Structural shape acoustic imaging measurement method and device under interference of non-uniform laminar flow field

Abstract

The invention discloses a structural shape acoustic imaging measurement method and device under the interference of a non-uniform laminar flow field, and belongs to the technical field of acoustic imaging measurement, and the method comprises the following steps: employing a two-axis acoustic scanning system to a metal housing outside power equipment, transmitting a phase control array signal, obtaining a fan-shaped scanning image of a section of curve reflected by the electric power equipment structure in the metal shell; equidistantly changing positions along the surface of the metal shell to obtain a series of reflection images of the same curve under an acoustic path; and the actual shape and the structure image of the structure are obtained through non-uniform acoustic path reverse demodulation. The acoustic imaging measurement of the structural shape of the electrical equipment in the non-uniform laminar flow field in the metal shell is realized, and the measurement is comprehensive and high in accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic imaging measurement, and in particular to a method and a device for acoustic imaging measurement of a structure shape under the interference of an inhomogeneous laminar flow field. Background Art

[0002] Large-scale power equipment is all contained in closed metal casings. The key components of the equipment are sealed in the metal casings. Their structures and shapes are diverse. During long-term operation, they are prone to structural displacement, sinking, deformation, and even loose components, posing huge safety hazards to the equipment.

[0003] Existing ultrasonic methods can achieve internal structure and shape imaging through metal casings, but the uneven laminar flow field that exists during operation will greatly affect the propagation speed of ultrasonic waves, resulting in inconsistent signal strength of structural shape imaging and errors in position information, affecting the measurement integrity and accuracy.

[0004] The patent document with publication number CN 114518470 A discloses an acoustic imaging detection method for the non-uniform flow velocity field of insulating oil inside a transformer. It uses a distributed array acoustic sensor to detect the frequency offset value of the acoustic signal on different acoustic paths of the transformer, and reversely solves the parameter data to obtain the frequency change value of different areas on the transformer measurement section, and obtains the difference in the flow velocity of the insulating oil. The flow velocity diagram is drawn by expanding the corresponding flow velocity values ​​at different positions of the transformer. The invention uses the ultrasonic Doppler frequency shift effect, through multi-point and multi-angle scanning, and the application of ultrasonic tomography technology with frequency shift as a parameter to realize the flow velocity detection of the non-uniform fluid field inside the transformer, and proposes the measurement and evaluation of the flow velocity of the insulating oil channel at different positions inside the transformer, so as to improve the lean operation and maintenance level of the equipment. However, the invention cannot measure the structural shape of power equipment in a non-uniform laminar flow field inside the metal casing, and cannot solve the above technical problems. Summary of the invention

[0005] In view of this, the present invention aims at the deficiencies of the prior art and provides a method for acoustic imaging measurement of a structure shape under the interference of an inhomogeneous laminar flow field.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field, comprising the following steps: using an acoustic scanning system for the metal shell outside the power equipment, emitting a phased array signal, and obtaining a fan-shaped reflection image of a section of the curve reflected by the power equipment inside the metal shell, and changing the position of the acoustic scanning system equidistantly along the surface of the metal shell to obtain a series of fan-shaped reflection images of the same curve under the changed positions;

[0007] The actual shape and structural image of the structure are obtained by inversely demodulating the uneven acoustic path of the same curved fan-shaped reflection image under a series of acoustic path change positions.

[0008] Furthermore, the method for reverse demodulation of the non-uniform acoustic path is: utilizing the invariant characteristic of the actual physical distance from the line segment to the surface, first converting the scanning range into basic units of constant sound speed, measuring the total deviation of the sound speed on different paths from the preset sound speed, the total sound speed deviation is the joint result of the unit sound speed deviation, and obtaining the actual value of the relevant unit sound speed by performing derivative back projection solution, and obtaining the actual distance between the target point and the probe through the actual value and the sound propagation time, and obtaining the actual shape and position of a curve by point calculation, thereby realizing the measurement of the shape and size of the structure in the non-uniform fluid field.

