CN109489745B - Flow measuring method based on data iteration - Google Patents
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- CN109489745B CN109489745B CN201811407993.9A CN201811407993A CN109489745B CN 109489745 B CN109489745 B CN 109489745B CN 201811407993 A CN201811407993 A CN 201811407993A CN 109489745 B CN109489745 B CN 109489745B
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- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
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Abstract
The invention discloses a flow measuring method based on data iteration, which comprises the following steps: (S1) setting a plurality of measuring points in the measuring tube section; (S2) measuring and calculating the flow rate U at each measuring pointiAnd a pressure value FiRecording the coordinate P of each measuring point in the physical space of the measuring pipe sectioni(xpi，ypi，zpi) (ii) a (S3) determining a polyhedron composed of adjacent measuring points as a minimum fluid control unit according to the adjacency relation of the measuring points; (S4) calculating a surface flow rate and a surface pressure of the contact surfaces of the two adjacent minimum fluid control units; (S5) substituting the obtained surface flow velocity and surface pressure into a fluid momentum conservation equation and a fluid mass conservation equation, iteratively revising the surface flow velocity and the surface pressure until the fluid momentum conservation and the fluid mass conservation are simultaneously met, and carrying out numerical calculation convergence to obtain a continuous flow field of the measuring pipe section so as to realize flow measurement of the measuring pipe section. The invention enlarges the measuring range in the measuring section and improves the flow metering precision.
Description
Technical Field
The present invention relates to the field of fluid flow measurement technology, and more particularly, to a flow measurement method based on data iteration.
Background
At present, the types of water meters widely used mainly include mechanical water meters, ultrasonic water meters, electromagnetic water meters and the like, but the water meters have certain defects in practical use due to the limitation of the metering principle.
The mechanical water meter utilizes water flow to push a water meter impeller to rotate, and the water consumption of a user is obtained by integrating the water flow and the counter. The mechanical water meter has mature technology and low cost, but has a complex structure, large pressure loss and large error at a small flow.
The ultrasonic water meter calculates the average flow velocity on the sound channel by using the velocity difference of the sound wave propagating in the forward water flow direction and the backward water flow direction, and obtains the surface average velocity through integration so as to obtain the volume flow. The ultrasonic water meter has simple structure, low pressure loss and small kinetic flow. However, the ultrasonic water meter is greatly influenced by the use environment and installation conditions, and particularly, when a transverse velocity or vortex flow exists in a measurement section, the velocity distribution on a sound channel is distorted, so that the measurement accuracy is influenced.
The electromagnetic water meter measures flow by utilizing Faraday's law of electromagnetic induction, adopts full electronic design, has no mechanical moving parts, has small pressure loss and can realize wide range ratio. However, when the electromagnetic water meter works, the exciting current is large, the battery endurance is poor, the flow change response is slow, the environmental adaptability is weak, and the electromagnetic water meter is easy to be subjected to electromagnetic interference.
Disclosure of Invention
The invention aims to provide a flow metering method based on data iteration, which enlarges the measuring range in a measuring section and improves the metering precision.
In order to achieve the above object, the present invention provides a data iteration-based flow measurement method, which includes the following steps:
(S1) setting a plurality of measuring points in the measuring tube section;
(S2) measuring and calculating the flow rate U at each measuring pointiAnd a pressure value FiRecording the coordinate P of each measuring point in the physical space of the measuring pipe sectioni(xpi，ypi，zpi)；
(S3) determining a polyhedron composed of adjacent measuring points as a minimum fluid control unit according to the adjacency relation of the measuring points;
(S4) calculating the surface flow velocity of the contact surface of the two adjacent minimum fluid control units, and calculating the surface pressure of the contact surface of the two adjacent minimum fluid control units;
(S5) substituting the obtained surface flow velocity and surface pressure into a fluid momentum conservation equation and a fluid mass conservation equation, iteratively revising the surface flow velocity and the surface pressure until the fluid momentum conservation and the fluid mass conservation are simultaneously met, and carrying out numerical calculation convergence to obtain a continuous flow field of the measuring pipe section so as to realize flow measurement of the measuring pipe section.
According to a preferred embodiment of the invention, said minimum fluid control unit is a tetrahedron or a hexahedron consisting of adjacent measurement points.
