A method and device for identifying the geometric features of blade profiles

Abstract

The present invention relates to a method and device for identifying the geometric characteristics of blade profiles. The method includes: obtaining a set of profile points; dividing the set of profile points according to the maximum distance; respectively interpolating the divided point sets into B-spline curves C cc and C cv ; respectively taking the parameters of curves C cc and C cv , calculating the profile points, and constructing normal lines; constructing the objective function and constraint function for the minimum distance from the mid-arc point P cb on the normal line to curves C cc and C cv ; solving the objective function by an optimization method to obtain the suction surface sequence {P} cc , the mid-arc sequence {P} cb and the pressure surface sequence {P} cv ; determining the profile characteristic points and profile lines according to the definitions. The present invention identifies the geometric characteristics of blade profiles by combining the mid-arc definition with the B-spline characteristics, has high calculation accuracy, and can effectively improve the automation degree of blade profile geometric characteristic identification; the method proposed by the present invention can be implemented on any CAD / CAM platform or by independently writing software algorithms, and has strong versatility.

Description

Technical Field

[0001] The present invention belongs to the field of computer-aided design and manufacturing, and relates to a method and device for identifying geometric features of blade profiles. Background Art

[0002] Blades are core components of aeroengines, and their geometric shapes and machining accuracies have a great impact on the performance of aeroengines. In the fields of reverse blade modeling, manufacturing, and inspection and evaluation, the identification of blade profile feature points and profile lines plays an important role.

[0003] Currently, the commonly used methods for blade profile geometric features mainly include the convex hull iteration method and the isometric line self-intersection method. The convex hull iteration method applies two-dimensional convex hull iteration to solve and extract profile feature parameters based on the principle that the distances from the incenter to the tangent points on the blade concave and convex surfaces are equal. The calculation accuracy is relatively high, but the iteration time consumption is serious. When using the method of layer-by-layer subdivision and intersection of isometric lines, the determination and sorting of singular points result in low efficiency and large calculation errors. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] Embodiments of the present invention provide a method and device for identifying geometric features of blade profiles, which can automatically identify various key profile features. It has the advantages of high automation, high calculation efficiency, strong stability, etc., and solves the above-mentioned technical problems existing in the identification of existing blade profile geometric features.

[0006] (2) Technical Solutions

[0007] In a first aspect, an embodiment of the present invention proposes a method for identifying geometric features of blade profiles, including:

[0008] Obtaining a profile point set;

[0009] Dividing the profile point set according to the maximum distance;

[0010] Interpolating the divided point sets into B-spline curves C cc and C cv ;

[0011] Respectively taking the parameters of curves C cc and C cv , calculating the profile points, and constructing normal lines;

[0012] Constructing the objective function and constraint function of the minimum distance from the mid-arc point P cb on the normal line to curves C cc and C cv ;

[0013] Solving the objective function by an optimization method to obtain the blade concave sequence {P}cc , the middle arc sequence {P} cb and the back leaf sequence {P} cv ;

[0014] Determine the airfoil characteristic points and the airfoil line according to the definition.

[0015] In a second aspect, there is provided an apparatus for identifying the geometric characteristics of a blade airfoil, including:

[0016] An acquisition module for acquiring an airfoil point set;

[0017] A segmentation module for segmenting the airfoil point set according to the maximum distance;

[0018] An interpolation module for interpolating the segmented point sets into B-spline curves C cc and C cv ;

[0019] A calculation module for respectively taking the parameters of curves C cc and C cv to calculate the profile points and construct a normal line;

[0020] A construction module for constructing an objective function and a constraint function for the minimum distance from the middle arc point P cb on the normal line to curves C cc and C cv ;

[0021] A solution module for solving the objective function by an optimization method to obtain the leaf basin sequence {P} cc , the middle arc sequence {P} cb and the back leaf sequence {P} cv ;

[0022] A determination module for determining the airfoil characteristic points and the airfoil line according to the definition.

[0023] In a third aspect, there is provided a terminal device, including:

[0024] A processor; and

[0025] A memory storing executable code which, when executed by the processor, causes the processor to execute the method as described above.

[0026] In a fourth aspect, there is provided a non-transitory machine-readable storage medium storing executable code which, when executed by a processor of an electronic device, causes the processor to execute the method as described above.

