Signal processing method and system for improving bubble adaptability of time-difference ultrasonic flowmeter

Abstract

The present invention provides a signal processing method for improving the bubble adaptability of a time difference ultrasonic flowmeter, solves the problem that the measurement performance of the time difference ultrasonic flowmeter is reduced or the function is lost when bubbles exist in the measured liquid, performs feature recognition on the statistics of upstream and downstream time signals according to the signal characteristics of the time difference ultrasonic flowmeter, adopts the clustering algorithm idea to extract flow velocity information, extracts the flow velocity information of the measured liquid from the fluctuation signal disturbed by the bubble, overcomes the influence of the bubble on the flow measurement, effectively improves the bubble adaptability of the time difference ultrasonic flowmeter, and expands the application scope of the time difference ultrasonic flowmeter.

Description

Technical Field

[0001] The invention belongs to the field of flow measurement, and relates to a signal processing method and a system for improving the bubble adaptability of a time difference method ultrasonic flow meter. Background Art

[0002] For ultrasonic flow meters based on the time difference method, when there are bubbles in the measured liquid, due to the large difference between the acoustic impedance of the liquid and the acoustic impedance of the gas, the ultrasonic wave will be reflected or scattered when it is incident on the surface of the bubble. The propagation path of the ultrasonic wave in the liquid medium containing bubbles becomes extremely complicated, resulting in fluctuations in the received signal, affecting the reliable operation of the ultrasonic flow meter.

[0003] During the flow measurement process, the existing ultrasonic flowmeter based on the time difference method usually performs filtering processing on the upstream and downstream time difference data, such as mean filtering, median filtering, etc. When there are bubbles in the measured medium, the received sound wave signal will jump significantly, resulting in changes in the statistical characteristics of the upstream and downstream time difference data. At this time, if the upstream and downstream time difference data are processed using signal processing techniques such as mean filtering and median filtering, it will no longer be effective. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, the present invention provides a signal processing method and system for improving the bubble adaptability of a time-difference ultrasonic flowmeter, and solves the problem that the measurement performance of the time-difference ultrasonic flowmeter is reduced or the function is lost when bubbles exist in the measured liquid.

[0005] The technical solution of the present invention is:

[0006] A signal processing method for improving bubble adaptability of a time difference ultrasonic flowmeter, comprising:

[0007] (1) Set the downstream and upstream propagation time data buffers respectively, set the buffer size to M, and initialize them;

[0008] (2) transmitting a downstream ultrasonic pulse and waiting for the downstream ultrasonic signal to trigger a threshold interrupt. If the interrupt is valid, obtaining the downstream propagation time data of the ultrasonic flow meter and storing it in the downstream propagation time data buffer;

[0009] (3) transmitting a countercurrent ultrasonic pulse and waiting for the countercurrent ultrasonic signal to trigger a threshold interrupt. If the interrupt is valid, reading the countercurrent propagation time data of the ultrasonic flow meter and storing it in the countercurrent propagation time data buffer;

[0010] (4) performing data feature discrimination on the data in the downstream propagation time data buffer area and grouping the data;

[0011] (5) For the grouped downstream propagation time data, for the groups whose data counts are not zero, calculate the average value within the group to obtain the downstream propagation time mean array;

[0012] (6) performing data feature discrimination on the data in the countercurrent propagation time data buffer area and grouping the data;

[0013] (7) For the grouped countercurrent propagation time data, for the groups whose data counts are not zero, calculate the average value within the group to obtain the countercurrent propagation time mean array;

[0014] (8) Subtract each non-zero element in the downstream propagation time mean array from each non-zero element in the upstream propagation time mean array to obtain the time difference. If the time difference satisfies the given threshold range, the time differences that meet the conditions are accumulated to obtain the time difference accumulation sum, and the number of accumulations is recorded, and then step (9) is entered; otherwise, return to step (2);

[0015] (9) The average time difference is obtained by summing up the time differences and dividing by the number of accumulations, i.e. the filtered time difference, which is used for flow calculation.

[0016] Furthermore, the downstream propagation time data of the ultrasonic flowmeter is t 1 , that is, the time from when the ultrasonic pulse is emitted from the upstream transmitting end to when the downstream receiving end receives the ultrasonic signal and triggers the threshold interruption;

[0017] The ultrasonic flowmeter backflow propagation time data is t 2 , that is, the time from when the ultrasonic pulse is emitted from the downstream transmitting end to when the upstream receiving end receives the ultrasonic signal and triggers the threshold interrupt.

