Turbine blade wall thickness ultrasonic measurement method and device and readable storage medium

Abstract

The invention discloses a turbine blade wall thickness ultrasonic measurement method and device and a readable storage medium. Through multi-directional longitudinal wave / transverse wave sound velocity measurement, the elastic constant of the blade is accurately calculated, and accurate and reliable material parameters are provided. The actual orientation, namely the crystal propagation direction, of the ultrasonic propagation direction in the blade crystal is quantified through conversion of a blade coordinate system and a crystal coordinate system. The problem that crystal orientation deviation is neglected in a traditional method is solved, and sound velocity calculation is highly matched with a crystal structure. The phase velocity is calculated based on the crystal propagation direction and the elastic constant, the propagation velocity of ultrasonic waves in the specific crystal orientation can be directly reflected, and errors caused by the crystal orientation difference between the calibration test block and the blade are reduced. And calculating the group velocity, correcting the initial measurement result of the blade wall thickness by using the group velocity, further reducing the error, and finally obtaining the actual wall thickness of the blade. According to the invention, a measurement model of the single crystal turbine blade wall thickness is constructed, errors are reduced based on theoretical calculation, and high-precision measurement of the single crystal turbine blade wall thickness is realized.

Description

Technical Field

[0001] This application relates to the field of nondestructive testing technology, and in particular to a method, apparatus and readable storage medium for ultrasonic measurement of turbine blade wall thickness. Background Technology

[0002] Turbine blades are crucial components of aero-engines, and their wall thickness is an important geometric dimensional indicator used to assess turbine blade quality. Currently, among turbine blade wall thickness measurement methods, ultrasonic thickness measurement has become the mainstream approach due to its speed, simplicity, accuracy, and efficiency.

[0003] In existing technologies, due to the high periodicity and directionality of atomic arrangement in single-crystal blades, the propagation speed of ultrasonic waves depends on the propagation direction. Traditional ultrasonic thickness measurement methods, which are based on the sound velocity of calibration blocks, will produce large errors and cannot meet the requirements of high-precision engineering. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a method, apparatus, and readable storage medium for ultrasonic measurement of turbine blade wall thickness, enabling high-precision measurement of the wall thickness of single-crystal turbine blades.

[0005] This application discloses a method for ultrasonic measurement of turbine blade wall thickness, the method comprising:

[0006] Based on the measured longitudinal and transverse wave velocities of the blade under test in different directions, the elastic constants of the blade under test are calculated.

[0007] The propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested is transformed into the crystal coordinate system to obtain the crystal propagation direction; the blade coordinate system is set based on the geometric direction of the blade to be tested, and the crystal coordinate system is set based on the crystal orientation of the blade to be tested.

[0008] Based on the unit vector of the crystal propagation direction and the elastic constant, the phase velocity of the ultrasonic wave in the blade to be tested is calculated;

[0009] The group velocity is calculated using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle.

[0010] Based on the group velocity, the wall thickness of the blade under test measured by the ultrasonic thickness gauge is corrected to obtain the actual wall thickness.

[0011] Optionally, before calculating the elastic constants of the blade under test based on the measured longitudinal and transverse wave velocities in different directions, the method further includes:

[0012] A first test block with a first crystal orientation and a second test block with a second crystal orientation are prepared; the first test block and the second test block are made of the same material and in the same state as the blade to be tested.

[0013] The first test block and the second test block were used to replace the blade to be tested for measurement.

[0014] Optionally, calculating the elastic constant of the blade to be tested includes:

[0015] The longitudinal wave velocity and transverse wave velocity of the first test block are measured in a direction perpendicular to the first orientation.

[0016] The longitudinal wave velocity of the second test block is measured in a direction perpendicular to the second orientation;

[0017] The elastic constant is calculated based on the longitudinal and transverse wave velocities of the first test block, the longitudinal wave velocities of the second test block, and the density of the blade to be tested.

[0018] Optionally, transforming the propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested to the crystal coordinate system includes:

[0019] Based on the positional relationship between the first orientation, the second orientation and the blade coordinate system, a transformation matrix from the blade coordinate system to the crystal coordinate system is constructed;

[0020] Based on the transformation matrix, the propagation direction is transformed into the crystal coordinate system.

[0021] Optionally, constructing the transformation matrix from the blade coordinate system to the crystal coordinate system based on the positional relationship between the first orientation, the second orientation, and the blade coordinate system includes:

[0022] Obtain the first angle between the projection of the first orientation onto the ZY plane of the blade coordinate system and the first orientation;

[0023] Obtain the second angle between the projection of the first orientation onto the ZX plane of the blade coordinate system and the first orientation;

[0024] Obtain the third angle between the first orientation and the Z-axis of the blade coordinate system;

[0025] Obtain the fourth angle between the second orientation and the X-axis in the XY plane of the blade coordinate system;

[0026] Based on the first included angle, the second included angle, the third included angle, and the fourth included angle, calculate the correspondence between each direction in the crystal coordinate system and each direction in the blade coordinate system;

[0027] The transformation matrix is ​​constructed based on the correspondence.

