Two-dimensional blade modeling method, blade optimization method and two-dimensional blade profile

Abstract

The present invention provides a two-dimensional blade profile modeling method, including: obtaining an initial blade profile thickness distribution curve, determining a point P1 located below the initial leading edge point; determining a point P4 on the initial suction surface thickness distribution curve, taking P1 and P4 as the starting point and the end point, constructing a third-order Bezier curve, and connecting it with the initial blade body suction surface thickness distribution curve to form a new suction surface thickness distribution curve, so that the first-order derivative and the second-order derivative are continuous at P4 and the tangent vector is vertical at P1; also constructing a new pressure surface thickness distribution curve to form a new blade profile thickness distribution curve; superimposing the new blade profile thickness distribution curve on the mid-arc line to obtain a new two-dimensional blade profile. The present invention also provides a blade optimization method for constructing a two-dimensional blade profile using the above-mentioned two-dimensional blade profile modeling method. The present invention also provides a two-dimensional blade profile constructed by the above-mentioned two-dimensional blade profile modeling method. The above-mentioned two-dimensional blade profile modeling method can achieve an improvement in blade performance at a relatively low cost.

Description

Technical Field

[0001] The present invention relates to a two-dimensional blade profile modeling method, a blade optimization method for constructing a two-dimensional blade profile using the two-dimensional blade profile modeling method to optimize the blade, and a two-dimensional blade profile constructed by the two-dimensional blade profile modeling method. Background Art

[0002] Aircraft engine blades are the basic units that make up the compressor / turbine. The flow path formed by adjacent blades determines the performance of the engine, so the blades play a decisive role in the performance of the compressor / turbine. Aircraft engine blades have the characteristics of complex blade profiles, large blade body twisting curvature, thin blade body, and high geometric accuracy requirements. Designers decouple the three-dimensional blade design into a series of two-dimensional flow surface blade design problems distributed along the blade height. Through two-dimensional blade design and three-dimensional stacking, the three-dimensional blade design results are generated. The design constraints are given by the flow design (streamline), including parameters such as inlet and outlet airflow angles, inlet Mach number, axial speed, etc., which gradually change along the blade height direction.

[0003] Under different working conditions, the blade inlet angle of attack will change significantly. For example, near the breathing point, the blade will be in a positive angle of attack state, while near the blocking point, the blade angle of attack is negative. How to ensure that the blade does not make a large adjustment, through the local adjustment of the leading edge profile of the blade, to ensure that the blade loss is reduced as much as possible within the widest possible angle of attack range and to increase the blade profile angle of attack range is a difficult problem that needs to be solved urgently.

[0004] The current conventional design method for two-dimensional blade profiles is to generate a two-dimensional blade profile by superimposing the thickness distribution along the normal direction of the median arc line, in which the thickness of the suction surface and the pressure surface are symmetrically distributed, and the leading edge is a circle or an ellipse. If the profile line near the leading edge needs to be adjusted, the median arc line and the thickness distribution curve need to be updated, resulting in a more obvious change in the geometric profile of the blade body.

[0005] The present invention aims to provide a two-dimensional blade shaping method, which can improve blade performance at a relatively low cost. Summary of the invention

[0006] The purpose of the present invention is to provide a two-dimensional blade shaping method, which can improve the performance of the blade at a relatively low cost.

[0007] The present invention provides a two-dimensional blade profile shaping method, comprising:

[0008] Step S11: obtaining an initial blade profile thickness distribution curve, wherein an initial suction surface thickness distribution curve and an initial pressure surface thickness distribution curve are located at an upper side and a lower side, respectively;

[0009] Step S12: determining a point P1, where P1 is located a predetermined distance below an initial leading edge point of an initial blade profile thickness distribution curve;

[0010] Step S13: constructing a new suction surface thickness distribution curve, including:

[0011] Determine a point P4, P4 is on the initial suction surface thickness distribution curve, and determine the portion of the initial suction surface thickness distribution curve located on the right side of P4 as the initial blade suction surface thickness distribution curve;

[0012] With P1 and P4 as the starting point and end point, a third-order Bezier curve is constructed, which is connected with the initial blade suction surface thickness distribution curve to form a new suction surface thickness distribution curve, so that the first-order derivative and the second-order derivative of the new suction surface thickness distribution curve are continuous at P4 and the tangent vector is vertical at P1;

[0013] Step S14: constructing a new pressure surface thickness distribution curve, including:

[0014] Determine point P4', P4' is on the initial pressure surface thickness distribution curve, and determine the portion of the initial pressure surface thickness distribution curve located on the right side of P4' as the initial blade pressure surface thickness distribution curve;

[0015] With P1 and P4' as the starting point and end point, a third-order Bezier curve is constructed, which is connected with the initial blade pressure surface thickness distribution curve to form a new pressure surface thickness distribution curve, so that the first-order derivative and the second-order derivative of the new pressure surface thickness distribution curve are continuous at P4 and the tangent vector is vertical at P1;

[0016] Step S15: The new suction surface thickness distribution curve and the new pressure surface thickness distribution curve constitute a new blade thickness distribution curve;

[0017] Step S16: superimpose the new blade thickness distribution curve onto the mid-camber line to obtain a new two-dimensional blade profile.

[0018] In one embodiment, in step S13, constructing a new suction surface thickness distribution curve further includes:

[0019] Determine a point P2, wherein P2 is located a predetermined distance above P1;

[0020] By ensuring the continuity of the first-order derivative and the second-order derivative at P4, point P3 is obtained;

[0021] Generate a third-order Bezier curve with P1 and P4 as the starting point and end point and P2 and P3 as the control points; and

[0022] In step S14, constructing a new pressure surface thickness distribution curve further includes:

[0023] Determine a point P2', wherein P2' is located a predetermined distance below P1;

[0024] By ensuring the continuity of the first-order derivative and the second-order derivative at P4', point P3' is obtained;

[0025] A third-order Bezier curve is generated with P1 and P4' as the start and end points and P2' and P3' as control points.

[0026] In one embodiment, in step S11, the initial blade profile thickness distribution curve is placed in an XY coordinate system, wherein the initial suction surface thickness distribution curve and the initial pressure surface thickness distribution curve are located in the first quadrant and the fourth quadrant respectively, and the initial leading edge point is located at the origin of the coordinate system; and

[0027] In step S12, P1 is located at the negative half axis of the Y axis.

[0028] In one embodiment, in step S13, constructing a new suction surface thickness distribution curve further includes:

[0029] Determine point P2, where P2 is on the Y axis and above P1;

[0030] By ensuring the continuity of the first-order derivative and the second-order derivative at P4, point P3 is obtained;

[0031] Generate a third-order Bezier curve with P1 and P4 as the starting point and end point and P2 and P3 as the control points; and

[0032] In step S14, constructing a new pressure surface thickness distribution curve further includes:

[0033] Determine point P2', where P2' is on the Y axis and below P1';

[0034] By ensuring the continuity of the first-order derivative and the second-order derivative at P4', point P3' is obtained;

[0035] A third-order Bezier curve is generated with P1 and P4' as the start and end points and P2' and P3' as control points.

[0036] In one embodiment, the two-dimensional blade profiling method further comprises: determining parameters k0, k1, k2, k1' and k2';

[0037] In step S11, the initial blade profile thickness distribution curve has a leading edge radius r0;

[0038] In step S12, when point P1 is determined, the ordinate Y1 of P1 is -k0*r0;

[0039] In step S13, when point P4 is determined, the horizontal coordinate X4 of P4 is equal to k1*r0, and when point P2 is determined, the vertical coordinate Y2 of P2 is equal to k2*(Y4-Y1)+Y1, where Y4 is the vertical coordinate of P4;

[0040] In step S14, when determining point P4', the abscissa X4' of P4'=k1'*r0, and when determining point P2', the ordinate Y2' of P2'=k2'*(Y4'-Y1)+Y1, wherein Y4' is the ordinate of P4'.

[0041] The present invention also provides a blade optimization method, comprising:

[0042] Step S01: taking a set of parameters k0, k1, k2, k1' and k2' as a sample, obtaining multiple samples and generating an initial sample library;

[0043] Step S02: constructing a two-dimensional leaf profile using the two-dimensional leaf profile modeling method based on the initial sample library;

[0044] Step S03: for the two-dimensional blade profile, blade modeling and numerical solution are carried out, and the calculation results are extracted as response values;

[0045] Step S04: constructing a proxy model based on the initial sample library and the response value;

[0046] Step S05: Optimize the constructed proxy model to find the optimal solution of the calculation model;

[0047] Step S06: for the optimal solution, the two-dimensional blade profile modeling method is used to construct a two-dimensional blade profile, and blade modeling and numerical solution are carried out;

[0048] Step S07: Compare the response value obtained in step S06 with the response value corresponding to the optimal solution in step S05. If the deviation between the two is less than a predetermined value, it is determined that the convergence requirement is met, and the optimal solution is taken as the optimization result, and the process ends; otherwise, it is determined that no convergence has been achieved, and the optimal solution is taken as a new sample, added to the initial sample library, and steps S4 to S7 are repeated.

[0049] In one embodiment, an upper limit is set, and if the number of times step S07 is performed exceeds the upper limit and convergence has not yet occurred, the optimal solution corresponding to the existing sample library is obtained as the optimization result, and the process ends.

[0050] The present invention further provides a two-dimensional blade profile, characterized in that it is constructed by the above-mentioned two-dimensional blade profile modeling method.

[0051] Using the above two-dimensional blade modeling method, during the two-dimensional blade design process, the profile of the blade near the leading edge area can be locally optimized without adjusting the entire blade body blade profile, and the connection between the optimized area and the blade body is second-order continuous, which can improve the leading edge flow field distribution, adapt to the inlet flow under different attack angles, and increase the low-loss attack angle range. In general, when using the above two-dimensional blade modeling method to construct the blade profile, only the near-leading edge area is reshaped, which can achieve a refined leading edge design without changing the blade body geometry, and can achieve improved blade performance at a relatively low cost.

