Ultrasonic gas meter verification method based on instantaneous flow method

Abstract

The embodiment of the invention discloses an ultrasonic gas meter verification method based on an instantaneous flow method. Performing time synchronization on the flow standard device and the ultrasonic gas meter; adjusting the flow to a to-be-detected flow point according to the control instruction; obtaining measurement values under the working conditions at the same moment; whether abnormal flow exists or not is judged according to the to-be-detected flow point of the instantaneous flow value of the flow standard device, and if yes, an alarm signal is sent out; performing dynamic compensation according to the measured value under the working condition to obtain an instantaneous flow value of the flow standard device under the standard condition; according to the instantaneous flow value of the ultrasonic gas meter under the working condition, the temperature value of the ultrasonic gas meter under the working condition and the pressure value of the ultrasonic gas meter under the working condition, the instantaneous flow value of the ultrasonic gas meter under the standard condition is obtained; and obtaining the indication error of the ultrasonic gas meter under the standard condition according to the instantaneous flow value of the flow standard device under the standard condition and the instantaneous flow value of the ultrasonic gas meter under the standard condition.

Description

Technical Field

[0001] This invention relates to the field of gas meter measurement. More specifically, it relates to an ultrasonic gas meter calibration method based on the instantaneous flow rate method. Background Technology

[0002] Currently, gas meters serve as crucial measuring instruments and the basis for natural gas metering and trade settlement, making their accuracy paramount. For traditional diaphragm gas meters, testing institutions commonly use cumulative flow method standard devices for gas flow measurement, employing LED signal acquisition for signal acquisition and error determination. However, for ultrasonic gas meters, the cumulative flow method suffers from limitations in testing efficiency and accuracy due to the lag caused by pulse rounding, making it difficult to meet the higher efficiency and accuracy requirements of ultrasonic gas meter calibration. To address this issue, the instantaneous flow method can be used to calibrate ultrasonic gas meters.

[0003] The instantaneous flow rate method involves collecting the instantaneous flow rate value of an ultrasonic gas meter at a specific moment during calibration and comparing it with the instantaneous flow rate value of a flow standard device at the same moment, then determining the error. Because the instantaneous flow rate of gas is complex, even minor changes in environmental factors such as temperature, pressure, density, and external interference can cause variations in the instantaneous flow rate, leading to significant errors in the measured value. Delayed response to acquisition commands and time synchronization errors can cause the instantaneous flow rates collected by the ultrasonic gas meter and the flow standard device to not be strictly at the same moment. These shortcomings result in the traditional instantaneous flow rate method typically having lower calibration accuracy and repeatability than the cumulative flow rate method, limiting its application in ultrasonic gas meter calibration. Therefore, there is an urgent need for an improved instantaneous flow rate calibration technology that balances efficiency and accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide an ultrasonic gas meter calibration method based on the instantaneous flow rate method, so as to solve at least one of the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention provides a method for calibrating an ultrasonic gas meter based on the instantaneous flow rate method, comprising: Time synchronization between the flow standard device and the ultrasonic gas meter; Adjust the flow rate to the flow point to be detected according to the control command; The instantaneous flow rate, temperature, and pressure values ​​of the flow rate standard device under the same operating conditions are obtained at the same time. Based on the instantaneous flow value of the flow standard device, the flow point to be detected is judged to determine whether there is abnormal flow. If so, an alarm signal is issued. The instantaneous flow rate of the flow standard device under standard conditions is obtained by dynamic compensation based on the instantaneous flow rate value, temperature value, and pressure value of the flow standard device under standard conditions. The instantaneous flow rate of the ultrasonic gas meter under standard conditions is obtained from the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter under operating conditions. The indication error of the ultrasonic gas meter under standard conditions is obtained based on the instantaneous flow value of the flow standard device under standard conditions and the instantaneous flow value of the ultrasonic gas meter under standard conditions.