[0028] Optionally, the step of correcting the wall thickness of the blade under test measured by the ultrasonic thickness gauge based on the group velocity to obtain the actual wall thickness includes:

[0029] Using a calibration test block that is the same material and in the same state as the blade to be tested, the sound velocity of the ultrasonic thickness gauge is adjusted;

[0030] The wall thickness of the blade under test is measured based on the sound velocity to obtain the measured value;

[0031] The actual wall thickness is obtained by correcting the sound speed and the group velocity.

[0032] Optionally, the step of correcting the actual wall thickness based on the sound speed and the group velocity includes:

[0033] The actual wall thickness is obtained by correcting with the following formula:

[0034] ;

[0035] In the formula, H i The actual wall thickness at the i-th measurement point of the blade to be tested. The measured value at the i-th measurement point of the blade to be tested, where v0 is the speed of sound, v i The group velocity is the i-th measurement point of the blade to be tested.

[0036] Optionally, calculating the group velocity using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle includes:

[0037] The group velocity is calculated using the following formula:

[0038] ;

[0039] In the formula, v g Let v be the group velocity. p Let n be the phase velocity, β be the unit vector, β be the propagation direction angle (i.e., the angle between the crystal propagation direction and the first orientation), and τ be the unit vector perpendicular to n.

[0040] Based on the above-mentioned method for ultrasonic measurement of turbine blade wall thickness, this application also discloses an apparatus for ultrasonic measurement of turbine blade wall thickness, including: an elastic constant calculation unit, a conversion unit, a phase velocity calculation unit, a group velocity calculation unit, and a correction unit;

[0041] The elastic constant calculation unit is used to calculate the elastic constant of the blade under test based on the measured longitudinal wave velocity and transverse wave velocity of the blade under test in different directions.

[0042] The conversion unit is used to convert the propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested to the crystal coordinate system to obtain the crystal propagation direction; the blade coordinate system is set based on the geometric direction of the blade to be tested, and the crystal coordinate system is set based on the crystal orientation of the blade to be tested.

[0043] The phase velocity calculation unit is used to calculate the phase velocity of the ultrasonic wave in the blade to be tested based on the unit vector of the crystal propagation direction and the elastic constant.

[0044] The group velocity calculation unit is used to calculate the group velocity using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle.

[0045] The correction unit is used to correct the wall thickness of the blade to be tested measured by the ultrasonic thickness gauge based on the group velocity, so as to obtain the actual wall thickness.

[0046] Optionally, the device further includes:

[0047] The preparation unit is used to prepare a first test block with a first crystal orientation and a second test block with a second crystal orientation; the first test block and the second test block are made of the same material and state as the blade to be tested;

[0048] A replacement unit is used to replace the blade to be tested with the first test block and the second test block for measurement.

[0049] Optionally, the elastic constant calculation unit includes:

[0050] The first measurement subunit is used to measure the longitudinal wave velocity and transverse wave velocity of the first test block in a direction perpendicular to the first orientation.

[0051] The second measurement subunit is used to measure the longitudinal wave velocity of the second test block in a direction perpendicular to the second orientation;

[0052] The elastic constant calculation subunit is used to calculate the elastic constant based on the longitudinal wave velocity and transverse wave velocity of the first test block, the longitudinal wave velocity of the second test block, and the density of the blade to be tested.

[0053] Optionally, the conversion unit includes:

[0054] Construct sub-units to build a transformation matrix from the blade coordinate system to the crystal coordinate system based on the positional relationship between the first orientation, the second orientation and the blade coordinate system;

[0055] A transformation subunit is used to transform the propagation direction to the crystal coordinate system based on the transformation matrix.

[0056] Optionally, the building subunit includes:

[0057] The first acquisition subunit is used to acquire the first angle between the projection of the first orientation in the ZY plane of the blade coordinate system and the first orientation.

[0058] The second acquisition subunit is used to acquire the second included angle between the projection of the first orientation in the ZX plane of the blade coordinate system and the first orientation.

[0059] The third acquisition subunit is used to acquire the third angle between the first orientation and the Z-axis of the blade coordinate system;

[0060] The fourth acquisition subunit is used to acquire the fourth angle between the second orientation and the X-axis in the XY plane of the blade coordinate system;

[0061] The relationship calculation subunit is used to calculate the correspondence between each direction in the crystal coordinate system and each direction in the blade coordinate system based on the first included angle, the second included angle, the third included angle, and the fourth included angle.

