Method for measuring propagation time of ultrasonic waves in gas

Abstract

The invention discloses a method for measuring the propagation time of ultrasonic waves in gas, and belongs to the technical field of ultrasonic gas metering. The method comprises the following steps: establishing a propagation time calculation model based on a measurement resolution error and a time delay error; the sound velocity and the measurement propagation time of the ultrasonic wave at the zero flow velocity are collected, and the measurement resolution error is calculated and determined through a least square method; the countercurrent measurement propagation time and the downstream measurement propagation time of the ultrasonic waves at the zero flow velocity are collected, and the time delay error is calculated and determined through an averaging method; and on the basis of the determined measurement resolution error, the determined time delay error and the propagation time calculation model, performing calculation to obtain the real countercurrent propagation time and the real downstream propagation time of the ultrasonic waves. According to the method, the real countercurrent propagation time and the real downstream propagation time of the ultrasonic waves can be accurately calculated, and the accuracy of measuring the propagation time of the ultrasonic waves in the gas medium is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic gas metering, and in particular to a method for measuring the propagation time of ultrasonic waves in gas. Background Art

[0002] The core principle of ultrasonic gas metering is to utilize the propagation time difference of ultrasonic signals in the gas flow. Generally speaking, the propagation speed of ultrasonic signals is affected by the flow direction of the fluid. When gas flows, ultrasonic waves propagate faster in the downstream direction and slower in the upstream direction. Therefore, the propagation time difference of ultrasonic waves can be used to estimate the flow velocity and, further, calculate the gas flow rate.

[0003] However, related technologies often ignore the fixed errors caused by many factors such as measurement resolution, sensor installation asymmetry, and measurement circuit asymmetry in the measurement of ultrasonic propagation time. This ultimately leads to inaccurate measurement of ultrasonic propagation time in gas, which in turn affects the accuracy of gas flow calculation. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for measuring the propagation time of ultrasound in gas, aiming to solve the technical problem in the related art that the measurement of the propagation time of ultrasound in gas medium is not accurate enough.

[0005] To achieve the above object, the present invention provides a method for measuring the propagation time of ultrasound in gas, the method comprising the following steps:

[0006] S1, establishes a propagation time calculation model based on the measurement resolution error and time delay error;

[0007] S2, collecting the sound velocity and measuring the propagation time of the ultrasonic wave at zero flow rate, and determining the measurement resolution error by least squares calculation;

[0008] S3, collecting the upstream measurement propagation time and the downstream measurement propagation time of the ultrasonic wave at zero flow rate, and calculating and determining the time delay error by using the mean method;

[0009] S4, calculating the true upstream propagation time and the true downstream propagation time of the ultrasonic wave based on the determined measurement resolution error, the determined time delay error and the propagation time calculation model.

[0010] This invention incorporates measurement resolution error and time delay error into the error range of ultrasonic propagation time measurement, constructing a propagation time calculation model and laying an important foundation for the subsequent accurate calculation of propagation time. On this basis, the measurement resolution error and time delay error are solved using the least squares method and the mean value method, respectively, to more accurately calculate their specific values. Combined with the propagation time calculation model, the true upstream and downstream propagation times of ultrasonic waves can be accurately calculated, greatly improving the accuracy of ultrasonic propagation time measurements in gaseous media. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of a flow chart of an embodiment of a method for measuring the propagation time of ultrasound in gas according to the present invention;

[0012] Figure 2 This is a structural diagram of ultrasonic gas metering equipment.

[0013] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0014] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0015] The inventive concept of the present application is further described below with reference to some specific embodiments and implementation methods.

[0016] The embodiment of the present invention provides a method for measuring the propagation time of ultrasonic waves in gas, referring to Figure 1 , Figure 1 The figure is a flow chart of an embodiment of a method for measuring the propagation time of ultrasound in gas according to the present invention.

[0017] In this embodiment, the method for measuring the propagation time of ultrasonic waves in gas specifically includes the following steps:

[0018] Step S1: Establishing a propagation time calculation model based on the measurement resolution error and time delay error.

[0019] The fixed error caused by the measurement resolution is recorded as the measurement resolution error Δt0, and the fixed error of time delay caused by the asymmetric installation of the ultrasonic sensor and the asymmetric measurement circuit is recorded as the time delay error Δt1. Based on the measurement resolution error and time delay error, the propagation time calculation model is established:

[0020] t′ up =t up +△t0+△t1

[0021] t′down =t down +△t0-△t1;

[0022] Where t′ up Indicates the propagation time of ultrasonic wave in countercurrent measurement; t′ down represents the downstream measurement propagation time of the ultrasonic wave; t up Indicates the real propagation time of ultrasonic wave in reverse flow; t down Indicates the true downstream propagation time of ultrasonic waves.

[0023] In step S1, a calculation model for the propagation time of ultrasound in the air medium is established based on the measurement resolution error and time delay error, which can accurately reflect the relationship between the true propagation time of ultrasound and the measured propagation time, thereby facilitating the subsequent accurate calculation of the true propagation time of ultrasound.