[0006] Optionally, determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: If the instantaneous flow rate value of the flow rate standard device is less than the minimum value of the flow rate point to be detected, and the instantaneous flow rate value of the flow rate standard device is greater than 0, then there is a small flow rate.

[0007] Optionally, determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: If the instantaneous flow rate value of the flow rate standard device is greater than the maximum value of the flow rate point to be detected, then there is an overload flow rate.

[0008] Optionally, determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: If the instantaneous flow rate value of the flow rate standard device is less than 0, then there is reverse flow.

[0009] Optionally, the calculation formula for obtaining the instantaneous flow rate of the flow standard device under standard conditions by dynamically compensating based on the instantaneous flow rate value, temperature value, and pressure value of the flow standard device under operating conditions is as follows:

[0010] In the formula, This refers to the instantaneous flow rate value of the flow standard device under standard conditions; The instantaneous flow rate value of the flow standard device under operating conditions; The temperature value of the flow rate standard device under operating conditions; The pressure value of the flow rate standard device under operating conditions; The temperature value of the flow rate standard device under standard conditions; The pressure value of the flow standard device under operating conditions.

[0011] Optionally, the formula for calculating the instantaneous flow rate of the ultrasonic gas meter under standard conditions based on the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter under operating conditions is as follows:

[0012] In the formula, This represents the instantaneous flow rate of the ultrasonic gas meter under standard conditions. This represents the instantaneous flow rate of the ultrasonic gas meter under operating conditions. The temperature value of the ultrasonic gas meter under operating conditions; This represents the pressure value of the ultrasonic gas meter under operating conditions.

[0013] Optionally, the formula for calculating the indication error of the ultrasonic gas meter under standard conditions based on the instantaneous flow rate value of the flow standard device under standard conditions and the instantaneous flow rate value of the ultrasonic gas meter under standard conditions is as follows:

[0014] In the formula, This represents the indication error of the ultrasonic gas meter under standard conditions.

[0015] Optionally, the formula for calculating the instantaneous flow rate of the ultrasonic gas meter under the aforementioned operating conditions is as follows:

[0016] In the formula, This represents the cross-sectional area of ​​the gas flow. The velocity of the gas flow.

[0017] Optionally, the formula for calculating the velocity of the gas flow is:

[0018] In the formula, The length of the ultrasonic wave propagation in the flow channel; The angle between the gas flow direction and the transducer direction; The first time of transmission; This is the second transmission time.

[0019] Optionally, the formula for calculating the first propagation time is:

[0020] The formula for calculating the second propagation time is:

[0021] In the formula, The speed of sound.

[0022] The beneficial effects of this invention are as follows: The technical solution described in this invention, while maintaining the high efficiency advantage of the instantaneous flow rate method, significantly improves its calibration accuracy and reliability; when using the instantaneous flow rate method to calibrate ultrasonic gas meters, it improves calibration efficiency and reduces indication errors; it solves the problem that when using the instantaneous flow rate method to calibrate ultrasonic gas meters, the measurement indication error is too large due to the influence of flow field fluctuations, response delays, and time synchronization errors. Attached Figure Description

[0023] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0024] Figure 1 This diagram illustrates a flowchart of an ultrasonic gas meter calibration method based on the instantaneous flow rate method provided in an embodiment of the present invention.

[0025] Figure 2 This diagram illustrates another flowchart of the ultrasonic gas meter calibration method based on the instantaneous flow rate method provided in an embodiment of the present invention.

[0026] Figure 3 This diagram illustrates an ultrasonic gas meter calibration system based on the instantaneous flow rate method provided in an embodiment of the present invention. Detailed Implementation

[0027] To more clearly illustrate the present invention, the following description, in conjunction with embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0028] The instantaneous flow rate method involves collecting the instantaneous flow rate value of an ultrasonic gas meter at a specific moment during calibration and comparing it with the instantaneous flow rate value of a flow standard device at the same moment, then determining the error. Because the instantaneous flow rate of gas is complex, even minor changes in environmental factors such as temperature, pressure, density, and external interference can cause variations in the instantaneous flow rate, leading to significant errors in the measured value. Delayed response to acquisition commands and time synchronization errors can cause the instantaneous flow rates collected by the ultrasonic gas meter and the flow standard device to not be strictly at the same moment. These shortcomings result in the traditional instantaneous flow rate method typically having lower calibration accuracy and repeatability than the cumulative flow rate method, limiting its application in ultrasonic gas meter calibration. Therefore, there is an urgent need for an improved instantaneous flow rate calibration technology that balances efficiency and accuracy.