[0027] (3) Advantageous effects

[0028] In summary, the present invention identifies the geometric features of the blade profile based on the definition of the mean camber line and the characteristics of B-spline, with high calculation accuracy and can effectively improve the automation degree of identifying the geometric features of the blade profile; the method proposed by the present invention can be implemented on any CAD / CAM platform or by independently writing software algorithms, with strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 is a flowchart showing a method for identifying the geometric features of a blade profile according to an embodiment of the present invention.

[0031] Figure 2 is an illustration of key points and profile lines of the blade profile.

[0032] Figure 3 is the relationship between the points on the mean camber line and the points on the suction side and pressure side of the blade.

[0033] Figure 4 is the relationship between the arc points and the arc center.

[0034] Figure 5 is the relationship between the mean camber line, the arc and the leading edge points. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will further describe in detail the embodiments of the present invention in conjunction with the drawings and embodiments. The following detailed description and drawings are used to exemplarily illustrate the principle of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modifications, replacements and improvements of parts, components and connection methods without departing from the spirit of the present invention.

[0036] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail the present application.

[0037] The present invention provides a calculation method for automatically identifying the geometric features of a blade profile using the equidistant characteristics of the mean camber line, which can automatically identify key features of the blade profile such as the leading edge points, leading edge arcs, leading edge tangent points, trailing edge points, trailing edge arcs, trailing edge tangent points, suction side profile lines, pressure side profile lines and mean camber lines (as Figure 2 shown). It has the advantages of high automation degree, high calculation efficiency and strong stability.

[0038] Figure 1 This is a schematic flowchart of a method for identifying the geometric features of blade profiles provided by an embodiment of the present invention. As Figure 1 shown, the method includes:

[0039] S1. Obtain a profile point set;

[0040] In this step, set a blade cross-section S and obtain an ordered point set {P i} i＝0～n on the cross-section of the blade profile. Specifically, for the reverse and measurement processes, set an error ε and calculate the points P' j whose distance from the point cloud to the cross-section S is less than the error ε. Then calculate the projection points P j of the points P' i onto the cross-section S to obtain the ordered point set {P i}; if it is to identify the profile features of the blade digital model S i＝0～n , calculate the intersection points of the cross-section S and S b to obtain the ordered point set {P b} i . i＝0～n .

[0041] S2. Divide the profile point set according to the maximum distance;

[0042] The specific process of this step is as follows:

[0043] Traverse the point set {P i}, and calculate the two points P j and P k with the farthest distance among them;

[0044] Use the points P j and P k to divide the point set {P i} to obtain the point sets {P j,k} = {P k ,.P k+1 ,..,P n-1 ,P n ,P 0 ,P 1 ,...,P j-1 ,P j} and {P k,j} = {P j ,..P k};

[0045] S3. Interpolate the divided point sets into B-spline curves C cc and C cv respectively;

[0046] In this step, interpolate the point sets {P j,k} and {Pk,j} are respectively interpolated into B-spline curves C cc (u) and C cv (v);

[0047] S4. Respectively take the parameters of curves C cc and C cv to calculate the control points and construct the normal lines;

[0048] In this step, the specific process of calculating using the parameters of curve C cc is as follows:

[0049] Traverse the parameter knot sequence of curve C cc to calculate the minimum interval Δu, and calculate the integer N = int(1 / Δu), where int() is the rounding operation;

[0050] Uniformly insert N parameters equidistantly in the parameter sequence {0, 1} to obtain the parameter sequence {u i}; i＝0～N+1

[0051] Traverse the parameter sequence {u i}, and calculate the control point P cc of curve C i at parameter u cc , the first-order differential and the second-order differential and then calculate the normal vector n;

[0052] Judge the direction of the normal vector n. If it points to curve C cv , then go to the next step; if it deviates from curve C cv , then the normal vector n takes the reverse direction;

[0053] Draw a straight line L starting from point P cc in the direction of the normal vector n;

[0054] Calculate the intersection point Q of the straight line L and curve C cv ;

[0055] Set the starting points of the straight line L to P cc and Q respectively, and interpolate them into a B-spline curve L(s).

[0056] The process of calculating using the parameters of curve C cv is similar and will not be elaborated here.

