SU1755159A2 - Device for testing conducting liquid flow turbulence parameters - Google Patents

Description

The invention relates to hydrophysical studies and can be used in experimental hydrodynamics for determining turbulence parameters, in oceanology for measuring the flow rate of an electrically conductive fluid, conductivity and temperature and for studying the fine structure of ocean water in one sensitive area of pulsations, and is an improvement of the known device .

According to the main author. St. No. 1679338, a device is known for measuring the turbulence parameters of a flow of an electrically conducting fluid consisting of a four-electrode primary transducer made in the form of a body of rotation from a dielectric-coated permanent magnet, the electrodes in the transverse gap of the nose part symmetrically with respect to the symmetry axis of the electrodes are arranged in pairs

the external electrodes are measuring, and the internal current of the differential amplifier, whose inputs are connected to the measuring electrodes, the first low-pass filter, whose input is connected to the output of the differential amplifier, and the output is the first output of the device, the band-pass filter, whose input is connected to the output of a differential amplifier, a first synchronous detector, whose input is connected to the output of a band-pass filter, a reference voltage source, an adder, whose inputs, respectively, are connected enes to the source of reference voltage and the output of the first synchronous detector, a controller, whose input is connected to the output of the adder, controlled oscillator, a control input coupled to an output of the regulator, the converter voltage - current, which input is connected to the output control u

generator, and the outputs of which are connected to current electrodes, the second synchronous detector, the input of which is connected to the output of the controlled generator, the comparator, the input of which is connected to the output of the controlled generator, and the output is connected to the reference inputs of the first and second synchronous detector, the second a low-pass filter and a selective amplifier, whose inputs are connected to the output of the second cr 1 of a synchronous detector, and the outputs are, respectively, the second and third outputs of the device

The known device can be used only for small, close to zero, values of salinity pulsations for calculating density fluctuations, heat flux and pulsation. Since in experimental studies salinity pulsations are often not equal to zero, this leads to an error in determining the pulse, heat flux and mass transfer.

The purpose of the invention is to improve the accuracy of | lernii and expand the functionality of the device due to the joint measurements in one sensitive area of pulsations of flow rate, conductivity and temperature.

Fig 1 shows the primary converter; Fig. 2 is a functional diagram of the proposed device for measuring turbulence parameters of a flow of an electrically conductive liquid.

The device contains a thermoconverter 1, mounted coaxially to the axis of symmetry of the primary converter, made in the form of a body of rotation of a permanent magnet 2, covered with dielectric 3 In the transverse gap (type A), the nose of the primary converter is symmetrically relative to the axis of symmetry located in pairs measuring 4, 5 and current 6 , 7 electrodes The device contains the first differential amplifier 8. the second converter voltage - current 9, the second differential amplifier 10, the first band-pass filter 13, the third sync onion detector 14, voltage source 15, first synchronous detector 16, switch 17, third low pass filter 18, adder 19 comparator 20, linearizer 21, second synchronous detector 22, regulator 23, fourth low pass filter 24, high pass filter 25 , second lowpass filter 26, selective amplifier 27 first voltage converter -current 28, controlled oscillator 29

Thermal converter 1 is installed coaxially with the axis of symmetry of the four-electrode primary converter, while it is installed on the outer surface of the dielectric coating 3

The inputs of the differential amplifier 8 are connected to the measuring electrodes 4 and 5, the Output of the differential amplifier 8 through the low pass filter 12 is connected to

to the terminal of the first output of the device Simultaneously the output of the differential amplifier 8, through the first band-pass filter 11 is connected to the input of the synchronous detector 16 The output of the synchronous detector 16 through

a series-connected adder 19, a controller 23, a controlled generator 29, and a voltage-current converter 28 are connected to current electrodes 6 7. The second input of the adder 19 is connected

to the output of the source of opopny voltage

15 The output of the controlled generator 29 is connected to the comparator 20, the output of which is connected to the reference inputs of the first

16 and the second 22 synchronous detectors, the signal input of the second 22 synchronous detector is connected to the output of the controlled generator 29 and the output of the second synchronous detector 22 through the second low-pass filter 26 and the selective

the amplifier 27 is connected respectively to the terminals of the second and third output devices. The input of the switch 17 is connected to the source of the reference voltage 15, the reference input of the switch 17 is connected to

the output of the comparator 20, and the output is connected to the input of the second band-pass filter 13, the output of which is connected to the input of the second voltage-current converter 9, the outputs of which are connected to the outputs of the sensing element of the thermal converter 1, which are connected to the inputs of the second differential amplifier 0 whose output is connected to the input the third synchronous detector 20, and the output is connected to

the input of the third low-pass filter 18, the output of which is connected to the first input of the linearizer 21, the second input of which is connected to the source of the reference voltage 15, and the output is connected to the inputs of the fourth

low pass filter 24 and high pass filter 25, the outputs of which are respectively the fourth and fifth outputs of the device.

