Measurement and iterative calculation estimation method of fluid velocity with vortex flowmeter and non-temporary storage medium

Abstract

To provide a measurement and iterative calculation estimation method of fluid velocity with a vortex flowmeter in which the vortex flowmeter can adjust a Strouhal number during uncertain processes, to obtain the accurate fluid velocity to be measured.SOLUTION: A measurement and iterative calculation estimation method of fluid velocity with a vortex flowmeter includes: measuring a differential pressure fluctuation frequency of fluid vortices; obtaining a Nth Strouhal number; obtaining Nth estimated flow velocity based on the Nth Strouhal number and the differential pressure fluctuation frequency of vortices; obtaining a Nth Reynolds number of the fluid based on the Nth estimated flow velocity; obtaining a Reynolds number-Strouhal number correspondence table; obtaining a (N+1)th Strouhal number based on the Reynolds number-Strouhal number correspondence table and the Nth Reynolds number; and obtaining (N+1)th estimated flow velocity based on the (N+1)th Strouhal number and the differential pressure fluctuation frequency of vortices, where N is a positive integer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for measuring and iteratively estimating fluid flow velocity and a non-transitory storage medium applied to a vortex flowmeter. [Background technology]

[0002] A vortex flowmeter is a device that measures fluid flow velocity, utilizing the Karman vortex phenomenon of the fluid. The fluid may be a liquid or a gas. Vortex flowmeters are used in many industries, including the chemical, petroleum, and water conservancy industries. When using a vortex flowmeter, the vortex flowmeter is first installed in a pipe. When a fluid passes through the vortex flowmeter, vortices are generated, and the fluid flow velocity is calculated by measuring the frequency change in the differential pressure when vortices are generated.

[0003] Generally, in the measurement method using a vortex flowmeter, the Strouhal number of the fluid inside the vortex flowmeter is assumed to be a constant, so after measuring the frequency of the vortices, the fluid flow velocity can be calculated by using this constant.

[0004] However, at low or high fluid flow rates, or when the fluid is integrally mixed with air and the viscosity or density changes with temperature and temperature changes in the fluid production process, the assumption that the Strouhal number is a constant becomes invalid, and the error between the estimated flow rate and the fluid flow rate becomes excessively large.

[0005] In view of this, one of the most pressing issues at present is how to adjust the Strouhal number depending on the situation, so that the vortex flowmeter can accurately calculate the fluid flow velocity in the above-mentioned uncertain processes, such as low flow velocity, high flow velocity, temperature change, density change, and viscosity change. Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a method for measuring and iteratively estimating fluid flow velocity using a vortex flowmeter, which allows the vortex flowmeter to adjust the Strouhal number for the above-mentioned uncertain processes, such as low and high flow velocities, temperature changes, density changes, and viscosity changes, and the measured fluid flow velocity is more accurate than known measurement methods. [Means for solving the problem]

[0007] The present disclosure provides a method for measuring fluid flow velocity with a vortex flowmeter and iteratively estimating the flow velocity, the method including measuring a differential pressure fluctuation frequency of a vortex of a first fluid, obtaining an Nth Strouhal number, obtaining an Nth estimated flow velocity based on the Nth Strouhal number and the differential pressure fluctuation frequency of the vortex, obtaining the Nth Reynolds number of the first fluid based on the Nth estimated flow velocity, obtaining a Reynolds number-Strouhal number correspondence table, obtaining an N+1th Strouhal number based on the Reynolds number-Strouhal number correspondence table and the Nth Reynolds number, and obtaining the N+1th estimated flow velocity based on the N+1th Strouhal number and the differential pressure fluctuation frequency of the vortex, where N is a positive integer.

[0008] In some embodiments, obtaining the Nth Reynolds number of the first fluid based on the Nth estimated flow velocity further includes obtaining a kinematic viscosity and a density of the first fluid based on a temperature and a pressure of the first fluid, and obtaining the Nth Reynolds number of the first fluid based on the kinematic viscosity, the density, and the Nth estimated flow velocity.

[0009] In some embodiments, the measurement and iterative estimation method further includes calculating an error value based on the N+1 guessed flow rate and the N guessed flow rate.

[0010] In some embodiments, the measurement and iterative estimation method further includes comparing the error value to a threshold value.

