A blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor

Abstract

The present invention discloses a blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor. By numerically simulating a high-load compressor blade grid, the transport characteristics of the blade tip leakage flow in the channel are analyzed, and the intersection position of the double leakage trajectory with the adjacent blade pressure surface is determined. With this as the center, a sinusoidal two-dimensional bulge is generated at different flow direction positions, which is then projected onto the pressure surface along the local normal. The starting / ending positions and peak values ​​of the two-dimensional bulges at different spanwise positions are adjusted, and stacked along the spanwise direction to obtain a blade tip three-dimensional geometric structure with the pressure surface belly bulge as the main feature. The blade shaping method of the present invention enhances the axial momentum of the blade tip through pressure field reconstruction, weakens the strength of the blade tip double leakage, and delays the upstream movement of the leakage flow-mainstream interface. While effectively widening the stable operating margin, it can also ensure the aerodynamic efficiency of the blade tip, and does not increase the complexity of the blade tip structure. It can be directly applied to the refined design of high-load compressor blade tips.

Description

Technical Field

[0001] The present invention belongs to the technical field of aero-engine compressor component design, and relates to high-load compressor blade design and flow control, and specifically to a blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor by means of a local three-dimensional convex structure on the pressure surface. Background Art

[0002] To further improve thrust-to-weight ratios, high-load compressors have become a key development trend in future advanced aeroengine design. High-load compressors play a critical role in aeroengines, and their performance directly impacts the engine's overall efficiency and stability. However, as compressor load increases, the flow and circumferential pressure gradients within the duct increase, easily inducing large-scale separation. Furthermore, tip leakage flow can further exacerbate local turbulent mixing and aerodynamic blockage. When the tip clearance increases or the load level continues to rise, the compressor tip leakage flow, after escaping the suction surface, can cross the entire blade pitch in the duct and enter the adjacent blade tip clearance, resulting in a so-called double leakage phenomenon. Double leakage induces vortex chains through vortex-vortex interference, invading the leakage core area near the suction surface of adjacent blades, ultimately inducing vortex breakup and negatively impacting compressor efficiency and stability margins. Therefore, controlling tip double leakage is crucial to ensuring efficient and stable operation of high-load compressors.

[0003] When double leakage occurs at the blade tip, the vortex-vortex interference and the fragmentation of the large-scale vortex structure lead to a rapid expansion of the low axial momentum area, and the strong blockage induced by this is the key factor triggering the instability of the blade tip. Therefore, how to enhance the axial momentum of the blade tip and the corresponding flow capacity is the fundamental goal of the blade tip double leakage control. Common methods in the existing technology such as casing treatment and blade tip injection enhance the momentum exchange between the jet and the low-energy fluid at the blade tip by introducing the jet effect, thereby weakening or even eliminating the low momentum area at the blade tip. However, there are also some inherent defects in the application of control methods such as casing treatment and blade tip injection. First, these methods usually require the addition of additional structures in the blade tip area, resulting in more complex blade tip geometry and increasing the difficulty of design and manufacturing. Secondly, these methods will usually inevitably induce strong turbulent mixing and aerodynamic losses, that is, there is a problem that it is difficult to balance efficiency and stability margin.

[0004] As mentioned above, as compressor design develops towards high load and high efficiency, the impact of double leakage at the blade tip on compressor efficiency and stability has become increasingly prominent. Although the existing methods of enhancing the axial momentum of the compressor blade tip and widening the stability margin through casing treatment, blade tip injection, etc. have been widely verified, they still face many challenges in balancing efficiency and stability margin. How to effectively control the double leakage flow at the blade tip without increasing the complexity of the blade tip structure, improve the axial momentum of the blade tip area, and at the same time take into account efficiency and stability margin is a technical problem that needs to be urgently solved in the current field of high-load compressor design. Summary of the Invention

[0005] (1) Purpose of the invention

[0006] To address the aforementioned deficiencies and shortcomings of the prior art, such as the complexity of blade tip geometry caused by casing treatment and tip injection, the induction of strong turbulent mixing and aerodynamic losses, and the difficulty in balancing efficiency and stability margins, the present invention addresses at least one of these and other technical issues in the prior art and effectively controls compressor tip double leakage and stability margins. Starting from the underlying physical mechanism of enhancing blade tip axial momentum, the present invention proposes a blade tip shaping method featuring a convex pressure surface belly. By generating a three-dimensional convex structure locally on the pressure surface, the pressure field in the blade tip region is reconstructed, ultimately enhancing the axial momentum in the tip vortex-vortex interference region and effectively reducing double leakage intensity and the resulting aerodynamic blockage. Compared to casing treatment and tip injection methods, the present invention's method based on localized tip pressure surface shaping offers greater design freedom and a simpler structure. Furthermore, it avoids inducing excessive turbulent mixing, which can lead to efficiency losses. This method provides direct support for double leakage control and refined blade tip design in high-load compressors.

