CN107806961B - Turbine blade internal flaw barycentric coodinates detection method based on ultrasonic phased array technology - Google Patents

Abstract

The invention discloses a method for detecting the barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology. An ultrasonic phased array detection system is used to detect blades that have been reasonably partitioned, and the detection data is imported into a computer image processing system to detect the partitions. The detected blade areas are fused one by one to obtain the two-dimensional centroid coordinates of the defect; through the design basis of the blade, the three-coordinate machine is used to measure the multiple sets of data of the blade body and the reference edge, and fit the direction along the width of the blade body and the reference line direction. The functional relationship formula is used to derive the three-dimensional barycentric coordinates of the defect according to the spatial relationship, and finally complete the precise positioning and detection of the three-dimensional barycentric coordinates of the defect. It can provide technicians with a three-dimensional positioning method for blade defects, which is more accurate and efficient.

Description

Detection method of barycentric coordinates of internal defects in turbine blades based on ultrasonic phased array technology

technical field

The invention belongs to the technical field of industrial ultrasonic nondestructive testing, in particular to a method for precise detection of three-dimensional barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology.

Background technique

Turbine blades are important components in turbomachinery, such as steam turbines, gas turbines, and water turbines, that guide the fluid to flow in a certain direction and drive the rotor to rotate. Taking a gas turbine as an example, the blade is the core pneumatic part that interacts with the working medium of high temperature, high pressure and high flow rate and realizes energy conversion on the gas turbine. work load. Defects such as shrinkage cavities, porosity, cracks, slag inclusions, etc. may be formed inside the blades, no matter in the manufacturing or service stage, which will seriously affect the working performance, service life and operation safety and reliability of the gas turbine. Therefore, studying the detection technology of turbine blade defects has great and far-reaching strategic significance for improving the manufacturing level of gas turbines in my country and breaking through the technological blockade of developed countries.

Conventional non-destructive testing techniques mainly include radiographic testing, ultrasonic testing, penetrant testing, eddy current testing and other methods. Since the profile of the turbine blade is a complex curved structure, it is usually formed by precision casting of nickel-based superalloy materials with relatively high density. And the thickness of the blade body varies from several millimeters to several tens of millimeters. Conventional penetration testing, eddy current testing and other methods are mainly used to detect defects on the near surface of the object to be tested. The general detection range is several millimeters, which cannot effectively obtain the testing object. The ray detection method mainly uses industrial rays to transilluminate the blade, and uses film imaging to detect the internal defects of the blade. This method has the advantages of high imaging resolution, high sensitivity, intuitive and reliable, etc., and plays an important role in the field of industrial non-destructive testing. However, this method essentially projects the blade on the film along the transillumination direction, so it can only clearly display the two-dimensional feature information of the defect, but cannot display the three-dimensional feature information of the defect in the transillumination direction, even if experienced It is also difficult for professional and technical personnel to accurately estimate the information in this dimension, and the work efficiency is low and the repeatability is poor. Industrial CT technology can directly and accurately reflect the internal structure of the part by taking a large number of slices of the object to be measured, and then using image reconstruction technology to reconstruct the internal structure of the part, so as to obtain accurate three-dimensional feature parameters. However, due to the high cost of industrial CT equipment , The inspection cost is expensive, the parts need to be sliced a lot, the time utilization rate is low, and it is not suitable for large-scale inspection of turbine blades.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for detecting the barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology, aiming at the shortcomings of the above-mentioned prior art, aiming at the detection cost, detection efficiency and improvement in practical engineering applications. According to the requirements of accuracy and other aspects, according to the current blade internal defect positioning method, there are many problems such as low precision, insufficient reliability, and imperfect positioning model.

The present invention adopts following technical scheme:

Based on ultrasonic phased array technology, the method of detecting the barycentric coordinates of internal defects of turbine blades adopts ultrasonic phased array detection system to detect reasonably partitioned blades, and imports the detection data into computer image processing system to obtain the two-dimensional barycentric coordinates of defects; For the design basis of the blade, the three-coordinate machine is used to measure the multiple sets of data of the blade body and the reference edge, and the functional relationship between the width direction of the blade body and the direction of the reference line is fitted, and the three-dimensional barycentric coordinates of the defect are deduced according to the spatial relationship. Complete the three-dimensional barycentric coordinate precision positioning detection of defects.