[0052] When the above-mentioned two-dimensional blade modeling method is used to construct the blade shape, the small-scale reconstruction of the leading edge will cause little change to the entire three-dimensional blade. Generally, no new strength stress risks will be generated, and there is no need to redesign the structure such as the tenon edge plate. Only the blade area needs to be replaced, which can reduce the optimization workload of the structure and strength engineers and improve the economy of the optimization work.

[0053] Furthermore, the above two-dimensional blade profiling method adopts five dimensionless parameters k0, k1, k2, k1' and k2', which makes the adjustment more flexible and realizes parameterization of design variables, which is beneficial to blade optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0055] Figure 1 It is a schematic diagram of a two-dimensional leaf profile.

[0056] Figure 2 It is a schematic diagram of the initial blade thickness distribution curve.

[0057] Figure 3 This is a partial enlarged view of the leading edge area of ​​the new blade thickness distribution curve.

[0058] Figure 4 This is a comparison chart of the effects before and after the leading edge adjustment.

[0059] Figure 5 yes Figure 4 A partial enlarged view of area A in the middle.

[0060] Figure 6 These are exemplary steps of the two-dimensional airfoil modeling method according to the present invention.

[0061] Figure 7 These are exemplary steps of a preferred embodiment of the two-dimensional airfoil modeling method according to the present invention.

[0062] Figure 8 It is a schematic diagram comparing the Mach number on the blade surface before and after adjustment.

[0063] Fig. 9 It is a comparative diagram of the low-loss angle of attack range of the blade before and after adjustment.

[0064] Fig.10 are exemplary steps of the blade optimization method according to the present invention.

[0065] Fig.11 These are exemplary steps of a preferred embodiment of the blade optimization method according to the present invention. DETAILED DESCRIPTION

[0066] The present invention is further described below in conjunction with specific implementation methods and accompanying drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from this description. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific implementation method.

[0067] For example, a first feature described later in the specification as being formed above or on a second feature may include an embodiment in which the first feature and the second feature are formed by direct connection, and may also include an embodiment in which an additional feature is formed between the first feature and the second feature, so that the first feature and the second feature may not be directly connected. Further, when a first element is described as being connected or combined with a second element, the description includes an embodiment in which the first element and the second element are directly connected or combined with each other, and also includes an embodiment in which one or more other intervening elements are added to indirectly connect or combine the first element and the second element.

[0068] See also Figure 1 , Figure 1 Schematic diagram of a two-dimensional blade profile 10. The two-dimensional blade profile 10 has a leading edge 11 and a trailing edge 12. The outer surface of the two-dimensional blade profile 10 is composed of a suction surface 13 and a pressure surface 14. In the current conventional design method of a two-dimensional blade profile, a two-dimensional blade profile is generated by superimposing a blade profile thickness distribution curve 30 (superimposed thickness t0) along a normal direction on a camber line 20.

[0069] Conventional blade thickness distribution curve 30 is as follows Figure 2As shown, the thickness of the suction surface and the pressure surface are symmetrically distributed along the chord length CL, that is, the suction surface thickness distribution curve 33 and the pressure surface thickness distribution curve 34 are symmetrically distributed along the chord length CL. The leading edge thickness distribution curve 31 is a circular arc or an elliptical arc. The point located at the frontmost side (the leftmost side) in the leading edge thickness distribution curve 31 is the leading edge point P0. The portion of the leading edge thickness distribution curve 31 located on the upper side of the chord length CL constitutes a portion of the suction surface thickness distribution curve 33, and the portion of the leading edge thickness distribution curve 31 located on the lower side of the chord length CL constitutes a portion of the pressure surface thickness distribution curve 34. It should be understood that Figure 2 The leading edge thickness distribution curve 31 enclosed by a dotted line is only exemplary, and it is not required that the upper part of the leading edge thickness distribution curve 31 constituting the suction surface thickness distribution curve 33 and the lower part constituting the pressure surface thickness distribution curve 34 are completely symmetrical. Figure 2 P4 and P4', which are the connection points between the suction front edge, the pressure front edge and the blade body respectively, are not necessarily symmetrical with respect to the chord length CL. Figure 2 Also shown is a trailing edge thickness distribution curve 32 , which is also referred to herein as a part of the blade airfoil thickness distribution curve.

[0070] The blade thickness distribution curve 30 may have a leading edge radius r0, which is also the radius of the leading edge thickness distribution curve 31. When the leading edge thickness distribution curve 31 is a circular arc, the leading edge radius r0 is also the radius of the circular arc; and when the leading edge thickness distribution curve 31 is an elliptical arc, the leading edge radius r0 may be the short radius of the elliptical arc, the long radius of the elliptical arc, or the average of the short radius and the long radius of the elliptical arc.

[0071] Figure 2 The blade thickness distribution curve 30 can be used as the initial blade thickness distribution curve to be described below, and is hereinafter referred to as the initial blade thickness distribution curve 30. Similarly, the leading edge point P0 can be referred to as the initial leading edge point P0; the suction surface thickness distribution curve 33 can be referred to as the initial suction surface thickness distribution curve 33; the pressure surface thickness distribution curve 34 can be referred to as the initial pressure surface thickness distribution curve 34; and so on.

