SU970223A1 - Flow speed ultrasonic meter - Google Patents

Description

(54) ULTRASONIC FLOW SPEED METER

The invention relates to the field of acoustic measurements and can be used in various sectors of the national economy for measuring the velocity of the sources of gases, monitoring the progress of technological processes and controlling the velocity of flows, for example, in aerodynamic installations.

Ultrasonic flow velocity meters are known, comprising two reversible electroacoustic transducers, a transmitter, a pulse signal receiver, a time interval-digit converter, a unit for calculating inverse digital values, and a subtractor flj.

A disadvantage of the known devices is the inoperability when measuring the speed of supersonic flows, the speed of which exceeds the value of the speed of ultrasound in the stream.

The closest in technical essence to the proposed ultrasonic flow velocity meter contains two reversible electroacoustic transducers, a transmitter, a receiver, a synchronizer, a time interval-digit converter, a block of the reference digit, a reverse digital value calculator, a subtractor, two totalizers, three keys , digital-to-analog converter, differential circuit and switch f2.

A disadvantage of the known device is the presence of a preparatory mode of operation of the device, in which

10, acoustic pulses are emitted against the flow direction, i.e. The device is inoperable at supersonic flow rates. The speed of this device is limited by the duration of the received acoustic pulses. The purpose of the invention is the extension of functionality due to the possibility of measuring

20 speeds of supersonic flows and

increase measurement speed.

The goal is achieved by the fact that a third electroacoustic transducer, a multiplying device, a second input device, a second time interval digit and a second unit for calculating the reciprocals, the first electro-acoustic transducer

keys to the transmitter output, the second through the first input device; the first time interval converter is a digit and a duplicating device connected to the input of the first block for calculating return values, the third electroacoustic converter through a second input device, the second time interval converter is a digit and the second block for calculating feedback values is transmitted to the second input of the subtractor, the converter control inputs the time interval the digit, the return calculation blocks, the reference digit block and the second input device are connected to the sync outputs torus, the unit outputs the reference numbers connected to the second inputs of the first and second converters timeslot - figure.

Figure 1 is an eLock diagram of the device; 2, graphs illustrating the operation of the device.

The device includes an irreversible electroacoustic transducer 1 and two acoustoelectric transducers 2 and 3, a transmitter 4, two input devices 5 and 6, a synchronizer 7, consisting, for example, of pulse generators and delay circuits, two time transducers - digit 8 and 9 , a multiplier device 10, a reference figure block 11, two blocks 12 and 13 for calculating the reciprocal digital values, and a subtractor device 14.

The electroacoustic transducer 1 is connected to the output of the transmitter 4. Acoustoelectric transducer 2 is connected to the input device 5, the output of which is connected to the first input of the converter 8 time interval - digit and the synchronizer input 7. The output of the converter 3 is connected to the input of the multiple. The device 10, the output of which is connected to the input of the block 12 for calculating the reciprocals. The output of block 12 is connected to the first input of the subtractor 14. Acoustoelectric transducer 3 is connected to the input device b, the output of which is through the first input of the transducer 9 time interval - digit and the block 13 for calculating the return values connected to the second input of the subtracting device 14. the first output of the synchronizer 7 is connected with the input of the transmitter 4 and the control inputs of the transducers B and the 9 time interval digit. The second inputs of converters 8 and 9, respectively, are connected to the first and second outputs of reference block 11. The control inputs of input devices 5 and b, reference figure block 11, blocks 12 and 13 of the calculation of return values and subtracter 14 are respectively connected to second, third, fourth and fifth outputs of the synchronizer 7.

Ultrasonic speed meter supersonic flow works as follows.

Transmitter 4 is periodically triggered by pulses coming from

synchronizer output 7, and

the repetition period T of the triggering pulses is set according to the condition, where -fj is the transit time of the i-th acoustic pulse in the direction of flow from the electroacoustic converter 1 to the electroacoustic converter 3. At the same time, excitation pulses with period T arrive at the electroacoustic converter. Acoustic pulses emitted only along to the direction of flow, are taken by converters 2 and 3 and through the input device 5 are fed to the input of the synchronizer 7 and the converter 8 time interval - digit , and through the input device b arrive at the converter 9. At the moment of time t ;, + tj, where T is the time of the first acoustic impulse for the distance between the converter E 1 and converter 3, the pulse coming from the first output of the synchronizer 7 to the input control converter 9, digital value

