Turbine guide blade stress relief structure and preparation method thereof

Abstract

The invention discloses a turbine guide blade stress relief structure and a preparation method thereof.The turbine guide blade stress relief structure comprises a turbine blade body, an upper edge plate arranged on the upper portion of the turbine blade body and a lower edge plate arranged on the lower portion of the turbine blade body, the turbine blade body is provided with a blade tail edge, and the joint of the blade tail edge and the upper edge plate is a switching R area; the side edge, close to the transfer R area, of the upper edge plate is an exhaust edge, and a plurality of U-shaped groove structures are arranged on the exhaust edge at intervals. By introducing the U-shaped groove structure, the rigid barrier of the traditional solid structure is broken, the stress at the transfer R position is reduced, and the local stress peak value is avoided. The composite wire notch and the micro-rounding strengthening area cooperate to eliminate the geometric mutation of the notch and avoid the secondary stiffness gradient problem caused by the design of a U-shaped groove.

Description

Technical Field

[0001] The present invention relates to the technical field of aero engines and gas turbines, and in particular to a turbine guide blade stress relief structure and a preparation method thereof. Background Art

[0002] Turbine guide vanes are key components in the turbines of thermal power plants such as aircraft engines and gas turbines. The upper plate overlap of the turbine guide vane primarily refers to the connection area with the outer casing, rear sealing ring, or other structural components. This overlap area must withstand the impact and vibration loads of high-temperature combustion gases. While traditional solid structures can ensure strength, the difference in stiffness with the hollow blade body leads to stress concentration in the transition R region, making it a high-risk area for fatigue failure. The sudden change in stiffness causes stress concentration in the transition area between the upper plate and the blade body, making fatigue cracks prone to occur during the test run.

[0003] Existing technologies mainly relieve stress through local geometric strengthening (such as rounding and thickening), but due to process and functional requirements, the effect is limited, and the stress relief rate is no more than 10%. In addition, thickening the trailing edge of the blade not only increases the weight of the blade, but may also affect the aerodynamic performance of the blade. Summary of the Invention

[0004] In view of this, the present invention provides a turbine guide blade stress relief structure and a preparation method thereof to solve the problem that fatigue cracks are easily generated during the test run due to stress concentration in the transition area between the upper edge plate and the blade body of the turbine guide blade due to sudden change in stiffness.

[0005] The present invention provides a turbine guide blade stress relief structure, comprising a turbine blade body, an upper edge plate arranged at the upper portion of the turbine blade body, and a lower edge plate arranged at the lower portion of the turbine blade body, wherein the turbine blade body has a blade trailing edge, and the intersection of the blade trailing edge and the upper edge plate is a transition R region;

[0006] One side of the upper edge plate close to the transition R region is an exhaust edge, and a plurality of U-shaped groove structures are arranged at intervals on the exhaust edge.

[0007] The beneficial effect of the turbine guide vane stress relief structure is that, by placing U-shaped grooves at intervals along the exhaust edge, the local stiffness of the upper edge plate is reduced, narrowing the stiffness difference between the upper edge plate and the turbine blade body, thereby effectively alleviating stress concentration in the transition R region. Compared to existing technologies, the U-shaped groove structure achieves more significant stress reduction through stiffness regulation, significantly suppressing the initiation and propagation of fatigue cracks and extending blade life.

[0008] The U-shaped groove structure of the present invention achieves weight reduction while ensuring structural strength by removing redundant materials, which not only meets the lightweight requirements but also avoids the negative impact of thermal and aerodynamic performance caused by thickening.

[0009] In an optional embodiment, the U-shaped groove structure includes a groove bottom, a first groove wall, and a second groove wall. The first groove wall and the groove bottom are connected by a first groove transition area, and the second groove wall and the groove bottom are connected by a second groove transition area. The first groove wall, the first groove transition area, the groove bottom, the second groove transition area and the second groove wall are connected to form a U-shaped structure.

[0010] In an optional embodiment, the distance between the bottom of the groove and the exhaust edge is the height of the U-shaped groove, the height of the U-shaped groove is H, and H is 1.5 to 5 mm; and / or

[0011] The first notch transition area and the second notch transition area are both arcs, the radius of the first notch transition area is R1, the radius of the second notch transition area is R2, R1=R2=(0.3-0.6)H; and / or

[0012] The distance between the first groove wall and the second groove wall is the U-shaped groove width, the U-shaped groove width is W, and the distance between two adjacent U-shaped groove structures is L, W≤0.7L;

[0013] The thickness of the U-shaped groove structure is t, and t is 0.8 mm to 1.5 mm.

[0014] In an optional embodiment, the upper notch edge of the U-shaped groove and the lower notch edge of the U-shaped groove structure are both rounded, and the rounding radius is 0.2 mm to 0.5 mm.

[0015] In an optional embodiment, the upper notch edge of the U-shaped groove and the lower notch edge of the U-shaped groove structure are designed with a composite profile, including an elliptical transition section, a parabolic transition section or a combination of the two.

[0016] In an optional embodiment, the elliptical transition section satisfies the mathematical expression: 2 x 2 +b 2 y 2 =1, where a is the major axis of the ellipse, b is the minor axis of the ellipse, x is the horizontal coordinate variable, y is the vertical coordinate variable, a=0.8~1.5mm, b=0.3~0.6mm;

[0017] The parabolic transition section satisfies the mathematical expression: y=kx 2 , where x is the horizontal coordinate variable, y is the vertical coordinate variable, and k is the curvature coefficient, k = 0.05~0.15.

[0018] In an optional embodiment, the inner surface of the U-shaped groove structure is alternately arranged with arrayed micro-bosses and arrayed micro-pits; the arrayed micro-bosses include a plurality of spaced-apart micro-bosses, and the micro-bosses are suitable for inducing local micro-eddies, dispersing the macroscopic stress field, and reducing the main stress peak of the groove body; the arrayed micro-pits include a plurality of spaced-apart micro-pits, and the micro-pits are suitable for absorbing local stress peaks through plastic deformation.

[0019] In a second aspect, the present invention provides a method for preparing a turbine guide blade stress relief structure, comprising the following steps:

[0020] S1. Split precision casting:

[0021] The turbine blade body and upper edge plate are divided into a base module and a U-shaped groove module;

[0022] S2. