SU1168843A1 - Method of measuring relative pulsations of ultrasound velocity in moving medium - Google Patents

Abstract

METHOD OF MEASUREMENT OF RELATIVE PULSATIONS OF ULTRASOUND SPEED. In a MOVING MEDIUM, in which a pulse of ynpyroij waves is excited perpendicular to the velocity vector in a moving medium, the transit time of this ig-pulse of the base distance is measured and this time is used in measuring the relative pulsations of the ultrasound velocity, characterized by the fact that increase the accuracy of measurements, excite the second impulse of the elastic wave, shifted relative to the first by the time interval At, which is longer than the duration of the pulses, but much less than the time of their propagation at the base the distance is measured, the time interval Lt between two pulses after the passage of the base distance, and the relative pulsations of the ultrasound velocity are calculated using the formula C-,; -one; + where c (t) dt Ci .: t; t-, t; .V c (t) dt .S. m titi); - the value of the ultrasound velocity averaged over the time interval; , tg + nd, cz C.-1 value of the velocity of the ultrasound interval averaged, t. rr t + T + +, time u о-T / 1 - time of passing through the base distance of the first impulse of the elastic WAVE; til is the moment of emission of the first impulse of an elastic wave in the i-OM 00 00 measurement cycle, S is the difference in the propagation times of the first and second im00 pulses of the elastic wave at the base distance in the i-th id1 of the measurements.

Description

1 The invention relates to non-destructive testing and can be used to measure near-instantaneous relative pulsations of ultrasound velocity in a moving medium, depending on the physical and mechanical parameters of these media. The aim of the invention is to improve the measurement accuracy. The drawing shows a block diagram implementing this method of measurement. The circuit contains receiving 1 and radiating 2 acoustic transducers located at a given base distance d. Converter 1 is connected in series with receiver 3, digital measuring device 4 and synchronizer 5. A generator of 6 paired video pulses is connected to converter 2. Three outputs of the synchronizer 5 are connected to the inputs of the receiver 3 of the digital measuring device 4 and the generator 6. The method of measuring the relative pulsations of the ultrasound velocity in a moving medium is carried out as follows. At the moment tj from the generator 6, the pairs of video pulses are emitted to the radiating acoustic transducer 2 by two pulses shifted relative to each other by the time interval At. Moreover, this interval ut is longer than the duration of the pulses, but much shorter than the time of their propagation at the base distance. Transducer 2 excites two pulses of an elastic wave perpendicular to its velocity in the studied moving medium. The digital value of the specified time shift is recorded in the memory of the digital measuring device 4. The receiving acoustic transducer 2 installed at the base distance d from the radiating acoustic transducer 1 receives these two elastic wave pulses. These elastic wave pulses, converted by the transducer 1 into electrical pulses through the receiver 3, enter the digital measuring device 4, where the time interval e between the received pulses is fixed after the base distance has passed. Selection of a pair of received pulses is carried out by signals from the second output of the synchronizer 5 to the receiver 3, and from the third output to the digital measuring device 4. Then, in each i-th measurement cycle, the relative value of D.S., pulsations of the ultrasound velocity are calculated According to the formula LSG ,, d cCtiJi. (-) с + b ;. The method of measuring the relative pulsations of the ultrasound velocity in a moving medium. Permits measurements of these relative pulsations to be highly accurate, since, when probing the studied medium, by two elastic wave pulses shifted for a short time, the results obtained are averaged over a smaller time interval.

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Claims (1)

METHOD FOR MEASURING RELATIVE ULTRASONIC SPEED PULSATIONS In a MOVING MEDIUM, namely, that an elastic wave impulse is excited perpendicular to the velocity vector in a moving medium, the time it takes for the pulse to travel the base distance is used and this time is used to measure the relative pulsations of the ultrasound velocity, which excite in order to increase the accuracy of measurements the second pulse of the elastic wave, shifted relative to the first by a time interval At, which is longer than the duration of the pulses, but significantly less than the time of their propagation at the base distance At home, measure the time interval of the AT between two pulses after passing the base distance and calculate the relative pulsations of the speed of ultrasound according to the formula ^_ C; _O '& C? With _n0 is the ultrasound velocity averaged over the time interval, t _a + A _t ] · the ultrasound velocity averaged over the time interval '> T) ⁺ ^ 1 + ⁺ AmT', the transit time of the base distance of the first pulse of the elastic wave; t.j is the moment of radiation of the first pulse of the elastic wave in the i-th measurement cycle S; - the difference between the propagation times of the first and second pulses of an elastic wave at a basic distance in the i-th measurement cycle. 1 ^ 8911 1 1168843 2