Flow rate calculation device and flow rate calculation method

Abstract

To provide a flow rate calculation device and a flow rate calculation method capable of suppressing deviation of a measuring result from a real flow rate while stabilizing the measuring accuracy of a flow rate of a fluid flowing through piping.SOLUTION: The flow rate calculation device for acquiring a flow rate of a fluid flowing through piping extending around an axis comprises: a flow velocity acquisition unit that acquires a real measured value of the flow velocity of the fluid at a first measurement point set on a measurement surface orthogonal to the axis; a turbulence velocity distribution acquisition unit that acquires a turbulence velocity distribution calculated on the basis of the real measured value and a turbulence velocity distribution estimation expression; an average flow velocity acquisition unit that acquires an average flow velocity; and an average flow rate acquisition unit that acquires an average flow rate by multiplying the average flow velocity by a channel section area of the piping.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a flow rate calculation device and a flow rate calculation method. [Background technology]

[0002] Patent Document 1 discloses a thermal flow meter that measures the flow rate of a fluid flowing through a pipe (fluid pipe). When measuring the flow rate of a fluid, depending on the installation environment of the pipe, it may not be possible to ensure a sufficient straight pipe length upstream of the installation location of the flow meter. In such cases, it is known that the velocity distribution of the fluid in the pipe becomes non-uniform, reducing the measurement accuracy of the flow meter.

[0003] The flowmeter described in Patent Document 1 places multiple flow velocity detection elements at predetermined positions in the pipe and calculates the average flow rate from the outputs of these flow velocity detection elements. This stabilizes the measurement accuracy of the flowmeter even when the straight pipe length of the pipe cannot be secured sufficiently and the velocity distribution of the fluid in the pipe is uneven. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-59191 Summary of the Invention [Problem to be solved by the invention]

[0005] In the flowmeter described in Patent Document 1, the flow rate detection elements are arranged at the center of the pipe and at equal intervals in the circumferential direction, each at an equal distance from the center. Therefore, for example, if the velocity distribution of the fluid in the radial direction inside the pipe is extremely non-uniform, the actual flow rate of the fluid flowing inside the pipe may differ from the measurement result of the flowmeter, regardless of the measurement accuracy.

[0006] The present disclosure has been made in consideration of the above circumstances, and provides a flow rate calculation device and a flow rate calculation method that can stabilize the measurement accuracy of the flow rate of a fluid flowing through a pipe while preventing the measurement results from deviating from the actual flow rate. [Means for solving the problem]

[0007] A flow rate calculation device according to a first aspect of the present disclosure is a flow rate calculation device that acquires a flow rate of a fluid flowing through a pipe extending around an axis line, and is provided on a measurement surface perpendicular to the axis line. The piping a turbulent velocity distribution acquisition unit that acquires, for each of the actual measured values, a turbulent velocity distribution calculated based on each of the actual measured values ​​and a turbulent velocity distribution estimation equation; an average velocity distribution acquisition unit that acquires an average velocity distribution from the plurality of turbulent velocity distributions for each of the actual measured values; an average flow velocity acquisition unit that acquires an average flow velocity from the average velocity distribution; and an average flow rate acquisition unit that acquires an average flow rate by multiplying the average flow velocity by a flow path cross-sectional area of ​​the piping.

[0008] A flow rate calculation method according to a second aspect of the present disclosure is a flow rate calculation method for acquiring a flow rate of a fluid flowing through a pipe extending around an axis line, the method comprising: The piping acquiring actual measured values ​​of the flow velocity of the fluid at a plurality of first measurement points arranged in a row in the radial direction of the pipe and at a second measurement point arranged at an intersection of the axis and the measurement surface; acquiring a turbulent velocity distribution calculated for each of the actual measured values ​​based on each of the actual measured values ​​and a turbulent velocity distribution estimation equation; acquiring an average velocity distribution from the plurality of turbulent velocity distributions for each of the actual measured values; acquiring an average flow velocity from the average velocity distribution; and acquiring an average flow rate by multiplying the average flow velocity by a flow path cross-sectional area of ​​the pipe. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a flow rate calculation device and a flow rate calculation method that can stabilize the measurement accuracy of the flow rate of a fluid flowing inside a pipe while preventing the measurement result from deviating from the actual flow rate. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a piping and a flow meter according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] 1 is a functional block diagram illustrating a configuration of a flow rate calculation device according to an embodiment of the present disclosure. [Figure 4] 4 is a flowchart illustrating an operation of a flow rate calculation device according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a hardware configuration diagram illustrating a configuration of a computer according to an embodiment of the present disclosure. [Figure 6] FIG. 1 is a perspective view of a pipe according to an embodiment of the present disclosure. [Figure 7] 10 shows measurement results of a flow rate calculation device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a piping and a flow meter according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] (Plumbing) As shown in FIG. 1 , the pipe 1 is a cylindrical pipe through which a fluid V flows. The pipe 1 extends along the direction of the axis O, with the axis O as its center. A virtual measurement plane X perpendicular to the axis O is formed at a midpoint in the extension direction of the pipe 1. In this embodiment, the measurement plane X is a virtual plane for defining the positions of a first measurement point P1 and a second measurement point P2, which are measurement points for the fluid V flowing inside the pipe 1.