[0007] (2) Technical solution

[0008] In order to achieve the purpose of the invention and solve the technical problems, the present invention adopts the following technical solutions:

[0009] The present invention aims to propose a blade shaping method featuring a raised pressure surface belly, designed to achieve dual-leakage control in compressor blade tips. The key to this method lies in the design of a three-dimensional raised structure and pressure field reconstruction in the core region of the double-leakage vortex-vortex interference at the blade tip. The main steps and corresponding solutions are as follows:

[0010] A blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor is used to enhance the axial momentum of the blade tip and weaken the intensity of double leakage and the aerodynamic blockage induced by it, thereby improving the aerodynamic efficiency and stability margin of the compressor. The blade shaping method, when implemented, includes at least the following steps:

[0011] SS1. A high-load compressor blade was selected as a reference blade for optimization and modification. CFD numerical calculations were performed on this high-load compressor blade. By adjusting the tip clearance and flow coefficient, the formation of vortex chains induced by tip vortex-vortex interference under double leakage conditions and their location of intrusion into adjacent blade passages were determined. The core region of low axial momentum at the blade tip induced by double leakage was identified.

[0012] SS2. Based on the numerical calculation results of the double leakage-induced vortex-vortex interference in step SS1, a two-dimensional local protrusion structure is designed on the pressure surface of the reference blade. The parametric modeling of the two-dimensional local protrusion structure is completed using a sinusoidal expression, where the size of the two-dimensional local protrusion is expressed as:

[0013]

[0014] Where d(x) is the size of the local bulge, A is the peak value of the local bulge, x is the flow direction coordinate of the local bulge, x1 and x2 are the flow starting position and flow ending position of the local bulge respectively;

[0015] SS3. Project the sinusoidal two-dimensional local convex structures at different flow direction positions designed in step SS2 onto the reference blade pressure surface along the local normal direction to achieve a two-dimensional local convex shape on the reference blade pressure surface:

[0016]

[0017] Where B' is the coordinate point of the modified blade after the normal superposition of the two-dimensional bulge, B is the coordinate point of the reference blade, are the vectors from the origin O to the reference blade surface coordinate point B and the modified blade surface coordinate point B', respectively. is the local unit normal vector of the reference blade surface;

[0018] SS4. Based on the parameterized expression for the two-dimensional localized convex shape on the pressure surface of the reference blade determined in steps SS2 and SS3, perform two-dimensional localized convex shape on the pressure surface of the reference blade at different spanwise locations. The parameter configuration and spanwise stacking characteristics of the two-dimensional localized convex shape at each spanwise location are individually set to construct a three-dimensional convex shape structure on the belly of the blade tip pressure surface modified from the reference blade.

[0019] SS5. Compare the load distribution and time-averaged velocity distribution of the blade tips of the baseline blade and the modified blade to verify the control effect of the belly bulge on the pressure surface of the modified blade on double leakage, confirm whether it effectively enhances the axial momentum of the blade tip and whether it suppresses double leakage from invading the core leakage area of ​​the adjacent blade. If the control effect requirements are met, the modified blade is used as the final design scheme. If the control effect requirements are not met, return to step SS4 and reconfigure the parameters and perform three-dimensional modeling based on the verification results until the performance of the modified blade meets the control effect requirements.

[0020] (3) Technical effects

[0021] Compared with the prior art, the blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor provided by the present invention has the following advantages:

[0022] (1) This invention reconstructs the pressure field in the blade tip region by designing a localized raised structure on the blade pressure surface, significantly enhancing the axial momentum of the blade tip. This effectively controls the double leakage flow at the blade tip of a high-load compressor, weakening the vortex-vortex interference and aerodynamic blockage caused by the double leakage phenomenon. This method directly targets the physical mechanism of double leakage flow and can significantly improve the aerodynamic efficiency and stability margin of the compressor, providing a new technical path for optimizing the performance of high-load compressors.