Further, the following steps are included:

S1. Partition the blade according to the blade body surface and thickness distribution;

S2. Use the ultrasonic phased array probe to scan and test the blade body by area, display A, C, and S on the ultrasonic phased array instrument, and save the data of the test results;

S3. Fusing the detection results of each partition of the blade on the computer in turn, reconstructing the overall image of the blade, and processing the fused image through image processing technology to obtain the two-dimensional centroid coordinates of the defect

S4. Use the three-coordinate machine to detect multiple sets of data of the intersection line between the blade body and the blade design reference, and fit the spatial relationship of the blade body surface;

S5, establish a three-dimensional coordinate system through the design basis of the blade, obtain the depth coordinate z of the defect by establishing the spatial geometric relationship, and derive the three-dimensional barycentric coordinate (x, y, z) of the defect according to the spatial relationship.

Further, in step S1, according to the average thickness of the blade and according to the scanning direction of the probe, the blade root and the leaf crown of the blade are divided into upper and lower regions, and the average thickness of the two regions on the root side is greater than the average thickness of the two regions on the crown side. Thickness, the leaf crown side area is divided according to the sudden change of blade profile curvature.

Further, in step S2, the probe is a linear array point probe of 8 × 8 mm, the scanning is perpendicular to the contact surface, and scanning is performed line by line in each partition along the direction of the airfoil. After scanning one partition, the next partition is scanned. Scan until all areas of the blade body are scanned.

Further, in step S3, according to the probe detection scheme in step S2, the detection image of the blade is obtained, and C display is used as the main display mode. Assuming that the number of pixels of the detection image is M×N, then the coordinates of the centroid of the defect are The calculation is as follows:

Among them, I(x _i , y _i ) represents the pixel value of each pixel of the image read by the computer, I represents the matrix of image pixels, _i represents the row of the matrix I composed of image pixels, and _j represents the matrix I composed of image pixels. List.

Further, in step S4, 30-50 sets of blade profile data are collected by a three-coordinate machine, and a spatial relational formula z=f(y ₁ ) of the blade body surface is fitted, where y ₁ represents the design baseline of the blade.

Further, in step S5, firstly, the center of gravity of the defect is represented by the defect G point, the contact point C represents the contact position between the probe center and the blade surface, and the C' point represents the geometric relationship diagram of the projection point of the contact point C on the xoy plane.

Further, step S5 includes the following steps:

S5.1. Set CC'=z ₀ , AC'=n, OC'=m, OA=a, OC=c, AC=b, C' is the projection of the contact point C on the plane xoy, according to CC'⊥ The plane xoy, then CC'⊥OC', CC'⊥AC', determine the side length relationship as follows:

S5.2. According to the two-dimensional coordinates (x _G , y _G ) of the defect G point obtained in step S3, and CA⊥OA, there is a ² +b ² =c ² ;

S5.3. The distance CC' between the probe center and the contact point C of the blade surface from the plane xoy is equal to the z-axis coordinate z=f(y ₁ ) at the design reference line y ₁ , that is, z ₀ =f(y ₁ ), z ₀ Represents the distance from the contact point C of the probe center to the projection point C' of point C on the plane xoy, combined with the ultrasonic phased array imaging image, to determine the center of gravity position d of the defect;

S5.4. According to z ₀ obtained in step S5.3, and combining steps S5.1 and S5.2, the z-direction coordinate z _G of the center of gravity of the defect is obtained.

Further, in step S5.3, the position d of the center of gravity of the defect is as follows:

Among them: v represents the ultrasonic sound speed in the material, and t represents the ultrasonic propagation time at the defect.

Further, in step S5.4, the z-direction coordinate z _G of the center of gravity of the defect is expressed as follows:

Among them: v represents the ultrasonic sound speed in the material, t represents the ultrasonic propagation time at the defect, CC' represents the distance between the center of the probe and the contact point C of the blade surface and the plane xoy, y ₁ represents the reference line, and GC represents the distance from the defect point to the probe.

Compared with the prior art, the present invention at least has the following beneficial effects:

The invention is based on the ultrasonic phased array technology for the detection method of the barycentric coordinates of the internal defect of the turbine blade, establishes a reference coordinate system based on the design datum of the blade, and uses a three-coordinate machine to measure multiple sets of data of the intersecting line of the blade body and the design datum to fit the blade body The surface relationship between the surface and the benchmark is used to measure the internal defects of the blade through the ultrasonic phased array probe. The detected images are regionally fused with special fusion software, and then the accurate position of the three-dimensional barycentric coordinates of the defect is obtained through the spatial geometric relationship. It provides a positioning method based on the design basis of the blade itself for the precise positioning of blade parts, which can be used as a reference for enterprise defect positioning standards. For the two-dimensional positioning method of blade internal defects currently used in the industry, it can provide technical personnel with blade defects. The three-dimensional positioning method is more accurate and efficient.