[0018] Furthermore, the flow rate is calculated by the filtered time difference using the following formula:

[0019]

[0020] Among them, Q v is the volume flow rate, D is the inner diameter of the pipeline, L is the distance between the upstream and downstream ultrasonic probes, c 0 is the liquid sound speed, is the time difference after filtering.

[0021] Furthermore, the data in the downstream propagation time data buffer are sorted from small to large to obtain the maximum value and minimum value of the downstream propagation time data buffer, which are TOF_UP_MAX and TOF_UP_MIN respectively; the data in the upstream propagation time data buffer are sorted from small to large to obtain the maximum value and minimum value of the upstream propagation time data buffer, which are TOF_DOWN_MAX and TOF_DOWN_MIN respectively.

[0022] Furthermore, the data in the downstream propagation time data buffer area is subjected to data feature discrimination and grouping, specifically:

[0023] Determine whether the difference between the maximum and minimum values ​​in the downstream propagation time data buffer is greater than the set threshold; if it is greater than the set threshold, take the maximum value as the upper limit and the minimum value as the lower limit, and divide N intervals between the lower limit and the upper limit at equal intervals, each equally divided interval as a group, and a total of N groups; put the data in the downstream propagation time data buffer into N equally divided intervals according to the numerical value, and record the number of downstream propagation time data in each interval; if it is not greater than the set threshold, no grouping, that is, 1 group, and the number of data in the group is the size of the buffer.

[0024] Furthermore, the data in the countercurrent propagation time data buffer area is subjected to data feature discrimination and grouping, specifically:

[0025] Determine whether the difference between the maximum and minimum values ​​in the countercurrent propagation time data buffer is greater than the set threshold; if it is greater than the set threshold, take the maximum value as the upper limit and the minimum value as the lower limit, and divide N intervals between the lower limit and the upper limit at equal intervals, each equally divided interval as a group, and a total of N groups; put the data in the countercurrent propagation time data buffer into N equally divided intervals according to the value size, and record the number of countercurrent propagation time data in each interval; if it is not greater than the set threshold, no grouping, that is, 1 group, and the number of data in the group is the size of the buffer.

[0026] Furthermore, the number N of equal groups is not less than 10.

[0027] Furthermore, the downstream and upstream propagation time data buffers are initialized to 0, the data buffer size is M, and M≥10.

[0028] Furthermore, the present invention also proposes a signal processing system for improving the bubble adaptability of a time difference ultrasonic flowmeter, comprising:

[0029] Buffer area setting module: set the downstream and upstream propagation time data buffer areas respectively, set the buffer area size to M, and initialize it;

[0030] Pulse transmitting module: transmits downstream ultrasonic pulses, waits for the downstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, obtains the downstream propagation time data of the ultrasonic flow meter, and puts it into the downstream propagation time data buffer; transmits upstream ultrasonic pulses, waits for the upstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, reads the upstream propagation time data of the ultrasonic flow meter, and puts it into the upstream propagation time data buffer;

[0031] Data feature identification module: performing data feature identification on the data in the downstream propagation time data buffer area and grouping; for the grouped downstream propagation time data, for the groups whose data counts are not zero, calculating the average value within the group, and obtaining the downstream propagation time mean array; performing data feature identification on the data in the upstream propagation time data buffer area and grouping; for the grouped upstream propagation time data, for the groups whose data counts are not zero, calculating the average value within the group, and obtaining the upstream propagation time mean array;

[0032] Time difference calculation module: subtract each non-zero element in the downstream propagation time mean array from each non-zero element in the upstream propagation time mean array to obtain the time difference. If the time difference satisfies the given threshold range, the time differences that meet the conditions are accumulated to obtain the time difference cumulative sum, and the number of accumulations is recorded;

[0033] Flow calculation module: The average time difference, that is, the filtered time difference, is obtained by accumulating the time difference and dividing it by the number of accumulations, which is used for flow calculation.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The present invention is directed to an ultrasonic flow meter based on a time difference method, which can handle data fluctuations caused by the influence of bubbles compared to a transmission time difference method.

