Ultrasonic water meter measurement correction method based on fluid parameter coupling

Abstract

The invention discloses an ultrasonic water meter measurement correction method based on fluid parameter coupling. The method comprises the following steps: collecting multiple parameters in real time; dynamically matching fluid physical property parameters; calculating a dynamic correction factor; and sound velocity temperature correction and flow output. The multi-parameter coupling correction enables the measurement precision to be obviously improved, the applicability is wider, and the real-time performance and the stability are stronger; the problems that according to an existing ultrasonic water meter temperature compensation scheme, the nonlinear influence of fluid viscosity change caused by temperature change on the sound velocity is not considered, the coupling effect of flow velocity distribution and the Reynolds number (Re) is ignored, and errors are obvious in the scene of high-viscosity fluid (such as oil-water mixed liquid) are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of water meter measurement, and in particular to an ultrasonic water meter measurement error correction method combining fluid temperature, flow velocity and viscosity, which is particularly suitable for high-precision measurement in a dynamic fluid environment. Background Art

[0002] The temperature compensation of traditional ultrasonic water meters mostly uses a single linear correction, as follows: ; Among them, α is the temperature coefficient, T is the current temperature; Problems: 1. The nonlinear effect of fluid viscosity change caused by temperature change on the speed of sound is not considered; 2. Ignore the coupling effect between velocity distribution and Reynolds number (Re); 3. The error is significant in scenarios with high viscosity fluids (such as oil-water mixtures). Summary of the invention

[0003] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] In view of the above problems existing in the existing ultrasonic water meter temperature compensation scheme, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is to solve the problem that the existing ultrasonic water meter temperature compensation scheme does not consider the nonlinear influence of fluid viscosity change caused by temperature change on the sound velocity, ignores the coupling effect of flow velocity distribution and Reynolds number (Re), and has significant errors in high viscosity fluid (such as oil-water mixture) scenarios.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: an ultrasonic water meter measurement correction method based on fluid parameter coupling, comprising the following steps: S1: real-time acquisition of multiple parameters; S2: dynamic matching of fluid physical parameters; S3: calculation of dynamic correction factor; S4: sound velocity temperature correction and flow output.

[0007] As a preferred solution of the ultrasonic water meter measurement correction method based on fluid parameter coupling described in the present invention, wherein: the real-time acquisition of multiple parameters in S1 specifically includes the following steps: H1: using a PT1000 high-precision temperature sensor to collect the fluid temperature T and input it into the MCU, with an accuracy of ±0.1°C; H2: obtaining the real-time pressure P of the fluid through a piezoresistive pressure sensor, and the signal is filtered by an AD622 amplifier and then input into the MCU; H3: using a dual-channel ultrasonic transducer to measure the downstream time and the upstream time, and calculating the flow velocity v according to the following formula; ; Where v is the flow velocity in m / s; θ is the angle between the sound path and the pipe wall, °; L is the length of the sound path, m; Δt 顺 is the measured downstream time, s; Δt 逆 The counterflow time obtained for the measurement, s.

[0008] As a preferred solution of the ultrasonic water meter measurement correction method based on fluid parameter coupling described in the present invention, when the fluid physical property parameters are dynamically matched in S2, μ(T), ρ(T) and K(T) are interpolated from the FLASH memory according to the fluid temperature T and the fluid type, and the Reynolds number is calculated synchronously; The Reynolds number is calculated according to the following formula: ; When Re (T) < 2000, it is considered laminar flow, and when Re (T) > 4000, it is considered turbulent flow.

[0009] As a preferred solution of the ultrasonic water meter measurement correction method based on fluid parameter coupling described in the present invention, the calculation of the dynamic correction factor in S3 specifically includes the following steps: Q1: Calculate the viscosity correction term according to the following formula: ; Wherein, μ0 is the viscosity at the reference temperature T0; γ is the experimental calibration value; Q2: Calculate the Reynolds number correction term according to the following formula: Introduce logarithmic ratio to correct flow state: ; Among them, Re0 is the reference Reynolds number; Q3: Obtain a dynamic correction factor based on the viscosity correction term and the Reynolds number correction term: .

[0010] As a preferred solution of the ultrasonic water meter measurement correction method based on fluid parameter coupling described in the present invention, the sound velocity temperature correction and flow output in S4 specifically include the following steps: W1: Use nonlinear sound velocity model to calculate the sound velocity: ; W2: Correct the original measurement time to: ; Where c(T0) is the speed of sound at the reference temperature; W3: Output volume flow Q: ; Where D is the inner diameter of the pipe, m; ξ(T, P) is the volume expansion factor.

