A method and system for detecting a three-dimensional temperature field of a structure based on photo-acoustic fusion measurement

Abstract

This invention discloses a method and system for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement, which relates to the field of temperature field measurement technology. This invention achieves the acquisition of the three-dimensional temperature field of a structure through a three-layer technical architecture of "local measurement + data fusion + temperature field reconstruction", realizes non-invasive three-dimensional temperature field measurement of the structure under extreme working conditions, and also reduces the complexity of the equipment.

Description

Technical Field

[0001] This invention relates to the field of temperature field measurement technology, specifically to a method and system for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement, which can be applied to scenarios such as scientific experiments, high-temperature components in aerospace, and high-temperature equipment in industry that require obtaining the three-dimensional temperature distribution inside the structure. Background Technology

[0002] The statements in this section are provided only as background information in connection with this disclosure and may not constitute prior art.

[0003] In industrial production, equipment operation and maintenance, and scientific research, the temperature field distribution inside a structure is a crucial basis for assessing its operational status, ensuring structural safety, and revealing its thermal characteristics. Currently, measurement techniques for structural temperature fields are mainly divided into two categories: contact measurement and non-contact measurement. Both types of techniques have significant limitations in practical applications.

[0004] 1. Contact measurement technologies (such as thermocouples and resistance temperature detectors)

[0005] Currently, contact measurement mainly involves placing a temperature sensing element in contact with a structural surface or internal measuring point, utilizing the material's temperature-physical properties (such as resistance and thermoelectric potential) to achieve temperature measurement. The disadvantages are that it can only acquire temperature values ​​from a single or a small number of discrete measuring points, making it impossible to measure a large-scale continuous temperature field; for high-temperature, high-pressure, or complex structures, installing the temperature sensing element can damage the structure, and the element itself has a temperature limit (the temperature limit of a thermocouple is approximately 2300℃), making it difficult to adapt to extreme operating conditions; furthermore, because it relies on the element's temperature rise for measurement, the response speed is slow, making it unable to capture highly dynamic temperature changes.

[0006] 2. Non-contact measurement technology

[0007] Ultrasonic temperature measurement: Based on the correlation between the propagation speed of ultrasonic waves in a medium and temperature, ultrasonic waves are transmitted and received, and the propagation time of ultrasonic waves (abbreviated as: acoustic time) is collected to invert the temperature distribution of a fixed one-dimensional path inside the structure.

[0008] High-temperature optics: Utilizing the thermal radiation characteristics of high-temperature objects, high-temperature optical imaging equipment captures the radiation signals from the surface of a structure and converts them into the surface temperature distribution.

[0009] Ultrasonic thermometry primarily relies on time-of-sound temperature inversion. However, due to the limitations of the ultrasonic wave propagation path, a single measuring point can only obtain the temperature distribution along one path (one-dimensional). Multiple electromagnetic ultrasonic, piezoelectric ultrasonic, or moving laser ultrasonic measuring points are needed for scanning to achieve three-dimensional temperature field measurement. Using multiple probes leads to complex sensor arrangements, and scanning laser ultrasound cannot perform transient measurements. High-temperature optics, due to limitations in its measurement principle, can only obtain the temperature distribution on the surface of the structure.

[0010] In summary, existing temperature field measurement technologies cannot simultaneously meet the requirements of "three-dimensional continuous and non-invasive" measurement. Especially under extreme conditions, they are unable to provide comprehensive temperature field data support, and there is an urgent need to develop a new three-dimensional structural temperature field measurement method. Summary of the Invention

[0011] The purpose of this invention is to address the problems of structural integrity damage, low temperature resistance upper limit, and limited coverage of non-contact temperature measurement caused by traditional contact internal temperature measurement, as well as the problem that existing ultrasonic measurement requires the arrangement of ultrasonic arrays or the movement of ultrasonic measuring points to obtain the three-dimensional temperature field. This invention provides a method and system for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement. Through a three-layer technical architecture of "local measurement + data fusion + temperature field reconstruction", the three-dimensional temperature field of the structure can be obtained, enabling non-invasive three-dimensional temperature field measurement of the structure under extreme working conditions, while also reducing the complexity of the equipment.

[0012] The technical solution of the present invention is as follows:

[0013] A method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement includes:

[0014] Ultrasonic measurement of the structure under test One-dimensional temperature distribution along the path ;

[0015] The plane of the structure under test is measured using a high-temperature optical method. Two-dimensional temperature distribution in a plane ;

[0016] The problem of reconstructing the three-dimensional temperature field is transformed into an optimization problem based on the three-dimensional heat conduction equation, and an optimization algorithm is used to update the planar heat flux. The target functional J is made to reach a preset error in order to reconstruct the three-dimensional temperature field of the measured structure.