[0009] Furthermore, the total sound velocity deviation is the measurement method of the joint effect of the unit sound velocity deviations: using the phased array technology of array imaging, setting the sound velocity to V 0 , using the sector scanning mode, the sector image covers m at a time and can also be represented as an arc line within the segment, and the reading distance L from each arc segment to the sensor is measured d , through geometric calculation, we can know the actual distance L s , and the average sound velocity V is obtained p , that is, the distance passed through each unit is different, V p =(L 1 / L s )V 1 +(L 2 / L s )V 2 +(L 3 / L s )V 3 +...+(L w / L s )V w , one imaging can get the average sound speed on m routes, get m sets of equations, scan point by point along the outside, get m×n equations, and m is greater than w.

[0010] Furthermore, the method of solving by performing derivative back projection is: rearranging the fan-shaped reflection imaging data into parallel projection data by Hilbert transform, and the specific steps are as follows:

[0011] In order to describe the rearrangement formula, a virtual structural position parallel to the real structural position is introduced, and P 1 (β, m, n) represents the data on the virtual structure, (m, n) represents the coordinates on the virtual structure; R and β represent the scanning radius and rotation angle respectively;

[0012] In order to describe the rearranged parallel projection data, another virtual structure position is introduced, and the projection data on it is represented by P(θ, t, s); P 1 (β,m,n) and P(θ,t,s) have the following relationship:

[0013]

[0014] P 1 (β,m,n) is rearranged into parallel data P(θ,t,s), and the rearrangement formula is as follows:

[0015]

[0016] An image representing the derivative of the reflected imaging data, represents any point on the PI line. The PI line is a conventional definition in the image reconstruction algorithm, which represents the line segment connecting the two signal sources on the spiral scanning trajectory. If the PI line is in the center plane (s = 0), then

[0017]

[0018] in,

[0019] For an arbitrary projection P(θ,t,s) (s≠0),

[0020] By scanning all the data point by point and summing them up, we get:

[0021]

[0022] in,

[0023] use represents the sound intensity function of the reconstructed unit, get:

[0024]

[0025] in, x' c It is the point on the PI line A way to express x c1 and x c2 represents the two endpoints of this PI line; C is a constant, represents the Hilbert transform.

[0026] Furthermore, a phased array is used to scan the target area to form a direct-reading image of the detection object. Since the physical state distribution law of the detection object in different cross sections is the same, the sound velocity change is superimposed on the direct-reading data to realize the correction of the direct-reading image.

[0027] Furthermore, the acoustic scanning system is a 2-axis acoustic scanning system, which uses a double worm track to perform axial and circumferential rectangular scanning on the outer wall of the metal shell cylinder, and drives the phased array sensor to move and detect on the surface of the workpiece through a clamping device.

[0028] Furthermore, the phased array sensor has a detection frequency range of 2-5 MHz, 32-64 array chips, a chip size of 10.0 mm×1.0 mm, and a chip spacing of 1.0 mm.

[0029] Another object of the present invention is to provide a device for acoustic imaging measurement of a structure shape under the interference of an inhomogeneous laminar flow field, comprising:

[0030] The acoustic scanning system is configured to transmit a phased array signal to the metal casing outside the power equipment, and obtain a fan-shaped reflection image of a section of the curve reflected by the power equipment inside the metal casing, and change the position of the acoustic scanning system equidistantly along the surface of the metal casing to obtain a series of fan-shaped reflection images of the same curve under the changed positions of the acoustic path;

[0031] The reverse demodulation module is configured to perform reverse demodulation of the non-uniform acoustic path on the same curved fan-shaped reflection image under a series of acoustic path change positions to obtain the actual shape and structural image of the structure.