[0057] S5. Construct the objective function and constraint function for the minimum distance from the mid-arc point P cb on the normal line to curves C cc and C cv ;

[0058] Such as Figure 3As shown, according to the definition of the mean camber line, the point P on the mean camber line cb has the same distance to the blade suction surface and the blade pressure surface, the point P cb is on the straight line L, the vector from the point P cv to the point P cb is perpendicular to the curve C cc . Set the objective function and the constraint function:

[0059] F(v, s) = ||P cc - P cb || 2 - ||P cv - P cb || 2 = 0 (1)

[0060]

[0061] In the formula, P cv is the point on the curve C cc , is the first-order differential of the point P cv , · is the vector dot product calculation;

[0062] S6. Solve the objective function by the optimization method to obtain the blade suction surface sequence {P} cc , the mean camber line sequence {P} cb and the blade pressure surface sequence {P} cv ;

[0063] Still taking the curve C cc (u) as an example to illustrate, according to the formulas (1) and (2), establish the augmented Lagrange function:

[0064]

[0065] Use the iterative optimization algorithm to solve the formula (3). If there is a solution and the parameters 0 < v < 1, 0 < s < 1, store the point P cc and the point P cb into the blade suction surface sequence {P} cc and the mean camber line sequence {P} cb respectively; if there is no solution, skip the current parameter u i ;

[0066] Repeat the above steps until the parameter sequence {u i} is traversed;

[0067] Calculate the mean camber line sequence {P} cv and the blade pressure surface sequence {P} cb through the curve C cv , and the specific process is the same as that of the curve C cc(u) Similarly, it will not be elaborated here. The mid-arc sequences {P} obtained from the two calculations cb are merged to finally obtain the blade pressure surface sequence {P} cc , the mid-arc sequence {P} cb and the blade suction surface sequence {P} cv .

[0068] S7. Determine the airfoil characteristic points and profile lines according to the definitions.

[0069] The specific process of this step is as follows:

[0070] Interpolate the mid-arc sequence {P} cb into a B-spline curve C cb (t), and calculate its endpoints C cb (0) and C cb (1);

[0071] Set the maximum allowable error ε, and traverse the parameter sequences of the blade pressure surface sequence {P} cc and the blade suction surface sequence {P} cv , as Figure 4 shown. According to the definition of a circular arc, the tangent of a point on the circular arc is perpendicular to the line from the point to the center of the circle. Establish a leading and trailing edge circular arc point judgment function:

[0072]

[0073] Judge the leading and trailing edge points according to Equation (4). Store the points closer to point C cb (0) into the leading edge circular arc sequence {P} le , and store the points closer to point C cb (1) into the trailing edge circular arc sequence {P} te ;

[0074] The relationship among the mid-arc, circular arc, and leading edge points is as Figure 5 shown. Calculate the distances R le from the leading edge circular arc sequence {P} cb (0) to point C le , and the distances R te from the trailing edge circular arc sequence {P} cb (1) to point C te . If R le > R te , then the leading edge circular arc sequence {P} le and the trailing edge circular arc sequence {P} te are interchanged;

[0075] In the blade pressure surface sequence {P} cc and the blade suction surface sequence {P} cv , the parts corresponding to the leading edge circular arc sequence {P} le and the trailing edge circular arc sequence {P} teRemoval of duplicate points;

[0076] Traverse the pressure side sequence {P} cc and the suction side sequence {P} cv respectively, and calculate the sum of the distances D between two adjacent points before and after cc and D cv If D cc > D cv then swap the pressure side sequence {P} cc and the suction side sequence {P} cv ;

[0077] Arrange the pressure side sequence {P} cc , the suction side sequence {P} cv , the leading edge arc sequence {P} le and the trailing edge arc sequence {P} te in the same clockwise or counterclockwise direction, and interpolate them into the pressure side profile C cc , the suction side profile C cv , the leading edge arc C le , the trailing edge arc C te ;

[0078] Adjust the direction of the mean camber line sequence {P} cb and the mean camber line C cb so that the endpoints with parameter t = 0 are close to the leading edge. At this time, the endpoints are the center points P of the leading edge arc le c and the center points P of the trailing edge arc te c ;

[0079] Calculate the intersection points of the tangent lines at the endpoints of the mean camber line C cb with the leading edge arc C le and the trailing edge arc C te . The intersection points are the leading edge point P le and the trailing edge point P te ;

[0080] Take the first and last points of the leading edge arc sequence {P} le and the trailing edge arc sequence {P} te . According to the distances closest to the first and last points of the pressure side sequence {P} cc and the suction side sequence {P} cv , judge the leading edge tangent points P with the pressure side le cc , the leading edge tangent points P with the suction side le cv , the trailing edge tangent points P with the pressure side te cc , the trailing edge tangent points P with the suction side te cv .

