Method and system for checking and calculating the length of ultrasonic transducer sound channel

Abstract

The present invention relates to a method and system for checking and calculating the length of an ultrasonic transducer sound channel, and belongs to the field of river distance measurement. The method comprises the following steps: a pair of transducers are installed on both sides of a flow channel, and a connecting line of the transducers forms an angle with an axial direction; a pair of transducers are defined as an upstream transducer A and a downstream transducer B; transducer A and transducer B are electrically connected to a timing system respectively, and the timing system is electrically connected to a flow meter host; the propagation time of an ultrasonic wave from the downstream transducer B to the upstream transducer A is, and the propagation time from the upstream transducer A to the downstream transducer B is; considering the influence of the projection of the axial water flow velocity on the sound channel line, in the same measurement loop, the propagation time is different from the propagation time.

Description

Technical Field

[0001] The invention relates to a method and a system for checking and calculating the length of an ultrasonic transducer sound channel, and belongs to the field of river distance measurement. Background Art

[0002] The distance between the emitting surfaces of a pair of transducers in the same underwater channel of an ultrasonic flowmeter is the channel length. The channel length is used as a basic parameter to calculate the flow velocity. Deviations in the length value will lead to errors in the flow velocity calculation.

[0003] After installing the transducer in a waterless channel, use a tape measure or laser rangefinder to measure the distance between the transducer's emitting surfaces. The measured value is set in the calculation unit as the channel length. As a parameter for velocity calculation, the accuracy of the measured value depends on the accuracy of the measuring instrument and the operator's level. In a water channel, the calculation of the channel length of the underwater transducer can only be theoretically deduced based on the geometric size parameters of the channel. Since there is a certain deviation between the theoretical geometric size of the channel and the actual size, and when the transducer is placed underwater from the water, there is also a certain deviation between the design position and the actual position. These deviations will lead to errors in the calculated theoretical channel length. In the velocity formula, the channel length directly participates in the calculation, so the error in the velocity calculation is directly introduced by the channel length. Due to the lack of judgment basis, the magnitude of the error of the system is difficult to evaluate.

[0004] As a high-precision measuring instrument, the measurement accuracy of ultrasonic flowmeter depends on the precise positioning geometric parameters of the field transducer and the reasonable flow integration algorithm of the processing unit. If the deviation of the geometric parameters is large, the ultrasonic flowmeter still cannot guarantee its high-precision characteristics. Summary of the invention

[0005] The technical problem to be solved by the present invention is generally to provide a method and system for rechecking and calculating the length of the acoustic channel of an ultrasonic transducer.

[0006] To solve the above problems, the technical solution adopted by the present invention is:

[0007] In order to obtain accurate sound channel length data, a method for checking and calculating the sound channel length of an ultrasonic transducer is provided, the method comprising the following steps:

[0008] Step 1: Install a pair of transducers on both sides of the flow channel, and the connecting line of the transducers forms an angle with the axis direction. A pair of transducers is defined as an upstream transducer A and a downstream transducer B; transducer A and transducer B are electrically connected to a timing system, and the timing system is electrically connected to a flow meter host;

[0009] The propagation time of the ultrasonic wave from the downstream transducer B to the upstream transducer A is , the propagation time from the upstream transducer A to the downstream transducer B is ;

[0010] Considering the axial water velocity Projection on the channel line In the same measurement, the propagation time With propagation time The propagation time is different;

[0011] Step 2: First, during the ultrasonic propagation process, the following set of equations is obtained:

[0012] (1);

[0013] Where: - vocal tract length; — Calculate the speed of sound; —Voice channel projection velocity;

[0014] Then, the velocity projection in the direction of the sound channel is obtained by formula (1): and calculate the speed of sound ;

[0015] (1.1);

[0016] (1.2);

[0017] Secondly, the flow meter host measures the signal propagation time through the timing system, and obtains the timing time from upstream to downstream respectively: The timing from downstream to upstream is :

[0018] Again, perform parameter analysis and definition. Contains the propagation time of ultrasound from the upstream transducer A to the downstream transducer B The total transmission time of the electrical signal in the cable and the non-aqueous medium transmission time of the electrical and acoustic conversion is ; Contains the propagation time of ultrasound from downstream transducer B to upstream transducer A ;