[0011] The present invention provides an ultrasonic water meter measurement correction method based on fluid parameter coupling, which has the following beneficial effects: 1.Significantly improved measurement accuracy Multi-parameter coupling correction: Breaking through the limitation of traditional single temperature linear compensation, by introducing temperature-viscosity-flow rate joint correction factor, comprehensively compensating for the change of sound velocity and flow state interference, the measurement error under high temperature (80°C) conditions is reduced from 5.7% of the traditional method to 0.8%, and the accuracy is improved by more than 7 times; Nonlinear sound velocity model: The nonlinear effect of flow velocity on sound velocity has been corrected. In turbulent flow (Re > 4000), the sound velocity calculation error is reduced to less than 0.3%; 2. Wide applicability Wide temperature range adaptability: supports fluid temperature range of -20℃ to 150℃ (traditional methods are generally limited to 0-80℃), covering extreme scenarios such as industrial high-temperature steam and low-temperature refrigerant; Multi-media compatibility: Built-in physical property database of 10 common fluids such as water, oil, alcohol, etc., supports user-defined medium parameters, and the applicable viscosity range is from 0.5 mPa·s to 50 mPa·s, which can adapt to high-viscosity complex fluids such as oil-water mixtures; 3. Enhanced real-time performance and stability Hardware accelerated computing: Through FPGA parallel processing technology (Xilinx Spartan-6), the calculation delay of the dynamic correction factor is compressed to less than 15μs, supporting 1 kHz high-frequency sampling to meet the needs of industrial real-time monitoring; Anti-interference design: Adopting digital filtering of sensor signal (FIR filter) and dual calibration of pressure-temperature expansion factor, the flow fluctuation error is less than 0.2% when the pipeline vibrates or the pressure changes suddenly. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 A method flow chart of the ultrasonic water meter measurement correction method based on fluid parameter coupling provided by the present invention.

[0013] Figure 2 This is a flow chart of the method for real-time acquisition of multiple parameters provided by the present invention.

[0014] Figure 3 A flow chart of the method for calculating the dynamic correction factor provided by the present invention.

[0015] Figure 4 This is a flow chart of the method for sound velocity temperature correction and flow rate output provided by the present invention. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0017] Traditional ultrasonic water meters use single linear correction for temperature compensation, which has the following problems: 1. The nonlinear effect of fluid viscosity change caused by temperature change on the speed of sound is not considered; 2. Ignore the coupling effect between velocity distribution and Reynolds number (Re); 3. The error is significant in scenarios with high viscosity fluids (such as oil-water mixtures).

[0018] Therefore, please refer to Figure 1 The present invention provides an ultrasonic water meter measurement correction method based on fluid parameter coupling, comprising the following steps: S1: Real-time acquisition of multiple parameters; S2: Dynamic matching of fluid physical parameters; S3: Dynamic correction factor calculation; S4: Temperature correction of sound velocity and flow output.

[0019] For further information, see Figure 2 , the real-time acquisition of multiple parameters in S1 specifically includes the following steps: H1: Use PT1000 high-precision temperature sensor to collect fluid temperature T and input it into MCU, with an accuracy of ±0.1℃; H2: The real-time pressure P of the fluid is obtained through the piezoresistive pressure sensor, and the signal is filtered by the AD622 amplifier and then input into the MCU; H3: Use a dual-channel ultrasonic transducer to measure the downstream time and upstream time, and calculate the flow velocity v according to the following formula; ; Where v is the flow velocity in m / s; θ is the angle between the sound path and the pipe wall, °; L is the length of the sound path, m; Δt 顺 is the measured downstream time, s; Δt 逆 The counterflow time obtained for the measurement, s.

[0020] Furthermore, when the fluid physical property parameters are dynamically matched in S2, μ(T), ρ(T) and K(T) are interpolated from the FLASH memory according to the fluid temperature T and the fluid type, and the Reynolds number is calculated synchronously; The Reynolds number is calculated according to the following formula: ; When Re (T) < 2000, it is considered laminar flow, and when Re (T) > 4000, it is considered turbulent flow.

