SU1499216A1 - Method of measuring the speed of propagation and coefficient of absorption of acoustic vibrations - Google Patents

Abstract

The invention relates to acoustic measurements and can be used in studies of the physical parameters of substances and materials and in the control of technological processes. The purpose of the invention is to enhance the functionality by making it possible to measure the product of the modules of the reflection coefficients and to increase the accuracy of the measurement of the absorption coefficient of acoustic oscillations. The values of the frequency deviation of the oscillations passed through the medium under study are measured with two values of the acoustic base of measurements at the carrier frequency of the frequency-modulated signal corresponding to one of the local maxima of the steepness of the phase-frequency characteristic of the measuring chamber.

Description

The invention relates to acoustic measurements and can be used to study substances and materials using acoustic measurement chambers.

The purpose of the invention is to expand the functionality by making it possible to determine the product of the moduli of the reflection coefficients of acoustic vibrations and increase the accuracy of measurements of the absorption coefficient of acoustic vibrations,

The method is carried out as follows.

Acoustic oscillations modulated in frequency according to the harmonic law emit into the measuring chamber of variable length and receive the measurements that pass through the measuring chamber.

oscillations with the test substance Change the carrier frequency of the emitted oscillations and determine two values of f and the carrier frequency corresponding to the local deviation maxima and the frequency of received oscillations at the acoustic base L ,. Measure the dBO value, the frequency deviation of the received oscillations at one of the determined carrier frequencies f or

f "Then change the length of the measurement + to

tel camera to the value of L corresponding to the maximum deviation of ACOj. frequency of oscillations at

four:

WITH

with

N)

O5

carrier frequency ff, or f are measured

 Of the propagation velocity V, the coefficient of subsidence (en and the product g of the moduli of reflection coefficients

acoustic oscillations are determined by the formulas

V

b (Hz)

 k

g exp

G L, jlnCt, b, 1pfg 1

L J.

I - l g

rmt-td - (;,; where q;

Tco-Tso about

(& Sv-deviaci

frequency of emitted oscillations; 0 (for L у and (q, jHACO ACOg РИ L L ,,); n and k are integers.

1A992I6. four

oscillations that take into account the propagation velocity and the absorption coefficient of acoustic vibrations, characterized in that, in order to enhance the functionality by making it possible to determine the product of the modules of the reflection coefficients of acoustic oscillations and to improve the accuracy of determining the absorption coefficient of acoustic oscillations, change the modulation frequency and acoustic base of measurements to values corresponding to the maximum deviation of the frequency of received oscillations on one of specific carrier frequencies radiated oscillations measured deviation UGDiz oscillation frequency of the received value and

ten

15

20 -"

B is the acoustic measurement base, and the absorption coefficient uf of the acoustic oscillations and the product g of the moduli of the reflection coefficients of acoustic oscillations from the emitter and receiver are determined by the formulas

Claims (1)

Invention Formula The method of measuring the propagation velocity and the absorption coefficient of acoustic oscillations, which consists in emitting frequency-modulated acoustic oscillations using an emitter, picking up the oscillator after passing through the medium by the receiver, changing the carrier frequency of the emitted oscillations There are two maxima of the frequency deviation at the acoustic base, the measurement of the SRI L (, the values of the carrier frequency corresponding to the maxima of the deviation of the frequency of the received oscillations are measured, and ation du | frequency to prinig 20 -" 25 thirty 35 40 B is the acoustic measurement base, and the absorption coefficient uf of the acoustic oscillations and the product g of the moduli of the reflection coefficients of acoustic oscillations from the emitter and receiver are determined by the formulas  . In L b) (y, j G, - L, ln ( r exp -i -: rJ --- 12:, L b - UW, + DSOO -D-, -TY -TsoG-. SOA + LSOO. 2 LSOD - deviation frequency of received oscillations Compiled by D 11 Irochin Editor and Gorna Techred M. DidykKorrektor L Patay Order 4683/41 Circulation 789 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Subscription