A method for calculating the area of a guider throat based on point cloud data

Abstract

The application discloses a kind of based on the method for measuring and calculating throat area of director based on point cloud data, belong to the field of geometric parameter precision measurement.The application includes the parsing and topological relationship reconstruction of the scanning measurement data file of director, the automatic segmentation of the point cloud data of turbine director, the calculation of the throat area of double guide vane and the output of the throat area of turbine director.The throat area obtained by the intersection method of constructing space plane and double guide vane is not related to empirical formula, and the measurement accuracy is higher.The application "diffraction" the automatic segmentation of all adjacent double guide vane data from the point cloud data automatic segmentation of turbine director by the automatic segmentation result of blade cylindrical surface section data, avoids artificial operation of segmentation point cloud, and obtains the throat area of turbine director based on the calculation of blade throat area using double guide vane data set.The application also has the advantages of strong repeatability, high measurement efficiency, short measurement period, avoiding blade surface scratch and the like.

Description

Technical Field

[0001] This invention relates to a method for accurately evaluating the throat area of ​​an aero-engine turbine guide vane, belonging to the field of precision measurement of geometric parameters. Background Technology

[0002] The size of the throat area of ​​the turbine guide vane plays a crucial role in the smooth operation and overall performance of a turbine engine, directly affecting the engine's thrust, speed, temperature, airflow field, etc., and is an important parameter in the design and assembly of aero engines.

[0003] Currently, the "equivalent method" is commonly used in engineering surveying to calculate the throat area of ​​blades. This involves measuring the minimum blade width and the distance between the upper and lower edge plates at fixed points on the blade using a coordinate measuring machine or other mechanical measuring devices as height values, and then calculating the throat area of ​​the double guide vane using relevant formulas. However, because the blade profile is a complex, twisted curved surface, the coordinate points acquired by the measuring device are not necessarily accurate and reliable. Furthermore, the actual throat cross-section is not a regular quadrilateral. Therefore, there will always be a certain difference between the blade throat area calculated using the "equivalent method" and the actual throat area. In addition, using contact measuring devices is prone to causing scratches on the blade surface, has poor repeatability, and has a long measurement cycle. Summary of the Invention

[0004] To address the problems of inaccurate measurement results when using the "equivalent method" to calculate the throat area in existing aero-engine throat area measurement and evaluation processes, and the risks of blade surface scratches, poor repeatability, low measurement efficiency, and long measurement cycles caused by complex contact-type measurement devices, this invention aims to provide a guide vane throat area calculation method based on point cloud data. This method involves parsing and reconstructing the topology of the guide vane's scanned measurement data file, automatically segmenting the point cloud data of the turbine guide vane, calculating the throat area of ​​the twin guide vanes, and outputting the throat area of ​​the turbine guide vane, thereby achieving automatic and accurate calculation and evaluation of the guide vane throat area. This invention also offers advantages such as high repeatability, high measurement efficiency, short measurement cycle, and avoidance of blade surface scratches.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] This invention discloses a method for calculating the throat area of ​​a guide vane based on point cloud data. The method obtains the throat area of ​​an aero-engine turbine guide vane through optical scanning measurement and point cloud processing techniques. The method includes parsing the scanned point cloud data file of the turbine guide vane and establishing its topological relationship, automatically segmenting the point cloud data of the turbine guide vane, calculating the throat area of ​​the full window and half window of the double guide vane, and outputting the throat area of ​​the guide vane, thereby achieving automatic and accurate calculation and evaluation of the throat area of ​​the guide vane.

[0007] Parsing and topological reconstruction of the turbine guide's scanned point cloud data file: The turbine guide is measured using a 3D optical scanner to obtain its scanned data file. The data file contains the distribution of coordinate points on the turbine guide surface and the description of the turbine guide surface by a triangular mesh. The topological relationship of the coordinate points is established based on the scanned data file. The topological relationship is beneficial for the automatic segmentation of the turbine guide's point cloud data and the calculation of the throat area.

[0008] The automatic segmentation of the point cloud data of the turbine guide vane: the scanning data of the turbine guide vane is segmented into point cloud data P of all adjacent double guide vanes. i and the corresponding triangulation relationship D i Where i is the sequence number of the i-th pair of split double guide vanes, then all the splitting results P i and D i The dataset O is composed of two guide vanes.

[0009] The throat area of ​​the double guide vane is calculated as follows: the minimum throat area S is calculated from the scan data of the i-th pair of double guide vanes in the vane scan dataset O. i First, a plane is constructed. The closed profile of the throat section is obtained by utilizing the intersection relationship between the plane and the triangular mesh. Then, this plane is translated and rotated to obtain different closed profiles. The area of ​​each closed profile is calculated until the minimum area is found as the throat area S of the double guide vane. i .