[0019] Step 3: To obtain the exact solution:

[0020] First, conduct at least two measurement experiments in water to ensure that the total time interval between each experiment is less than the set time;

[0021] Take two measurement experiments, the measured vocal tract lengths are , The two recording times of the flow meter host measurement are and , we get the following formula:

[0022] (2);

[0023] Then, the non-aqueous medium transmission time was deduced based on the experimental process and conclusions. :

[0024] (2.1);

[0025] Based on the non-aqueous medium transmission time as a fixed value, the actual ultrasonic wave propagation time in water is corrected:

[0026] (3);

[0027] The ultrasonic forward propagation time and reverse propagation time measured by the flow meter host are calibrated to ensure that , accuracy;

[0028] Step 4: Based on parameters , , re-calculate the sound path length of transducer A and transducer B installed on site:

[0029] First, place transducer A and transducer B underwater in a channel with water.

[0030] Then, based on formula (1.2), according to the current measurement of the flow meter, , and preset channel length , find the current calculated sound speed c ;

[0031] Secondly, compare and calculate the speed of sound c The current real speed of sound V ; When calculating the speed of sound c The current real speed of sound V Inconsistency indicates that the speed of sound is calculated c There is an error, the reason is the preset channel length value There is an error;

[0032] Again, at standard atmospheric pressure The relationship between the speed of sound and the water temperature is as follows:

[0033] (4);

[0034] In the formula, is the speed of sound affected by water temperature under standard atmospheric pressure;

[0035] t n = t / 100, t is the temperature; coefficient A = 1402.39, B = 1478.5625, C = 0.69494542, D =0.16618854, E = -0.0160586, F = 0.02192692;

[0036] After that, the speed of sound in water increases with increasing pressure; the current atmospheric pressure is measured using a standard barometer , then the actual speed of sound ;

[0037] Step 5: According to the current actual sound speed V , so that the speed of sound can be calculated Equal to or close to the actual speed of sound V ;

[0038] Based on the formula , and inversely deduce the exact vocal tract length Channel length Review.

[0039] In order to obtain relevant parameter data of upstream and downstream, in step 2, first, a pulse signal is sent from the R_A end of the timing system to start timing; then, the pulse signal reaches transducer A through the cable to generate an ultrasonic signal; secondly, the ultrasonic signal propagates from transducer A to transducer B; thirdly, transducer B receives the ultrasonic signal and converts it into an electrical signal; then, the electrical signal is transmitted to the R_B end of the timing system through the cable, and the timing ends. The timing duration is ;

[0040] On the contrary, a pulse signal is sent from the R_B end of the timing system to start timing. The pulse signal reaches transducer B through the cable, generating an ultrasonic signal, which is transmitted to transducer A. After transducer A receives the ultrasonic signal, it converts the ultrasonic signal into an electrical signal, which is then transmitted to R_A through the cable, and the timing ends. The timing duration is .

[0041] In order to realize the definition of water medium, the standard for setting time is: the physical properties of the water medium in the measurement experiment remain unchanged or the change of the physical properties is lower than the set value, and the calculated sound speed c of ultrasound in the water medium does not change or the change is negligible.

[0042] The applicable temperature range of formula (4) is (0-90) ℃.

[0043] In order to achieve accurate measurement, in step 4, the average water temperature is obtained by taking the arithmetic average of all measuring points and substituting it into formula (4) to calculate the sound speed corresponding to the water temperature under standard atmospheric pressure.

[0044] In step 4, relative standard atmospheric pressure , the sound speed increase is 1.5×10-6 (m / s) / Pa.

[0045] In order to implement the matching method, a ultrasonic transducer acoustic channel length verification calculation system is provided, which is used to execute the above method;

[0046] The system includes a pair of transducers mounted on either side of the flow channel;

[0047] A pair of transducers includes an upstream transducer A and a downstream transducer B; transducer A and transducer B are electrically connected to a timing system respectively, and the timing system is electrically connected to a flow meter host.

[0048] Several measuring points are equidistantly arranged on the sound channel line between transducer A and transducer B; a water temperature meter is installed at each measuring point.

[0049] The present invention uses the sound channel length as the main geometric parameter, which is of great importance to the accuracy of flow measurement. Therefore, by accurately verifying the sound channel length, the accuracy of flow calculation will be further improved, and the ultrasonic flowmeter can better play the role of a high-precision measuring instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is an ultrasonic propagation diagram of the present invention.

[0051] Figure 2 It is a schematic diagram of the non-aqueous medium transmission time measurement principle of the present invention. DETAILED DESCRIPTION

[0052] like Figure 1 , Figure 2 The ultrasonic propagation time method is a method of calculating the flow velocity of each layer based on the forward and reverse propagation time of ultrasonic waves in the fluid. A pair of transducers are installed horizontally on both sides of the flow channel, and the connecting line of the transducers forms a certain angle with the axis direction. (refer to Figure 1 ).

[0053] exist Figure 2 In the simulation experiment, a trapezoidal cross-section river channel is simulated by a static water test tank 3, and transducers A4 and B5 are installed on the static water test tank 3 for matching. Transducer A4 and transducer B5 are respectively connected to the timing system 1 and the flow meter host 2 by circuits, and the timing system 1 is electrically connected to the flow meter host 2.

[0054] A pair of transducers are installed on both sides of the flow channel, and the connecting line of the transducers forms an angle with the axis direction. A pair of transducers is defined as an upstream transducer A and a downstream transducer B; transducer A and transducer B are electrically connected to a timing system, and the timing system is electrically connected to a flow meter host;

[0055] Among them, the propagation time of the ultrasonic wave from the downstream to the upstream transducer is , the propagation time from the upstream to the downstream transducer , due to the axial water velocity Projection on the channel line Due to the influence of the ultrasonic wave propagation process, the two propagation times are different in the same measurement.

[0056] (1);

[0057] Where: ——Voice tract length, m; ——Calculate the speed of sound, m / s; ——projected velocity of the acoustic channel, m / s;

[0058] From formula (1), we can simultaneously obtain the velocity projection in the direction of the sound channel: and calculate the speed of sound ;

[0059] (1.1);

[0060] (1.2);

[0061] The flow meter host measures the signal propagation time through the timing system: the timing starts when a pulse signal is sent from the timing system R_A end. The signal reaches transducer A through the cable, generates an ultrasonic signal, and propagates to transducer B. After transducer B receives the ultrasonic signal, it converts it into an electrical signal, which is then transmitted to the R_B end through the cable. The timing ends. The timing duration is On the contrary, the timing starts when a pulse signal is sent from the timing system R_B. The signal reaches transducer B through the cable, generates an ultrasonic signal, and propagates to A. After receiving the ultrasonic signal, A converts it into an electrical signal, which is then transmitted to R_A through the cable, and the timing ends. The timing duration is .

[0062] From the above description, we can see that: In fact, it includes the propagation time of ultrasound from upstream transducer A to downstream transducer B. , the transmission time of electrical signals in cables and the transmission time of non-aqueous media for conversion of electricity and sound ,like Figure 1 The solid line represents; In fact, it includes the propagation time of ultrasound from the downstream transducer B to the upstream transducer A. , the transmission time of electrical signals in cables and the transmission time of non-aqueous media for conversion of electricity and sound ,like Figure 1 The dotted line indicates .

[0063] The exact :

[0064] Two measurement experiments were conducted in stable water to ensure that the time interval between the two experiments was short and the physical properties of the water medium did not change. The actual measured sound channel lengths during the two measurements were , The two recording times of the flow meter host measurement are and Because the physical properties of the water medium in the two measurements have not changed, the calculated sound velocity c of ultrasound in the water medium has not changed. According to the above description, the following formula can be obtained:

[0065] (2);

[0066] The non-aqueous medium transmission time is derived from the experimental process and conclusions:

[0067] (2.1);

[0068] The non-aqueous medium transmission time is a fixed value, which can be used to correct the actual ultrasonic propagation time in water:

[0069] (3);

[0070] Using the above method, the ultrasonic forward propagation time and reverse propagation time measured by the flow meter host can be calibrated to ensure that , With precise , , the sound channel length of the transducer installed on site can be recalculated according to the following method:

[0071] In a channel with water, after the transducer is placed underwater, the distance between the emitting surfaces of the two transducers in the same channel is the channel length. The calculation can only be done by theoretical calculation and cannot be measured. There is a certain deviation between the theoretical geometric size of the channel and the actual size, and there is also a certain deviation between the design position and the actual position when the transducer is placed underwater from above water. These deviations will lead to errors in the calculated theoretical channel length. In the flow velocity formula, the channel length is directly involved in the calculation, so the error in the flow velocity calculation is directly introduced by the channel length. In order to improve the accuracy of flow velocity measurement, it is an effective method to fundamentally reduce the error of the channel length.

[0072] The sound velocity is calculated from the above ultrasonic propagation process equations: c and vocal tract length L Relationship , according to the current measurement of the flow meter , and preset channel length , the current calculated sound speed can be obtained c When calculating the speed of sound c The current real speed of sound V The inconsistency indicates that the sound speed is calculated incorrectly, and the only reason for the error in calculating the sound speed is that the preset sound channel length value is incorrect.

[0073] Refer to Table 1. Based on the existing measurement regulations, there is a description of the relationship between sound velocity and water temperature. According to the content of the GB / Z 35717-2017 regulations, standard atmospheric pressure (101325Pa), the relationship between the speed of sound and the water temperature is as follows:

[0074] (4);

[0075] In the formula, is the speed of sound affected by water temperature under standard atmospheric pressure (m / s);

[0076] t n = t / 100, t is temperature (℃); coefficient A = 1402.39, B = 1478.5625, C = 0.69494542, D =0.16618854, E = -0.0160586, F = 0.02192692;

[0077] The applicable range of this formula is: temperature (0~90) ℃.

[0078] The present invention uses a high-precision water thermometer, sets no less than 20 temperature measuring points at an average distance on the sound channel line, performs arithmetic averaging on all measuring points to obtain the average water temperature, and substitutes the above formula to obtain the sound velocity corresponding to the water temperature under standard atmospheric pressure;

[0079] In addition, the speed of sound in water increases with increasing pressure, relative to standard atmospheric pressure. (101325Pa), the sound speed increase is 1.5×10-6 (m / s) / Pa.

[0080] Measure the current atmospheric pressure using a standard barometer , then the actual speed of sound ;

[0081] According to the current actual sound speed V , try to make the calculated sound speed equal to or close to the actual sound speed, the method is: use the formula , the exact value of the vocal tract length can be inferred In this way, the length of the sound channel can be verified and the purpose of improving the flow velocity accuracy can be achieved.

[0082] Table 1 Vocal tract length review

[0083]

[0084] The present invention is fully described for a clearer disclosure, and the prior art is not listed one by one.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents; it is obvious for those skilled in the art to combine multiple technical solutions of the present invention. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. The technical contents not described in detail in the present invention are all known technologies.

