SU1504606A1 - Ultrasonic device for measuring physiocal parameters of substances - Google Patents

Abstract

This invention relates to acoustic non-destructive testing. The aim of the invention is to expand the field of application and increase sensitivity due to the possibility of working with hot substances with a high signal-to-noise ratio due to the measurement of the reflection coefficient of longitudinal ultrasonic (US) vibrations and the choice of materials and dimensions of the sound guide and piezoplates in a special way. Piezoplastina 1 excites in the solid duct 3 pulses of longitudinal ultrasonic vibrations and receives normally reflected echo pulses by the surface 12, bordering on air, and surface 11, bordering on the test substance 18. According to the ratio of the amplitudes of these echo pulses, reflected by surfaces equal in area 11 and 12, determine the right-angle reflection coefficient. The piezoplate 2 excites in the duct 3 longitudinal ultrasonic vibration pulses that propagate at an indirect angle to surfaces 11 and 12 and feed after reflection on piezoplate 1 at an angle such that the zero mode of the Lamb wave is excited in it. By the ratio of the amplitudes of these reflected pulses, the reflection coefficient is determined at an indirect angle, and the physical parameters of the substance are determined using the coefficients found. 2 Il.

Description

fi

3150

The invention relates to acoustic non-destructive testing and can be used to measure the physical parameters of substances, such as liquid or gaseous substances.

The aim of the invention is to expand the field of application due to v enabling the device to work in contact with hot substances and increasing sensitivity due to the use of longitudinal ultrasonic (US) vibrations that excite the Lamb wave in the receiving piezoplate, resulting in a high signal ratio. cash / noise

FIG. 1 shows a diagram of the device; in fig. 2 is a view A of FIG. one.

An ultrasonic device for measuring the physical parameters of substances contains the first and second piezoplates 1 and 2, respectively, a solid duct 3 and a generator A of pulses associated with piezoplates 1 and 2. The ultrasound device also contains connected in series to the first piezoplate 1 a first pulse selector 5, a first amplifier 6, and a first voltage ratio meter 7. The second input of the first voltage ratio meter 7 is connected to the second output of the first pulse selector 5. In addition, the ultrasonic device contains devices connected to the first piezoplate 1 in series by the second pulse selector 8, the second amplifier 9 and the second meter 10 of the voltage ratio. The second input of the second voltage ratio meter 10 is connected to the second output of the second pulse selector 8. The solid duct 3 is made with two different-height reflective parallel surfaces 11 and 12 and connecting these surfaces perpendicular to them plane 13. The first piezoplate 1 is installed on the surface of the sound duct 3 parallel to its reflecting surfaces 11 and 12. The second piezoplate is mounted on the sound surface coprode 3 at an angle about the reflecting surfaces 11 and 12. The connecting plane 13 passes through the acoustic axes of piezoplates 1 and 2. The acoustic axis of the second piezoplates 2 is directed toward the piezoplates 1. The area of the reflecting surface 11, distant with respect to piezoplates 1 and 2, is equal to the area of the reflecting surface 12, which is near to piezoplates 1 and 2. Piezoplates 1 and 2 are set so that the distances X x from the projection of the centers of the corresponding plates 1 and 2 to the far reflecting surface 11 to the top of the coal (formed by the mounting plane of the second piezoplate 2 and the reflecting surface 11, satisfy condition X, (X + S sin 66cosci) / cos2od, (1)

where S is the distance from the installation plane of the first piezoplate 1 to the reflecting surface 11,

The dimensions d and d of piezoplates 1 and 2 in the plane coinciding with the connecting plane 13 satisfy the condition

d b d / cosui.

(2)

The value of the angle about is determined from the equality

oi arcsin (, (3)

where Cj is the velocity of propagation of longitudinal ultrasonic oscillations in the material of the suction line 3; Cg is the phase velocity of the zero mode of the Lamb waves in the first piezoplate 1.

The material of the sound duct 3 is chosen in such a way that the condition

C C,

(BUT)

No3HUHHNrrf 14-17 designates ultrasonic vibrations of different directions of propagation in the duct 3, and position 18 is the test substance.

An ultrasonic device for measuring physical parehmeters of substances works as follows

Piezoplates 1 and 2 are made, for example, from PZT-19 material at a frequency of 6 MHz (Sd 2365 m / s). To satisfy the condition (4), the duct 3 is made, for example, of fluoroplastic (C 1348 m / s). Based on condition (3), the angle ui is chosen to be equal. When working with piezoplate 2, for example, with a diameter of d 30 mm, in accordance with condition (2), it is necessary to choose diameter d, piezoplates 1

more than or equal to 36.5 mm. During the measurements, the device with the surface 1 of the chimney 3 is in contact with the test substance 18. The generator 4 of the pulses simultaneously excites the piezoplates 1 and 2.