[0013] As shown in Fig. 2, the first measurement points P1 are virtual points arranged at intervals from the axis O in the radial direction of the axis O on the measurement surface X. In this embodiment, six first measurement points P1 are arranged in a row in the vertical direction Dv. More specifically, three points are arranged symmetrically about the axis O at intervals.

[0014] The second measurement point P2 is a virtual point located at the intersection of the axis O and the measurement plane X. That is, the second measurement point P2 is located at the center inside the pipe 1.

[0015] (current meter) The flow meter 2 is a Pitot tube that measures the flow velocity of the fluid V flowing inside the pipe 1. The flow meter 2 is provided inside the pipe 1 so as to be movable in the vertical direction Dv. The flow meter 2 has a nose tube 3 , a main tube 4 , and a differential pressure measurement tube 5 .

[0016] The nasal tube 3 is a tube with a double-tube structure extending inside the piping 1 in the flow direction F of the fluid V. The nasal tube 3 has a total pressure nasal tube 3a and a static pressure nasal tube 3b. The static pressure nasal tube 3b is attached to the total pressure nasal tube 3a so as to cover the total pressure nasal tube 3a from the outside, and the tube wall of the static pressure nasal tube 3b and the tube wall of the total pressure nasal tube 3a are connected at one end on one side in the flow direction F. Therefore, inside the static pressure nasal tube 3b, the interior of the total pressure nasal tube 3a and the interior of the static pressure nasal tube 3b are separated by the tube wall of the total pressure nasal tube 3a, and each forms a different flow path inside.

[0017] A total pressure hole 2a is formed at one end of the total pressure nasal tube 3a, connecting the inside of the total pressure nasal tube 3a with the inside of the piping 1. The total pressure hole 2a opens to one side of the flow direction F of the fluid V on the measurement surface X. The fluid V flowing inside the piping 1 flows into the inside of the total pressure nasal tube 3a at full pressure through the total pressure hole 2a.

[0018] The static pressure nasal tube 3b has static pressure holes 2b formed on its side surface, which connect the inside of the static pressure nasal tube 3b with the inside of the piping 1. A plurality of static pressure holes 2b are formed at equal intervals along the side surface of the static pressure nasal tube 3b. In this embodiment, four static pressure holes 2b are formed at equal intervals along the side surface of the static pressure nasal tube 3b.

[0019] Each static pressure hole 2b opens in a direction approximately perpendicular to the flow direction F of the fluid V. Of the fluid V flowing in the flow direction F near the flow meter 2 inside the pipe 1, the fluid V that separates without flowing into the total pressure hole 2a decreases in flow velocity, its pressure increases, and it becomes statically pressurized. The fluid V that has become statically pressurized flows into the static pressure nasal tube 3b through the static pressure hole 2b.

[0020] The main pipe 4 is a pipe having a double pipe structure that guides the fluid V that has flowed into the inside of the nasal pipe 3 to the outside of the piping 1. The main pipe 4 extends in the vertical direction Dv from the outside to the inside of the piping 1 so as to penetrate the pipe wall of the piping 1. The main pipe 4 has a total pressure main pipe 4a and a static pressure main pipe 4b.

[0021] The static pressure main pipe 4b is attached to the total pressure main pipe 4a so as to cover the total pressure main pipe 4a from the outside. The upper end of the total pressure main pipe 4a is connected to the other end of the total pressure nasal tube 3a so as to communicate with the inside of the total pressure nasal tube 3a. The upper end of the static pressure main pipe 4b is connected to the other end of the static pressure nasal tube 3b so as to communicate with the inside of the static pressure nasal tube 3b. Therefore, the fluid V flowing inside the total pressure nasal tube 3a flows into the total pressure main pipe 4a, and the fluid V flowing inside the static pressure nasal tube 3b flows into the static pressure main pipe 4b.

[0022] In this embodiment, a gap (not shown) between the outer circumferential surface of the static pressure main pipe 4b and the pipe wall of the piping 1 is sealed, for example, with a metal seal or the like. That is, the main pipe 4 is capable of moving in the up-and-down direction Dv with the gap between the outer circumferential surface of the static pressure main pipe 4b and the pipe wall of the piping 1 sealed. Note that the gap is not limited to being sealed with a metal seal, and may be sealed with a sealing material such as synthetic resin.