[0032] Furthermore, the acoustic scanning system is a 2-axis acoustic scanning system, which uses a double worm track to perform axial and circumferential rectangular scanning on the outer wall of the metal shell cylinder, and drives the phased array sensor to move and detect on the surface of the workpiece through a clamping device.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention uses an acoustic scanning system to transmit phased array signals to the metal casing of the power equipment, obtains a fan-shaped scanning image of a section of the curve reflected by the power equipment, then changes the position equidistantly along the surface, and measures the reflection image of the same curve under a series of acoustic paths. Through reverse demodulation of the non-uniform acoustic path, the actual shape and structural image of the structure are obtained, thereby realizing the acoustic imaging measurement of the structural shape of the power equipment in the non-uniform laminar flow field in the metal casing, which is comprehensive and accurate.

[0035] The present invention uses a phased array to scan the target area to form a direct-reading image of the detection object, and superimposes the sound velocity change on the direct-reading data to realize the correction of the direct-reading image, improve the measurement accuracy, and ensure the safe operation of the power equipment.

[0036] In addition, the Hilbert transform is used when solving the derivative back projection, which can quickly obtain the actual distance between the target point and the probe. By calculating point by point, the actual shape and position of a curve can be obtained, thereby realizing the measurement of the shape and size of the structure in the inhomogeneous fluid field. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a geometrical schematic diagram of sector scanning in Embodiment 1 of the present invention;

[0038] Figure 2 is a schematic diagram of rearrangement of fan-shaped reflection imaging data in Example 1 of the present invention;

[0039] Figure 3 It is a schematic diagram of the non-central plane projection coordinate system in Example 1 of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention is clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0041] Embodiment 1: A method for acoustic imaging measurement of a structure shape under the interference of an inhomogeneous laminar flow field, comprising the following steps:

[0042] S1. Use an acoustic scanning system to detect the metal casing of the power equipment, emit a phased array signal, and obtain a fan-shaped reflection image of a curve reflected by the power equipment inside the metal casing. Change the position of the acoustic scanning system at equal intervals along the surface of the metal casing to obtain a series of fan-shaped reflection images of the same curve under different positions.

[0043] S2. Through reverse demodulation of the inhomogeneous acoustic path, the actual shape and structural image of the structure are obtained.

[0044] In S2, the method for reverse demodulation of the non-uniform acoustic path is: utilizing the constant characteristic of the actual physical distance from the line segment to the surface, first converting the scanning range into basic units of constant sound speed, measuring the total deviation of the sound speed on different paths from the preset sound speed, the total sound speed deviation is the joint result of the unit sound speed deviation, and obtaining the actual value of the relevant unit sound speed by performing derivative back projection solution, and obtaining the actual distance between the target point and the probe through the actual value and the sound propagation time, and obtaining the actual shape and position of a curve by point calculation, thereby realizing the measurement of the shape and size of the structure in the non-uniform fluid field.

[0045] The total sound velocity deviation is the combined effect of the unit sound velocity deviation. The measurement method is: using the phased array technology of array imaging, setting the sound velocity to V 0 , using the sector scanning mode, the sector image covers m at a time and can also be represented as an arc line within the segment, and the reading distance L from each arc segment to the sensor is measured d , through geometric calculation, we can know the actual distance L s , and the average sound velocity V is obtained p , that is, the distance passed through each unit is different, V p =(L 1 / L s )V 1 +(L 2 / L s )V 2 +(L 3 / L s )V 3 +...+(L w / L s )V w , one imaging can get the average sound speed on m routes, get m sets of equations, scan point by point along the outside, get m×n equations, and m is greater than w.

[0046] The method of solving the problem by performing derivative back projection is: rearranging the fan-shaped reflection imaging data into parallel projection data by Hilbert transformation, and the specific steps are as follows:

[0047] The geometric diagram of 360° sector scanning is as follows: Figure 1 As shown in the figure, β and R represent the rotation angle and the distance from the probe to the rotation axis, respectively. In order to describe the rearrangement formula, a virtual structural position parallel to the real structural position is introduced at the far point of the coordinate system, and P 1 (β,m,n) represents the data on the virtual structure, (m,n) represents the coordinates on the virtual structure. S, R and β represent the probe, scanning radius and rotation angle respectively.