[0010] The output of the guide throat area: This is achieved by traversing the blade scan dataset for each pair of double guide vanes P in the O section. i and D i Calculate the corresponding minimum throat area, and finally output the minimum throat area for each pair of double guide vanes and the throat area of ​​the turbine guide vane.

[0011] As a preferred method, an optical scanning device is used to perform a three-dimensional scanning measurement of the turbine guide of the aero-engine. Then, the geometric parameters of the obtained scanning measurement data file are processed to obtain the true throat area of ​​the turbine guide. The entire measurement process does not involve any contact measurement equipment or devices. The location of the blade throat area is obtained by intersecting the spatial plane with the blade, thereby realizing the automatic, accurate, and non-contact calculation of the guide throat area.

[0012] As a preferred embodiment, the present invention discloses a method for calculating the throat area of ​​a guide based on point cloud data, comprising the following steps:

[0013] Step 1: Read the scan data file of the aircraft engine turbine guide vane using a 3D scanner, and parse it to obtain the 3D point cloud data P of the turbine guide vane.i and triangular mesh information D i Then, constructing a KD-Tree facilitates the subsequent calculation of intersection points for fast nearest neighbor retrieval.

[0014] Step 2: Based on the blade cross-section data, the point cloud data of the guide is automatically segmented into adjacent blade point cloud data that need to be evaluated using the point cloud automatic segmentation method.

[0015] The automatic point cloud segmentation method uses the parsed scan data to perform clustering and segmentation based on the cylindrical cross-sectional data of the turbine guide vane with different radii to "diffuse" a coarse segment of the entire turbine guide vane point cloud. Then, based on the leading and trailing edge angle range of the blade cross-sectional data, it further refines the segmentation to identify all adjacent twin guide vanes B. i They are combined into a double guide vane scanning dataset O, where i is the i-th pair of double guide vanes.

[0016] Step 2.1: Based on point cloud data P k =(x k y k , z k Based on the distribution of the point cloud data P, cylindrical surfaces with radii R1 and R2 are constructed according to equation (1). The cylindrical surfaces are then compared with the point cloud data P. k The intersection relationship of the triangular mesh is shown in Equation (2), which yields the cylindrical cross-sectional data C1 of the two sets of guides. i and C2 i , where P k For the k-th coordinate point in the turbine guide vane scanning point cloud data, C1 i To obtain the cylindrical cross-sectional data of the i-th blade by using the intersection of cylindrical surfaces with radius R1, C2 i To obtain the cylindrical cross-sectional data of the i-th blade by intersecting cylindrical surfaces with radius R2.

[0017] x 2 +y 2 =R 2 (1)

[0018] In formula (1), R is the radius of the cylindrical surface.

[0019]

[0020] Step 2.2: Transfer the blade cross-section data C1 i and C2 i Clustering was performed separately to obtain the blade cross-section cluster Cb1. j and Cb2 j The number of clusters j is the same as the number of blades in the guide, Cb1 j For blade section data C1 iThe j-th blade cross-section data after clustering and segmentation, Cb2 j For blade section data C2 i The cross-sectional data of the j-th blade after clustering and segmentation.

[0021] Step 2.3: According to the distance Dis of the farthest point as shown in equation (3) j Calculate Cb1 respectively j and Cb2 j Leading edge point LE1 j LE2 j and trailing edge point TE1 j TE2 j , among which, Dis j For blade section data Cb1 j or Cb2 j The farthest distance between the midpoint coordinates.

[0022]

[0023] Step 2.4: Based on Cb1 j Leading edge point LE1 j and Cb1 j+1 Leading edge point LE1 j+1 Am1, the midpoint of the arc connecting the two j Cb1 j trailing edge point TE1 j and Cb1 j+1 trailing edge point TE1 j+1 Am2, the midpoint of the arc connecting the two j Cb2 j Leading edge point LE2 j and Cb2 j+1 Leading edge point LE2 j+1 Am3, the midpoint of the arc connecting the two j Two planar cutting surfaces Pa1 are constructed on both sides of each pair of double guide vanes. j Pa2 j As shown in equation (4), the point cloud data P of the entire guide disk is... i and triangular mesh information D i The first step, coarse segmentation, is performed to obtain rough point cloud information Bc for the twin guide vanes. i .