[0023] The differential pressure measurement pipe 5 is a pipe forming a curved piping structure that receives the fluid V inside the piping 1 guided by the main pipe 4 and measures the pressure of the fluid V. One end of the differential pressure measurement pipe 5 is connected to the lower end of the total pressure main pipe 4a so as to communicate with the interior of the total pressure main pipe 4a. The other end of the differential pressure measurement pipe 5 is connected to the lower end of the static pressure main pipe 4b so as to communicate with the interior of the static pressure main pipe 4b.

[0024] Therefore, the differential pressure measurement pipe 5 connects the total pressure main pipe 4a and static pressure main pipe 4b of the main pipe 4. The differential pressure measurement pipe 5 has a differential pressure measurement sensor unit 5a such as a manometer. The fluid V that flows from the total pressure hole 2a into the total pressure nasal tube 3a and the fluid V that flows from the static pressure hole 2b into the static pressure nasal tube 3b flow through different flow paths within the nasal tube 3 and the main pipe 4, respectively, and are led to the differential pressure measurement pipe 5.

[0025] The differential pressure measurement sensor unit 5a measures the differential pressure generated between the fluid V in a full pressure state and the fluid V in a static pressure state, which are guided from these flow paths to the differential pressure measurement pipe 5. The differential pressure measurement sensor unit 5a is not limited to a manometer, and may be a diaphragm or the like.

[0026] 1 and 2, the total pressure hole 2a opens to one side in the flow direction F of the fluid V at a first measurement point P1 that is below the axis O and closest to the axis O. In this embodiment, by moving the flow meter 2 in the vertical direction Dv, the total pressure hole 2a can be positioned at the first measurement point P1 and the second measurement point P2. In other words, by moving the flow meter 2 in the vertical direction Dv, the flow velocities of the fluid V at the first measurement point P1 and the second measurement point P2 can be measured.

[0027] (Flow rate calculation device) Next, a flow rate calculation device according to an embodiment of the present disclosure will be described. The flow rate calculation device 10 is a device that acquires the flow rate of a fluid V flowing through a pipe 1. As shown in FIG. 1, the flow rate calculation device 10 is provided outside the pipe 1. The flow rate calculation device receives a measurement value from a flow velocity meter 2 as an input. As shown in FIG. 3, the flow rate calculation device 10 includes a flow velocity acquisition unit 11, a turbulent flow velocity distribution acquisition unit 12, an average velocity distribution acquisition unit 13, an average flow velocity acquisition unit 14, and an average flow rate acquisition unit 15.

[0028] (Flow velocity acquisition part) The flow velocity acquiring unit 11 acquires actual measured values ​​of the flow velocity of the fluid V at the first measurement point P1 and the second measurement point P2. In this embodiment, the flow velocity acquiring unit 11 acquires the actual measured values ​​measured by the flow velocity meter 2. For example, one end of a sensor signal line (not shown) whose other end is connected to the differential pressure measuring sensor unit 5a of the flow velocity meter 2 is connected to the flow velocity acquiring unit 11. This allows the flow velocity acquiring unit 11 to acquire the measurement value output by the pressure sensor of the flow velocity meter 2 as the actual measured value via the sensor signal line.

[0029] (Turbulent velocity distribution acquisition part) The turbulent flow velocity distribution acquisition unit 12 acquires a turbulent flow velocity distribution for each actual measurement value based on the actual measurement value and the turbulent flow velocity distribution estimation equation. In this embodiment, the turbulent flow velocity distribution acquisition unit 12 acquires the turbulent flow velocity distribution based on the actual measurement values ​​at the first measurement point P1 and the second measurement point P2 acquired by the flow velocity acquisition unit 11 and a "power law" as a turbulent flow velocity distribution estimation equation. The turbulent flow velocity distribution acquisition unit estimates the velocity distribution of the turbulent flow in the circular pipe in the radial direction of the axis inside the piping 1 based on the actual measurement value and the turbulent flow velocity distribution estimation equation.

[0030] Here, we will outline the "power law" for estimating turbulent velocity distribution. To estimate the turbulent velocity distribution, the following equation (1) is used, which is described in Chapter 8, pp. 69-93, of "Mechanical Engineering Handbook, Basics, Alpha 4, Fluid Engineering," edited by the Japan Society of Mechanical Engineers, First Edition, Japan, Japan Society of Mechanical Engineers, January 20, 2006. u / U=(y / a)^(1 / n)=(1-r / a)^(1 / n) …(1)

[0031] Here, y is the distance (known) from the wall of pipe 1 to the first measurement point P1. a is the radius of pipe 1 (known). y can be expressed as ar, where r is the distance (known) from the intersection of axis O and measurement plane X to the first measurement point P1. u is the velocity of fluid V in flow direction F at distance y from the wall of pipe 1. U is the velocity in flow direction F at the intersection of axis O and measurement plane X (second measurement point P2).