[0011] In some embodiments, the measurement and iterative estimation method further includes outputting the N+1 th guessed flow speed as the resultant flow speed if the error value is less than or equal to a threshold value.

[0012] In some embodiments, the measurement and iterative estimation method further includes obtaining an N+1 Reynolds number of the first fluid based on the N+1 estimated flow velocity; searching for an N+2 Strouhal number corresponding to the N+1 Reynolds number from a Reynolds number-Strouhal number correspondence table; and obtaining the N+2 estimated flow velocity based on the N+2 Strouhal number and the differential pressure fluctuation frequency of the vortex.

[0013] In some embodiments, obtaining the Reynolds number-Strouhal number correspondence table further includes obtaining a reference Strouhal number and a reference Reynolds number using a second fluid, the second fluid having a predetermined flow velocity, and obtaining the Reynolds number-Strouhal number correspondence table by adjusting the predetermined flow velocity of the second fluid.

[0014] The present disclosure further provides a method for measuring and iteratively estimating a fluid flow velocity using a vortex flowmeter, including measuring a differential pressure fluctuation frequency of a vortex of the fluid, obtaining a Strouhal number, obtaining an estimated flow velocity based on the Strouhal number and the differential pressure fluctuation frequency of the vortex, obtaining a Reynolds number of the fluid based on the estimated flow velocity, and outputting the estimated flow velocity as a resultant flow velocity if the Reynolds number falls within a specific range.

[0015] In some embodiments, the particular range of fluids is a Reynolds number of about 20,000 or more and about 7,000,000 or less.

[0016] The present disclosure further provides a non-transitory storage medium having executable program code recorded thereon, which, when executed by a vortex flowmeter, performs the measurement and iterative estimation method described above. [Effects of the Invention]

[0017] As described above, known vortex flowmeter measurement methods assume the Strouhal number of the fluid to be a constant. This results in excessively large errors between the estimated flow rate and the fluid flow rate at low or high fluid flow rates, or when the fluid contains air and the viscosity or density changes due to temperature changes in the fluid production process. In contrast, the fluid flow rate measurement and iterative estimation method and non-transitory storage medium disclosed herein automatically calculate the estimated flow rate and then further calculate the Reynolds number, thereby identifying whether the interval containing the Reynolds number conforms to the assumption that the Strouhal number is a constant. This prevents the output of an estimated flow rate with an excessively large error as the resultant flow rate. If the interval containing the Reynolds number does not conform to the assumption that the Strouhal number is a constant, the Strouhal number can be adjusted using an iterative calculation method using the estimated fluid flow rate, thereby converging the estimated flow rate to the fluid flow rate. This allows the vortex flowmeter to accurately calculate the fluid flow rate at low or high fluid flow rates. By using the fluid flow velocity measurement and iterative calculation estimation method using a vortex flowmeter and the non-transitory storage medium disclosed herein, a user can automatically obtain a more accurate fluid flow velocity.

[0018] The following drawings and description set forth in detail one or more embodiments of the subject matter described herein, and other features, aspects, and advantages of the subject matter described herein will be apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a vortex flowmeter according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating the principle of the vortex flowmeter according to the present disclosure. [Figure 3] FIG. 3 is a schematic diagram of the correspondence relationship between the Reynolds number and the Strouhal number in the present disclosure. [Figure 4] FIG. 4 is a flowchart of one embodiment of the measurement and iterative estimation method of the present disclosure. [Figure 5]FIG. 5 is a flowchart of another embodiment of the measurement and iterative estimation method of the present disclosure. [Figure 6] FIG. 6 is a flowchart of yet another embodiment of a measurement and iterative estimation method according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0020] Terms such as "first," "second," "third," "fourth," and "fifth" used in this text describe various members, components, regions, layers, and / or portions, but should not be constrained by these terms. These terms may be used only to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Furthermore, unless the context clearly indicates otherwise, the terms "first," "second," "third," "fourth," and "fifth" used in this text do not imply any hierarchy or order.

[0021] Fig. 1 is a schematic diagram of an embodiment of a vortex flowmeter 1 according to the present disclosure, and Fig. 2 is a schematic diagram illustrating the principle of the vortex flowmeter 1 according to the present disclosure. Please refer to Figs. 1 and 2. The vortex flowmeter 1 of this embodiment may include, for example, a pipe 101, a column 11, a mechanical sensor 102, a piezoelectric element 103, a temperature sensor 104, a pressure sensor, a meter body 10, and a display 105.

