A temperature-adaptive ultrasonic flow measurement method and system

Abstract

The present invention belongs to the field of flow detection technology, and specifically relates to a temperature-adaptive ultrasonic flow measurement method and system, wherein the method includes S101, using a first probe and a second probe to send a first transmission signal and a second transmission signal, respectively, and correspondingly collecting a first reception signal and a second reception signal; S102, selecting two modes from the multiple modes; S103, respectively obtaining the forward and reverse flow times under the first mode and the second mode; S104, calculating the volume flow rate based on the forward and reverse flow times in S103; through the above method, the present application comprehensively provides a temperature-adaptive ultrasonic flow measurement method that can be applied to large-diameter and large-flow pipelines, reducing the cumbersome temperature compensation process in the prior art.

Description

[0001] Priority application

[0002] This application claims priority to Chinese invention patent application [2024118796673] "[A temperature-adaptive ultrasonic flow measurement method and system]" filed on December 19, 2024, which is incorporated by reference in its entirety. Technical Field

[0003] The present invention belongs to the technical field of flow detection, and in particular relates to a temperature-adaptive ultrasonic flow measurement method and system. Background Art

[0004] Ultrasonic flowmeters measure flow by detecting the effect of fluid flow on an ultrasonic beam (or ultrasonic pulse). Ultrasonic flowmeters use various flow measurement principles, including time difference, beam deviation, and Doppler flow measurement.

[0005] Temperature is a significant factor affecting the accuracy of transit-time ultrasonic flowmeters. On the one hand, the speed at which ultrasonic waves propagate in the medium (the velocity of sound) varies with temperature; on the other hand, ultrasonic pipe sections expand and contract with temperature changes, altering the propagation path of the ultrasonic waves. To eliminate the effects of temperature on measurement accuracy, various methods have been proposed, such as installing temperature sensors and then correcting flow results based on the measured temperature and actual operating conditions.

[0006] Among them, the Chinese invention patent with announcement number CN101464171B discloses an ultrasonic flow detection system and detection method, which particularly relates to a high-precision ultrasonic fluid flow detection system and detection method. The method adopts an improved time difference method to calculate the fluid velocity; adopts delayed window receiving technology to reduce the impact of noise in the detection on the detection accuracy through pulse width detection; and adopts interpolation correlation method and correlation coefficient judgment method to further improve the resolution of the system measurement time to 1.25ns, thereby significantly improving the precision and accuracy of the ultrasonic flowmeter.

[0007] However, this solution has high requirements on the stability of the fluid flow process, so it is greatly limited in application scenarios. Summary of the Invention

[0008] The object of the present invention is to provide a temperature-adaptive ultrasonic flow measurement method and system to partially alleviate or solve the above-mentioned shortcomings and improve the flow measurement accuracy in large-diameter and large-flow scenarios.

[0009] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions:

[0010] A first aspect of the present invention is to provide a temperature-adaptive ultrasonic flow measurement method, comprising the steps of:

[0011] S101, using a first probe and a second probe to send a first transmit signal and a second transmit signal, respectively, and correspondingly collecting a first receive signal and a second receive signal; wherein the first transmit signal or the second transmit signal generates multiple modes during propagation in a system to be measured, and the first receive signal or the second receive signal includes receive signals in the multiple modes;

[0012] S102, selecting two modes from the multiple modes, and defining the two selected modes as a first mode and a second mode respectively;

[0013] S103, acquiring, according to the received signal, a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode;

[0014] S104: Calculate the volume flow rate using the following model based on the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time:

[0015] ;

[0016]

[0017] ;

[0018] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius of the system to be measured.

[0019] As an improvement, in S102, the specific steps of selecting the two modes include:

[0020] S1021, determining whether the current mode satisfies a selection condition, wherein the selection condition requires that the amplitude of the received signal in the current mode is greater than a first preset amplitude threshold, and / or the signal length of the received signal in the current mode is within a first preset length threshold range; if so, classifying the mode into the selectable mode set;

[0021] S1023: Select two modalities from the optional modality set, and define the two modalities as a first modality and a second modality, respectively.

[0022] As an improvement, before S1023, the following steps are further included:

[0023] S1022: Determine whether the number of modes in the optional mode set is greater than or equal to two. If so, execute S1023; otherwise, adjust the first preset amplitude threshold according to the first decrement until the number of modes satisfies the requirement of being greater than or equal to two.

[0024] As an improvement, in step S1023, the specific steps of selecting two modes from the optional mode set include: when the number of modes is greater than two, selecting the mode with the largest amplitude of the received signal as the first mode, and selecting the mode with the amplitude of the received signal closest to the first amplitude of the first mode as the second mode.

[0025] As an improvement, the following steps are also included:

[0026] S105 , correcting the volume flow obtained in S104 using a preset correction rule, wherein the correction rule is to multiply the volume flow by a pre-obtained calibration coefficient.

[0027] Another aspect of the present invention is to provide a temperature-adaptive ultrasonic flow measurement system, comprising:

[0028] A first acquisition module is configured to transmit a first transmission signal and a second transmission signal using a first probe and a second probe, respectively, and to acquire a first reception signal and a second reception signal accordingly; wherein the first transmission signal or the second transmission signal generates multiple modes during propagation in the system to be measured, and the first reception signal or the second reception signal includes reception signals under the multiple modes;

[0029] A first mode selection module is configured to select two modes from the multiple modes and define the two modes as a first mode and a second mode respectively;

[0030] a time acquisition module configured to respectively acquire, through the received signal, a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode;

[0031] A first calculation module is configured to calculate a volume flow rate using the following model according to the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time;

[0032] ;

[0033]

[0034] ;

[0035] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius of the system to be measured.

[0036] As an improvement, the first modality selection module is specifically configured as follows:

[0037] Determine whether the current mode meets a selection condition, where the selection condition requires that the amplitude of the received signal under the current mode is greater than a first preset amplitude threshold, and / or the signal length of the received signal under the current mode is within a first preset length threshold range; if so, classify the mode into an optional mode set; select two modes from the optional mode set, and define the two modes as a first mode and a second mode, respectively.

