Gas turbine wheel disc blade root groove array eddy current detection system and method

Abstract

The invention discloses a gas turbine wheel disc blade root groove array eddy current detection system and method, and the system comprises a reference block, and the inner surface of a blade root groove of the reference block is provided with artificial notch grooves with different sizes and orientations; the array eddy current probe and the probe framework are matched with the blade root groove in shape; the stepping device is integrated on the array eddy current probe and is used for driving the probe and recording the scanned distance; and the array eddy current detector is used for exciting the array eddy current probe and recording impedance change. By adjusting the balance of the array eddy current probe on the reference block and calibrating the sensitivity of the array eddy current detection system, the turbine wheel disc blade root groove defect can be effectively detected. According to the method, the problems of low array eddy current detection sensitivity, accuracy and reliability caused by complex groove surface shape, large appearance curvature, poor surface condition, variable defect orientation, unstable probe scanning speed, low defect positioning and quantitative precision and the like of the in-service turbine wheel disc blade root groove are solved.

Description

Technical Field

[0001] The invention belongs to the field of nondestructive testing of gas turbine components, and in particular relates to an eddy current testing system and method for a gas turbine turbine wheel blade root slot array. Background Art

[0002] The turbine blades of a gas turbine are the core components that convert the kinetic energy and thermal energy of the gas into mechanical energy. The turbine blades transfer the mechanical energy obtained to the turbine rotor through the turbine blade root groove. The turbine blade root groove is the only structure that connects the turbine moving blades to the turbine rotor. It plays an extremely critical role, but the working environment is also extremely harsh. During operation, cracks, corrosion pits and other defects are very likely to appear on the turbine blade root groove and the turbine blade assembly surface, which seriously affects its structural integrity and operational safety. Therefore, effective non-destructive testing of the turbine blade root groove is an important means to ensure the safe operation of the gas turbine.

[0003] Traditional penetration testing methods can only detect open cracks on the surface of turbine wheel blade root slots, but cannot detect closed surface cracks and near-surface cracks. Although magnetic particle testing can detect surface and near-surface cracks, its scope of use is limited because turbine wheels are often made of non-ferromagnetic high-temperature alloys. At the same time, due to the complex shape of the assembly surface of the turbine wheel blade root slot, the implementation of defect detection during penetration and magnetic particle testing and the subsequent observation of results will also be affected. Therefore, the array eddy current testing method has become the preferred non-destructive testing method for turbine wheel blade root slots due to its advantages such as large single detection area, simultaneous detection of surface and near-surface defects, and high detection sensitivity.

[0004] However, due to the complex shape of the turbine blade root groove surface and the large curvature of the surface shape at some locations, the detection process is greatly affected by surface conditions such as oil pollution, rust, and roughness, resulting in low sensitivity and reliability of array eddy current detection. At the same time, due to the variability of defect orientation, there are also high requirements for the sensitivity of array eddy current detection in all directions, and the problem of failing to detect defects in certain orientations cannot occur. Summary of the invention

[0005] The purpose of the present invention is to provide a gas turbine turbine impeller blade root slot array eddy current detection system and method, aiming to solve the problems of low sensitivity, accuracy and reliability of array eddy current detection caused by complex groove surface shape, large external curvature, poor surface condition, variable defect orientation, unstable probe scanning speed, low defect positioning and quantitative accuracy of in-service turbine impeller blade root slots.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A gas turbine turbine disc blade root groove array eddy current detection system, comprising a comparison test block, an array eddy current probe, a stepping device and an array eddy current detector; The comparison test block includes a test block base and a groove arranged on the inner surface of the blade root groove of the test block base. The cross-sectional shape and size of the blade root groove on the test block base are the same as the cross-sectional shape of the blade root groove of the turbine wheel to be tested. The array eddy current probe includes a probe frame and an array eddy current coil. The probe frame matches the shape of the blade root slot and is used to be inserted into the blade root slot with a set gap reserved. The array eddy current coil is arranged on the outer surface of the probe frame. The stepping device includes an encoding device and a driving device; the encoding device is integrated on the probe frame, and as the array eddy current probe scans and records the scanned distance, the driving device is used to drive the array eddy current probe to scan along the axial direction of the turbine wheel blade root groove; The array eddy current detector is used to excite the array eddy current probe to generate eddy currents on the turbine blade root groove detection surface, and record the influence of the change of eddy current field intensity caused by the defects of the detection surface on the impedance change of the array eddy current probe, and determine the depth of the defect according to the impedance change. At the same time, the array eddy current detector has C scanning function and CT scanning function.