[0022] The shape of the pipe 101 may be, for example, a hollow cylinder. The fluid 13 can pass through the inside of the pipe 101 (for example, from the right side to the left side in FIG. 1).

[0023] The cylinder 11 has both ends connected to the inner wall of the pipe 101, and may be provided, for example, in the center of the pipe 101. This ensures that the flow rates on both sides of the cylinder 11 are equal when the fluid 13 passes through the cylinder 11. The shape of the cylinder 11 may be, for example, a solid or hollow triangular prism, rectangular parallelepiped, circular cylinder, or polygonal prism. The width of the cross section of the cylinder 11 is the cylinder width 111. After passing through the cylinder 11 of the vortex flowmeter 1, the fluid 13 generates a vortex 14 and a differential pressure.

[0024] The mechanical sensor 102 is provided on one side (for example, the left side in FIG. 1) of the columnar body 11 in the direction D. This allows the mechanical sensor 102 to detect the vortex 14 or the differential pressure of the fluid 13. The mechanical sensor 102 oscillates in association with the vortex 14 or the differential pressure of the fluid 13. The frequency of the oscillation is the same as the generation frequency of the vortex 14.

[0025] The piezoelectric element 103 is connected to the mechanical sensor 102. Typically, the piezoelectric element 103 is made of a piezoelectric material, and may be made of a piezoelectric ceramic such as lead zirconate titanate. In this embodiment, the piezoelectric element 103 generates an electric signal in response to the oscillation of the mechanical sensor 102. The frequency of the electric signal is the same as the oscillation frequency of the mechanical sensor 102.

[0026] The meter body 10 is electrically connected to the piezoelectric element 103. The calculation unit in the meter body 10 can perform calculations on the electrical signal. For example, after obtaining the frequency of the electrical signal through Fourier transform, the fluid flow velocity can be calculated from the frequency.

[0027] The display 105 is electrically connected to the meter body 10. The display 105 may be, for example, but not limited to, an LCD screen, an LED display, or an OLED display. In this embodiment, the display 105 is used to display the fluid flow rate calculated by the meter body 10. In some embodiments, the display 105 may also display the temperature, pressure, or Reynolds number of the fluid 13.

[0028] The temperature sensor 104 is disposed within the pipe 101 and electrically connected to the meter body 10. In some embodiments, the temperature sensor 104 can measure the temperature of the fluid 13. The temperature can be displayed on a display 105, or the temperature data can be transmitted to the meter body 10 for calculation, such as, but not limited to, calculating the Reynolds number.

[0029] The pressure sensor is disposed within the piping 101 and electrically connected to the meter body 10. In some embodiments, the pressure sensor is capable of measuring the pressure of the fluid 13. The pressure may be displayed on the display 105, or the pressure data may be transmitted to the meter body 10 for calculation, such as, but not limited to, calculating the Reynolds number.

[0030] As described above, when the fluid 13 passes through the column 11 of the vortex flowmeter 1 and generates a vortex 14 and a differential pressure, the vortex 14 or the differential pressure can be detected by the mechanical sensor 102 of the vortex flowmeter 1. The vibration of the mechanical sensor 102 is converted into an electric signal by a piezoelectric material, and the electric signal is calculated by a processing unit in the meter body 10 of the vortex flowmeter 1. As a calculation method, for example, the frequency of the electric signal is obtained by Fourier transform. The fluid flow velocity of the fluid 13 is then calculated from the frequency, and the fluid flow velocity is displayed on the display 105. In some embodiments, the temperature sensor 104 and the pressure sensor may further measure the temperature and pressure of the fluid 13 and display them on the display 105 or use them to calculate the Reynolds number.

[0031] Next, we will explain the principle by which the vortex flowmeter 1 calculates the fluid flow velocity. The vortex flowmeter 1 measures the fluid flow velocity using the Karman vortex effect. When the fluid 13 passes through the vortex flowmeter 1, the Karman vortex effect occurs. The fluid 13 generates alternating vortices 14 on both sides of the cylinder 11. These vortices 14 are generated at a fixed frequency. The generation frequency is determined by the fluid flow velocity and the cylinder width 111 of the cylinder 11, and can be described by Equation 1.