[0038] As an improvement, it also includes:

[0039] A modality quantity determination module is configured to determine whether the number of modalities in the optional modality set is greater than or equal to two.

[0040] An adjustment module is configured to adjust the first preset amplitude threshold according to a first decrement when the number of modes in the optional mode set is less than two, until the number of modes satisfies a condition of being greater than or equal to two.

[0041] As an improvement, the first mode selection module is specifically configured to: when the number of modes is greater than two, select the mode with the largest amplitude of the received signal as the first mode, and select the mode with the amplitude of the received signal closest to the first amplitude of the first mode as the second mode.

[0042] As an improvement, it also includes:

[0043] The first flow correction module is configured to correct the volume flow calculated by the first calculation module using a preset correction rule, wherein the correction rule is to multiply the volume flow by a pre-obtained calibration coefficient.

[0044] The principles and beneficial technical effects of the present invention are:

[0045] In large-diameter pipes, due to the high flow rate and the large kinetic energy of the fluid, the fluctuation amplitude of the fluid flow increases. When the flow rate increases, the disturbance of the fluid to the ultrasonic wave will also increase, which will cause a large error in the measurement of the propagation time of the ultrasonic signal. This error will be amplified in the subsequent calculation process, so the error of the volume flow calculated based on time will also increase significantly.

[0046] For the above-mentioned large-diameter and high-flow-rate scenarios, this application compensates for the above-mentioned errors based on the ultrasonic transmission time difference between finite modes (dual modes). By measuring the upstream and downstream time differences between two different modes (which include the upstream and downstream time difference of the first mode, the upstream and downstream time difference under the second mode, and the multi-dimensional time difference of the cross-stream and downstream time difference under the first mode and the second mode), and using the multi-dimensional time difference information to compensate for the measurement error under a single mode, a more accurate temperature-adaptive flow measurement method is comprehensively provided, which is particularly suitable for the measurement of large-diameter flow.

[0047] Specifically, in the mode selection process, the present application provides a high-intensity dual-modal data acquisition mechanism, which imposes dual restrictions on amplitude and signal length, and selects the two most representative modes. On the one hand, the mode with a larger amplitude can retain the integrity of the original signal to the greatest extent and reduce the interference of other factors (such as noise); on the other hand, the signal length is restricted, and the mode of the received signal with a larger signal length is selected within the preset length threshold range. A wider data acquisition window can be divided under this mode, thereby obtaining more data point information, and then using multiple data point information as original data to calculate more accurate upstream and downstream time, thereby improving the accuracy of flow measurement without excessively increasing the amount of data acquisition and processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the embodiments or the description of the prior art. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the various elements or parts are not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without inventive work.

[0049] Figure 1 Schematic diagram of the flow meter measurement principle in an embodiment of the present invention;

[0050] Figure 2 Schematic diagram of ultrasonic flowmeter signal characteristics in an embodiment of the present invention;

[0051] Figure 3 Flowchart of a temperature-adaptive ultrasonic flow measurement method according to an embodiment of the present invention;

[0052] Figure 4 A modular schematic diagram of a temperature-adaptive ultrasonic flow measurement system according to an embodiment of the present invention;

[0053] Figure 5 Flowchart of a multi-modal ultrasonic flow fusion method according to an embodiment of the present invention;

[0054] Figure 6 Schematic diagram of the modularization of a multi-modal ultrasonic flow fusion system according to an embodiment of the present invention;

[0055] Figure 7 Schematic diagram of the amplitude of the acoustic wave in the forward and reverse flow in the first mode of simulation experiment 1;

[0056] Figure 8 Schematic diagram of the amplitude of the acoustic wave in the forward and reverse flow in the second mode of simulation experiment 1;

[0057] Figure 9 This is a comparison chart of flow rate change in simulation experiment 1;

[0058] Figure 10 Schematic diagram of the amplitude of the acoustic wave under the first mode of the simulation experiment 2;

[0059] Figure 11 Schematic diagram of the amplitude of the acoustic wave under the second mode of the simulation experiment 2;

[0060] Figure 12 This is a comparison chart of flow rate change in simulation experiment 2. DETAILED DESCRIPTION

[0061] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] Herein, the use of suffixes such as "module", "component" or "unit" to indicate elements is only for the purpose of facilitating the description of the present invention and has no specific meaning in itself. Therefore, "module", "component" or "unit" can be used interchangeably. Herein, the orientation or positional relationship indicated by the terms "upper", "lower", "inside", "outside", "front", "back", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0063] As used herein, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood broadly. For example, "connected" can mean fixed, removable, or integral; it can mean mechanical, direct, or indirect through an intermediary, or it can mean internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention. As used herein, "plurality" means two or more, including two, three, four, five, etc.

[0064] The ultrasonic measurement principle in the prior art is as follows Figure 1 As shown, the piezoelectric ceramic in the ultrasonic probe (mainly including a piezoelectric ceramic sheet and an acoustic wedge) is connected to the pipe wall through the acoustic wedge, and the sound wave propagation path can be extended by changing the position of the acoustic wedge.

[0065] The angle between the normal direction of the piezoelectric ceramic sheet and the normal direction of the pipe wall is , the pipe wall thickness is , the distance between the acoustic wedges is , the piezoelectric ceramic piece is on the plane of the pipe axis. The measured pipe radius is Considering that the pipe wall and the ultrasonic wedge are made of the same material, the ultrasonic wave propagates at the same speed in the wedge and the pipe wall, and the angle does not change. On the inner wall of the pipe, due to the inconsistent propagation speed of the sound wave in different media, the refraction angle The propagation speeds of sound waves in the pipe wall and fluid are and , then the refraction angle satisfies Snell's law, that is:

[0066] (1)

[0067] The electrical signal generates an ultrasonic mechanical signal by stimulating the piezoelectric ceramic 1. The ultrasonic signal is refracted at the pipe wall and enters the propellant. It propagates along the flow direction and reaches the piezoelectric ceramic 2, causing the piezoelectric ceramic to generate a piezoelectric signal to form an electrical signal. The propagation time difference between the two signals is recorded as the downstream time. On the other hand, when the electric signal excites the piezoelectric ceramic 2 to generate ultrasonic waves, the propagation direction is opposite to the flow direction, forming a counter-flow time. .

