SU1691686A1 - Method of determining water flow rate in open channels - Google Patents

Abstract

The invention relates to hydrometry and reduces the time spent on determining the flow rate of water in open channels. The flow velocity sensor is kept consistently but a certain distance from the bottom of the channel, also depending on the varying flow level. The flow rate of the water is calculated using a calculator into which the value of the flow velocity and its loss are entered. The dynamics of the flow are almost unchanged, since the speed sensor and the level sensor are not very large, the 2C and 2 s are compact.

Description

The invention relates to hydrometry and is intended to determine the flow rate of water in open, non-penetrating channels of a symmetrical section, operating in an irreducible mode on a straight channel section.

The purpose of the invention is to reduce the time for determining the flow of water.

FIG. 1 is a block diagram of a device for determining water flow; Fig. 2 shows the level sensor design in the kinematic circuit of the following level gauge; FIG. 3 shows the design of the flow velocity sensor; Fig. 4 is a general arrangement of the elements of the device for determining the flow rate.

The device for determining the water flow contains a level gauge 1 flow rate sensor 2, its output connected to a pulse shaper 3, a flow rate calculation unit 4, a flow sensor 5 electrically connected to control inputs of a reversible electric motor 6, whose shaft is kinematically connected through the pulley 7 and the cable-block system 8 with the sensor body of the 5 level, and with the shaft of the converter 9 of the angle of rotation of the shaft into the Gre code, the bit outputs of which through the converter 10 of the Grech code into the binary code are connected to the first and data inputs 11 calculation unit 4, and through the reduction gear 12 with peref coefficient m + 1, t cottages () of the same shaft electrodynamic

gate b kinematically connected with the second converter 13 of the psvorgna shaft to the Gre code; the bit outputs are through the converter 14 of the I code into the binary code connected to the nerves of the triple inputs of the adder 15; the second digit inputs of which are next connected to the converter of the 16 Gre code and binary code and inverter flask 17

PAINTS TO PYLRDYI, P0 1TP

ABOUT

about

about

00 0

l 18 of the angle of rotation of the shaft to the Gre code, whose shaft is kinematically connected to the shaft of the second reversing electric motor 19, which is also connected to the flow velocity sensor 2 by means of a rack and pinion movement mechanism 20, input 21 of the transfer of the binary adder 15 is permanently connected to the logical unit source 22 , the bit outputs of the adder 15 through the OR element 23 are connected to the first inputs of the AND 24 and 25 elements, the output 26 of the transfer of the adder 15 is connected directly to the second input of the AND 24 element and through the HE element 27 to the second input of the And 2 element 5, the outputs of the elements 24 and 25 are connected to the inputs of the reversible power amplifier 28, its output connected to the input of the second reversing electric motor 19, the timer 29 with its first output connected to the first input of the element 30, to the second input of which the output of the driver 3 is connected, also with the first input element and

31, the second input of which is connected to the output of the timer 29, the second output of the timer 29 is connected to the first input of the element OR

32, the second input of which is connected to the Fifth output 29, the third output of the timer 29 is connected to the first input of the OR element 33, the second input of which together with the first input of the OR element 34 and the reset input of the timer 29 is connected to the output of the installer 35, the fifth and sixth the outputs of the timer 29 are connected to the second inputs of the elements OR 32 and 34, respectively, the outputs of the elements OR 33 and 34 are connected to the installation inputs of the first 36 and second 37 binary counters, respectively, and to the inputs of the OR element 38, its output connected to the installation input of block 4 in The numbers, outputs of the AND elements 30 and 31 are connected to the counting inputs of the first 36 and secondly 37 binary counters, respectively, the outputs of which are bit-wise connected to the first inputs of the AND elements of the first 39 and second 40 groups, the second inputs of which are connected respectively to the fifth and the second outputs of the timer 29. The outputs of the elements AND of these groups are connected through the group of elements OR 41, one at a time, to the second information inputs 42 of the calculating unit 4, the outputs of which are connected to the block 43 of the controlled point of the telemechanics system.

A level 5 sensor is placed with a gap 44 in the pipe 45 of a small diameter, installed vertically and rigidly fastened in its upper part with a hydrometric bridge 46 compared to the flow width. The dielectric body 47 of the three-position level sensor 5 is hollow and contains a float 48 located between the lower 49 and top 50 holes of the housing 47 of the three-position level sensor and

equipped with an annular permanent magnet 51 of a horseshoe-shaped cross section, which provides control of the state of the magnetically controlled contacts 52, separated in height by the size of the insensitivity zone and installed in the vertical holes 53 of the housing 47 of the three-position level sensor sealed from moisture ingress into them. The float 48 and the level sensor housing 47 are provided in their lower

5 parts of the mounting inserts 54, 55, in addition, the float 48 is equipped with anti-wedging elements 56, and the pipe 45 in its lower part is equipped with a removable damping insert 57.