[0072] The present invention provides a two-dimensional blade modeling method. A two-dimensional blade can be constructed by the two-dimensional blade modeling method. Figures 3 to 6 The two-dimensional blade shaping method of the present invention is described. Figure 6 shows an overview flow chart of the two-dimensional blade profiling method, Figure 3 shows an example method for creating a blade thickness distribution curve, Figure 4 and Figure 5An example configuration of a two-dimensional blade profile is shown. The term "comprising" in the text only indicates that the steps and elements that have been clearly identified are included, and these steps and elements do not constitute an exclusive list, and the method or device may also include other steps or elements. Moreover, the order in which the steps are listed in the text does not represent the order that must be followed in actual execution.

[0073] Step S11: Obtain the initial blade thickness distribution curve, for example, Figure 2 The blade thickness distribution curve 30 is shown in FIG.

[0074] In the initial blade profile thickness distribution curve 30 obtained in step S11 , the initial suction surface thickness distribution curve 33 and the initial pressure surface thickness distribution curve 34 are located at the upper side and the lower side, respectively.

[0075] Step S12 : determining a point P1 , where P1 is located a predetermined distance δ below the initial leading edge point P0 of the initial airfoil thickness distribution curve 30 .

[0076] In step S12, P1 can be obtained by moving P0 downward by a predetermined distance δ.

[0077] Step S13: construct a new suction surface thickness distribution curve 33a.

[0078] Step S13 may include:

[0079] Step S131: determining a point P4, where P4 is on the initial suction surface thickness distribution curve 33, and determining a portion of the initial suction surface thickness distribution curve 33 located on the right side of P4 as an initial blade suction surface thickness distribution curve 331;

[0080] Step S132: With P1 and P4 as the starting point and the end point, a third-order Bezier curve 332a is constructed, and connected with the initial blade suction surface thickness distribution curve 331 to form a new suction surface thickness distribution curve 33a, so that the first-order derivative and the second-order derivative of the new suction surface thickness distribution curve 33a are continuous at P4 and the tangent vector is vertical at P1.

[0081] Step S14: construct a new pressure surface thickness distribution curve 34a.

[0082] Step S14 may include:

[0083] Step S141: determining a point P4′, where P4′ is on the initial pressure surface thickness distribution curve 34, and determining a portion of the initial pressure surface thickness distribution curve 34 located to the right of P4′ as the initial blade airfoil pressure surface thickness distribution curve 341;

[0084] Step S142: With P1 and P4 as the starting point and the end point, a third-order Bezier curve 342a is constructed, and connected with the initial blade pressure surface thickness distribution curve 341 to form a new pressure surface thickness distribution curve 34a, so that the first-order derivative and the second-order derivative of the new pressure surface thickness distribution curve 34a are continuous at P4 and the tangent vector is vertical at P1.

[0085] Step S15: The new suction surface thickness distribution curve 33a and the new pressure surface thickness distribution curve 34a constitute a new blade profile thickness distribution curve 30a.

[0086] Step S16: superimpose the new blade thickness distribution curve 30a onto the mid-camber line, for example Figure 1 By adjusting the mid-camber line 20 in the blade, a new two-dimensional blade profile 40a is obtained.

[0087] Figure 5 In FIG. 1 , the mean camber line 20 is shown by a dashed line, the initial two-dimensional blade profile 40 (prototype blade profile) is shown by a dotted line, and the new two-dimensional blade profile 40a (new blade profile) is shown by a solid line.

[0088] Figure 3 In the illustrated embodiment, in step S13, constructing a new suction surface thickness distribution curve 33a may further include:

[0089] A point P2 is determined, wherein P2 is located a predetermined distance above P1.

[0090] By ensuring the continuity of the first-order derivative and the second-order derivative at P4, point P3 is obtained.

[0091] With P1 and P4 as the start and end points and P2 and P3 as control points, a third-order Bezier curve 332 a is generated.

[0092] Similarly, in step S14, constructing a new pressure surface thickness distribution curve 34a may also include:

[0093] Determine a point P2', wherein P2' is located a predetermined distance below P1;

[0094] By ensuring the continuity of the first-order derivative and the second-order derivative at P4', point P3' is obtained;

[0095] With P1 and P4' as the start and end points and P2' and P3' as control points, a third-order Bezier curve 342a is generated.

[0096] Figure 3In the illustrated embodiment, in step S11, the initial blade profile thickness distribution curve 30 may be placed in an XY coordinate system, wherein the initial suction surface thickness distribution curve 33 and the initial pressure surface thickness distribution curve 34 are located in the first quadrant and the fourth quadrant, respectively, and the initial leading edge point P0 is located at the coordinate origin O. Accordingly, in step S12, P1 is located at the negative half axis of the Y axis.

[0097] Furthermore, in step S13, constructing a new suction surface thickness distribution curve 33a may further include:

[0098] Determine point P2, where P2 is on the Y axis and above P1;

[0099] By ensuring the continuity of the first-order derivative and the second-order derivative at P4, point P3 is obtained;

[0100] With P1 and P4 as the start and end points and P2 and P3 as control points, a third-order Bezier curve 332 a is generated.