[0081] The finally recognized key points and profile lines of the blade profile are as Figure 2 shown.

[0082] In a second aspect, there is provided an apparatus for identifying geometric features of a blade profile, including:

[0083] An acquisition module for acquiring a set of profile points;

[0084] A segmentation module for segmenting the set of profile points according to the maximum distance;

[0085] An interpolation module for interpolating the segmented point sets into B-spline curves C cc and C cv respectively;

[0086] A calculation module for respectively taking the parameters of curves C cc and C cv to calculate profile value points and construct normal lines;

[0087] A construction module for constructing an objective function and a constraint function for the minimum distance from the mid-arc point P cb on the normal line to curves C cc and C cv respectively;

[0088] A solution module for solving the objective function by an optimization method to obtain a leading-edge sequence {P} cc , a mid-arc sequence {P} cb and a trailing-edge sequence {P} cv respectively;

[0089] A determination module for determining blade profile feature points and profile lines according to definitions.

[0090] In a third aspect, there is provided a terminal device, including:

[0091] A processor; and

[0092] A memory storing executable code thereon, which when executed by the processor, causes the processor to execute the method as described above.

[0093] In a fourth aspect, there is provided a non-transitory machine-readable storage medium storing executable code thereon, which when executed by a processor of an electronic device, causes the processor to execute the method as described above.

[0094] The above are only embodiments of the present application and do not limit the present application. For those skilled in the art, various changes and modifications can be made to the present application without departing from the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for identifying the geometric features of a blade profile, characterized in that, it includes: obtaining a set of profile points; dividing the set of profile points according to the maximum distance; Interpolate the separately segmented point sets into B-spline curves C cc and C cv ; Respectively take the parameters of curve C cc and C cv to calculate the profile points and construct the normal line; Construct the mid-arc point P on the normal line cb to curve C cc and C cv The objective function and constraint function of the minimum distance Solving the objective function by an optimization method to obtain the blade pressure surface sequence {P} cc , the mean camber line sequence {P} cb and the blade suction surface sequence {P} cv ; determining profile feature points and profile lines according to the definition; Among them, taking the curve C cc The specific process of parameter calculation is as follows: Traverse the curve C cc of the parametric node sequence, calculate the minimum interval Δu, and calculate the integer N = int(1 / Δu), where int() is the rounding operation; Insert N parameters equidistantly and uniformly into the parameter sequence {0, 1} to obtain the parameter sequence {u i} i＝0～N+1 Traverse the parameter sequence {u i}, and calculate the curve C cc At the parameter u i to obtain the value point P cc , the first-order differential and the second-order differential Furthermore, calculate the normal vector n; Judge the direction of the normal vector n. If it points to the curve C cv , then go to the next step; if it deviates from the curve C cv , then reverse the normal vector n. Construct a straight line L starting from point P cc and with the normal vector n as the direction; Calculate the intersection point Q of the straight line L and the curve C cv ; Set the starting points of the straight line L as P cc and Q respectively, and interpolate to a B-spline curve L(s).

2. The method according to claim 1, characterized in that, the obtaining of the set of profile points specifically includes: For the reverse and measurement processes, set the error ε, and calculate the points P' whose distances from the point cloud to the cross-section S are less than the error ε j , and then calculate the points P' j and the projection points P i to the cross-section S, obtaining an ordered point set {P i} i＝0～n ; For the airfoil characteristics of the identified blade digital model S b , the intersection points of section S and S b are calculated to obtain an ordered point set {P i} i＝0～n .

3. The method according to claim 1, characterized in that, the dividing of the set of profile points according to the maximum distance specifically includes: Traverse the set of blade profile points {P i}, and calculate the two points P j and P k with the farthest distance from each other; Use point P j and P k to divide the point set {P i}, obtaining the point sets {P j,k} = {P k ,.P k+1 ,..,P n-1 ,P n ,P 0 ,P 1 ,...,P j-1 ,P j} and {P k,j} = {P j ,..P k}.

