Device for determining the acoustic parameters of the receivers of the pressure gradient

 

The invention relates to a measurement technique, namely the measurement of parameters of piezoelectric transducers. The technical result - the simplification of the device, the extension of the frequency range defined parameters in the direction of low frequencies without increasing the size of the device, providing the possibility of determining the parameters of the receivers of the pressure gradient with a low threshold in any environment, including in the water. The device has low noise, easily realizable in the computer system. Device for determining the acoustic parameters of the receivers of the pressure gradient contains a rigid pipe, the first end of which is mounted a first emitter, electrically connected to the signal generator. Inside the pipe is installed the test receiver pressure gradient and the first measuring pressure receiver, electrically connected respectively with the first and second input switch, the output of which is connected to the input of recording equipment. The rigid tube is closed at its second end has a second emitter, identical to the first, is connected to the signal generator through the phase shifter. In the Central part jesd the cross section of which is tightly and rigidly fastened along the contour of the inner surface of the sleeve bimorph bending sensor element. When the metallic sleeve is a wall of the Central part of the rigid pipe, and the device entered the second measuring pressure receiver, identical to the first set with him coaxially and symmetrically on opposite sides of the test receiver pressure gradient and electrically connected to the third input of the switch. 1 C.p. f-crystals, 3 ill.

The invention relates to a measurement technique, namely the measurement of parameters of piezoelectric transducers.

Acoustic receivers pressure gradient are quite small and yet have the focus, which makes them particularly attractive for solving a number of tasks directional reception at low frequencies.

One of the most common types of receivers, the pressure gradient is the receiver of the pressure gradient, made in the form of bending bimorph sensing element which is a thin metal disc, which is glued piezo disk, fixed on the contour to a massive sleeve (FCB) [1, S. 314-316]. The application solves the problem of determining the parameters of the receivers of the pressure gradient this construca and metrological characteristics in particular, the frequency response of the sensitivity and directivity, which characterize the receiver and its scope. Characteristics required to determine, periodically, to confirm, check them out depending on the term and conditions.

A device that provides a measurement of the frequency characteristics of sensitivity and directional acoustic receivers, pressure gradient, built on the principle of direct comparison with the exemplary receiver pressure in “free-field”, and only if both of the receiver affects the true plane wave.

Such a device comprises a generator, electrically coupled to the emitter, turning the device on which you installed the exemplary omnidirectional receiver pressure and the test receiver pressure gradient, is connected through a switch to registering devices [1, C. 85].

The same device provides the definition of the pattern and characteristics of sensitivity in the near zone “free field”.

However, the difficulties of measurement in the far and near zones are mainly associated with the challenges of ensuring the conditions of “free field” and so is x devices for rotating converters in different planes [1, S. 89].

It is known device, devoid of the limitations associated with the measurement in the “free field”, based on the use of pipes Bauer with standing wave. The device is a closed segment of a tube with rigid walls, which are suspended on soft suspension and varies entirely located in the pipe fluid and the test receiver pressure gradient. At the end of the pipe has an accelerometer. The fluid within the pipe segment, moves as a small plot of system with standing wave and has a very specific distribution of pressure amplitude and oscillation speed. If we measure the vibrational speed of the pipe ends using the accelerometer, the oscillation velocity and pressure at any point of the closed pipe can be calculated, and then, knowing the open-circuit voltage from the output of the receiver pressure gradient to calculate its sensitivity [2, S. 184].

However, this device is complicated in technical execution, because it requires the creation of a harmonic generator of mechanical vibrations, suspensions, allows operation only with the inertial environment (water) and provides only discrete building pattern associated with posledovat similar set of features of the present invention is a device described in [2, C. 182]. The device is open at one end with a vertical tube at the closed end of which has an emitter connected to the input of the signal generator. In the inner cavity of the pipe installed measuring omnidirectional receiver pressure and the test receiver pressure gradient is fixed on the rotary device. The outputs of the measuring receiver pressure and the test receiver pressure gradient across the switch is connected with the input of the recording equipment. The pipe is filled with water.

Standing waves, excited by the emitter in the liquid column between the emitter and the reflecting surface water-to-air impinges on the receiver pressure gradient and measuring the pressure receiver. Stress values with these receivers come to registration apparatus, and calculates the sensitivity of the test receiver pressure gradient pressure. The directivity of the receiver pressure gradient is logged when the rotation shaft of the rotary device from 0° up to 360°.