[0068] In pipeline flow, the flow field formed by fluid flow is relatively complex. For the convenience of modeling, it is assumed that the fluid flow field is a uniform flow field ( ). Without considering the propagation time of the sound wave in the sound wedge and the pipe wall, Figure 1 The corresponding upstream and downstream propagation time is

[0069] (2)

[0070] Then there is

[0071] (3)

[0072] at the same time

[0073] (4)

[0074] Substituting formula (4) into formula (3) yields

[0075] (5)

[0076] The volume flow rate can be expressed as

[0077] (6)

[0078] Similarly, substituting formula (5) into formula (4) can obtain the speed of sound

[0079] (7)

[0080] Furthermore, from formula (1), we can get: is related to the propagation speed of sound waves in the fluid, then formula (1) can be substituted into the above formula to obtain

[0081] (8)

[0082] In the above formula, Represents the speed of sound waves in solids. When the speed of sound in a fluid is known and the fluid pressure does not change much, there is a corresponding relationship between the speed of sound and the temperature. From this, the fluid temperature and, hence, the fluid density, can be determined.

[0083] Furthermore, the volume flow rate can be expressed as

[0084] (9)

[0085] It is not difficult to see that and The pipe radius is fixed during the design phase and will not change. Affected by temperature, temperature compensation experiments need to be carried out to compensate.

[0086] When using a continuous wave, assuming the frequency of the sound wave signal is , then time ( ) and phase ( ) There is the following formula

[0087] (10)

[0088] Substituting the above formula into formula (8) we can get the speed of sound in the fluid as

[0089] (11)

[0090] in, is the countercurrent phase, It is the downstream phase;

[0091] Substituting the above formula into formula (9) we can get the volume flow formula

[0092] (12)

[0093] It can be seen from the formula that whether it is time-based volume measurement (Formula (9)) or phase-based volume measurement (Formula (12)), there is a sound wave propagation speed Given as a parameter. This parameter changes with temperature.

[0094] Example 1

[0095] In order to eliminate the influence of temperature on volume flow measurement, the present invention provides a temperature-adaptive ultrasonic flow measurement method, see Figure 3 , including the following steps:

[0096] S101, using a first probe and a second probe to send a first transmit signal and a second transmit signal, respectively, and correspondingly collecting a first receive signal and a second receive signal; wherein the first transmit signal or the second transmit signal generates multiple modes during propagation in a system to be measured, and the first receive signal or the second receive signal includes receive signals in the multiple modes;

[0097] S102, selecting two modes from the multiple modes, and defining the two selected modes as a first mode and a second mode respectively;

[0098] S103, respectively acquiring a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode through the received signal;

[0099] S104: Calculate the volume flow rate using the following model based on the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time:

[0100] ;

[0101]

[0102] ;

[0103] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius of the system to be measured.

[0104] Among them, when When , it means the fluid in the pipe is flowing in the forward direction.

[0105]

[0106] when When , it means the fluid in the pipe is flowing in the reverse direction.

[0107]

[0108] Among them, the device used to obtain modal information in S101 can refer to the inventor's prior patent (CN115493662B, integrated ultrasonic flowmeter and system for aerospace); the acquisition of relevant parameters of multiple modes can refer to the patent (CN119023015A, multi-modal ultrasonic fluid multi-parameter measurement device and method).

[0109] In some embodiments, in S102, the specific steps of selecting the modality include:

[0110] S1021: Determine whether the current mode satisfies a selection condition, wherein the selection condition requires that the amplitude of the received signal in the current mode is greater than a first preset amplitude threshold, and / or the signal length of the received signal in the current mode is within a first preset length threshold range. If so, the mode is included in the selectable mode set. Specifically, determine whether the amplitude of the received signal in the current mode is greater than the first preset amplitude threshold, and / or determine whether the signal length of the received signal in the current mode is within a first preset length threshold range. If at least one of the above conditions is met (including the following three situations: 1. the amplitude of the received signal in the current mode is greater than the first preset amplitude threshold, but the signal length of the received signal in the current mode is not within the first preset length threshold range; 2. the amplitude of the received signal in the current mode is less than the first preset amplitude threshold, but the signal length of the received signal in the current mode is within the first preset length threshold range; 3. the amplitude of the received signal in the current mode is greater than the first preset amplitude threshold, and the signal length of the received signal in the current mode is within the first preset length threshold range), the mode is included in the selectable mode set.

[0111] S1023: Select two modalities from the optional modality set, and define the two modalities as a first modality and a second modality, respectively.

[0112] This application provides a high-intensity, wide-range modal data acquisition mechanism to improve the accuracy of flow measurement directly from the data source.

[0113] Among them, see Figure 2 , amplitude refers to the strength of the received signal corresponding to each mode. The greater the strength of the received signal, the greater its amplitude. Signal length refers to the width of the corresponding received signal under each mode. For example, the signal length corresponding to mode 3 is X. In this application, the number of cycles of the excitation signal is limited to about 60, and the number of sampling points within the corresponding signal length range is 1024. By limiting the number of cycles of the excitation signal, the data collection volume is guaranteed without excessively increasing the difficulty of data processing, and avoiding the problem that the excitation signal is too large, resulting in an excessively long acquisition signal, and then the excessively long acquisition signal length will lead to an increase in data collection and processing volume.

[0114] The signal length refers to the actual time span from the beginning to the end of the signal, usually in seconds (s); the number of sampling points refers to the number of samples of the signal at discrete time points.

[0115] This application imposes dual restrictions on the amplitude and signal length of the mode, selects key modes for calculation, and can directly improve the accuracy of flow measurement from the data source. Specifically, modes with larger amplitudes are usually less subject to interference during transmission and will be more accurate; and when the signal length of the received signal is large, a wider data acquisition window can be divided under this mode to obtain more data point information (that is, sampling point data selected from the received signal, the data may include the time and / or amplitude of the acquisition), and then the multiple data point information is used as the original data to calculate the more accurate upstream and downstream time using the Fourier transform method. Among them, the specific steps of calculating the upstream and downstream time using the Fourier transform method can be found in the steps of calculating the downstream delay time (equivalent to the downstream propagation time in this article) and the downstream delay time (equivalent to the upstream propagation time in this article) in the Chinese invention patent with announcement number CN119023014A.

