Gas turbine wheel disc blade root groove array eddy current coil arrangement and excitation method and device

Abstract

The invention discloses a gas turbine wheel disc blade root groove array eddy current coil arrangement and excitation method and device, and the method improves the detection sensitivity, resolution and accuracy through optimizing the key parameters of the array eddy current coil, such as the inner diameter, the outer diameter, the number of turns, the height and the frequency. The arrangement and the number of the array eddy current coils are set according to a set mode, so that the fluctuation of detection sensitivity is reduced, the detection rate of different orientation defects is improved, and the risks of missing detection and false detection are reduced; and through optimization of excitation and receiving modes, mutual interference among different coils is further reduced, and the detection sensitivity is improved. By reasonably designing coil arrangement and an excitation mode, an efficient and accurate detection technical scheme is provided for gas turbine wheel disc blade root groove defect detection.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing of gas turbine components, and specifically relates to an eddy current coil arrangement and excitation method and device for a gas turbine wheel blade root slot array. Background Art

[0002] A gas turbine is a continuous-flow rotating machine (single machine) that converts thermal energy into mechanical work, including a compressor, equipment for heating the working fluid (such as a combustion chamber), a turbine, a control system, and auxiliary equipment. Its working principle is: the compressor inhales air, pressurizes it, and then sends it into the combustion chamber. The fuel pump sprays the fuel into the combustion chamber through the nozzle to mix with the air and burn. The generated high-temperature and high-pressure combustion gas enters the turbine to expand and do work, and finally the exhaust gas is discharged into the atmosphere and releases heat. Among them, part of the expansion work is transmitted to the compressor and other auxiliary machinery through the transmission shaft, and the rest of the expansion work is output to the outside for power generation or as power.

[0003] The turbine wheel is one of the core components of the gas turbine. The blade root groove processed in the circumferential direction of the turbine wheel is the key part of the assembly of the turbine wheel and the turbine blade. The blade root groove of the turbine wheel needs to withstand complex cyclic stress during service, and it is very easy to produce defects such as cracks. Therefore, the implementation of meticulous and effective non-destructive testing of the blade root groove of the turbine wheel is an important measure to ensure the safe and stable operation of the gas turbine.

[0004] Array eddy current testing technology is very suitable for high-sensitivity and high-precision non-destructive testing of turbine blade root slots due to its advantages of large-area scanning, high sensitivity, and direct coupling with complex-shaped parts. By optimizing the arrangement and excitation method of array eddy current coils, the detection efficiency and accuracy can be further improved, providing strong support for the inspection and maintenance of gas turbines.

[0005] In the array eddy current testing of turbine blade root slots, coil arrangement is one of the key factors. Array eddy current probes are usually composed of multiple independently working coils, which are arranged in a specific way. By adjusting the arrangement and number of coils, efficient detection of linear defects in different directions can be achieved. The excitation method is another key link. By designing an appropriate excitation method, the sensitivity and reliability of array eddy current testing can be further improved.

[0006] In summary, array eddy current testing technology has broad application prospects in the non-destructive testing of gas turbine turbine blade root slots. By rationally designing the coil arrangement and excitation method, efficient and accurate detection of blade root slot defects can be achieved, providing important guarantees for the safe and stable operation of gas turbines. Summary of the invention

[0007] The purpose of the present invention is to provide a method and device for arranging and exciting eddy current coils in a blade root slot array of a gas turbine wheel disc, aiming to achieve efficient and accurate detection of blade root slot defects by reasonably designing the coil arrangement and excitation method.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: The present invention provides a method for arranging and exciting eddy current coils in a gas turbine wheel blade root slot array, comprising: 1) Based on the structural dimensions and electromagnetic characteristics of the blade root slot of the turbine disk being tested, determine the inner diameter, outer diameter, number of turns, height and frequency of the array eddy current coil; 2) Based on the characteristic parameters of the coil, combined with the orientation and size of the defects to be detected, and the requirements for consistency of detection sensitivity, determine the length of the array eddy current coil group, the center distance of the coil, the arrangement and the number of coils; 3) Based on the arrangement of array eddy current coils, a combination of simulation and experiment is used to obtain the sensitivity of defects of different orientations and sizes to the excitation mode, and to determine the excitation and receiving modes of the array eddy current coils in the root slots of the turbine wheel.