4. The method according to claim 1, characterized in that, the determining of profile feature points and profile lines according to the definition specifically includes: Interpolate the mid-arc sequence {P} cb into a B-spline curve C cb (t), and calculate its endpoints C cb (0) and C cb (1); Set the maximum allowable error ε and traverse the parameter sequences, i.e., the blade pressure surface sequence {P} cc and the blade suction surface sequence {P} cv , according to the definition of a circular arc, the tangent of a point on the circular arc is perpendicular to the line connecting the point to the center of the circle. Establish a function for judging the points on the leading and trailing edge circular arcs: where P cv is a point on curve C cc , is the first-order differential of point P cv , and · represents the vector dot product calculation; Based on the above-mentioned leading and trailing edge arc point judgment function, perform the judgment of the leading and trailing edge points, and store the points close to point C cb (0) into the leading edge arc sequence {P} le , and store the points close to point C cb (1) into the trailing edge arc sequence {P} te ; Calculate the distances R of the leading-edge arc sequence {P} le to point C cb (0), the distances R of the trailing-edge arc sequence {P} le to point C te (1). If R cb >R te , then swap the leading-edge arc sequence {P} le with the trailing-edge arc sequence {P} te . le te ;​ Remove the points that are repeated in the leaf basin sequence {P} cc and the leaf back sequence {P} cv where the leading edge circular arc sequence {P} le and the trailing edge circular arc sequence {P} te are repeated; Traverse the leaf basin sequence {P} and cc the leaf back sequence {P} respectively, cv calculate the sum of the distances D between two adjacent points before and after, cc and D, cv if D cc > D cv , then swap the leaf basin sequence {P} cc and the leaf back sequence {P}; cv ​ Arrange the blade pressure surface sequence {P} cc , the blade suction surface sequence {P} cv , the leading edge circular arc sequence {P} le and the trailing edge circular arc sequence {P} te in the same clockwise or counterclockwise direction, and interpolate them into the blade pressure surface curve C cc , the blade suction surface curve C cv , the leading edge circular arc C le , the trailing edge circular arc C te ; Adjust the mid-arc sequence {P} cb and the direction of the mid-arc C cb so that the endpoints where the parameter t = 0 are close to the leading edge, and the endpoints are the center points P le c of the leading-edge circular arc and the center point P te c ; Calculating the mean camber line C cb The intersection points of the end tangent line with the leading-edge arc C le , and the trailing-edge arc C te are the leading-edge point P le and the trailing-edge point P te ; Take the leading-edge arc sequence {P} le and the trailing-edge arc sequence {P} te starting and ending points, and according to the distance closest to the leading-edge arc sequence {P} cc and the suction-side arc sequence {P} cv starting and ending points, determine the tangent points P of the leading edge and the suction side le cc , the tangent points P of the leading edge and the pressure side le cv , the tangent points P of the trailing edge and the suction side te cc , the tangent points P of the trailing edge and the pressure side te cv .

5. A device for identifying the geometric features of a blade profile, characterized in that, it includes: an obtaining module for obtaining a set of profile points; a dividing module for dividing the set of profile points according to the maximum distance; An interpolation module for interpolating the respectively segmented point sets into B-spline curves C cc and C cv ; A calculation module for separately obtaining the parameters of curve C cc and C cv to calculate the profile points and construct the normal line; A building block for building the mid-arc point P on the normal line cb to curve C cc and C cv The objective function and constraint function for the minimum distance A solution module, which is used to solve the objective function by an optimization method to obtain a blade suction surface sequence {P} cc , a mean camber line sequence {P} cb and a blade pressure surface sequence {P} cv ; a determining module for determining profile feature points and profile lines according to the definition; Among them, taking the curve C cc The specific process of parameter calculation is as follows: Traverse the curve C cc of the parametric node sequence, calculate the minimum interval Δu, and calculate the integer N = int(1 / Δu), where int() is the rounding operation; Insert N parameters equidistantly and uniformly into the parameter sequence {0, 1} to obtain the parameter sequence {u i} i＝0～N+1 Traverse the parameter sequence {u i}, and calculate the curve C cc at the parameter u i to obtain the value point P cc , the first-order differential and the second-order differential and then calculate the normal vector n; Judge the direction of the normal vector n. If it points to the curve C cv , then go to the next step; if it deviates from the curve C cv , then reverse the normal vector n. Construct a straight line L starting from point P cc and with the normal vector n as the direction; Calculate the intersection point Q of the straight line L and the curve C cv ; Set the starting points of the straight line L as P cc and Q respectively, and interpolate to a B-spline curve L(s).