[0032] n is a constant that can be uniquely determined by the Reynolds number (Re). The value of n is determined, for example, by the following equation (2), which is derived from the results of general experiments. n=3.45×Re^0.07 …(2) For the Reynolds number (Re), any value within the range of 4×10^3 to 3.24×10^6 is preferably adopted.

[0033] Therefore, the turbulent velocity distribution can be estimated for each actual measurement value based on the actual measurement values ​​at the first measurement point P1 and the second measurement point P2 acquired by the flow velocity acquisition unit 11 and the theoretical value calculated from known values ​​using the above formula (1). Specifically, the turbulent velocity distribution for each actual measurement value can be calculated by applying the above formula (1) to each actual measurement value acquired by the flow velocity acquisition unit 11 and performing fitting such as extrapolation.

[0034] (Average speed distribution acquisition part) The average velocity distribution acquisition unit 13 acquires an average velocity distribution from the multiple turbulent velocity distributions acquired for each actual measurement value. In this embodiment, the average velocity distribution acquisition unit 13 acquires one average velocity distribution by averaging the multiple turbulent velocity distributions acquired by the turbulent velocity distribution acquisition unit 12.

[0035] (Average flow velocity acquisition part) The average flow velocity acquiring unit 14 acquires the average flow velocity from the average velocity distribution. In this embodiment, the average flow velocity acquiring unit 14 acquires the average flow velocity, which is a single value, by averaging the flow velocities of the average velocity distribution acquired by the average velocity distribution acquiring unit 13.

[0036] (Average flow rate acquisition part) The average flow rate acquiring unit 15 acquires the average flow rate by multiplying the average flow velocity by the flow path cross-sectional area of ​​the pipe 1. In this embodiment, the average flow rate acquiring unit 15 derives the average flow rate from the average flow velocity acquired by the average flow velocity acquiring unit 14. Specifically, the average flow rate acquiring unit 15 derives the average flow rate (Q) using the following equation (3). Q = V × A … (3) Here, V is the average flow velocity acquired by the average flow velocity acquisition unit 14. A is the flow path cross-sectional area of ​​the pipe 1 (known).

[0037] (Operation of flow rate calculation device) Next, the operation of the flow rate calculation device 10 will be described with reference to FIG.

[0038] The flow velocity acquiring unit 11 acquires the actual measured value of the flow velocity of the fluid V at the first measurement point P1 (step S1). Next, the flow velocity acquiring unit 11 acquires the actual measured value of the flow velocity of the fluid V at the second measurement point P2 (step S2). The turbulent flow velocity distribution acquisition unit 12 acquires, for each actual measurement value, a turbulent flow velocity distribution calculated based on the actual measurement value acquired by the flow velocity acquisition unit 11 and the turbulent flow velocity distribution estimation equation (step S3).

[0039] The average velocity distribution acquisition unit 13 acquires an average velocity distribution from the plurality of turbulent velocity distributions acquired for each actual measurement value by the turbulent velocity distribution acquisition unit 12 (step S4). The average flow velocity acquiring unit 14 acquires the average flow velocity from the average velocity distribution acquired by the average velocity distribution acquiring unit 13 (step S5). The average flow rate acquiring unit 15 acquires the average flow rate by multiplying the average flow velocity acquired by the average flow velocity acquiring unit 14 by the cross-sectional area of ​​the flow path of the pipe 1 (step S6).

[0040] (Action and effect) In the flow rate calculation device 10 of the above embodiment, an average flow rate is obtained as a measurement result through a process of obtaining an average velocity distribution from a turbulent velocity distribution calculated based on the actual measurement value of the flow velocity at the first measurement point and the turbulent velocity distribution estimation equation. This makes it possible to obtain an average velocity distribution that more closely matches the true turbulent velocity distribution in the pipe 1, compared to a configuration that does not go through the process of averaging the turbulent velocity distribution after acquisition. In other words, it is possible to ultimately obtain an average flow rate that is close to the actual flow rate. Therefore, even in an environment where it is difficult to ensure a sufficient straight pipe length upstream, it is possible to stabilize the measurement accuracy of the flow rate of the fluid V flowing in the pipe 1 and prevent the measurement result from deviating from the actual flow rate.