[0116] In some embodiments, S1021 also includes determining whether the duration of the current excitation signal is greater than a first preset time threshold; when the duration of the excitation signal is longer, a sufficient number of modes can usually be generated, and selecting key modes from these modes for data collection is more representative and the measured data is more accurate.

[0117] In some embodiments, S1021 further includes determining whether the amplitude of the received signal in the current mode is less than a second preset amplitude threshold; if so, classifying the mode into the optional mode set.

[0118] See also Figure 2, different amplitudes and durations are collected correspondingly under different modes; in this article, the first preset amplitude threshold can be a specific amplitude determined by the user based on the amplitudes of multiple modes under different experimental conditions obtained based on preliminary experiments, but at the same time, the amplitude should be lower than the safe amplitude value (if the sound wave amplitude is too large, it may cause damage to the equipment. Therefore, the safe amplitude value refers to the maximum amplitude value that will not cause damage to the equipment; accordingly, the second preset amplitude threshold can be an amplitude value between the first preset amplitude threshold and the safe amplitude value); accordingly, the first preset length threshold range can be a specific signal length threshold range determined by the user based on the signal lengths of multiple modes under different experimental conditions obtained based on preliminary experiments. The signal length within this range can ensure that the received signal of the modality can be collected as much as possible without collecting too many invalid signals; the first preset time threshold can be a specific time value determined by the user based on the durations of multiple modes under different experimental conditions obtained based on preliminary experiments.

[0119] In some embodiments, before S1023, the step is also included: S1022, determining whether the number of modes in the optional mode set is greater than or equal to two, if so, executing S1023, otherwise adjusting the first preset amplitude threshold according to the first decrement until the number of modes satisfies the requirement of being greater than or equal to two.

[0120] That is to say, the first preset amplitude threshold may also be adjusted according to actual conditions to ensure that the number of modes in the optional mode set is greater than or equal to two.

[0121] In some embodiments, in step S1023, the specific steps of selecting two modes from the optional mode set include: when the number of modes is greater than two, selecting the mode with the largest amplitude of the received signal as the first mode, and selecting the mode with the amplitude of the received signal closest to the first amplitude of the first mode as the second mode.

[0122] In some embodiments, the steps further include:

[0123] S105 , correcting the volume flow obtained in S104 using a preset correction rule, wherein the correction rule is to multiply the volume flow by a pre-obtained calibration coefficient.

[0124] In some embodiments, the calibration coefficient is obtained in the following manner:

[0125] Conduct a preliminary experiment under experimental conditions to obtain the actual flow results of the current pipeline (measurement system) under experimental conditions and the mode within the calibration area and calculated flow results ; Wherein, the calibration area is an area corresponding to at least two modes among the multiple modes obtained through the preliminary experiment;

[0126] According to the actual flow results And the calculated flow results Calculate the calibration coefficient ;

[0127] ;

[0128] Among them, the calculated flow result The actual flow rate is calculated using the above steps S101-S104; It can be directly obtained by presetting the volume flow rate of the fluid injected into the pipeline.

[0129] In some embodiments, when determining the calibration coefficient, the steps further include: repeating the preliminary experiment under different experimental conditions to obtain the calibration coefficient under different experimental conditions, wherein the experimental conditions include at least the number of modes;

[0130] Correspondingly, in S105 , before correcting the volume flow, the process further includes: acquiring current conditions, matching the experimental conditions according to the current conditions, and obtaining calibration coefficients matching the current conditions.

[0131] In some embodiments, the specific steps of matching the experimental conditions according to the current conditions include:

[0132] S51, obtaining at least two sets of received signals (also referred to as amplitude signals) of at least two modes in a calibration area under current conditions, and at least two sets of standard received signals measured in at least two modes in the calibration area under experimental conditions;

[0133] S52, respectively calculating amplitude differences between the at least two groups of received signals and the at least two groups of standard received signals to obtain at least two amplitude differences;

[0134] S53, determining whether at least two of the amplitude differences are both smaller than a first preset difference; if so, matching the current condition with the experimental condition.

[0135] In some embodiments, the specific steps of matching the experimental conditions according to the current conditions include:

[0136] S54, obtaining received signals of at least two modes within the calibration area under current conditions;

[0137] S55: Determine whether the signal lengths in the received signals all meet the first preset length threshold range; if so, match the current condition with the experimental condition.

[0138] It should be noted that when matching the experimental conditions based on the current conditions, either only the amplitude or the signal length can be selected for matching, or both can be selected for matching. Furthermore, if a mismatch occurs, the amplitude and / or signal length can be remeasured for matching, or the excitation conditions can be adjusted or other methods can be used to reacquire the amplitude and / or signal length for matching.

[0139] In order to verify the reliability of this solution, the following verification experiments were conducted, among which, Verification Experiment 1 (see Figure 7-Figure 9 ) is obtained by conducting a verification experiment at an ambient temperature of -14°C and a medium temperature in the pipe of -16°C, where Figure 7 and Figure 8 Schematic diagram of the change of the amplitude of the upstream and downstream sound waves with time in the first mode (mode 1) and the second mode (mode 2). Figure 7 and Figure 8 The flow rate change diagram of the ultrasonic flowmeter is drawn by the data in the figure, and the flow rate change data directly measured by the standard mass flowmeter is introduced to obtain Figure 9 From the flow rate change comparison diagram shown, it can be seen that the flow rate measured by this solution is basically consistent with the standard data under ideal conditions measured by the mass flow meter, which also confirms the reliability of this solution.

[0140] To further verify the accuracy of this solution, the applicant also conducted the above experiment again at an ambient temperature of -13°C and a medium temperature in the tube of -15.8°C (Verification Experiment 2). Figure 10-12 It can be found that under this condition, the flow rate measured by this solution is also very close to the standard data measured by the standard mass flow meter, which further confirms the reliability of this solution.

[0141] It can be seen that the above-mentioned method of expressing volume flow does not take into account the propagation speed of sound waves, thereby achieving temperature adaptation.

[0142] In summary, the present invention compensates for the error based on the ultrasonic transmission time difference between finite modes (dual modes), and comprehensively provides a temperature-adaptive flow measurement method with higher accuracy, which is particularly suitable for measuring flow in large pipe diameters.

[0143] Furthermore, the present application provides a high-intensity, wide-amplitude modal data acquisition mechanism, which imposes dual restrictions on amplitude and signal length, and selects the two most representative modes. On the one hand, the mode with a larger amplitude can retain the integrity of the original signal to the greatest extent and reduce the interference of other factors (such as noise); on the other hand, the signal length is restricted, and the mode of the received signal with a larger signal length is selected within the preset length threshold range, which can divide a wider data acquisition window under this mode, thereby obtaining more data point information, and then using multiple data point information as original data to calculate more accurate upstream and downstream time, thereby improving the accuracy of flow measurement without excessively increasing the amount of data acquisition and processing.

[0144] Furthermore, the present invention corrects the measured flow results, which can further compensate for errors caused by differences in conditions (for example, different numbers of modes excited by ultrasonic signals with different periods), and further improve the accuracy of flow measurement; wherein, during the correction process, the corresponding calibration coefficients are respectively measured for different experimental conditions (for example, different numbers of modes), which can make it possible to match the specified calibration coefficient under the mode according to the current mode in the process of measuring volume flow, and further improve the accuracy; in addition, before matching the calibration coefficients, by performing a preliminary screening of the current conditions, for example, limiting the length and amplitude of the collected signal in the calibration area, and selecting a more reliable calibration coefficient, it can effectively avoid the problem of inaccurate received signals (modes) caused by, for example, unstable excitation signals or other accidental factors.

[0145] Example 2

[0146] See also Figure 4 The present invention provides a temperature-adaptive ultrasonic flow measurement system, comprising:

[0147] A first acquisition module is configured to transmit a first transmission signal and a second transmission signal using a first probe and a second probe, respectively, and to acquire a first reception signal and a second reception signal accordingly; wherein the first transmission signal or the second transmission signal generates multiple modes during propagation in the system to be measured, and the first reception signal or the second reception signal includes reception signals under the multiple modes;

[0148] A first mode selection module is configured to select two modes from the multiple modes, and the two modes are defined as a first mode and a second mode respectively;

[0149] A time acquisition module is configured to respectively acquire a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode through the received signal;

[0150] A first calculation module is configured to calculate the volume flow rate using the following model according to the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time:

[0151] ;

[0152]

[0153] ;

[0154] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius of the system to be measured.

[0155] Among them, when When , it means the fluid in the pipe is flowing in the forward direction.

[0156]

[0157] when When , it means the fluid in the pipe is flowing in the reverse direction.

[0158]

[0159] In some embodiments, the first modality selection module is specifically configured to determine whether the current modality meets the selection conditions, and the selection conditions require that the amplitude of the received signal under the current modality is greater than a first preset amplitude threshold, and / or the signal length of the received signal under the current modality is within a first preset length threshold range; if so, the modality is included in the optional modality set; and two modalities are selected from the optional modality set, and the two modalities are defined as the first modality and the second modality, respectively.

[0160] In some embodiments, it further includes:

[0161] A modality number determination module is configured to determine whether the number of modalities in the optional modality set is greater than or equal to two;

[0162] An adjustment module is configured to adjust the first preset amplitude threshold according to a first decrement when the number of modes in the optional mode set is less than two, until the number of modes satisfies a condition of being greater than or equal to two.

[0163] In some embodiments, the first modality selection module is specifically configured to: when the number of modes is greater than two, select the mode with the largest amplitude of the received signal as the first mode, and select the mode with the amplitude of the received signal closest to the first amplitude of the first mode as the second mode.

[0164] In some embodiments, it further includes: a first correction module: configured to correct the volume flow calculated by the first calculation module using a preset correction rule, wherein the correction rule is to multiply the volume flow by a pre-obtained calibration coefficient.

[0165] The calibration coefficient is obtained in the following way:

[0166] Conduct a preliminary experiment under experimental conditions to obtain the actual flow results of the current pipeline under experimental conditions and calculated flow results ;

[0167] According to the actual flow results And the calculated flow results Calculate the calibration coefficient ;

[0168] ;

[0169] Among them, the calculated flow result The actual flow rate is calculated using the first calculation module. It can be directly obtained by presetting the volume flow rate of the fluid injected into the pipeline.

[0170] In some embodiments, when determining the calibration coefficient, the steps further include: repeating the preliminary experiment under different experimental conditions to obtain the calibration coefficient under different experimental conditions, wherein the experimental conditions include at least the number of modes;

[0171] Accordingly, before correcting the volume flow, the method further includes:

[0172] The current conditions are acquired, and the experimental conditions are matched according to the current conditions to obtain calibration coefficients matched under the current conditions.

[0173] Example 3

[0174] See also Figure 5The present invention provides a multi-modal ultrasonic flow fusion method, comprising the following steps:

[0175] S200, using a first probe and a second probe to send a first transmit signal and a second transmit signal, respectively, and correspondingly collecting a first receive signal and a second receive signal; wherein the first transmit signal or the second transmit signal generates at least three modes during propagation in the system to be measured, and the first receive signal or the second receive signal includes receive signals in the at least three modes;

[0176] Specifically, when one of the probes sends a sinusoidal pulse beam (a beam consisting of multiple cycles), that is, when it transmits a signal, the corresponding other probe receives 6 ultrasonic modes with different propagation speeds (such as Figure 2 Mode 1, Mode 2...Mode 6 in the figure), that is, each mode corresponds to one end receiving the signal.

[0177] S201, selecting at least three modes from the modes generated in S200;

[0178] S202, dividing the at least three modes selected in S201 into at least two mode groups, wherein one of the mode groups includes two modes;

[0179] S203, defining two modes in the mode group as a first mode and a second mode, respectively; obtaining a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode, respectively, from the received signal, and calculating the volume flow rate in the mode group using the following model;

[0180] in, ;

[0181]

[0182] ;

[0183] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius in the system to be measured;

[0184] S205: Calculate a flow rate mean based on at least two of the volume flow rates.