[0024] Ax + By + Cz + D = 0 (4)

[0025] In formula (4),

[0026] A=(Am2(2)-Am1(2))*(Am3(3)-Am1(3))

[0027] -(Am2(3)-Am1(3))*(Am3(2)-Am1(2))

[0028] B=(Am3(1)-Am1(1))*(Am2(3)-Am1(3))

[0029] -(Am2(1)-Am1(1))*(Am3(3)-Am1(3))

[0030] C=(Am2(1)-Am1(1))*(Am3(2)-Am1(2))

[0031] -(Am3(1)-Am1(1))*(Am2(2)-Am1(2))

[0032] D=-(A*Am1(1)+B*Am1(2)+C*Am1(3))

[0033] Wherein, Am1, Am2, and Am3 are Am1 j Am2 j Am3 j The corresponding coordinates.

[0034] Step 2.5: Calculate the leading edge point TE1 j and trailing edge point HE1 j Angle value AngT j and AngH j Then, the coarse point cloud information Bc of the twin guide vanes is calculated. i Angle value AngBc i As shown in formula (5), for AngT j and AngH j Sort the data according to the angle range, as shown in formula (6), and then sort the coarse point cloud information Bc of the double guide vanes. i Precise segmentation is performed to obtain all adjacent double guide vanes B. i .

[0035] AngT i =arctan(TE1) i (2) / TE1 i (1))

[0036] AngH i =arctan(HE1) i (2) / HE1 i (1))

[0037] AngBc i =arctan(Bc) i (2) / Bc i (1)) (5)

[0038] AngH j ≤AngBc i ≤AngT j+1 (6)

[0039] Step 3: Calculation of throat area for double guide vanes using full-window and half-window methods based on the cross-sectional plane. First, the shortest distance at different heights of the double guide vane is calculated. Then, cubic spline interpolation is performed near the shortest distance point to re-find the shortest distance, reducing measurement errors by the 3D scanner and constructing a near-optimal initial plane. Next, the closed contour points of the throat are obtained through the intersection of the plane and the triangular facets, and the throat area is calculated. After translation and rotation of the plane, the area is recalculated to find the minimum area of ​​the double guide vane cross-section, i.e., the throat area. Double guide vane B i The throat area is the full window area of ​​the double guide vane, and the half window area is the area of ​​the two adjacent sets of double guide vanes B. i and B i+1 The area between the points is calculated using the same method as the throat area calculation for the entire window, based on the point cloud data obtained in step two.

[0040] Step 3.1: Calculate Cb1 j and Cb1 j+1 Calculate Cb2 from the coordinates of the two points S11 and S12 where the shortest distance between them lies. j and Cb2 j+1 The coordinates of the two points S21 and S22 where the shortest distance between them is found are shown in formula (7). Then, cubic spline interpolation is performed near the coordinates S11, S12, S21, and S22 to obtain S1. 1i S1 2i S2 1i S2 2i Recalculate S1 1i S1 2i The coordinates of the points where the shortest distance between them is Sc11, Sc12, calculate S2. 1i S2 2i The coordinates of the point where the shortest distance between them is Sc21, Sc22.

[0041]

[0042] Step 3.2: Construct plane Pa31 based on point coordinates Sc11, Sc12, Sc21, and intersect it with the first double guide vane B1 obtained in Step 2. Use the topological relationship of points, edges, and surfaces obtained in Step 1 to quickly find and calculate the coordinates of the intersection point between plane Pa31 and vane B1. The formula for calculating the point coordinates is shown in (8), and the contour point coordinates Ot of the cross-section plane are obtained. i Finally, the coordinates of the three-dimensional contour points Oti Convert to 2D point group label Ot2 i .

[0043]

[0044] Step 3.3: Set the coordinates of the disordered contour points Ot2 i Crust contour reconstruction was performed to obtain ordered contour point coordinates Os. i And connected end to end to form polygon g i Calculate the area of ​​polygon g using the triangle area method. i area S 11 .

[0045]

[0046] In formula (9), r is the coordinate of the ordered contour points Os i The number of.

[0047] Step 3.4: Using the line connecting any two points among the point coordinates Sc11, Sc12, and Sc21 as an axis, rotate the other point around the axis by different angles to form three new point coordinates Sc11, Sc12, and Sc21. Then, proceed with steps 3.1 to 3.3 to calculate the throat area S of the double guide vane. 2i .

[0048] Step 3.5: Based on the point coordinates Sc11, Sc12, and Sc21, rotate them around the X-axis, Y-axis, and Z-axis at different angles to form three new point coordinates Sc11, Sc12, and Sc21. Then, proceed with steps 3.1 to 3.3 to calculate the throat area S of the double guide vane. 3i .