[0009] A further improvement of the present invention is that, in step 1), the inner diameter and outer diameter of the coil are determined according to the structural dimensions and surface curvature of the blade root groove of the turbine wheel disc to be inspected, so as to ensure that the coil can fit closely to the inspected part; The outer diameter of the coil is as large as possible while being able to fit the detection part tightly, so as to induce a stronger and deeper eddy current field in the blade root groove of the turbine wheel being detected; The inner diameter of the coil should be as small as possible to make the induced magnetic field distribution more concentrated; The number of coil turns is selected based on the conductivity, thickness and surface roughness of the blade root groove of the turbine wheel disc to be tested; the maximum number of turns is selected under the conditions of meeting the stability of the eddy current detection signal and the structural size limit of the eddy current probe; The coil height should be as small as possible with the same number of turns, so as to induce a more concentrated and stronger eddy current field at the detected part; The coil frequency takes into account the penetration depth and intensity of the eddy current field at the same time. The optimal detection frequency is selected according to the detection depth and detection sensitivity requirements of the detected part. f opt Determined by the following formula:

[0010] in, ρ is the resistivity of the detected part, t To detect depth.

[0011] A further improvement of the present invention is that in step 2), the length of the array eddy current coil group is determined according to the area to be covered by a single scan of the turbine wheel blade root slot, and it is required that at most two axial scans should cover the entire turbine wheel blade root slot detection surface, so the length of the coil group is not less than half of the length of the cross-sectional profile of the turbine wheel blade root slot detection surface; The steps for selecting the center distance of the array eddy current coils include: First, determine the minimum center distance allowed for the array eddy current coils to ensure that the excitation magnetic fields of the excitation coils and the induced magnetic fields of the detection coils do not interfere with each other; Secondly, the center distance is appropriately increased based on the minimum center distance to obtain a center distance with relatively high detection sensitivity; Finally, combined with the curvature of the inspected part of the turbine blade root slot, the coil center distance is comprehensively determined while ensuring the fit between the array eddy current coil group and the inspected part. The array eddy current coils are arranged in two rows in a staggered manner, with two adjacent rows of coils staggered at a set angle. Number of eddy current coil arrays N Determined by the following formula:

[0012] in, L The cross-sectional profile length of the turbine blade root groove inspection surface covered by a single scan. a is the center distance between single row array eddy current coils.

[0013] A further improvement of the present invention is that the inner diameter of the array eddy current coil is 0.3 mm to 0.8 mm, the outer diameter is 1 mm to 2 mm, and the number of turns is 5 to 10 turns.

[0014] A further improvement of the present invention is that the frequency of the array eddy current coil is 500kHz to 1200kHz.

[0015] A further improvement of the present invention is that the center distance of the array eddy current coils is 2.5 mm to 4 mm, and the number of the array eddy current coil groups is generally not more than 120.

[0016] A further improvement of the present invention is that two rows of coils of the array eddy current coil group are arranged at a 30° interval, and the center distance between adjacent coils in one row is equal to the center distance between the coils in one row and two adjacent coils in an adjacent row.

[0017] A further improvement of the present invention is that, in step 3), the excitation and reception of the array eddy current coils are realized by multiplexing technology; Among them, the excitation and receiving method of the array eddy current coil, combined with the electromagnetic characteristics of the turbine wheel blade root slot being tested, adopts a short-distance transmission-reception method; the coils are excited in sequence starting from one end of the array eddy current coil group, and the adjacent coils receive the electromagnetic signal generated by the exciting coil; at the next moment, the previous receiving coil acts as the transmitting coil, and its next adjacent coil receives the electromagnetic signal generated by the exciting coil, and so on.

[0018] A further improvement of the present invention is that the short-distance transmission-reception mode uses two coils in the same row as transmitting coils, and two adjacent coils in the same row and three adjacent coils in the adjacent row as receiving coils.

