SU1314235A1 - Method and apparatus for measuring sound velocity - Google Patents

Abstract

This invention relates to a measurement technique. The aim of the invention is to increase accuracy and resolution. In a device that implements a speed measurement method, measurement unit 1 produces an electrical impulse that excites a reversible electroacoustic transducer 2. Acoustic oscillations, propagating from reversible transducer 2, form a converging wave. After passing the focus, the sound wave diverges and reaches the enclosed surface of the reflector 3, from which it is reflected back, converge again into focus, passing in the opposite direction, hits the reversible electroacoustic converter 2, where it is converted into an electrical signal and is recorded in the block 1, in which the speed of sound propagation is determined. 2 sec. f-ly, 2 ill. (Lf (/v./

Description

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This invention relates to a measurement technique and can be used to measure the speed of ultrasound;

The aim of the invention is to improve the accuracy of resolution by forming a convergence of wave fronts.

FIG. 1 shows a device implementing a method for measuring the speed of sound; in fig. 2 is a device concentration function.

A device that implements the method of measuring the speed of sound contains a series-connected measurement unit 1 and a reversible electroacoustic transducer 2 and a sound reflector 3. The surfaces of the electroacoustic transducer 2 and the sound reflector 3 are made in the form of parts of a sphere with R and Rg

the curvatures with the same angles O 0 are open, the axes of which are located on the same straight line and facing each other with concave surfaces.

Provides for the location of the Converter 2 and the reflector 3 in a controlled environment 4.

A device realizing a method for measuring the speed of sound works as follows.

Measurement unit 1 generates an electrical impulse that excites a reversible electroacoustic transducer 2. The latter converts electrical oscillations into mechanical ones, which, propagating in a controlled medium 4 from the radiating spherical surface of reversible transducer 2, form a converging acoustic wave. After passing the focus, the sound wave diverges and reaches the enveloped surface of the sound reflector 3, from which the sound wave is reflected back, converging again to the focus, which passed in the opposite direction, falls on the reversible electroacoustic converter 2, 1 de converted into electrically Low and reg isterred in measurement unit 1, in which the velocity of sound is determined.

The function F (x) of the concentration of the device (Fig. 2) is equal to the ratio of the initial area of the front of the sound wave to the area of the front of the sound wave

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at a distance x. With distance from the radiating surface of the reversible converter, the 2 functions F (x) of the concentration increases, reaching its maximum value in the focal plane, which makes it possible to measure the sound velocity in small inhomogeneities.

Example. An electronic circuit of a pulse-cyclic velocity meter and an acoustic focusing system with parameters R R 2+ R 1 cm were used; L R / + 2cm; In 1cm. At the same time, a reversible electroacoustic transducer. 2 is made of piezoelectric ceramics of the PZT-19 type, polarized in thickness. Electrodes are deposited, for example, by metallization on the convex and concave surfaces of piezoceramics. The internal electrode is grounded. The external electrode is acoustically and electrically isolated from the environment. If the electronic circuit starts20

 is the first reflected pulse (p 1), then the pulse frequency at the output of the electronic circuit f C / 2L C / 4R, g de c is the speed of sound, from where 4Rf. When R 1 cm

 and from 1.5 km / s, f 37.5 kHz. If the duration of the emitted sound impulse is 10 s, then its sp o spacation / I in a liquid is L 7 7 o, 15 mm, diameter

The 35 d focal spot will be d 1.22 X A L / D 0.4 mm.

Concentration factor for the specified parameters in the focal plane F (0) (D / d) 600, What can investigate the inhomogeneities of the field of the speed of sound up to g 0.4 mm.

In the proposed device instead of the reflector you can use

5 second electroacoustic transducer, analogous to the first, connected to unit 1 of measurements.

Claims (2)

Claim 50 1. A method for measuring the speed of sound, which consists in emitting a pulse of acoustic oscillations into a controlled medium, receiving a reflected signal, measuring its time 55 the arrival, according to which, taking into account the size of the measurement base, the desired parameter is defined, characterized in that, in order to increase the accuracy and resolution, radiation and reflection form converging wave fronts, whose curvature centers are located on the measurement base, and the measurement base is not - suppresses the radius of curvature of wave fronts. 2. A device for measuring the speed of sound, containing a series-connected measurement unit and a reversible electroacoustic transducer and sound reflector, characterized in that, in order to increase the accuracy of the resolution, the surface of the electroacoustic transducer and sound reflector are made as parts of a sphere with the same opening angles, the axes of which located on the same straight line and facing each other with concave surfaces. (Reg. 2 Compiled by G. Ryzhakov Editor A. Lezhnin Tehred V. Kadar Proofreader A.T. Order 2206/44 Circulation 500 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company Uzhgorod, st. Project, 4