[0048] In order to describe the rearranged parallel projection data, another virtual structure position is introduced, and the projection data on it is represented by P(θ, t, s). Figure 2 It can be seen that P 1 (β,m,n) and P(θ,t,s) have the following relationship:

[0049]

[0050] P 1 (β,m,n) can be rearranged into parallel data P(θ,t,s), and the rearrangement formula is as follows:

[0051]

[0052] An image representing the derivative of the reflected imaging data, represents any point on the PI line. The PI line is a conventional definition in the image reconstruction algorithm, which represents the line segment connecting the two signal sources on the spiral scanning trajectory. If the PI line is in the center plane (s = 0), then

[0053]

[0054] in, For an arbitrary projection P(θ,t,s)(s≠0), A small range of δθ rotation about the axis A rotation of the axis δθ′ is equivalent, and they correspond to an approximately equal arc length, so there is Figure 3 The central axis of rotation is Axis, vector Parallel to the center plane, vector about Tilt, and have P and S represent a structural position and probe, respectively.

[0055] By scanning all the data point by point and summing them up, we get:

[0056]

[0057] in,

[0058] use represents the sound intensity function of the reconstructed unit, get:

[0059]

[0060] in, x' c It is the point on the PI line A way to express x c1 and x c2 represents the two endpoints of this PI line. C is a constant, represents the Hilbert transform.

[0061] The target area is scanned using a phased array to form a direct-reading image of the test object. Because the physical state distribution of the test object in different cross sections is the same, the sound velocity change is superimposed on the direct-reading data to achieve correction of the direct-reading image.

[0062] The 2-axis acoustic scanning system adopts a double worm track to perform axial and circumferential rectangular scanning on the outer wall of the metal shell cylinder, and drives the phased array sensor to move and detect on the surface of the workpiece through a clamping device.

[0063] The phased array sensor has a detection frequency range of 5 MHz, 64 array chips, a chip size of 10.0 mm×1.0 mm, and a chip spacing of 1.0 mm.

[0064] Embodiment 2: A device for acoustic imaging measurement of a structure shape under the interference of an inhomogeneous laminar flow field, comprising:

[0065] The acoustic scanning system is configured to transmit a phased array signal to the metal casing outside the power equipment, and obtain a fan-shaped reflection image of a section of the curve reflected by the power equipment inside the metal casing, and change the position of the acoustic scanning system equidistantly along the surface of the metal casing to obtain a series of fan-shaped reflection images of the same curve under the changed positions of the acoustic path;

[0066] The reverse demodulation module is configured to perform reverse demodulation of the non-uniform acoustic path on the same curved fan-shaped reflection image under a series of acoustic path change positions to obtain the actual shape and structural image of the structure.

[0067] The acoustic scanning system is a 2-axis acoustic scanning system. The 2-axis acoustic scanning system adopts a double worm track to perform axial and circumferential rectangular scanning on the outer wall of the metal shell cylinder, and drives the phased array sensor to move and detect on the surface of the workpiece through a clamping device.

[0068] The method by which the reverse demodulation module performs reverse demodulation of the non-uniform acoustic path on the same curved fan-shaped reflection image under a series of acoustic path change positions is the same as that in Example 1 and will not be repeated here.

[0069] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field, characterized in that: The following steps are involved: An acoustic scanning system is used on the metal casing outside the power equipment to transmit phased array signals and obtain a fan-shaped reflection image of a section of the curve reflected by the power equipment inside the metal casing. The position of the acoustic scanning system is equidistantly changed along the surface of the metal casing to obtain a series of fan-shaped reflection images of the same curve under changed positions. The actual shape and structural image of the structure are obtained by inversely demodulating the uneven acoustic path of the same curved fan-shaped reflection image under a series of acoustic path change positions.

2. The method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field according to claim 1 is characterized in that: The method for reverse demodulation of the non-uniform acoustic path is as follows: utilizing the constant characteristic of the actual physical distance from the line segment to the surface, first converting the scanning range into basic units of constant sound speed, measuring the total deviation of the sound speed on different paths from the preset sound speed, the total sound speed deviation is the joint result of the unit sound speed deviation, and obtaining the actual value of the relevant unit sound speed by performing derivative back projection solution, and obtaining the actual distance between the target point and the probe through the actual value and the sound propagation time, and obtaining the actual shape and position of a curve by point calculation, thereby realizing the measurement of the shape and size of the structure in the non-uniform fluid field.