[0036] (2) The present invention is directed to an ultrasonic flow meter based on a time difference method. Compared with a transmission time difference method, the present invention can also filter ultrasonic signal data in the absence of bubbles. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of ultrasonic excitation signal and receiving signal under normal conditions;

[0038] Figure 2 is a schematic diagram of the signal after attenuation;

[0039] Figure 3 is a schematic diagram of the enhanced signal;

[0040] Figure 4 The downstream and upstream propagation time data of bubbles in the embodiment;

[0041] Figure 5 A comparison diagram of the traditional time difference filtering method in the embodiment and the time difference filtering method of the present invention;

[0042] Figure 6 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0043] like Figure 1The figure shows the ultrasonic excitation signal and the receiving signal under normal conditions. When there is bubble flow in the liquid medium, the measured propagation time value is T0. Figure 1 The signal may decay to Figure 2 Since the comparison level remains unchanged, there is a difference in the amplitude of the two received signals. Figure 2 When the flow rate is the same, the voltage triggering time is shifted later, that is, the measured propagation time value T1 is greater than T0. Figure 1 The signal may be enhanced to Figure 3 The state of the comparison voltage trigger occurs in advance, that is, the measured value of the propagation time T2 is less than T0. This is the reason why the propagation time data fluctuates when bubbles exist.

[0044] Aiming at the problem that the measurement performance of a time-difference ultrasonic flowmeter is degraded or the function is lost when bubbles exist in the measured liquid, the present invention proposes a signal processing method, which performs feature recognition on the statistics of upstream and downstream time signals according to the signal characteristics of the time-difference ultrasonic flowmeter, adopts the idea of ​​clustering algorithm to extract flow velocity information, extracts the flow velocity information of the measured liquid from the fluctuation signal disturbed by bubbles, overcomes the influence of bubbles on flow measurement, effectively improves the bubble adaptability of the time-difference ultrasonic flowmeter, and expands the application scope of the time-difference ultrasonic flowmeter.

[0045] Specifically, Figure 6 As shown, the signal processing method for improving the bubble adaptability of the time difference ultrasonic flowmeter proposed by the present invention comprises the following steps:

[0046] a) Set the downstream and upstream propagation time data buffers respectively and initialize them to 0. The buffer size is M, which can be selected according to the actual application requirements (M is generally not less than 10);

[0047] b) Emitting downstream ultrasonic pulses, waiting for the downstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, obtaining the downstream propagation time data of the ultrasonic flowmeter, and putting it into the downstream propagation time data buffer area; the downstream propagation time data of the ultrasonic flowmeter is t 1 , that is, the time from when the ultrasonic pulse is emitted from the upstream transmitting end to when the downstream receiving end receives the ultrasonic signal and triggers the threshold interruption;

[0048] In the present invention, generally speaking, the downstream ultrasonic signal or the upstream ultrasonic signal is generally at the millivolt level, triggering a threshold interrupt, so that the interrupt is effective when the voltage amplitude of the downstream ultrasonic signal or the upstream ultrasonic signal reaches a set threshold, such as 1V.

[0049] c) Emitting a countercurrent ultrasonic pulse, waiting for the countercurrent ultrasonic signal to trigger a threshold interrupt, if the interrupt is valid, reading the ultrasonic flow meter countercurrent propagation time data and putting it into the countercurrent propagation time data buffer; the ultrasonic flow meter countercurrent propagation time data is t2 , that is, the time from when the ultrasonic pulse is emitted from the downstream transmitting end to when the upstream receiving end receives the ultrasonic signal and triggers the threshold interrupt.

[0050] d) Determine whether the difference between the maximum value and the minimum value in the downstream propagation time data buffer is greater than a set threshold; if so, take the maximum value as the upper limit value and the minimum value as the lower limit value, and divide the lower limit value and the upper limit value into N intervals (N is generally not less than 10) at equal intervals, and each equally divided interval is a group, for a total of N groups; put the data in the downstream propagation time data buffer into N equally divided intervals according to the numerical value, and record the number of downstream propagation time data in each interval; if not, do not group, that is, 1 group, and the number of data in the group is the size of the buffer;

[0051] Sort the data in the downstream propagation time data buffer from small to large, and obtain the maximum value and minimum value of the downstream propagation time data buffer, which are TOF_UP_MAX and TOF_UP_MIN respectively;

