SU1030656A1 - Ultrasonic flowmeter - Google Patents

Abstract

1. ULTRASONIC FLOWMETER, containing two reversible electroacoustic transducers placed on opposite walls of the pipeline and connected through a signal generation and reception unit to the inputs of the difference unit, as well as the first time interval meter, which is equipped with the first delay line, the correction unit and the phase velocity meter, consisting of two electroacoustic transducers placed symmetrically relative to one of the reversible electroacoustic transducers at equal distances from the pipe wall and connected one directly and the other through the second delay line to the inputs of the second time interval meter, with the outputs of the signal generation and receiving unit one directly and the other through the first delay line connected to the first time interval meter , and the INPUTS of the correction unit are connected respectively to the outputs of the block difference and the first and second time interval meters. 2. Flowmeter pop. 1, characterized in that the block of cortex: reaction is made as a first and second multipliers and an adder, the first inputs of the multipliers connected and connected to the first input of the adder, the second and third inputs of which are connected respectively to the outputs of the first and second about multipliers. with SG) S71 with

Description

The invention relates to measurement technology and can be used for measuring liquids in various public areas. Ultrasonic flowmeters are known that contain one or several pairs of electroacoustic transducers located on the pipeline at an angle to its axis and connected to a time interinterfacer. shafts, providing sensing controlled flow of fluid using ultrasonic signals. The resulting difference in the propagation times of the signals along the flow and against the flow of the fluid is directly proportional to its speed 1. The disadvantage of this flow meter is the low accuracy of the intention due to the effect on the measurement result of the ultrasound propagation velocity. The closest in technical essence to the invention is an ultrasonic pulse-phase flowmeter containing two reversible electroacoustic transducers connected via a switch, one input of which is connected to a generator, and the other to a logic circuit connected to a difference unit, the first of which the fall is connected to the first counter and the second through the second to the input of the code comparison circuit, the second input of which is via the third counter, frequency multiplier 1, and the circuit for measuring the angular multiplication factor It is connected to the time interval measurer whose input is connected to the switch outputs and the logic circuit, respectively. The device contains an additional generator, the outputs of which are connected to the frequency multiplier and through the second coincidence circuit, the second input is connected to the time meter and the terval, to the second counter, the output of the circuit is compared to the codes connected to the second inputs of the first circuit and the third counter 2. The disadvantage of this flow meter is the low accuracy. Measurement due to the dependence of the measurement result on the speed of propagation of ultrasound along the pipeline wall. The aim of the invention is to improve the accuracy measurement. The goal is achieved by the fact that an ultrasonic flow meter containing two reversible electroacoustic transducers placed on opposite walls of the pipeline and connected through the unit generating and receiving a signal to the inputs of the difference unit, as well as the first time interval meter, is equipped with a first delay line, a correction unit and phase velocity meter, consisting of two electroacoustic transducers placed symmetrically with respect to one of the reversible electroacoustic transducers Equal distances from the pipeline wall and connected one directly and the other through the second delay line to the inputs of the second time interval meter, the outputs of the signal generation and receiving unit one directly, and the other through the first delay LINE connected to the first time interval meter , and the inputs of the correction unit are connected respectively to the outputs of the difference unit and the first and second time interval meters. In this case, the correction block is made in the form of the first and second multipliers and sensor No. 1, with the first inputs of the multipliers connected and connected to the first input of the adder, the second and third inputs of which are connected respectively to В1,1 inputs of the first and second y of the heads. block diagram of the device. The ultrasonic flow meter consists of the short-circuit of two reversible electroacoustic transducers 1 and 2, fixed with the help of sound ducts 3 and 4 Hii opposite walls of the pipeline, unit 5 of generation and reception of the signal, difference unit 6, first LINE 7 delay, first meter 8 time interval, phase velocity meter 9 containing two electroacoustic transducers 10 and 11, the second delay line 12 and the second meter 13 time interval. The correction unit 14 contains two multipliers 15 and 16 and an adder 17. The ultrasonic flow meter operates from an ice pack. The signal generation and reception unit 5 generates electrical signals, Fia, npHMep pulses, under the action of 1 DIAGRAM reversible electroacoustic transducers 1 and 2, emit ultrasonic signals into the pipeline downstream and against the liquid flow. After the passage of the controlled fluid, these signals are again converted by converters 1 and 2 3 electrical and perceived by the signal generation and reception unit 5, which produces the formation of time intervals proportional to the propagation time of the fluid and against the flow of fluid D E-3 te9D-u :; csiwg) - -; - --t B, E-Dt rgCi-vJ / (cging)

where T, T are the times of ultrasound propagation along the flow and against the flow of the fluid; D is the diameter of the pipeline; C, b — velocity and angle of ultrasound propagation in a liquid;

2 - the distance between the points of input and output of the ultrasonic wave from the pipe wall; and - fluid flow rate;

V is the phase velocity of ultrasound along the pipeline wall, i.e. the speed of the front of the ultrasound wave along the wall; t is the propagation time

ultrasound in sound lines 3 and 4.