[0023] (2) The blade shaping method proposed in the present invention has the advantages of being simple in shape and not increasing the complexity of the blade tip geometry. The present invention proposes to provide a three-dimensional raised structure on the pressure surface of the blade tip to achieve dual leakage control. This method has a simple shape and not only maintains the relative simplicity of the blade tip geometry, but can also be directly incorporated into the full three-dimensional design system of the compressor blade without the need for additional auxiliary structures and equipment, greatly simplifying the blade tip design process. This not only reduces manufacturing costs but also improves the actual application performance of the blade.

[0024] (3) The control parameters are easy to adjust and the design freedom is high. Based on the parametric expression of the pressure surface belly bulge configuration, the present invention can achieve rapid adjustment of the bulge peak, spatial position and spanwise stacking mode, thereby obtaining different types of pressure surface belly bulges to meet different working conditions and design requirements. Compared with traditional methods, this method has a higher degree of design freedom. In theory, combined with the optimization strategy, the bulge shape corresponding to the best control effect can be obtained.

[0025] (4) The physical meaning is clear, and the control results take into account both efficiency and stability margin. Starting from the underlying physical mechanism of double leakage control, which is to increase the axial momentum of the blade tip, the present invention proposes a blade tip shaping method with the bulge of the pressure surface belly as the main feature. By reorganizing the blade tip pressure field, the axial momentum near the pressure surface is enhanced, thereby achieving double leakage control. Compared with casing treatment, blade tip injection, etc., this method can not only weaken the vortex-vortex interference and aerodynamic blockage intensity induced by double leakage, but also avoid inducing excessive turbulent mixing and resulting in a decrease in efficiency, and has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to the present invention;

[0027] Figure 2 Schematic diagram of the two-dimensional belly convex cross section of the pressure surface in the present invention;

[0028] Figure 3 Schematic diagram of the convex cross-section of the pressure surface at different spanwise positions near the blade tip in the present invention, (a) is the starting section, (b) is the spanwise section 1, (c) is the spanwise section 2, and (d) is the blade tip section;

[0029] Figure 4 Schematic diagram comparing the tip load distribution of the reference blade and the modified blade in the present invention;

[0030] Figure 5 Schematic diagram comparing the time-averaged velocity distribution at the blade tip of the reference blade (a) and the modified blade (b). DETAILED DESCRIPTION

[0031] In order to better understand the present invention, the contents of the present invention are further explained in conjunction with the embodiments below. In the accompanying drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be understood as limiting the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The structure and technical solution of the present invention are further described in detail below in conjunction with the accompanying drawings, and an embodiment of the present invention is given.

[0032] Starting from the underlying physical mechanism of enhancing the axial momentum of the blade tip, the present invention proposes a blade tip shaping method with the bulge on the belly of the pressure surface as the main feature. By generating a three-dimensional bulge structure at a local position on the pressure surface, the pressure field reconstruction of the blade tip area is achieved, and the axial momentum of the blade tip vortex-vortex interference area is ultimately enhanced, effectively weakening the double leakage intensity and the aerodynamic blockage induced by it. Compared with methods such as casing processing and blade tip injection, the method based on local shaping of the blade tip pressure surface of the present invention has a high degree of design freedom and a simple structure; at the same time, it avoids inducing excessive turbulent mixing and causing a decrease in efficiency, providing direct support for the double leakage control of high-load compressors and the refined design of blade tips.

[0033] As a specific example, Figure 1 As shown, the blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor of the present invention comprises at least the following steps when implemented:

[0034] SS1. Select a reference blade and perform CFD simulation

[0035] A high-load compressor blade was selected as a reference blade for optimization and modification, and CFD numerical calculations were performed on this high-load compressor blade to extract blade tip flow field information, providing the prerequisites for double leakage control. By adjusting the tip clearance size and flow coefficient, the time-averaged pressure field (or time-averaged velocity field) and turbulence statistical characteristics (Reynolds stress, turbulent kinetic energy, etc.) at the blade tip under different operating conditions were compared. The formation of vortex chains induced by blade tip vortex-vortex interference under double leakage conditions and their intrusion into adjacent blade channels were determined. The intersection of the double leakage trajectory and the adjacent blade pressure surface was determined, and the core area of ​​low axial momentum at the blade tip induced by double leakage was obtained.