[0062] A matrix construction subunit is used to construct the transformation matrix based on the correspondence.

[0063] Optionally, the correction unit includes:

[0064] The adjustment subunit is used to adjust the sound velocity of the ultrasonic thickness gauge using a calibration test block that is the same material and in the same state as the blade to be tested.

[0065] The measurement subunit is used to measure the wall thickness of the blade under test based on the sound velocity to obtain a measurement value.

[0066] A correction subunit is used to correct the actual wall thickness based on the sound speed and the group velocity.

[0067] Optionally, the correction subunit is used for:

[0068] The actual wall thickness is obtained by correcting with the following formula:

[0069] ;

[0070] In the formula, H iThe actual wall thickness at the i-th measurement point of the blade to be tested. The measured value at the i-th measurement point of the blade to be tested, where v0 is the speed of sound, v i The group velocity is the i-th measurement point of the blade to be tested.

[0071] Optionally, the group velocity calculation unit is used for:

[0072] The group velocity is calculated using the following formula:

[0073] ;

[0074] In the formula, v g Let v be the group velocity. p Let n be the phase velocity, β be the unit vector, β be the propagation direction angle (i.e., the angle between the crystal propagation direction and the first orientation), and τ be the unit vector perpendicular to n.

[0075] Based on the above-described method for ultrasonic measurement of turbine blade wall thickness, this application also discloses a readable storage medium for storing computer program instructions, which, when executed by a processor, can implement the steps of the above method.

[0076] This application discloses a method, apparatus, and readable storage medium for ultrasonic measurement of turbine blade wall thickness. By measuring the sound velocities of longitudinal and transverse waves in multiple directions, the elastic constants of the blade are accurately calculated, providing accurate and reliable material parameters for subsequent steps. The transformation between the blade coordinate system and the crystal coordinate system quantifies the actual orientation of the ultrasonic wave propagation direction within the blade crystal, i.e., the crystal propagation direction. This solves the problem of traditional methods neglecting crystal orientation deviation, ensuring a high degree of matching between the sound velocity calculation and the crystal structure. Based on the crystal propagation direction and elastic constants, the phase velocity is calculated, directly reflecting the propagation speed of ultrasonic waves in a specific crystal orientation, reducing errors caused by differences in crystal orientation between the calibration sample and the blade. The group velocity is then calculated and used to correct the initial measurement results of the blade wall thickness, further reducing errors and ultimately obtaining the actual wall thickness of the blade. This application constructs a measurement model for the wall thickness of single-crystal turbine blades, reducing errors based on theoretical calculations and achieving high-precision measurement of the wall thickness of single-crystal turbine blades. Attached Figure Description

[0077] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0078] Figure 1aThis is a flowchart illustrating a method for ultrasonic measurement of turbine blade wall thickness disclosed in an embodiment of this application.

[0079] Figure 1b This is a schematic diagram of the measurement cross-section of a single-crystal high-temperature alloy hollow blade disclosed in an embodiment of this application;

[0080] Figure 1c This is a schematic diagram showing the relationship between the measurement points on the measurement cross section of a single-crystal high-temperature alloy hollow blade and the blade coordinate system and the crystal coordinate system as disclosed in the embodiments of this application.

[0081] Figure 2 This is a flowchart illustrating another method for ultrasonic measurement of turbine blade wall thickness disclosed in an embodiment of this application.

[0082] Figure 3 This is a schematic diagram of the structure of a device for ultrasonic measurement of turbine blade wall thickness disclosed in an embodiment of this application. Detailed Implementation

[0083] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0084] Example 1: This application discloses a method for ultrasonic measurement of turbine blade wall thickness.

[0085] For details, please refer to Figure 1a The method for ultrasonic measurement of turbine blade wall thickness disclosed in this embodiment includes the following steps:

[0086] Step 101: Calculate the elastic constant of the blade under test based on the measured longitudinal wave velocity and transverse wave velocity in different directions.

[0087] In this embodiment, the blade to be tested is a single-crystal hollow blade, specifically a nickel-based single-crystal alloy material. This embodiment uses a nickel-based single-crystal alloy material as an example of the blade to be tested (hereinafter referred to as the blade), and describes the measurement of the blade's wall thickness. The cross-section of the blade is as follows... Figure 1b As shown, there are three measurement sections, labeled as Section I, Section II, and Section III.

[0088] Nickel-based single-crystal alloys have a face-centered cubic structure, and their stiffness matrix contains three independent elastic constants, namely C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C<sub 11 C 12 and C 44In the method of this embodiment, a first test block with a first crystal orientation and a second test block with a second crystal orientation can be prepared first. The first and second test blocks are made of the same material and have the same state as the blade. These two test blocks will be used to replace the blade for subsequent measurements, which facilitates operation and reduces wear on the blade.

[0089] In this embodiment, the longitudinal and transverse wave velocities of the first test block are measured in a direction perpendicular to the first orientation, and the longitudinal wave velocity of the second test block is measured in a direction perpendicular to the second orientation. The elastic constants are calculated based on the longitudinal and transverse wave velocities of the first test block, the longitudinal wave velocity of the second test block, and the density of the blade.

[0090] As an optional method, a first test block and a second test block with a first orientation

[001] and a second orientation

[110] are prepared. The material of both test blocks can be DD6 alloy, and the thickness can be 10 mm. The first test block is taken, and the longitudinal wave velocity v is measured in the direction perpendicular to

[001] . L

[001] and transverse wave sound speed v T

[001] Accordingly, a second test block was taken, and the longitudinal wave velocity v was measured in the direction perpendicular to

[110] . L

[110] Then, the elastic constants are calculated according to the following formulas (1) to (3):

[0091] (1)

[0092] (2)

[0093] (3)

[0094] In the formula, ρ is the density, which can be measured by the displacement method, and will not be elaborated here.

[0095] In the method of this embodiment, ρ is 8.88 g / cm³. 3 For example, C can be calculated. 11 C 12 and C 44 The values ​​are 254.36 GPa, 158.38 GPa, and 132.45 GPa, respectively.

[0096] Step 102: Transform the propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested into the crystal coordinate system to obtain the crystal propagation direction.

[0097] In the method of this embodiment, a blade coordinate system can be first set based on the geometric direction of the blade, and a crystal coordinate system can be set based on the crystal orientation of the blade. Specifically, the blade coordinate system can be defined as a rectangular coordinate system XYZ with the geometric center of the blade as the origin, where the Z-axis is the blade growth direction, and the X and Y axes are located within the cross-section of the blade. The crystal coordinate system can be defined as a rectangular coordinate system xyz with the crystal orientation

[001] of the blade as the z-axis, the crystal orientation

[100] as the x-axis, and the crystal orientation

[010] as the y-axis.

[0098] In this embodiment, when the first and second test blocks replace the blade, a transformation matrix from the blade coordinate system to the crystal coordinate system can be constructed based on the positional relationship between the first orientation, the second orientation, and the blade coordinate system. Specifically, this can involve obtaining the first angle between the projection of the first orientation onto the ZY plane of the blade coordinate system and the first orientation itself; obtaining the second angle between the projection of the first orientation onto the ZX plane of the blade coordinate system and the first orientation itself; obtaining the third angle between the first orientation and the Z-axis of the blade coordinate system; and obtaining the fourth angle between the second orientation and the X-axis in the XY plane of the blade coordinate system. The transformation matrix of the crystal coordinate system relative to the blade coordinate system is then calculated using these four angles.

[0099] As an alternative method, four included angles are obtained using X-ray diffraction based on the first orientation

[001] and the second orientation

[100] . First, the crystal orientation

[001] in the crystal coordinate system, which is the unit vector of the z-axis, is calculated using the following formula:

[0100] (4)

[0101] (5)

[0102] (6)

[0103] In the formula, α1 is the first included angle, α2 is the second included angle, and α3 is the third included angle. z1, z2, and z3 correspond to the components on each axis in the blade coordinate system.

[0104] The crystal orientation

[100] in the crystal coordinate system, which is the unit vector of the x-axis, is then determined by the following formula:

[0105] (7)

[0106] (8)

[0107] (9)

[0108] In the formula, α4 is the fourth included angle. x1, x2, and x3 correspond to the components on each axis in the blade coordinate system.

[0109] The crystal orientation

[010] in the crystal coordinate system, which is the unit vector of the y-axis, is then determined by the following formula:

[0110] (10)

[0111] In the formula, z c =(z1, z2, z3), y c =(y1, y2, y3), x c =(x1, x2, x3). y1, y2, and y3 correspond to the components on each axis of the blade coordinate system.

[0112] Subsequently, the transformation matrix R from the blade coordinate system to the crystal coordinate system is constructed:

[0113] (11)

[0114] As an alternative method, the blade design requires the Z-axis of the blade coordinate system to coincide with the first orientation

[001] , and the X-axis to deviate from the direction of the second orientation

[100] by 43°. However, in reality, due to fluctuations in growth conditions and limitations in control precision, the growth direction of the blade may deviate and twist. According to the blade orientation measurement, the angle between the projection of the first orientation

[001] in the ZY plane and the first orientation

[001] is 2.1°, the angle between the projection of the first orientation

[001] in the ZX plane and the first orientation

[001] is -2.2°, the angle between the first orientation

[001] and the Z-axis is 3.0°, and the angle between the direction of the second orientation

[100] and the X-axis in the XY plane is 45.7°.