[0029] In view of this, such as Figure 1As shown, one embodiment of the present invention provides a method for calibrating an ultrasonic gas meter based on the instantaneous flow rate method, comprising: synchronizing a flow standard device and an ultrasonic gas meter in time; adjusting the flow rate to the flow point to be tested according to a control command; acquiring the instantaneous flow rate value of the flow standard device, the temperature value of the flow standard device, the pressure value of the flow standard device, the instantaneous flow rate value of the ultrasonic gas meter, the temperature value of the ultrasonic gas meter, and the pressure value of the ultrasonic gas meter at the same time under operating conditions; and determining whether there is an anomaly at the flow point to be tested based on the instantaneous flow rate value of the flow standard device. A constant flow rate is established; if present, an alarm signal is issued. The instantaneous flow rate of the standard flow rate device is obtained through dynamic compensation based on the instantaneous flow rate, temperature, and pressure values ​​of the standard flow rate device under operating conditions. The instantaneous flow rate of the ultrasonic gas meter under standard conditions is obtained based on the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter under operating conditions. The indication error of the ultrasonic gas meter under standard conditions is obtained based on the instantaneous flow rate of the standard flow rate device and the instantaneous flow rate of the ultrasonic gas meter under standard conditions.

[0030] In a specific example, the gas temperature and pressure values ​​inside the flow standard device and ultrasonic gas meter cavity are monitored in real time; a real-time dynamic error compensation model is established based on the real-time monitored pressure and temperature values ​​for adaptive correction; a closed-loop feedback control method is used to quickly stabilize the flow field; and an intelligent diagnostic module is integrated to monitor the gas flow rate in real time during the calibration process and analyze whether there are any abnormalities.

[0031] In a specific example, such as Figure 2 As shown, Step 1: Start the flow standard device system, control the gas path to a stable state, and the flow standard device performs self-calibration. Install the ultrasonic gas meter under test on the fixture, and the system synchronizes the sonic nozzle standard flow device and the ultrasonic gas meter in time. Select the required flow points Qmin, 3Qmin, 5Qmin, 10Qmin, 0.1Qmax, 0.2Qmax, 0.4Qmax, 0.7Qmax, and Qmax according to the verification procedure.

[0032] Further, in step 2: the intelligent flow control system issues a control command to quickly reach the first flow point to be detected, Qmin, and maintain it at a very high stability. After detecting one flow point, the flow is sequentially adjusted to the next flow point to be detected: 3Qmin, 5Qmin, 10Qmin, 0.1Qmax, 0.2Qmax, 0.4Qmax, 0.7Qmax, and Qmax.

[0033] Further, step 3: Collect the instantaneous flow rate value Q of the sonic nozzle standard flow meter. r Temperature T r Pressure value P r The instantaneous flow rate Q of the ultrasonic gas meter under test m Temperature T m Pressure value P m .

[0034] Further, in step 4: the dynamic error compensation module compensates for the instantaneous flow values ​​of the sonic nozzle standard flow device and the ultrasonic gas meter to obtain the instantaneous flow values ​​under standard conditions, calculates the indication error, and records it.

[0035] Further, in step 5: the system automatically switches to the next flow rate point and repeats steps S1-S4 until all preset points are verified. After the test is completed, a verification report containing data comparisons and error curves for each flow rate point is automatically generated.