[0036] In some preferred examples, when carrying out CFD numerical calculations, a high-precision large eddy simulation (LES) solver can be used, the WALE model is selected as the sub-grid model, and grid encryption processing is used in the blade tip clearance area, where the blade tip clearance value range is 0.5% to 5% of the blade height, and the flow coefficient value range is 0.3 to 0.6. By adjusting the blade tip clearance and the flow coefficient, the time-averaged pressure field or time-averaged velocity field and the turbulence statistical characteristics of the blade tip under different working conditions are compared, and the position of the vortex chain induced by the blade tip vortex-vortex interference under double leakage conditions and its invasion into the adjacent blade channel is clarified, the intersection position of the double leakage trajectory and the adjacent blade pressure surface is determined, and the core area of ​​low axial momentum of the blade tip induced by double leakage is identified.

[0037] In addition, by analyzing the axial velocity distribution in the blade tip area, for example, the area where the axial velocity is 10% lower than the average value can be defined as the low axial momentum core area. Combined with the position of the blade tip vortex-vortex interference area, the generation and transport path of the double leakage induced vortex chain can be clarified to identify the key areas of the blade tip double leakage flow, providing reliable basic data for the subsequent local bulge structure design.

[0038] SS2. Design of sinusoidal two-dimensional local convex structures

[0039] According to the numerical calculation results of the double leakage induced vortex-vortex interference in step SS1, a sinusoidal expression is used to complete the parametric modeling of the two-dimensional local bulge on the pressure surface. The size of the local bulge is as follows:

[0040]

[0041] In the above formula, d(x) is the size of the local bump, A is the peak value of the local bump, x is the flow direction coordinate of the local bump, and x1 and x2 are the starting and ending positions of the flow direction of the local bump, respectively.

[0042] In some preferred embodiments, the parametric design of the two-dimensional local protrusion structure also includes determining the flow coverage range and peak size of the local protrusion, wherein the flow coverage range of the local protrusion is preferably 25% to 65% of the chord length, and the height peak A of the local protrusion is preferably 10% to 30% of the maximum thickness of the blade. Through parametric design, the shape and size of the protrusion can be flexibly adjusted to adapt to different double leakage flow characteristics. At the same time, in order to ensure a smooth transition between the local protrusion and the reference blade profile, a third-order spline curve is preferably used to connect the two end points x1 and x2 of the local protrusion to ensure the curvature continuity between the local protrusion and the reference blade profile.

[0043] Figure 2 The profiles of the two-dimensional local bulge under different parameter configuration conditions are compared. It can be seen from the figure that the two-dimensional local bulge reaches its peak at the middle flow position.

[0044] SS3. 2D Local Raised Shape Projection

[0045] The sinusoidal two-dimensional convex structure designed in step SS2 at different flow direction positions is projected onto the reference blade pressure surface along the local normal direction to complete the two-dimensional local convex shape of the reference blade pressure surface. The method is as follows:

[0046]

[0047] Where B' is the coordinate point of the modified blade after the normal superposition of the two-dimensional bulge, B is the coordinate point of the reference blade, are the vectors from the origin O to the coordinate point B on the reference blade surface and the left point B' on the modified blade surface, respectively. is the local unit normal vector of the reference blade surface.

[0048] In some preferred embodiments, when performing normal projection of a two-dimensional local convex structure, an iterative method is used to perform projection calculation for regions with larger curvatures. First, the two-dimensional local convex structure is preliminarily projected onto the pressure surface of the reference blade. According to the calculation formula Calculate the initial position of each projected point After the initial projection is completed, the curvature of each projected point and its neighboring points is calculated and the curvature error ΔK is evaluated. For the projected points whose curvature error ΔK exceeds the set threshold ∈, its normal position is iteratively adjusted until the curvature continuity requirement is met. In each iteration, the normal correction vector is calculated according to the current curvature error direction. And according to Update the projection point position, where α is the adjustment step size to avoid projection distortion in high curvature areas.