[0049] Step 3.6: Translate plane Pa31 vertically around its normal, and simultaneously rotate it at different angles around the X, Y, and Z axes to obtain a new plane. Then, repeat the above steps to recalculate the throat area S of the double guide vane. 4i .

[0050] Step 3.7: Compare the calculated throat area S with the above calculations. 11 S 2i S 3i S 4i The minimum value is taken as the throat area S1 of this double guide vane B1.

[0051] Step 4: Traverse all double guide vanes B in the double guide vane scan dataset O. n The throat area calculation step in step three yields the full window area and half window area S of each twin guide vane. nAll laryngeal areas S n The throat area of ​​the turbine guide is obtained by adding the two values, thus realizing the automatic, accurate, and non-contact calculation of the throat area of ​​the guide.

[0052] Beneficial effects:

[0053] 1. The present invention discloses a method for calculating the throat area of ​​a guide vane based on point cloud data. The throat area obtained by constructing the intersection of a spatial plane and a double guide vane is the throat area of ​​the vane in three dimensions. It does not involve empirical formulas and is much closer to the actual throat area of ​​the guide vane during operation. Compared with the "equivalent method" for calculating the throat area, it is more accurate and saves a lot of time compared with contact measurement using mechanical devices, thus improving measurement efficiency.

[0054] 2. The present invention discloses a method for calculating the throat area of ​​a guide vane based on point cloud data. By automatically segmenting the point cloud data of the turbine guide vane from the cylindrical cross-sectional data of the blades, all adjacent double guide vane data are automatically segmented, avoiding manual operation of point cloud segmentation. The throat area of ​​the blades is calculated using the double guide vane dataset obtained in step two, thereby determining the throat area of ​​the turbine guide vane and realizing the automatic and accurate evaluation of the throat area of ​​the double blade guide vane and the turbine guide vane. Attached Figure Description

[0055] Figure 1 A flowchart of a method for calculating the throat area of ​​a guide based on point cloud data.

[0056] Figure 2 It is the partial blade data of the turbine guide vane obtained through analysis.

[0057] Figure 3 These are a pair of double guide vanes obtained by automatically segmenting the point cloud data of the turbine guide vane.

[0058] Figure 4 This is a schematic diagram showing the intersection of the constructed plane and the point cloud of the double guide vanes.

[0059] Figure 5 It is the contour point obtained by the intersection of the constructed plane and the double guide vane. Detailed Implementation

[0060] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0061] Example 1:

[0062] This embodiment discloses

[0063] The throat area of ​​a guide vane refers to the minimum flow cross-sectional area in the converging channel of a turbine guide vane. Accurately measuring the throat area is crucial for verifying and correcting the actual performance indicators of aero-engines. Due to the special complexity of blade profiles, current engineering methods for throat area measurement mainly include flow measurement, mechanical gauge methods, and coordinate measuring machines (CMMs). However, flow measurement is very complex in practice, and mechanical gauge and CMM methods have a significant problem: the measured throat area is not the true throat area, but rather a substitute for the actual throat area obtained by measuring the cold equivalent throat area at a specified location. Therefore, developing a realistic and easy-to-operate method for measuring the guide vane throat area is essential.

[0064] like Figure 1 As shown in the figure, this embodiment discloses a method for calculating the throat area of ​​a guide based on point cloud data. The specific implementation steps are as follows:

[0065] Step 1: To measure the throat area of ​​the turbine guide, a 3D optical scanner is first used to perform a 3D topographic scan of the turbine guide. After the scan is completed, the point cloud is processed into a triangular mesh to obtain triangular mesh data, and then the scan measurement data file is output.

[0066] Step 2: Read the scan data file obtained in Step 1, and obtain the point cloud data P of the turbine guide vane by parsing the file. i and triangular mesh information D i The data for the two pairs of double guide vanes (three vanes) of the guide are as follows: Figure 2 As shown, the graph contains more than 200,000 points and nearly 400,000 triangular meshes. Constructing a KD-Tree facilitates the calculation of intersection points and fast nearest neighbor retrieval.

[0067] Step 3: Perform automatic segmentation of the turbine guide vane point cloud. The parsed scan data is clustered and segmented based on the cylindrical cross-sectional data of the turbine guide vane with different radii to generate a coarse segment of the entire turbine guide vane. Then, based on the leading and trailing edge angle range of the blade cross-sectional data, all adjacent double guide vanes B are further segmented into a finer segment. i They are combined into a double guide vane scanning dataset O, where i is the i-th pair of double guide vanes.