Piezoplastina 1 radiates into the sound conductor 3 pulses of longitudinal ultrasonic vibrations 14 and 15. Reflected from the surface 12 of the acoustic duct 3 bordering on the air, and parts of the longitudinal oscillations 14 and reflected from the surface 11 of the acoustic conductor 3 adjacent to the substance 18, longitudinal pulses oscillations 15 are returned to the piezo plate 1 and are transformed by it into electrical signals that are fed to the input of the selector 5. At the first output of the selector 5, the pulse generated by the oscillations 16 is generated and through the amplifier 6 is fed to the numeral input of the meter 7 . N the second output of the selector 5 is released pulse generated kolebat-1 E 14, and supplied to a remarkable WMOs meter 7. The gain of the amplifier 6 previously adjusted so that in the absence of the substance 18 pulse amplitudes fed to the inputs of the meter 7, bshi equal. In this case, the readings of the meter 7 ratio of the stresses at the acoustic contact of the chimney Z. with the substance 18 are equal to the coefficient V of the reflection of the longitudinal ultrasonic oscillations of the pa, which is normal to the boundary of the material of the sump 3, the test substance 18,

Piezoplastina 2 also emits pulses of longitudinal ultrasonic vibrations in

46066

the acoustic duct 3, which fall on the surface- 11 and 13 at an angle c, reflects and falls the piezoelectric plate 1, 2 excites the Lamb wave in it

fashion The pulses of the longitudinal oscillations b are reflected from the near surface 12, and the pulses of the longitudinal oscillations 17 from the far surface 11.

10 Excited reflected oscillations — Bolzn Lzmba are transformed by piezo plate 1 into electrical signals that are fed to the input of selector 8. At the first output of selector 8, a pulse is produced by oscillations 17j and through amplifying 9 is fed to the numeral input of meter 10. At the second output of the selector 5 takes up the pulse created by oscillations 16 and is fed to the significant input of the meter 10. The gain of the amplifier 9 is preset such that, in the absence of substance 18, the amplitude and myles

The 25 supplied to the inputs of the meter 10, are equal. In this indication, the voltage ratio meter 10 at the acoustic contact of the sound guide 3 with the substance 18 is equal to the reflection coefficient of the longitudinal ultrasonic vibrations. at an angle ot to the boundary, the material of the sound duct 3 is the test substance 18.

35

From the found values of the reflection coefficients Vg and V, the speed C of propagation of longitudinal ultrasonic vibrations in the test substance 18, its density p and its coefficient

 Cent I I adiabatic compressibility

- out of the following forms:

C - CijilI YiliLb (l ± YbaO :: V) li; Pi ciH-bV2.) I (i; v;

(1 -V,) b (1 + V) -a (1 -V) S inc

n - P lI- -yo Ib (HV) -a ()

R .. .- ...

r

 (1 -V,) 2 b (1 + V) -a (1 -V) 2p 2 c | (t + V) 2 (1 -V) 2 () (1 + V) -a (1-V) lsinoL

 Cl P (I + VO) l | (1-Y,) (HU) -a (1-Y) 2p C | (1 + Vj4l-Vf where a 4p, C | sin si lc -C. Bp, (C2 -2C2 51pY) (NW

p, is the density of the material Zvukovaya 3; , is the speed of propagation of transverse ultrasonic vibrations in the material of the sound duct 3.

The use of longitudinal ultrasonic vibrations in measurements, which have a smaller absorption coefficient relative to transverse ultrasonic vibrations, makes it possible to use a sound conduit of a larger size and of such a shape on the outer side so that it is possible to cool piezoplates when measuring parameters of substances found under high temperature conditions. Keeping the temperature of the sound duct in the zone of the installation of piezoplates, ensure the constancy of the angle of incidence on the first piezo plate, in which the Lamb waves are excited. In the section of the sound duct under conditions of a gradual increase in temperature, the direction of the wave beam changes, but after reflection on the reflecting surfaces when it returns in the opposite direction, this change in direction of propagation occurs in such a way that the same wave beam arrives at the first piezoplate hzb angle at which lamb waves are excited. In this case, a wave beam shifts and, therefore, under conditions of high temperature differences, it is necessary to use a piezoelectric plate of large dimensions.

Claims (1)

Invention Formula An ultrasonic device for measuring the physical parameters of substances, containing two piezoplates, a solid acoustic conductor with two differences. reflective parallel surfaces, a pulse generator connected to piezoplates connected to the first piezoplate, serially connected first pulse selector, amplifier and voltage ratio meter, the second input of which is connected to the second output of the first pulse selector, and serially connected second selector pulse, amplifier and voltage ratio meter, the second input of which is connected to the second about five , The second selector, the first piezoplate, is installed on the duct surface parallel to its reflecting; 11 to them surfaces, the plane connecting the reflecting surfaces is perpendicular to them and passes through the acoustic axis of the first piezoplate, which is designed to expand the field of application and increase sensitivity The second piezoplate is installed on the surface of the acoustic duct with the angle oi to the reflecting surfaces so that its acoustic axis is directed B to the side of the first piezoplate and lies in the plane, soy yn guide reflective surfaces plosh, adi reflecting surfaces are equal, and the materials and geometrical dimensions and acoustic conductor selected from the piezoceramic plates conditions about arcsin (Cg / Co); From 0 di d / cosoi; X, (S 8ine6 cosciiy / cios b6, where C. is the propagation speed longitudinal oscillations in the duct material; С phase velocity of the zero mode of Lamb waves in the first piezoplate; d, is the size of the first piezoplate in connection to the plane reflecting the common surfaces of the plane; d is the size of the second piezoplate in the plane connecting the reflecting surfaces; X - distance from the top of the corner d, for projecting the center of the first piezoplate to the far reflecting surface; X is the distance from the top of the angle oido of the projection of the center of the second piezoplate to the far reflecting surface; S is the distance from the installation plane of the first piezoplate to the far reflecting surface. Fi & .2