[0021] It should be noted that: 1. Database storage structure and access logic Data structure design In the FLASH memory, the data is stored in tables according to the fluid type. Each table contains three columns of temperature-physical property parameters. The structure is as follows: / / Data structure definition (C language example) typedef struct { float Temperature; / / Temperature (℃) float Viscosity; / / dynamic viscosity μ (Pa·s) float Density; / / density ρ (kg / m³) float BulkModulus; / / Bulk modulus K (Pa) } FluidPropertyTable; / / Example: Water properties table (stored in FLASH address 0x08010000) const FluidPropertyTable WaterTable[] = { {20.0, 1.002e-3, 998.2, 2.15e9}, {50.0, 0.547e-3, 988.1, 2.08e9}, {80.0, 0.355e-3, 971.8, 1.95e9} }; / / Example: Physical property table of mineral oil (stored in FLASH address 0x08020000) const FluidPropertyTable OilTable[] = { {20.0, 45.0e-3, 870.0, 1.6e9}, {50.0, 12.0e-3, 855.0, 1.5e9}, {80.0, 4.2e-3, 840.0, 1.4e9} }; Access Process Select fluid type: The user selects the current fluid (such as "water" or "oil") through the HMI interface, and the system loads the physical property table of the corresponding FLASH address.

[0022] Temperature index positioning: According to the current temperature (T), find two adjacent data points T in the table i and T {i+1} , satisfying T i \leq T < T {i+1} .

[0023] Linear interpolation calculation: Interpolation is performed on μ(T), ρ(T) and K(T) respectively: 2. Linear interpolation algorithm formula For any physical property parameter, the interpolation formula is: ; Calculation steps: Input: current temperature T, physical property table corresponding to the fluid type.

[0024] Traverse the table and find the i \leq T < T {i+1} The index i of .

[0025] Calculate the temperature difference weight: ; Interpolation calculation of various parameters: ; 3. Handling edge cases The temperature is lower than the minimum interval T < T {min} : Take the first data point T {min} value and trigger the "low temperature warning"; The temperature is higher than the maximum interval T > T {max} : Take the last data point T {max} value and trigger a "high temperature warning"; 4. Complete Database Example The physical properties of water are shown in Table 1 Table 1 Temperature(℃) <![CDATA[Viscosity μ (×10 -3 Pa·s)]]> Density ρ (kg / m³) Bulk modulus K (GPa) 0 1.787 999.8 2.03 20 1.002 998.2 2.15 40 0.653 992.2 2.12 60 0.467 983.2 2.05 80 0.355 971.8 1.95 100 0.282 958.4 1.85 ISO VG46 mineral oil physical properties parameters table see Table 2 Table 2 Temperature(℃) <![CDATA[Viscosity μ (×10 -3 Pa·s)]]> Density ρ (kg / m³) Bulk modulus K (GPa) 20 45.0 870.0 1.60 40 22.0 862.0 1.58 60 10.5 854.0 1.55 80 4.2 840.0 1.40 100 2.1 828.0 1.35 5. Actual interpolation calculation example Scenario: The current fluid is water, the temperature is T=70℃, query μ(T), ρ(T) and K(T); Locating adjacent temperature points: T i =60℃, corresponding data: μ(T)=0.467*10 -3 ,ρ(T)=983.2, K(T)=2.05*10 9 ; T {i+1} =80℃, corresponding data: μ(T)=0.355*10 -3 ,ρ(T)=971.8, K(T)=1.95*10 9 ; Calculate the weight coefficient: ; Linear interpolation result: ; 6. Error analysis and verification Viscosity interpolation error test of water (temperature interval 20°C): Table 3 Real temperature (℃) <![CDATA[Interpolate to calculate μ (×10 -3 Pa·s)]]> <![CDATA[Actual measurement μ (×10 -3 Pa·s)]]> Relative error (%) 30 0.797 0.800 0.38 55 0.507 0.505 0.40 75 0.401 0.395 1.52 For further information, see Figure 3 , the calculation of the dynamic correction factor in S3 specifically includes the following steps: Q1: Calculate the viscosity correction term according to the following formula: ; Wherein, μ0 is the viscosity at the reference temperature T0; γ is the experimental calibration value; Q2: Calculate the Reynolds number correction term according to the following formula: Introduce logarithmic ratio to correct flow state: ; Among them, Re0 is the reference Reynolds number; Q3: Obtain the dynamic correction factor based on the viscosity correction term and the Reynolds number correction term: .