The vortex sensor 2 of the flow velocity is made in the form of a plastic thin-walled cylinder 58 mounted vertically inside the horizontal section of pipe 59 and having a longitudinal cut made between the vortex breathing blades 60, communicating the inside space of the cylinder 58 with the external medium, and the opposite edges of the cutout are provided with plates 61 , 62, are located with the possibility of parallel movement relative to each other and containing inside themselves segments 63 of foil interconnected and being encased s condenser chastotnozadayu5 boiling generator circuit 64.

The method of determining the flow rate is based on the principle of determining the average flow rate of water by single-point measurement of it on a representative vertical.

0 The most reliable velocity profile formula in open channels is parabolic j

weigh V Vmax ijm, where rj - relative depth; m is a coefficient reflecting 5 features of the channel and for the specified conditions of application of the method is constant. From this expression it follows that the flow rate can be represented as

j

0 h1 / m, where K Vm8x () m is the coefficient,

also taken constant in mathematical calculations; h is the distance from the bottom of the flow to the velocity measurement point. 5 According to the mean value, if the function f (x) is continuous on the segment a b, then on the interval (a, b) there exists a number such that

/ f (x) (Ј) (b-a) 0)

The function h m is continuous on the interval 0, H, i.e. similarly we have

one

one

H -1J.5

/ khmdh (khc) (H - O) Vcp (H - O)

about

The solution of this integral gives

m + 1 m

H

K h m I Vcp H m + 1d

from where

Vcp K H m K tv p1

where hcp is the distance from the bottom of the channel to the point where the measured speed is equal to the average.

From expression (4) we find hep.

icp

-t01 v

 (m + t)

H

less than

0.5

Experimental data indicate that the maximum flow velocity is sometimes not on its surface, but at a depth of (0.15-0.2) H from it. The velocity of the flow on the surface in this case is about 0.95 Vmax, and approximation of the real curve with the V kh1 / m dependence introduces a certain error in the definition of the average velocity, which is y-0.005

 0.01, which cannot

Significantly affect the calculation of the position of the ordinate of the average velocity on a representative vertical. It is also obvious that in reality the error is much smaller.

In the presence of wind due to surge, the level and velocity of flow can vary, therefore, under such conditions, the measurement of average velocity and level of flux without the use of windscreeners is not performed. t t +

slightly when t changes, so hep is determined from the measured H value with high accuracy. This again indicates that the average flow rate Vcp can be determined by one dimension on a representative vertical.

m vn

Value (

-) m varies greatly

at a distance of hCp- (

-) t N from the bottom

current. The presence of linear links between the average flow velocity and the average velocity on the representative vertical (VCp KP | JB), as well as greater stability at

five

)

ten

15

20

thirty

35

40

45

50

55

various water levels kpäff1Ch {n1 - azi Kr (especially in symmetric v fixed sections) are not only unquestionable, but also serve as the basis for the creation of automatized and automatic devices for express determination of the speed and parity of water in open channels the same level gauge allows continuously monitoring the value of H g, any time instant to calculate the area S of the living section, and the measured value VCp at the point hcp water consumption

The operation of the device for determining the flow of water in the open channels is as follows

In the initial state of the devices and the voltage supplied to its blocks, the PigacciC level gage 1 supplies to the first information inputs 11 of the block 4 of the calculation a two-digit number corresponding to the flow rate at the location of the flow rate. A float 4o (see Fig. 2), placed in the cavity of the housing 47 of the three-position contact sensor 5 and equipped with a permanent ring magnet 51 of the horseshoe-shaped machine in the initial state of the MOVSI device, is in any permissible position of the housing 47 of the level sensor

When the float 48 is located at one mz of the extreme positions, the permanent ring magnet 51 is located near one m of the magnetocontrolled contacts 52 of the vertical channels inserted in the corresponding openings 53 of the vertical channels made in the body 47 of the level sensor 5. The matter of the sensor core can be any dielectric, for example, nylon. When the lion of the standing ring magnet 51 is boosted to any of the magnetically resistant contacts 52, it is short-circuited and the first gear-bearing reversing electric motor 6 closes. If the upper magneto-equalizing contact 52 is closed, then the level 5 body 47 of the sensor 5 is lifted by means of a cable block system 8 and the pulley 7 to the same level as the closed upper magnetically controlled contact 52 is open, the first gear reversing electric motor 6 being disconnected. Similarly, the closure of the lower magnetically controlled contact 52 causes the first gear reversing motor 6 to be switched on to lower the level sensor body 47 until the bottom magnetic contact 52 is open again, which will turn off the first gear reversing motor 6. Possible the bounce of magnetic contacts does not affect the performance

electric motor, which is an inertial link. The accuracy of the level measurement is determined by the width of the dead zone of the three-position level 5 contact sensor and depends on the width of the annular permanent magnet 51 and the distance that the magnetically controlled contacts 52 are spaced apart. In this case, the level measurement error is ± 0.3 cm.