N T is rewritten into time block registers, 4 hr ZZ utl. + I

13. at, moment

+ where / j. "DT is the delay time in the synchronizer circuit 7, and tj is the time interval between reception (1-1) and i-ro pulses, the reference digit block 11 is started, and the negative reference digit / -NO / S T is input to the second input of converter 9, which is summed up with the contents of the converter registers 9. After the end of the summation at the moments

remeni t.4 tr -i-Ilutj + GL. ct

the converter 9 receives pulses from the first output of the synchronizer 7, after which the current digital value is summed,

Registered transform. paddle 9, and aN-E / sfl values.

Thus, at every i-th instant of time, an i-digit value N is formed according to the expression

 ,,

M N45 :: dN:., - (i-i)., Sa)

3 where

C + f cosc V (t) ai is the average value of the p belt speed V (t) of the flow under study during the time interval T.; the speed of the ultrasound measuring current; the distance between electroacoustic converters 1 and 3; ot is the angle between the base d and the velocity vector of the flow under investigation. After each arrival the digital value N {at the output of the converter 9 by the synchronizer pulses 7 coming from its fourth output, block 13 is started. After the calculations are completed, in block 13, a digital value is periodically generated at its output 1 / N |, which is written to the registers of the first term of the subtractive device 14, after which the block 13 is reset and prepared by the pulses of the synchronizer 7. The electroacoustic converter 2, the input device 5 and the transducer The transducer 8 time interval. The digital work in the same way as the transducer 3, the input device 6 and the transducer 9, the time interval is a digit. Thus, in each s.th instant of time, a digital value N is generated at the output of converter 8) according to the expression N.m.ch: unN.-ci-im jS t: i, (5) where N.Hf is a digital value, which is formed at the output time of the transducer 9, is proportional to the transit time of the first acoustic pulse in the direction of flow between the electroacoustic transducers 1 and 2; lm | - the current digital value is proportional to the time interval between two acoustic pulses received by the electroacoustic transducer 2 ;. -jJi- -time passing by. C v | cos () the direction of flow of the 1st acoustic pulse between the electroacoustic transducers „f 1 and 2; V ;;: 4- | VWol is the average value of the variable speed for the research & stream flow over a time interval, fj, d2 is the distance between the electroacoustic transducers 1 and 2. Angle: L (Fig. 1) is set to condition 0 "TL" Ti / 2f so that converter 3 does not cover the converter 2. Each digital value N from the output of converter 8 is fed to the input of the multiplying device 10 and multiplied by the value K, which is entered pre-programmed into the multiplying device 10. After each digital value K -y multiplies the output The device 10 by the synchronizer 7 Sh-pulse arriving from its fourth output starts the block 12 for calculating the reciprocal digital values. After completing the calculations in the block. 12, a digital value of 1 / K-N is periodically generated at its output, which is recorded in the registers of the second set subtractive device 14. After this, the block 12 is reset and prepared by a synchronizer pulse 7. In discrete times t, + (i - () T + S:, where L is the total computation time, the output of the reading device 14, according to the expressions () and (6), receives digital values Mi / N --- f / KN- –f - / K-Tj. When the condition cf «J // 2, is valid, the cosm of the cos (c6 + cl). At the same time, the IF value M is expressed by the formula M (t) dt (USU;) CO v (i, a. Ci4roea value M, - arrives at the input of the subtracting unit 14 by the repetition period T of the probing bushy impulses, T T Tj. ultrasonic measurement of the speed of supersonic flows, the period of fluctuations of which is much less than the time of passage of the acoustic impulse of the base distance and in the direction of flow. The integration time is for the first time / less to the value of CL 7,

so up to a value equal to the difference in the transit time of acoustic pulses of base distances d and d in the direction of flow, with 0. “T, This is ensured. increase in speed and decrease in dynamic error not less than in T / o ;; time.

The use of the proposal is particularly useful in monitoring and controlling processes in aerodynamic supersonic installations, as well as in scientific research: explosive processes.

Claims (2)

1. Forward Germany No. 2431346, cl. G 01 P 5/00, 1976. 2. USSR author's certificate for application number 2820222 / 18-10, cl. G 01 P 5/00, 1979 (prototype). Vshod