SU1642366A1 - Method of determination of ultrasound velocity in medium with variable parameters - Google Patents

Abstract

The invention relates to ultrasonic non-destructive testing methods and can be used to measure dynamic parameters and% control processes occurring in an environment with variable parameters. The purpose of the invention is to increase the information content by determining the absolute value of the velocity of ultrasound in a controlled environment. Continuous sinusoidal oscillations of a constant frequency, which are received by another piezoelectric transducer, are sent to the studied medium with time-varying parameters of the ultrasonic piezoelectric transducer, the frequency change is recorded at two time points after a certain interval, and the absolute value ultrasound speed about 1 Il. g C /

Description

The invention relates to ultrasonic non-destructive testing methods and can be used to measure the dynamic parameters of processes taking place in the test medium by measuring the soundness of the sound in it,

The aim of the invention is to increase the information content by determining the absolute value of the velocity of ultrasound in a controlled environment with varying parameters.

The drawing shows a block diagram of a device for implementing the method.

The device consists of a generator of 1 sinusoidal signals, radiating 2 and receiving 3 piezotransducers with cooled waveguides 4 and 5, amplifier 6, digital storage oscilloscope C9-87, synchronizer 8, plasma torch 9t

The device works as follows.

in a way.

The generator t of sinusoidal oscillations excites in a piezoelectric transducer, 2 more continuous acoustic oscillations, which through the waveguide 4 enter the plasma 10 and, after passing it through

OE 4 GS

with

OE C &

 the waveguide 5 reaches the receiving piezotransducer 3, the electrical oscillations from the output of which are amplified by the amplifier 6 and arrive at the input of the oscilloscope 7, which is started by the synchronizer 8 synchronously with the time of change of the operating mode of the plasma torch

Record the frequency of the received acoustic signals. Then, after a period of time t (this period is chosen less than the delay time between the radiators and the receiver), the frequency of the received acoustic signals is again recorded and the absolute values of the velocity at the beginning of C and at the end of Cj, the time interval & t :

С - -.2ЩЦ-1-4.Ш ,,. (f4. + Jf to „AND YM2ЈK + ufH - | bfK (2fu + ufK

), fH (2fu + & fH)

C

2L (fu + fO

x

At- | ifK (2fu + UЈK)

x (tЈts- ± L & (2fu + AfK)

 I ± D-)

JeifM (2fu + & fit)

where L is the distance between the transmitter and receiver; fu is the frequency of the emitted acoustic signal;

DЈm) -fii; Afk u.t) -fu,

Ј - frequency at the moment of reception.

From the above expressions for Sc and C Ј, it can be seen that to determine the absolute value of the speed of ultra sound in a controlled environment, it is not necessary to know the delay time of the signal in the acoustic channel.

The method was applied to measure the absolute magnitude of the speed of ultrasound in a low-temperature plasma,

" with

0

five

0

five

five

obtained using electric arc plasma torch. Measurement of the velocity of acoustic waves in a plasma was made during the launch of the plasmatron, when other methods did not allow controlling the physical parameters of the gas flow due to large temperature gradients. This is necessary when learning the mode of switching on or off plasmatrons, as well as jet and rocket engines.

Thus, the method makes it possible to determine the absolute value of the speed of ultrasound in a controlled medium with varying parameters and on the basis of this to determine the dynamic parameters of this medium, which is especially important when studying the mode of operation of powerful power plants

Claims (1)

Invention Formula The method of determining the speed of ultrasound in a medium with varying parameters, namely, that in a controlled medium excites continuous acoustic oscillations of a fixed frequency, receives an acoustic signal passed through the controlled medium, fixes the frequency of the received signal and determines the received difference frequency of the received and radiated signal the speed of ultrasound in a controlled environment, characterized in that, in order to increase the information content by determining the absolute speed of ultrasound, The acoustic signal passed through the monitored medium is received over a period of time less than the delay between the emission point and the acoustic signal reception point, the frequency of the transmitted signal is measured, and the absolute ultrasound velocity is determined taking into account the frequency of the emitted signal and the frequency difference between the emitted and the first received signal. between the radiated and the second received signal. Mil III /// Uh illlll I J V