According to the preferred embodiment of the present invention, in the step (S2), the flow rate U at each measurement pointiThe measuring and calculating steps are as follows:
(S21) fixedly installing a three-dimensional net rack having a plurality of grid nodes in the measurement pipe section, and fixedly installing a hot wire probe at each grid node of the three-dimensional net rack with the grid nodes as measurement points;
(S22) heating the hot wire probe with the heating device output voltage E so that the hot wire probe maintains a constant temperature in the fluid;
(S23) a flow rate U at each measurement point is calculated by establishing a relation between the output voltage E and the flow rate U at each measurement point:
E2＝A+B·Um
where E is the output voltage of the heating device and U is the flow rate at each measurement point, where A, B and m are calibration constants, calibrated in a measurement pipe section where the flow rate is known.
Preferably, the electrical signal output by the heating device is compensated for amplification before the output voltage E is related to the flow velocity U at each measurement point, thereby improving the accuracy of the data.
According to a preferred embodiment of the present invention, in the step (S2), the pressure value F at each measurement pointiThe measuring and calculating steps are as follows:
fixedly arranging a three-dimensional net rack with a plurality of grid nodes in a measuring pipe section, taking the grid nodes as measuring points, fixedly arranging a miniature water pressure sensor at each grid node of the three-dimensional net rack, and detecting and acquiring pressure values F at each measuring point through the miniature water pressure sensorsi。
Preferably, when the three-dimensional net rack is arranged, the side provided with the micro water pressure sensor faces the coming path direction of the fluid.
According to the preferred embodiment of the present invention, in the step (S4), the specific steps of calculating the surface flow rate and the surface pressure of the contact surfaces of the two adjacent minimum fluid control units are as follows:
calculating the flow rate U of each measurement point in the minimum fluid control unitiTaking the average value of the body flow velocity of two adjacent minimum fluid control units as the surface flow velocity of the contact surfaces of the two adjacent minimum fluid control units;
calculating pressure values F of each measuring point in the minimum fluid control unitiTaking the average value as the body pressure of the minimum fluid control unit, and taking two adjacent minimum fluid controlsAnd taking the average value of the body pressure of the manufacturing units as the surface pressure of the contact surfaces of two adjacent minimum fluid control units.
The above and other objects, features, and advantages of the present invention will become further apparent from the following detailed description, the accompanying drawings, and the appended claims.
Drawings
FIG. 1 is a schematic flow diagram of a flow measurement method in accordance with a preferred embodiment of the present invention;
fig. 2 is a schematic cross-sectional structure of a spatial net mount according to a preferred embodiment of the present invention;
fig. 3 is another schematic cross-sectional structure of a spatial net mount according to a preferred embodiment of the present invention;
fig. 4 is another schematic cross-sectional structure of a spatial net mount according to a preferred embodiment of the present invention;
fig. 5 is another schematic cross-sectional structure of a spatial net mount according to a preferred embodiment of the present invention;
FIG. 6 is a schematic view illustrating a use state of the spatial net mount according to the preferred embodiment of the present invention, which shows that the spatial net mount is fixedly provided within a measurement pipe section;
FIG. 7 is a schematic view of another usage state of the spatial net mount according to the preferred embodiment of the present invention, showing the spatial net mount fixedly disposed within a measurement pipe section;
fig. 8 is a perspective view schematically illustrating a minimum fluid control unit according to a preferred embodiment of the present invention.
Detailed Description
The invention is further described with reference to the drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.
The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.
It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced devices or components must be in a particular orientation, constructed and operated in a particular orientation, and thus the above terms are not to be construed as limiting the present invention.
It is understood that the terms "a" and "an" should be interpreted as meaning that a number of one element or element is one in one embodiment, while a number of other elements is one in another embodiment, and the terms "a" and "an" should not be interpreted as limiting the number.