[0068] 1) Based on point cloud data P k =(x k y k , z k Based on the distribution of the point cloud data P, construct cylindrical surfaces with radii R1 and R2 according to equation (1). k The intersection relationship of the triangular mesh is shown in Equation (2), which yields the cylindrical cross-sectional data C1 of the two sets of guides.i and C2 i , where P k Let C1 be the coordinate point in the k-th point cloud data. i To obtain the cylindrical cross-sectional data of the i-th blade by using the intersection of cylindrical surfaces with radius R1, C2 i To obtain the cylindrical cross-sectional data of the i-th blade by intersecting cylindrical surfaces with radius R2.

[0069] x 2 +y 2 =R 2 (1)

[0070] In formula (1), R is the radius of the cylindrical surface.

[0071]

[0072] 2) Transfer the blade cross-section data C1 i and C2 i Euclidean clustering was performed separately to obtain the blade section cluster Cb1. j and Cb2 j The number of clusters j is the same as the number of blades in the guide, Cb1 j For blade section data C1 i The j-th blade cross-section data after clustering and segmentation, Cb2 j For blade section data C2 i The cross-sectional data of the j-th blade after clustering and segmentation.

[0073] 3) Based on the distance Dis from the farthest point j As shown in equation (3), calculate Cb1 respectively. j and Cb2 j Leading edge point LE1 j LE2 j and trailing edge point TE1 j TE2 j , among which, Dis j For blade section data Cb1 j or Cb2 j The farthest distance between the midpoint coordinates.

[0074]

[0075] 4) Based on Cb1 j Leading edge point LE1 j and Cb1 j+1 Leading edge point LE1 j+1 Am1, the midpoint of the arc connecting the two j Cb1 j trailing edge point TE1 j and Cb1j+1 trailing edge point TE1 j+1 Am2, the midpoint of the arc connecting the two j Cb2 j Leading edge point LE2 j and Cb2 j+1 Leading edge point LE2 j+1 Am3, the midpoint of the arc connecting the two j Two planar cutting surfaces Pa1 are constructed on both sides of each pair of double guide vanes. j Pa2 j As shown in equation (4), the point cloud data P of the entire guide disk is... i and triangular mesh information D i The first step, coarse cropping, is used to obtain coarse point cloud information Bc for the twin guide vanes. i .

[0076] Ax + By + Cz + D = 0 (4)

[0077] In formula (4),

[0078] =(Am2(2)-Am1(2))*(Am3(3)-Am1(3))

[0079] -(Am2(3)-Am1(3))*(Am3(2)-Am1(2))

[0080] B=(Am3(1)-Am1(1))*(Am2(3)-Am1(3))

[0081] -(Am2(1)-Am1(1))*(Am3(3)-Am1(3))

[0082] C=(Am2(1)-Am1(1))*(Am3(2)-Am1(2))

[0083] -(Am3(1)-Am1(1))*(Am2(2)-Am1(2))

[0084] D=-(A*Am1(1)+B*Am1(2)+C*Am1(3))

[0085] Wherein, Am1, Am2, and Am3 are Am1 j Am2 j Am3 j The corresponding coordinates.

[0086] 5) Calculate the leading edge point TE1 j and trailing edge point HE1 j Angle value AngT j and AngH jThen, the coarse point cloud information Bc of the twin guide vanes is calculated. i Angle value AngBc i As shown in formula (5), for AngT j and AngH j Sort the data according to the angle range, as shown in formula (6), and then sort the coarse point cloud information Bc of the double guide vanes. i Precise segmentation is performed to obtain all adjacent double guide vanes B. i .like Figure 3 As shown in the figure, the data for a pair of double guide vanes includes coordinate point information and triangular mesh information.

[0087] AngT i =arctan(TE1) i (2) / TE1 i (1))

[0088] AngH i =arctan(HE1) i (2) / HE1 i (1))

[0089] AngBc i =arctan(Bc) i (2) / Bc i (1)) (5)

[0090] AngH j ≤AngBc i ≤AngT j+1 (6)

[0091] Step 4: Calculate the throat area of ​​the double guide vane B1, including the full window area and the half window area.

[0092] 1) Calculate Cb1 j and Cb1 j+1 Calculate Cb2 from the coordinates of the two points S11 and S12 where the shortest distance between them lies. j and Cb2 j+1 The coordinates of the two points S21 and S22 where the shortest distance between them lies are shown in formula (7). Then, cubic spline interpolation is performed between the coordinates of points S11 and S12 and between S21 and S22 to obtain S1. 1i S1 2i S2 1i S2 2i Recalculate S1 1i S1 2i The coordinates of the points where the shortest distance between them is Sc11, Sc12, calculate S2. 1i S2 2iThe coordinates of the point where the shortest distance between them is Sc21, Sc22.