[0115] As an alternative method, the relationship between the blade coordinate system and the crystal coordinate system is as follows: Figure 1c As shown in the figure, typical blade locations d1, d2, d3, d4, and d5 were selected as wall thickness measurement points. Based on the blade profile, the angles between the ultrasonic wave direction at each thickness measurement point in the blade coordinate system and the X-axis were obtained, as shown in Table 1.

[0116] Table 1 Angle between the incident direction of ultrasonic waves and the X-axis of the blade coordinate system

[0117]

[0118] In this embodiment, the ultrasonic propagation direction is transformed to the crystal coordinate system based on a transformation matrix. As an optional method, the incident direction of the ultrasonic wave lies in the XY plane of the blade coordinate system, making an angle θ0 with the X-axis. That is, the direction vector d of the ultrasonic wave propagation direction within the blade coordinate system is... leaf for:

[0119] (12)

[0120] By transforming the ultrasonic wave propagation direction from the blade coordinate system to the crystal coordinate system using a transformation matrix, we obtain d. crystal As shown in the following formula:

[0121] (13)

[0122] In the formula, R T d is the transpose of the transformation matrix R. x d y and d z Let x be the components of the ultrasonic wave propagation direction on the x, y, and z axes in the crystal coordinate system.

[0123] Step 103: Calculate the phase velocity of the ultrasonic wave in the blade to be tested based on the unit vector of the crystal propagation direction and the elastic constant.

[0124] Single-crystal blades are anisotropic materials, and the propagation direction of ultrasound, the elastic constants and density of the material, and the phase velocity of the ultrasound can be related through acoustic equations (such as the Christoffel equation). Therefore, in the method of this embodiment, taking the Christoffel equation as an example, the phase velocity can be calculated using the following formula:

[0125] (14)

[0126] In the formula, C ijkl It is the elastic constant tensor, with subscripts i, j, k, l ∈ {1, 2, 3}, representing the x, y, and z directions in the crystal coordinate system. δ ik For the Kronecker function, v p n is the phase velocity. j and n l The unit vector representing the direction of ultrasonic wave propagation in the crystal coordinate system.

[0127] Step 104: Calculate the group velocity using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle.

[0128] In this embodiment, the group velocity is the speed at which wave group energy propagates, and it is also the speed that can be measured during actual detection. The group velocity can be calculated using the phase velocity, the unit vector of the ultrasonic wave propagation direction, and the partial derivative of the phase velocity with respect to the propagation direction angle. As an optional method, taking the first test block as an example instead of the blade, the group velocity can be calculated using the following formula:

[0129] (15)

[0130] In the formula, v g For group velocity, v pLet n be the phase velocity, β be the propagation direction angle (the angle between the crystal propagation direction and the first orientation), and τ be the unit vector perpendicular to n.

[0131] As an alternative method, taking the data in Table 1 as an example, the group velocity of ultrasound in the blade is shown in Table 2:

[0132] Table 2. Group velocity of ultrasonic waves at the measurement point on the blade (unit: m / s)

[0133]

[0134] Step 105: Based on the group velocity, correct the wall thickness of the blade to be tested measured by the ultrasonic thickness gauge to obtain the actual wall thickness.

[0135] In this embodiment, the sound velocity of the ultrasonic thickness gauge is adjusted using a calibration block that is the same material and state as the blade. The blade wall thickness is then measured based on the adjusted sound velocity to obtain the measured value. Alternatively, the sound velocity of the ultrasonic thickness gauge is adjusted based on a calibration block with a crystal orientation of

[001] , resulting in a sound velocity of 5400 m / s, and the blade wall thickness is initially measured using this sound velocity.

[0136] In the method of this embodiment, the measured values ​​at this point are only preliminary results and are not accurate enough. As an optional method, the leaf can be dissected, and the wall thickness at points d1 to d5 can be measured using high-precision calipers. The error between the measured values ​​and the wall thickness measured by the calipers can be calculated, and the results are shown in Table 3.

[0137] Table 3. Errors between measured values ​​and caliper measurements after leaf dissection (unit: mm)

[0138]

[0139] It can be seen that the initial measurement of the blade wall thickness has a large error. The measured values ​​at points d1 to d4 are all too small, while the measured value at d5 is too large. The maximum measurement error can reach -0.22 mm, and the average error is 0.1 mm.

[0140] In the method of this embodiment, in order to improve the measurement accuracy, the measured value can be corrected based on the adjusted sound velocity and the group velocity obtained through the above steps to obtain a more accurate actual wall thickness.

[0141] As an alternative method, the actual wall thickness can be obtained by correction using the following formula:

[0142] (16)

[0143] In the formula, H i Let be the actual wall thickness at the i-th measurement point of the blade. Let v0 be the measured value at the i-th measurement point on the blade, and v_i be the speed of sound. i Let be the group velocity at the i-th measurement point on the blade.