Further, the method firstly divides the blade reasonably according to the curved surface and thickness distribution of the blade body; then uses the ultrasonic phased array probe to carry out the division detection of the blade body, and saves the data of the detection results; and then uses a special fusion on the computer. The software TomoView fuses the detection results of each partition of the blade in turn to reconstruct the overall image of the blade; the fused image is processed by image processing technology to obtain the two-dimensional centroid coordinates of the defect; and the three-coordinate machine is used to detect the blade body and the blade. The multiple sets of data of the intersecting lines of the design datum are used to fit the spatial relationship of the blade body surface; finally, a three-dimensional coordinate system is established through the design datum of the blade, and the three-dimensional barycentric coordinates (x, y, z) of the defect are derived according to the spatial relationship. Compared with the manual evaluation of the three-dimensional coordinate positioning of the internal defects of the blade, the accuracy of this method can be improved by 1 to 2 orders of magnitude, and the three-dimensional center of gravity of the defects can be located effectively and accurately.

Further, the partition of the blade is, on the one hand, to facilitate the setting of the thickness parameters during detection with the ultrasonic phased array probe according to the thickness relationship of the blade itself, and to improve the detection efficiency; In order to obtain a more accurate distance CC' between the center of the probe contact surface and its projection point on the xoy surface, the blade surfaces in region 3 and region 4 have abrupt changes, so such partitioning is performed.

Further, according to the probe detection scheme, the blade detection image is obtained, and the C display is the main display method. Assuming that the number of pixel points of the detection image is M×N, the two-dimensional centroid coordinates of the defect are obtained through computer programming technology, according to the interior of the blade. Schematic diagram of defect three-dimensional space detection, and probe detection path relationship, it can be known that the obtained two-dimensional centroid coordinates are the actual x and y coordinates of the internal defect center of gravity. The barycentric z coordinate.

Further, the three-coordinate machine is used to fit the spatial relational expression of the blade body surface, the purpose is to obtain the relational expression z=f(y ₁ ) between the blade surface and the design basis, so that when the probe scans the blade surface, the probe is used to The coordinate value of the center corresponds to z=f(y ₁ ), thereby obtaining the value of CC'. The detection accuracy of the three-coordinate machine is high, which ensures the accurate detection value.

Further, a schematic diagram of the geometric relationship between the contact point and the projection point of the contact point on the xoy plane is established. The purpose is to intuitively express the defect and the basis. The spatial position relationship of the three-coordinate system established by the blade design datum is convenient to push to the accurate relationship of the z-coordinate of the center of gravity of the defect.

Further, according to the above steps, the three-dimensional barycentric coordinates of the center of gravity of the defect are obtained. Since the positioning of the internal defects of the blade parts in the industrial field generally uses the two-dimensional center of gravity or the three-dimensional center of gravity of the defect as the positioning standard, the internal defect of the blade is realized. Positioning, in addition, using the above technical solutions, the detection value of the three-dimensional barycentric coordinates of internal defects with an accuracy of several μ to dozens of μ can be obtained. It is far superior to the currently used three-dimensional barycentric coordinate positioning and evaluation mechanism for defects.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the connection schematic diagram of ultrasonic phased array detection system of the present invention;

Fig. 2 is the implementation flow schematic diagram of the present invention;

Figure 3 is a schematic diagram of the partition detection of the blade;

Fig. 4 is the schematic diagram of the detection result of leaf partition;

FIG. 5 is a schematic diagram of the spatial geometric relationship of ultrasonic phased array detection.

Detailed ways

The present invention provides a method for detecting barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology, and the detection system is shown in FIG. 1 . The blades that have been reasonably partitioned are detected. Through the movement of the probe, the internal defects of the blades are detected and displayed on the ultrasonic phased array instrument, such as A, C, S, etc., and then the data is saved, and the data is imported into the computer image processing system. The fusion software fuses the leaf regions detected by the partitions one by one, and then uses the computer to process the fused leaf images to obtain the two-dimensional centroid coordinates of the defect. Through the design basis of the blade, use a three-coordinate machine to measure multiple sets of data of the blade body and the reference edge, so as to fit the functional relationship between the width direction of the blade body and the direction of the reference line, and obtain the defects by establishing the spatial geometric relationship. The depth coordinate z, and finally complete the three-dimensional barycentric coordinate (x, y, z) precision positioning detection of the defect.