[0007] A further improvement of the present invention is that a series of artificial grooves of different sizes and orientations are processed on the comparison test block at different cross-sectional positions along the blade root groove.

[0008] A further improvement of the present invention is that the artificial groove is oriented parallel to the axial direction of the blade root groove, perpendicular to the axial direction of the blade root groove or at 45 degrees to the axial direction of the blade root groove; there is at least one through groove in the artificial groove, and the through groove is perpendicular to the axial direction of the blade root groove.

[0009] A further improvement of the present invention is that the length of the artificial groove is 1 mm to 10 mm, the depth of the groove is 0.1 mm to 5 mm, the width of the groove is not greater than 0.15 mm; and the spacing of the artificial grooves is 1 mm to 10 mm.

[0010] A further improvement of the present invention is that an elastic body that fits the shape of the probe frame is attached to the outer periphery of the array eddy current probe frame, and the thickness of the elastic body is greater than the gap between the array eddy current probe frame and the turbine wheel blade root groove.

[0011] A further improvement of the present invention is that the array eddy current coil is arranged along the outer shape of the array eddy current probe skeleton at the interface between the array eddy current probe skeleton and the elastomer, and the length of the array eddy current coil group is not less than half the length of the arc surface of the turbine wheel blade root slot; the array eddy current coil adopts two rows of staggered coils, and each coil can be used as an excitation coil and a receiving coil; the minimum center distance of the array eddy current coil is not greater than 4 times the length of the minimum defect to be detected.

[0012] A further improvement of the present invention is that the encoding device is fixed on the array eddy current probe frame, the encoding device is contacted and positioned with the turbine wheel blade root groove by roller or wire encoding, and is connected to the encoder interface on the array eddy current detector through a cable.

[0013] A further improvement of the present invention is that the driving device drives the probe forward via a roller in contact with the root groove of the turbine wheel disc, and the probe is integrated with the roller encoding device.

[0014] A further improvement of the present invention is that the array eddy current detector has at least 64 array channels and is integrated with a multiplexing module; the amplitude resolution of the eddy current signal of the array eddy current detector is not less than 16 bits.

[0015] A gas turbine turbine disk blade root slot array eddy current detection method, the method is based on a gas turbine turbine disk blade root slot array eddy current detection system, comprising: Slide the array eddy current probe into and place it at the non-grooved position of the blade root groove of the comparison test block, use the array eddy current detector to excite the array eddy current probe to transmit and receive the induced electromagnetic field, and use the array eddy current detector to balance the array eddy current probe coil; The stepping device is used to make the array eddy current probe uniformly scan the blade root groove of the comparison test block along the axial direction of the blade root groove at a set scanning speed, and the groove defects and through grooves are displayed on the C-scan diagram of the array eddy current detector. The angle between the groove signal and the lift-off signal is made vertical by changing the excitation frequency, and then the lift-off signal is adjusted to a horizontal position. At the same time, the C-scan imaging effect of the instrument is observed. Comprehensive adjustments are made to make the impedance diagram and the C-scan image clearly displayed; the groove on the comparison test block is scanned at least 3 times at the selected scanning speed to ensure that the groove defects can be detected each time; after completing the debugging, the detection parameters are saved in the array eddy current detector; During the actual inspection of the turbine impeller blade root groove, the array eddy current probe is stably placed in the turbine impeller blade root groove, the coil is closely fitted to the surface to be inspected, and the scanning speed is kept uniform; the suspected defects found are identified and recorded through the C-scan image and impedance image.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides a gas turbine turbine disc blade root slot array eddy current detection system and method, wherein the comparison test block and a series of artificial grooves and through grooves of different sizes and orientations are used to simulate the groove surface shape of the turbine disc blade root slot and defects of various orientations, and are used to verify the detection sensitivity of defects with different orientations, as well as the coil consistency of the array eddy current probe; the array eddy current probe skeleton is consistent with the blade root slot shape, ensuring the consistency of the lift-off between the array eddy current probe coil and the turbine disc blade root slot detection surface; the array eddy current coil adopts a two-row staggered coil arrangement, ensuring the consistency of the detection sensitivity within the scanning range of the array eddy current probe; the driving device and the encoding device in the stepping device also ensure the stability of the probe scanning speed and the accuracy of defect positioning and quantification during the detection process. The organic integration of the above technical features forms the present invention, which realizes high-sensitivity, high-precision and high-reliability detection of gas turbine disc blade root slot defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of an eddy current detection system for a gas turbine turbine blade root slot array according to the present invention; Figure 2 It is a schematic diagram of the arrangement of an array eddy current coil in a gas turbine turbine disk blade root slot array eddy current detection system of the present invention; Figure 3 It is a schematic diagram of an array eddy current probe in a gas turbine turbine disk blade root slot array eddy current detection system of the present invention; Figure 4 The present invention is a flow chart of a method for detecting eddy currents of a gas turbine turbine disc blade root slot array.

