RU2582486C1 - Method of determining flow characteristics of hydraulic circuit and device therefor - Google Patents

Abstract

FIELD: transportation; measurement technology.

SUBSTANCE: group of inventions relates to methods and devices used for calculation of capacity of designed hydraulic circuits of transport and dosing systems in chemical, petrochemical, aviation, textile, paint and other industries, particularly to transportation units of adhesive compositions in assembly plants with adhesive joints. Essence of declared method involves experimental determination of average value (ξ_cp) total pressure loss coefficient in channel on local resistances by feed of tap water at room temperature. Watering is performed on path with design structural elements of local resistances and sizes of inner diameters of pipelines by means of multiple portioned dosage of water into measuring containers with constant volumetric flow rate of Q_j at various, stepped variable from maximum to minimum values and maintained during every operation of dosing at constant level values of active head H_j. Consumption Q_j are determined by weighing of measured doses of water on electronic scales. Calculations of parameter ξ_cp and value of flow characteristics of path on parameters of natural liquid, preset range of change of flow rate and actual length of pipelines are performed on personal computer with help of electronic tables Microsoft Excel by formulas Bernoulli equation for steady incompressible fluid flow. Device for determining average value of total pressure loss coefficient on local resistances comprises service tank with tap water, service tank with bubbling and indication tubes with shutoff valves to feed compressed air and filling liquid connected to its lower part of duct with shut-off device at its output, measuring container, system of water pumping from supply tank in feed tank and pneumatic and electronic control unit. System for filling of main tank comprises jet ejector with shutoff valves on air supply line and vacuum line; locking device is made in form of ball valve with double-sided pneumatic drive. Control unit consists of pneumatic pressure regulator and electropneumatic time device, which includes an electronic timer for setting and time of dispensing electricity to air converter and logic pneumatic element NOT, output of which is connected to positive input of pneumatic drive of ball valve, and input is connected to negative input of pneumatic drive and to output of electricity to air converter. Pressure regulator comprises five-membranes comparison element of preset and actual values of pressure at output of bubbling tube is pressure sensor in service tank, pneumatic relay switch of five-membranes comparator output signal to inputs of power amplifiers, outputs of which are connected via gas collecting main to shutoff valve supplying compressed air in service tank. Pressure regulator control panel comprises toggle switch to control set or actual full pressure on reference manometer, toggle switch of pressure feed in feed tank and full pressure setter.

EFFECT: high accuracy and reliability of determining rated flow characteristics of hydraulic circuit at operation on liquid products with different viscosity and possibility of its prediction at variation of specified range of change of flow rate and length forming path sections of pipelines, as well as rapid determination of average (for specified range of change of flow rate) value of total coefficient of active losses in pressure channel on local resistances.

4 cl, 1 dwg

Description

The invention relates to the field of measuring technology and, in particular, relates to the hydraulics section “Calculation of simple pipelines”. The claimed method and device can improve the accuracy and reliability of determining the estimated flow characteristics of the designed (real) hydraulic tract, consisting of a number of local resistances and sections of pipelines with end distribution through a locking device with a drain tip. The invention allows a sufficiently accurate and reliable practice calculation of the flow characteristics of a real path when transporting liquid products of various viscosities along it, as well as predicting the flow characteristics of a path while varying a given range of flow rate and length of individual sections of pipelines. The present invention can be used to calculate the capacity of the designed hydraulic tracts of transport and metering systems in the chemical, petrochemical, aviation, textile, paint and varnish and other industries, in particular, transportation units of adhesive compositions in assembly plants with adhesive joints.

The main task that has to be solved when designing a transport path for liquid products is to determine its throughput (volume flow) Q at various values of the effective pressure N, i.e. its flow characteristic is the function Q = F (H). The proposed method for determining the flow characteristics is based on the analysis of the Bernoulli equation for the steady flow of an incompressible fluid. This equation for a hydraulic path, consisting of several local resistances connected by sections of pipelines of length L _i with an inner diameter d _tj , with end distribution through a drain tip with an inner diameter d _n , has the form:

where f _n = [π (d _n) ^2/4] - the flow cross section of the tip area, g - acceleration due to gravity, λ _i - friction coefficient at i-th pipeline section, ξ - total pressure loss coefficient on the local resistances in the path , which is determined by the design parameters of local resistances and does not depend on the viscosity of the liquid. Given the equality Q = v _n f _n , where v _n is the rate of fluid outflow from the drain tip, equation (1) takes the form:

