An arrayed ultrasonic gas flow rate measurement device and method

Abstract

The application relates to an array type ultrasonic gas flow velocity measuring device and method, belonging to the technical field of ultrasonic flow velocity measurement. The device comprises a transmitting ultrasonic sensor, eight receiving ultrasonic sensors, a transmitting module, a multi-channel receiving module, an amplification and filtering module, an AD conversion module, a central processing unit module, a display module and a communication transmission module. The transmitting ultrasonic sensor is located at the top end of a pipeline, and the eight receiving ultrasonic sensors are symmetrically distributed at the bottom end of the pipeline. The ultrasonic signals transmitted by the transmitting ultrasonic sensor and received by the eight receiving ultrasonic sensors can be used to calculate the gas flow velocity in the pipeline. The device has the advantages that the ultrasonic transmitting signals do not need to be processed, the gas flow velocity can be calculated only through the ultrasonic receiving signals, the continuous measurement of the gas flow velocity can be realized, especially when the gas flow velocity changes rapidly, and the precision of the gas flow velocity measurement is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic flow velocity measurement, and in particular relates to an array-type ultrasonic gas flow velocity measuring device and its measurement method. Background Technology

[0002] As a precision measurement instrument, ultrasonic flow meters offer advantages over other types of flow meters, including a wide measurement range, high accuracy, and cost-effectiveness. They are widely used in industries such as oil and gas and water. In recent years, my country's clean energy market demand has continued to expand, including major new gaseous energy sources such as natural gas, biogas, and coalbed methane. Therefore, high-performance gas flow rate measurement devices have also experienced rapid development.

[0003] Existing ultrasonic flow velocity measurement devices are mostly based on the time-of-flight method, which involves two ultrasonic sensors transmitting and receiving ultrasonic signals, measuring the transit time of the ultrasonic waves during the forward and reverse journeys, and then calculating the difference in transit time to obtain flow velocity information. However, both ultrasonic sensors transmit and receive signals intermittently; that is, they cannot receive signals when transmitting and cannot transmit signals when receiving. Therefore, existing methods calculate flow velocity by having the two ultrasonic sensors alternately transmit and receive signals once. This requires assuming that the gas flow velocity remains constant during the alternating transmission and reception of the two ultrasonic sensors, leading to inaccurate measurements when the flow velocity changes. Furthermore, the measurement process requires a threshold-zero-crossing comparison method to detect the ultrasonic signal. Since the detection of the ultrasonic signal depends on the threshold value, the accuracy of the actual ultrasonic transit time is difficult to guarantee when the amplitude of the initial wave of the ultrasonic signal is lower than the detection threshold. In addition, noise from within the system and environmental noise interference can affect the detection of the ultrasonic received signal, ultimately resulting in a large error in the flow velocity measurement. Therefore, the processing of ultrasonic received signals is particularly important. Ultrasonic signal processing circuits require both a high signal-to-noise ratio and a large amplification factor to amplify the weak ultrasonic signals, which poses significant challenges for practical applications. Therefore, a new technological method is urgently needed to solve this problem.

[0004] Existing flow velocity meters are mostly monochannel, which is simple to design but has low measurement accuracy. In practical applications, multichannel arrangements are used to reduce the impact of flow field installation effects on the measurement error of flow velocity meters, but the arrangements vary. This invention discloses an array-type ultrasonic gas flow velocity measurement device and method. The device employs a single-transmitter, multi-receiver ultrasonic sensor array, comprising one transmitting ultrasonic sensor and eight receiving ultrasonic sensors. The eight receiving ultrasonic sensors form an array, symmetrically arranged around the transmitting ultrasonic sensor, thus including more gas flow velocity information in the received signals. The ultrasonic signals received by the eight receiving ultrasonic sensors are then processed, and the gas flow velocity information can be calculated using an array signal processing algorithm. Compared with other methods, this invention has stronger noise suppression capabilities, higher measurement accuracy, and eliminates the need for processing the ultrasonic transmitted signal or measuring the transit time between the transmitting and receiving signals, enabling continuous measurement of gas flow velocity, especially suitable for scenarios with rapidly changing gas flow velocities. Summary of the Invention

[0005] This invention provides an array-type ultrasonic gas velocity measurement device and method to solve the problems of low accuracy, high susceptibility to noise, and discontinuous measurement in existing ultrasonic gas velocity measurements. It adopts a single-transmitter, multi-receiver ultrasonic sensor array and combines it with an array signal processing algorithm to achieve high-precision continuous measurement of gas velocity, thus meeting the actual needs of gas velocity measurement.