Referring to fig. 1-8 of the drawings, a data iteration-based flow metering method in accordance with a preferred embodiment of the present invention will be set forth in the description that follows. As shown in fig. 1, the data iteration-based flow measurement method includes the following steps:
(S1) setting a plurality of measuring points in the measuring tube section;
(S2) measuring and calculating the flow rate U at each measuring pointiAnd a pressure value FiRecording the coordinate P of each measuring point in the physical space of the measuring pipe sectioni(xpi，ypi，zpi)；
(S3) determining a polyhedron composed of adjacent measuring points as a minimum fluid control unit according to the adjacency relation of the measuring points;
(S4) calculating the surface flow velocity of the contact surface of the two adjacent minimum fluid control units, and calculating the surface pressure of the contact surface of the two adjacent minimum fluid control units;
(S5) substituting the obtained surface flow velocity and surface pressure into a fluid momentum conservation equation and a fluid mass conservation equation, iteratively revising the surface flow velocity and the surface pressure until the fluid momentum conservation and the fluid mass conservation are simultaneously met, and carrying out numerical calculation convergence to obtain a continuous flow field of the measuring pipe section so as to realize flow measurement of the measuring pipe section.
Preferably, the minimum fluid control unit is a tetrahedron or hexahedron composed of adjacent measurement points.
Specifically, in the step (S2), the flow rate U at each measurement pointiThe measuring and calculating steps are as follows:
(S21) fixedly installing a three-dimensional net rack having a plurality of grid nodes in the measurement pipe section, and fixedly installing a hot wire probe at each grid node of the three-dimensional net rack with the grid nodes as measurement points;
(S22) heating the hot wire probe with the heating device output voltage E so that the hot wire probe maintains a constant temperature in the fluid;
(S23) a flow rate U at each measurement point is calculated by establishing a relation between the output voltage E and the flow rate U at each measurement point:
E2＝A+B·Um
where E is the output voltage of the heating device and U is the flow rate at each measurement point, where A, B and m are calibration constants, calibrated in a measurement pipe section where the flow rate is known.
Preferably, the electrical signal output by the heating device is compensated for amplification before the output voltage E is related to the flow velocity U at each measurement point, thereby improving the accuracy of the data.
It is worth mentioning that the hot wire probe should be arranged on the water-facing side of the three-dimensional net rack to reduce the influence of the three-dimensional net rack on the water flow. In addition, a certain distance should be kept between different grid nodes to reduce interference of water flow disturbance caused by an upstream grid node to measurement of a hot wire probe of a downstream grid node, and meanwhile, certain grid node density should be ensured to improve measurement accuracy.
When a fluid passes through the hot wire probe at a certain flow rate, part of the heat is taken away, and in order to keep the temperature of the hot wire probe constant, the voltage output by the heating device to the hot wire probe changes correspondingly, so that a relation between the output voltage E and the flow rate U at each measuring point can be established in the measuring tube segment with a known flow rate.
The three-dimensional net rack is formed by connecting metal wires with certain strength according to a certain rule, as shown in fig. 2 to 5, the arrangement mode of the grid nodes can be structured grids or unstructured grids used in hydrodynamics. As is easily understood by the technical personnel in the field, the structured grid is composed of hexahedral units, the adjacency between grid nodes is orderly and regular, and the iterative computation efficiency is high; the unstructured grid is composed of units such as tetrahedrons, triangular prisms or pyramids, the adjacent relation between grid nodes is disordered and irregular, each grid node can have different adjacent grid numbers, and the adaptability to the shape of a pipe section is strong. The arrangement mode and the density of the grid nodes can be realized by grid division software and verified by CFD simulation.
Fig. 2 to 5 are schematic cross-sectional views of three-dimensional net racks with different grid node arrangements, as an example. It should be noted that the cross section in the present invention is a cross section of the measurement pipe section, that is, the cross section in the present invention is a cross section perpendicular to the flow direction of the measurement pipe section. Fig. 2 shows a full tetrahedral mesh (single face is triangular), fig. 3 shows a full hexahedral mesh (single face is quadrilateral), fig. 4 shows a full hexahedral "o" type mesh, and fig. 5 shows a tetrahedral hexahedral mixed mesh.
Preferably, the diameter of the metal wires forming the three-dimensional net rack is 10-100 microns, so as to reduce the influence of the three-dimensional net rack on the fluid. It is easily understood by those skilled in the art that in other possible preferred embodiments of the three-dimensional net rack of the present invention, the three-dimensional net rack may be made of other materials with certain strength, such as, but not limited to, carbon fiber materials.
The hot wire probe is connected to the heating device through a conducting wire, and the metal wires among grid nodes are used for fixing the conducting wire. Preferably, the hot wire probe and the lead are hermetically fixed on the three-dimensional net frame through a quartz coating so as to maintain insulation and stability.