[0024] Step S2: collecting the sound velocity and measuring the propagation time of the ultrasonic wave at zero flow rate, and determining the measurement resolution error by least squares calculation.

[0025] The step S2 specifically includes the following steps:

[0026] Step S21: The arithmetic mean of the upstream measured propagation time and the downstream measured propagation time of the ultrasonic wave is taken as the measured propagation time at zero flow rate:

[0027]

[0028] Where t′ uo0 Indicates the propagation time of ultrasonic wave in countercurrent measurement at zero flow rate; t′ down0 It represents the downstream measurement propagation time of ultrasonic wave at zero flow rate; t up0 Indicates the true propagation time of ultrasonic wave in countercurrent at zero flow rate; t down0 represents the true downstream propagation time of the ultrasonic wave at zero flow velocity; t0′ represents the measured propagation time at zero flow velocity; t0 represents the true propagation time at zero flow velocity, and satisfies t0=t up0 =t down0 .

[0029] Step S22: Based on the measured propagation time at zero flow velocity, a relationship model between the actual propagation time at zero flow velocity and the speed of sound is constructed.

[0030] Specifically, if Figure 2As shown, the ultrasonic gas metering device includes ultrasonic sensor A and ultrasonic sensor B. Ultrasonic sensor A and ultrasonic sensor B are respectively arranged on the inner walls of the gas pipeline on both sides of the opposite side, and the sound wave path between ultrasonic sensor A and ultrasonic sensor B is fixed at an angle with the pipeline axis. The downstream and upstream propagation times of the ultrasonic wave satisfy the relationship 1:

[0031]

[0032] Among them, t down Indicates the downstream propagation time of ultrasonic waves in the gas (the time it takes for ultrasonic waves to propagate from sensor A to sensor B); t up It represents the countercurrent propagation time of ultrasonic wave in gas (the time for ultrasonic wave to propagate from sensor B to sensor A); L represents the designed sound channel length, that is, the sound wave path length; C f represents the speed of sound, that is, the speed at which sound waves propagate in the gas; v m It represents the average axial velocity of the gas; φ represents the sound channel angle, which is the fixed angle between the sound wave path and the central axis of the pipe.

[0033] When the gas flow rate v m = 0, taking the error of vocal tract length into consideration, the second relation can be obtained according to the first relation:

[0034]

[0035] Where k represents the difference coefficient between the actual sound channel length and the designed sound channel length; kL represents the actual sound channel length.

[0036] According to the measured propagation time at zero flow rate and equation 2, a relationship model between the true propagation time and the speed of sound at zero flow rate is constructed:

[0037]

[0038] Step S23: collecting the sound velocity and true propagation time of the ultrasonic wave at zero flow rate, and performing least squares calculation based on the relationship model between the true propagation time and the sound velocity to obtain the measurement resolution error.

[0039] The step S23 specifically includes the following steps:

[0040] Step S23-1: Transform the relationship model between the real propagation time and the speed of sound to obtain the third relationship:

[0041]

[0042] Step S23-2: Collect the sound velocity and true propagation time of the ultrasonic wave at zero flow rate.

[0043] Specifically, the gas pipeline and ultrasonic measuring instrument are installed in series and placed in a high and low temperature chamber to collect the ultrasonic propagation time. At the same time, air or gas is introduced into the pipeline and the gas flow is prohibited. An accurate sound velocity meter is used as a standard device to collect the ultrasonic sound velocity. The temperature of the high and low temperature chamber is continuously adjusted to collect the ultrasonic sound velocity C under different gases and different temperatures. fi (i=1,2,…n,n is the number of measurements) and the true propagation time t 0i (i=1, 2, ...n, n is the number of measurements).

[0044] Step S23 - 3 : Based on Relationship 3, the speed of sound of the ultrasonic wave at zero flow rate and the true propagation time, a least squares method is performed to obtain the measurement resolution error.

[0045] In the entire step S2, by establishing a relationship model between the ultrasonic sound velocity and the true propagation time under zero flow rate conditions and using the least squares method for analysis and calculation, the specific value of the measurement resolution error in the relationship model can be determined more accurately, thereby laying the foundation for the subsequent accurate calculation of the true propagation time.

[0046] Step S3: collecting the upstream measured propagation time and the downstream measured propagation time of the ultrasonic wave at zero flow rate, and calculating and determining the time delay error by using the mean value method.

[0047] The step S3 specifically includes the following steps:

[0048] Step S31: Based on the propagation time calculation model, obtain the fourth relationship:

[0049]

[0050] Step S32: collecting the upstream measurement propagation time of the ultrasonic wave and the downstream measurement propagation time of the ultrasonic wave at zero flow rate.