[0093]

[0094] 2) Construct plane Pa31 based on point coordinates Sc11, Sc12, Sc21, and intersect it with the first double guide vane B1 obtained in step two, as shown below. Figure 4 As shown in the figure, the positional relationship between the double guide vane and the plane is described. Using the topological relationship of points, edges, and surfaces obtained in step one, the coordinates of the intersection point between plane Pa31 and blade B1 are quickly found and calculated. The formula for calculating the point coordinates is shown in (8), and the contour point coordinates Ot of the cross-section plane are obtained. i ,like Figure 5 As shown in the figure, the contour points obtained by the intersection of the plane and the double guide vanes are illustrated. Finally, the coordinates of the three-dimensional contour points Ot are... i Convert to 2D point group label Ot2 i .

[0095]

[0096] 3) Set the coordinates of the disordered contour points Ot2 i Crust contour reconstruction was performed to obtain ordered contour point coordinates Os. i And connected end to end to form polygon g i Calculate the area of ​​polygon g using the triangle area method. i area S 11 .

[0097]

[0098] In formula (9), r is the coordinate of the ordered contour points Os i The number of.

[0099] 4) Using the line connecting any two points among the point coordinates Sc11, Sc12, and Sc21 as an axis, rotate the other point around the axis by different angles to form three new point coordinates Sc11, Sc12, and Sc21. Then, perform steps 1)-3) in step four to calculate the throat area S of the double guide vane. 2i .

[0100] 5) Based on the point coordinates Sc11, Sc12, and Sc21, rotate them around the X-axis, Y-axis, and Z-axis at different angles to form three new point coordinates Sc11, Sc12, and Sc21. Then, perform steps 1)-3) in step four to calculate the throat area S of the double guide vane. 3i .

[0101] 6) Translate plane Pa31 vertically about its normal, and simultaneously rotate it at different angles about the X, Y, and Z axes to obtain a new plane. Then, repeat the above steps to recalculate the throat area S of the double guide vane. 4i .

[0102] 7) Compare the throat area S calculated above. 11 S 2i S 3i S 4i The minimum value is taken as the throat area S1 of this double guide vane B1.

[0103] Step 5: Traverse all double guide vanes B in the double guide vane scan dataset O. n The throat area S of each double guide vane is obtained by performing the throat area calculation step in step four. n All laryngeal areas S n The throat area of ​​the turbine guide is obtained by adding the values, thus realizing the automatic, accurate, and non-contact calculation of the throat area of ​​the guide.