[0036] In a specific example, the intelligent flow standard device system synchronizes the ultrasonic gas meter and the sonic nozzle flow standard device, and then collects the instantaneous flow value Q of the sonic nozzle flow standard device at the same time. r The instantaneous flow rate Q of the ultrasonic gas meter under test m This avoids errors caused by asynchronous collection times or response delays, which result in the instantaneous traffic being collected at different times.

[0037] Furthermore, the intelligent flow standard device system sends a time synchronization command to synchronize the ultrasonic gas meter and the sonic nozzle standard flow device, ensuring that the instantaneous flow values ​​collected during the calibration process are values ​​from the same moment.

[0038] The technical solution described in this invention, while maintaining the high efficiency advantage of the instantaneous flow rate method, significantly improves its calibration accuracy and reliability; when using the instantaneous flow rate method to calibrate ultrasonic gas meters, it improves calibration efficiency and reduces indication errors; it solves the problem that when using the instantaneous flow rate method to calibrate ultrasonic gas meters, the measurement indication error is too large due to the influence of flow field fluctuations, response delays, and time synchronization errors.

[0039] In one possible implementation, determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: if the instantaneous flow value of the flow standard device is less than the minimum value of the flow point to be detected, and the instantaneous flow value of the flow standard device is greater than 0, then there is a small flow.

[0040] In one possible implementation, determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: if the instantaneous flow value of the flow standard device is greater than the maximum value of the flow point to be detected, then there is overload flow.

[0041] In one possible implementation, determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: if the instantaneous flow value of the flow standard device is less than 0, then there is reverse flow.

[0042] In a specific example, the intelligent diagnostic module monitors abnormal flow in real time and analyzes the instantaneous flow value Q of the sonic nozzle standard flow device in real time. r The instantaneous flow rate Q of the ultrasonic gas meter under test m When Q r min And Q r If Q > 0, it is considered that a small flow exists; when Q r Q max Then it is assumed that there is an overload flow; when Q r If the value is less than 0, reverse flow is considered to exist. Abnormal flow will be promptly reported to the intelligent flow control system and an alert will be issued.

[0043] In one possible implementation, the formula for calculating the instantaneous flow rate of the flow standard device under operating conditions by dynamically compensating for the instantaneous flow rate of the flow standard device under operating conditions, the temperature value of the flow standard device under operating conditions, and the pressure value of the flow standard device under operating conditions is as follows:

[0044] In the formula, This refers to the instantaneous flow rate value of the flow standard device under standard conditions; The instantaneous flow rate value of the flow standard device under operating conditions; The temperature value of the flow rate standard device under operating conditions; The pressure value of the flow rate standard device under operating conditions; The temperature value of the flow rate standard device under standard conditions is taken as 20°C. The pressure value of the flow standard device under operating conditions is taken as 101.325 kPa.

[0045] In one possible implementation, the formula for calculating the instantaneous flow rate of the ultrasonic gas meter under standard conditions based on the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter under operating conditions is as follows:

[0046] ​In the formula, This represents the instantaneous flow rate of the ultrasonic gas meter under standard conditions. This represents the instantaneous flow rate of the ultrasonic gas meter under operating conditions. The temperature value of the ultrasonic gas meter under operating conditions; This represents the pressure value of the ultrasonic gas meter under operating conditions.

[0047] In a specific example, the dynamic error compensation module dynamically compensates the instantaneous flow values ​​of the sonic nozzle standard flow device and the ultrasonic gas meter in real time, converting the instantaneous flow under operating conditions into the instantaneous flow under standard conditions, eliminating the influence of temperature and pressure changes on the instantaneous flow value, and reducing the indication error of the instantaneous flow.

[0048] In one possible implementation, the formula for calculating the indication error of the ultrasonic gas meter under standard conditions based on the instantaneous flow rate value of the flow standard device under standard conditions and the instantaneous flow rate value of the ultrasonic gas meter under standard conditions is as follows:

[0049] In the formula, This represents the indication error of the ultrasonic gas meter under standard conditions.