[0041] Furthermore, in the flow rate calculation device 10 of the above embodiment, the first measurement points P1 are arranged in a row on the measurement surface X in the radial direction of the axis O, so the distribution of actual measurement values ​​acquired by the flow velocity acquisition unit 11 at each first measurement point P1 can be made closer to the distribution of actual velocities. Therefore, for example, even if the velocity distribution of the fluid V in the radial direction of the axis O is extremely non-uniform, the average flow rate of the fluid V finally acquired by the average flow rate acquisition unit 15 can be made closer to the actual flow rate.

[0042] The inventors also experimentally obtained flow rates measured by the flow calculation device 10 when the flow velocity of the fluid V was obtained only at the first measurement point P1, and flow rates measured by the flow calculation device 10 when the flow velocity was obtained at the first measurement point P1 and the second measurement point P2. A predetermined flow rate of the fluid V sent into the pipe 1 was then set as a reference flow rate, and the measurement results of the above two patterns of flow rates were compared with the reference flow rate. As a result, it was confirmed that the deviation from the reference flow rate was smaller when the flow velocity was obtained at the first measurement point P1 and the second measurement point P2 than when the flow velocity of the fluid V was obtained only at the first measurement point P1.

[0043] In the flow rate calculation device 10 of the above embodiment, an actual measurement value of the flow velocity of the fluid V is also obtained at the second measurement point P2, which is the center of the flow path in the pipe 1. This allows the average flow rate of the fluid V finally obtained by the average flow rate obtaining unit 15 to be closer to the actual flow rate.

[0044] Furthermore, according to the flow rate calculation method of the above embodiment, even in an environment where it is difficult to secure a sufficient upstream straight pipe length, it is possible to stabilize the measurement accuracy of the flow rate of the fluid V flowing within the piping 1 while preventing the measurement results from deviating from the actual flow rate.

[0045] Furthermore, according to the flow rate calculation method of the above embodiment, the finally obtained average flow rate of the fluid V can be made closer to the actual flow rate.

[0046] [Other embodiments] Although the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configurations are not limited to those of the embodiments, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope of the gist of the present disclosure. Furthermore, the present disclosure is not limited to the embodiments, but is limited only by the claims.

[0047] FIG. 5 is a hardware configuration diagram showing the configuration of the computer 1100 according to this embodiment. The computer 1100 includes a processor 1110 , a main memory 1120 , storage 1130 , and an interface 1140 .

[0048] The flow rate calculation device 10 described above is implemented in a computer 1100. The operations of the above-described processing units are stored in the form of a program in a storage 1130. The processor 1110 reads the program from the storage 1130, loads it into the main memory 1120, and executes the above-described processing in accordance with the program. The processor 1110 also allocates storage areas in the main memory 1120 corresponding to the above-described storage units in accordance with the program.

[0049] The program may be for realizing some of the functions to be performed by the computer 1100. For example, the program may be combined with other programs already stored in the storage 1130 or other programs implemented in other devices to perform the functions. Furthermore, the computer 1100 may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions to be performed by the processor 1110 may be realized by the integrated circuit.

[0050] Examples of storage 1130 include a magnetic disk, a magneto-optical disk, and a semiconductor memory. Storage 1130 may be an internal medium directly connected to the bus of computer 1100, or an external medium connected to computer 1100 via interface 1140 or a communication line. Furthermore, when this program is distributed to computer 1100 via a communication line, computer 1100 that receives the program may load the program into main memory 1120 and execute the above-mentioned processing. Storage 1130 is a non-transitory tangible storage medium.

[0051] The program may also be for realizing part of the above-mentioned functions. Furthermore, the program may be a so-called differential file (differential program) that realizes the above-mentioned functions in combination with another program already stored in the storage 1130.

[0052] In the above embodiment, the flow meter 2 is moved in the vertical direction Dv to receive the fluid V from the total pressure hole 2a and the static pressure hole 2b at the first measurement point P1 and the second measurement point P2, but a configuration in which one flow meter 2 is provided for each of the first measurement point P1 and the second measurement point P2 is also possible. This allows the flow velocity acquisition unit 11 to acquire actual measured values ​​of the flow velocity of the fluid V at the same time. This further reduces the discrepancy between the actual flow rate of the fluid flowing through the piping and the measurement results.

[0053] In the above embodiment, the first measurement points P1 are arranged symmetrically about the axis O in the vertical direction Dv, with three points spaced apart from each other, for a total of six points arranged in a row in the vertical direction Dv. However, this configuration is not limited to this. Any configuration may be used as long as two or more first measurement points P1 are arranged at any positions on the measurement surface X. This also makes it possible to obtain a turbulent velocity distribution at each first measurement point P1 and average multiple turbulent velocity distributions, thereby obtaining an average velocity distribution that closely matches the true turbulent velocity distribution in the pipe 1.