, где число Рейнольдса Re_i=v_тid_тi/v, v_тi=v_н(d_н/d_тi)² - скорость течения на i-м участке трубопровода. Таким образом, для определения интересующей нас функции Q=F(H) необходимо определить заранее неизвестный параметр ξ.For given values of the parameters v _n , L _i , d _n and d _ti and the known kinematic viscosity of the fluid v, the friction coefficient λ _{i is} easily calculated using the ratios generally accepted in hydraulics. So, for example, for a turbulent flow regime

where the Reynolds number Re _i = v _ti d _ti / v, v _ti = v _n (d _n / d _ti ) ² is the flow velocity in the i-th section of the pipeline. Thus, to determine the function Q = F (H) of interest to us, it is necessary to determine the previously unknown parameter ξ.

There is a method of determining the estimated flow rate characteristics of the hydraulic path in the form of sections of pipelines connected in series through local resistances, which consists in using the Bernoulli equation for steady turbulent fluid motion with preliminary determination of the total pressure loss coefficient at local resistances in the path (ξ) using the reference literature [1. I.I. Kuklevsky and L.G. Subspecies. Collection of tasks in engineering hydraulics. - M.: Mechanical Engineering, 1972, p. 226-233; 2. Idelchik I.E. Handbook of hydraulic resistance. - M.: Mechanical Engineering, 1992. - 672 p.].

The disadvantages of this method is its high complexity and low accuracy due to the large scatter of the reference values of the pressure loss coefficients at individual local resistances, as well as due to their absence for a number of modern designs of hydraulic shut-off and control valves on the liquid transportation line. In addition, the value of the parameter ξ in equations (1) and (2) depends not only on the design parameters of local resistances, but also, to some extent, on the Reynolds number of the flow even in the region of turbulent self-similarity of the flow with respect to the number Re.

There is also a method of determining the coefficient of hydraulic resistance of the tract and a device for its implementation (RU No. 2240525 C1, 20.11.2004), adopted as a prototype.

The known method is implemented by spilling the natural tract in transition full-scale liquid under the pressure of compressed gas, measuring the pressure at the outlet of the tract and measuring the gas pressure in a closed chamber with a fixed volume and determining the cross-sectional area before entering the tract. In this case, before starting the test of the tract, until the chamber is filled with gas, a fixed volume of liquid is poured into the chamber with the formation of a gas-liquid interface, the cross-sectional area of the chamber, the initial height of the gas cushion in the chamber, the initial and variable column height of the liquid in the chamber the entrance to the tract and determine the coefficient of hydraulic resistance by calculation.

The disadvantages of this method is the need to test the path on a full-scale fluid, which requires additional control of changes in its viscosity during the measurement process, as well as the limited use of it on long paths, which requires the possibility of its placement on the test site. The disadvantage of the prototype method is the impossibility of predicting the estimated flow rate characteristics of the path with a variable length of individual sections of the pipelines forming the path due to the impossibility of isolating the pressure loss components from the measurement results, namely: the velocity head of the fluid at the outlet of the path, the pressure loss in the friction path and local resistance. In addition, the disadvantage of this method is its high complexity.

The known prototype device (RU No. 2240525 C1, November 20, 2004) for implementing this method for determining the hydraulic resistance coefficient of a tract comprises a closed chamber of a fixed volume with a gas pressure source, a path holder, a gas pressure meter in the chamber and a shut-off element installed at the outlet of the test path, connected by a flexible connection with the path holder, as well as a fluid source, a liquid level meter in the chamber, a safety valve, a drain tank, a system for pumping liquid from the drain tank to the chamber py when reusing liquid, wherein the closure element is provided with a stopper for removal of gaseous inclusions from the internal cavities path when filling the liquid chamber in front tract by pouring.

The disadvantage of the prototype device is its low accuracy and reliability of determining the estimated flow rate characteristics of the hydraulic path due to the complexity of the measurement method, involving the removal of the dynamic characteristics of the flow of natural fluid. In addition, the known device is characterized by the need to use a large amount of sophisticated instrumentation (sensors and actuators, measuring transducers, computers operating in real time), which reduces the accuracy of measurements.