[0049] SS4. Constructing 3D modeling structures

[0050] According to the parametric expression of the two-dimensional local convex shape of the pressure surface of the reference blade determined in the above steps SS2 and SS3, two-dimensional local convex shape is performed on the pressure surface of the reference blade at different spanwise positions, and the parameter configuration and spanwise stacking characteristics of the two-dimensional local convex at each spanwise position are set one by one to construct a three-dimensional shape structure of the convex belly of the blade tip pressure surface that is modified from the reference blade.

[0051] In some preferred embodiments, multiple spanwise locations within the spanwise range of 90% to 100% of the blade height can be selected for two-dimensional localized protrusion shaping. By stacking the two-dimensional localized protrusion structures generated at each spanwise location along the center of gravity spanwise, a three-dimensional protrusion structure of the blade tip pressure surface belly portion, which is modified from the baseline blade, can be constructed. When constructing the three-dimensional protrusion structure of the blade tip pressure surface belly portion, a cubic spline interpolation method is preferably used to connect the two-dimensional localized protrusion contours at each spanwise location to form a continuous and smooth three-dimensional protrusion structure, thereby reducing potential additional flow losses. Further preferably, the selected spanwise locations near the blade tip include, but are not limited to, 90%, 93%, 96%, and 100% of the blade height. For each selected spanwise location, the structural parameters of the two-dimensional localized protrusion are set, including at least the center position of the two-dimensional localized protrusion, the flow direction starting position x1, the flow direction ending position x2, and the peak height A. When determining these structural parameters, the characteristics of the double leakage flow and the variation trend of the intensity along the spanwise direction should be considered, so that the two-dimensional localized protrusion structure can effectively regulate the double leakage flow at different spanwise locations.

[0052] More specifically, Figure 3 A convex shape scheme is given. The three-dimensional shape of the belly convex shape starts from 90% of the blade height (also known as the "starting section"); at the 93% section (also known as the "spanwise section 1"), a sinusoidal convex structure is symmetrically covered along the flow direction on the pressure surface with the vortex-vortex interference area as the center. Among them, the convex peak A is taken as the maximum blade thickness t max 20% of the chord length, the position is from 25% to 65% of the chord length; at the 96% section (also known as "span-wise section 2"), the convex peak A increases to the maximum thickness of the blade t max 30% of the blade, the flow distribution position remains unchanged; at the blade top section, the convex peak A is the maximum thickness of the blade t max After obtaining the two-dimensional convex sections at various spanwise locations near the blade tip, the blade tip is radially stacked along the center of gravity to obtain a three-dimensional geometric structure with the convex pressure surface belly as the main feature, completing the blade shape.

[0053] SS5. Verify the performance of modified blades

[0054] Compare the load distribution and time-averaged velocity distribution of the blade tips of the baseline blade and the modified blade to verify the control effect of the belly bulge on the pressure surface of the modified blade on double leakage, confirm whether it effectively enhances the axial momentum of the blade tip and whether it suppresses double leakage from invading the core leakage area of ​​the adjacent blade. If the control effect requirements are met, the modified blade will be used as the final design scheme. If the control effect requirements are not met, return to step SS4 and re-configure the parameters and three-dimensional modeling according to the verification results until the performance of the modified blade meets the control effect requirements.

[0055] As a specific example, in order to verify the control effect of the above blade tip three-dimensional geometric modeling on double leakage, Figure 4 The tip load distribution of a baseline blade and a modified blade with a certain parameter configuration was compared. In terms of suction surface load distribution, there was no significant difference between the baseline and modified blades. However, the belly bulge on the pressure side of the modified blade caused the airflow to accelerate rapidly starting near 28% of the axial chord length, reaching a peak at 38% of the axial chord length, and then decelerating under a strong adverse pressure gradient. Compared to the baseline blade, the belly bulge on the pressure side significantly changed the local pressure gradient distribution, which will have a significant impact on the dynamic process of double leakage at the blade tip and the low axial momentum region induced by vortex-vortex interference.