[0144] As an alternative method, the leaf can also be dissected, and the wall thickness at points d1 to d5 can be measured using high-precision calipers. The corrected actual wall thickness is then compared with the caliper measurement after leaf dissection, and the error between the actual wall thickness and the caliper measurement is calculated. The error results are shown in Table 4.

[0145] Table 4. Error between actual wall thickness and caliper measurement after dissecting the blade (unit: mm)

[0146]

[0147] As shown in Table 4, the corrected sound velocity at each measurement point can significantly reduce the ultrasonic measurement error, with a maximum error of only 0.05 mm and an average error of 0.03 mm.

[0148] The method described in this embodiment solves the problems of sound velocity anisotropy and orientation waveform during the production process of blades by using coordinate transformation matrices, Christoffel equations, and group velocity theory. It constructs a high-precision measurement theoretical chain for single-crystal blade wall thickness, which includes "crystal orientation measurement → coordinate system transformation → phase velocity calculation → group velocity correction". It can handle arbitrary crystal orientation offsets, accurately determine the ultrasonic wave propagation direction by transforming the matrix, and quickly complete the high-precision wall thickness measurement of single-crystal blades. It has high reliability and high engineering application value, and provides reliable technical support for the quality control of single-crystal blades.

[0149] Example 2: This application discloses another method for ultrasonic measurement of turbine blade wall thickness. Please refer to [link to relevant documentation]. Figure 2 This embodiment describes the entire process of ultrasonic measurement of turbine blade wall thickness.

[0150] Step 201: Prepare a first test block with a first crystal orientation and a second test block with a second crystal orientation, and use these two test blocks to replace the blade for measurement.

[0151] In the method of this embodiment, the first test block and the second test block are made of the same material and are in the same condition as the blade.

[0152] Step 202: Measure the longitudinal wave velocity and transverse wave velocity of the first test block in a direction perpendicular to the first orientation, and measure the longitudinal wave velocity of the second test block in a direction perpendicular to the second orientation.

[0153] Step 203: Calculate the elastic constants based on the longitudinal and transverse wave velocities of the first test block, the longitudinal wave velocities of the second test block, and the density of the test blocks.

[0154] Step 204: Set up the blade coordinate system based on the geometric orientation of the test block, and set up the crystal coordinate system based on the crystal orientation of the test block.

[0155] Step 205: Obtain the first angle between the projection of the first orientation onto the ZY plane of the blade coordinate system and the first orientation, the second angle between the projection onto the ZX plane of the blade coordinate system and the first orientation, the third angle with the Z axis of the blade coordinate system, and the fourth angle between the second orientation onto the X axis in the XY plane of the blade coordinate system.

[0156] Step 206: Based on the first included angle, the second included angle, the third included angle, and the fourth included angle, calculate the correspondence between the crystal coordinate system and the blade coordinate system.

[0157] Step 207: Construct the transformation matrix based on the correspondence.

[0158] Step 208: Based on the transformation matrix, the propagation direction of the ultrasonic wave in the test block is transformed to the crystal coordinate system to obtain the crystal propagation direction.

[0159] Step 209: Calculate the phase velocity of the ultrasonic wave in the test block based on the crystal propagation direction using the Christoffel equation.

[0160] Step 210: Calculate the group velocity using the phase velocity, the unit vector of the ultrasonic wave propagation direction, and the partial derivative of the phase velocity with respect to the propagation direction angle.

[0161] Step 211: Using a calibration test block that is the same material and in the same condition as the blade, adjust the sound velocity of the ultrasonic thickness gauge.

[0162] Step 212: Measure the wall thickness of the blade based on the adjusted sound velocity to obtain the measured value.

[0163] Step 213: Based on the adjusted sound velocity and group velocity, correct the measured value to obtain the actual wall thickness.

[0164] Based on the ultrasonic measurement method for turbine blade wall thickness disclosed in the above embodiments, this embodiment correspondingly discloses an apparatus for ultrasonic measurement of turbine blade wall thickness. Please refer to... Figure 3 The device for ultrasonic measurement of turbine blade wall thickness includes: an elastic constant calculation unit 301, a conversion unit 302, a phase velocity calculation unit 303, a group velocity calculation unit 304, and a correction unit 305.

[0165] The elastic constant calculation unit 301 is used to calculate the elastic constant of the blade under test based on the measured longitudinal wave velocity and transverse wave velocity of the blade under test in different directions.

[0166] The conversion unit 302 is used to convert the propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested to the crystal coordinate system to obtain the crystal propagation direction; the blade coordinate system is set based on the geometric direction of the blade to be tested, and the crystal coordinate system is set based on the crystal orientation of the blade to be tested.