[0019] The present invention also provides a gas engine turbine wheel blade root slot array eddy current coil arrangement and excitation device, comprising: The first confirmation module determines the inner diameter, outer diameter, number of turns, height and frequency of the array eddy current coil based on the structural dimensions and electromagnetic characteristics of the detected turbine wheel blade root slot; The second confirmation module determines the length of the array eddy current coil group, the coil center distance, the arrangement and the number of coils based on the characteristic parameters of the coils, combined with the orientation and size of the defects to be detected, and the sensitivity consistency requirements of the detection; The third confirmation module, based on the arrangement of array eddy current coils, adopts a combination of simulation and experiment to obtain the sensitivity of defects of different orientations and sizes to the excitation method, and determines the excitation and receiving methods of the eddy current coils in the root slot array of the turbine wheel blade.

[0020] Compared with the prior art, the present invention has at least the following beneficial technical effects: The gas turbine wheel disc blade root slot array eddy current coil arrangement and excitation method and device provided by the present invention improve the sensitivity, resolution and accuracy of detection by optimizing the key parameters such as the inner diameter, outer diameter, number of turns, height, frequency, etc. of the array eddy current coil; by setting the array eddy current coil arrangement and number in a set manner, the fluctuation of detection sensitivity is reduced, the detection rate of defects in different orientations is improved, and the risk of missed detection and false detection is reduced; by optimizing the excitation and receiving methods, the mutual interference between different coils is further reduced, and the detection sensitivity is improved. Finally, high-sensitivity, high-resolution, and high-reliability array eddy current detection of gas turbine wheel disc blade root slots is realized, which greatly reduces the risk of missed detection and false detection of defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The diagram is a schematic diagram of the arrangement and excitation method of the eddy current coils of the gas engine turbine wheel blade root slot array of the present invention.

[0022] Figure 2 The present invention is a schematic diagram of the coil arrangement and excitation method of the eddy current coil of the gas engine turbine wheel blade root slot array.

[0023] Figure 3 The present invention is a schematic diagram of the arrangement and excitation method of eddy current coils in the root slot array of a gas engine turbine wheel.

[0024] Figure 4 The present invention is a structural block diagram of the arrangement of eddy current coils and the excitation device of the turbine wheel blade root slot array of the gas engine.

[0025] Description of reference numerals: 1-coil, 11-inner diameter, 12-outer diameter, 13-number of turns, 14-height, 21-length of array eddy current coil group, 22-coil center distance, 23-array eddy current coil arrangement, T-transmitting coil, R-receiving coil. DETAILED DESCRIPTION

[0026] 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.

[0027] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0028] 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, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0029] 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.

[0030] 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.

[0031] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] Example 1 like Figure 1 to Figure 3 As shown, the present invention provides a method for arranging and exciting eddy current coils of a gas turbine blade root slot array, comprising: S1, based on the structural dimensions and electromagnetic characteristics of the detected turbine wheel blade root slot, determine the inner diameter 11, outer diameter 12, number of turns 13, height 14 and frequency of the array eddy current coil 1; S2, based on the characteristic parameters of coil 1, combined with the orientation and size of the defect to be detected, and the sensitivity consistency requirements of the detection, determine the length 21 of the array eddy current coil group, the coil center distance 22, the arrangement 23 and the number of coils; S3, based on the arrangement of the array eddy current coil 1, a combination of simulation and experiment is used to obtain the sensitivity of defects of different orientations and sizes to the excitation mode, and determine the excitation and receiving mode of the array eddy current coil 1 of the turbine wheel blade root slot.

[0033] In this embodiment, step S1 includes: the inner diameter 11 and the outer diameter 12 of the coil 1 need to be determined according to the structural dimensions and surface curvature of the detected turbine wheel blade root groove to ensure that the coil 1 can fit closely to the detected part and improve the sensitivity and accuracy of the detection.

[0034] The outer diameter 12 of the coil 1 should be appropriately large while being able to fit closely to the detection location, so as to induce a stronger and deeper eddy current field in the blade root groove of the turbine wheel being detected.

[0035] The inner diameter 11 of the coil 1 should be appropriately small to make the induced magnetic field distribution more concentrated and improve the sensitivity and resolution of the detection.