6. The device according to claim 5, characterized in that, the obtaining module is specifically used for: For the reverse and measurement processes, set the error ε, and calculate the points P' whose distances from the point cloud to the cross-section S are less than the error ε j , and then calculate the points P' j and the projection points P i to the cross-section S, obtaining an ordered point set {P i} i＝0～n ; For the airfoil characteristics of the identified blade digital model S b the intersection points of section S and S b are calculated to obtain an ordered point set {P i} i＝0～n .

7. The device according to claim 5, characterized in that, the dividing module is specifically used for: Traverse the set of blade profile points {P i}, and calculate the two points P j and P k with the farthest distance among them; Using point P j and P k to divide the point set {P i}, obtaining the point sets {P j,k} = {P k ,.P k+1 ,..,P n-1 ,P n ,P 0 ,P 1 ,...,P j-1 ,P j} and {P k,j} = {P j ,..P k}.

8. The device according to claim 5, characterized in that, the determining module is specifically used for: Interpolate the mid-arc sequence {P} cb into a B-spline curve C cb (t), and calculate its end points C cb (0) and C cb (1); Set the maximum allowable error ε and traverse the parameter sequences, the blade pressure surface sequence {P} cc and the blade suction surface sequence {P} cv , according to the definition of an arc, the tangent of a point on the arc is perpendicular to the line from the point to the center of the circle. Establish a function for judging the leading and trailing edge arc points: where P cv is a point on curve C cc , is the first-order differential of point P cv , and · represents the vector dot product calculation; Judging the leading and trailing edge points according to the above-mentioned leading and trailing edge arc point judgment function, and storing the points close to point C cb (0) into the leading edge arc sequence {P} le , and storing the points close to point C cb (1) into the trailing edge arc sequence {P} te ; Calculate the distances of the leading-edge arc sequence {P} le to point C cb (0) as R le and the distances of the trailing-edge arc sequence {P} te to point C cb (1) as R te If R le > R te then swap the leading-edge arc sequence {P} le with the trailing-edge arc sequence {P} te ; Remove the points that are repeated in the leaf basin sequence {P} cc and the leaf back sequence {P} cv in the leading edge circular arc sequence {P} le and the trailing edge circular arc sequence {P} te ​ Traverse the leaf basin sequence {P} and cc the leaf back sequence {P} respectively, cv calculate the sum of the distances D between two adjacent points before and after, cc and D cv , if D cc > D cv , then swap the leaf basin sequence {P} cc and the leaf back sequence {P} cv ; Arrange the blade pressure surface sequence {P} cc , the blade suction surface sequence {P} cv , the leading edge arc sequence {P} le and the trailing edge arc sequence {P} te in the same clockwise or counterclockwise direction, and interpolate them into the blade pressure surface profile C cc , the blade suction surface profile C cv , the leading edge arc C le , the trailing edge arc C te ; Adjust the sequence of mid - arcs {P} cb and the direction of the mid - arc C cb so that the endpoints with parameter t = 0 are close to the leading edge. At this time, the endpoints are the center points P le c of the leading - edge circular arc and P te c ; Calculate the mean camber line C cb The intersection points of the end tangent lines with the leading edge arc C le , the trailing edge arc C te are the intersection points, which are the leading edge point P le and the trailing edge point P te ; Take the leading-edge arc sequence {P} le and the trailing-edge arc sequence {P} te starting and ending points, and according to the sequence {P} closest to the blade pressure surface cc and the blade suction surface sequence {P} cv starting and ending points, judge the leading-edge and blade pressure surface tangent point P le cc and the leading-edge and blade suction surface tangent point P le cv and the trailing-edge and blade pressure surface tangent point P te cc and the trailing-edge and blade suction surface tangent point P te cv .

9. A terminal device, characterized in that, it includes: a processor; and a memory storing executable code, which when executed by the processor, causes the processor to execute the method according to any one of claims 1-4.

10. A non-transitory machine-readable storage medium storing executable code, characterized in that, when the executable code is executed by a processor of an electronic device, it causes the processor to execute the method according to any one of claims 1-4.

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