Taking the gas turbine G50 four-stage moving blade as an example, this method establishes a reference coordinate system based on the design datum of the blade, and uses the three-coordinate machine to measure multiple sets of data of the intersection of the blade body and the design datum to fit the curved surface between the blade body surface and the datum. Then use the ultrasonic phased array probe to measure the internal defects of the blade, use special fusion software to perform regional fusion of the detected images, and then obtain the accurate position of the three-dimensional barycentric coordinates of the defect through the spatial geometric relationship.

Please refer to FIG. 2 , a method for detecting barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology of the present invention includes the following steps:

S1. According to the blade body surface and thickness distribution, reasonably partition the blade;

Determine the leaf zoning scheme

The surface of the blade body of the gas turbine blade is a complex spatial curve. For the G50 four-stage moving blade, the overall size specification is 2 to 13 mm, and the thickness of the blade body varies from 2 to 13 mm. In order to facilitate the ultrasonic phased array probe to better fit the blade surface , a line array point probe with a specification of 5L16-CA00 is selected; at the same time, in order to facilitate the detection of the probe, the detection path of the probe needs to be reasonably planned, which requires a reasonable partition of the blade. The partition scheme of the blade is shown in the figure 3 shown.

The average thickness of the 1 and 3 regions of the blade is larger than that of the 2 and 4 regions. The division of the 4 region is mainly based on the blade profile. At the intersection of the 3 and 4 regions, the curvature of the blade profile changes abruptly. In order to facilitate the subsequent steps to establish a three-dimensional Coordinate system, here the 4 areas are divided from there;

S2. Use the ultrasonic phased array probe to perform partition detection on the blade body, and save the data of the detection results;

When using the ultrasonic phased array detector to detect the blade, it is necessary to set parameters such as blade material, ultrasonic sound speed, detection thickness, display mode (A/C/S/B), etc. For the convenience of parameter setting, reduce the operation process, design The scanning of the point probe is perpendicular to the contact surface, and the scanning is performed line by line in each section along the direction of the airfoil. After scanning one section, the scanning of the next section is carried out until the scanning of all areas of the airfoil is completed.

S3. Use the special fusion software TomoView on the computer to fuse the detection results of each partition of the blade in turn to reconstruct the overall image of the blade; process the fused image through image processing technology to obtain the two-dimensional centroid coordinates of the defect;

According to the probe detection scheme in step S2, the detection image of the blade is obtained, and the C display is the main display method. As shown in Figure 4, it is a fused image of a certain area of the blade, which contains two defects.

In order to obtain the coordinates of the centroid of the two defects, assuming that the number of pixels in the image is M×N, the formula for the coordinates of the centroid of the defect is:

Among them, I(x _i , y _i ) represents the pixel value of each pixel of the image read by the computer, I represents the image pixel matrix, _j represents the column of the matrix I composed of image pixels, and _i represents the matrix I composed of image pixels According to the above relationship, the pixel value I(x _i , y _i ) of each pixel point of the image can be read by the computer, and the data can be saved, and then the two-dimensional centroid coordinates of the defect can be obtained by programming

S4. Use the three-coordinate machine to detect multiple sets of data of the intersection line between the blade body and the blade design reference, and fit the spatial relationship of the blade body surface;

30-50 sets of blade profile data were collected by a three-coordinate machine, and Matlab software was used to fit the blade body surface space relationship z=f(y ₁ ), and the y ₁ axis represented the design baseline of the blade.

S5, establish a three-dimensional coordinate system through the design basis of the blade, and derive the three-dimensional barycentric coordinates (x, y, z) of the defect according to the spatial relationship.

The gas turbine blade profile is a complex space curved surface. In order to better illustrate the ultrasonic phased array probe detection model, a geometric relationship diagram as shown in Figure 5 is established.

Among them, the defect G point represents the center of gravity of the defect, the contact point C represents the contact position between the probe center and the blade surface, and the C' point represents the projection point of the contact point C on the xoy plane. Let CC'=z ₀ , AC'=n, OC'=m, OA=a, OC=c, AC=b.