Preferably, the hot wire probe is a platinum wire or a tungsten wire, so that the sensitivity is high, and accurate measurement can be realized under the condition of low flow. However, it is easily understood by those skilled in the art that the kind of the hot wire probe is not limited in the flow rate metering device of the present invention, and in other possible embodiments of the present invention, the hot wire probe may be implemented to be made of other metals having good thermal conductivity, such as but not limited to copper, aluminum, sodium, etc.
Preferably, the hot wire probe has a length of 0.4 mm to 0.6 mm and a diameter of 9 micrometers to 11 micrometers.
As shown in fig. 6 and 7, which illustrate the use state that the three-dimensional net rack is fixedly arranged in the measuring pipe section, and the measuring pipe section is suitable for flowing gas or liquid. Each grid node of the three-dimensional net rack is provided with a hot wire probe, so that a micro detection probe bundle covering a section of flow space is formed, the surface velocity distribution of fluid in a measuring pipe section is obtained through numerical algorithm fitting according to the flow velocity, the pressure value and the space position of each grid node, the volume flow is obtained, and the accurate measurement of liquid and gas is realized.
Compared with an ultrasonic water meter, the flow metering method based on data iteration has the advantages that through gridding point distribution, the total measuring points can cover the whole measuring range of the measuring pipe section, errors caused by obtaining the surface speed through finite sound channel linear speed integral are avoided, and the metering precision is improved. In addition, the gridding distribution can realize real-time detection of radial and axial spatial velocity distribution of the measuring pipe section and cover a certain measuring length, so that the transverse velocity and vortex flow existing in a flow field can be captured in real time, and even if a flow blocking piece exists at the front end of the measuring pipe section, accurate measurement of flow can still be realized.
Further, in the step (S2), the pressure value F at each measurement pointiThe measuring and calculating steps are as follows:
a three-dimensional net rack with a plurality of grid nodes is fixedly arranged in a measuring pipe section, and the grid nodes are used as measuring pointsFixedly arranging a miniature water pressure sensor at each grid node of the three-dimensional net rack, and detecting and acquiring pressure values F at each measuring point by the miniature water pressure sensorsi。
The Micro water pressure sensor is manufactured into a pressure sensitive chip with the size within 1mm by adopting the MEMS (Micro Electro Mechanical Systems) Micro electromechanical system technology through a silicon body Micro machining method, and is packaged into a pressure probe. Because the miniature water pressure sensor has extremely small overall dimension of the sensor, the miniature water pressure sensor has extremely small disturbance and influence on a flow field, and is widely used in fluid mechanics and wind tunnel tests.
Preferably, when the three-dimensional net rack is arranged, the side provided with the micro water pressure sensor faces the coming path direction of the fluid.
According to the preferred embodiment of the present invention, in the step (S4), the specific steps of calculating the surface flow rate and the surface pressure of the contact surfaces of the two adjacent minimum fluid control units are as follows:
calculating the flow rate U of each measurement point in the minimum fluid control unitiTaking the average value of the body flow velocity of two adjacent minimum fluid control units as the surface flow velocity of the contact surfaces of the two adjacent minimum fluid control units;
calculating pressure values F of each measuring point in the minimum fluid control unitiThe average value of the pressure of the minimum fluid control unit is taken as the pressure of the minimum fluid control unit, and the average value of the pressure of the two adjacent minimum fluid control units is taken as the surface pressure of the contact surface of the two adjacent minimum fluid control units.
Illustratively, as shown in fig. 8, taking two adjacent hexahedral minimum fluid control units (8 measurement points) as an example, the flow rates of the measurement points 1-12 are obtained through steps (S21) - (S23), and then the bulk flow rate of the front minimum fluid control unit is the average of the flow rates at the measurement points 1, 2, 3, 4, 5, 6, 7, 8, the bulk flow rate of the rear minimum fluid control unit is the average of the flow rates at the measurement points 4, 5, 6, 7, 8, 9, 10, 11, 12, and the surface flow rate of the contact surface of the two adjacent minimum fluid control units consisting of the measurement points 5, 6, 7, 8 is the average of the bulk flow rates of the two adjacent minimum fluid control units.