[0052] e) for the grouped downstream propagation time data, for the groups whose data counts are not zero, calculate the average value within the group to obtain the downstream propagation time mean array;

[0053] Determine whether the difference between the maximum and minimum values ​​in the countercurrent propagation time data buffer is greater than the set threshold; if yes, take the maximum value as the upper limit, take the minimum value as the lower limit, divide the lower limit and the upper limit into N intervals (N is generally not less than 10) at equal intervals, and each equally divided interval is a group, for a total of N groups; put the data in the countercurrent propagation time data buffer into N equally divided intervals according to the numerical value, and record the number of countercurrent propagation time data in each interval; if no, do not group, that is, 1 group, and the number of data in the group is the size of the buffer;

[0054] The data in the upstream propagation time data buffer are sorted from small to large to obtain the maximum value and minimum value of the upstream propagation time data buffer, which are TOF_DOWN_MAX and TOF_DOWN_MIN, respectively.

[0055] f) for the grouped countercurrent propagation time data, for the groups whose data counts are not zero, calculate the average value within the group to obtain the countercurrent propagation time mean array;

[0056] g) Subtract each non-zero element in the downstream propagation time mean array from each non-zero element in the upstream propagation time mean array to obtain the time difference. If the time difference satisfies the given threshold range, the time differences that meet the conditions are accumulated to obtain the cumulative sum of the time differences, and the number of accumulations is recorded;

[0057] h) Use the time difference accumulation and divide the accumulation times to obtain the average time difference, that is, the filtered time difference, which is used for flow calculation. The calculation formula is as follows:

[0058]

[0059] Among them, Q v is the volume flow rate, D is the inner diameter of the pipeline, L is the distance between the upstream and downstream ultrasonic probes, c 0 is the liquid sound speed, is the time difference after filtering.

[0060] The present invention also provides a signal processing system for improving the bubble adaptability of a time difference ultrasonic flowmeter, the system comprising:

[0061] Buffer area setting module: set the downstream and upstream propagation time data buffer areas respectively, set the buffer area size to M, and initialize it;

[0062] Pulse transmitting module: transmits downstream ultrasonic pulses, waits for the downstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, obtains the downstream propagation time data of the ultrasonic flow meter, and puts it into the downstream propagation time data buffer; transmits upstream ultrasonic pulses, waits for the upstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, reads the upstream propagation time data of the ultrasonic flow meter, and puts it into the upstream propagation time data buffer;

[0063] Data feature identification module: performing data feature identification on the data in the downstream propagation time data buffer area and grouping; for the grouped downstream propagation time data, for the groups whose data counts are not zero, calculating the average value within the group, and obtaining the downstream propagation time mean array; performing data feature identification on the data in the upstream propagation time data buffer area and grouping; for the grouped upstream propagation time data, for the groups whose data counts are not zero, calculating the average value within the group, and obtaining the upstream propagation time mean array;

[0064] Time difference calculation module: subtract each non-zero element in the downstream propagation time mean array from each non-zero element in the upstream propagation time mean array to obtain the time difference. If the time difference satisfies the given threshold range, the time differences that meet the conditions are accumulated to obtain the time difference cumulative sum, and the number of accumulations is recorded;

[0065] Flow calculation module: The average time difference, that is, the filtered time difference, is obtained by accumulating the time difference and dividing it by the number of accumulations, which is used for flow calculation.

[0066] Example:

[0067] The test was conducted with water as the medium and bubbles mixed in the water. The test results are as follows: Figure 4 and Figure 5 shown. Figure 4 These are the measured data of the downstream propagation time signal and the upstream propagation time in the process from the presence of bubbles to the absence of bubbles in the measured medium (water) of the ultrasonic flowmeter. It can be seen that when there are bubbles in the measured medium, the downstream and upstream propagation time data fluctuate violently, and when there are no bubbles in the measured medium, the downstream and upstream propagation time data are stable.

[0068] Figure 5 A comparison is given between the conventional mean filtering and the filtering using the method of the present invention for the forward and reverse flow time difference. It can be seen that the method of the present invention is applicable to the case where the measured medium contains bubbles.