The device works as follows. An alternating current H of sinusoidal form is supplied to the current electrodes b and 7 from the two outputs of the first converter 28, the value of which is determined by the following relation

And L) 29 / Ri, where IJ2Q is the output voltage

controlled oscillator 29, Ri is the current resistor of the first converter 28, the voltage is the current. The first differential amplifier 8 measures and amplifies by Ki times the potential difference of the measuring electrodes 4 and B, the output voltage Us of the first differential amplifier 8 is determined by the following relation:

Us h (Rat + 1 / (ft s)) Ki h Ki Kpr-V1, (1)

where PJ is the active resistance of the electrolyte solution between the current electrodes; c is the total capacity of the double electric current electrode layer; o is the circular frequency of the output voltage of the controlled oscillator 29; CRC is the coefficient for converting the ripple rate V1 to voltage. To isolate the second component of relation (1), the first low-pass filter 12 is used, which amplifies this component by a factor of. The output voltage Ui2 of the first low-pass filter 12, directly proportional to the pulsations of the flow rate of the electrically conducting fluid, is determined by the following relation 1

Ul9 Ul5 + U29R cKlK3 / Rl.

(five)

The proportional integral controller 23 continuously adjusts the output voltage U29 of the controlled oscillator 29 in such a way as to maintain the output voltage Uig of the adder 19 to zero. Therefore, the output voltage Shae of the controlled oscillator is determined by the following relation:

U29 -UiskRiK / (Ki Xa).

(6)

where A is the conductive constant of the electrical conductivity converter; k is the magnitude of the instantaneous values of conductivity.

The second synchronous detector 22 performs the detection of the output voltage IJ2Q. Its output voltage is directly proportional to the values of. The second low-pass filter 26 extracts and amplifies K times the average values of the Coupling conductivity. Its output voltage IJ26 is determined by the following relation1

Ui2 KrK2 Knp-V1.

(2)

The first band-pass filter 11 is tuned to the frequency of the output voltage of the controlled oscillator 29. Its output voltage is (Un is defined by the following relation: 35

Uii h (Rx + 1 / fjft) with Ki K3, (3)

where Cs is the gain of the first band-pass filter 11.

The first synchronous detector detects the output voltage Un. Since the incoming signal of the comparator 20 to the reference input of the first synchronous detector 16 and the output signal U29 of the controlled oscillator 29 are phase-locked, the unipolar output voltage Die of the first synchronous detector 16 is determined by the following relationship:

Ui6 liRxKiK3 (4)

The adder 19 performs the summation of the opposite-polarity output voltages Ui6 and Uis, respectively, of the first synchronous detector 16 and the source of the reference voltage 15. Its output voltage Utg is determined by the following relation:

thirty

U26 -Ui5Ri K4 / e / (Ki Xa),

(7)

The selective amplifier 27 extracts and amplifies Kg times the ripple of the electrical conductivity to Its output voltage U27 is determined by the following relationship:

U27 -Ui5Ri K5 / cV (Ki Xa).

(eight)

Switch 17 generates a two-pole square-wave signal, which is in phase with the output signal of the controlled oscillator 29, and its amplitude is either Uis or -Uis. The second band-pass filter 13 is also tuned to the frequency of the controlled output voltage.

generator 29. Therefore, its output voltage Ui3 is sinusoidal, which is in phase with voltage U29. The second converter 9, the current, generates a sinusoidal current, r, which is supplied to the terminals of the sensing element of the thermal converter 1 and is determined by the following relationship: 2 U15 / R2, where Ra is the current-current-resistor of the second converter 9. The second differential amplifier 10 measures and amplifies, in Kb, the voltage across the sensing element of the thermal transducer 1, which is connected in a three-conductor manner to eliminate the effect of the resistance of the supply wires. The output voltage Uib of the second differential amplifier 10 is determined by the following relation 1 Uio h RT Kb, where RT is the resistance of the sensitive element of the thermal converter. The third synchronous detector 14 detects the voltage Uyu-. Since the reference signal of the third synchronous detector 14 is in phase with the voltage Uio, the unipolar output voltage Ui of the third synchronous detector is directly proportional to the values of RT. The third low-pass filter 18 filters the voltage Ui4i and its limiting frequency, corresponding to a level of 3 dB, is equal to the upper limiting frequency of the selective amplifier 27. Since the resistance RT of the sensing element of the thermal converter is a non-linear function of RT F (T) from temperature T, then for linearization of this dependence is applied linearizer21, on the swarm entrance of which a reference voltage source 15 is connected to form a piecewise linear approximation. The output voltage HF of the linearizer 21 is determined by the following relationship:

U21-Ul5K6KT () / R2,

(9)

where T is the value of the instantaneous temperature values; T0 is the temperature value from its measurement range; KT is the linearizer conversion factor.