Similarly, referring to the calculation step of the surface flow velocity, the average value of the body pressures of the two adjacent minimum fluid control units is taken as the surface pressure of the contact surface of the two adjacent minimum fluid control units.
Specifically, in the step (S5), the obtained surface flow velocity and surface pressure are substituted into the fluid momentum conservation equation, and the surface flux of the contact surface of each minimum fluid control unit, that is, the flow passing through the contact surface of each minimum fluid control unit, is obtained by solving;
substituting the obtained surface flux into a fluid mass conservation equation, iteratively revising the surface flow rate and the surface pressure until the surface flux accords with the fluid mass conservation equation, and carrying out numerical calculation convergence;
and after calculation convergence, obtaining a continuous flow field of the measuring pipe section, namely the flow velocity and the pressure value of any time and any place in the flow field, thereby realizing the flow measurement of the measuring pipe section.
Since the obtained surface flow velocity and surface pressure on the contact surface of the minimum fluid control unit are both mean values, the surface flux obtained by solving the fluid momentum conservation equation by using the surface flow velocity and the surface pressure cannot meet the fluid mass conservation equation, and the surface flow velocity and the surface pressure need to be iteratively revised until the surface flux meets the fluid mass conservation equation.
The differential form of the conservation of momentum equation for a fluid is as follows:
wherein the content of the first and second substances,
representing the rate of change of momentum with time;
horizontal convection (entrainment of momentum);
representing volumetric forces, including gravity and buoyancy;
representing the force acting on the minimum fluid control unit due to pressure and stress gradients. The physical meaning of conservation of fluid momentum is that the rate of change of fluid momentum in the smallest fluid control cell is equal to the sum of the resultant stress and all volumetric forces acting on the smallest fluid control cell face.
The differential form of the conservation of mass equation for a fluid is as follows:
wherein the content of the first and second substances,
is the rate of change of mass over time in the minimum fluid control unit;
representing the mass convection (coupling of the mass) of the smallest fluid control unit. The physical meaning of conservation of fluid mass is that the amount of fluid mass increase in the minimum fluid control unit is equal to the difference in fluid mass flowing into and out of the minimum fluid control unit.
In the flow measuring method based on data iteration provided by the invention, the density of the fluid is known, and the surface flow velocity on the minimum fluid control single-surface contact surface can be obtained through the steps, namely, the flow (surface flux) flowing through each contact surface can be obtained, the surface flux is substituted into a fluid mass conservation equation, and if the surface flux is not conserved, the surface flow velocity and the surface pressure can be corrected according to the magnitude relation between the predicted quantity and the target value until the surface flux accords with the fluid mass conservation equation.
In the conservation of momentum equation, the measured surface flow velocity and surface pressure are brought into the conservation of momentum equation (where τijThe shear stress is obtained by velocity gradient and fluid viscosity coefficient), if the shear stress can not be conserved, the surface flow velocity and the surface pressure are corrected according to the target value, and through continuous iteration, when the corrected surface flow velocity and the corrected surface pressure can ensure the conservation of mass and momentum, namelyConvergence is determined.
The continuous flow field of the measuring pipe section is obtained after the operation is converged, namely the flow velocity and the pressure value at any time and any place in the flow field are known, so that the flow value in the measuring pipe section at any time can be obtained, and the purpose of flow measurement is achieved.
It is readily understood by those skilled in the art that mathematical models describing the physical phenomena of fluids are mostly differential equations, such as conservation of mass, conservation of momentum, and conservation of energy equations for fluids. The computer cannot directly solve such differential equations, and the computer usually needs to convert such differential equations into algebraic equations by using a mathematical method, and obtain the solutions of the original differential equations by solving the algebraic equations. The transformation method may use a finite difference method, a finite element method, a finite volume method, or the like.
To achieve this transformation, it is necessary to introduce grid nodes, which transform continuous space and time into discrete space and time, so as to obtain algebraic equations at each grid cell or grid node. The algebraic equations on all grid nodes are integrated together to form an algebraic equation system on the whole calculation domain, and the physical quantity on each grid unit or grid node can be obtained by solving the equation system. The physical quantity obtained by solving the algebraic equation system is discrete, and in order to obtain the physical quantity distribution between nodes or units, an interpolation method is adopted to obtain approximately continuous physical quantity distribution. Very accurate computation results can be obtained by interpolation when the computation grid or computation time interval is sufficiently small.