[0050] In a specific example, the formula for calculating the indication error of an ultrasonic gas meter under standard conditions is modified as follows:

[0051] In one possible implementation, the formula for calculating the instantaneous flow rate of the ultrasonic gas meter under the aforementioned operating conditions is as follows:

[0052] In the formula, This represents the cross-sectional area of ​​the gas flow. The velocity of the gas flow.

[0053] In one possible implementation, the formula for calculating the velocity of the gas flow is:

[0054] In the formula, The length of the ultrasonic wave propagation in the flow channel; The angle between the gas flow direction and the transducer direction; The first time of transmission; This is the second transmission time.

[0055] In one possible implementation, the formula for calculating the first propagation time is:

[0056] The formula for calculating the second propagation time is:

[0057] In the formula, The speed of sound.

[0058] In a specific example, ultrasonic gas meters that use the time-of-flight method to calculate flow rate are not suitable for older diaphragm gas meters. The principle of the time-of-flight method for ultrasonic gas meters is as follows: Let the length of the ultrasonic wave propagating in the flow channel be *l*, the gas flow velocity be *V*, and the upstream transducer emits an ultrasonic wave beam, which is received by the downstream transducer. At this time, the ultrasonic wave propagates in the same direction as the gas flow, and the propagation time is *V*. Then, the downstream transducer emits an ultrasonic wave beam, which is received by the upstream transducer. At this time, the ultrasonic wave propagates in the opposite direction to the gas flow, and the propagation time is *V*. The angle between the gas flow direction and the transducer direction, the cross-sectional area of ​​the gas flow, and the sound velocity are calculated using the above formulas.

[0059] In a specific example, the ultrasonic gas meter has an infrared optical interface, using infrared light in the near-infrared band (wavelength 900nm–1000nm) as the information carrier. The intelligent flow standard device system communicates with the ultrasonic gas meter through this near-infrared interface to perform time synchronization and directly read the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter at the same time.

[0060] Another embodiment of the present invention provides an optimized system for calibrating ultrasonic gas meters based on the instantaneous flow rate method, such as... Figure 3 As shown, an intelligent flow standard device system was constructed by adding a high-precision temperature and pressure sensor, an intelligent flow control system, a dynamic error compensation module, and an intelligent diagnostic module to the traditional sonic nozzle standard flow device.

[0061] In a specific example, a sonic nozzle standard flow meter provides the gas source and flow rate; a high-precision sensor monitors the temperature and pressure data of both the sonic nozzle standard flow meter and the ultrasonic gas meter; the intelligent flow control system dynamically adjusts the precision regulating valve based on the difference between the set flow rate and the flow rate fed back by the sonic nozzle standard flow meter, achieving rapid flow stabilization. A dynamic error compensation module compensates for the instantaneous flow rates of both the sonic nozzle standard flow meter and the ultrasonic gas meter based on the collected pressure and temperature values, converting the flow rate to standard condition flow rate before error calculation. An intelligent diagnostic module performs real-time analysis based on the collected flow data, determining whether there is excessive flow, reverse flow, or overload flow, and issues timely alerts.

[0062] In summary, this invention constructs an intelligent flow standard device system by adding high-precision temperature and pressure sensors, an intelligent flow control system, a dynamic error compensation module, and an intelligent diagnostic module to the traditional sonic nozzle standard flow device. The high-precision sensor monitors the temperature and pressure data of both the sonic nozzle standard flow device and the ultrasonic gas meter. The dynamic error compensation module compensates for the instantaneous flow rates of both the sonic nozzle standard flow device and the ultrasonic gas meter based on the collected pressure and temperature values, converting the flow rate to standard condition flow rate before error calculation, thus reducing errors caused by the influence of temperature and pressure on the instantaneous flow rate. The intelligent diagnostic module performs real-time analysis based on the collected flow data, identifying and promptly issuing alerts for corrections such as low flow rates, reverse flow rates, and overload flow rates, improving calibration efficiency. The intelligent flow standard device system synchronizes the time of the ultrasonic gas meter and the sonic nozzle standard flow device, then collects the instantaneous flow rates of both devices at the same time, avoiding errors introduced by asynchronous acquisition times or response delays that result in inconsistent instantaneous flow rates.