The disadvantage of this device is the limited application due to the need of use environments, providing at the interface imped is th at low frequencies, a low level of sound pressure that is required to define the parameters of the receivers of the pressure gradient with a low threshold, the creation of mechanical devices for rotation in a given plane and with sufficient accuracy. The device provides in a vertical position only.

The objective of the invention is to provide an effective acoustic device for determining parameters FCB, devoid of the drawbacks of the prototype.

Technical results of the claimed invention is the simplification of the device, the extension of the frequency range defined parameters in the direction of low frequencies without increasing the size of the device, providing the possibility of determining the parameters FCB with a low threshold in any environment, including water, has a low noise level, easily realizable in the computer system.

To achieve the said technical result in the device for determining the acoustic parameters of the receivers of the pressure gradient, containing a rigid pipe, the first end of which is mounted a first emitter, electrically connected to the signal generator, and inside the pipe is installed the test receiver gladiatorum input switch, the output of which is connected to the input recording equipment, introduced new features, namely: a rigid tube is closed at its second end has a second emitter, identical to the first, is connected to the signal generator through the barrier in the Central part of the rigid pipe is installed the test receiver pressure gradient, consisting of a metal sleeve, cross-section which is installed tightly and rigidly fastened along the contour of the inner surface of the sleeve bimorph bending sensor element, when the metallic sleeve is a wall of the Central part of the rigid pipe, and the device entered the second measuring pressure receiver, identical to the first, mounted coaxially with him and symmetrically on opposite sides of the test receiver pressure gradient and electrically connected to the third input of the switch.

The construction of the claimed device is simplified, and the efficiency is increased if the first and second receivers pressure is made in the form of a cylindrical piezoceramic transducers, forming symmetrical with respect to the test receiver pressure gradient sections of rigid pipe.

Explain Costigan the GB, located at a distance sleeve lengthx apply pressure, the difference due to the phase shiftx (pressure gradient), leads to the fact that the diaphragm and the piezoelectric disc sags, and voltage at the output of the piezoceramic disk will be expressed by the formula

where- circular frequency, C is the speed of sound in the environment,the angular position of the receiver pressure gradient to the source, the P - value of sound pressure, Mx(t) is the sensitivity of the FCB to the pressure, f is the frequency.

The expression (/x cos) is the phase shift in a flat wave (phase delay) at a distance ofx and an element of the irregular pattern of expression (1), in which the voltage at the output FCB depends on the phase difference of pressure acting on the acoustic inputs receiver pressure gradient, a certain angular position of the receiver on the source of the sound. It follows that if you create a device that will provide Agostino angle FCB, the recording equipment shall record the output FCB voltage e, which is irregular pattern obtained without actual rotation around the axis perpendicular to the generatrix of FCB. To implement this method, it is proposed to use a closed segment of a tube with emitters on the ends and FCB in the center of this tube, dividing the volume of this pipe bending in two sensitive bimorph element. Each of the emitters organizes resulting in the camera sound pressure and phase shift of one relative to another will be determined by the phase shifter, connected in series with one of the emitters. When changing the phase delay in the range from 0 to (/x cos) continuously or discretely, you can get the pattern without the use of a rotary device.

While measuring receivers pressure fix the sound pressure in the pipe, and average the two readings of the voltage eswill be proportional to

Comparing the values of eSfor=0 and e, from expressions (1) and (2) will get the value of the f) - the dependence of the sensitivity on the frequency of the measuring receiver pressure.

Thus, the frequency response of the sensitivity and directivity FCB may be obtained in the proposed device without the use of mechanical rotary device. When measuring in the air provided a low impedance across the volume of the chamber, so the receiver of the pressure gradient with a relatively low impedance does not violate the homogeneity of the pressure in each half of the camera saves phase pressure ratio and is a measure of the directivity and sensitivity of the test receiver. The pipe is made rigid, and the drivers are mounted on two end surfaces of the pipe, which results in high pressure created by the emitters and perceived FCB. Measurement in more dense environments (e.g., water) is possible, but requires some design requirements calibrated receivers or will increase the accuracy of the measurements.