[0017] The objective functional J is the temperature value. exist On a one-dimensional path and Error and in two-dimensional plane Above and The sum of errors.

[0018] Furthermore, the ultrasonic measurement includes:

[0019] In the three-dimensional rectangular coordinate system of the structure under test In the process, a measuring point is selected on the surface of the structure being measured. Laser ultrasound is used to transmit and receive ultrasonic waves at this measurement point, and the ultrasonic waves are collected along the path of the ultrasonic waves in the structure under test. Propagation time of a one-dimensional path And by inverting the relationship between sound time, sound speed, and temperature, we can obtain... One-dimensional temperature distribution along the path ;

[0020] Transmission time The relationship with temperature is as follows:

[0021]

[0022] In the formula: For measuring points The structural thickness at that location, The local propagation speed of ultrasound in a solid;

[0023] One-dimensional temperature distribution Satisfies the one-dimensional transient heat conduction equation without internal heat source:

[0024] Controlling equations:

[0025] Boundary conditions: ,

[0026] Initial conditions:

[0027] In the formula: For density, For specific heat capacity, Thermal conductivity, Measurement points that change over time Heat flow is considered, and the initial structural temperature is assumed to be uniform. ; For temperature, Position in a one-dimensional direction. From 0 to , For time;

[0028] Combining the relationship between ultrasonic wave propagation time and temperature with the one-dimensional transient heat conduction equation, the ultrasonic wave propagation along the measured structure is obtained. Propagation time of a one-dimensional path Solving the boundary heat flow in the master equations Then through the boundary heat flow The one-dimensional temperature distribution is obtained by calculating the one-dimensional transient heat conduction equation. .

[0029] Furthermore, the high-temperature optical method measurement includes:

[0030] Using an industrial camera to focus on the structure under test A plane is used to acquire image information of that plane, and the two-dimensional plane is obtained based on the correlation between the image RGB values ​​and temperature. Two-dimensional temperature distribution .

[0031] Furthermore, it also includes:

[0032] Data preprocessing is required before using the optimization algorithm.

[0033] Furthermore, the data preprocessing includes: outlier removal and coordinate matching.

[0034] Furthermore, the outlier removal includes:

[0035] use The criteria for removing outliers from the acoustic time data obtained by laser ultrasonic measurement and outlier pixel values ​​from the RGB image data acquired by industrial cameras are as follows: This represents the standard deviation of the data.

[0036] Furthermore, the coordinate matching includes:

[0037] Will and Unified to the three-dimensional rectangular coordinate system of the structure under test middle.

[0038] Furthermore, the objective functional J is expressed as follows:

[0039]

[0040] in:

[0041] For the structure under test Length in direction, For the structure under test Length in direction, For the structure under test Length in direction; in Heat flow in a plane Input, with the remaining boundaries assumed to be adiabatic boundaries.

[0042] Furthermore, the optimization algorithm includes:

[0043] Steepest descent method, conjugate gradient method, or particle swarm optimization algorithm.

[0044] This invention also proposes a three-dimensional temperature field detection system for structures based on optical-acoustic fusion measurement, comprising:

[0045] A laser ultrasonic exciter is used to emit a laser to a predetermined measurement point on the surface of the structure under test to excite an ultrasonic signal;

[0046] A laser ultrasonic receiver is used to receive ultrasonic signals fed back from the structure under test and output acoustic time data corresponding to the propagation time of ultrasonic waves along a one-dimensional path in the structure under test.

[0047] A high-temperature optical system, including a color industrial camera, lens and image acquisition terminal, is used to acquire optical image information on a predetermined two-dimensional plane of the structure under test and output RGB image data of that plane.

[0048] The signal processing module, on the one hand, can invert the one-dimensional temperature distribution of a one-dimensional path based on the correlation between sound time, sound speed, and temperature using sound time data. On the other hand, it can obtain the two-dimensional temperature distribution in a two-dimensional plane based on the correlation between the RGB values ​​of the image and temperature. ;

[0049] The data processing module transforms the three-dimensional temperature field reconstruction problem into an optimization problem based on the three-dimensional heat conduction equation, and uses an optimization algorithm to update the planar heat flux. The target functional J is made to reach a preset error in order to reconstruct the three-dimensional temperature field of the measured structure; the target functional J is the temperature value. On a one-dimensional path and The error and its relationship with the two-dimensional plane The sum of errors; the optimization algorithm includes: steepest descent method, conjugate gradient method or particle swarm optimization algorithm.