[0006] The technical solution adopted in this invention is an array-type ultrasonic gas flow velocity measuring device, comprising an ultrasonic transmitting sensor, an ultrasonic receiving sensor 1, an ultrasonic receiving sensor 2, an ultrasonic receiving sensor 3, an ultrasonic receiving sensor 4, an ultrasonic receiving sensor 5, an ultrasonic receiving sensor 6, an ultrasonic receiving sensor 7, an ultrasonic receiving sensor 8, a transmitting module, a multi-channel receiving module, an amplification and filtering module, an AD conversion module, a central processing unit module, a display module, and a communication transmission module. The ultrasonic transmitting sensor is located at the top of the pipe to provide the ultrasonic transmission signal required for gas flow rate measurement. Eight ultrasonic receiving sensors are symmetrically arranged on both sides of the bottom of the pipe, centered on the transmitting ultrasonic sensor, forming an ultrasonic sensor receiving array to receive ultrasonic signals containing gas flow rate information. The transmitting ultrasonic sensor is connected to the output of the transmitting module, and the input of the transmitting module is connected to the central processing unit (CPU) module. All eight ultrasonic receiving sensors are connected to the input of a multi-channel receiving module, which is connected to the input of an amplification and filtering module. The output of the amplification and filtering module is connected to the input of an analog-to-digital (AD) converter module, and the output of the AD converter module is connected to the CPU module. The CPU module is connected to a display module to display the measured gas flow rate. Simultaneously, the CPU module is connected to a communication transmission module to transmit the final measured gas flow rate.

[0007] The ultrasonic transmitting sensor, receivers 1, 2, 3, 4, 5, 6, 7, and 8 described in this invention are all located on the outer wall of a pipe. The transmitting ultrasonic sensor is located at the top of the pipe, receiver 1 is located on the left side of the bottom end of the pipe, and receiver 8 is located on the right side of the bottom end of the pipe. These three sensors are arranged in an equilateral triangle. The radius of the pipe is R. The distance from the transmitting ultrasonic sensor to receiver 1 is... The distance between the transmitting ultrasonic sensor and the receiving ultrasonic sensor is... Divide the distance between ultrasonic receiving sensor 1 and ultrasonic receiving sensor 8 into four equal parts and create a cross-section of the pipe. Ultrasonic receiving sensor 2 is located behind the first cross-section, at a vertical distance of R / 2 from the bottom of the pipe. Therefore, the distance from ultrasonic receiving sensor 2 to ultrasonic transmitting sensor is... The receiving ultrasonic sensor three is located on the front side of the first section, at a vertical distance of R / 2 from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor three to the transmitting ultrasonic sensor is... The receiving ultrasonic sensor four is located on the rear side of the second section, at a vertical distance R from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor four to the transmitting ultrasonic sensor is... The receiving ultrasonic sensor 5 is located on the front side of the second section, at a vertical distance R from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 5 to the transmitting ultrasonic sensor is... The receiving ultrasonic sensor six is ​​located on the rear side of the third section, at a vertical distance of R / 2 from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor six to the transmitting ultrasonic sensor is... The receiving ultrasonic sensor 7 is located on the front side of the third section, at a vertical distance of R / 2 from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 7 to the transmitting ultrasonic sensor is...

[0008] In this invention, the transmitting ultrasonic sensor is located at point O, the receiving ultrasonic sensor one at point A, the receiving ultrasonic sensor two at point B, the receiving ultrasonic sensor three at point C, the receiving ultrasonic sensor four at point D, the receiving ultrasonic sensor five at point E, the receiving ultrasonic sensor six at point F, the receiving ultrasonic sensor seven at point G, and the receiving ultrasonic sensor eight at point H. P1 represents the perpendicular from point A to the top of the pipe wall, P4 represents the perpendicular from point H to the top of the pipe wall, P2 is located on the axial line of the outer wall of the pipe in the plane of the first section, and P3 is located on the axial line of the outer wall of the pipe in the plane of the third section. Therefore... α1 represents the angle between the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, where α1 = 60° and cosα1 = OP1 / OA = 1 / 2; α2 represents the angle between the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, where α1 = 60° and cosα1 = OP1 / OA = 1 / 2; α3 represents the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, and... α4 represents the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors (line 4) and the top of the pipe, where α4 = 90° and cosα4 = 0; α5 represents the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors (line 5) and the top of the pipe, where α5 = 90° and cosα5 = 0; α6 represents the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors (line 6) and the top of the pipe, where α4 = 90° and cosα5 = 0; α7 represents the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, and... α8 represents the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, and α8 = 120°, cosα8 = -OP4 / OH = -1 / 2.

[0009] An array-type ultrasonic gas velocity measurement method includes the following steps:

[0010] Step 1: After powering on the device, initialize each module;

[0011] Step 2: After initialization, the central processing unit module controls the transmitting module to drive the transmitting ultrasonic sensor to emit ultrasonic signals. At the same time, the central processing unit module controls the multi-channel receiving module to receive the ultrasonic signals received by ultrasonic sensor 1, ultrasonic sensor 2, ultrasonic sensor 3, ultrasonic sensor 4, ultrasonic sensor 5, ultrasonic sensor 6, ultrasonic sensor 7, and ultrasonic sensor 8 respectively.

[0012] Step 3: The multi-channel receiving module sends the received ultrasonic signal to the amplification and filtering module. The amplification and filtering module then sends the amplified and filtered signal to the AD conversion module, and finally to the central processing unit module for storage.

[0013] The flow velocity components in the directions from the transmitting ultrasonic sensor to each receiving ultrasonic sensor are as follows:

[0014] V1=V cosα1=V / 2

[0015] In the formula: V represents the gas flow rate;

[0016] The velocity components in the two directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0017]

[0018] The velocity components in the three directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0019]

[0020] The velocity components in the four directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0021] V4 = 0

[0022] The velocity components in the five directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0023] V5=0

[0024] The velocity components in the six directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0025]

[0026] The flow velocity components in the seven directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0027]

[0028] The velocity components in the eight directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are:

[0029] V8 = V cosα8 = -V / 2;

[0030] Step 4: Based on the distance between each receiving ultrasonic sensor and the transmitting ultrasonic sensor, and the velocity component in the direction from the transmitting ultrasonic sensor to each receiving ultrasonic sensor obtained in Step 3, the propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to each receiving ultrasonic sensor can be calculated.