[0069] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0070] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A signal processing method for improving the bubble adaptability of a time difference ultrasonic flowmeter, characterized in that include: (1) Set the downstream and upstream propagation time data buffers respectively, set the buffer size to M, and initialize them; (2) transmitting a downstream ultrasonic pulse and waiting for the downstream ultrasonic signal to trigger a threshold interrupt. If the interrupt is valid, obtaining the downstream propagation time data of the ultrasonic flow meter and storing it in the downstream propagation time data buffer; (3) transmitting a countercurrent ultrasonic pulse and waiting for the countercurrent ultrasonic signal to trigger a threshold interrupt. If the interrupt is valid, reading the countercurrent propagation time data of the ultrasonic flow meter and storing it in the countercurrent propagation time data buffer; (4) Data characteristics are identified and grouped in the downstream propagation time data buffer area; specifically: Determine whether the difference between the maximum value and the minimum value in the downstream propagation time data buffer is greater than a set threshold; if it is greater than the set threshold, take the maximum value as the upper limit value and the minimum value as the lower limit value, and divide N intervals between the lower limit value and the upper limit value at equal intervals, each equally divided interval is a group, and there are N groups in total; put the data in the downstream propagation time data buffer into N equally divided intervals according to the value size, and record the number of downstream propagation time data in each interval; If it is not greater than the set threshold, there is no grouping, that is, 1 group, and the number of data in the group is the buffer size; (5) For the grouped downstream propagation time data, for the groups whose data counts are not zero, calculate the average value within the group to obtain the downstream propagation time mean array; (6) Data characteristics are identified and grouped in the countercurrent propagation time data buffer area; specifically: Determine whether the difference between the maximum value and the minimum value in the countercurrent propagation time data buffer is greater than a set threshold; if it is greater than the set threshold, take the maximum value as the upper limit value and the minimum value as the lower limit value, and divide N intervals between the lower limit value and the upper limit value at equal intervals, each equally divided interval is a group, and there are N groups in total; put the data in the countercurrent propagation time data buffer into N equally divided intervals according to the value size, and record the number of countercurrent propagation time data in each interval; If it is not greater than the set threshold, there is no grouping, that is, 1 group, and the number of data in the group is the buffer size; (7) For the grouped countercurrent propagation time data, for the groups whose data counts are not zero, calculate the average value within the group to obtain the countercurrent propagation time mean array; (8) Subtract each non-zero element in the downstream propagation time mean array from each non-zero element in the upstream propagation time mean array to obtain the time difference. If the time difference satisfies the given threshold range, the time differences that meet the conditions are accumulated to obtain the time difference accumulation sum, and the number of accumulations is recorded, and then step (9) is entered; otherwise, return to step (2); (9) The average time difference is obtained by summing up the time differences and dividing by the number of accumulations, i.e. the filtered time difference, which is used for flow calculation.

2. A signal processing method for improving bubble adaptability of a transit-time ultrasonic flowmeter according to claim 1, characterized in that: The downstream propagation time data of the ultrasonic flowmeter is t1, which is the time from the ultrasonic pulse being emitted from the upstream transmitting end to the downstream receiving end receiving the ultrasonic signal and triggering the threshold interruption; The upstream propagation time data of the ultrasonic flow meter is t2, which is the time from the ultrasonic pulse being emitted from the downstream transmitting end to the upstream receiving end receiving the ultrasonic signal and triggering the threshold interruption.

3. The signal processing method for improving the bubble adaptability of a transit-time ultrasonic flowmeter according to claim 1, characterized in that: The flow rate is calculated by the filtered time difference using the following formula: Among them, Q v is the volume flow rate, D is the inner diameter of the pipeline, L is the distance between the upstream and downstream ultrasonic probes, c0 is the liquid sound velocity, is the time difference after filtering.

4. The signal processing method for improving the bubble adaptability of a transit-time ultrasonic flowmeter according to claim 1, characterized in that: The data in the downstream propagation time data buffer are sorted from small to large to obtain the maximum and minimum values ​​of the downstream propagation time data buffer, which are TOF_UP_MAX and TOF_UP_MIN respectively; the data in the upstream propagation time data buffer are sorted from small to large to obtain the maximum and minimum values ​​of the upstream propagation time data buffer, which are TOF_DOWN_MAX and TOF_DOWN_MIN respectively.