The fourth low pass filter 24 extracts and amplifies CT times the average temperature T. Its output voltage U24 is determined by the following relationship:

U24 U15K6KTK7 (T-T0) / R2.

(YU)

The high pass filter 25 isolates and amplifies in kV the pulsations of temperature T1, and its cutoff frequency is equal to the lower cutoff frequency of the selective amplifier 27. Its output voltage U25 is determined by the following relationship:

and 25 and G5KbKtKvT7N2.

(eleven)

From relations (2), (8) and (11), it can be seen that the output signals of the pulsations of the flow velocity, conductivity and temperature do not depend on each other.

In order to eliminate the mutual influence of the supply poles of the primary converter of the pulsations of the flow velocity, conductivity and temperature, they are fed by common-mode sinusoidal currents. Therefore, there are no beats in the output signals of these converters, which are formed due to the mismatch of the supply currents, either in frequency or in phase.

The installation of a thermal converter coaxially with the axis of symmetry of the primary converter will allow in the middle of the sensitive

In the zone of the primary converter of pulsations of the flow velocity and conductivity, measure also the temperature values. At the same time, on the one hand, the sensitive element of the thermocoupling to increase its speed must be washed from all sides with liquid to eliminate the effect of the dielectric-covered housing, and on the other hand, the thermal convertible must be fully recessed into the housing so that it does not affect on the primary transducer of the flow velocity pulsations. Therefore, the thermal transducer is installed so that its sensitive element is located on the outer surface of the dielectric coating of the first ary converter

As a thermocouple, you can use a thermistor FP 07, the limiting frequency fT of which is determined from the following ratio FT 25.7 V0 5, where V is immeasurable in terms of the average velocity of the primary converter, and at V 1 m / s, fT 25.7 Hz . Because

the boundary wave numbers of the primary converters of pulsations of the flow velocity and conductivity constitute approximately 15.5 1 / m; then for average velocities of movement of the primary transducer of 0–4 m / s, we can assume that the measured parameters of the primary converter of pulsations of flow velocity and conductivity and temperatures have almost identical bands

transmission.

Since the proposed device can measure in one sensitive zone the pulsations of the flow of electrically conductive fluid, conductivity and temperature, by the values of these parameters it is possible to determine for all the conditions encountered in oceanographic studies the salinity pulsations S and the density pulsations by the following ratios;

S «(k, T) l + / 3 () T |; y (k,) - / CCH b (k, T) T; X12)

where a (K. T), / (Ј T), y (Ј, T) and 6 (k, T) are dimensional coefficients calculated by

Claims (1)

the scale of practical salinity and the equation of the state of seawater according to the average values of the specific electrical conductivity, temperature T, which are determined, respectively, by the ratios (7) and (10). Apparatus of the Invention A device for measuring parameters of turbulence of a flow of an electrically conductive fluid according to ed. St. No. 1679338, characterized in that, in order to improve the measurement accuracy and enhance the functionality of the device due to joint measurements in one sensitive area of the flow velocity pulses, conductivity and temperature, a thermal transducer is introduced into it, the second voltage converter is a current, the second differential amplifier, thirds synchronized detector, linearizer, third and fourth low-pass filters, high-pass filter, second band-pass filter and switch, whose input is connected to the source ohm of the reference voltage, the reference input of the switch is connected to the output of the comparator, and the output is connected to d-tl2 input of the second band-pass filter, the output of which is connected to the input of the second voltage-current converter, the outputs of which are connected to the terminals sensor element thermocoupler connected to the inputs of the second differential amplifier, the output of which is connected to the input of the third synchronous detector, the reference input of which is connected to the comparator output, and the output is connected to the input of the third low-pass filter, the output of which is connected to the first input of the linearizer, the second input of which is connected to the reference voltage source, and the output is connected to the inputs of the fourth low-pass filter and high-pass filter whose outputs are the fourth and fifth outputs of the device, respectively, and the thermal converter is installed coaxially with the symmetry axis of the primary converter, while the sensitive element of the thermal converter is located on the outer th primary surface of the dielectric coating converter Bt / ffA  2