[0031] Further calculate the delay time when the ultrasonic signal reaches the i-th receiving ultrasonic sensor relative to when it reaches the first receiving ultrasonic sensor.

[0032] Step 5: The signals received by the eight ultrasonic sensors are represented as follows:

[0033]

[0034] The ultrasonic signal delay time τ obtained in step four i Substituting into the above equation, we get:

[0035]

[0036] The above expression can be written in matrix form as follows:

[0037] X(t) = As(t) + N(t)

[0038] In the formula: X(t)=[x1(t),x2(t),…,x8(t)] H This is represented as a matrix for receiving ultrasonic signals. Represented as an array manifold matrix, N(t) = [n1(t), n2(t), ..., n8(t)] H This is represented as the noise matrix added to the received signal, where (·) H The conjugate transpose operation is used to represent a matrix.

[0039] The covariance matrix of the received ultrasonic signal is obtained as follows:

[0040] R X =E[X(t)X H (t)]

[0041] In the formula: E represents the expectation operator;

[0042] For the covariance matrix R of the received ultrasonic signal X By performing eigenvalue decomposition, we can obtain:

[0043]

[0044] In the formula: U S Represented as the signal subspace, ∑ S Represented as a diagonal matrix composed of large eigenvalues, U N Represented as the noise subspace, ∑ N Represented as a diagonal matrix composed of small eigenvalues;

[0045] Since the signal subspace and the noise subspace are orthogonal to each other, the array manifold matrix and the noise subspace are also orthogonal to each other, that is:

[0046] A H U N =0

[0047] Therefore, the gas flow rate can be obtained by the following formula:

[0048]

[0049] Perform a peak search on the above formula, and the flow rate corresponding to the peak value is the gas flow rate value to be measured.

[0050] Step Six: Display the gas flow rate information obtained in Step Five through the display module and output it through the communication transmission module. Then return to Step Two. Repeat this process to obtain the gas flow rate values ​​at different times.

[0051] In step two of this invention, the transmitted signal of the ultrasonic sensor is:

[0052]

[0053] In the formula: u(t) represents the amplitude of the ultrasonic signal, and ω0 represents the angular frequency of the ultrasonic signal. The initial phase of the ultrasonic signal is represented by t, the time variable is represented by e, the natural constant is represented by j, and the imaginary part is represented by j.

[0054] The ultrasonic signals received by ultrasonic sensors 1, 2, 3, 4, 5, 6, 7, and 8 are as follows:

[0055]

[0056] In the formula: τ i n represents the delay time between the arrival of the ultrasonic signal at the i-th receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor. i (t) represents the additional noise in the signal received by the i-th receiving ultrasonic sensor.

[0057] In step four of this invention, the propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0058]

[0059] In the formula: C represents the propagation speed of ultrasound;

[0060] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0061]

[0062] The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0063]

[0064] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0065]

[0066] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0067]

[0068] The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0069]

[0070] The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0071]

[0072] The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is:

[0073]

[0074] In step four of this invention, the delay time between the arrival of the ultrasonic signal at the first receiving ultrasonic sensor and its arrival at the first receiving ultrasonic sensor is τ1 = t1 - t1 = 0, and the delay time between the arrival of the ultrasonic signal at the second receiving ultrasonic sensor and its arrival at the first receiving ultrasonic sensor is... The delay time between the arrival of the ultrasonic signal at the third receiving ultrasonic sensor and its arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the fourth receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the fifth receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 6th receiving ultrasonic sensor and the arrival at the 1st receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 7th receiving ultrasonic sensor and the arrival at the 1st receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 8th receiving ultrasonic sensor and the arrival at the 1st receiving ultrasonic sensor is:

[0075] Advantages and positive effects of the present invention:

[0076] (1) The measurement principle and process are simple, making it easy to implement and apply in engineering.

[0077] Existing ultrasonic flow velocity measurement methods are mostly based on the time-of-flight method, which measures flow velocity by measuring the propagation time of ultrasonic signals between two ultrasonic sensors. This requires the two ultrasonic sensors to be integrated transmitters and receivers, performing measurements by alternating transmission and reception of ultrasonic signals, resulting in a relatively complex measurement process. The array-type ultrasonic gas flow velocity measurement method provided by this invention eliminates the need for alternating signal transmission and reception, and therefore does not require integrated transmitters and receivers. Only one ultrasonic sensor transmits the signal, and eight ultrasonic sensors receive the signals. The gas flow velocity information can be calculated by measuring the signals received by the eight ultrasonic sensors. The measurement principle is clear, the measurement process is simple, and it is easy to implement in engineering and apply.

[0078] (2) It can realize continuous measurement of gas flow rate, and is especially suitable for scenarios where gas flow rate changes rapidly.

[0079] Existing time-of-flight ultrasonic flow velocity measurement devices require two ultrasonic sensors to be integrated transmitter and receiver, necessitating intermittent signal transmission and reception. This means the sensors cannot receive signals while transmitting, and vice versa, requiring a single transmission and reception cycle between the two sensors to calculate the flow velocity. This necessitates the assumption that the gas velocity remains constant during this cycle, leading to inaccuracies when the velocity changes, especially rapidly. The array-type ultrasonic gas flow velocity measurement device provided by this invention features a continuously transmitting ultrasonic sensor and a continuously receiving ultrasonic sensor. The gas flow velocity value can be calculated from the received ultrasonic array signals, enabling continuous measurement of gas flow velocity, particularly suitable for scenarios with rapidly changing gas flow velocities.

[0080] (3) It has strong noise suppression capabilities and high flow velocity measurement accuracy.

[0081] Compared with traditional ultrasonic flow velocity measuring instruments, the measuring device and method provided by this invention significantly improve measurement accuracy. First, the device employs a single-transmitter, multi-receiver ultrasonic sensor array, containing eight receiving ultrasonic sensors, which can acquire eight signals containing flow velocity information, providing more flow velocity information compared to other methods. Second, the method of this invention uses the eight acquired signals to form an array signal, processes it using a high-performance array signal processing algorithm, and then solves for the flow velocity by finding the maximum value. This not only has extremely strong noise suppression capabilities but also extremely high measurement accuracy. Its advantages are particularly evident in harsh environments or under low signal-to-noise ratio conditions. Attached Figure Description

[0082] Figure 1 This is a system schematic diagram of the present invention;

[0083] Figure 2 This is a schematic diagram of the ultrasonic sensor arrangement of the present invention;

[0084] Figure 3 This is a schematic diagram of the spacing between the transmitting and receiving ultrasonic sensors of the present invention;

[0085] Figure 4 This is a schematic diagram of the included angle of the ultrasonic transceiver sensor of the present invention;

[0086] Figure 5 This is a flowchart of the gas flow rate measurement method of the present invention;

[0087] Figure 6 This is a vector decomposition diagram of the gas flow velocity of the present invention;

[0088] Figure 7 This is a schematic diagram of the gas flow velocity components of the present invention;

[0089] Figure 8 This is a graph showing the results of multiple measurements under a fixed gas flow rate condition according to the present invention;

[0090] Figure 9 This is a graph showing the flow velocity measurement results when the gas flow velocity changes according to the present invention;

[0091] Figure 10 This is a comparison chart of the flow velocity measurement errors between the method of this invention and the time difference method. Detailed Implementation

[0092] like Figure 1 As shown, an array-type ultrasonic gas flow rate measuring device includes an ultrasonic transmitting sensor 1, an ultrasonic receiving sensor 1, an ultrasonic receiving sensor 2, an ultrasonic receiving sensor 2, an ultrasonic receiving sensor 3, an ultrasonic receiving sensor 4, an ultrasonic receiving sensor 4, an ultrasonic receiving sensor 5, an ultrasonic receiving sensor 5, an ultrasonic receiving sensor 6, an ultrasonic receiving sensor 6, an ultrasonic receiving sensor 7, an ultrasonic receiving sensor 8, an ultrasonic receiving sensor 9, a transmitting module 10, a multi-channel receiving module 11, an amplification and filtering module 12, an AD conversion module 13, a central processing unit module 14, a display module 15, and a communication transmission module 16. The ultrasonic transmitting sensor 1 is placed at the top of the pipe to provide the ultrasonic transmission signal required for gas flow rate measurement. The eight ultrasonic receiving sensors 2, 3, 4, 5, 6, 7, 8, and 9 are symmetrically arranged at the bottom of the pipe, centered on the ultrasonic transmitting sensor 1. On one side, an ultrasonic sensor receiving array is formed to receive ultrasonic signals containing gas flow rate information. The transmitting ultrasonic sensor 1 is connected to the output of the transmitting module 10, and the input of the transmitting module 10 is connected to the central processing unit module 14. The eight receiving ultrasonic sensors 2, 3, 4, 5, 6, 7, 8, and 9 are all connected to the input of the multi-channel receiving module 11. The multi-channel receiving module 11 is connected to the input of the amplification and filtering module 12. The output of the amplification and filtering module 12 is connected to the input of the AD conversion module 13. The output of the AD conversion module 13 is connected to the central processing unit module 14. The central processing unit module 14 is connected to the display module 15 to display the measured gas flow rate. At the same time, the central processing unit module 14 is connected to the communication transmission module 16 to transmit the final measured gas flow rate.

[0093] like Figure 2 , Figure 3The diagram shows the arrangement and spacing of the ultrasonic sensors. Transmitting ultrasonic sensor 1, and receiving ultrasonic sensors 2, 3, 4, 5, 6, 7, 8, and 9 are all located on the outer wall of the pipe. Transmitting ultrasonic sensor 1 is located at the top of the pipe, receiving ultrasonic sensor 2 is located on the left side of the bottom end, and receiving ultrasonic sensor 9 is located on the right side of the bottom end. They are arranged in an equilateral triangle. The radius of the pipe is R. The distance from transmitting ultrasonic sensor 1 to receiving ultrasonic sensor 2 is... The distance between the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 89 is Divide the distance between ultrasonic receiving sensor 1 (2) and ultrasonic receiving sensor 8 (9) into four equal parts and create a cross-section of the pipe. Ultrasonic receiving sensor 2 (3) is located behind the first cross-section, at a vertical distance of R / 2 from the bottom of the pipe. Then, the distance from ultrasonic receiving sensor 2 (3) to ultrasonic transmitting sensor 1 is... The receiving ultrasonic sensor 34 is located on the front side of the first section, at a vertical distance of R / 2 from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 34 to the transmitting ultrasonic sensor 1 is... The receiving ultrasonic sensor 45 is located on the rear side of the second section, at a vertical distance R from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 45 to the transmitting ultrasonic sensor 1 is... The receiving ultrasonic sensor 56 is located on the front side of the second section, at a vertical distance R from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 56 to the transmitting ultrasonic sensor 1 is... The receiving ultrasonic sensor 67 is located on the rear side of the third section, at a vertical distance of R / 2 from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 67 to the transmitting ultrasonic sensor 1 is... The receiving ultrasonic sensor 78 is located on the front side of the third section, at a vertical distance of R / 2 from the bottom of the pipe horizontal plane. Therefore, the distance from the receiving ultrasonic sensor 78 to the transmitting ultrasonic sensor 1 is...

[0094] like Figure 4The diagram shows the angle between the transmitting and receiving ultrasonic sensors. Assume the transmitting ultrasonic sensor 1 is located at point O, the receiving ultrasonic sensor 2 at point A, the receiving ultrasonic sensor 3 at point B, the receiving ultrasonic sensor 4 at point C, the receiving ultrasonic sensor 5 at point D, the receiving ultrasonic sensor 6 at point E, the receiving ultrasonic sensor 7 at point F, the receiving ultrasonic sensor 8 at point G, and the receiving ultrasonic sensor 9 at point H. P1 represents the perpendicular from point A to the top of the pipe wall, P4 represents the perpendicular from point H to the top of the pipe wall, P2 is located on the axial line of the outer wall of the pipe in the plane of the first section, and P3 is located on the axial line of the outer wall of the pipe in the plane of the third section. Therefore... α1 represents the angle between the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 2 and the top of the pipe, and α1 = 60°, cosα1 = OP1 / OA = 1 / 2; α2 represents the angle between the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 3 and the top of the pipe, and α3 represents the angle between the direction of the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 4 and the top of the pipe. α4 represents the angle between the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 5 and the top of the pipe, where α4 = 90° and cosα4 = 0; α5 represents the angle between the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 6 and the top of the pipe, where α5 = 90° and cosα5 = 0; α6 represents the angle between the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 7 and the top of the pipe, where α4 = 90° and cosα5 = 0; α7 represents the angle between the direction of the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 7 and the top of the pipe, and α8 represents the angle between the direction of the line connecting the transmitting ultrasonic sensor 1 and the receiving ultrasonic sensor 9 and the top of the pipe, and α8 = 120°, cosα8 = -OP4 / OH = -1 / 2.

[0095] like Figure 5 As shown, an array-type ultrasonic gas velocity measurement method includes the following steps:

[0096] Step 1: After powering on the device, initialize each module;

[0097] Step 2: After initialization, the central processing unit module 14 controls the transmitting module 10 to drive the transmitting ultrasonic sensor 1 to transmit ultrasonic signals. At the same time, the central processing unit module 14 controls the multi-channel receiving module 11 to receive the ultrasonic signals received by ultrasonic sensor 1 2, ultrasonic sensor 2 3, ultrasonic sensor 3 4, ultrasonic sensor 4 5, ultrasonic sensor 5 6, ultrasonic sensor 6 7, ultrasonic sensor 7 8, and ultrasonic sensor 8 9 respectively.

[0098] The transmitted signal of ultrasonic sensor 1 is:

[0099]

[0100] In the formula: u(t) represents the amplitude of the ultrasonic signal, and ω0 represents the angular frequency of the ultrasonic signal. The initial phase of the ultrasonic signal is represented by t, the time variable is represented by e, the natural constant is represented by j, and the imaginary part is represented by j.

[0101] The ultrasonic signals received by ultrasonic sensors 1, 2, 3, 4, 5, 6, 7, 8, and 9 are:

[0102]

[0103] In the formula: τ i n represents the delay time between the arrival of the ultrasonic signal at the i-th receiving ultrasonic sensor and the arrival at the i-th receiving ultrasonic sensor (i-2). i (t) represents the additional noise in the signal received by the i-th receiving ultrasonic sensor;

[0104] Step 3: The multi-channel receiving module 11 sends the received ultrasonic signal to the amplification and filtering module 12. The amplification and filtering module 12 sends the amplified and filtered signal to the AD conversion module 13, and then to the central processing unit module 14 for storage.

[0105] according to Figure 6 , Figure 7 The schematic diagram of gas velocity vector decomposition shows the velocity components in the direction from the transmitting ultrasonic sensor 1 to each receiving ultrasonic sensor. The velocity components in the direction from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 2 are:

[0106] V1=Vcosα1=V / 2

[0107] In the formula: V represents the gas flow rate;

[0108] The velocity component in the direction from ultrasonic sensor 1 to ultrasonic sensor 3 is: The velocity components in the direction from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 4 are: The velocity component in the direction from ultrasonic transmitter 1 to ultrasonic receiver 4 is V4 = 0, the velocity component in the direction from ultrasonic transmitter 1 to ultrasonic receiver 5 is V5 = 0, and the velocity component in the direction from ultrasonic transmitter 1 to ultrasonic receiver 6 is... The flow velocity component in the direction from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 8 is: The velocity component in the direction from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 89 is V8=Vcosα8=-V / 2;

[0109] Step 4: Based on the distance between each receiving ultrasonic sensor and the transmitting ultrasonic sensor 1, and the velocity component in the direction from the transmitting ultrasonic sensor 1 to each receiving ultrasonic sensor obtained in Step 3, the propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to each receiving ultrasonic sensor can be calculated; where:

[0110] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 2 is:

[0111]

[0112] In the formula: C represents the propagation speed of ultrasound;

[0113] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 3 is:

[0114]

[0115] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 4 is:

[0116]

[0117] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 5 is:

[0118]

[0119] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 6 is:

[0120]

[0121] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 6 7 is:

[0122]

[0123] The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor 1 to the receiving ultrasonic sensor 8 is:

[0124]

[0125] The propagation time of the ultrasonic wave from the emitting ultrasonic sensor 1 to the receiving ultrasonic sensor 89 is:

[0126]

[0127] Further calculate the delay time when the ultrasonic signal reaches the i-th receiving ultrasonic sensor, relative to the time when it reaches the i-th receiving ultrasonic sensor, where:

[0128] The delay time between the arrival of the ultrasonic signal at the first receiving ultrasonic sensor and its arrival at the second receiving ultrasonic sensor is τ1 = t1 - t1 = 0. The delay time between the arrival of the ultrasonic signal at the second receiving ultrasonic sensor and its arrival at the third receiving ultrasonic sensor is τ1 = t1 - t1 = 0. The delay time between the arrival of the ultrasonic signal at the third receiving ultrasonic sensor and its arrival at the second receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the fourth receiving ultrasonic sensor and its arrival at the second receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 5th receiving ultrasonic sensor and its arrival at the 2nd receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 6th receiving ultrasonic sensor and its arrival at the 2nd receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 7th receiving ultrasonic sensor and its arrival at the 2nd receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 8th receiving ultrasonic sensor and its arrival at the 2nd receiving ultrasonic sensor is:

[0129] Step 5: The signals received by the eight ultrasonic sensors are represented as follows:

[0130]

[0131] The ultrasonic signal delay time τ obtained in step four i Substituting into the above equation, we get:

[0132]

[0133] The above expression can be written in matrix form as follows:

[0134] X(t) = As(t) + N(t)

[0135] In the formula: X(t)=[x1(t),x2(t),…,x8(t)] H This is represented as a matrix for receiving ultrasonic signals. Represented as an array manifold matrix, N(t) = [n1(t), n2(t), ..., n8(t)] H This is represented as the noise matrix added to the received signal, where (·) H The conjugate transpose operation is used to represent a matrix.

[0136] The covariance matrix of the received ultrasonic signal is obtained as follows:

[0137] R X =E[X(t)X H (t)]

[0138] In the formula: E represents the expectation operator;

[0139] For the covariance matrix R of the received ultrasonic signal X By performing eigenvalue decomposition, we can obtain:

[0140]

[0141] In the formula: U S Represented as the signal subspace, Σ S Represented as a diagonal matrix composed of large eigenvalues, U N Represented as the noise subspace, Σ N Represented as a diagonal matrix composed of small eigenvalues;

[0142] Due to the signal subspace U S With noise subspace U N They are mutually orthogonal, so the array manifold matrix A and the noise subspace U are mutually orthogonal. N They are also mutually orthogonal, that is:

[0143] A H U N =0

[0144] Therefore, the gas flow rate can be obtained by the following formula:

[0145]

[0146] Perform a peak search on the above formula, and the flow rate corresponding to the peak value is the gas flow rate value to be measured.

[0147] Step Six: Display the gas flow rate information obtained in Step Five through display module 15 and output it through communication transmission module 16. Then return to Step Two, and repeat this process to obtain the gas flow rate values ​​at different times.

[0148] The present invention will be further illustrated by the following experimental examples.

[0149] Experiment Example 1: Multiple flow rate measurements under a fixed gas flow rate condition.

[0150] The pipe radius R = 50 cm, and the frequency of the emitted ultrasonic signal is 40 kHz. Twenty gas flow velocity measurement experiments were conducted at a gas flow velocity V = 20 m / s. The gas flow velocity measurement results are as follows: Figure 8 As shown. From Figure 8 It can be seen that the measured value is basically consistent with the actual value, and the gas flow rate is basically without deviation, indicating that the method of the present invention can accurately measure the gas flow rate, and the method of the present invention is feasible.

[0151] Experiment Example 2: Flow velocity measurement experiment during gas flow velocity change.

[0152] The gas flow rate was uniformly varied from 0 m / s to 30 m / s, and flow rate measurements were performed at 5 m / s intervals. The gas flow rate measurement results are as follows: Figure 9 As shown. From Figure 9 As can be seen from this, the method of the present invention can still accurately measure the gas flow rate when the gas flow rate changes, and the measured value is basically consistent with the actual value under different gas flow rate conditions, indicating that the method of the present invention can achieve accurate measurement when the gas flow rate changes.

[0153] Experimental Example 3: Comparison and verification experiment between the method of the present invention and existing flow velocity measurement based on time difference method.