5. The signal processing method for improving the bubble adaptability of a transit-time ultrasonic flowmeter according to claim 1, characterized in that: The number of equal groups N is not less than 10.

6. The signal processing method for improving the bubble adaptability of a transit-time ultrasonic flowmeter according to claim 1, characterized in that: The downstream and upstream propagation time data buffers are initialized to 0, the data buffer size is M, and M≥10.

7. A signal processing system for improving the bubble adaptability of a transit-time ultrasonic flowmeter based on the signal processing method for improving the bubble adaptability of a transit-time ultrasonic flowmeter according to claim 1, characterized in that include: Buffer area setting module: set the downstream and upstream propagation time data buffer areas respectively, set the buffer area size to M, and initialize it; Pulse transmitting module: transmits downstream ultrasonic pulses, waits for the downstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, obtains the downstream propagation time data of the ultrasonic flow meter, and puts it into the downstream propagation time data buffer; transmits upstream ultrasonic pulses, waits for the upstream ultrasonic signal to trigger the threshold interrupt, if the interrupt is valid, reads the upstream propagation time data of the ultrasonic flow meter, and puts it into the upstream propagation time data buffer; Data feature identification module: performs data feature identification on the data in the downstream propagation time data buffer area and groups them; for the grouped downstream propagation time data, for the groups whose data counts are not zero, calculates the average value within the group to obtain the downstream propagation time mean value array; The data in the countercurrent propagation time data buffer area is subjected to data feature discrimination and grouping; for the countercurrent propagation time data after grouping, the average value within the group whose data count is not zero is calculated to obtain the countercurrent propagation time mean value array; Time difference calculation module: subtract each non-zero element in the downstream propagation time mean array from each non-zero element in the upstream propagation time mean array to obtain the time difference. If the time difference satisfies the given threshold range, the time differences that meet the conditions are accumulated to obtain the time difference cumulative sum, and the number of accumulations is recorded; Flow calculation module: The average time difference is obtained by accumulating the time difference and dividing it by the number of accumulations, that is, the filtered time difference, which is used for flow calculation; The data in the downstream propagation time data buffer area is subjected to data feature discrimination and grouping, specifically: determining whether the difference between the maximum value and the minimum value in the downstream propagation time data buffer area is greater than a set threshold value; if it is greater than the set threshold value, taking the maximum value as the upper limit value and the minimum value as the lower limit value, and dividing the lower limit value and the upper limit value into N intervals at equal intervals, each equally divided interval is a group, and a total of N groups; the data in the downstream propagation time data buffer area are respectively placed into N equally divided intervals according to the value size, and the number of downstream propagation time data in each interval is recorded; If it is not greater than the set threshold, there is no grouping, that is, 1 group, and the number of data in the group is the buffer size; The data in the countercurrent propagation time data buffer area is subjected to data feature discrimination and grouping, specifically: determining whether the difference between the maximum value and the minimum value in the countercurrent propagation time data buffer area is greater than a set threshold value; if it is greater than the set threshold value, taking the maximum value as the upper limit value and the minimum value as the lower limit value, and dividing the lower limit value and the upper limit value into N intervals at equal intervals, each equally divided interval is a group, and a total of N groups; the data in the countercurrent propagation time data buffer area are respectively placed into N equally divided intervals according to the numerical value, and the number of countercurrent propagation time data in each interval is recorded; If it is not greater than the set threshold, there is no grouping, that is, 1 group, and the number of data in the group is the buffer size.

8. The signal processing system for improving the bubble adaptability of a transit-time ultrasonic flowmeter according to claim 7, characterized in that: The downstream propagation time data of the ultrasonic flowmeter is t1, that is, the time from the ultrasonic pulse being emitted from the upstream transmitting end to the downstream receiving end receiving the ultrasonic signal and triggering the threshold interruption; the upstream propagation time data of the ultrasonic flowmeter is t2, that is, the time from the ultrasonic pulse being emitted from the downstream transmitting end to the upstream receiving end receiving the ultrasonic signal and triggering the threshold interruption; The flow rate is calculated by the filtered time difference using the following formula: Among them, Q v is the volume flow rate, D is the inner diameter of the pipeline, L is the distance between the upstream and downstream ultrasonic probes, c0 is the liquid sound velocity, and Δt is the time difference after filtering.

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