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An ultrasonic gas meter verification method based on the instantaneous flow method, characterized in that, include: Time synchronization between the flow standard device and the ultrasonic gas meter; Adjust the flow rate to the flow point to be detected according to the control command; The instantaneous flow rate, temperature, and pressure values ​​of the flow rate standard device under the same operating conditions are obtained at the same time. Based on the instantaneous flow value of the flow standard device, the flow point to be detected is judged to determine whether there is abnormal flow. If so, an alarm signal is issued. The instantaneous flow rate of the flow standard device under standard conditions is obtained by dynamic compensation based on the instantaneous flow rate value, temperature value, and pressure value of the flow standard device under standard conditions. The instantaneous flow rate of the ultrasonic gas meter under standard conditions is obtained from the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter under operating conditions. The indication error of the ultrasonic gas meter under standard conditions is obtained based on the instantaneous flow value of the flow standard device under standard conditions and the instantaneous flow value of the ultrasonic gas meter under standard conditions.

2. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 1, characterized in that, The step of determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: If the instantaneous flow rate value of the flow rate standard device is less than the minimum value of the flow rate point to be detected, and the instantaneous flow rate value of the flow rate standard device is greater than 0, then there is a small flow rate.

3. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 1, characterized in that, The step of determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: If the instantaneous flow rate value of the flow rate standard device is greater than the maximum value of the flow rate point to be detected, then there is an overload flow rate.

4. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 1, characterized in that, The step of determining whether there is abnormal flow based on the instantaneous flow value of the flow standard device and the flow point to be detected includes: If the instantaneous flow rate value of the flow rate standard device is less than 0, then there is reverse flow.

5. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 1, characterized in that, The formula for calculating the instantaneous flow rate of the flow standard device under standard conditions by dynamically compensating for the instantaneous flow rate, temperature, and pressure values ​​of the flow standard device under operating conditions is as follows: In the formula, This refers to the instantaneous flow rate value of the flow standard device under standard conditions; The instantaneous flow rate value of the flow standard device under operating conditions; The temperature value of the flow rate standard device under operating conditions; The pressure value of the flow rate standard device under operating conditions; The temperature value of the flow rate standard device under standard conditions; The pressure value of the flow standard device under operating conditions.

6. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 5, characterized in that, The formula for calculating the instantaneous flow rate of the ultrasonic gas meter under standard conditions, based on the instantaneous flow rate, temperature, and pressure values ​​of the ultrasonic gas meter under operating conditions, is as follows: In the formula, This represents the instantaneous flow rate of the ultrasonic gas meter under standard conditions. This represents the instantaneous flow rate of the ultrasonic gas meter under operating conditions. The temperature value of the ultrasonic gas meter under operating conditions; This represents the pressure value of the ultrasonic gas meter under operating conditions.

7. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 6, characterized in that, The formula for calculating the indication error of the ultrasonic gas meter under standard conditions, based on the instantaneous flow value of the flow standard device under standard conditions and the instantaneous flow value of the ultrasonic gas meter under standard conditions, is as follows: In the formula, is the indication error of the ultrasonic gas meter at standard conditions.

8. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 7, characterized in that, The formula for calculating the instantaneous flow rate of the ultrasonic gas meter under the aforementioned operating conditions is as follows: wherein is the cross-sectional area of the gas flow; is the velocity of the gas flow.

9. The ultrasonic gas meter calibration method based on instantaneous flow rate method according to claim 8, characterized in that, The formula for calculating the velocity of the gas flow is: wherein is the length of the flow path for the ultrasonic wave propagation; is the angle between the direction of the gas flow and the direction of the transducer; is the first propagation time; is the second propagation time.

10. The ultrasonic gas meter calibration method based on the instantaneous flow rate method according to claim 9, characterized in that, The formula for calculating the first propagation time is: The formula for calculating the second propagation time is: wherein is the speed of sound.

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