[0032]

number

[0033] f is the generation frequency of the vortex 14, S t is the Strouhal number, V is the fluid flow velocity of the fluid 13 near the cylinder 11, and d is the cylinder width 111.

[0034] When the Reynolds number of the fluid 13 is greater than or equal to about 20,000 and less than or equal to about 7,000,000, the Strouhal number may be considered a constant. The Reynolds number of the fluid 13 in the vortex flowmeter 1 before it passes through the cylinder 11 can be expressed by Equation 2.

[0035]

number

[0036] Re is the Reynolds number, ρ is the density of the fluid 13, μ is the dynamic viscosity of the fluid 13,

number

number

[0037] By rearranging the Reynolds number in equation 2,

number

number

number

[0038] The equation of continuity in fluid mechanics

number

[0039]

number

[0040] It should be noted that Equation 3 is calculated based on the cross-sectional area of ​​the pipe 101 and the cross-sectional area of ​​the columnar body 11, and therefore Equation 3 differs depending on the structure of the vortex flowmeter 1.

[0041] By substituting Equation 1 into Equation 3 and eliminating V, we can obtain Equation 4.

[0042]

number

[0043] It should be noted that in the same vortex flowmeter 1, the column width 111 and the pipe diameter 12 are fixed.

number

number

[0044] Figure 3 is a schematic diagram of the correspondence relationship between the Reynolds number and the Strouhal number in the present disclosure. Please refer to Figures 2 and 3. When the Reynolds number is less than about 20,000 or greater than about 7,000,000, the Strouhal number changes in accordance with the Reynolds number. In this case, since the Strouhal number becomes a variable, Equation 4 is not an analytical solution form of the fluid flow velocity, but an equation form of the fluid flow velocity, which is expressed as, for example, Equation 5.

[0045]

number

[0046]

number

[0047] FIG. 4 is a flowchart of an embodiment of a measurement and iterative estimation method according to the present disclosure. Please refer to FIG. 4. In step S01, the differential pressure fluctuation frequency of the vortex of the first fluid is measured. In step S02, the Nth Strouhal number is obtained. In step S03, the Nth estimated flow velocity is obtained based on the Nth Strouhal number and the differential pressure fluctuation frequency of the vortex. In step S04, the Nth Reynolds number of the first fluid is obtained based on the Nth estimated flow velocity. In step S05, a Reynolds number-Strouhal number correspondence table is obtained. In step S06, the N+1th Strouhal number is obtained based on the Reynolds number-Strouhal number correspondence table and the Nth Reynolds number. In step S07, the N+1th estimated flow velocity is obtained based on the N+1st Strouhal number and the differential pressure fluctuation frequency of the vortex, where N is a positive integer. As a result, the fluid flow velocity is obtained by solving Equation 5 numerically.

[0048] Please refer to Figures 2 and 4. In step S01, the differential pressure fluctuation frequency of the vortex of the first fluid is measured. In this embodiment, after the vortex flowmeter 1 is connected to a pipe, the first fluid passes through the column 11 of the vortex flowmeter 1, generating a vortex 14 and a differential pressure. The differential pressure can be detected by a mechanical sensor of the vortex flowmeter 1. The vortex 14 or the differential pressure can be detected by the mechanical sensor of the vortex flowmeter 1, and then a calculation is performed by a processing unit within the vortex flowmeter 1. As a calculation method, for example, the differential pressure fluctuation frequency of the vortex of the first fluid is obtained by calculating the frequency of an electrical signal using Fourier transform, but this is not limited thereto. The higher the differential pressure fluctuation frequency of the vortex of the first fluid, the faster the fluid flow velocity of the first fluid. The first fluid can be, for example, but is not limited to, water, air, and saturated steam.

[0049] In step S02, the Nth Strouhal number is obtained. In this embodiment, the value of the Strouhal number used in a known vortex flowmeter is used as the Nth Strouhal number, and this is the first step of the iterative calculation. However, this is not limiting, and other values ​​of the Strouhal number may be obtained and the iterative calculation may be performed in subsequent steps. In some embodiments, N is counted from 1.