[0154] To demonstrate the superiority of the method of this invention in terms of gas velocity measurement accuracy, a comparative analysis was conducted between the method of this invention and an existing gas velocity measurement method based on time difference under different signal-to-noise ratio conditions. The gas velocity was set to 20 m / s, and the signal-to-noise ratio was set from -20 dB to 12 dB. 500 independent measurement experiments were performed at 4 dB intervals, and the gas velocity measurement error curves of the two methods were obtained as follows: Figure 10 As shown. By Figure 10 It can be seen that the velocity measurement error of the method of the present invention is smaller than that of the existing ultrasonic gas velocity measurement method based on time difference under different signal-to-noise ratio conditions, especially under low signal-to-noise ratio conditions, which fully demonstrates that the present invention has higher velocity measurement accuracy and stronger noise suppression capability. This experiment fully demonstrates the superiority of the method of the present invention.

Claims

1. An array-type ultrasonic gas velocity measurement method, employing an array-type ultrasonic gas velocity measurement device, comprising an ultrasonic transmitting sensor, receiving ultrasonic sensors one, two, three, four, five, six, seven, and eight, a transmitting module, a multi-channel receiving module, an amplification and filtering module, an AD conversion module, a central processing unit module, a display module, and a communication transmission module. The ultrasonic transmitting sensor is positioned at the top of the pipe to provide the ultrasonic transmission signal required for gas velocity measurement, and the eight receiving ultrasonic sensors are symmetrically arranged around the ultrasonic transmitting sensor. An ultrasonic sensor receiving array is formed on both sides of the bottom of the central pipe to receive ultrasonic signals containing gas flow velocity information. An ultrasonic transmitting sensor is connected to the output of a transmitting module, the input of which is connected to a central processing unit (CPU) module. Eight ultrasonic receiving sensors are connected to the input of a multi-channel receiving module, which is connected to the input of an amplification and filtering module. The output of the amplification and filtering module is connected to the input of an analog-to-digital (AD) converter module, and the output of the AD converter module is connected to the CPU module. The CPU module is connected to a display module to display the measured gas flow velocity. Simultaneously, the CPU module is connected to a communication transmission module to transmit the final measured gas flow velocity. Its key feature is... Includes the following steps: Step 1: After powering on the device, initialize each module; Step 2: After initialization, the central processing unit module controls the transmitting module to drive the transmitting ultrasonic sensor to emit ultrasonic signals. At the same time, the central processing unit module controls the multi-channel receiving module to receive the ultrasonic signals received by ultrasonic sensor 1, ultrasonic sensor 2, ultrasonic sensor 3, ultrasonic sensor 4, ultrasonic sensor 5, ultrasonic sensor 6, ultrasonic sensor 7, and ultrasonic sensor 8 respectively. Step 3: The multi-channel receiving module sends the received ultrasonic signal to the amplification and filtering module. The amplification and filtering module then sends the amplified and filtered signal to the AD conversion module, and finally to the central processing unit module for storage. The flow velocity components in the directions from the transmitting ultrasonic sensor to each receiving ultrasonic sensor are as follows: ； In the formula: Expressed as gas flow rate; The velocity components in the two directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； The velocity components in the three directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； The velocity components in the four directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； The velocity components in the five directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； The velocity components in the six directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； The flow velocity components in the seven directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； The velocity components in the eight directions from the transmitting ultrasonic sensor to the receiving ultrasonic sensor are: ； Step 4: Based on the distance between each receiving ultrasonic sensor and the transmitting ultrasonic sensor, and the velocity component in the direction from the transmitting ultrasonic sensor to each receiving ultrasonic sensor obtained in Step 3, the propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to each receiving ultrasonic sensor can be calculated. Further calculations of the ultrasonic signal to reach the first The delay time relative to the arrival of the ultrasonic sensor when receiving the ultrasonic sensor; Step 5: The signals received by the eight ultrasonic sensors are represented as follows: ； The ultrasonic signal delay time obtained in step four Substituting into the above equation, we get: ； The above expression can be written in matrix form as follows: ； In the formula: This is represented as a matrix for receiving ultrasonic signals. Represented as an array manifold matrix, Represented as the received signal with added noise matrix, where The conjugate transpose operation is used to represent a matrix. The covariance matrix of the received ultrasonic signal is obtained as follows: ； In the formula: Represents the expectation operator; Covariance matrix of received ultrasonic signals By performing eigenvalue decomposition, we can obtain: ； In the formula: Represented as a signal subspace, Represented as a diagonal matrix composed of large eigenvalues, Represented as a noise subspace, Represented as a diagonal matrix composed of small eigenvalues; Since the signal subspace and the noise subspace are orthogonal to each other, the array manifold matrix and the noise subspace are also orthogonal to each other, that is: ； Therefore, the gas flow rate can be obtained by the following formula: ； Perform a peak search on the above formula, and the flow rate corresponding to the peak value is the gas flow rate value to be measured. Step Six: Display the gas flow rate information obtained in Step Five through the display module and output it through the communication transmission module. Then return to Step Two. Repeat this process to obtain the gas flow rate values ​​at different times.