[0167] The phase velocity calculation unit 303 is used to calculate the phase velocity of the ultrasonic wave in the blade to be tested based on the unit vector of the crystal propagation direction and the elastic constant.

[0168] The group velocity calculation unit 304 is used to calculate the group velocity using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle.

[0169] The correction unit 305 is used to correct the wall thickness of the blade to be tested measured by the ultrasonic thickness gauge based on the group velocity, so as to obtain the actual wall thickness.

[0170] Optionally, the device further includes:

[0171] The preparation unit is used to prepare a first test block with a first crystal orientation and a second test block with a second crystal orientation; the first test block and the second test block are made of the same material and state as the blade to be tested;

[0172] A replacement unit is used to replace the blade to be tested with the first test block and the second test block for measurement.

[0173] Optionally, the elastic constant calculation unit 301 includes:

[0174] The first measurement subunit is used to measure the longitudinal wave velocity and transverse wave velocity of the first test block in a direction perpendicular to the first orientation.

[0175] The second measurement subunit is used to measure the longitudinal wave velocity of the second test block in a direction perpendicular to the second orientation;

[0176] The elastic constant calculation subunit is used to calculate the elastic constant based on the longitudinal wave velocity and transverse wave velocity of the first test block, the longitudinal wave velocity of the second test block, and the density of the blade to be tested.

[0177] Optionally, the conversion unit 302 includes:

[0178] Construct sub-units to build a transformation matrix from the blade coordinate system to the crystal coordinate system based on the positional relationship between the first orientation, the second orientation and the blade coordinate system;

[0179] A transformation subunit is used to transform the propagation direction to the crystal coordinate system based on the transformation matrix.

[0180] Optionally, the building subunit includes:

[0181] The first acquisition subunit is used to acquire the first angle between the projection of the first orientation in the ZY plane of the blade coordinate system and the first orientation.

[0182] The second acquisition subunit is used to acquire the second included angle between the projection of the first orientation in the ZX plane of the blade coordinate system and the first orientation.

[0183] The third acquisition subunit is used to acquire the third angle between the first orientation and the Z-axis of the blade coordinate system;

[0184] The fourth acquisition subunit is used to acquire the fourth angle between the second orientation and the X-axis in the XY plane of the blade coordinate system;

[0185] The relationship calculation subunit is used to calculate the correspondence between each direction in the crystal coordinate system and each direction in the blade coordinate system based on the first included angle, the second included angle, the third included angle, and the fourth included angle.

[0186] A matrix construction subunit is used to construct the transformation matrix based on the correspondence.

[0187] Optionally, the correction unit 305 includes:

[0188] The adjustment subunit is used to adjust the sound velocity of the ultrasonic thickness gauge using a calibration test block that is the same material and in the same state as the blade to be tested.

[0189] The measurement subunit is used to measure the wall thickness of the blade under test based on the sound velocity to obtain a measurement value.

[0190] A correction subunit is used to correct the actual wall thickness based on the sound speed and the group velocity.

[0191] Optionally, the correction subunit is used for:

[0192] The actual wall thickness is obtained by correcting with the following formula:

[0193] ;

[0194] In the formula, H i The actual wall thickness at the i-th measurement point of the blade to be tested. The measured value at the i-th measurement point of the blade to be tested, where v0 is the speed of sound, v i The group velocity is the i-th measurement point of the blade to be tested.

[0195] Optionally, the group velocity calculation unit 304 is used for:

[0196] The group velocity is calculated using the following formula:

[0197] ;

[0198] In the formula, v g Let v be the group velocity. p Let n be the phase velocity, β be the unit vector, β be the propagation direction angle (i.e., the angle between the crystal propagation direction and the first orientation), and τ be the unit vector perpendicular to n.

[0199] Based on the above-described method for ultrasonic measurement of turbine blade wall thickness, this application also discloses a readable storage medium for storing computer program instructions, which, when executed by a processor, can implement the steps of the above method.

[0200] The embodiments in this specification are described in a progressive manner. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant details can be found in the method section.

[0201] It should also be noted that, in this document, relational terms such as "first" and "second" are used only 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.

[0202] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0203] The features described in the embodiments of this specification can be substituted for or combined with each other, so that those skilled in the art can implement or use this application.

[0204] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for ultrasonic measurement of turbine blade wall thickness, characterized in that, include: Based on the measured longitudinal and transverse wave velocities of the blade under test in different directions, the elastic constants of the blade under test are calculated. The propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested is transformed into the crystal coordinate system to obtain the crystal propagation direction; the blade coordinate system is set based on the geometric direction of the blade to be tested, and the crystal coordinate system is set based on the crystal orientation of the blade to be tested. Based on the unit vector of the crystal propagation direction and the elastic constant, the phase velocity of the ultrasonic wave in the blade to be tested is calculated; The group velocity is calculated using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle. Based on the group velocity, the wall thickness of the blade under test measured by the ultrasonic thickness gauge is corrected to obtain the actual wall thickness.