[0185] In some embodiments, before S200, the step further includes:

[0186] S100, pre-building a modality quantity selection model, wherein the step of pre-building the modality quantity selection model includes setting at least two modality quantity ranges, and matching corresponding modality selection quantities for the at least two modality quantity ranges respectively;

[0187] Accordingly, in S200, a first transmission signal and a second transmission signal are respectively transmitted using a first probe and a second probe, and a first reception signal and a second reception signal are correspondingly collected; wherein the first transmission signal or the second transmission signal generates at least three modes during propagation in the system to be measured, and the first reception signal or the second reception signal includes reception signals in the at least three modes;

[0188] S201, matching a corresponding modality selection quantity in the modality quantity selection model according to the quantity of the modalities generated in S200, wherein the modality selection quantity is greater than or equal to three, and selecting at least three modes from the modalities according to the modality selection quantity;

[0189] S202, dividing the selected at least three modalities into at least two modal groups, wherein one modal group includes two modalities;

[0190] Wherein, when the modes are divided into at least two mode groups, the mode groups can be determined according to the total number of modes and the number of selected modes. For example, see Figure 2 The figure shows the case where the total number of modes is 6. At this time, the total number of modes is relatively small, and three or four modes can be selected and divided into two mode groups. For another example, when the total number of modes is large (not shown in the figure), a larger number of modes (preferably an even number of modes) can be selected and combined into three or more mode groups.

[0191] S203, defining two modes in the mode group as a first mode and a second mode, respectively; obtaining a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode, respectively, from the received signal, and calculating the volume flow rate in the mode group using the following formula;

[0192] in, ;

[0193]

[0194] ;

[0195] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the radius of the pipe to be measured;

[0196] Among them, when When , it means the fluid in the pipe is flowing in the forward direction.

[0197]

[0198] when When , it means the fluid in the pipe is flowing in the reverse direction.

[0199]

[0200] S203 is executed for different mode groups respectively to obtain the corresponding volume flow rates under multiple mode groups.

[0201] It should be noted that the first coefficient in this paper , the second coefficient and the third coefficient The names are only used for distinction and can be understood as representative characters. They are obtained by different calculation methods according to the first downstream propagation time, the first upstream propagation time, the second downstream propagation time and the second upstream propagation time, and have no actual meaning.

[0202] S205: Calculate a flow rate mean value based on the volume flow rate(s).

[0203] In some embodiments, before S205, the step further includes:

[0204] S204: Correct the volume flow rate by multiplying the volume flow rate by a pre-obtained calibration coefficient.

[0205] In some embodiments, the method for obtaining the calibration coefficient includes:

[0206] S41, performing a preliminary experiment under the experimental conditions to obtain the actual flow results of the current mode group in the calibration area under the experimental conditions and calculated flow results ; Wherein, the calibration area is an area corresponding to at least two modes among the multiple modes obtained through the preliminary experiment;

[0207] S42, based on the actual flow results And the calculated flow results Calculate the calibration coefficient ;

[0208] ;

[0209] Among them, the calculated flow result The actual flow rate is calculated using the above steps S100-S203; It can be directly obtained by presetting the volume flow rate of the fluid injected into the pipeline.

[0210] It should be noted that the calibration coefficient can be one or more. For example, when there is one modal group, there is only one calibration coefficient; when there are two modal groups, there are two calibration coefficients, corresponding to the two modal groups respectively, and so on. In the actual measurement process, the mode selected in the modal group is matched with the modal group corresponding to the calibration coefficient to obtain the calibration coefficient in the current modal group.

[0211] In some embodiments, the step of obtaining the calibration coefficient further includes:

[0212] S43, repeating the preliminary experiment under different experimental conditions to obtain calibration coefficients under different experimental conditions, where the experimental conditions at least include the number of modes;

[0213] Correspondingly, in S204, before correcting the volume flow, the method further includes: acquiring current conditions, matching the experimental conditions according to the current conditions, and obtaining calibration coefficients matching the current conditions.

[0214] In some embodiments, in S204, before correcting the volume flow, the step of:

[0215] S206, obtaining current conditions and matching the current conditions with the experimental conditions, the specific steps of which include:

[0216] S61, obtaining at least three groups of received signals of at least three modes in a calibration area under current conditions, and at least three groups of standard received signals measured in at least three modes in the calibration area under experimental conditions;

[0217] S62, respectively calculating amplitude differences between the received signal and the standard received signal to obtain at least three amplitude differences;

[0218] S63, determining whether the at least three amplitude differences are all smaller than a first preset difference; if so, matching the current condition with the experimental condition;

[0219] S207: Obtain the calibration coefficient under the experimental conditions.

[0220] In some embodiments, in S206, the specific steps of matching the experimental conditions according to the current conditions include:

[0221] S64, obtaining at least three groups of received signals of at least three modes within the calibration area under current conditions;

[0222] S65, determining whether the signal lengths in the received signals all meet a first preset length threshold range; if so, matching the current condition with the experimental condition.

[0223] It should be noted that when matching the experimental conditions based on the current conditions, either only the amplitude or the signal length can be selected for matching, or both can be selected for matching. Furthermore, if a mismatch occurs, the amplitude and / or signal length can be remeasured for matching, or the excitation conditions can be adjusted or other methods can be used to reacquire the amplitude and / or signal length for matching.

[0224] In some embodiments, in S201, the specific step of selecting at least three modalities includes: determining whether the current modality satisfies a selection condition, wherein the selection condition requires that the amplitude of the received signal in the current modality is greater than a first preset amplitude threshold and / or the signal length of the received signal in the current modality is within a first preset length threshold range; if so, the modality is included in the set of selectable modalities. Specifically, determining whether the amplitude of the received signal in the current modality is greater than the first preset amplitude threshold and / or determining whether the signal length of the received signal in the current modality is within a first preset length threshold range. If at least one of the above conditions is met (including the following three situations: 1. the amplitude of the received signal in the current modality is greater than the first preset amplitude threshold, but the signal length of the received signal in the current modality is not within the first preset length threshold range; 2. the amplitude of the received signal in the current modality is less than the first preset amplitude threshold, but the signal length of the received signal in the current modality is within the first preset length threshold range; 3. the amplitude of the received signal in the current modality is greater than the first preset amplitude threshold, and the signal length of the received signal in the current modality is within the first preset length threshold range), the modality is included in the set of selectable modalities.