Claims

1. A method for calculating the length of an ultrasonic transducer sound channel, characterized in that: The method comprises the following steps: Step 1: Install a pair of transducers on both sides of the flow channel, and the connecting line of the transducers forms an angle with the axis direction. A pair of transducers is defined as an upstream transducer A and a downstream transducer B; transducer A and transducer B are electrically connected to a timing system, and the timing system is electrically connected to a flow meter host; The propagation time of the ultrasonic wave from the downstream transducer B to the upstream transducer A is , the propagation time from the upstream transducer A to the downstream transducer B is ; Considering the axial water velocity Projection on the channel line In the same measurement, the propagation time With propagation time The propagation time is different; Step 2: First, during the ultrasonic propagation process, the following set of equations is obtained: (1)； Where: - vocal tract length; — Calculate the speed of sound; —Voice channel projection velocity; Then, the velocity projection in the direction of the sound channel is obtained by formula (1): and calculate the speed of sound ; (1.1)； (1.2)； Secondly, the flow meter host measures the signal propagation time through the timing system, and obtains the timing time from upstream to downstream respectively: The timing from downstream to upstream is : Again, perform parameter analysis and definition. Contains the propagation time of ultrasound from the upstream transducer A to the downstream transducer B The total transmission time of the electrical signal in the cable and the non-aqueous medium transmission time of the electrical and acoustic conversion is ; Contains the propagation time of ultrasound from downstream transducer B to upstream transducer A ; Step 3: To obtain the exact solution: First, conduct at least two measurement experiments in water to ensure that the total time interval between each experiment is less than the set time; Take two measurement experiments, the measured vocal tract lengths are , The two recording times of the flow meter host measurement are and , we get the following formula: (2)； Then, the non-aqueous medium transmission time was deduced based on the experimental process and conclusions. : (2.1)； Based on the non-aqueous medium transmission time as a fixed value, the actual ultrasonic wave propagation time in water is corrected: (3); The ultrasonic forward propagation time and reverse propagation time measured by the flow meter host are calibrated to ensure that , accuracy; Step 4: Based on parameters , , re-calculate the sound path length of transducer A and transducer B installed on site: First, place transducer A and transducer B underwater in a channel with water. Then, based on formula (1.2), according to the current measurement of the flow meter, , and preset channel length , find the current calculated sound speed c ; Secondly, compare and calculate the speed of sound c The current real speed of sound V ; When calculating the speed of sound c The current real speed of sound V Inconsistency indicates that the speed of sound is calculated c There is an error, the reason is the preset channel length value There is an error; Again, at standard atmospheric pressure The relationship between the speed of sound and the water temperature is as follows: (4)； In the formula, is the speed of sound affected by water temperature under standard atmospheric pressure; t n = t / 100, t is the temperature; coefficient A = 1402.39, B = 1478.5625, C = 0.69494542, D =0.16618854, E = -0.0160586, F = 0.02192692; After that, the speed of sound in water increases with increasing pressure; the current atmospheric pressure is measured using a standard barometer , then the actual speed of sound ; Step 5: According to the current actual sound speed V , so that the speed of sound can be calculated Equal to or close to the actual speed of sound V ; Based on the formula , and inversely deduce the exact vocal tract length Channel length Review.

2. The method for calculating the ultrasonic transducer acoustic channel length review according to claim 1, characterized in that: In step 2, first, a pulse signal is sent from the R_A terminal of the timing system to start timing; then, the pulse signal reaches transducer A through the cable, generating an ultrasonic signal; secondly, the ultrasonic signal propagates from transducer A to transducer B; thirdly, transducer B receives the ultrasonic signal and converts it into an electrical signal; Afterwards, the electrical signal is transmitted to the R_B end of the timing system via the cable, and the timing ends. The timing duration is ; On the contrary, a pulse signal is sent from the R_B end of the timing system to start timing. The pulse signal reaches transducer B through the cable, generating an ultrasonic signal, which is transmitted to transducer A. After transducer A receives the ultrasonic signal, it converts the ultrasonic signal into an electrical signal, which is then transmitted to R_A through the cable, and the timing ends. The timing duration is .

3. The method for calculating the ultrasonic transducer acoustic channel length review according to claim 1, characterized in that: The standard for setting the time is: the physical properties of the water medium in the measurement experiment remain unchanged or the change of the physical properties is lower than the set value, and the calculated sound speed c of ultrasound in the water medium does not change or the change is lower than the set value.

4. The method for calculating the ultrasonic transducer acoustic channel length review according to claim 1, characterized in that: The applicable temperature range of formula (4) is 0℃-90℃.

5. The method for calculating the ultrasonic transducer acoustic channel length verification according to claim 1, characterized in that: In step 4, the average water temperature is obtained by taking the arithmetic average of all the measuring points, and then substituted into formula (4) to obtain the sound speed corresponding to the water temperature under standard atmospheric pressure.

6. The method for calculating the ultrasonic transducer acoustic channel length review according to claim 1, characterized in that: In step 4, relative standard atmospheric pressure , the sound speed increase is 1.5×10-6 (m / s) / Pa.

7. An ultrasonic transducer sound channel length verification calculation system, characterized in that: Used to perform the method according to claim 1; The system includes a pair of transducers mounted on either side of the flow channel; A pair of transducers includes an upstream transducer A and a downstream transducer B; transducer A and transducer B are electrically connected to a timing system respectively, and the timing system is electrically connected to a flow meter host.

8. The ultrasonic transducer acoustic channel length verification and calculation system according to claim 7, characterized in that: Several measuring points are equidistantly arranged on the sound channel line between transducer A and transducer B; a water temperature meter is installed at each measuring point; The flow meter host is electrically connected to transducer A and transducer B.

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