[0018] Description of reference numerals: 1- comparison test block, 11- test block substrate, 12- groove, 2- array eddy current probe, 21- probe frame, 22- array eddy current coil, 23- elastic body, 24- array eddy current coil group; 3- stepping device, 31- encoding device, 32- driving device, 4- array eddy current detector. DETAILED DESCRIPTION

[0019] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0024] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0025] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Example like Figure 1 to Figure 3 As shown, the present invention provides a gas turbine turbine disk blade root groove array eddy current detection system, including a comparison test block 1, an array eddy current probe 2, a stepping device 3 and an array eddy current detector 4.

[0029] The comparison test block 1 includes a test block base 11 and a notch 12 arranged on the inner surface of the blade root groove of the test block base. The cross-sectional shape and size of the blade root groove on the test block base 11 are the same as the cross-sectional shape of the turbine wheel blade root groove to be tested, and the axial length of the blade root groove is set according to actual needs. A series of artificial notches 12 of different sizes and orientations are machined inside the blade root groove of the comparison test block 1 along different cross-sectional positions of the blade root groove to determine the sensitivity and resolution of array eddy current detection.

[0030] The array eddy current probe 2 includes a probe frame 21 and an array eddy current coil 22. The probe frame 21 matches the shape of the blade root slot and can be smoothly inserted into the blade root slot with a set gap reserved. The array eddy current coil 22 is arranged on the outer surface of the probe frame.

[0031] The stepping device 3 includes an encoding device 31 and a driving device 32. The encoding device 31 is integrated on the skeleton of the array eddy current probe 2. As the array eddy current probe 2 scans and records the scanned distance, the driving device 32 is used to drive the probe to scan along the axial direction of the turbine wheel blade root groove. Preferably, the driving device 32 can be automatically driven.

[0032] The array eddy current detector 4 is used to excite the array eddy current probe to generate eddy currents on the detection surface of the turbine wheel blade root groove, and record the influence of the change in eddy current field intensity caused by the defect on the detection surface on the impedance change of the array eddy current probe, and determine the depth of the defect according to the impedance change; at the same time, the array eddy current detector 4 has a C-scan function and a CT scanning function, which can obtain information such as the length, position and orientation of the defect based on the C-scan image.

[0033] In some embodiments, the comparison block 1 is processed with a series of artificial grooves 12 of different sizes and orientations along different cross-sectional positions of the blade root groove to verify the detection sensitivity, resolution and array element consistency of the array eddy current probe.

[0034] Preferably, the orientation of the artificial groove 12 is generally parallel to the axial direction of the blade root groove, perpendicular to the axial direction of the blade root groove, and at 45° to the axial direction of the blade root groove, which is used to verify the detection sensitivity of the array eddy current probe to defects in different orientations.

[0035] Preferably, the length of the artificial groove 12 is 1 mm to 10 mm, the groove depth is 0.1 mm to 5 mm, and the groove width is not greater than 0.15 mm, which is used to simulate the size of an actual crack and test the sensitivity of the array eddy current detection.

[0036] Preferably, the spacing between the artificial grooves 12 is 1 mm to 10 mm, which is used to verify the resolution of the array eddy current probe.

[0037] In some embodiments, the artificial groove 12 has at least one through groove, which is perpendicular to the axial direction of the blade root groove and is used to verify the consistency of the array elements of the array eddy current probe.

[0038] In some embodiments, the base material, heat treatment state, and processing method of the comparison test block 1 are the same or similar to those of the blade root groove of the turbine disc being tested, and the inner surface roughness of the blade root groove of the comparison test block 1 is consistent with that of the blade root groove of the turbine disc being tested, ensuring that the detection parameters obtained after adjustment on the comparison test block are consistent with the sensitivity and accuracy calibrated on the comparison test block during actual detection.