[0054] Furthermore, a single first measurement point P1 may be located at any position on the measurement plane X. In this case, the flow velocity acquisition unit 11 acquires an actual measurement value of the flow velocity at the first measurement point P1, and the turbulent flow velocity distribution acquisition unit 12 acquires a turbulent flow velocity distribution calculated based on this actual measurement value and the turbulent flow velocity distribution estimation equation. Next, the average flow velocity acquisition unit 14 acquires the average flow velocity from this turbulent flow velocity distribution. This also makes it possible to obtain the turbulent velocity distribution at the first measurement point P1, and then obtain the average flow velocity from this turbulent velocity distribution. Therefore, it is possible to ultimately obtain an average flow rate that is close to the actual flow rate from this average flow velocity.

[0055] In the above embodiment, the flow meter 2 is a Pitot tube that measures the flow velocity of the fluid V flowing inside the pipe 1, but is not limited to a Pitot tube. The flow meter 2 may be any measuring instrument that can measure the flow velocity. Examples of measuring instruments that can measure the flow velocity include a hot wire flow meter and an electromagnetic flow meter.

[0056] Furthermore, when measuring the flow velocity of the fluid in the pipe 1, a flow velocity meter having the same number of nasal tubes 3 as the first measurement points P1 may be used instead of the flow velocity meter 2 of the above embodiment. This also allows the flow velocity acquisition unit 11 to acquire actual measured values ​​of the flow velocity of the fluid V at the same time.

[0057] Furthermore, the above-mentioned power (exponential) law equation (1) is one example of a turbulent velocity distribution estimation equation, and other turbulent velocity distribution estimation equations may be used. For example, Eq. (13) described in Chemical Engineering, Vol. 31, edited by the Society of Chemical Engineers, Japan, No. 8, pp. 778-783, 1967, No. 8, pp. 778-783, may be used as other turbulent velocity distribution estimation equations. Various other known turbulent velocity distribution estimation equations may also be used to determine the turbulent velocity distribution. [Example]

[0058] Next, an embodiment of the flow rate calculation device will be described with reference to FIGS. In this embodiment, the configuration of the piping is partially different from that of the above embodiment, but the flow rate meter and the flow rate calculation device in this embodiment have the same configuration as in the above embodiment.

[0059] (Plumbing) As shown in Figure 6, the piping 1 of this embodiment has a straight pipe 1c centered on an axis O and extending along the axis O, and also has a first elbow pipe 1a and a second elbow pipe 1b that bend in a direction perpendicular to the axis O on one side (upstream side) of the axis O, and an upstream pipe 1d that extends in the vertical direction Dv.

[0060] The first elbow pipe 1a is a curved pipe 1 that bends in a horizontal direction (in-plane direction), which is perpendicular to the up-down direction Dv. The second elbow pipe 1b is a curved pipe 1 that bends in the up-down direction Dv (out-of-plane direction). The upstream pipe 1d extends from the upstream end of the second elbow pipe 1b, and receives fluid V from a blower (not shown) or the like provided outside the pipe 1, and guides the fluid V to the first elbow pipe 1a.

[0061] Therefore, for example, in the case of a pipe 1 in which the straight pipe length from the measurement position where the flow velocity meter 2 is installed in the straight pipe 1c to the upstream side cannot be made long, the pipe 1 has the first elbow pipe 1a and the second elbow pipe 1b installed upstream in the flow path of the fluid V, so it can be said that this is an environment in which the measurement accuracy of the flow rate of the fluid V is likely to deteriorate.

[0062] The fluid V may become a swirling flow when passing through a curved pipe 1 that bends in a direction perpendicular to the axis O, such as the first elbow pipe 1a and the second elbow pipe 1b. When the fluid V flowing inside the pipe 1 becomes a swirling flow, the velocity distribution becomes non-uniform.

[0063] (Measuring the flow velocity of a fluid) In this example, the center position inside the second elbow pipe 1b was set as the origin, and the straight pipe length was measured from the origin to the midpoint of the straight pipe 1c. In this example, the length of the straight pipe length was changed in four stages ((a), (b), (d), and (e) shown in FIG. 6), and the flow velocity of the fluid V at each stage was acquired by the flow velocity meter 2. The flow velocity of the fluid V acquired by the flow velocity meter 2 was input to the flow rate calculation device 10, which acquired the flow rate of the fluid V flowing through the piping 1.

[0064] In this example, six points from among the measurement points of the Pitot tube specified in 6.2 (Testing equipment and measuring methods) of JIS B 8330:2000 (Testing and inspection methods for fans), as in the above embodiment, were adopted as the first measurement points P1. Note that in this example, the flow meter 2 acquired only the flow velocity of the fluid V at the first measurement points P1.