The shaft of the first reversing motor b is kinematically connected with the shaft of the converter 9 of the angle of rotation of the shaft into the Gre code, in turn connected to the converter 10 of the Gre code into a binary code, the outputs of which are bit-wise connected to the first information inputs 11 of the calculation 4. Therefore, a binary number is permanently present at these inputs corresponding to the level H of the stream.

In addition, the shaft of the first gear reversing motor 6 is also kinematically through the gearbox 12 with the coefficient, l

transfer amount (---) t (in general

case) is connected with the converter shaft 13 of the angle of rotation of the shaft into the Gre code, with its outputs connected with the inputs of the converter 14 of the Gre code into a binary code, the bit outputs of which will also constantly have a binary number corresponding to, in general,

m

m +

will be present at the first inputs of the adder 15.

When the system is turned on, the flow rate sensor 2 is not necessarily at the flow point, the ordinate of which corresponds to (---) m from the flow level H. To further explain the operation of the device, it is necessary to choose the value of the coefficient t. For simplicity, we take m 2. Then

(--- d) Suppose that when turned on

ГП т 1 У

device level H was 513 cm. Suppose also that speed sensor 2 was, for example, at a distance of 235 cm from the bottom of the stream, which in binary form corresponds to the number 11101011. This is exactly the number that will be present at the output of the 16-to-B code in the converter. The inverter block 17 converts this number into the inverse 00010100. As already mentioned, the first bit inputs of the adder 15 contain a number corresponding to (tm) 1 N or about 513

228 (in binary form 11100100). On the second

(

-) tn. This number is also constant.

0

five

0

five

0

five

0

five

0

five

bit inputs 15 of the binary adder 15, the number 00010100 is present, and the input 21 carries the low bit of the binary adder 15 from the source 22 and constantly sends a signal of the logical unit. As a result of the summation at the outputs of the binary adder 15, we get: 00010100 +11100100

one

0.11111001

The symbol O to the left of the comma indicates the appearance at the output 26 of the high-order transfer of the binary adder 15 of the logical zero signal, which goes to the second input of the first element AND 24. and is inverted by the element NOT 27 into the signal of the logical unit, to the second the input of the second element is AND 25. The first inputs of both elements AND 24, 25 are given a signal of the logical unit from the output of the first element OR 23, the inputs of which from the bit outputs of the binary adder 15 receive the number 11111001, obtained as a result of the summation operation. Since at both inputs of the element 25 there are signals of a logical unit, this signal from the output of the element 25 through a reversible power amplifier 28 will turn on the second reversible electric motor 19 to lower the flow velocity sensor. If, however, when the system is turned on, the speed sensor is at a distance, for example, 200 cm from the bottom of the stream, which in binary form corresponds to the number 11001000, and in the inverse form - 00110111, then when summing up in the binary adder 15 we get

00110111

11100100 1

1.00011100

The unit to the left of the comma indicates the appearance at the output 26 of the high-order transfer of the binary adder of the signal of the logical unit. This signal is fed to the second input of the first element AND 24 and in the form of a logical zero signal (due to the inversion of the element NOT 27) to the second input of the second element AND 25. The second inputs of these elements from the output of the first element OR 23 receive a logical one signal, since its inputs from the binary output of the binary adder are given the number 00011100.

The presence at both inputs of an AND 24 signal of a logical unit causes the signal of a logical unit si at the output of an AND 24 element, which, P turn, leads to the inclusion of

f +

a strong power amplifier 28 of the second reducer reversible electric motor 19 to raise the flow velocity sensor. Thus, the presence of a mismatch leads, depending on its sign, to turn on the second reversible electric motor 19 either to lower or to raise the flow velocity sensor 2.

In synchronization with the movement of the flow rate sensor 2 at the second bit inputs of the adder 15, the information will change until the speed sensor 2 is moved to the distance

-) t from the flow level H (in this

m

(m -f 1

4 example - to the level H 228 cm).