[0050] In step S03, the Nth estimated flow velocity is obtained based on the Nth Strouhal number and the differential pressure fluctuation frequency of the vortex. In this embodiment, the Nth estimated flow velocity can be obtained by substituting the Nth Strouhal number and the differential pressure fluctuation frequency of the vortex into Equation 4, and is expressed, for example, as Equation 6.

[0051]

number

[0052]

number

number

[0053] In step S04, the Nth Reynolds number of the first fluid is obtained based on the Nth estimated flow velocity. Based on the Nth estimated flow velocity and other parameters of the first fluid, the Nth Reynolds number of the first fluid can be obtained by table reference or substitution into Equation 2. For example, it can be searched from Table 1 or Equation 7 can be used.

[0054] [Table 1]

[0055]

number

[0056] Re N is the Nth Reynolds number.

[0057] In step S05, a Reynolds number-Strouhal number correspondence table is obtained. In step S06, the (N+1)th Strouhal number is obtained based on the Reynolds number-Strouhal number correspondence table and the Nth Reynolds number. The Reynolds number-Strouhal number correspondence table can be obtained, for example, from experiments (described in detail below) or other databases, but the present invention is not limited thereto. Then, the (N+1)th Strouhal number corresponding to the Nth Reynolds number is searched for based on the table. For example, it is searched from Table 2.

[0058] [Table 2]

[0059] In step S07, the (N+1)th estimated flow velocity is obtained based on the (N+1)th Strouhal number and the differential pressure fluctuation frequency of the vortex. In this embodiment, the (N+1)th estimated flow velocity can be calculated by substituting the (N+1)th Strouhal number and the differential pressure fluctuation frequency of the vortex into Equation 5, and is expressed, for example, as Equation 8.

[0060]

number

[0061]

number

number

[0062] In some embodiments, in step S07, after obtaining the N+1th estimated flow velocity based on the N+1th Strouhal number and the differential pressure fluctuation frequency of the vortex, the N+1st Reynolds number of the first fluid may be obtained based on the N+1st estimated flow velocity. Then, the N+2nd Strouhal number corresponding to the N+1st Reynolds number is searched for in the Reynolds number-Strouhal number correspondence table, and the N+2nd estimated flow velocity is obtained based on the N+2nd Strouhal number and the differential pressure fluctuation frequency of the vortex.

[0063] When obtaining the N+1 Reynolds number of the first fluid based on the N+1 estimated flow velocity, in some embodiments, the N+1 Reynolds number of the first fluid can be obtained by table lookup or Equation 2. For example, by searching Table 1 or using Equation 9.

[0064]

number

[0065] Re N+1 is the N+1 Reynolds number.

[0066] The N+2 Strouhal number corresponding to the N+1 Reynolds number is retrieved from a Reynolds number-Strouhal number correspondence table. The Reynolds number-Strouhal number correspondence table can be obtained, for example, from experiments (described in detail below) or other databases, but the present invention is not limited thereto. Then, the N+2 Strouhal number corresponding to the N+1 Reynolds number is retrieved based on the table. For example, the table is retrieved from Table 2.

[0067] The N+2 estimated flow velocity is obtained based on the N+2 Strouhal number and the differential pressure fluctuation frequency of the vortex. In some embodiments, the N+2 estimated flow velocity can be obtained by substituting the N+2 Strouhal number and the differential pressure fluctuation frequency of the vortex into Equation 5, as shown in Equation 10, for example.

[0068]

number

[0069]

number

number

[0070] In some embodiments, the calculation can continue in a similar manner to obtain a fourth guess flow rate, a fifth guess flow rate, an Nth guess flow rate, and so on. These guess flow rates approach a specific value until the values ​​of the guess flow rates on both sides of the equals sign in Equation 5 are equal. This specific value is the solution to Equation 5, i.e., the fluid flow rate of the first fluid. In some embodiments, if these guess flow rates do not approach the specific value, the value of the Nth Strouhal number obtained in step S02 can be adjusted and the iterative calculation can be repeated to bring the guess flow rate closer to the specific value.

[0071] In some embodiments, when obtaining the Nth Reynolds number of the first fluid based on the Nth estimated flow velocity in step S04, the kinematic viscosity and density of the first fluid may be obtained based on the temperature and pressure of the first fluid, and the Nth Reynolds number of the first fluid may be obtained based on the kinematic viscosity, density, and Nth estimated flow velocity.