[0056] Figure 5 The time-averaged velocity distributions of the blade tips of the baseline and modified blades were further compared (dimensionlessized using the inlet velocity of each). A clear double leakage phenomenon appeared in the rear half of the pressure surface of the baseline blade. Vortex-vortex interference formed a vortex chain, which invaded the leakage core area near the suction surface of the adjacent blade, inducing vortex breakup. This caused the low axial momentum area to expand rapidly, exacerbating the blockage and becoming a key factor in inducing aerodynamic instability at the compressor blade tip. For the modified blade, the bulge on the belly of the pressure surface induced a sharp acceleration of the local airflow, increased axial momentum, and pushed the leakage flow-mainstream interface downstream, effectively suppressing the double leakage near the pressure surface from invading the core leakage area of ​​the adjacent blade. Therefore, the vortex-vortex interference and vortex breakup intensity caused by double leakage were greatly weakened, the blade tip recirculation area was significantly reduced, and the local flow performance was enhanced, which is of great significance for widening the blade tip stability margin.

[0057] In some preferred examples, when verifying the modification effect, multiple operating points are selected within the range of 80% to 120% of the design point flow rate for numerical simulation, and the performance changes of the blades under different operating conditions before and after the modification are analyzed. By comparing the double leakage trajectories before and after the modification and the induced low axial momentum core area of ​​the blade tip, the improvement effect of the modification on the stable operating margin of the high-load compressor is verified.

[0058] The above embodiments fully and effectively achieve the objectives of the present invention. Those skilled in the art will appreciate that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the above specific embodiments. Although the present invention has been described with reference to the embodiments currently considered to be the most practical and preferred, it should be understood that the present invention is not limited to the disclosed embodiments, and any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor, characterized in that: The blade shaping method comprises at least the following steps when implemented: SS1. A high-load compressor blade was selected as a reference blade for optimization and modification. CFD numerical calculations were performed on this high-load compressor blade. By adjusting the tip clearance and flow coefficient, the formation of vortex chains induced by tip vortex-vortex interference under double leakage conditions and their location of intrusion into adjacent blade passages were determined. The core region of low axial momentum at the blade tip induced by double leakage was identified. SS2. Based on the numerical calculation results of the double leakage-induced vortex-vortex interference in step SS1, a two-dimensional local protrusion structure is designed on the pressure surface of the reference blade. The parametric modeling of the two-dimensional local protrusion structure is completed using a sinusoidal expression, where the size of the two-dimensional local protrusion is expressed as: Where d(x) is the size of the local bulge, A is the peak value of the local bulge, x is the flow direction coordinate of the local bulge, x1 and x2 are the flow starting position and flow ending position of the local bulge respectively; SS3. Project the sinusoidal two-dimensional local convex structures at different flow direction positions designed in step SS2 onto the reference blade pressure surface along the local normal direction to achieve a two-dimensional local convex shape on the reference blade pressure surface: Where B' is the coordinate point of the modified blade after the normal superposition of the two-dimensional bulge, B is the coordinate point of the reference blade, are the vectors from the origin O to the reference blade surface coordinate point B and the modified blade surface coordinate point B', respectively. is the local unit normal vector of the reference blade surface; SS4. Based on the parameterized expression for the two-dimensional localized convex shape on the pressure surface of the reference blade determined in steps SS2 and SS3, perform two-dimensional localized convex shape on the pressure surface of the reference blade at different spanwise locations. The parameter configuration and spanwise stacking characteristics of the two-dimensional localized convex shape at each spanwise location are individually set to construct a three-dimensional convex shape structure on the belly of the blade tip pressure surface modified from the reference blade. SS5. Compare the load distribution and time-averaged velocity distribution of the blade tips of the baseline blade and the modified blade to verify the control effect of the belly bulge on the pressure surface of the modified blade on double leakage, confirm whether it effectively enhances the axial momentum of the blade tip and whether it suppresses double leakage from invading the core leakage area of ​​the adjacent blade. If the control effect requirements are met, the modified blade is used as the final design scheme. If the control effect requirements are not met, return to step SS4 and reconfigure the parameters and perform three-dimensional modeling based on the verification results until the performance of the modified blade meets the control effect requirements.

2. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 1, characterized in that: In the above step SS1, the CFD numerical simulation adopts a high-precision large eddy simulation (LES) solver, the sub-grid model adopts the WALE model, and the grid encryption processing is adopted in the blade tip clearance area, where the blade tip clearance value range is 0.5% to 5% of the blade height, and the flow coefficient value range is 0.3 to 0.

6. By adjusting the blade tip clearance and the flow coefficient, the time-averaged pressure field or the time-averaged velocity field and the turbulence statistical characteristics of the blade tip under different working conditions are compared, and the position of the vortex chain induced by the blade tip vortex-vortex interference and its invasion into the adjacent blade channel under the double leakage condition is clarified, the intersection position of the double leakage trajectory and the adjacent blade pressure surface is determined, and the core area of ​​the blade tip low axial momentum induced by the double leakage is identified.

3. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 2, characterized in that: In the above step SS1, by analyzing the axial velocity distribution in the blade tip area, the area where the axial velocity is 10% lower than the average value is defined as the low axial momentum core area. Combined with the position of the blade tip vortex-vortex interference area, the generation and transport path of the double leakage induced vortex chain are clarified to identify the key area of ​​the blade tip double leakage flow.

4. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 1, characterized in that: In the above step SS2, the parametric design of the two-dimensional local protrusion structure also includes determining the flow direction coverage range and peak size of the local protrusion, wherein the flow direction coverage range of the local protrusion is 20% to 70% of the chord length, and the height peak A of the local protrusion is 10% to 30% of the maximum thickness of the blade. At the same time, a third-order spline curve is used to connect the two end points x1 and x2 of the local protrusion to ensure the curvature continuity between the local protrusion and the reference blade profile.

5. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 1, characterized in that: In the above step SS3, when performing the normal projection of the two-dimensional local convex structure, the iterative method is used to perform the projection calculation for the area with larger curvature. First, the two-dimensional local convex structure is preliminarily projected onto the pressure surface of the reference blade. According to the calculation formula Calculate the initial position of each projected point After the initial projection is completed, the curvature of each projected point and its neighboring points is calculated and the curvature error ΔK is evaluated. For the projected points whose curvature error ΔK exceeds the set threshold ∈, its normal position is iteratively adjusted until the curvature continuity requirement is met. In each iteration, the normal correction vector is calculated according to the current curvature error direction. And according to Update the projection point position, where α is the adjustment step size to avoid projection distortion in high curvature areas.

6. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 1, characterized in that: In the above step SS4, multiple different spanwise positions within the spanwise range of 90% to 100% of the blade height are selected for two-dimensional local convex modeling, and the two-dimensional local convex structures generated at each spanwise position are stacked along the spanwise direction of the center of gravity to construct a three-dimensional modeling structure of the convex belly of the blade top pressure surface that is modified from the reference blade.

7. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 6, characterized in that: In the above step SS4, when constructing the three-dimensional convex structure of the blade tip pressure surface belly, the cubic spline interpolation method is used to connect the two-dimensional local convex contours at each span position to form a continuous and smooth three-dimensional convex structure to reduce the possible additional flow loss.

8. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 6 or 7, characterized in that: In the above step SS4, the selected spanwise positions near the blade top include but are not limited to 90%, 93%, 96% and 100% of the blade height, and the structural parameters of the two-dimensional local protrusion are set for each selected spanwise position, including at least the center position of the two-dimensional local protrusion, the flow starting position x1, the flow ending position x2 and the height peak A, and when determining these structural parameters, the characteristics of the double leakage flow and the intensity variation trend in the spanwise direction should be considered, so that the two-dimensional local protrusion structure can effectively regulate the double leakage flow at different spanwise positions.

9. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 8, characterized in that: In the above step SS4, the three-dimensional shape of the belly bulge is generated starting from 90% of the blade height. At the spanwise position, with the vortex-vortex interference zone as the center, a sinusoidal bulge structure is symmetrically covered along the flow direction of the pressure surface: at the 90% blade height section, the bulge peak A is 0; at the 93% blade height section, the bulge peak A is the maximum blade thickness t max The flow direction covers the range from 25% chord length to 65% chord length; at the 96% blade height section, the convex peak A is the maximum blade thickness t max The flow direction coverage range is from 25% chord length to 65% chord length; at 100% blade tip section, the convex peak A is the maximum blade thickness t max The flow direction covers the range from 23% chord length to 67% chord length.

10. The blade shaping method for controlling double leakage flow at the blade tip of a high-load compressor according to claim 1, characterized in that: In step SS5 above, when verifying the modification effect, multiple operating points are selected within the range of 80% to 120% of the design point flow rate for numerical simulation, and the performance changes of the blades under different operating conditions before and after the modification are analyzed. By comparing the double leakage trajectories before and after the modification and the induced low axial momentum core area of ​​the blade tip, the improvement effect of the modification on the stable operating margin of the high-load compressor is verified.

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