The objective of the present invention is to improve the accuracy and reliability of determining the flow rate characteristics of the designed path when working on fluids of various viscosities and the possibility of its prediction when varying a given range of flow rates and lengths of the duct sections of the pipelines.

The technical result of the method is to increase the accuracy and reliability of determining the estimated flow rate characteristics of the hydraulic path when transporting liquid products of various viscosities along it and the possibility of predicting it by varying a given range of flow rate and length of the pipeline sections forming the path.

The technical result of the device is the ability to quickly determine the average (for a given range of flow rate) value of the total loss coefficient of the pressure acting in the pressure path at local resistances.

The essence of the proposed method consists in the experimental determination of the parameter ξ included in equations (1) and (2) by repeatedly spilling the path with tap water (with a known kinematic viscosity v _in ) for various values of the effective pressure H = given and maintained at a constant level during each shedding H _j, with further definition by calculation and prediction family consumable path characteristics varying with predetermined values of fluid viscosity range flow changes and length Obra uyuschih path pipe sections.

The technical result of the proposed method for determining the flow rate characteristics of the hydraulic path, consisting of local resistance and sections of pipelines with end distribution through a locking device with a drain tip, by spilling the path with liquid and mathematical processing of the obtained experimental data, is achieved by spilling with tap water at room temperature at tract models with design constructs of local resistances and standard sizes of pipe inner diameters wires through multiple batching water in volumetric container with constant volume flow Q _j at different, stepwise changes from maximum to minimum values and supported during each operation of the dosing constant values of the current head H _j, then calculating the mean value (ξ _cf. ) the total coefficient of pressure loss at local resistances and the recalculation of the flow rate characteristics of the path to the parameters of the natural fluid, a given range of flow rates and lengths of pipelines.

The technical result of the proposed device for determining the average value of the total coefficient of pressure losses at local resistances, containing a supply tank as a source of fluid for channel spillage, a supply tank with a level gauge tube as a level meter, equipped with shut-off valves for supplying compressed air and replenishing fluid with it connected the lower part of the test path with a locking device at its exit, measuring container as a drain tank, a system for pumping liquid from the flow the capacity in the supply tank when reusing liquid, is achieved by the fact that the system of replenishing the supply tank with liquid - tap water - contains a jet ejector with shut-off valves on the pneumatic supply line and vacuum line, the shut-off device is made in the form of a ball valve with a double-sided pneumatic actuator with a negative - " close ”and positive -“ open ”with inlets and with a drain tip, and the supply tank is additionally equipped with a bubbler tube with a power line through a constant dross b, the output of which is connected to the input of the pneumatic-electronic control unit, which consists of a pneumatic pressure regulator and an electro-pneumatic temporary device, containing an electronic timer with a digital indicator and buttons for setting the time and starting the dosing operation, an electro-pneumatic converter with normally open and normally closed pneumatic contacts, whose control input is connected to the timer output, and the logical pneumatic element is NOT, whose output is connected to the positive input nevmoprivoda ball valve and the input - to a negative input to the output of actuator and elektropnevmopreobrazovatelya, which is normally open is connected to pnemokontakt pnevmopitaniya source and pnevmokontakt normally closed to the atmosphere; the pneumatic pressure regulator contains a five-membered comparison element with two positive and two negative inputs, the first and second normally open pneumatic switches, a power amplifier unit, the outputs of which are connected to the shut-off valve for supplying compressed air to the flow tank through the collection manifold and form the control panel for the pressure regulator pneumatic toggle control of a given or actual value of the total pressure in the supply tank, the output of which is connected to the control at the inlet of the first pneumatic relay switch, the full pressure switch and pneumatic toggle switch for supplying pressure to the supply tank, the output of which is connected to the control input of the second pneumatic relay switch, the output of which is connected to the inputs of the power amplifiers, the normally open pneumatic contact of the second pneumatic relay switch communicates with the atmosphere, and its normally closed pneumatic contact is connected to the output of the five-membered element of comparison, the positive inputs of which are connected to the output of the pressure regulator and to the normally open air contact contact of the first pneumorelayer switch, the output of which is connected to an exemplary pressure gauge, and a normally closed pneumatic contact - to the output of the bubbler tube and to the negative inputs of the five-membered comparison element.