[0072] The kinematic viscosity and density of the first fluid are obtained based on the temperature and pressure of the first fluid. The kinematic viscosity and density of the first fluid may be calculated based on the temperature and pressure of the first fluid or may be searched for. For example, they may be calculated using a fluid dynamics model that is compatible with the first fluid or may be obtained from another database. In this way, the kinematic viscosity and density of the first fluid can be obtained.

[0073] The Nth Reynolds number of the first fluid is obtained based on the kinematic viscosity, density, and Nth estimated flow velocity. The Nth Reynolds number of the first fluid may be retrieved from Table 1, or may be obtained by performing a table lookup based on the Nth estimated flow velocity and other parameters of the first fluid, or by substituting the Nth Reynolds number into Equation 2, as shown in Equation 7, for example.

[0074] FIG. 5 is a flowchart of another embodiment of the measurement and iterative calculation estimation method according to the present disclosure. Please refer to FIG. 5. In step S08, it is determined whether the error value is equal to or less than a threshold value. In step S09, the (N+1)th estimated flow velocity is output as the resultant flow velocity. In step S10, N is replaced with N+1, and then steps S04 to S07 are executed.

[0075] See Figures 2, 4, and 5. In step S08, an evaluation method may be, for example, calculating an error value from the (N+1)th estimated flow velocity and the Nth estimated flow velocity. The error value may be calculated, for example, by |((N+1)th estimated flow velocity - (N)th estimated flow velocity) / (N+1)th estimated flow velocity|. The error value may be compared with a threshold value by, for example, |((N+1)th estimated flow velocity - (N)th estimated flow velocity) / (N+1)th estimated flow velocity|≦(threshold value). The threshold value may be set according to the accuracy requirement, and a small threshold value may be set when high accuracy is required.

[0076] In step S09, if the error value is equal to or less than the threshold value, the N+1-th estimated flow velocity is output as the resultant flow velocity. That is, the N+1-th estimated flow velocity is output as the result of measurement and calculation, for example, on the display panel of the vortex flowmeter 1.

[0077] In step S10, if the error value is greater than the threshold value, N is replaced with N+1, and steps S04 to S07 are then executed, and the calculation is continued until the error value becomes equal to or less than the threshold value.

[0078] In some embodiments, when the Reynolds number-Strouhal number correspondence table is obtained in step S05, a reference Strouhal number and a reference Reynolds number may be obtained using a second fluid. The second fluid has a predetermined flow velocity, and the Reynolds number-Strouhal number correspondence table is obtained by adjusting the predetermined flow velocity of the second fluid.

[0079] A reference Strouhal number and a reference Reynolds number are obtained using a second fluid, the second fluid having a predetermined flow velocity, which may be the same as or have similar properties to the first fluid.

[0080] The Reynolds number-Strouhal number correspondence table is obtained by adjusting the preset flow velocity of the second fluid. Adjusting the preset flow velocity of the second fluid means, in other words, using the preset flow velocity as a manipulated variable to calculate different Reynolds numbers from Equation 2 and obtain the corresponding Strouhal number from Equation 1, thereby obtaining the Reynolds number-Strouhal number correspondence table. It should be noted that in this step, since the preset flow velocity of the second fluid is the manipulated variable, the fluid flow velocity of the fluid 13 near the cylinder 11 in Equation 1 becomes a known quantity, and the Strouhal number becomes an unknown quantity. In this way, the Reynolds number-Strouhal number correspondence table can be created in advance through experiments, such as Table 2.

[0081] As described above, the measurement method using a known vortex flowmeter assumes the Strouhal number of the fluid 13 to be a constant. This results in an excessively large error between the estimated flow rate and the fluid flow velocity at low or high fluid flow rates, or when the fluid 13 is mixed with air and the viscosity or density changes due to temperature changes in the fluid production process. In contrast, the measurement and iterative estimation method disclosed herein uses the estimated flow rate of the fluid 13 to adjust the Strouhal number through iterative calculations, thereby converging the estimated flow rate to the fluid flow rate. This allows the vortex flowmeter 1 to accurately calculate the fluid flow rate at low or high fluid flow rates. By using the measurement and iterative estimation method disclosed herein, users can obtain a more accurate fluid flow rate.