From these time intervals, a difference time interval is proportional to the measured flow velocity and

uT - T ,, - KuV, (.i)

where ku d / (c v cosS). The conversion coefficient of the KV flowmeter mohset be determined through the half-sum of propagation times T. and T

to jTiv - e

(TzV- e)

where (T .., + T) / 2-tjg

 To compensate for the dependence of the conversion factor and the measurement result T on the ultrasound velocity in the controlled fluid and in the pipe wall, the first meter 8 of the time interval and the meter 9 of the phase velocity of ultrasound along the pipe wall measure deviations of Tj and V from their nominal (average) values. When this meter 8 works as follows. The first pulses arriving at the input of the first delay line 7 and signaling the beginning of the time intervals T and T are delayed by it for a time equal to the nominal value of half the sum of the times T and Tj -. Therefore, the difference time interval Tj-Tg will be measured by the first meter 8 of the time interval.

 (.) VT. ,, (4)

where Y is the same as meter value 8 (for example, a digital code or voltage); K, - conversion factor

meter 8;

Tu is the nominal value of ° T. J.

The principle of operation of the meter 9 phase velocity ultrasound along the pipe wall is as follows. The ultrasonic signal propagating from the electroacoustic transducer 1, after passing the controlled fluid, propagates in the pipe wall and alternately enters the acoustic receivers 10 and 11. The time interval between the moments of the signals arriving at the receivers 10 and 11 will be equal to

t S / V (5)

where S is the distance between receivers 10 and 11 along the pipeline wall.

five

The signal from receiver 11 is additionally delayed by a second delay line 12 for a time equal to the nominal value of time t. Therefore, the second meter 13 time interval

0, the difference time interval will be measured and a signal is generated at its output

Dv v

(6)

V z v

-

YV,

five

t - S / VQ, tlV - V Vp uV V -V

Where

K „- conversion factor

the second meter 13 time interval;

0 t- - signal delay time

line 12 delay; V is the nominal value of the ultrasound velocity along the pipeline wall. The measured values of Y and Yy of dm5 are cut by blocks 15 and 16 multiplied by the output value of block 6 spay. After summing up the sum-1ator 17, the output values of blocks 15 and 16 multiply and the value of YA by its

0, a signal is generated, the value of which is determined as follows by expressions (3), (4), (6)

(Tj.v-e)%. T,

one

five

4HKvK, AT.), C-,)

de K - transformation coefficients.

With the right choice of conversion factors for 8 and 13 K meters and K

- l.5j lioli) v.

55

K.1 K / 1, T ..) b) (t,)

T

) (eight)

5 KV

Ho

changes in the ultrasound velocity in the controlled fluid Siv to the pipe wall V will lead to a change in the factors in the expression (7). These changes will be the same in magnitude, but opposite to

Claims (2)

1. ULTRASONIC FLOW METER, containing two reversible electro-acoustic transducers located on opposite walls of the pipeline and connected through the signal generation and reception unit to the inputs of the difference unit, as well as the first time interval meter, characterized in that, in order to increase the accuracy of measurements, it is equipped with the first delay line, correction unit and phase velocity meter, consisting of two electro-acoustic transducers placed symmetrically relative to one of the reversible electro Hub converters at equal distances from the pipe wall and connected one directly and the other through the second delay line to the inputs of the second time interval meter, with the outputs of the signal generation and reception unit one directly and the other through the first delay line connected to the first time interval meter, and the inputs of the correction block are connected respectively to the outputs of the difference block and the first and second time interval meters. ® 2. The flow meter according to claim 1, characterized in that the correction unit is made in the form of the first and second multipliers and an adder, the first inputs of the multipliers being connected and connected to the first input of the adder, the second and third inputs of which are connected respectively to the outputs of the first and second multipliers. Mvnl