The invention is illustrated in the drawing, which shows a diagram of a device that implements a method for determining the flow rate characteristics of the path by preliminary experimental determination of the total pressure loss coefficient at local resistances in the path (ξ) with further determination by calculation and construction of a family of its flow characteristics for liquids of various viscosities and prediction of flow rates characteristics with given variable values of the range of flow rate and length forming the path astkov pipelines.

The device is a system of automated batch dosing of tap water with a control of measuring the dose over time and contains a control object 1 and a pneumatic electronic control unit 2.

The control object 1 contains the following processing equipment:

- a supply tank (PE) 3 with tap water;

- a supply tank (PP) 4 with a sealed lid for working under pressure, equipped with a bubbler tube (BT) 5 and a level gauge tube (UT) 6;

- the test path 7 connected directly to the PP 4 with end distribution through an automatic locking device 8 - a ball valve with double-sided pneumatic actuator, equipped with a drain tip 9; tract 7 consists of sections of pipelines 10 of length l _j and local resistances 11; the measured dose is drained into a measuring container 12;

- jet ejector 13 with shut-off valves 14 on the pneumatic supply line of the ejector and 15 - on the vacuum line, which are used to implement the operation of vacuum (under the action of rarefaction) pumping water from PE 3 to PP 4 with the open position of the shut-off valve 16.

BT 5 performs the function of a full pressure sensor P = p + γ _in H ₁ , where P is the output signal of the BT, p is the overpressure in PP, γ _in = 1 g / cm ³ is the specific gravity of water, H ₁ is the immersion depth of the BT under water level in PP.

The control unit 2 includes a pneumatic proportional pressure regulator P (RD) 17 and a pneumatic electronic temporary device (WU) 18.

RD 17 contains the following functional pneumatic elements: toggle switch 19 "Control P _s / Control P" and a relay 20 for monitoring the pressure gauge 21 of the set (P _s ) (when the switch 19 is turned off) or the actual (P) (when the switch 19 is on) full pressure in the PP, switch 22 "Pressure in the PP" to turn on the supply of compressed air to the PP, a relay 23, a block of power amplifiers 24, a pressure adjuster 25 P _s and a constant choke 26 in the power supply circuit BT. Pneumatic toggle switches 19, 22 and the setter 25 functionally form a taxiway control panel. The functions of the pressure regulator itself are performed by the five-membered element of comparison 27.

RD 17 provides automatic maintenance of a given constant pressure value П _j = p + γ _in H ₁ = П _зj = const in each j-th cycle of spilling (dosing) by pumping compressed air into the PP from amplifiers 24 through a collecting manifold 28 and a shut-off valve 29 , ensuring the constancy of the value of the effective pressure H _j = P _sj / γ _in + H ₂ , and consequently, the flow rate O _j when the shut-off device 8 is open, and thereby creating the possibility of measuring doses over time.

VU 18 contains an electronic timer 30 with a digital indication of the dosing time, set by means of a set of buttons "SET" and "RST", an electro-pneumatic converter 31 and a logical element "NOT" 32.

VU on the command of the operator from the touch button "START" produces a control signal (24 v DC) to switch the locking device 9 to the open position for the time of dispensing water into containers. The dosing time is set between 0-99.99 s with a resolution of 0.01 s.

RD 17, electro-pneumatic transducer 31 and logical element “NOT” 32 are implemented on the element base of the Universal system of industrial pneumatic automation elements (USEPPA) [State system of industrial instruments and automation equipment GSP. Universal system of elements of industrial pneumatic automation USEPPA. Catalog, Volume 5, Issue 1. 1975. 44 pp.].

Power supply of the device’s pneumatic elements is carried out from the pneumatic network through a step-down stabilizer, adjusted to an output pressure of 0.14 MPa. (The stabilizer is not shown in the drawing). The timer is powered by 220 V AC.

The device operates as follows.

Before starting the test of the tract, it is necessary to supply pneumatic and electric power to the control unit 2 (if there is pneumatic supply, the shut-off device 8 is in the initial closed position), fill the PP 4 with water to the upper level, visually controlled by UT 6, and pre-spill the path to displace him air bubbles.