However, when the engineering problem is calculated, the number of grids is huge, and the problem that the algebraic equation system is solved by adopting a direct method is very large, so that the iterative method is usually adopted for solving the large-number equation systems such as the engineering problem. The iterative method utilizes the sparse characteristic of the coefficient matrix of the equation set to convert the problem into the construction of an infinite iteration sequence to gradually approximate the solution of the equation set, has the advantages of simple method, small required calculation space, easy parallelism and the like, and has certain advantage in convergence speed.
It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.
Claims (7)
1. A data iteration-based flow metering method, comprising the steps of:
s1: arranging a plurality of measuring points in the measuring pipe section;
s2: measuring and calculating the flow rate U at each measuring pointiAnd a pressure value FiRecording the coordinate P of each measuring point in the physical space of the measuring pipe sectioni(xpi，ypi，zpi)；
S3, determining a polyhedron formed by adjacent measuring points as a minimum fluid control unit according to the adjacency relation of the measuring points;
s4: calculating the average value of the flow velocity Ui of each measuring point in the minimum fluid control unit, taking the average value as the body flow velocity of the minimum fluid control unit, and taking the average value of the body flow velocities of two adjacent minimum fluid control units as the surface flow velocity of the contact surface of the two adjacent minimum fluid control units; calculating the average value of pressure values Fi of each measuring point in the minimum fluid control unit, taking the average value as the body pressure of the minimum fluid control unit, and taking the average value of the body pressures of two adjacent minimum fluid control units as the surface pressure of the contact surfaces of the two adjacent minimum fluid control units;
s5: and substituting the obtained surface flow velocity and surface pressure into a fluid momentum conservation equation and a fluid mass conservation equation, iteratively revising the surface flow velocity and the surface pressure until the momentum conservation and the mass conservation are simultaneously met, and converging the numerical calculation to obtain a continuous flow field of the measuring pipe section so as to realize the flow measurement of the measuring pipe section.
2. The data iteration-based flow metering method of claim 1 wherein the minimum flow control unit is a tetrahedron or hexahedron consisting of adjacent measurement points.
3. The data iteration-based flow metering method of claim 1 or 2, wherein in step S2, the flow rate U at each measurement pointiThe measuring and calculating steps are as follows:
s21, fixedly arranging a three-dimensional net rack with a plurality of grid nodes in the measuring pipe section, taking the grid nodes as measuring points, and fixedly arranging a hot wire probe at each grid node of the three-dimensional net rack;
s22, heating the hot wire probe by using the output voltage E of the heating device so that the hot wire probe keeps constant temperature in the fluid;
s23, establishing a relation between the output voltage E and the flow speed U at each measuring point, and calculating the flow speed U at each measuring point:
E2＝A+B·Um
where E is the output voltage of the heating device and U is the flow rate at each measurement point, where A, B and m are calibration constants, calibrated in a measurement pipe section where the flow rate is known.
4. The data iteration-based flow metering method of claim 3, wherein the electrical signal output by the heating device is compensated for amplification before the output voltage E is related to the flow rate U at each measurement point.
5. The data iteration-based flow metering method according to claim 3, characterized in that, when the three-dimensional net rack is arranged, the side provided with the hot wire probe is directed to the coming path direction of the fluid.
6. The data iteration-based flow metering method of claim 1 or 2, wherein in step S2, a pressure value F at each measurement pointiThe measuring and calculating steps are as follows:
fixedly arranging a three-dimensional net rack with a plurality of grid nodes in a measuring pipe section, taking the grid nodes as measuring points, fixedly arranging a miniature water pressure sensor at each grid node of the three-dimensional net rack, and enabling the miniature water pressure sensor to pass throughThe pressure value F at each measuring point is obtained by the detection of the devicei。
7. The data iteration-based flow metering method of claim 6, wherein when the three-dimensional net rack is arranged, the side provided with the miniature water pressure sensor is directed towards the coming path of the fluid.
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| US6009741A (en) * | 1990-12-05 | 2000-01-04 | The United States Of America As Represented By The Secretary Of The Navy | Method of predicting steady incompressible fluid flow |
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