[0065] Furthermore, the flow rate of the fluid V flowing through the pipe 1 was measured at positions (a), (b), (c), and (e) using the method specified in JIS B 8330:2000 (Testing and Inspection Methods for Fans). The results of this measurement were used as a comparative example and compared with the measurement results of the above example.

[0066] The measurement results are shown in a graph in Figure 7. The vertical axis shows the value (ratio to the reference flow rate) obtained by dividing the flow rate acquired by the flow rate calculation device 10 by a reference flow rate, which is a predetermined flow rate of the fluid V sent into the pipe 1. The horizontal axis shows the value obtained by dividing the straight pipe length (L) changed in the four stages described above by the diameter (D) of the pipe 1.

[0067] The examples are results obtained when the flow rate calculation device 10 according to the above embodiment is used. The comparative example shows the results when the method specified in JIS B 8330:2000 (Test and inspection method for fans) was used.

[0068] It can be seen that in all of the examples, the flow rates are within the range of 100±5% of the reference flow rate. In contrast, it can be seen that in the comparative example, when the straight pipe length (L) is short, the flow rate does not fall within the range of 100±5% of the reference flow rate.

[0069] These comparisons demonstrate that by using the flow calculation device 10 shown in the above embodiment, it is possible to stabilize the measurement accuracy of the flow rate of the fluid flowing through the pipe 1 while preventing the measurement results from deviating from the actual flow rate.

[0070] [Note] The flow rate calculation device and the flow rate calculation method described in the embodiment can be understood, for example, as follows.

[0071] [1] The flow rate calculation device 10 according to the first aspect is a flow rate calculation device 10 that acquires the flow rate of a fluid V flowing through a pipe 1 extending around an axis O, and includes: a flow rate acquisition unit 11 that acquires an actual measurement value of the flow rate of the fluid V at a first measurement point P1 located on a measurement plane X perpendicular to the axis O; a turbulent flow rate distribution acquisition unit 12 that acquires a turbulent flow rate distribution calculated based on the actual measurement value and a turbulent flow rate distribution estimation equation; an average flow rate acquisition unit 14 that acquires an average flow rate from the turbulent flow rate distribution; and an average flow rate acquisition unit 15 that acquires the average flow rate by multiplying the average flow rate by the flow path cross-sectional area of ​​the pipe 1.

[0072] According to the above configuration, the turbulent velocity distribution can be obtained at the first measurement point P1, and the average flow velocity can be obtained from this turbulent velocity distribution. Therefore, an average flow rate close to the actual flow rate can be finally obtained from this average flow velocity.

[0073] [2] The flow rate calculation device 10 according to the second aspect is the flow rate calculation device 10 of [1], wherein the flow rate acquisition unit 11 acquires the actual measured value of the flow rate at each of the plurality of first measurement points P1 arranged in a row in the radial direction of the axis O, the turbulent flow velocity distribution acquisition unit 12 acquires the turbulent flow velocity distribution for each of the actual measured values, and further includes an average velocity distribution acquisition unit 13 that acquires an average velocity distribution from the plurality of turbulent flow velocity distributions for each of the actual measured values, and the average flow rate acquisition unit 14 may acquire the average flow rate from the average velocity distribution instead of the turbulent flow velocity distribution.

[0074] With the above configuration, the first measurement points P1 are arranged in a row on the measurement plane X in the radial direction of the axis O, so the distribution of the actual measurement values ​​acquired by the flow velocity acquisition unit 11 at each first measurement point P1 can be made closer to the distribution of the actual velocity. Furthermore, compared to a configuration that does not undergo a process of averaging the turbulent velocity distribution after acquisition, an average velocity distribution that is more closely matched to the true turbulent velocity distribution in the pipe 1 can be obtained. In other words, an average flow rate close to the actual flow rate can be ultimately acquired.

[0075] [3] The flow rate calculation device 10 according to the third aspect is the flow rate calculation device 10 of [2], wherein the flow rate acquisition unit 11 may further acquire the actual measured value of the flow rate of the fluid V at a second measurement point P2 located at the intersection of the axis O and the measurement surface X.

[0076] According to the above configuration, an actual measurement value of the flow velocity of the fluid V is also obtained at the second measurement point P2, which is the center of the flow path in the pipe 1. This allows the average flow rate of the fluid V finally obtained by the average flow rate obtaining unit 15 to be closer to the actual flow rate.

[0077] [4] A flow rate calculation method according to a fourth aspect is a flow rate calculation method for acquiring the flow rate of a fluid V flowing through a pipe 1 extending around an axis O, and includes the steps of: acquiring an actual measurement value of the flow velocity of the fluid V at a first measurement point P1 located on a measurement plane X perpendicular to the axis O; acquiring a turbulent velocity distribution calculated based on the actual measurement value and a turbulent velocity distribution estimation formula; acquiring an average flow velocity from the turbulent velocity distribution; and acquiring an average flow rate by multiplying the average flow velocity by the flow path cross-sectional area of ​​the pipe 1.