PP 4 is filled under the action of the vacuum generated in the PP by the jet ejector 13 when the valves 14, 15 and 16 are open and the valve 29 is closed. At the end of the PP filling operation, valves 14 and 16 should be closed, and after the pressure in the PP is equalized to atmospheric and valve 15.

The path is preliminarily spilled under the influence of the hydrostatic pressure of the water column in the PP with the closed positions of the valves 14 and 16 and the open positions of the valve 29 and the locking device 8. To implement the pouring operation, set the container 12 to the filling position using the “SET” and “RST” buttons , set the pre-spill time on the digital timer display and start the spill operation with the "START" button. The preliminary shedding time is selected experimentally and should be sufficient to completely remove air bubbles from the tract. The proper quality of the spill is established visually by the continuity of the stream of water at the outlet of the drain tip. At the end of the preliminary shedding, it is necessary to close valve 15.

The working cycle of the tract tests, the purpose of which is to determine the average value of the total head loss coefficient at its local resistances, consists in its multiple successive spillings with various constant values (starting from the maximum) of the effective head H _j = P _{s, j} / γ _in + H ₂ = const. The pressures P _{s, j are} adjusted by the adjuster 25 and controlled by the pressure gauge 21. To implement pouring (batching) operations, the measuring container 12 should be set to the filling position, the regulator 25 should be adjusted by the pressure gauge 21 to the next dose setting pressure - P _{s, j} and the toggle switch 22 for supplying pressure to the PP 4. The pressure set in the PP is controlled by a pressure gauge 21 with the toggle switch 19 on. When the equality P _j = P _{s, j} is reached _{, the} device is ready for the batching operation. Before starting the cycle of dosing operations, you should install the container on an electronic balance (the balance is not shown in the drawing) and reset their readings. Next, on the digital display of timer 30, you should set the dispensing time corresponding to the tare capacity, the set pressure value P _{s, j} and the upper limit of the weight measurement on the electronic balance (this time is selected experimentally so as to avoid overfilling of the container). The dosing operation is carried out by touching the “START” touch button on the timer. The measured dose is manually poured from the measuring container 12 into PE 3.

The described cycle of dosing operations can be repeated after replenishment of PP 4 using the ejector 13.

At the end of the operation of the channel spill, turn off the toggle switch 22 and open the valve 15 to bleed air from the PP 4 through the flow chamber of the ejector 13; after complete bleeding of air, press the “START” button on the timer to empty the tract, and after removing water from the tract, turn off the power to the timer and turn off the pneumatic supply to the control unit.

As a result of the implementation of the described cycle of pouring operations, in accordance with equation (1) for each value of the effective pressure H _j using the Microsoft Exel spreadsheets, the following parameters are successively calculated:

- volumetric flow rate - Q _j [cm ³ / s] = V _j / t _j corresponding to the pressure H _j , where V _j [cm ³ ] is the dose volume recorded by weighing on an electronic balance, t _j [s] is the dosing time , j = 1, 2 ... n, n≈20 is the number of spills in this test cycle;

- the rate of flow of water from the drain tip - v _nj [cm / s] = Q _j / f _n ;

- water flow rates in separate (ix) sections of pipelines - v _{ti, j} [cm / s] = v _nj (d _n / d _ti ) ² ;

- Reynolds number of the water flow pipes at separate sites - Re _{i, j} = v _{Ti, j} d _Ti / v = 100v _{in Ti, j} d _Ti (v _s = 10 ^-2 cm ² / s);

;- friction coefficients in individual sections of pipelines -

;

;- pressure loss at the outlet of the discharge tip -

;

- friction pressure loss in individual sections of the pipelines - h _{ti, j} [cm] = λ _{i, j} (l _i / d _ti ) (d _n / d _ti ) ⁴ ;

- total friction head loss in the tract -

- total pressure loss at local resistances in the path - h _мj [cm] = H _j -h _нj -h _тj ;

;- total pressure loss coefficient at local resistances -

;

.- the average value of the total coefficient of pressure losses at local resistances -

.