S5.1. Because C' is the projection of the contact point C on the plane xoy, there is a relational formula CC'⊥ plane xoy, then CC'⊥OC', CC'⊥AC', according to the side length relationship:

S5.2. In step S3, the pixel relationship of the image has been used to read the information of each pixel of the defect image with a computer, and the two-dimensional centroid coordinates (x, y) of the defect are obtained through computer programming. The two-dimensional geometric information of Fig. 5 and the three-dimensional geometric diagram of Fig. 5, it can be known that the two-dimensional coordinates (x _G , y _G ) of the defect G point can be obtained by formula 1; and because the probe is perpendicular to the blade surface to scan line by line , then CA⊥OA is satisfied, then:

a ² +b ² =c ² (3)

S5.3. To obtain the coordinates of the defect in the z-axis direction in this coordinate system, the distance from C to C' must be known. It is known that the spatial relationship between the blade design datum and the blade surface profile z=f(y ₁ ) is realized by the three-coordinate machine in step S4. Since the probe has a gentle curvature along the blade scanning direction, and the probe is 8×8mm Line array point probe, it can be considered that when the probe moves line by line in a certain partition, the distance CC' between the probe center and the contact point C of the blade surface from the plane xoy is equal to the z-axis coordinate z ₌ f ( y ₁ ), that is, z ₀ =f(y ₁ ), z ₀ represents the distance from the center contact point C of the probe to the projection point C' of point C on the plane xoy, and combined with the ultrasonic phased array imaging image, the defect can be obtained The position d of the center of gravity, according to the relation:

Among them: v represents the ultrasonic sound speed in the material, and t represents the ultrasonic propagation time at the defect.

which is The gas turbine blade is made of nickel-based superalloy. The sound speed of ultrasonic waves in this material is 5770m/s. The ultrasonic propagation time at the defect can be read through the A/S display diagram of the phased array measuring instrument. The general time t is 10 ^-8 to 10 ^-9 orders of magnitude, that is, the fractional part of the measured CG value is between several μ and tens of μ.

S5.4, z ₀ =f(y ₁ ) obtained from step S5.3, combined with relational expressions 2 and 3, the z-direction coordinate z _G of the defective center of gravity:

Combined with the two-dimensional centroid coordinates of the defect in step S3 The actual three-dimensional barycentric coordinates of the available defects are The laboratory model of the CMM is Global classic SR575, and its measurement accuracy-maximum allowable detection error MPEP≤1.9μm, that is, the fractional part of z ₀ =f(y ₁ ) is in the range of several μ, and the accuracy of z _G is comprehensively considered can reach tens of μ;

On the other hand, gas turbine blades are generally formed by precision casting, and the surface accuracy can generally reach 2 wires (10 μ).

Taking into account the measurement accuracy of the defect coordinates of the present invention, it can reach the same order of magnitude as the precision requirements of blade precision casting, and the accuracy of the artificial film evaluation of the blade ray detection commonly used in the industry is only mm. It can improve the positioning accuracy of the three-dimensional barycentric coordinates of defects by 1 to 2 orders of magnitude, which is far superior to the currently used evaluation mechanism for the three-dimensional barycentric coordinates of defects.

The invention takes the gas turbine G50 four-stage moving blade as an example, establishes a three-dimensional coordinate system suitable for the blade based on the design basis of the blade, establishes a schematic diagram of the three-dimensional geometric relationship of the internal defect of the blade through the ultrasonic phased array detection technology, and uses a three-coordinate machine to measure the surface type of the blade. Multiple sets of data on the surface of the blade, fit the relationship of the blade profile curve z=f(y ₁ ), and combine the ultrasonic phased array C display to calculate the two-dimensional centroid coordinates of the defect through computer image processing technology, and then derive the geometric relationship of the blade internal defect. Three-dimensional coordinates of the center of gravity of the defect Realize precise location measurement of defects.

At present, the accuracy of medical B-ultrasound detection of physiological lesions in the human body can generally only reach the mm level, and because the specific positions of the internal physiological organs of the human body are different, generally only a rough detection of the size of the lesion can be achieved, and the location of the lesion cannot be located. Preferably, the method of the present invention also provides a new idea of precise localization of lesions for B-ultrasound detection of physiological lesions in the human body in the medical field. The present invention can not only achieve higher detection accuracy, but also provide reference for the location of lesions.

The above content is only to illustrate the technical idea of the present invention, and cannot 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 all fall within the scope of the claims of the present invention. within the scope of protection.