[0050] This invention, by combining dual-source measurement with temperature field reconstruction, offers the following advantages compared to existing technologies:

[0051] 1. Enhanced measurement range and dimensionality: Breaking through the limitations of existing one-dimensional ultrasonic and local surface temperature measurements, it enables continuous three-dimensional temperature field measurement of the entire structure, with the coverage extended to the three-dimensional coordinate system of the entire structure, solving the problem that "local measurements cannot reflect the entire temperature distribution".

[0052] 2. Improved non-invasiveness and adaptability to operating conditions: Neither laser ultrasound nor optical cameras require contact with the structure being measured, thus avoiding damage to the structural integrity. This makes them suitable for extreme high-temperature conditions such as aero-engines and industrial high-temperature furnaces, solving the problems of poor temperature resistance and strong invasiveness of traditional contact measurement methods. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0054] Figure 1 This is a flowchart of a method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement;

[0055] Figure 2 The heat transfer model of the structure under test;

[0056] Figure 3 This is a block diagram of a structural three-dimensional temperature field detection system based on optical-acoustic fusion measurement. Detailed Implementation

[0057] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0059] Example 1

[0060] Please see Figure 1 A method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement, comprising:

[0061] Ultrasonic measurement of the structure under test One-dimensional temperature distribution along the path ;

[0062] The plane of the structure under test is measured using a high-temperature optical method. Two-dimensional temperature distribution in a plane ,in The variables are fixed; that is, by fixing the measurement coordinates of "one-dimensional path + two-dimensional plane", we ensure that there are overlapping areas between the two types of data, providing a data foundation for subsequent fusion.

[0063] The problem of reconstructing the three-dimensional temperature field is transformed into an optimization problem based on the three-dimensional heat conduction equation, and an optimization algorithm is used to update the planar heat flux. To achieve a preset error in the target functional J, the three-dimensional temperature field of the measured structure is reconstructed; that is... Figure 1 The step shown is "reconstructing a three-dimensional temperature field based on the optimized inversion logic of the heat conduction equation and dual-source data";

[0064] The objective functional J is the temperature value. exist On a one-dimensional path and Error and in two-dimensional plane Above and The sum of errors.

[0065] In this embodiment, specifically, the ultrasonic measurement includes:

[0066] In the three-dimensional rectangular coordinate system of the structure under test In the process, a measuring point is selected on the surface of the structure being measured. Laser ultrasound (non-contact, theoretically with no upper limit on temperature resistance) is used to transmit and receive ultrasonic waves at the measuring point, and the ultrasonic waves are collected along the path of the measured structure. Propagation time of a one-dimensional path And by inverting the relationship between sound time, sound speed, and temperature, we can obtain... One-dimensional temperature distribution along the path ;

[0067] Transmission time The relationship with temperature is as follows:

[0068]

[0069] In the formula: For measuring points The structural thickness at that location, The local propagation speed of ultrasound in a solid, relative to material properties and structural temperature. Regarding this, within a certain temperature range, it can be expressed as , and It is a constant and can be obtained from a pre-calibrated experiment;

[0070] One-dimensional temperature distribution Satisfies the one-dimensional transient heat conduction equation without internal heat source:

[0071] Controlling equations:

[0072] Boundary conditions: ,

[0073] Initial conditions:

[0074] In the formula: For density, For specific heat capacity, Thermal conductivity, Measurement points that change over time Heat flow is considered, and the initial structural temperature is assumed to be uniform. ; For temperature, Position in a one-dimensional direction. From 0 to , For time;

[0075] Combining the relationship between ultrasonic wave propagation time and temperature with the one-dimensional transient heat conduction equation, the ultrasonic wave propagation along the measured structure is obtained. Propagation time of a one-dimensional path Solving the boundary heat flow in the master equations Specific solution methods include: direct methods such as the sequential method, regularization methods such as Tikhonov, and iterative methods such as gradient descent, further refined by boundary heat flow. The one-dimensional temperature distribution is obtained by calculating the one-dimensional transient heat conduction equation. .

[0076] In this embodiment, specifically, the high-temperature optical method measurement includes:

[0077] A high-resolution industrial camera (such as an industrial CCD camera, suitable for non-invasive measurements under extreme high-temperature conditions) is used to focus on the structure under test. A plane is used to acquire image information of that plane, and the two-dimensional plane is obtained based on the correlation between the image RGB values ​​and temperature. Two-dimensional temperature distribution .

[0078] In this embodiment, it should also be noted that the prior art does not have a preprocessing process, and directly using the raw data leads to large inversion errors. The present invention introduces data preprocessing (outlier removal and coordinate matching) to reduce data noise, ensure the consistency of the two types of data, and provide high-quality input for temperature field reconstruction.

