinder through connection of the two water pipes 4 and 13 with external equipment;

[0041] The water guide pipe 4 is a water outlet, the water guide pipe 13 is a water inlet, an external circulation system of a high and low temperature water bath box is connected, water flows into the inside of the moving coil inner cylinder 2 through the water inlet 13, and flows out to the external circulation system through the water outlet 4, wherein the speed and flow of the water are controlled by a valve;

[0042] The water guide pipe 4, 13 is through the hole, and two O-shaped sealing coils 3 are arranged on the outer side of the water guide pipe 4, 13, so that the water in the inside of the moving coil outer cylinder 1 cannot flow out of the device;

[0043] The bottom of the moving coil inner cylinder 2 is provided with a threaded hole, and the threaded hole is mainly used for fixing a sleeve 11; the sleeve 11 is mainly used for fixing a standard circular pipe hydrophone 12; the circular pipe hydrophone is a calibrated hydrophone, and the sensitivity value of the hydrophone is known under the condition of variable temperature; after the sound signal generated by the piston generator 7 is received by the standard circular pipe hydrophone 12 and the to-be-tested hydrophone, the sensitivity value of the to-be-tested hydrophone is calculated by comparison.

[0044] Therefore, the variable temperature calibration device can establish a second constant temperature field in the moving coil inner cylinder by connecting an external device high and low temperature water bath box, and the water in the moving coil inner cylinder does not need to be replaced back and forth, so that the calibration efficiency is improved; the sleeve 11 is used for fixing the circular pipe hydrophone, so that the variable temperature sensitivity calibration of the to-be-tested hydrophone can be realized without replacing the standard hydrophone, and the variable temperature sensitivity value of the hydrophone can be tested more efficiently and in batches.

[0045] The working principle and use process of the present application are as follows: firstly, a certain amount of water at a certain temperature is obtained by connecting an external device high and low temperature water bath box, the flow is controlled by the water outlet valve of the external circulation system, a second constant temperature field is established in the moving coil inner cylinder, after the temperature is stable, a certain frequency and amplitude sinusoidal signal is emitted by a signal source, the signal is amplified by a power amplifier after impedance matching to excite the piston generator to vibrate, a stable sound field is generated, two-way receiving oscilloscopes are used to collect the open circuit voltage output by the to-be-tested hydrophone and the circular pipe hydrophone, the oscilloscope signals are obtained by an upper computer, and the sensitivity value of the to-be-tested hydrophone at this temperature point can be obtained by calculation and analysis, and the above operation is repeated at the next temperature point to realize the low frequency calibration of the hydrophone under the variable temperature condition.

[0046] Formula: The sensitivity of the to-be-tested hydrophone can be calculated, wherein: M a is the sensitivity of the to-be-tested hydrophone; U a is the open circuit voltage output by the to-be-tested hydrophone; U j is the open circuit voltage output by the circular pipe hydrophone, that is, the standard hydrophone; M j is the sensitivity value of the circular pipe hydrophone, that is, the standard hydrophone.

[0047] Finally, it should be noted that the above merely describes preferred embodiments of the present application and is not intended to limit the present application. Although the embodiments of the present application have been described in detail, those skilled in the art should understand that the modifications to the embodiments of the present application can be made or equivalent replacements to some of the technologies can be made by those skilled in the art with reference to the embodiments of the present application. However, the present application is not limited to this. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low-frequency calibration device for a hydrophone under variable temperature conditions, comprising a moving coil outer cylinder (1), a moving coil inner cylinder (2), a piston generator (7), and a support base plate (9), characterized in that: The supporting base plate (9) is rigidly connected to the supporting columns (8) by four bolts (10). The four supporting columns (8) are connected to the piston generator (7) through four countersunk holes. The piston generator (7) is located above the four supporting columns (8). The moving ring outer cylinder (1) is connected to the piston generator (7) by four bolts (5) and four nuts (6). The moving ring inner cylinder (2) is placed inside the moving ring outer cylinder (1). The sleeve (11) is placed in the threaded hole of the bottom plate inside the moving ring inner cylinder (2). The quasi-circular tube hydrophone (12) is placed in the sleeve; the inner cylinder of the moving coil (2) is connected to the external circulation system of the high and low temperature water bath through the inlet pipe (13) and the outlet pipe (4), respectively. The water flows into the inner cylinder of the moving coil (2) through the inlet pipe (13) and flows out to the external circulation system through the outlet pipe (4). Two O-type sealing coils (3) are provided on the outside of the inlet pipe (13) and the outlet pipe (4). The inlet pipe (13) is connected to the inside and outside of the moving coil through the conventional holes of the outer cylinder of the moving coil (1) and the inner cylinder of the moving coil (2).

2. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 1, characterized in that: The supporting base plate (9) is a square plastic plate with four threaded holes at its four corners and four countersunk holes at the center of the square plastic plate. The four supporting columns (8) connect the piston generator (7) to the supporting base plate (9) through four bolts (10).

3. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 2, characterized in that: The support column (8) has four columns, which correspond one-to-one with the four countersunk holes of the support base plate (9), and the inner hole is a through body.

4. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 1, characterized in that: A threaded hole is located on the bottom plate inside the inner cylinder (2) of the moving coil, which is connected to a cylindrical sleeve (11) that holds a standard round tube hydrophone (12).

5. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 1, characterized in that: The sleeve (11) installed inside the inner cylinder (2) of the moving coil is made of polyurethane or rubber.

6. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 1, characterized in that: The outer diameter of the moving coil outer cylinder (1) is 136mm, the inner diameter is 120mm, the wall thickness is 8mm, and the height is 240mm. The side wall hole diameter of the moving coil outer cylinder (1) is 10mm.

7. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 1, characterized in that: The outer diameter of the moving inner cylinder (2) is 100mm, the wall thickness is 5mm, and the height is 185mm; the side wall hole diameter of the moving inner cylinder (2) is 8mm, and the threaded hole diameter of the inner bottom plate of the moving inner cylinder (2) is 4mm and the depth is 4mm.

8. The hydrophone low-frequency calibration device under variable temperature conditions according to claim 1, characterized in that: The sleeve (11) has an outer diameter of 18mm and an inner diameter of 14.1mm. The standard round tube hydrophone (12) has an outer diameter of 14mm. The bottom of the sleeve (11) is provided with a cylinder with an outer diameter of 4mm that is connected to the bottom of the moving coil inner cylinder (2).

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