[0101] Similarly, in step S14, constructing a new pressure surface thickness distribution curve 34a may also include:

[0102] Determine point P2', where P2' is on the Y axis and below P1';

[0103] By ensuring the continuity of the first-order derivative and the second-order derivative at P4', point P3' is obtained;

[0104] With P1 and P4' as the start and end points and P2' and P3' as control points, a third-order Bezier curve 342a is generated.

[0105] Furthermore, preferably, the two-dimensional blade profiling method according to the present invention may further include: determining parameters k0, k1, k2, k1' and k2';

[0106] In step S11, the initial blade profile thickness distribution curve has a leading edge radius r0;

[0107] In step S12, when point P1 is determined, the ordinate Y1 of P1 is -k0*r0;

[0108] In step S13, when point P4 is determined, the horizontal coordinate X4 of P4 is equal to k1*r0, and when point P2 is determined, the vertical coordinate Y2 of P2 is equal to k2*(Y4-Y1)+Y1, where Y4 is the vertical coordinate of P4;

[0109] In step S14, when determining point P4', the abscissa X4' of P4 is equal to k1'*r0, and when determining point P2', the ordinate Y2' of P2' is equal to k2'*(Y4'-Y1)+Y1, wherein Y4' is the ordinate of P4'.

[0110] According to the above preferred embodiments of the two-dimensional blade shaping method of the present invention, Figure 7 As shown, it may include steps S100 to S160 which will be described below. In this text, Xm represents the abscissa of point Pm, Ym represents the ordinate of point Pm, and M0<X0,Y0> Represents point M0 with abscissa X0 and ordinate Y0.

[0111] Step S100: Determine parameters k0, k1, k2, k1' and k2'.

[0112] Step S110: obtaining an initial blade profile thickness distribution curve 30 having a leading edge radius r0, and placing the initial blade profile thickness distribution curve 30 in an XY coordinate system.

[0113] The initial leading edge point P0 is located at the coordinate origin O<0, 0>, the initial suction surface thickness distribution curve 33 is located in the first quadrant, and the initial pressure surface thickness distribution curve 34 is located in the fourth quadrant.

[0114] Step S120: Determine point P1<X1,Y1> , where X1=0 and Y1=-k0*r0.

[0115] In step S120, P1, ie, the adjusted leading edge point obtained by moving the initial leading edge point P0 along the negative direction of the Y axis by a distance δ, where the value of δ can be determined by multiplying the leading edge radius r0 by a proportionality coefficient k0.

[0116] Step S130: constructing a new suction surface thickness distribution curve 33a, including:

[0117] Step S1301: Determine point P4<X4,Y4> , P4 is a point on the initial suction surface thickness distribution curve 33 , and X4=k1*r0, and the portion of the initial suction surface thickness distribution curve 33 located on the right side of P4 is determined as the initial blade suction surface thickness distribution curve 331 .

[0118] In step S1301, the horizontal coordinate X4 of P4 can be determined by multiplying the leading edge radius r0 by a proportional coefficient k1, thereby determining the adjustment range of the front edge area of ​​the suction surface. P4 divides the initial suction surface thickness distribution curve 33 into an initial leading edge suction surface thickness distribution curve 332 located on the left and an initial blade suction surface thickness distribution curve 331 located on the right, as shown in FIG. Figure 2 shown.

[0119] Step S1302: Determine point P2<X2,Y2> , where X2=0 and Y2=k2*(Y4-Y1)+Y1.

[0120] In step S1302 , the vertical coordinate Y2 of P2 may be determined by a proportionality coefficient k2 between the vertical coordinate Y1 of P1 and the vertical coordinate Y4 of P4 .

[0121] Step S1303: Obtain point P3 by ensuring the continuity of the first-order derivative and the second-order derivative at P4.

[0122] For example, the first-order derivative Y'4 and the second-order derivative Y"4 at P4 can be calculated based on the initial suction surface thickness distribution curve 33. Then, based on the first-order derivative Y'4 and the second-order derivative Y"4, the newly generated curve is ensured to be continuous with the first-order derivative and the second-order derivative of the initial blade suction surface thickness distribution curve 331 at P4, and the horizontal coordinate X3 and the vertical coordinate Y3 of P3 can be calculated. Specifically, the horizontal coordinate X3 and the vertical coordinate Y3 of P3 can be obtained by jointly solving the following two equations.

[0123] Y'4=(Y2+Y4-2*Y3) / (X2+X4-2X3);

[0124] Y'4 = (Y4 - Y3) / (X4 - X3).

[0125] Step S1304: With P1 and P4 as the starting point and the end point and P2 and P3 as the control points, a third-order Bezier curve 332a is generated, and connected with the initial blade suction surface thickness distribution curve 331 to form a new suction surface thickness distribution curve 34a.

[0126] In step S1304 , the third-order Bezier curve 332 a with P1 and P4 as the starting point and the end point, ie, the new suction surface front edge thickness distribution curve, can replace the initial suction surface front edge thickness distribution curve 332 .