[0225] In some embodiments, the specific steps of selecting at least three modes from the modes according to the mode selection number also include: determining whether the amplitude of the received signal under the current mode is less than a second preset amplitude threshold; if so, selecting the mode; otherwise, not selecting the mode.

[0226] See also Figure 2 , different amplitudes and durations are collected correspondingly under different modes; in this article, the first preset amplitude threshold can be a specific amplitude determined by the user based on the amplitudes of multiple modes under different experimental conditions obtained based on preliminary experiments, but at the same time, the amplitude should be lower than the safe amplitude value (if the sound wave amplitude is too large, it may cause damage to the equipment. Therefore, the safe amplitude value refers to the maximum amplitude value that will not cause damage to the equipment; accordingly, the second preset amplitude threshold can be an amplitude value between the first preset amplitude threshold and the safe amplitude value); accordingly, the first preset length threshold range can be a specific signal length threshold range determined by the user based on the signal lengths of multiple modes under different experimental conditions obtained based on preliminary experiments; the first preset time threshold can be a specific time value determined by the user based on the durations of multiple modes under different experimental conditions obtained based on preliminary experiments.

[0227] In summary, for the above-mentioned large-diameter, high-flow-rate scenario, the present application compensates for the error by measuring the ultrasonic transmission time difference between the finite modes (dual modes) under the finite mode group, and by measuring the upstream and downstream time differences between two different modes (which includes the upstream and downstream time difference of the first mode, the upstream and downstream time difference under the second mode, and the multi-dimensional time difference of the cross upstream and downstream time difference under the first mode and the second mode), and using the multi-dimensional time difference information to compensate for the measurement error under a single mode; and correcting and fusing the finite volume flow data obtained after compensation, and then obtaining the compensated and corrected comprehensive volume flow, which greatly improves the accuracy of flow measurement in large-diameter pipes.

[0228] First of all, the present application provides a high-intensity, wide-amplitude modal data acquisition mechanism, which imposes dual restrictions on the amplitude and the length of the acquired signal, and selects the two most representative modes. On the one hand, the mode with a larger amplitude can retain the integrity of the original signal to the greatest extent and reduce the interference of other factors (such as noise); on the other hand, the signal length is restricted, and the mode of the received signal with a larger signal length is selected within the preset length threshold range. A wider data acquisition window can be divided under this mode, thereby obtaining more data point information, and then using multiple data point information as raw data to calculate more accurate upstream and downstream time, thereby improving the accuracy of flow measurement without excessively increasing the data acquisition and processing volume signals.

[0229] Furthermore, the present application adaptively selects a finite number of modes that match the total number of current ultrasonic modes, divides the selected finite modes into a finite number of mode groups, calculates the flow rate separately, and finally corrects and integrates multiple flow rate results, thereby greatly improving the measurement accuracy of volume flow.

[0230] Among them, in the correction process, the corresponding calibration coefficients are measured for different experimental conditions (such as different numbers of modes), which can make it possible to match the specified calibration coefficient under the mode according to the current mode in the process of measuring volume flow, thereby further improving the accuracy; further, before matching the calibration coefficients, by performing a preliminary screening of the current conditions, for example, limiting the signal length and amplitude in the calibration area, and selecting a more reliable calibration coefficient, it can effectively avoid the problem of inaccurate received signals (modes) caused by, for example, unstable excitation signals or other accidental factors.

[0231] Example 4

[0232] See also Figure 6 The present invention provides a multi-modal ultrasonic flow fusion system, comprising:

[0233] A second acquisition module is configured to transmit a first transmission signal and a second transmission signal using a first probe and a second probe, respectively, and to acquire a first reception signal and a second reception signal accordingly; wherein the first transmission signal or the second transmission signal generates at least three modes during propagation in the system to be measured, and the first reception signal or the second reception signal includes reception signals in the at least three modes;

[0234] A second modality selection module: configured to select at least three modalities from the modalities collected by the second collection module;

[0235] A modality group division module: configured to divide the at least three modalities selected by the second modality selection module into at least two modality groups, wherein one modality group includes two modalities;

[0236] a data acquisition module configured to define two modes in the modal group as a first mode and a second mode, respectively; and acquire, through the received signal, a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode, respectively;

[0237] A second calculation module is configured to calculate the volume flow rate under the modal group using the following model; and calculate the flow mean value according to the volume flow rate;

[0238] in, ;

[0239]

[0240] ;

[0241] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius in the system to be tested.

[0242] In some specific embodiments, the multimodal ultrasonic flow fusion system includes:

[0243] A model construction module is configured to pre-construct a modality quantity selection model, wherein the step of pre-constructing the modality quantity selection model includes setting at least two modality quantity ranges and matching corresponding modality selection quantities for the at least two modality quantity ranges respectively;

[0244] A second acquisition module is configured to transmit a first transmission signal and a second transmission signal using a first probe and a second probe, respectively, and to acquire a first reception signal and a second reception signal correspondingly; wherein the first transmission signal or the second transmission signal generates at least three modes during propagation in the system to be measured;

[0245] A modality quantity matching module is configured to match a corresponding modality selection quantity in the modality quantity selection model according to the quantity of modalities collected by the second collection module, wherein the modality selection quantity is greater than or equal to three;

[0246] A modality group division module is configured to select at least three modalities from the modalities according to the modality selection quantity, and divide the selected modalities into at least two modality groups, wherein one modality group includes two modalities;

[0247] a data acquisition module configured to define two modes in the modal group as a first mode and a second mode, respectively; and acquire, through the received signal, a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode, respectively;

[0248] A second calculation module is configured to calculate the volume flow rate under the modal group using the following formula; and calculate the flow mean value according to the volume flow rate;

[0249] in, ;

[0250]

[0251] ;

[0252] Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius in the system to be tested.