[0039] In some embodiments, an elastic body 23 that fits the shape of the array eddy current probe skeleton 21 is attached to the outer circumference of the array eddy current probe skeleton 21, and the thickness of the elastic body 23 is greater than the gap between the array eddy current probe skeleton 21 and the turbine wheel blade root groove, and is generally not greater than 1.5 mm. While the array eddy current probe skeleton 21 is stably assembled into the turbine wheel blade root groove, the detection sensitivity of the array eddy current probe 2 will not be seriously reduced.

[0040] In some embodiments, the array eddy current coil 22 is arranged along the outer shape of the array eddy current probe skeleton 21 at the interface between the array eddy current probe skeleton 21 and the elastomer 23, and the length of the array eddy current coil group 24 is not less than half the length of the arc surface of the turbine wheel blade root slot; the array eddy current coil 22 adopts two rows of staggered coils, and each coil can be used as an excitation coil and a receiving coil, forming eddy current fields in different directions between the excitation and receiving coils, thereby realizing effective detection of surfaces and near-surface defects in different orientations and accurate identification of the defect extension direction.

[0041] Preferably, the minimum center distance of the array eddy current coils 22 is no greater than 4 times the length of the minimum defect to be detected, so as to ensure the minimum defect detection capability and defect resolution.

[0042] In some embodiments, the encoding device 31 is fixed on the array eddy current probe skeleton 21. The encoding device 31 is contacted and positioned with the turbine wheel blade root groove by roller or wire encoding. The other end is connected to the encoder interface on the array eddy current detector 4 through a cable to determine the position and size of the detected defect.

[0043] In some embodiments, the driving device 32 can drive the probe forward via a roller that contacts the root groove of the turbine wheel blade, and can also be integrated with a roller encoding device to ensure the stability of the scanning speed during the scanning process of the array eddy current probe.

[0044] Preferably, the driving device 32 is composed of two roller motors, which are in contact with the inner surface of the turbine wheel blade root groove, and rely on the friction between the roller motor wheel and the inner surface to drive the array eddy current probe 2 to scan along the axial direction of the turbine wheel blade root groove. In some embodiments, the array eddy current detector 4 should have at least 64 array channels and integrate a multiplexing module to ensure the coverage area of ​​the array eddy current probe coil group 24 in one scan, thereby reducing the requirement on the number of hardware channels of the array eddy current detector 4 .

[0045] Preferably, the amplitude resolution of the eddy current signal of the array eddy current detector 4 should not be less than 16 bits, thereby ensuring the accuracy of the array eddy current detection data.

[0046] Example 2 like Figure 4 As shown, the present invention provides a method for detecting eddy current of a gas turbine turbine blade root slot array, comprising the following steps: Step S1: slide the array eddy current probe 2 into and place it at the non-grooved position of the blade root groove of the comparison test block 1, use the array eddy current detector 4 to excite the array eddy current probe 2 to transmit and receive the induced electromagnetic field, and use the array eddy current detector 4 to balance the array eddy current coil 22.

[0047] Step S2: Use the stepping device 3 to make the array eddy current probe 2 uniformly scan the blade root groove of the comparison test block 1 along the axial direction of the blade root groove at the set scanning speed, and display the groove 12 and the through groove 12 on the C-scan diagram of the array eddy current detector 4. By changing the excitation frequency, etc., the angle between the groove 12 signal and the lift-off signal is made as vertical as possible, and then the lift-off signal is adjusted to a horizontal position. At the same time, the C-scan imaging effect of the array eddy current detector 4 is observed, and the comprehensive adjustment is made so that both the impedance diagram and the C-scan image are clearly displayed. Scan the groove 12 on the comparison test block 1 at least 3 times at the selected scanning speed to ensure that the groove 12 can be detected each time. After the debugging is completed, save the detection parameters in the array eddy current detector 4.

[0048] Step S3: When actually testing the turbine wheel blade root groove, the array eddy current probe 2 should be stably placed in the turbine wheel blade root groove, so that the coil 22 fits tightly with the surface to be tested, and the scanning speed is kept uniform. The suspected defects found are identified and recorded through the C-scan image and impedance image. In order to reduce the interference caused by the edge effect of eddy current detection, high-pass filtering is preferably used to suppress interference signals during detection.

[0049] Example 3 1. Preparation of comparison test blocks The blade root groove of the turbine wheel of the 9FA gas engine is taken as the test object, and a comparison test block matrix 11 is prepared to ensure that the cross-sectional shape and size of the comparison test block 1 are the same as those of the blade root groove of the turbine wheel to be tested, and the axial length of the comparison test block 1 is not less than 200 mm.