[0127] Step S140: construct a new pressure surface thickness distribution curve 34a. Referring to step S130, step S140 may similarly use coefficients or parameters k1' and k2' to determine four characteristic points P1', P2', P3', and P4' of the pressure surface, and construct a third-order Bezier curve, wherein characteristic point P1' coincides with point P1, that is, point P1. Step S140 may include:

[0128] Step S1401: Determine point P4'<X4’,Y4’> , P4′ is a point on the initial pressure surface thickness distribution curve, and X4′=k1′*r0, and the portion of the initial pressure surface thickness distribution curve 34 located on the right side of P4′ is determined as the initial blade pressure surface thickness distribution curve 341 .

[0129] In step S1401, the horizontal coordinate X4' of P4' can be determined by multiplying the leading edge radius r0 by a proportionality coefficient k1', thereby determining the adjustment range of the front edge area of ​​the pressure surface. P4' divides the initial pressure surface thickness distribution curve 34 into an initial leading edge pressure surface thickness distribution curve 342 located on the left and an initial blade pressure surface thickness distribution curve 341 located on the right, as shown in FIG. Figure 2 shown.

[0130] Step S1402: Determine point P2'<X2’,Y2’> , where X2'=0 and Y2'=k2'*(Y4'-Y1)+Y1.

[0131] In step S1402 , the ordinate Y2 ′ of P2 ′ may be determined by a proportionality coefficient k2 ′ between the ordinate Y1 of P1 and the ordinate Y4 ′ of P4 ′.

[0132] Step S1403: Obtain point P3' by ensuring the continuity of the first-order derivative and the second-order derivative at P4'.

[0133] For example, the first-order derivative Y'4' and the second-order derivative Y"4' at P4' can be calculated based on the initial pressure surface thickness distribution curve 34. Then, based on the first-order derivative Y'4' and the second-order derivative Y"4', the newly generated curve is ensured to be continuous with the first-order derivative and the second-order derivative of the initial blade pressure surface thickness distribution curve 341 at P4', and the abscissa X3' and the ordinate Y3' of P3' can be calculated. Specifically, the abscissa X3' and the ordinate Y3' of P3' can be obtained by jointly solving the following two equations.

[0134] Y"4'=(Y2'+Y4'-2*Y3') / (X2'+X4'-2X3');

[0135] Y'4'=(Y4'-Y3') / (X4'-X3').

[0136] Step S1404: Generate a third-order Bezier curve 342a with P1 and P4' as the starting point and end point and P2' and P3' as the control points, and connect it with the initial blade pressure surface thickness distribution curve 341 to form a new pressure surface thickness distribution curve 34a.

[0137] In step S1404 , the third-order Bezier curve 342 a with P1 and P4 ′ as the starting point and the end point, ie, the new pressure surface front edge thickness distribution curve, may replace the initial pressure surface front edge thickness distribution curve 342 .

[0138] Step S150: The new suction surface thickness distribution curve 33a and the new pressure surface thickness distribution curve 34a constitute a new blade profile thickness distribution curve 30a.

[0139] Step S160: superimpose the new blade profile thickness distribution curve 30a onto the mid-camber line 20 to obtain a new two-dimensional blade profile 40a.

[0140] The two-dimensional blade shaping method according to the present invention is based on the curve of thickness distribution along the chord length direction, by adjusting the thickness distribution of the suction surface and pressure surface near the leading edge area respectively, and adjusting the radial position of the leading edge point at the same time, and locally adjusting the leading edge thickness distribution shape. Figure 4 and Figure 5 It can be seen that the local adjustment of the leading edge has a very small impact on the entire blade profile area, and the newly generated blade profile can ensure the second-order continuity of the connection position between the adjustment area and the prototype blade, and the leading edge stagnation point position ensures first-order continuity.

[0141] As mentioned above, the order in which the steps are listed in the text does not represent the order that must be followed in actual execution. For example, although determining parameters k0, k1, k2, k1' and k2' is listed first as step S100, parameter k0 can be determined immediately before determining point P1 in step S120, or parameter k2 can be determined immediately before determining point P2 in step S1302.

[0142] Figure 8 and Fig. 9 A comparison chart of the calculation results of the new two-dimensional blade profile scheme constructed according to the two-dimensional blade profile modeling method of the present invention and the prototype blade profile is given, where: Figure 8 This is a comparison diagram of the Mach number on the blade surface before and after adjustment. Fig. 9 This is a comparison diagram of the low-loss angle of attack range of the front and rear blades after adjustment. Fig. 9 The low-loss angle of attack range of the prototype and the new blade scheme under two inlet Mach number conditions is shown. Figure 8 It can be seen that the new blade profile can eliminate the leading edge spike and effectively improve the Mach number distribution shape of the blade surface near the leading edge. Fig. 9 It can be seen that the new blade profile does not change much in the negative angle of attack region; in the positive angle of attack range, the low-loss angle of attack range can be increased by about 2°-3° compared with the prototype scheme, and the margin improvement effect is obvious, indicating that the blade profile optimized by the new method can operate in a wider angle of attack range.