[0036] The number of turns 13 of coil 1 should be selected comprehensively based on the conductivity, thickness, and surface roughness of the detected turbine wheel blade root groove. Under the conditions of meeting the stability of eddy current detection signals and the structural size restrictions of eddy current probes, a larger number of turns 13 should be selected to improve sensitivity and resolution and detect tiny defects more efficiently.

[0037] The height 14 of the coil 1 should be as small as possible with the same number of turns 13, so as to induce a more concentrated and stronger eddy current field at the detected part, thereby improving the sensitivity and resolution of eddy current detection.

[0038] The frequency of coil 1 should take into account both the penetration depth and intensity of the eddy current field and should be selected based on the detection depth and detection sensitivity requirements of the detected part.

[0039] Preferably, the optimal detection frequency f opt It is generally determined by the following formula:

[0040] in, ρ is the resistivity of the detected part, t To detect depth.

[0041] In this embodiment, step S2 includes: the length of the array eddy current coil group 21 should be determined based on the area to be covered by a single scan of the turbine wheel blade root slot. Generally, a maximum of two axial scans are required to cover the entire turbine wheel blade root slot detection surface. Therefore, the length of the coil group should not be less than half of the cross-sectional contour length of the turbine wheel blade root slot detection surface.

[0042] The steps of selecting the center distance 22 of the array eddy current coil 1 include: S21, determine the minimum center distance allowed for the array eddy current coil 1, ensure that the excitation magnetic fields of the excitation coils and the induced magnetic fields of the detection coils do not interfere with each other, and avoid the overlap of electromagnetic fields caused by too small coil center distance 22, which may cause the risk of missed detection and false detection; S22, appropriately increase the coil center distance 22 on the basis of the minimum center distance to obtain a coil center distance 22 with relatively high detection sensitivity.

[0043] S23, combining the curvature of the inspected portion of the turbine wheel blade root slot, and ensuring the fit between the array eddy current coil group and the inspected portion, comprehensively determine the coil center distance 22.

[0044] The array eddy current coil arrangement 23 adopts a two-row staggered arrangement, and the two adjacent rows of coils are staggered by a set angle to reduce the fluctuation of detection sensitivity, improve the detection rate of defects with different orientations, and reduce the possibility of missed detection.

[0045] Number of array eddy current coils 1 N Determined by the following formula:

[0046] in, L The cross-sectional profile length of the turbine blade root groove inspection surface covered by a single scan. a is the center distance between single row array eddy current coils.

[0047] In this embodiment, step S3 includes: the excitation and reception of the array eddy current coils 1 are realized by multiplexing technology to avoid mutual interference between different coils 1.

[0048] Specifically, the above functions are realized by a multiplexer. The multiplexer may be integrated on the array eddy current probe or on the host of the array eddy current detection instrument. The present invention does not make any specific limitation on this.

[0049] The excitation and receiving mode of the array eddy current coil 1 is combined with the electromagnetic characteristics of the detected turbine wheel blade root slot. The short-distance transmission and reception mode is more sensitive to small defects near the surface, so the short-distance transmission-reception mode is adopted. Starting from one end of the array eddy current coil group, the coils are excited in sequence, and the adjacent coils receive the electromagnetic signal generated by the exciting coil; at the next moment, the previous receiving coil acts as the transmitting coil, and the next adjacent coil receives the electromagnetic signal generated by the exciting coil, and so on.

[0050] Specifically, the array eddy current coil 1 can be used as an excitation coil or a receiving coil. However, in this transmitting and receiving mode, only a single array eddy current coil 1 can use one of the modes at the same time.

[0051] Specifically, by sequentially exciting the array eddy current coil 1 from one end to the other, the entire process of exciting and receiving the coils in the entire length direction of the array eddy current coil group is completed in a very short time. At the same time, by matching the axial scanning speed of the array eddy current probe, full coverage of detection in the length direction of the array eddy current coil group is achieved.

[0052] Preferably, the inner diameter 11 of the array eddy current coil 1 is 0.3 mm to 0.8 mm, the outer diameter 12 is 1 mm to 2 mm, and the number of turns 13 is 5 to 10 turns.