[0079] In this embodiment, the data preprocessing specifically includes: outlier removal and coordinate matching.

[0080] In this embodiment, specifically, the outlier removal includes:

[0081] use The criteria for removing outliers from the acoustic time data obtained by laser ultrasonic measurement and outlier pixel values ​​from the RGB image data acquired by industrial cameras are as follows: This represents the standard deviation of the data.

[0082] In this embodiment, specifically, the coordinate matching includes:

[0083] Will and Unified to the three-dimensional rectangular coordinate system of the structure under test In this embodiment, it should be noted that outlier removal, coordinate matching, etc., can be implemented by those skilled in the art based on the description in this application without creative effort, and will not be elaborated here.

[0084] In this embodiment, specifically, the three-dimensional temperature field reconstruction problem is transformed into an optimization problem based on the three-dimensional heat conduction equation, and the heating condition of the measured structure is as follows: Figure 2 As shown, For the structure under test Length in direction, For the structure under test Length in direction, For the structure under test Length in direction; in Heat flow in a plane Input, with the remaining boundaries assumed to be adiabatic. A one-dimensional temperature distribution is known. and two-dimensional temperature distribution Solve for the equivalent thermal boundary This is equivalent to seeking a suitable The process of making the target functional J reach a preset error. In this invention, the target functional J is the temperature value. exist" On a one-dimensional path and "error" and "two-dimensional plane" Above and The sum of the errors is minimized.

[0085] In this embodiment, the target functional J is specifically represented as follows:

[0086]

[0087] In this embodiment, specifically, the optimization algorithm includes:

[0088] Steepest descent, conjugate gradient, or particle swarm optimization (PSO) algorithm; that is, optimization methods such as steepest descent, conjugate gradient, or PSO algorithm can be used to update. Iterate until the error is less than the preset error.

[0089] This invention improves the accuracy of the three-dimensional temperature field by establishing physical constraints (heat conduction equation) and data constraints (dual-source measurement error).

[0090] Please see Figure 3 The present invention also proposes a three-dimensional temperature field detection system for structures based on optical-acoustic fusion measurement, specifically including:

[0091] A laser ultrasonic exciter is used to emit a laser to a predetermined measurement point on the surface of the structure under test to excite an ultrasonic signal;

[0092] A laser ultrasonic receiver is used to receive ultrasonic signals fed back from the structure under test and output acoustic time data corresponding to the propagation time of ultrasonic waves along a one-dimensional path in the structure under test.

[0093] A high-temperature optical system, including a color industrial camera, lens and image acquisition terminal, is used to acquire optical image information on a predetermined two-dimensional plane of the structure under test and output RGB image data of that plane.

[0094] The signal processing module, on the one hand, can invert the one-dimensional temperature distribution of a one-dimensional path based on the correlation between sound time, sound speed, and temperature using sound time data. On the other hand, it can obtain the two-dimensional temperature distribution in a two-dimensional plane based on the correlation between the RGB values ​​of the image and temperature. ;

[0095] The data processing module transforms the three-dimensional temperature field reconstruction problem into an optimization problem based on the three-dimensional heat conduction equation, and uses an optimization algorithm to update the planar heat flux. The target functional J is made to reach a preset error in order to reconstruct the three-dimensional temperature field of the measured structure; the target functional J is the temperature value. On a one-dimensional path and The error and its relationship with the two-dimensional plane The sum of errors; the optimization algorithm includes: steepest descent method, conjugate gradient method or particle swarm optimization algorithm.

[0096] In this embodiment, it should also be noted that the signal processing module also has data preprocessing (outlier removal and coordinate matching) functions.

[0097] In this embodiment, the data preprocessing specifically includes: outlier removal and coordinate matching.

[0098] In this embodiment, specifically, the outlier removal includes:

[0099] use The criteria for removing outliers from the acoustic time data obtained by laser ultrasonic measurement and outlier pixel values ​​from the RGB image data acquired by industrial cameras are as follows: This represents the standard deviation of the data.

[0100] In this embodiment, specifically, the coordinate matching includes:

[0101] Will and Unified to the three-dimensional rectangular coordinate system of the structure under test In this embodiment, it should be noted that outlier removal, coordinate matching, etc., can be implemented by those skilled in the art based on the description in this application without creative effort, and will not be elaborated here.