2. The array-type ultrasonic gas flow velocity measurement method according to claim 1, characterized in that, In step two, the transmission signal of the ultrasonic sensor is: ； In the formula: This is expressed as the amplitude of the ultrasonic signal. This is expressed as the angular frequency of the ultrasonic signal. This represents the initial phase of the ultrasonic signal. Represented as a time variable, Represented as a natural constant, For imaginary units; The ultrasonic signals received by ultrasonic sensors 1, 2, 3, 4, 5, 6, 7, and 8 are as follows: ； In the formula: This indicates that the ultrasonic signal has reached the [number]th [level]. The delay time of receiving ultrasonic sensors relative to receiving ultrasonic sensors one. Indicates the first Additional noise in the signal received by the ultrasonic sensor.

3. The array-type ultrasonic gas velocity measurement method according to claim 1, characterized in that, In step four, the propagation time of the ultrasonic wave from the emitting ultrasonic sensor to the receiving ultrasonic sensor is: ； In the formula: Expressed as the propagation speed of ultrasound; The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: ； The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: ； The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: ； The propagation time of the ultrasonic wave from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: ； The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: ； The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: ； The propagation time of ultrasound from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is: 。 4. The array-type ultrasonic gas velocity measurement method according to claim 1, characterized in that, In step four, the delay time between the arrival of the ultrasonic signal at the first receiving ultrasonic sensor and its arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the second receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the third receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the fourth receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the fifth receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 6th receiving ultrasonic sensor and the arrival at the 1st receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 7th receiving ultrasonic sensor and the arrival at the 1st receiving ultrasonic sensor is: The delay time between the arrival of the ultrasonic signal at the 8th receiving ultrasonic sensor and the arrival at the first receiving ultrasonic sensor is: .

5. The array-type ultrasonic gas velocity measurement method according to claim 1, characterized in that: The transmitting ultrasonic sensor, and receiving ultrasonic sensors one, two, three, four, five, six, seven, and eight are all located on the outer wall of the pipe. The transmitting ultrasonic sensor is located at the top of the pipe, receiving ultrasonic sensor one is located on the left side of the bottom end of the pipe, and receiving ultrasonic sensor eight is located on the right side of the bottom end of the pipe. The three sensors are arranged in an equilateral triangle, and the radius of the pipe is [radius value missing]. The distance from the transmitting ultrasonic sensor to the receiving ultrasonic sensor is... The distance between the transmitting ultrasonic sensor and the receiving ultrasonic sensor is The distance between ultrasonic receiving sensor 1 and ultrasonic receiving sensor 8 is divided into four equal parts, and the pipe is sectioned. Ultrasonic receiving sensor 2 is located behind the first section, at a vertical distance from the bottom of the pipe to the horizontal plane. Then the distance from the receiving ultrasonic sensor two to the transmitting ultrasonic sensor is The ultrasonic sensor three is located on the front side of the first section, at a vertical distance of [missing information] from the bottom of the pipe horizontal plane. Then the distance from the receiving ultrasonic sensor to the transmitting ultrasonic sensor is... The ultrasonic sensor four is located on the rear side of the second profile, at a vertical distance of [missing information - likely a distance in the original text] from the bottom of the pipe horizontal plane. The distance from the receiving ultrasonic sensor to the transmitting ultrasonic sensor is... The ultrasonic sensor five is located on the front side of the second profile, at a vertical distance of [missing information] from the bottom of the pipe horizontal plane. The distance from the receiving ultrasonic sensor to the transmitting ultrasonic sensor is... The ultrasonic sensor six is ​​located on the rear side of the third profile, at a vertical distance of [missing information - likely a distance in meters] from the bottom of the pipe. The distance from the receiving ultrasonic sensor to the transmitting ultrasonic sensor is... The ultrasonic sensor seven is located on the front side of the third section, at a vertical distance of [missing information] from the bottom of the pipe horizontal plane. The distance from the receiving ultrasonic sensor to the transmitting ultrasonic sensor is... .

6. The array-type ultrasonic gas velocity measurement method according to claim 1, characterized in that: The transmitting ultrasonic sensor is located at point O, the receiving ultrasonic sensor one at point A, the receiving ultrasonic sensor two at point B, the receiving ultrasonic sensor three at point C, the receiving ultrasonic sensor four at point D, the receiving ultrasonic sensor five at point E, the receiving ultrasonic sensor six at point F, the receiving ultrasonic sensor seven at point G, and the receiving ultrasonic sensor eight at point H. This is represented by the foot of the perpendicular between point A and the top of the pipe wall. This is represented by the foot of the perpendicular between point H and the top of the pipe wall. The point is located on the axial line of the outer wall of the pipe in the plane of the first profile. The point is located on the axial line of the outer wall of the pipe in the plane of the third section, therefore , , This is represented by the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, and... , ; This is represented by the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe. ; This is represented by the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe. ; This is represented by the angle between the direction of the four lines connecting the transmitting and receiving ultrasonic sensors and the top of the pipe, and... , ; This is represented by the angle between the direction of the line connecting the transmitting and receiving ultrasonic sensors and the top of the pipe. , ; This is represented by the angle between the direction of the six-line connection between the transmitting and receiving ultrasonic sensors and the top of the pipe. ; This is represented by the angle between the direction of the seven-line connection between the transmitting and receiving ultrasonic sensors and the top of the pipe. ; This is represented by the angle between the direction of the eight lines connecting the transmitting and receiving ultrasonic sensors and the top of the pipe. , .

Images