In the case of transferring the sensor 2 flow rates to a plant of 228 cm from the channel bottom, the binary number will be received by the binary number 11100100, and the second will be inverse to it 00011011. Taking into account the transfer of the least significant bit of the binary adder 15 signal to the second inputs logical unit, the adder will sum up 4 11100100 00011011 1

1.0000000

and the combination 00000000 comes from the bit outputs of the binary adder 15 to the inputs of the first element OR 23 and as a logical zero signal at its output associated with the first inputs of the AND 24 and 25 elements. This leads to the appearance of the logical zero signal at the outputs both elements And 24, 25 and off through the second reversible power amplifier 28 of the second reversing electric motor 19 - the error is eliminated. Thus, the speed sensor displacement system is constantly operating in the error correction mode, maintaining

distance sensor () 1 from bottom

flow. Since the resolving mismatch in the tracking mode is equal to one quantization step of the transducer 13 of the angle of rotation of the shaft to the Gre code, and the speed of elimination by its gear motor it is, for example, 2 rpm, there is no overshoot.

The measurement of the flow velocity is based on the calculation for the period T of the number of Karmanz vortices. formed behind the plastic thin-walled cylinder 58 and the perceived blades 60, which alternately, in the same way passing vortices, deviate from their original position in the direction of the axis

the symmetry of the horizontal segment of the group

g ...

59. At the same time, plates 61 with segments of the Foil move relative to each other, the capacitance of the frequency-dropping varies

5 generator circuit 64 and the frequency of the pulses at its output, i.e. we obtain frequency-modulated oscillations, which, after being processed by a shaper of 3 pulses, including the frequency discriminator

0 arrive at the pulse counters.

The frequency of these pulses formed after demodulation is proportional to the flow velocity at the measurement point. But the current as this point is located

5, in up ,,

on at a distance (- -, -) H from the bottom of the cana

la, then the measured velocity is equal to the average flow velocity at the representative vertical

0UB - Ki f.

where Ki is a constant coefficient taking into account the diameter of a thin-walled cylinder 58 and the criterion (coefficient) of Strouhal.

The average speed of the entire stream in

5 of this channel section Vr (. As noted, is defined as VCp KD Un, r e

Vcp - K f

where K - Kr KI is defined, ablzgoerome no.

0Significant CSC-FF-tion and K, ak and others

Constant values (b the width of the bottom at the measurement site; tg a-tchngeng. angle of inclination of the slope of the skimt aperture) are entered into the computational device for calculating the water flow in advance by means of a key input / output information (in the block diagram for simplicity, this is reflected) The measurement accuracy of the scraper depends on the interval T of the integration time.

Therefore, to ensure the expressiveness of the flow determination, the flow rate must be measured in advance. For this purpose, two recording memories are used, which are the number of pulses.

5 breaks through the flow rate, alternately, and information is read from the record to which it was recorded.

0Calculation block 4 provides the following operations: calculation of the flow rate V; p K f; calculating the area S of the living cross-section of the stream from constant values of b, tg / and measured

5 to the H value of the flow level (for the trapezoidal bed S K (S H ig a); the calculation of the flow O is V cp-S; the transfer of the calculated Q value to the memory of the block 43 of the controlled point of the telemechanics system.

After switching on the power supply, the binary counters 36, 37 (respectively, through the fourth 34 and third 33 OR elements) and calculation block 4 (through the fourth 32, third 33 and Fifth 38 OR elements) are zeroed with a signal from the installation unit 35, generating a waste pulse. At the same time, the timer 29 is reset.

In the future, the work of the entire system proceeds as follows. The signal from the first output of timer 29 opens the third element I 30, through the second input of which the first binary counter 36 records the sequence of pulses from the speed sensor 2, converted to standard parameters by the driver of 3 pulses, over time T.

Simultaneously with the beginning of the recording of pulses into the first binary counter 36, the signal from the second output of timer 29 allows the transmission through the second group of elements AND 40 and the group of elements OR 41 to the block 4 for calculating binary information from the second binary counter 37, all of which after the initial reset are written zeros. In this case, through the second element OR 32, the calculation is allowed to be performed by the calculation unit 4, the first result of which will naturally give a zero result.

A pulse from the third output of the timer 29 through the third element OR 33 zeroed the second binary counter 37 and through the fifth element OR 38 the computing device 4.

The pulse from the 4th output of timer 29 opens the fourth element I 31, through the second input of which to the second binary counter 37, for the time T, pulses are recorded, the number of which is proportional to the flow velocity. The impulse from the fifth output of the timer 29 permits (through the first group of elements AND 39 and the group of elements OR 41 the input of data from the first binary counter 36 to the computing device 4 and gives it (through the second element OR 32) permission to carry out calculations of water flow, after which the result of the calculations replaces the result of the previous calculation of the flow rate in the memory of block 43. The impulse from the 6th output of timer 29 wraps the first binary counter 36 (through the fourth element OR 34) and the computing device 4 (through the fourth 34 and fifth 38 element OR). Next out A pulse appears at the first output of timer 29, etc., and the next flow calculation cycle starts.