Further, using the average value of the total head loss coefficient at local resistances (ξ _cp ) calculated by the above method and the design values of the internal diameter d _{n of the} drain tip and the lengths L _i of the pipeline sections, the calculated values (H _{p, k} ) of the effective pressure for the given design values (Q _{s, k} ) of the required range of variation in flow rate and viscosity v of the natural fluid.

These calculations are carried out as before, using Microsoft Excel spreadsheets. To do this, set a number of flow rates Q _{s, k} (k = 1, 2 ... m) from the minimum - Q _{s, 1} = Q _{s, min} to the maximum - Q _{s, m} = Q _{s, max} from the range of change required by the project and sequentially calculate the parameters included in equation (1):

- the rate of flow of fluid from the drain tip -

;- pressure loss at the outlet of the drain tip -

;

- flow rates at separate (ix) sections of pipelines - v _{ti, k} [cm / s] = v _{n, k} (d _n / d _ti ) ² ;

- Reynolds numbers in individual sections of the pipelines - Re _{i, k} = v _{ti, k} d _ti / v;

;- friction coefficients in individual sections of pipelines -

;

- friction pressure loss in individual sections of the pipelines - h _ti , _k [cm] = λ _{i, k} (L _i / d _ti ) (d _n / d _ti ) ⁴ ;

;- total friction head loss in the tract -

;

- total pressure loss at local resistances in the path - h _{m, k} [cm] = ξ _cp h _{n, k} ;

- the calculated values of the effective pressure - H _{p, k} [cm] = h _{n, k} + h _{t, k} + h _{m, k} .

Thus, the proposed method and device allows in laboratory conditions to quickly and with a high degree of reliability to obtain points Q _{s, k} flow characteristics Q _{s, k} = F (H _{p, k} ) of the designed tract for liquids of various viscosities in varying ranges of flow rates, and also with a variable length forming the tract sections of pipelines.

In addition, using the spreadsheets of Microsoft Exel and the Advanced Grapher program that is additionally available on the Internet, the resulting flow rate characteristics of the path (with a sufficient number of points) obtained by the method described above can be approximated by automatic regression analysis and presented graphically according to equation (1) in the form of functions Q = F (H). This allows us to predict the family of flow characteristics of the path with variable physical parameters of the natural fluid (specific gravity γ and kinematic viscosity v) and variable length of the pipeline sections forming the path.

Claims (4)

1. The method of determining the flow rate characteristics of the hydraulic path, consisting of local resistance and sections of pipelines with end distribution through a locking device with a drain tip, by spilling the path with liquid and mathematical processing of the obtained experimental data, characterized in that the spilling is performed with tap water at room temperature on the model a path with design constructs of local resistances and sizes of internal diameters of pipelines, by means of multiple on portioned dosing of water into a measuring container with a constant volumetric flow rate Q _j at various stepwise varying from maximum to minimum values and supported during each dispensing operation at a constant level of the effective pressure H _j , followed by calculation of the average value (ξ _cf ) of the total coefficient pressure losses at local resistances and recalculation of the flow rate characteristics of the path to the parameters of the natural fluid, a given range of flow rate changes and the actual length of the pipelines. 2. The method according to p. 1, characterized in that the calculation of the average value (ξ _cf ) of the total coefficient of pressure loss at local resistances is performed on a computer using spreadsheets of Microsoft Exel in the following sequence according to the formulas:
- volumetric flow rate - Q _j [cm ³ / s] = V _j / t _j corresponding to the pressure H _j , where V _j [cm ³ ] is the dose volume recorded by weighing on an electronic balance, t _j [c] is the dosing time , j = 1,2 ... n, n≈20 is the number of spills in a given test cycle;
- flow area of the drain tip -

- the rate of flow of water from the drain tip - v _nj [cm / s] = Q _j / f _n ;
- water flow rates in separate (ix) sections of pipelines - v _{ti, j} [cm / s] = v _nj (d _n / d _ti ) ² , where d _n is the internal diameter of the drain tip, d _ti is the internal section of the pipeline with a length l _i;
- Reynolds number of the water flow pipes at separate sites - Re _{i, j} = v _{Ti, j} d _Ti / v = 100v _{in Ti, j} d _Ti (v _s = 10 ^-2 cm ² / s - the kinematic viscosity of water at room temperature );
- friction coefficients in individual sections of pipelines -