[0104] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the throat area of ​​a guide based on point cloud data, characterized in that: The throat area of ​​the turbine guide vane of an aero-engine is obtained through optical scanning measurement and point cloud processing. The method for calculating the throat area of ​​the guide vane based on point cloud data includes parsing the scanning point cloud data file of the turbine guide vane and establishing the topological relationship, automatic segmentation of the point cloud data of the turbine guide vane, calculation of the throat area of ​​the full window and half window of the double guide vane, and output of the throat area of ​​the guide vane, thereby realizing the automatic and accurate calculation and evaluation of the throat area of ​​the guide vane. Parsing and topological reconstruction of the turbine guide's scanned point cloud data file: The turbine guide is measured using a 3D optical scanner to obtain its scanned data file. The data file contains the distribution of coordinate points on the surface of the turbine guide and the description of the turbine guide surface by a triangular mesh. The topological relationship of the coordinate points is established based on the scanned data file. The topological relationship is beneficial for the automatic segmentation of the turbine guide's point cloud data and the calculation of the throat area. The automatic segmentation of the point cloud data of the turbine guide vane: the scanning data of the turbine guide vane is segmented into point cloud data P of all adjacent double guide vanes. i and the corresponding triangulation relationship D i Where i is the sequence number of the i-th pair of split double guide vanes, then all the splitting results P i and D i The dataset O consists of two guide vanes. Calculation of the throat area of ​​the double guide vane: The minimum throat area S is calculated from the scan data of the i-th pair of double guide vanes in the vane scan dataset O. i First, a plane is constructed. The closed profile of the throat section is obtained by utilizing the intersection relationship between the plane and the triangular mesh. Then, this plane is translated and rotated to obtain different closed profiles. The area of ​​each closed profile is calculated until the minimum area is found as the throat area S of the double guide vane. i ; The output of the guide throat area: This is achieved by traversing the blade scan dataset for each pair of double guide vanes P in the O section. i and D i Calculate the corresponding minimum throat area, and finally output the minimum throat area for each pair of double guide vanes and the throat area of ​​the turbine guide vane. The calculation method includes the following steps. Step 1: Read the scan data file of the aircraft engine turbine guide vane using a 3D scanner, and parse it to obtain the 3D point cloud data P of the turbine guide vane. i and triangular mesh information D i Then, constructing a KD-Tree facilitates the calculation of intersection points and fast nearest neighbor retrieval later; Step 2: Based on the blade cross-section data, the point cloud data of the guide is automatically segmented into adjacent blade point cloud data that need to be evaluated using the point cloud automatic segmentation method; The automatic point cloud segmentation method uses the parsed scan data to perform clustering and "diffraction" on the cylindrical cross-sectional data of the turbine guide vane with different radii to obtain a coarse segment of the entire turbine guide vane point cloud. Then, it further refines the segmentation based on the leading and trailing edge angle range of the blade cross-sectional data to identify all adjacent twin guide vanes B. i , and combine them into a double guide vane scanning dataset O, where i is the i-th pair of double guide vanes; Step 2.1: Based on point cloud data P k =(x k ,y k ,z k Based on the distribution of the point cloud data P, cylindrical surfaces with radii R1 and R2 are constructed according to equation (1). The cylindrical surfaces are then compared with the point cloud data P. k The intersection relationship of the triangular mesh is shown in Equation (2), which yields the cylindrical cross-sectional data C1 of the two sets of guides. i and C2 i , where P k For the k-th coordinate point in the turbine guide vane scanning point cloud data, C1 i To obtain the cylindrical cross-sectional data of the i-th blade by using the intersection of cylindrical surfaces with radius R1, C2 i To obtain the cylindrical cross-sectional data of the i-th blade by using the intersection of cylindrical surfaces with radius R2; x 2 +y 2 =R 2 (1) In formula (1), R is the radius of the cylindrical surface; Step 2.2: Transfer the blade cross-section data C1 i and C2 i Clustering was performed separately to obtain the blade cross-section cluster Cb1. j and Cb2 j The number of clusters j is the same as the number of blades in the guide, Cb1 j For blade section data C1 i The j-th blade cross-section data after clustering and segmentation, Cb2 j For blade section data C2 i The cross-sectional data of the j-th blade after clustering and segmentation; Step 2.3: According to the distance Dis of the farthest point as shown in equation (3) j Calculate Cb1 respectively j and C b2 j Leading edge point LE1 j LE2 j and trailing edge point TE1 j TE2 j , among which, Dis j For blade section data Cb1 j or Cb2 j The farthest distance between the midpoint coordinates; Step 2.4: Based on Cb1 j Leading edge point LE1 j and Cb1 j+1 Leading edge point LE1 j+1 Am1, the midpoint of the arc connecting the two j Cb1 j trailing edge point TE1 j and Cb1 j+1 trailing edge point TE1 j+1 Am2, the midpoint of the arc connecting the two j Cb2 j Leading edge point LE2 j and Cb2 j+1 Leading edge point LE2 j+1 Am3, the midpoint of the arc connecting the two j Two planar cutting surfaces Pa1 are constructed on both sides of each pair of double guide vanes. j Pa2 j As shown in equation (4), the point cloud data