The invention is shown in Fig.1, 2, 3, where Fig.1 shows a block diagram of the proposed device of Fig.2 is a diagram of the orientation of the FCB received on the proposed device of Fig.3 pravlenie the device is a rigid closed pipe 1, at the ends of which includes first and second identical emitters 2, 3. The Central part of the pipe is formed by a metal sleeve 4 FCB 5. In the Central section of the sleeve is installed tightly and rigidly fastened along the contour of the inner surface of the sleeve bimorph bending sensor element made in the form of a thin metal disk 6, to which is glued supository the thickness of a thin disc of piezoelectric ceramics 7. To both end surfaces of the metal sleeve, is symmetrical about its Central cross section, the ends of the connecting sleeve 8, 9, attached two piezoceramic cylinder 10, 11, the outer diameter of which is equal to the diameter of the metal sleeve. Piezoelectric cylinders supository in the direction of the radius and function of receiver pressure. In another execution of omnidirectional receivers pressure can be replaced, for example, omnidirectional hydrophones. The emitter 2 is electrically connected to the output of the generator 12, and the emitter 3 - the output of the phase shifter 13, the input connected to the output of the generator 12. The outputs of the measuring receiver pressure 10, 11 and the output of receiver pressure gradient 5 electrically connected with the switch weusa equipment were used appliances company Brual & Kjar, 2010 analyzer and recorder 2307, was also used generator G-103, radiators served as the dynamics of 0.5 GDS - 15. The rotating shaft of the phase shifter was connected mechanically with the drive recorder.

Measurement parameters FCB using the proposed device is as follows. Using the known values, andx determine the maximum value of phase delay

=(/(C)X.

set as the limit on the phase shifter 13.

To determine the pattern set Phaser to zero, include the signal generator 12 and register the adopted measuring receivers, the signal level of the recording apparatus 15. Switch switch to to registering devices was connected FCB. Changing the angle of the phase delay in the range from 0 to (/x cos), wherevirtual angle FCB around its axis, make you check the data readings output FCB emaxaccording to the testimony of recording equipment, then flip the switch and record the reading esthe output of the measuring receiver pressure 9, 10. Changing the frequency of repeat measurements. Determine the frequency response of the receiver sensitivity of the pressure gradient Mx(f) no the formula (3).

Describes the measurement algorithm is easy to implement on computers and low frequencies and unlimited time measurement does not cause difficulties with the technical implementation. The proposed device can be used as test equipment, and as a means of measurements after appropriate procedures for certification or verification.

The proposed device has been manufactured, tested and is currently used in studies of FCB. In Fig.2 and 3 present, respectively, the directional diagram of the FCB, taken at a frequency of 100 Hz during virtual rotation FCB=0°-540°, and the calculated sensitivity pressure Mx(f) in the range of the real phase shifts atx=20,0 mm pipe Sizes (without FCB) do not exceed 120.0 mm and a diameter of 35.0 mm Installation allows you to produce and the enta pressure 0.1-1000,0 µv/PA, that allows us to consider the objective of the invention is resolved.

Sources of information

1. R. Bobber. “Hydroacoustic measurements M., Mir, 1974.

2. G. K. Skrebnev. “Combined hydroacoustic receivers”. SPb., 1997.

Claims

1. Device for determining the acoustic parameters of the receivers of the pressure gradient, containing a rigid pipe, the first end of which is mounted a first emitter, electrically connected to the signal generator, and inside the pipe is installed the test receiver pressure gradient and the first measuring pressure receiver, electrically connected respectively with the first and second inputs of the switch, the output of which is connected to the input of the recording apparatus, characterized in that the rigid tube is closed at its second end has a second emitter, identical to the first, is connected to the signal generator through the barrier in the Central part of the rigid pipe is installed the test receiver pressure gradient, consisting of a metal sleeve, cross-section which is installed tightly and rigidly fastened along the contour of the inner surface of the sleeve bimorph bending sensitivity is the device entered the second measuring receiver pressure, identical to the first set with him coaxially and symmetrically on opposite sides of the test receiver pressure gradient and electrically connected to the third input of the switch.

2. The device under item 1, characterized in that the first and second receivers pressure is made in the form of a cylindrical piezoceramic transducers, forming symmetrical with respect to the test receiver pressure gradient sections of rigid pipe.



 

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