[0050] A series of artificial grooves 12 of different sizes and orientations are processed on the inner surface of the blade root groove of the comparison test block base 11. The orientation of the artificial grooves 12 is parallel to the axial direction of the blade root groove, perpendicular to the axial direction of the blade root groove, and 45° to the axial direction of the blade root groove. The length is 5mm, the depth is 0.2mm, the width is 0.15mm, and the spacing is 10mm. At the same time, a through groove perpendicular to the axial direction is processed at a distance of 50mm from one end of the comparison test block 1.

[0051] 2. Design of array eddy current probe The probe frame 21 is designed to match the shape of the blade root groove of the turbine wheel of the 9FA gas engine, and a 1mm gap is reserved.

[0052] An array of eddy current coils 22 is arranged on the outer surface of the probe skeleton 21, and an elastic body 23 is arranged on the periphery. The thickness of the elastic body 23 is greater than 1 mm and less than 1.5 mm.

[0053] The length of the array eddy current coil group 24 is not less than 100 mm, and the coils are arranged in two rows in a staggered manner, with a coil center distance of 3 mm.

[0054] 3. Design the stepping device The encoding device 31 is integrated on the array eddy current probe skeleton 21, and is contacted and positioned with the turbine wheel blade root groove by roller or wire encoding. The other end is connected to the encoder interface on the array eddy current detector 4 through a cable.

[0055] The driving device 32 is composed of two roller motors, which are in contact with the inner surface of the turbine wheel blade root groove, and rely on the friction between the roller motor wheel and the inner surface to drive the array eddy current probe 2 to scan along the axial direction of the turbine wheel blade root groove, ensuring that it can drive the probe to scan along the axial direction of the turbine wheel blade root groove.

[0056] 4. Configure array eddy current detector The array eddy current detector 4 has 64 array channels and is integrated with a multiplexing module, with C scanning function and CT scanning function, and the signal amplitude resolution is 16 bits. It is used to stimulate the array eddy current probe to generate eddy current on the turbine wheel blade root groove detection surface, and record the influence of the eddy current field intensity change caused by the detection surface defect on the impedance change of the array eddy current probe, and extract and record the defect length, depth, position, orientation, etc.

[0057] 5. Debug array eddy current detection system The array eddy current probe 2 is placed at the non-grooved position of the comparison test block 1, and the array eddy current detector 4 is used to excite the array eddy current probe 2 to transmit and receive the induced electromagnetic field, and the array eddy current detector 4 is used to balance the array eddy current coil 22.

[0058] Use the stepping device 3 to uniformly scan the blade root groove of the comparison test block 1 along the axial direction of the blade root groove at a set speed, and display the notch 12 and the through groove 12 on the C-scan diagram of the array eddy current detector 4. By changing the excitation frequency, etc., the angle between the notch 12 signal and the lift-off signal is made as vertical as possible, and then the lift-off signal is adjusted to a horizontal position. At the same time, the C-scan imaging effect of the array eddy current detector 4 is observed. Comprehensive adjustments are made so that both the impedance diagram and the C-scan image are clearly displayed. Scan the notch 12 on the comparison test block 1 at least 3 times at the selected scanning speed to ensure that the notch 12 can be detected each time.

[0059] After the debugging is completed, the detection parameters are saved in the array eddy current detector 4 .

[0060] 6. Actual testing Place the array eddy current probe 2 stably into the turbine wheel blade root groove, ensuring that the coil 22 fits tightly against the surface to be tested.

[0061] Scan at a uniform speed and record suspected defects in the C-scan image and impedance image.

[0062] High-pass filtering is used to suppress interference signals caused by edge effects.

[0063] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0064] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A gas turbine turbine blade root slot array eddy current detection system, characterized in that: It includes a comparison test block, an array eddy current probe, a stepping device and an array eddy current detector; The comparison test block includes a test block base and a groove arranged on the inner surface of the blade root groove of the test block base. The cross-sectional shape and size of the blade root groove on the test block base are the same as the cross-sectional shape of the blade root groove of the turbine wheel to be tested. The array eddy current probe includes a probe frame and an array eddy current coil. The probe frame matches the shape of the blade root slot and is used to be inserted into the blade root slot with a set gap reserved. The array eddy current coil is arranged on the outer surface of the probe frame. The stepping device includes an encoding device and a driving device; the encoding device is integrated on the probe frame, and as the array eddy current probe scans and records the scanned distance, the driving device is used to drive the array eddy current probe to scan along the axial direction of the turbine wheel blade root groove; The array eddy current detector is used to excite the array eddy current probe to generate eddy currents on the turbine blade root groove detection surface, and record the influence of the change of eddy current field intensity caused by the defects of the detection surface on the impedance change of the array eddy current probe, and determine the depth of the defect according to the impedance change. At the same time, the array eddy current detector has C scanning function and CT scanning function.