P of the entire guide disk is... i and triangular mesh information D i The first step, coarse segmentation, is performed to obtain rough point cloud information Bc for the twin guide vanes. i ; Ax + By + Cz + D = 0 (4) In formula (4), A=(Am2(2)-Am1(2))*(Am3(3)-Am1(3)) -(Am2(3)-Am1(3))*(Am3(2)-Am1(2)) B=(Am3(1)-Am1(1))*(Am2(3)-Am1(3)) -(Am2(1)-Am1(1))*(Am3(3)-Am1(3)) C=(Am2(1)-Am1(1))*(Am3(2)-Am1(2)) -(Am3(1)-Am1(1))*(Am2(2)-Am1(2)) D=-(A*Am1(1)+B*Am1(2)+C*Am1(3)) Wherein, Am1, Am2, and Am3 are Am1 j Am2 j Am3 j The corresponding coordinates; Step 2.5: Calculate the leading edge point LE1 j and trailing edge point TE1 j Angle value AngT j and AngH j Then, the coarse point cloud information Bc of the twin guide vanes is calculated. i Angle value AngBc i As shown in formula (5), for AngT j and AngH j Sort the data according to angle range, as shown in formula (6), and then sort the coarse point cloud information Bc of the double guide vanes. i Precise segmentation is performed to obtain all adjacent double guide vanes B. i ; AngT i =arc tan(TE1 i (2) / TE1 i (1)) Avg L i =arc tan(LE1 j (2) / LE1 i (1)) AngBc i =arc tan(Bc i (2) / B c i (1))(5) The T j ≤TheBc i ≤The L j+1 (6) Step 3: A method for calculating the throat area of ​​a double-guided blade using full-window and half-window methods based on a cross-sectional plane. First, the shortest distance at different heights of the double-guided blade is calculated. Then, cubic spline interpolation is performed near the shortest distance point to re-find the shortest distance, reducing measurement errors by the 3D scanner and constructing a near-optimal initial plane. Next, the closed contour points of the throat are obtained through the intersection of the plane and the triangular facets, and the throat area is calculated. After translation and rotation of the plane, the area is recalculated to find the minimum area of ​​the double-guided blade cross-section, i.e., the throat area. (Double-guided blade B) i The throat area is the full window area of ​​the double guide vane, and the half window area is the area of ​​the two adjacent sets of double guide vanes B. i and B i+1 The area between them is calculated using the same method as the throat area calculation for the full window, based on the point cloud data obtained in step two. Step 3.1: Calculate Cb1 j and Cb1 j+1 Calculate Cb2 from the coordinates of the two points S11 and S12 where the shortest distance between them lies. j and Cb2 j+1 The coordinates of the two points S21 and S22 where the shortest distance between them is found are shown in formula (7). Then, cubic spline interpolation is performed near the coordinates S11, S12, S21, and S22 to obtain S1. 1i S1 2i S2 1i S2 2i Recalculate S1 1i S1 2i The coordinates of the points where the shortest distance between them is Sc11, Sc12, calculate S2. 1i S2 2i The coordinates of the point where the shortest distance between them is Sc21, Sc22; Step 3.2: Construct plane Pa31 based on point coordinates Sc11, Sc12, Sc21, and intersect it with the first double guide vane B1 obtained in Step 2. Use the topological relationship of points, edges, and surfaces obtained in Step 1 to quickly find and calculate the coordinates of the intersection point between plane Pa31 and vane B1. The formula for calculating the point coordinates is shown in (8), and the contour point coordinates Ot of the cross-section plane are obtained. i Finally, the coordinates of the three-dimensional contour points Ot i Convert to 2D point coordinates Ot2 i ; Step 3.3: Set the coordinates of the disordered contour points Ot2 i Crust contour reconstruction was performed to obtain ordered contour point coordinates Os. i And connected end to end to form polygon g i Calculate the area of ​​polygon g using the triangle area method. i area S 11 ; In formula (9), r is the coordinate of the ordered contour points Os i The number of; Step 3.4: Using the line connecting any two points among the point coordinates Sc11, Sc12, and Sc21 as an axis, rotate the other point around the axis by different angles to form three new point coordinates Sc11, Sc12, and Sc21. Then, proceed with steps 3.1 to 3.3 to calculate the throat area S of the double guide vane. 2i ; Step 3.5: Based on the point coordinates Sc11, Sc12, and Sc21, rotate them around the X-axis, Y-axis, and Z-axis at different angles to form three new point coordinates Sc11, Sc12, and Sc21. Then, proceed with steps 3.1 to 3.3 to calculate the throat area S of the double guide vane. 3i ; Step 3.6: Translate plane P a31 vertically around its normal, and simultaneously rotate it at different angles around the X, Y, and Z axes to obtain a new plane. Then, repeat the above steps to recalculate the throat area S of the double guide vane. 4i ; Step 3.7: Compare the calculated laryngeal area S 11 S 2i S 3i S 4i The minimum value is taken as the throat area S1 of this double guide vane B1; Step 4: Traverse all double guide vanes B in the double guide vane scan dataset O. n The throat area calculation step in step three yields the full window area and half window area S of each twin guide vane. n All laryngeal areas S n The throat area of ​​the turbine guide is obtained by adding the two values, thus realizing the automatic, accurate, and non-contact calculation of the throat area of ​​the guide.

2. The method for calculating the throat area of ​​a guide based on point cloud data as described in claim 1, characterized in that: The turbine guide vane of an aero-engine is three-dimensionally scanned and measured using optical scanning equipment. The resulting scan measurement data file is then processed to obtain the true throat area of ​​the turbine guide vane. The entire measurement process is conducted without the involvement of any contact measurement equipment or devices. The location of the blade throat area is found by intersecting the spatial plane with the blade, thus achieving automatic, accurate, and non-contact calculation of the guide vane throat area.

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