[0082] FIG. 6 is a flowchart of yet another embodiment of the measurement and iterative estimation method of the present disclosure. Please refer to FIG. 6. In step S11, the differential pressure fluctuation frequency of a fluid vortex is measured. In step S12, the Strouhal number is obtained. In step S13, an estimated flow velocity is obtained based on the Strouhal number and the differential pressure fluctuation frequency of the vortex. In step S14, the Reynolds number of the fluid is obtained based on the estimated flow velocity. In step S15, if the Reynolds number falls within a specific range, the estimated flow velocity is output as the resultant flow velocity.

[0083] See FIGS. 2 and 6. Steps S11 to S14 are similar to steps S01 to S04, and therefore will not be described again in detail. It should be noted that in step S15, if the Reynolds number falls within a specific range, the estimated flow velocity is output as the resultant flow velocity. If the Reynolds number falls within a specific range, the error value between the estimated flow velocity calculated by assuming the Strouhal number of the fluid 13 in the vortex flowmeter 1 to be a constant and the fluid flow velocity also falls within a specific range. Therefore, a range of the allowable fluid flow velocity error may be set to select a specific range of the Reynolds number. In some embodiments, the specific range of the Reynolds number is greater than or equal to approximately 20,000 and less than or equal to approximately 7,000,000. Generally, the Strouhal number corresponding to this range is a substantially constant. Furthermore, in some embodiments, the specific range of the Reynolds number is greater than or equal to approximately 20,000 and less than or equal to approximately 700,000.

[0084] As described above, known vortex flowmeter measurement methods assume the Strouhal number of the fluid 13 to be a constant, resulting in excessively large errors between the estimated flow rate and the fluid flow rate under conditions of low or high fluid flow rate, or when the fluid is mixed with air and the viscosity or density changes due to temperature changes in the fluid production process. In contrast, the measurement and iterative estimation method disclosed herein calculates the estimated flow rate and then calculates the Reynolds number, identifying the interval containing the calculated Reynolds number that conforms to the assumption that the Strouhal number is a constant. This prevents the output of an estimated flow rate with an excessively large error, allowing users to use the measurement and iterative estimation method disclosed herein with confidence, without worrying about distortion of the output resultant flow rate.

[0085] Additionally, the present disclosure also discloses a non-transitory storage medium that stores executable program code. When the executable program code is executed by the vortex flowmeter, the above-described measurement and iterative calculation estimation method is performed. For example, steps S01 to S07 and / or steps S11 to S15 are stored in the non-transitory storage medium in the form of executable program code. When the vortex flowmeter is started, the executable program code in the non-transitory storage medium can be executed, and the measured and estimated flow velocity is calculated according to steps S01 to S07 and / or steps S11 to S15.

[0086] As described above, known vortex flowmeter measurement methods assume the Strouhal number of the fluid to be a constant. This results in excessively large errors between the estimated flow rate and the fluid flow rate at low or high fluid flow rates, or when the fluid contains air and the viscosity or density changes due to temperature changes in the fluid production process. In contrast, the fluid flow rate measurement and iterative estimation method and non-transitory storage medium disclosed herein automatically calculate the estimated flow rate and then further calculate the Reynolds number, thereby identifying whether the interval containing the Reynolds number conforms to the assumption that the Strouhal number is a constant. This prevents the output of an estimated flow rate with an excessively large error as the resultant flow rate. If the interval containing the Reynolds number does not conform to the assumption that the Strouhal number is a constant, the Strouhal number can be adjusted using an iterative calculation method using the estimated fluid flow rate, thereby converging the estimated flow rate to the fluid flow rate. This allows the vortex flowmeter to accurately calculate the fluid flow rate at low or high fluid flow rates. By using the fluid flow velocity measurement and iterative calculation estimation method using a vortex flowmeter and the non-transitory storage medium disclosed herein, a user can automatically obtain a more accurate fluid flow velocity.

[0087] As used herein, and unless otherwise defined, terms such as "substantially" and "approximately" are used to describe and describe small variations. When combined with an event or circumstance, the term can include the exact time at which the event or circumstance occurred, as well as the approximate time from the time at which the event or circumstance occurred. For example, when combined with a numerical value, the term can include cases where the range of variation is ±10% or less of the numerical value, such as ±5% or less, ±4% or less, ±3% or less, ±2% or less, ±1% or less, ±0.5% or less, ±0.1% or less, or ±0.05% or less.