[0143] Fig.10 The general steps of the blade optimization method provided by the present invention are shown. Fig.11 The following are the general steps of the blade optimization method provided by the present invention.

[0144] See also Fig.10 and Fig.11 The blade optimization method provided by the present invention includes the following steps.

[0145] Step S01: Taking a set of parameters k0, k1, k2, k1' and k2' as a sample, multiple samples are obtained to generate an initial sample library.

[0146] The geometric model of the two-dimensional blade profile to be optimized can be determined, and an initial sample database can be generated using a design of experiments (DOE) method based on leading edge refined design parameters k0, k1, k2, k1' and k2'.

[0147] Step S02: Based on the initial sample library, a two-dimensional blade profile is constructed by using the two-dimensional blade profile modeling method previously modeled by using parameters k0, k1, k2, k1' and k2'.

[0148] A two-dimensional blade profile is constructed based on the input parameters of each sample in the initial sample library. In other words, based on the design parameters k0, k1, k2, k1' and k2', a local area of ​​the leading edge is modeled to construct a new two-dimensional blade profile.

[0149] Step S03: for the two-dimensional blade shape, blade modeling and numerical solution are carried out, and the calculation results are extracted as response values.

[0150] For each two-dimensional blade shape constructed according to the input parameters of each sample in the initial sample library, blade modeling and numerical solution are carried out, and the calculation results are extracted as the response value of each sample.

[0151] Blade modeling and numerical solution work, for example, see Fig.11 , which can be broken down into:

[0152] Using the two-dimensional blade profile constructed in step S2 as a geometric model, and based on the geometric model, generating a two-dimensional S1 flow surface calculation grid;

[0153] Using the MISES solver, the flow field on the S1 surface is calculated, and the low-loss angle of attack characteristics are calculated;

[0154] The calculation results such as blade profile loss value and low loss angle of attack range are extracted as the response value of the sample.

[0155] Step S04: construct a proxy model based on the initial sample library and response values.

[0156] The proxy model may be, for example, a polynomial model, a Kriging model, a RBF model, a CNN model, and the like.

[0157] Step S05: Optimize the constructed proxy model to find the optimal solution of the calculation model.

[0158] The optimization algorithm may be, for example, a genetic algorithm, a particle swarm algorithm, an ant colony algorithm, or the like.

[0159] Step S06: For the optimal solution, a two-dimensional blade shape modeling method using the parameters k0, k1, k2, k1' and k2' is used to construct a two-dimensional blade shape, and blade modeling and numerical solution are performed.

[0160] The optimal solution calculated based on the proxy model is modeled and numerically solved for the blades.

[0161] Step S07: Compare the response value obtained in step S06 with the response value corresponding to the optimal solution in step S05. If the deviation between the two is less than a predetermined value, it is determined that the convergence requirement is met, and the optimal solution is taken as the optimization result, and the process ends; otherwise, it is determined that no convergence has been achieved, and the optimal solution is taken as a new sample, added to the initial sample library, and steps S04 to S07 are repeated.

[0162] The solution calculated numerically in step S06 is compared with the optimal solution of the model. If the deviation between the two is less than a certain limit value, it is considered that the accuracy of the proxy model is high enough, and the convergence judgment is that the convergence requirements are met and the optimal solution is obtained; if the requirements are not met, the optimal solution of the model is taken as a new sample and added to the initial sample library, that is, the sample library is rebuilt, and steps S04 to S07 are re-executed until convergence.

[0163] In one embodiment, an upper limit value may be set. If the number of times step S07 is executed exceeds the upper limit value and still fails to converge, the optimal solution corresponding to the existing sample library is obtained as the optimization result, and the process ends. In other words, an upper limit value of the number of iteration steps may be set according to actual conditions. If the number of times step S07 is executed exceeds the upper limit value and still fails to converge, the optimal solution in the existing sample library result may be taken as the optimal solution.

[0164] The above blade optimization method models the local area of ​​the leading edge by using a two-dimensional blade modeling method with design variables, thereby constructing a two-dimensional blade shape. The optimization process can be dimensionless, and the optimization work is mainly concentrated in the area near the leading edge, which greatly reduces the workload.

[0165] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. For example, the transformation modes under different implementation modes may be appropriately combined. Therefore, any modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A two-dimensional blade modeling method, characterized in that: include: Step S11: obtaining an initial blade profile thickness distribution curve, wherein an initial suction surface thickness distribution curve and an initial pressure surface thickness distribution curve are located at an upper side and a lower side, respectively; Step S12: determining a point P1, where P1 is located a predetermined distance below an initial leading edge point of an initial blade profile thickness distribution curve; Step S13: constructing a new suction surface thickness distribution curve, including: Determine a point P4, P4 is on the initial suction surface thickness distribution curve, and determine the portion of the initial suction surface thickness distribution curve located on the right side of P4 as the initial blade suction surface thickness distribution curve; With P1 and P4 as the starting point and end point, a third-order Bezier curve is constructed, which is connected with the initial blade suction surface thickness distribution curve to form a new suction surface thickness distribution curve, so that the first-order derivative and the second-order derivative of the new suction surface thickness distribution curve are continuous at P4 and the tangent vector is vertical at P1; Step S14: constructing a new pressure surface thickness distribution curve, including: Determine point P4', P4' is on the initial pressure surface thickness distribution curve, and determine the portion of the initial pressure surface thickness distribution curve located on the right side of P4' as the initial blade pressure surface thickness distribution curve; With P1 and P4' as the starting point and end point, a third-order Bezier curve is constructed, which is connected with the initial blade pressure surface thickness distribution curve to form a new pressure surface thickness distribution curve, so that the first-order derivative and the second-order derivative of the new pressure surface thickness distribution curve are continuous at P4 and the tangent vector is vertical at P1; Step S15: The new suction surface thickness distribution curve and the new pressure surface thickness distribution curve constitute a new blade thickness distribution curve; Step S16: superimpose the new blade thickness distribution curve onto the mid-camber line to obtain a new two-dimensional blade profile.