- pressure loss at the outlet of the drain tip -

- friction pressure loss in individual sections of the pipelines - h _{ti, j} [cm] = λ _{i, j} (l _i / d _ti ) (d _n / d _ti ) ⁴ ;
- total friction head loss in the tract -

- total pressure loss at local resistances in the path - h _мj [cm] = H _j -h _нj -h _тj ;
- total pressure loss coefficient at local resistances -

- the average value of the total coefficient of pressure losses at local resistances -

3. The method according to p. 1, characterized in that to recalculate the flow rate characteristics of the path to the parameters of the natural fluid and the actual lengths of the pipelines set a number of flow rates Q _{s, k} (k = 1.2 ... m) from the minimum - Q _{s, l} = Q _{s, min} to the maximum
- Q _{s, m} = Q _{s, max} from a given range of its change and calculate the corresponding calculated values of the effective pressure - N _{p, k} in the sequence indicated below by the formulas:
- the rate of flow of fluid from the drain tip -

- pressure loss at the outlet of the drain tip -

- flow rates in separate (ix) sections of pipelines - v _{ti, k} [cm / s] = v _{n, k} (d _n / d _ti ) ² ;
- Reynolds numbers in individual sections of the pipelines - Re _{i, k} = v _{ti, k} d _ti / v;
- friction coefficients in individual sections of pipelines -

- friction pressure loss in individual sections of the pipelines -h _{ti, k} [cm] = λ _{i, k} (L _i / d _ti ) (d _n / d _ti ) ⁴ ;
- total friction head loss in the tract -

- total pressure loss at local resistances in the path - h _{m, k} [cm] = ξ _cp h _{n, k} ;
- the calculated values of the effective pressure - N _{p, k} [cm] = h _{n, k} + h _{t, k} + h _{m, k} . 4. A device for determining the average value of the total coefficient of pressure loss at local resistances, containing a supply tank as a source of fluid for channel spillage, a supply tank with a level gauge tube as a level meter, equipped with shut-off valves for supplying compressed air and replenishing fluid with a lower one parts of the test path with a locking device at its outlet, a measuring container as a drain tank, a system for pumping liquid from a supply tank to a supply tank, etc. and reuse of liquid, characterized in that the system of replenishing the supply tank with liquid - tap water - contains a jet ejector with shut-off valves on the pneumatic supply line and vacuum line, the shut-off device is made in the form of a ball valve with a double-sided pneumatic actuator with a negative “close” and positive “Open” with entrances and with a drain tip, and the supply tank is additionally equipped with a bubbler tube with a power line through a constant choke, the output of which is connected to the input to a pneumatic-electronic control unit consisting of a pneumatic pressure regulator and an electro-pneumatic temporary device, comprising an electronic timer with a digital indicator and buttons for setting the time and starting the dosing operation, an electro-pneumatic converter with normally open and normally closed pneumatic contacts, the control input of which is connected to the timer output, and logical pneumatic element NOT, the output of which is connected to the positive input of the pneumatic actuator ball valve, and the input - to the negative input of the pneumatic actuator and to the output of the electro-pneumatic converter, the normally open pneumatic contact of which is connected to the pneumatic supply, and the normally closed pneumatic contact is connected to the atmosphere; the pneumatic pressure regulator contains a five-membered comparison element with two positive and two negative inputs, the first and second normally open pneumatic switches, a power amplifier unit, the outputs of which are connected to the shut-off valve for supplying compressed air to the flow tank through the collection manifold and form the control panel for the pressure regulator pneumatic toggle control of a given or actual value of the total pressure in the supply tank, the output of which is connected to the control at the inlet of the first pneumatic relay switch, the full pressure switch and pneumatic toggle switch for supplying pressure to the supply tank, the output of which is connected to the control input of the second pneumatic relay switch, the output of which is connected to the inputs of the power amplifiers, the normally open pneumatic contact of the second pneumatic relay switch communicates with the atmosphere, and its normally closed pneumatic contact is connected to the output of the five-membered element of comparison, the positive inputs of which are connected to the output of the pressure regulator and to the normally open air contact contact of the first pneumorelayer switch, the output of which is connected to an exemplary pressure gauge, and a normally closed pneumatic contact - to the output of the bubbler tube and to the negative inputs of the five-membered comparison element.

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