2. The method according to claim 1, characterized in that, Before calculating the elastic constants of the blade under test based on the measured longitudinal and transverse wave velocities in different directions, the method further includes: A first test block with a first crystal orientation and a second test block with a second crystal orientation are prepared; the first test block and the second test block are made of the same material and in the same state as the blade to be tested. The first test block and the second test block were used to replace the blade to be tested for measurement.

3. The method according to claim 2, characterized in that, The calculation of the elastic constant of the blade to be tested includes: The longitudinal wave velocity and transverse wave velocity of the first test block are measured in a direction perpendicular to the first orientation. The longitudinal wave velocity of the second test block is measured in a direction perpendicular to the second orientation; The elastic constant is calculated based on the longitudinal and transverse wave velocities of the first test block, the longitudinal wave velocities of the second test block, and the density of the blade to be tested.

4. The method according to claim 2, characterized in that, The step of transforming the propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested to the crystal coordinate system includes: Based on the positional relationship between the first orientation, the second orientation and the blade coordinate system, a transformation matrix from the blade coordinate system to the crystal coordinate system is constructed; Based on the transformation matrix, the propagation direction is transformed into the crystal coordinate system.

5. The method according to claim 4, characterized in that, The step of constructing a transformation matrix from the blade coordinate system to the crystal coordinate system based on the positional relationship between the first orientation, the second orientation, and the blade coordinate system includes: Obtain the first angle between the projection of the first orientation onto the ZY plane of the blade coordinate system and the first orientation; Obtain the second angle between the projection of the first orientation onto the ZX plane of the blade coordinate system and the first orientation; Obtain the third angle between the first orientation and the Z-axis of the blade coordinate system; Obtain the fourth angle between the second orientation and the X-axis in the XY plane of the blade coordinate system; Based on the first included angle, the second included angle, the third included angle, and the fourth included angle, calculate the correspondence between each direction in the crystal coordinate system and each direction in the blade coordinate system; The transformation matrix is ​​constructed based on the correspondence.

6. The method according to claim 1, characterized in that, The step of correcting the wall thickness of the blade under test measured by the ultrasonic thickness gauge based on the group velocity to obtain the actual wall thickness includes: Using a calibration test block that is the same material and in the same state as the blade to be tested, the sound velocity of the ultrasonic thickness gauge is adjusted; The wall thickness of the blade under test is measured based on the sound velocity to obtain the measured value; The actual wall thickness is obtained by correcting the sound speed and the group velocity.

7. The method according to claim 6, characterized in that, The step of correcting the actual wall thickness based on the sound speed and the group velocity includes: The actual wall thickness is obtained by correcting with the following formula: ； In the formula, H i The actual wall thickness at the i-th measurement point of the blade to be tested. The measured value at the i-th measurement point of the blade to be tested, where v0 is the speed of sound, v i The group velocity is the i-th measurement point of the blade to be tested.

8. The method according to claim 2, characterized in that, The calculation of the group velocity using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle includes: The group velocity is calculated using the following formula: ； In the formula, v g Let v be the group velocity. p Let n be the phase velocity, β be the unit vector, β be the propagation direction angle (i.e., the angle between the crystal propagation direction and the first orientation), and τ be the unit vector perpendicular to n.

9. A device for ultrasonic measurement of turbine blade wall thickness, characterized in that, include: Elastic constant calculation unit, conversion unit, phase velocity calculation unit, group velocity calculation unit, and correction unit; The elastic constant calculation unit is used to calculate the elastic constant of the blade under test based on the measured longitudinal wave velocity and transverse wave velocity of the blade under test in different directions. The conversion unit is used to convert the propagation direction of the ultrasonic wave in the blade coordinate system of the blade to be tested to the crystal coordinate system to obtain the crystal propagation direction; the blade coordinate system is set based on the geometric direction of the blade to be tested, and the crystal coordinate system is set based on the crystal orientation of the blade to be tested. The phase velocity calculation unit is used to calculate the phase velocity of the ultrasonic wave in the blade to be tested based on the unit vector of the crystal propagation direction and the elastic constant. The group velocity calculation unit is used to calculate the group velocity using the phase velocity, the unit vector, and the partial derivative of the phase velocity with respect to the propagation direction angle. The correction unit is used to correct the wall thickness of the blade to be tested measured by the ultrasonic thickness gauge based on the group velocity, so as to obtain the actual wall thickness.

10. A readable storage medium, characterized in that, Used to store computer program instructions, which, when executed by a processor, can implement the steps of the method described in any one of claims 1-8.

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