Claims (7)

1. A method for detecting the barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology, which is characterized in that the ultrasonic phased array detection system is used to detect the blades that have been reasonably partitioned, and the detection data is imported into a computer image processing system to obtain the defect's Two-dimensional center of mass coordinates; through the design basis of the blade, use a three-coordinate machine to measure multiple sets of data of the blade body and the reference edge, fit the functional relationship between the width direction of the blade body and the direction of the reference line, and deduce the defects according to the spatial relationship The three-dimensional barycentric coordinates of the defect are finally completed, and the precise positioning and detection of the three-dimensional barycentric coordinates of the defect includes the following steps: S1. Partition the blade according to the blade body surface and thickness distribution; S2. Use the ultrasonic phased array probe to scan and test the blade body by area, display A, C, and S on the ultrasonic phased array instrument, and save the data of the test results; S3. Fusing the detection results of each partition of the blade on the computer in turn, reconstructing the overall image of the blade, and processing the fused image through image processing technology to obtain the two-dimensional centroid coordinates of the defect S4. Use the three-coordinate machine to detect multiple sets of data of the intersection line between the blade body and the blade design reference, and fit the spatial relationship of the blade body surface; S5. Establish a three-dimensional coordinate system based on the design basis of the blade, obtain the depth coordinate z of the defect by establishing the spatial geometric relationship, and derive the three-dimensional barycentric coordinate (x, y, z) of the defect according to the spatial relationship, which specifically includes the following steps: S5.1. Set CC'=z ₀ , AC'=n, OC'=m, OA=a, OC=c, AC=b, C' is the projection of the contact point C on the plane xoy, according to CC'⊥ The plane xoy, then CC'⊥OC', CC'⊥AC', determine the side length relationship as follows: S5.2. According to the two-dimensional coordinates (x _G , y _G ) of the defect G point obtained in step S3, and CA⊥OA, there is a ² +b ² =c ² ; S5.3. The distance CC' between the probe center and the contact point C of the blade surface from the plane xoy is equal to the z-axis coordinate z=f(y ₁ ) at the design reference line y ₁ , that is, z ₀ =f(y ₁ ), z ₀ Represents the distance from the contact point C of the probe center to the projection point C' of point C on the plane xoy, combined with the ultrasonic phased array imaging image, to determine the center of gravity position d of the defect; S5.4. According to z ₀ obtained in step S5.3, and combining steps S5.1 and S5.2, the z-direction coordinate z _G of the center of gravity of the defect is obtained. 2. The method for detecting the barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology according to claim 1, wherein in step S1, according to the average thickness of the blades, according to the scanning direction of the probe, the blades of the blades are detected. The root and leaf crown are divided into upper and lower regions. The average thickness of the two regions at the root side is greater than the average thickness of the two regions at the crown side. The leaf crown side region is divided according to the sudden change of blade profile curvature. 3. The method for detecting barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology according to claim 1, wherein in step S2, the probe is a linear array point probe of 8 × 8 mm, and the scanning is perpendicular to the contact Scanning is performed line by line in each partition along the airfoil direction. After scanning one partition, the next partition is scanned until the scanning of all areas of the airfoil is completed. 4. The method for detecting barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology according to claim 1, characterized in that, in step S3, according to the probe detection scheme in step S2, a detection image of the blade is obtained, and a detection image of the blade is obtained by C. Display is the main display mode. Assuming that the number of pixels in the detected image is M×N, the coordinates of the centroid of the defect The calculation is as follows: Among them, I(x _i , y _j ) represents the pixel value of each pixel of the image read by the computer, I represents the image pixel matrix, i represents the row of the matrix I formed by the image pixels, and j represents the image pixel formed by the matrix I. List. 5 . The method for detecting barycentric coordinates of internal defects of turbine blades based on ultrasonic phased array technology according to claim 1 , wherein in step S4 , 30 to 50 sets of blade profile data are collected by a three-coordinate machine, and fitted The airfoil surface space relational formula z=f(y ₁ ), y ₁ represents the design reference line of the blade. 6. The method for detecting the center of gravity coordinates of defects in turbine blades based on ultrasonic phased array technology according to claim 1, characterized in that, in step S5.3, the center of gravity position d of the defect is as follows: Among them: v represents the ultrasonic sound speed in the material, and t represents the ultrasonic propagation time at the defect. 7. The method for detecting the center of gravity of a defect in a turbine blade based on ultrasonic phased array technology according to claim 1, wherein in step S5.4, the z-direction coordinate z _G of the center of gravity of the defect is represented as follows: Among them: v represents the ultrasonic sound speed in the material, t represents the ultrasonic propagation time at the defect, CC' represents the distance between the center of the probe and the contact point C of the blade surface and the plane xoy, y ₁ represents the reference line, and GC represents the distance from the defect point to the probe.