SU1585690A1 - Apparatus for measuring speed of propagation of ultrasound in liquids - Google Patents

Abstract

The invention relates to a measurement technique and can be used, in particular, in determining the density distribution over the volume of a liquid under study and studying the kinetics of chemical reactions. The purpose of the invention is to expand the functionality by making it possible to determine the distribution of ultrasound velocity values. The device includes a fan-interdigitated transducer (IDT), which radiates an acoustic signal with a spectrum width smaller than the frequency interval between the waveguide modes formed by two parallel piezo-substrates, between which the test fluid is placed. Scanning of the volume under study occurs when the modulation frequency of the signal applied to the emitting IDT is changed. 1 il.

Description

The invention relates to a measurement technique and can be used, in particular, in determining the density distribution in solutions and studying the kinetics of chemical reactions.

The purpose of the invention is to expand the functionality by making it possible to determine the distribution of the velocity of ultrasound from the volume of the liquid.

The drawing shows a block diagram of the device.

A device for measuring the speed of propagation of ultrasound in liquids contains two flat parallel piezo-substrates 1 and 2 applied

on a piezo-substrate 2 radiating fan 3 and receiving 4 interdigital transducers (IDT), a generator of 5 pulses, a series-oscillating frequency generator 6 and a modulator 7, the second input of which is connected to the output of the generator of 5 pulses, and connected to the output of the receiving ICS 4 the time measurement unit, made in the form of a frequency meter 8, the input of the radiating IDT 3 is connected to the output of the modulator 7.

The device works as follows.

The investigated liquid is placed between two flat parallel piezo-substrate 1 and 2, which are formed

30 SP

with

sound acoustic waveguide. The oscillating frequency generator 6 generates an electrically sinusoidal signal with a time variable frequency. The signal is applied to the modulator 7, to the control input of which a broadband electric pulse is simultaneously supplied from the generator of 5 pulses. On the modulator 7, an amplitude-pulse modulation of a sinusoidal signal occurs, resulting in a radio pulse with a spectrum bandwidth smaller than the interval between the waveguide modes, which is fed to the radiating transducer 3, made in the form of a fan transducer, in which the spatial variation between the pins along the normal to the acoustic channel. When a broadband electric signal is applied to the transmitting IDT 3, surface waves are excited, which excite the volume waves in the acoustic waveguide only at a certain angle (Rayleigh), and, accordingly, only those normal modes, the phase velocities of which are equal to Rayleigh Vp, t . The transducer – acoustic waveguide system automatically automatically selects from the signal spectrum only those components that are capable of exciting normal modes with phase velocities equal to Rayleigh. At the receiving IDT 4, a signal with a periodic spectrum corresponding to a periodic pulse sequence with a time interval between the lows is obtained, which is measured with the help of block 8 (-frequency meter) from 1 time measurement as iC tt.

Where

uf - the difference between adjacent modes, According to the formula

,

four

Vp

i

i +

(UHt): 2H

where H is the acoustic base, determine the speed of propagation of ultrasonic waves in section y ,. Then, the oscillating frequency generator 6 changes the frequency of the sinusoidal signal by changing the frequency of filling the radio pulse.

Thus, sequentially changing the frequency of the sinusoidal signal, determine the speed of ultrasonic waves in different sections

Claims (1)

the investigated volume V ,,., y,, Formula invented Vzhuu n and A device for measuring the speed of ultrasound propagation in liquids, containing a pulse generator, first and second flat parallel piezo substrates deposited on one of the piezo substrates, emitting and receiving anti-pin transducers and a time measuring unit, the input of which is connected to the output of the receiving anti-pin transducer, This is so because, with the aim of expanding and functional capabilities due to the possibility of measuring the distribution of the velocity of ultrasound over the volume of the studied liquids, it is equipped with series-oscillating frequency generator and modulator, the output of which is connected to the input of the radiating interdigital transducer, the second input of the modulator is connected to the output of the pulse generator, the time measuring unit is made in the form of a frequency meter, and the radiating counter-pin the converter is made in the form of a fan converter .-