[0102] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0103] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement, characterized in that, include: Ultrasonic measurement of the structure under test One-dimensional temperature distribution along the path ; High-temperature optical method for measuring the plane of the structure under test Two-dimensional temperature distribution in a plane ; The problem of reconstructing the three-dimensional temperature field is transformed into an optimization problem based on the three-dimensional heat conduction equation, and an optimization algorithm is used to update the planar heat flux. The target functional J is made to reach a preset error in order to reconstruct the three-dimensional temperature field of the measured structure. The objective functional J is the temperature value. exist On a one-dimensional path and Error and in two-dimensional plane Above and The sum of errors; The ultrasonic measurement includes: In the three-dimensional rectangular coordinate system of the structure under test In the process, a measuring point is selected on the surface of the structure being measured. Laser ultrasound is used to transmit and receive ultrasonic waves at this measurement point, and the ultrasonic waves are collected along the path of the ultrasonic waves in the structure under test. Propagation time of a one-dimensional path And by inverting the relationship between sound time, sound speed, and temperature, we can obtain... One-dimensional temperature distribution along the path ; The high-temperature optical method measurement includes: Using an industrial camera to focus on the structure under test A plane is used to acquire image information of that plane, and the two-dimensional plane is obtained based on the correlation between the image RGB values ​​and temperature. Two-dimensional temperature distribution ; The coordinate matching includes: Will and Unified to the three-dimensional rectangular coordinate system of the structure under test middle.

2. The method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement according to claim 1, characterized in that, Transmission time The relationship with temperature is as follows: In the formula: For measuring points The structural thickness at that location, The local propagation speed of ultrasound in a solid; One-dimensional temperature distribution Satisfies the one-dimensional transient heat conduction equation without internal heat source: Controlling equations: Boundary conditions: , Initial conditions: In the formula: For density, For specific heat capacity, Thermal conductivity, Measurement points that change over time Heat flow is considered, and the initial structural temperature is assumed to be uniform. ; For temperature, Position in a one-dimensional direction. From 0 to , For time; Combining the relationship between ultrasonic wave propagation time and temperature with the one-dimensional transient heat conduction equation, the ultrasonic wave propagation along the measured structure is obtained. Propagation time of a one-dimensional path Solving the boundary heat flow in the master equations Then through the boundary heat flow The one-dimensional temperature distribution is obtained by calculating the one-dimensional transient heat conduction equation. .

3. The method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement according to claim 2, characterized in that, Also includes: Data preprocessing is required before using the optimization algorithm.

4. The method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement according to claim 3, characterized in that, The data preprocessing includes: outlier removal and coordinate matching.

5. The method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement according to claim 4, characterized in that, The outlier removal includes: use The criteria for removing outliers from the acoustic time data obtained by laser ultrasonic measurement and outlier pixel values ​​from the RGB image data acquired by industrial cameras are as follows: This represents the standard deviation of the data.

6. The method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement according to claim 1, characterized in that, The objective functional J is expressed as follows: in: For the structure under test Length in direction, For the structure under test Length in direction, For the structure under test Length in direction; in Heat flow in a plane Input, with the remaining boundaries assumed to be adiabatic boundaries.

7. The method for detecting the three-dimensional temperature field of a structure based on optical-acoustic fusion measurement according to claim 1, characterized in that, The optimization algorithm includes: Steepest descent method, conjugate gradient method, or particle swarm optimization algorithm.

8. A structural three-dimensional temperature field detection system based on optical-acoustic fusion measurement, characterized in that, A method for detecting a three-dimensional temperature field of a structure based on optical-acoustic fusion measurement as described in any one of claims 1-7 includes: A laser ultrasonic exciter is used to emit a laser to a predetermined measurement point on the surface of the structure under test to excite an ultrasonic signal; A laser ultrasonic receiver is used to receive ultrasonic signals fed back from the structure under test and output acoustic time data corresponding to the propagation time of ultrasonic waves along a one-dimensional path in the structure under test. A high-temperature optical system, including a color industrial camera, lens and image acquisition terminal, is used to acquire optical image information on a predetermined two-dimensional plane of the structure under test and output RGB image data of that plane. The signal processing module, on the one hand, can invert the one-dimensional temperature distribution of a one-dimensional path based on the correlation between sound time, sound speed, and temperature using sound time data. On the other hand, it can obtain the two-dimensional temperature distribution in a two-dimensional plane based on the correlation between the RGB values ​​of the image and temperature. ; The data processing module transforms the three-dimensional temperature field reconstruction problem into an optimization problem based on the three-dimensional heat conduction equation, and uses an optimization algorithm to update the planar heat flux. The target functional J is made to reach a preset error in order to reconstruct the three-dimensional temperature field of the measured structure; the target functional J is the temperature value. On a one-dimensional path and The error and its relationship with the two-dimensional plane The sum of errors; the optimization algorithm includes: steepest descent method, conjugate gradient method or particle swarm optimization algorithm.

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