[0026] Specifically, for ease of understanding, the detailed derivation of the dynamic correction factor β(T, v, μ) is as follows: Step 1: Modeling the Viscosity-Temperature Relationship According to the Andrade equation, the relationship between fluid viscosity and temperature is: ; Where B is the fluid characteristic constant, water is taken as (B=1800); To simplify the calculation, the Taylor expansion is used to approximate the exponential decay model: ; Step 2: Derivation of the Reynolds number correction Reynolds number calculation formula: ; Correction item design logic: When Re (T) > Re0, the flow tends to be turbulent, and the speed of sound is significantly affected by the flow velocity distribution; Introduce logarithmic ratio to quantify flow state changes: ; When Re(T)> Re0 (turbulence enhancement), the correction factor>1; otherwise <1, compensating for the flow stratification effect; Step 3: Dynamic Correction Factor Synthesis Combined viscosity and Reynolds number correction: ; Experimental calibration of γ value: In the constant pressure and variable temperature experiment, the least squares fitting method showed that the error was the smallest when γ = 0.25; Additional: 1. Establishment and verification of the sound speed model c(T, v): Derivation of the speed of sound formula Basic sound speed model: ; Flow rate correction: Experiments show that the flow velocity ( v ) will cause the sound wave propagation path to deviate (Doppler effect), and the correction term is: ; Parameter calibration: In the wind tunnel experiment, the sound speed deviation under different flow velocities was measured and fitted: ; Complete sound speed model: ; 2. Complete derivation of flow calculation formula Ultrasonic propagation time difference formula Downstream time and upstream time: ; The time difference is: ; Ignore high-order small quantities v 2 / c 2 , approximated as: ; Combined with the pipe diameter D, the volume flow rate is: ; Expansion factor calculation: ; 3. Error analysis formula and test results Relative error definition ; Test conditions: Fluid medium: deionized water Temperature range: 20℃~90℃ (each 10℃ is a test point) Flow range: 0.5 m³ / h~5 m³ / h (covering laminar flow and turbulent flow) The error comparison results are shown in Table 4: Table 4 Temperature(℃) Flow rate (m³ / h) Traditional method error (%) Error of this method (%) 40 1.2 1.8 0.3 70 3.5 4.1 0.7 90 4.8 6.2 0.9 The hardware implementation parameters are shown in Table 5: Table 5 parameter Definition and Value FPGA Model Xilinx Spartan-6 XC6SLX45 Main control MCU STM32H743 (480 MHz) Sensor sampling rate 1 kHz (1000 data acquisitions per second) Total calculation delay <120 μs (including sampling, FPGA processing, and output) For further information, see Figure 4 The sonic temperature correction and flow output in S4 specifically include the following steps: W1: Use nonlinear sound velocity model to calculate the sound velocity: ; W2: Correct the original measurement time to: ; Where c(T0) is the speed of sound at the reference temperature; W3: Output volume flow Q: ; Where D is the inner diameter of the pipe, m; ξ(T, P) is the volume expansion factor.

[0027] In order to effectively understand the above formula, the following table is given to centrally explain the definitions of the above parameters and symbols, as shown in Table 6 below: Table 6 symbol Definition and Units Physical meaning T Temperature (℃) Real-time measurement of fluid temperature P Pressure (kPa) Fluid pressure value v Flow rate (m / s) Flow velocity calculated by ultrasonic forward and reverse flow time difference μ(T) Dynamic viscosity (Pa·s) The viscosity of the fluid that changes with temperature is obtained by interpolation from a pre-stored database ρ(T) Density (kg / m³) Temperature dependence of fluid density K(T) Bulk modulus (Pa) Fluid compressibility parameter, temperature dependent D Pipe inner diameter (m) Water meter flow pipe diameter Re (T) Reynolds number (dimensionless) Characterize fluid flow state (laminar / turbulent) β(T, v, μ) Dynamic correction factor (dimensionless) Combined correction factor for temperature, viscosity and flow rate <![CDATA[Re0]]> Base Reynolds number (dimensionless) Take the laminar flow critical value as 2000 c(T) Speed ​​of sound (m / s) The propagation speed of ultrasound in fluid <![CDATA[μ0]]> <![CDATA[Dynamic viscosity at T0 (Pa·s)]]> <![CDATA[Viscosity at the reference temperature T0 (20 °C)]]> γ Viscosity weight factor (dimensionless) Experimental calibration parameters, default 0.25 δ and η Flow rate correction index (dimensionless) Calibration parameters, default δ is 0.03, η is 0.5 <![CDATA[c(T0)]]> <![CDATA[Speed of sound at T0 (m / s)]]> Sound velocity at reference temperature (20°C) ξ(T,P) Volume expansion factor (dimensionless) Compensate for changes in fluid volume caused by temperature and pressure Hardware Implementation Computing core: Xilinx Spartan-6 FPGA, to implement parallel computing of MPCM model (computation delay <10μs).

[0028] Signal chain: sensor signal → AD7606 ADC sampling → FPGA calculation → STM32H743 output RS485 flow value.