[0253] In some embodiments, further comprising:

[0254] The second correction module is configured to correct the volume flow by multiplying the volume flow by a pre-obtained calibration coefficient.

[0255] In some embodiments, when obtaining the calibration coefficient, the second correction module is specifically configured to: perform a preliminary experiment under experimental conditions to obtain the actual flow results of the current mode group in the calibration area under the experimental conditions. and calculated flow results ;

[0256] According to the actual flow results And the calculated flow results Calculate the calibration coefficient ;in,

[0257] .

[0258] In some embodiments, when obtaining the calibration coefficient, the second correction module is further configured to repeat the preliminary experiment under different experimental conditions to obtain the calibration coefficient under different experimental conditions, and the experimental conditions include at least the number of modes; accordingly, before correcting the volume flow, the second correction module is also configured to obtain the current conditions, and match the experimental conditions according to the current conditions to obtain the calibration coefficient matched under the current conditions.

[0259] In some embodiments, when the modal group division module selects at least three modes from the modalities according to the modal selection quantity, it is specifically configured to determine whether the current modality meets the selection conditions, and the selection conditions require that the amplitude of the received signal under the current modality is greater than a first preset amplitude threshold, and / or the signal length of the received signal under the current modality is consistent with a first preset length threshold range; if so, the modality is selected, otherwise the modality is not selected.

[0260] In some embodiments, the modality group division module is further configured to determine whether the amplitude of the received signal in the current modality is less than a second preset amplitude threshold; if so, the modality is selected; otherwise, the modality is not selected.

[0261] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0262] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A temperature-adaptive ultrasonic flow measurement method, characterized in that: Including steps: S101, using a first probe and a second probe to send a first transmit signal and a second transmit signal, respectively, and correspondingly collecting a first receive signal and a second receive signal; wherein the first transmit signal or the second transmit signal generates multiple modes during propagation in a system to be measured, and the first receive signal or the second receive signal includes receive signals in the multiple modes; S102, selecting two modes from the multiple modes, and defining the two selected modes as a first mode and a second mode respectively; S103, acquiring, according to the received signal, a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode; S104: Calculate the volume flow rate using the following model based on the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time: ； ； Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius of the system to be measured.

2. The temperature-adaptive ultrasonic flow measurement method according to claim 1, characterized in that: In S102, the specific steps of selecting the two modes include: S1021, determining whether the current mode meets a selection condition, wherein the selection condition requires that the amplitude of the received signal in the current mode is greater than a first preset amplitude threshold and the signal length of the received signal in the current mode is within a first preset length threshold range; if so, classifying the mode into the selectable mode set; S1023: Select two modalities from the optional modality set, and define the two modalities as a first modality and a second modality, respectively.

3. The temperature-adaptive ultrasonic flow measurement method according to claim 2, characterized in that: Before S1023, the following steps are also included: S1022: Determine whether the number of modes in the optional mode set is greater than or equal to two. If so, execute S1023; otherwise, adjust the first preset amplitude threshold according to the first decrement until the number of modes satisfies the requirement of being greater than or equal to two.

4. A temperature-adaptive ultrasonic flow measurement method according to claim 2 or 3, characterized in that: In step S1023, the specific steps of selecting two modes from the optional mode set include: when the number of modes is greater than two, selecting the mode with the largest amplitude of the received signal as the first mode, and selecting the mode with the amplitude of the received signal closest to the first amplitude of the first mode as the second mode.

5. The temperature-adaptive ultrasonic flow measurement method according to claim 1, characterized in that: Also includes the steps: S105 , correcting the volume flow obtained in S104 using a preset correction rule, wherein the correction rule is to multiply the volume flow by a pre-obtained calibration coefficient.

6. A temperature-adaptive ultrasonic flow measurement system, characterized in that: include: A first acquisition module is configured to transmit a first transmission signal and a second transmission signal using a first probe and a second probe, respectively, and to acquire a first reception signal and a second reception signal accordingly; wherein the first transmission signal or the second transmission signal generates multiple modes during propagation in the system to be measured, and the first reception signal or the second reception signal includes reception signals under the multiple modes; A first mode selection module is configured to select two modes from the multiple modes and define the two modes as a first mode and a second mode respectively; a time acquisition module configured to respectively acquire, through the received signal, a first downstream propagation time and a first upstream propagation time in the first mode, and a second downstream propagation time and a second upstream propagation time in the second mode; A first calculation module is configured to calculate a volume flow rate using the following model according to the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time; ； ； Where, is the volume flow rate, is the first downstream propagation time, is the first countercurrent propagation time, is the second downstream propagation time, is the second countercurrent propagation time, is the first coefficient, is the second coefficient, is the third coefficient, is the fluid flow velocity, is the distance between the first probe and the second probe, is the pipe radius of the system to be measured.

7. The temperature-adaptive ultrasonic flow measurement system according to claim 6, characterized in that: The first mode selection module is specifically configured as follows: Determine whether the current mode meets a selection condition, wherein the selection condition requires that the amplitude of the received signal in the current mode is greater than a first preset amplitude threshold, and the signal length of the received signal in the current mode is within a first preset length threshold range; if so, classify the mode into an optional mode set; select two modes from the optional mode set, and define the two modes as a first mode and a second mode, respectively.

8. The temperature-adaptive ultrasonic flow measurement system according to claim 7, characterized in that: Also includes: A modality number determination module is configured to determine whether the number of modalities in the optional modality set is greater than or equal to two; An adjustment module is configured to adjust the first preset amplitude threshold according to a first decrement when the number of modes in the optional mode set is less than two, until the number of modes satisfies a condition of being greater than or equal to two.

9. The temperature-adaptive ultrasonic flow measurement system according to claim 7, characterized in that: The first mode selection module is specifically configured to: when the number of modes is greater than two, select the mode with the largest amplitude of the received signal as the first mode, and select the mode with the amplitude of the received signal closest to the first amplitude of the first mode as the second mode.

10. The temperature-adaptive ultrasonic flow measurement system according to claim 6, characterized in that: Also includes: The first flow correction module is configured to correct the volume flow calculated by the first calculation module using a preset correction rule, wherein the correction rule is to multiply the volume flow by a pre-obtained calibration coefficient.

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