Thus, during the entire operation time of the device, numbers are written alternately in binary counters 36, 37 proportional to

flow rates, i.e. at any moment on the bit outputs of one of the counters there is a binary number proportional to the flow rate at which the computing device 4 performs

0 calculates its average speed, and then (by the values of b, H, tg a) the area of the living section and the flow rate.

Claims (4)

1. The method of determining the water flow in 5 open channels of symmetrical section, consisting in measuring the average flow rate, measuring the flow level and calculating the flow rate taking into account the area of the living section of the stream, so that, in order to reduce the flow rate, measure values of the average flow rate are carried out cyclically, and in each cycle the measurement is performed on the vertical 5 axes at a distance from the bottom constituting eGP ul. , (t + t} n. where m is an exponent in the ratio relating the distance from the bottom of the channel to 0 the flow rate at a given point, determined experimentally for a given segment of the channel; H is the measured value of the flow level. five 2. A device for determining the flow rate of water in open channels, containing successively connected flow velocity sensors and a pulse shaper, a level gauge and a flow calculation unit, which so that, in order to improve speed, a reducer is inserted in it, the first converter rotation angle to Gre code, first Gre code converter to binary code and adder, connected in series reversible power amplifier, reversible electric motor reducer second converter la rotation in Gre code, a second converter 0 Gre code in binary code and a block of inverters, connected by outputs to the second group of inputs of the adder, timer, first and second binary counters, first, second, third and fourth elements And, first. 5 second, third, fourth and fifth elements OR. the first and second groups of elements AND, a group of elements OR, an inverter, an installation unit, a rack and pinion mechanism for moving the flow velocity sensor and a signal source of logical units, output for the transfer of an adder connected to the input, a group of outputs connected via the first element OR to the first inputs of the first and second elements AND , output transfer of the adder is connected to the second input of the first element And, directly, and to the second input of the second element And through the inverter, the outputs of the first and second elements And are connected to the inputs of the reverse power amplifier, the output of the installation block is connected to the timer setup input, to the first input of the third and fourth OR elements, whose outputs are connected respectively to the reset inputs of the first and second binary counters and to the inputs of the fifth OR element connected to the first input of the calculator, the second the input of the second OR element connected to the output, the first timer output is connected to the first input of the third AND element, the second timer output is connected to the first input of the second OR element and to the gate input the first group of elements is AND, the third output of the timer is connected to the second input of the third element OR, the fourth output of the timer is connected to the first input of the fourth element AND, the fifth output of the timer is connected to the first input of the second element OR, and the sixth timer output is connected to the second input of the fourth OR element, the pulse driver output is connected to the second inputs of the third and fourth AND elements, the outputs of which are connected to the counting inputs of the first and second binary counters respectively, the information outputs of which are connected respectively to the inputs of the first and second groups of elements AND whose outputs are connected to the corresponding groups of inputs of the group of elements OR whose outputs are connected to the first group of information inputs of the calculator, the second group of information inputs which is connected to the information outputs of the level gauge, kinematically connected to the gearbox, the gearbox of the reversible electric motor is kinematically connected to the flow velocity sensor through a rack-and-pinion movement mechanism, the level gauge in the form of serially connected level sensor, reversing motor, Gre code and code converter Gre in binary code. and the shaft of the reversing motor is connected by a level gauge through a pulley and a cable-to-block system. 3. The device according to claim 2, characterized in that the level sensor is made in the form of a float, equipped with an annular permanent magnet and a mounting insert in its lower part and placed in a hermetic case, which, in turn, is placed in a vertical A small-diameter pipe, rigidly fastened with its upper part to the hydrometric bridge, and in the lower part containing a replaceable damping insert, in the vertical openings of the level sensor body are installed magnetic contacts separated by a height of width 10 reality. 4. The device according to claim 2, characterized in that the flow velocity sensor is made in the form of a plastic thin-walled cylinder mounted vertically inside a horizontal pipe segment and having a longitudinal cut made between the vortex blades, which communicates the inside space of the cylinder with the outside medium, moreover, the opposite edges of the cutout are provided with plates arranged for parallel movement relative to each other and containing foil sections interconnected to each other and in lined by capacitor plates of the alternator's frequency-dependent circuit. st 1C FIG. 2 59 nineteen 46 .four