2. The two-dimensional blade shaping method according to claim 1, characterized in that: In step S13, constructing a new suction surface thickness distribution curve further includes: Determine a point P2, wherein P2 is located a predetermined distance above P1; By ensuring the continuity of the first-order derivative and the second-order derivative at P4, point P3 is obtained; Generate a third-order Bezier curve with P1 and P4 as the starting point and end point and P2 and P3 as the control points; and In step S14, constructing a new pressure surface thickness distribution curve further includes: Determine a point P2', wherein P2' is located a predetermined distance below P1; By ensuring the continuity of the first-order derivative and the second-order derivative at P4', point P3' is obtained; A third-order Bezier curve is generated with P1 and P4' as the start and end points and P2' and P3' as control points.

3. The two-dimensional blade shaping method according to claim 1, characterized in that: In step S11, the initial blade thickness distribution curve is placed in an XY coordinate system, wherein the initial suction surface thickness distribution curve and the initial pressure surface thickness distribution curve are located in the first quadrant and the fourth quadrant respectively, and the initial leading edge point is located at the origin of the coordinate system; and In step S12, P1 is located at the negative half axis of the Y axis.

4. The two-dimensional blade shaping method according to claim 3, characterized in that: In step S13, constructing a new suction surface thickness distribution curve further includes: Determine point P2, where P2 is on the Y axis and above P1; By ensuring the continuity of the first-order derivative and the second-order derivative at P4, point P3 is obtained; Generate a third-order Bezier curve with P1 and P4 as the starting point and end point and P2 and P3 as the control points; and In step S14, constructing a new pressure surface thickness distribution curve further includes: Determine point P2', where P2' is on the Y axis and below P1'; By ensuring the continuity of the first-order derivative and the second-order derivative at P4', point P3' is obtained; A third-order Bezier curve is generated with P1 and P4' as the start and end points and P2' and P3' as control points.

5. The two-dimensional blade shaping method according to claim 4, characterized in that: The two-dimensional blade profiling method further includes: determining parameters k0, k1, k2, k1' and k2'; In step S11, the initial blade profile thickness distribution curve has a leading edge radius r0; In step S12, when point P1 is determined, the ordinate Y1 of P1 is -k0*r0; In step S13, when point P4 is determined, the horizontal coordinate X4 of P4 is equal to k1*r0, and when point P2 is determined, the vertical coordinate Y2 of P2 is equal to k2*(Y4-Y1)+Y1, where Y4 is the vertical coordinate of P4; In step S14, when determining point P4', the abscissa X4' of P4'=k1'*r0, and when determining point P2', the ordinate Y2' of P2'=k2'*(Y4'-Y1)+Y1, wherein Y4' is the ordinate of P4'.

6. A blade optimization method, characterized in that: include: Step S01: taking a set of parameters k0, k1, k2, k1' and k2' as a sample, obtaining multiple samples and generating an initial sample library; Step S02: constructing a two-dimensional leaf profile based on the initial sample library using the two-dimensional leaf profile modeling method as claimed in claim 5; Step S03: for the two-dimensional blade profile, blade modeling and numerical solution are carried out, and the calculation results are extracted as response values; Step S04: constructing a proxy model based on the initial sample library and the response value; Step S05: Optimize the constructed proxy model to find the optimal solution of the calculation model; Step S06: for the optimal solution, a two-dimensional blade profile is constructed using the two-dimensional blade profile modeling method as claimed in claim 5, and blade modeling and numerical solution are carried out; Step S07: Compare the response value obtained in step S06 with the response value corresponding to the optimal solution in step S05. If the deviation between the two is less than a predetermined value, it is determined that the convergence requirement is met, and the optimal solution is taken as the optimization result, and the process ends; otherwise, it is determined that no convergence has been achieved, and the optimal solution is taken as a new sample, added to the initial sample library, and steps S4 to S7 are repeated.

7. The blade optimization method according to claim 6, characterized in that: An upper limit value is set, and if the number of times step S07 is executed exceeds the upper limit value and convergence has not yet occurred, the optimal solution corresponding to the existing sample library is obtained as the optimization result, and the process ends.

8. A two-dimensional blade profile, characterized in that: It is constructed by the two-dimensional blade profile modeling method according to any one of claims 1 to 5.

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