2. A gas turbine turbine blade root slot array eddy current detection system according to claim 1, characterized in that: The comparison test block has a series of artificial grooves of different sizes and orientations processed at different cross-sectional positions along the blade root groove.

3. The gas turbine turbine blade root slot array eddy current detection system according to claim 2, characterized in that: The orientation of the artificial groove is parallel to the axial direction of the blade root groove, perpendicular to the axial direction of the blade root groove or at 45 degrees to the axial direction of the blade root groove; there is at least one through groove in the artificial groove, and the through groove is perpendicular to the axial direction of the blade root groove.

4. A gas turbine turbine blade root slot array eddy current detection system according to claim 2, characterized in that: The length of the artificial groove is 1mm to 10mm, the depth of the groove is 0.1mm to 5mm, and the width of the groove is not greater than 0.15mm; the spacing of the artificial grooves is 1mm to 10mm.

5. The gas turbine turbine blade root slot array eddy current detection system according to claim 1, characterized in that: An elastic body that fits the shape of the probe frame is attached to the outer periphery of the array eddy current probe frame, and the thickness of the elastic body is greater than the gap between the array eddy current probe frame and the turbine wheel blade root groove.

6. The gas turbine turbine blade root slot array eddy current detection system according to claim 1, characterized in that: The array eddy current coil is arranged along the shape of the array eddy current probe skeleton at the interface between the array eddy current probe skeleton and the elastomer. The length of the array eddy current coil group is not less than half the length of the arc surface of the turbine wheel blade root slot; the array eddy current coil adopts two rows of staggered coils, and each coil can be used as an excitation coil and a receiving coil; the minimum center distance of the array eddy current coil is not greater than 4 times the length of the minimum defect to be detected.

7. The gas turbine turbine blade root slot array eddy current detection system according to claim 1, characterized in that: The encoding device is fixed on the array eddy current probe frame. The encoding device is contacted and positioned with the turbine wheel blade root groove by roller or wire encoding, and is connected to the encoder interface on the array eddy current detector through a cable.

8. The gas turbine turbine blade root slot array eddy current detection system according to claim 1, characterized in that: The drive device drives the probe forward through a roller that contacts the root groove of the turbine wheel blade, and the cargo is integrated with a roller encoding device.

9. The gas turbine turbine blade root slot array eddy current detection system according to claim 1, characterized in that: The array eddy current detector has at least 64 array channels and is integrated with a multiplexing module; the amplitude resolution of the eddy current signal of the array eddy current detector is not less than 16 bits.

10. A method for detecting eddy current of a gas turbine blade root slot array, characterized in that: The method is based on a gas turbine turbine blade root slot array eddy current detection system according to any one of claims 1 to 9, comprising: Slide the array eddy current probe into and place it at the non-grooved position of the blade root groove of the comparison test block, use the array eddy current detector to excite the array eddy current probe to transmit and receive the induced electromagnetic field, and use the array eddy current detector to balance the array eddy current probe coil; The stepping device is used to make the array eddy current probe uniformly scan the blade root groove of the comparison test block along the axial direction of the blade root groove at a set scanning speed, and the groove defects and through grooves are displayed on the C-scan diagram of the array eddy current detector. The angle between the groove signal and the lift-off signal is made vertical by changing the excitation frequency, and then the lift-off signal is adjusted to a horizontal position. At the same time, the C-scan imaging effect of the instrument is observed. Comprehensive adjustments are made to make the impedance diagram and the C-scan image clearly displayed; the groove on the comparison test block is scanned at least 3 times at the selected scanning speed to ensure that the groove defects can be detected each time; after completing the debugging, the detection parameters are saved in the array eddy current detector; During the actual inspection of the turbine impeller blade root groove, the array eddy current probe is stably placed in the turbine impeller blade root groove, the coil is closely fitted to the surface to be inspected, and the scanning speed is kept uniform; the suspected defects found are identified and recorded through the C-scan image and impedance image.

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