[0053] Preferably, the frequency of the array eddy current coil 1 is 500kHz to 1200kHz.

[0054] Preferably, the center distance 22 of the array eddy current coil is 2.5 mm to 4 mm, and the number of array eddy current coil groups is N Generally not more than 120.

[0055] Preferably, the two rows of coils in the array eddy current coil group are arranged at a 30° angle, and the center distance 22 between adjacent coils in the row is equal to the center distance 22 between the coils in the row and two adjacent coils in the adjacent row.

[0056] Preferably, the short-distance transmission-reception mode generally uses two coils in the same row as transmitting coils, and two adjacent coils in the same row and three adjacent coils in adjacent rows as receiving coils.

[0057] Example 2 like Figure 4 As shown, the eddy current coil arrangement and excitation device for the turbine wheel blade root slot array provided by the present invention comprises: The first confirmation module determines the inner diameter, outer diameter, number of turns, height and frequency of the array eddy current coil based on the structural dimensions and electromagnetic characteristics of the detected turbine wheel blade root slot; The second confirmation module determines the length of the array eddy current coil group, the coil center distance, the arrangement and the number of coils based on the characteristic parameters of the coils, combined with the orientation and size of the defects to be detected, and the sensitivity consistency requirements of the detection; The third confirmation module, based on the arrangement of array eddy current coils, adopts a combination of simulation and experiment to obtain the sensitivity of defects of different orientations and sizes to the excitation method, and determines the excitation and receiving methods of the eddy current coils in the root slot array of the turbine wheel blade.

[0058] Example 3 Step S1: Determine the parameters of the array eddy current coil Taking the structural dimensions and surface curvature of the blade root slot of the turbine wheel of a 9FA gas engine to be detected as an example, in order to meet the requirements for detecting blade root slot cracks at the minimum curvature radius, the inner diameter 11 of the array eddy current coil 1 is 0.4 mm, the outer diameter 12 is 1 mm, the number of turns 13 is 6 turns, the height 14 is 0.5 mm, and the frequency is 1000 kHz.

[0059] Step S2: Determine the arrangement of the array eddy current coil group According to the cross-sectional profile length of the 9FA gas turbine turbine blade root slot detection surface, the two rows of coils in the array eddy current coil group are staggered by 30°. The length 21 of the array eddy current coil group is selected to be 100 mm, the center distance 22 is 3 mm, and the number of coils is 70.

[0060] Step S3: Determine the transmission-reception mode Two coils in the same row are used as transmitting coils, and two adjacent coils in the same row and three adjacent coils in adjacent rows are used as receiving coils.

[0061] At the same time, tests were carried out on the blade root groove of the turbine impeller of a 9FA gas turbine to evaluate the sensitivity, accuracy and reliability of the detection system.

[0062] 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.

[0063] 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. Arrangement and excitation method of eddy current coils for blade root slot array of gas turbine wheel disc, characterized in that: include: 1) Based on the structural dimensions and electromagnetic characteristics of the blade root slot of the turbine disk being tested, determine the inner diameter, outer diameter, number of turns, height and frequency of the array eddy current coil; 2) Based on the characteristic parameters of the coil, combined with the orientation and size of the defects to be detected, and the requirements for consistency of detection sensitivity, determine the length of the array eddy current coil group, the center distance of the coil, the arrangement and the number of coils; 3) Based on the arrangement of array eddy current coils, a combination of simulation and experiment is used to obtain the sensitivity of defects of different orientations and sizes to the excitation mode, and to determine the excitation and receiving modes of the array eddy current coils in the root slots of the turbine wheel.

2. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 1, characterized in that: In step 1), the inner diameter and outer diameter of the coil are determined according to the structural dimensions and surface curvature of the blade root groove of the turbine wheel disc to be inspected, so as to ensure that the coil can fit closely to the inspected part; The outer diameter of the coil is as large as possible while being able to fit the detection part tightly, so as to induce a stronger and deeper eddy current field in the blade root groove of the turbine wheel being detected; The inner diameter of the coil should be as small as possible to make the induced magnetic field distribution more concentrated; The number of coil turns is selected based on the conductivity, thickness and surface roughness of the blade root groove of the turbine wheel disc to be tested; the maximum number of turns is selected under the conditions of meeting the stability of the eddy current detection signal and the structural size limit of the eddy current probe; The coil height should be as small as possible with the same number of turns, so as to induce a more concentrated and stronger eddy current field at the detected part; The coil frequency takes into account the penetration depth and intensity of the eddy current field at the same time. The optimal detection frequency is selected according to the detection depth and detection sensitivity requirements of the detected part. f opt Determined by the following formula: in, ρ is the resistivity of the detected part, t To detect depth.

3. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 1, characterized in that: In step 2), the length of the array eddy current coil group is determined according to the area to be covered by a single scan of the turbine wheel blade root slot. It is required that at most two axial scans should cover the entire turbine wheel blade root slot detection surface. Therefore, the length of the coil group is not less than half of the length of the cross-sectional profile of the turbine wheel blade root slot detection surface. The steps for selecting the center distance of the array eddy current coils include: First, determine the minimum center distance allowed for the array eddy current coils to ensure that the excitation magnetic fields of the excitation coils and the induced magnetic fields of the detection coils do not interfere with each other; Secondly, the center distance is appropriately increased based on the minimum center distance to obtain a center distance with relatively high detection sensitivity; Finally, combined with the curvature of the inspected part of the turbine blade root slot, the coil center distance is comprehensively determined while ensuring the fit between the array eddy current coil group and the inspected part. The array eddy current coils are arranged in two rows in a staggered manner, with two adjacent rows of coils staggered at a set angle. Number of eddy current coil arrays N Determined by the following formula: in, L The cross-sectional profile length of the turbine blade root groove inspection surface covered by a single scan. a is the center distance between single row array eddy current coils.

4. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 3, characterized in that: The inner diameter of the array eddy current coil is 0.3mm-0.8mm, the outer diameter is 1mm-2mm, and the number of turns is 5-10 turns.

5. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 3, characterized in that: The frequency of the array eddy current coil is 500kHz~1200kHz.

6. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 3, characterized in that: The center distance of the array eddy current coil is 2.5mm to 4mm, and the number of array eddy current coil groups is generally not more than 120.

7. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 3, characterized in that: The two rows of coils in the array eddy current coil group are staggered by 30 degrees, and the center distance between adjacent coils in the same row is equal to the center distance between the coil in the same row and the two adjacent coils in the adjacent row.

8. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 1, characterized in that: In step 3), the excitation and reception of the array eddy current coils are realized by multiplexing technology; Among them, the excitation and receiving method of the array eddy current coil, combined with the electromagnetic characteristics of the turbine wheel blade root slot being tested, adopts a short-distance transmission-reception method; the coils are excited in sequence starting from one end of the array eddy current coil group, and the adjacent coils receive the electromagnetic signal generated by the exciting coil; at the next moment, the previous receiving coil acts as the transmitting coil, and its next adjacent coil receives the electromagnetic signal generated by the exciting coil, and so on.

9. The gas engine turbine blade root slot array eddy current coil arrangement and excitation method according to claim 8, characterized in that: The short-distance transmission-reception method uses two coils in the same row as transmitting coils, and two adjacent coils in the same row and three adjacent coils in the adjacent row as receiving coils.

10. A gas turbine wheel blade root slot array eddy current coil arrangement and excitation device, characterized in that: include: The first confirmation module determines the inner diameter, outer diameter, number of turns, height and frequency of the array eddy current coil based on the structural dimensions and electromagnetic characteristics of the detected turbine wheel blade root slot; The second confirmation module determines the length of the array eddy current coil group, the coil center distance, the arrangement and the number of coils based on the characteristic parameters of the coils, combined with the orientation and size of the defects to be detected, and the sensitivity consistency requirements of the detection; The third confirmation module, based on the arrangement of array eddy current coils, adopts a combination of simulation and experiment to obtain the sensitivity of defects of different orientations and sizes to the excitation method, and determines the excitation and receiving methods of the eddy current coils in the root slot array of the turbine wheel blade.

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