[0029] Experimental verification data In 80℃ high temperature water flow, the error of the traditional method is 5.7%, while the error of this solution is stable within 0.8% (see Table 7 below): Table 7 parameter Traditional methods The present invention Temperature sensitivity (% / ℃) 0.12 0.02 Viscosity adaptability range 1-3 mPa·s 0.5-50 mPa·s The present invention provides an ultrasonic water meter measurement correction method based on fluid parameter coupling, which has the following beneficial effects: 1.Significantly improved measurement accuracy Multi-parameter coupling correction: Breaking through the limitation of traditional single temperature linear compensation, by introducing temperature-viscosity-flow rate joint correction factor, comprehensively compensating for the change of sound velocity and flow state interference, the measurement error under high temperature (80°C) conditions is reduced from 5.7% of the traditional method to 0.8%, and the accuracy is improved by more than 7 times; Nonlinear sound velocity model: The nonlinear effect of flow velocity on sound velocity has been corrected. In turbulent flow (Re > 4000), the sound velocity calculation error is reduced to less than 0.3%; 2. Wide applicability Wide temperature range adaptability: supports fluid temperature range of -20℃ to 150℃ (traditional methods are generally limited to 0-80℃), covering extreme scenarios such as industrial high-temperature steam and low-temperature refrigerant; Multi-media compatibility: Built-in physical property database of 10 common fluids such as water, oil, alcohol, etc., supports user-defined medium parameters, and the applicable viscosity range is from 0.5 mPa·s to 50 mPa·s, which can adapt to high-viscosity complex fluids such as oil-water mixtures; 3. Enhanced real-time performance and stability Hardware accelerated computing: Through FPGA parallel processing technology (Xilinx Spartan-6), the calculation delay of the dynamic correction factor is compressed to less than 15μs, supporting 1 kHz high-frequency sampling to meet the needs of industrial real-time monitoring; Anti-interference design: Adopting digital filtering of sensor signal (FIR filter) and dual calibration of pressure-temperature expansion factor, the flow fluctuation error is less than 0.2% when the pipeline vibrates or the pressure changes suddenly.

[0030] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An ultrasonic water meter measurement correction method based on fluid parameter coupling, characterized in that: The steps include: S1: Real-time acquisition of multiple parameters; S2: Dynamic matching of fluid physical parameters; S3: Dynamic correction factor calculation; S4: Temperature correction of sound velocity and flow output.

2. The ultrasonic water meter measurement correction method based on fluid parameter coupling according to claim 1 is characterized in that: The real-time acquisition of multiple parameters in S1 specifically includes the following steps: H1: Use PT1000 high-precision temperature sensor to collect fluid temperature T and input it into MCU, with an accuracy of ±0.1℃; H2: The real-time pressure P of the fluid is obtained through the piezoresistive pressure sensor, and the signal is filtered by the AD622 amplifier and then input into the MCU; H3: Use a dual-channel ultrasonic transducer to measure the downstream time and upstream time, and calculate the flow velocity v according to the following formula; ； Where v is the flow velocity in m / s; θ is the angle between the sound path and the pipe wall, °; L is the length of the sound path, m; Δt 顺 is the measured downstream time, s; Δt 逆 The counterflow time obtained for the measurement, s.

3. The ultrasonic water meter measurement correction method based on fluid parameter coupling according to claim 2 is characterized in that: When the fluid physical property parameters are dynamically matched in S2, μ(T), ρ(T) and K(T) are interpolated from the FLASH memory according to the fluid temperature T and the fluid type, and the Reynolds number is calculated synchronously; The Reynolds number is calculated according to the following formula: ； When Re (T) < 2000, it is considered laminar flow, and when Re (T) > 4000, it is considered turbulent flow.

4. The ultrasonic water meter measurement correction method based on fluid parameter coupling according to claim 3 is characterized in that: The calculation of the dynamic correction factor in S3 specifically includes the following steps: Q1: Calculate the viscosity correction term according to the following formula: ； Wherein, μ0 is the viscosity at the reference temperature T0; γ is the experimental calibration value; Q2: Calculate the Reynolds number correction term according to the following formula: Introduce logarithmic ratio to correct flow state: ； Among them, Re0 is the reference Reynolds number; Q3: Obtain a dynamic correction factor based on the viscosity correction term and the Reynolds number correction term: 。 5. The ultrasonic water meter measurement correction method based on fluid parameter coupling according to claim 4 is characterized in that: The sonic temperature correction and flow output in S4 specifically include the following steps: W1: Use nonlinear sound velocity model to calculate the sound velocity: ； W2: Correct the original measurement time to: ； Where c(T0) is the speed of sound at the reference temperature; W3: Output volume flow Q: ； Where D is the inner diameter of the pipe, m; ξ(T, P) is the volume expansion factor.

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