[0078] According to the above method, the turbulent velocity distribution can be obtained at the first measurement point P1, and the average flow velocity can be obtained from this turbulent velocity distribution. Therefore, an average flow rate close to the actual flow rate can be finally obtained from this average flow velocity.

[0079] [5] A flow rate calculation method according to a fifth aspect is the flow rate calculation method of [4], wherein the step of acquiring the actual measured values ​​further includes acquiring actual measured values ​​of the flow velocity at each of a plurality of first measurement points P1 arranged in a row radially of the axis O, and the step of acquiring the turbulent velocity distribution further includes acquiring the turbulent velocity distribution for each of the actual measured values ​​and acquiring an average velocity distribution from the plurality of turbulent velocity distributions for each of the actual measured values, and the step of acquiring the average flow velocity further includes acquiring the average flow velocity from the average velocity distribution instead of the turbulent velocity distribution.

[0080] With the above method, the first measurement points P1 are arranged in a row on the measurement plane X in the radial direction of the axis O, so the distribution of the actual measurement values ​​acquired by the flow velocity acquisition unit 11 at each first measurement point P1 can be made closer to the distribution of the actual velocity. Furthermore, compared to a configuration that does not undergo the process of averaging the turbulent velocity distribution after acquisition, an average velocity distribution that is more closely matched to the true turbulent velocity distribution in the pipe 1 can be obtained. In other words, an average flow rate close to the actual flow rate can be ultimately acquired.

[0081] [6] The flow rate calculation method according to the sixth aspect is the flow rate calculation method of [5], further including a step of acquiring the actual measured value of the flow velocity of the fluid V at a second measurement point P2 located at the intersection of the axis O and the measurement surface X.

[0082] According to the above method, the finally obtained average flow rate of the fluid V can be made closer to the actual flow rate. [Explanation of symbols]

[0083] 1...Piping 1a...First elbow pipe 1b...Second elbow pipe 1c...Straight pipe 1d...Upstream pipe 2...Flow meter 2a...Total pressure hole 2b...Static pressure hole 3...Nose tube 3a...Total pressure nose tube 3b...Static pressure nose tube 4...Main pipe 4a...Total pressure main pipe 4b...Static pressure main pipe 5...Differential pressure measurement pipe 5a...Differential pressure measurement sensor section 10...Flow rate calculation device 11...Flow rate acquisition section 12...Turbulent flow velocity distribution acquisition section 13...Average velocity distribution acquisition section 14...Average flow rate acquisition section 15...Average flow rate acquisition section 1100...Computer 1110...Processor 1120...Main memory 1130...Storage 1140...Interface Dv...Up / down direction F...Flow direction O...Axis P1...First measurement point P2...Second measurement point V...Fluid X...Measurement surface

Claims

1. A flow rate calculation device that acquires a flow rate of a fluid flowing through a pipe extending around an axis line, a flow velocity acquiring unit that acquires actual measured values ​​of the flow velocity of the fluid at a plurality of first measurement points arranged in a row in the radial direction of the pipe on a measurement surface perpendicular to the axis, and at second measurement points arranged at intersections of the axis and the measurement surface; a turbulent velocity distribution acquisition unit that acquires, for each of the actual measurement values, a turbulent velocity distribution calculated based on each of the actual measurement values ​​and a turbulent velocity distribution estimation formula; an average velocity distribution acquisition unit that acquires an average velocity distribution from the plurality of turbulent velocity distributions for each of the actual measurement values; an average flow velocity acquisition unit that acquires an average flow velocity from the average velocity distribution; an average flow rate acquisition unit that acquires an average flow rate by multiplying the average flow velocity by a flow path cross-sectional area of ​​the pipe; A flow rate calculation device comprising:

2. A flow rate calculation method for acquiring a flow rate of a fluid flowing through a pipe extending around an axis line, comprising: acquiring actual measured values ​​of the flow velocity of the fluid at a plurality of first measurement points arranged in a row in the radial direction of the pipe on a measurement plane perpendicular to the axis, and at second measurement points arranged at intersections of the axis and the measurement plane; acquiring a turbulent velocity distribution calculated based on each of the actual measurement values ​​and a turbulent velocity distribution estimation equation for each of the actual measurement values; obtaining an average velocity distribution from the plurality of turbulent velocity distributions for each of the actual measurement values; obtaining a mean flow velocity from the mean velocity distribution; multiplying the average flow velocity by a cross-sectional area of ​​the pipe to obtain an average flow rate; A flow rate calculation method including:

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