3. The method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field according to claim 2 is characterized in that: The total sound velocity deviation is the measurement method of the joint effect of the unit sound velocity deviation: using the phased array technology of array imaging, setting the sound velocity to V0, using the sector scanning mode, the sector image once covers m, which can also be represented as an arc line within the segment, and measuring the reading distance L from each arc segment to the sensor d , through geometric calculation, we can know the actual distance L s , and the average sound velocity V is obtained p , that is, the distance passed through each unit is different, V p =(L1 / L s )V1+(L2 / L s )V2+(L3 / L s )V3+...+(L w / L s )V w , one imaging can get the average sound speed on m routes, get m sets of equations, scan point by point along the outside, get m×n equations, and m is greater than w.

4. The method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field according to claim 2 is characterized in that: The method of solving the problem by performing derivative back projection is: rearranging the fan-shaped reflection imaging data into parallel projection data by Hilbert transformation, and the specific steps are as follows: P1(β,m,n) represents the data on the virtual structure, (m,n) represents the coordinates on the virtual structure; R and β represent the scanning radius and rotation angle respectively; The projection data is represented by P(θ, t, s); P1(β, m, n) and P(θ, t, s) have the following relationship: P1(β,m,n) is rearranged into parallel data P(θ,t,s), and the rearrangement formula is as follows: An image representing the derivative of the reflected imaging data, represents any point on the PI line. The PI line is a conventional definition in the image reconstruction algorithm, which represents the line segment connecting the two signal sources on the spiral scanning trajectory. If the PI line is in the center plane (s = 0), then in, For an arbitrary projection P(θ,t,s) (s≠0), By scanning all the data point by point and summing them up, we get: in, use represents the sound intensity function of the reconstructed unit, get: in, x'c is the point on the PI line A way to express x c1 and x c2 represents the two endpoints of this PI line; C is a constant, represents the Hilbert transform.

5. The method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field according to claim 1, characterized in that: The phased array is used to scan the target area to form a direct-reading image of the detection object, and the sound velocity change is superimposed on the direct-reading data to realize the correction of the direct-reading image.

6. The method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field according to claim 1, characterized in that: The acoustic scanning system is a 2-axis acoustic scanning system. The 2-axis acoustic scanning system adopts a double worm track to perform axial and circumferential rectangular scanning on the outer wall of the metal shell cylinder, and drives the phased array sensor to move and detect on the surface of the workpiece through a clamping device.

7. The method for acoustic imaging measurement of structural shape under the interference of non-uniform laminar flow field according to claim 6, characterized in that: The phased array sensor has a detection frequency range of 2-5 MHz, 32-64 array chips, a chip size of 10.0 mm×1.0 mm, and a chip spacing of 1.0 mm.

8. A structural shape acoustic imaging measurement device under the interference of non-uniform laminar flow field, characterized in that: include: The acoustic scanning system is configured to transmit a phased array signal to the metal casing outside the power equipment, and obtain a fan-shaped reflection image of a section of the curve reflected by the power equipment inside the metal casing, and change the position of the acoustic scanning system equidistantly along the surface of the metal casing to obtain a series of fan-shaped reflection images of the same curve under the changed positions of the acoustic path; The reverse demodulation module is configured to perform reverse demodulation of the non-uniform acoustic path on the same curved fan-shaped reflection image under a series of acoustic path change positions to obtain the actual shape and structural image of the structure.

9. The structure shape acoustic imaging measurement device under the interference of non-uniform laminar flow field according to claim 8, characterized in that: The acoustic scanning system is a 2-axis acoustic scanning system. The 2-axis acoustic scanning system adopts a double worm track to perform axial and circumferential rectangular scanning on the outer wall of the metal shell cylinder, and drives the phased array sensor to move and detect on the surface of the workpiece through a clamping device.

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