[0051] Specifically, the gas pipeline and ultrasonic measuring instrument are installed in series and placed in a high and low temperature box. Air or gas is introduced into the pipeline and the gas flow is prohibited. The temperature of the high and low temperature box is continuously adjusted to collect the ultrasonic counterflow measurement propagation time t' under different gases and different temperatures. up0，i (i=1, 2, ...n, n is the number of measurements) and the downstream measurement propagation time t′ of the ultrasonic wave down0，i (i=1, 2, ...n, n is the number of measurements).

[0052] Step S33: Based on the relational expression 4, the upstream measurement propagation time of the ultrasonic wave and the downstream measurement propagation time of the ultrasonic wave at zero flow rate, the time delay error Δt1 is calculated by using the mean value method.

[0053] In the entire step S3, the relationship between the time delay error and the measured propagation time is obtained based on the propagation time calculation model analysis in step S1. On this basis, the upstream measured propagation time and the downstream measured propagation time under zero flow rate are collected, and the mean method is used for calculation. Then, the time delay error can be determined more accurately, which further lays the foundation for the subsequent accurate calculation of the true propagation time.

[0054] Step S4: Based on the determined measurement resolution error, the determined time delay error and the propagation time calculation model, the upstream true propagation time and the downstream true propagation time of the ultrasonic wave are calculated.

[0055] Specifically, the propagation time calculation model is deformed to obtain the relationship 5:

[0056] t up =t′ up -△t0-△t1

[0057] t down =t′ down -△t0+△t1.

[0058] Substituting the measured upstream and downstream propagation times into equation 5, since the measurement resolution error and time delay error are both determined, the true upstream and downstream propagation times can be calculated.

[0059] In this embodiment, by incorporating measurement resolution error and time delay error into the error range of ultrasonic propagation time measurement, a propagation time calculation model is constructed, laying an important foundation for the subsequent accurate calculation of propagation time. On this basis, the measurement resolution error and time delay error are solved using the least squares method and the mean value method, respectively, to more accurately calculate their specific values. Combined with the propagation time calculation model, the true upstream and downstream propagation times of ultrasonic waves can be accurately calculated, significantly improving the accuracy of ultrasonic propagation time measurements in gaseous media.

[0060] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0061] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for measuring the propagation time of ultrasound in gas, characterized in that: The method comprises the following steps: S1, establishes a propagation time calculation model based on the measurement resolution error and time delay error; S2, collecting the sound velocity and measuring the propagation time of the ultrasonic wave at zero flow rate, and determining the measurement resolution error by least squares calculation; S3, collecting the upstream measurement propagation time and the downstream measurement propagation time of the ultrasonic wave at zero flow rate, and calculating and determining the time delay error by using the mean method; S4, calculating the true upstream propagation time and the true downstream propagation time of the ultrasonic wave based on the determined measurement resolution error, the determined time delay error and the propagation time calculation model.

2. The method for measuring the propagation time of ultrasonic waves in gas according to claim 1, wherein: The S2 specifically includes: S21, taking the arithmetic mean of the ultrasonic wave's upstream measured propagation time and downstream measured propagation time as the measured propagation time at zero flow rate: Where t′ up0 Indicates the propagation time of ultrasonic wave in countercurrent measurement at zero flow rate; t′ down0 It represents the downstream measurement propagation time of ultrasonic wave at zero flow rate; t up0 Indicates the true propagation time of ultrasonic wave in countercurrent at zero flow rate; t down0 represents the true downstream propagation time of the ultrasonic wave at zero flow velocity; t′0 represents the measured propagation time at zero flow velocity; t0 represents the true propagation time at zero flow velocity, and satisfies t0=t up0 =t down0 ; S22, constructing a relationship model between the true propagation time and the sound speed at zero flow rate based on the measured propagation time at zero flow rate; S23, collecting the sound velocity and true propagation time of the ultrasonic wave at zero flow rate, and performing least squares calculation based on a relationship model between the true propagation time and the sound velocity to obtain the measurement resolution error.

3. The method for measuring the propagation time of ultrasonic waves in gas according to claim 2, wherein: The S23 specifically includes: S23-1: Transform the relationship model between the real propagation time and the speed of sound to obtain the third relationship: S23-2, collecting the sound velocity and true propagation time of the ultrasonic wave at zero flow rate; S23-3, based on Relationship 3, the speed of sound of the ultrasonic wave at zero flow rate and the true propagation time, perform least squares calculation to obtain the measurement resolution error.

4. The method for measuring the propagation time of ultrasonic waves in gas according to claim 2, wherein: The S3 specifically includes: S31, based on the propagation time calculation model, obtain the fourth relationship: S32, collecting the upstream measurement propagation time of the ultrasonic wave and the downstream measurement propagation time of the ultrasonic wave at zero flow rate; S33, based on the relational expression 4, the ultrasonic wave's upstream measurement propagation time and the ultrasonic wave's downstream measurement propagation time at zero flow rate, the time delay error Δt1 is calculated using the mean value method.

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