[0088] The above is a brief description of some exemplary embodiments to allow those skilled in the art to better understand the concepts of the exemplary embodiments of the present invention. Those skilled in the art should understand that other manufacturing processes and structures can be designed or modified based on the exemplary embodiments of the present invention to achieve the same objectives and / or advantages as the exemplary embodiments described herein. Those skilled in the art should also understand that these equivalent structures do not depart from the spirit and scope of the present invention, and that various modifications, substitutions, and other alternatives can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined in accordance with the scope of the appended claims. [Explanation of symbols]

[0089] 1 Vortex flow meter 10 Instrument body 101 Piping 102 Mechanical Sensors 103 Piezoelectric element 104 Temperature Sensor 105 Display 11 Column 111 Column width 12 Pipe diameter 13 Fluid 14. Vortex D direction

Claims

1. A method for measuring and iteratively estimating fluid flow velocity using a vortex flowmeter, comprising: measuring a differential pressure fluctuation frequency of a vortex in the first fluid; Obtaining the Nth Strouhal number; obtaining an Nth estimated flow velocity based on the Nth Strouhal number and the differential pressure fluctuation frequency of the vortex; obtaining an Nth Reynolds number of the first fluid based on the Nth estimated flow velocities; Obtaining a Reynolds number-Strouhal number correspondence table; acquiring the (N+1)th Strouhal number based on the Reynolds number-Strouhal number correspondence table and the Nth Reynolds number; and obtaining an (N+1)th estimated flow velocity based on the (N+1)th Strouhal number and the differential pressure fluctuation frequency of the vortex; The method where N is a positive integer.

2. Obtaining the N Reynolds number of the first fluid based on the N estimated flow velocities includes: Obtaining the kinematic viscosity and density of the first fluid based on the temperature and pressure of the first fluid; and The measurement and iterative estimation method of claim 1 , further comprising: obtaining the N Reynolds number of the first fluid based on the kinematic viscosity, the density, and the N inferred flow velocities.

3. The measurement and iterative estimation method of claim 1 , further comprising: calculating an error value based on the N+1 guessed flow rate and the N guessed flow rate.

4. The measurement and iterative estimation method of claim 3 further comprising comparing the error value with a threshold value.

5. The measurement and iterative estimation method of claim 4 , further comprising: outputting the N+1 estimated flow speed as a resultant flow speed if the error value is less than or equal to the threshold value.

6. obtaining an N+1 Reynolds number of the first fluid based on the N+1 estimated flow velocity; searching the Reynolds number-Strouhal number correspondence table for the (N+2)th Strouhal number corresponding to the (N+1)th Reynolds number; and 2. The measurement and iterative calculation estimation method of claim 1, further comprising: obtaining an N+2th estimated flow velocity based on the N+2nd Strouhal number and a differential pressure fluctuation frequency of the vortex.

7. Obtaining the Reynolds number-Strouhal number correspondence table includes: Obtaining a reference Strouhal number and a reference Reynolds number using a second fluid, the second fluid having a predetermined flow velocity; and 2. The measurement and iterative calculation estimation method according to claim 1, further comprising: acquiring the Reynolds number-Strouhal number correspondence table by adjusting the predetermined flow velocity of the second fluid.

8. A method for measuring and iteratively estimating fluid flow velocity using a vortex flowmeter, comprising: Measuring the differential pressure fluctuation frequency of the fluid vortex; Obtaining the Strouhal number, obtaining an estimated flow velocity based on the Strouhal number and the differential pressure fluctuation frequency of the vortex; obtaining a Reynolds number for the fluid based on the estimated flow velocity; and If the Reynolds number is within a particular range, outputting the estimated flow velocity as a resultant flow velocity.

9. 9. The measurement and iterative calculation estimation method of claim 8, wherein the specified range is greater than or equal to about 20,000 and less than or equal to about 7,000,000.

10. A non-transitory storage medium having executable program code recorded thereon, A non-transitory storage medium in which the executable program code, when executed by a vortex flowmeter, performs the measurement and iterative estimation method according to claims 1 to 9.

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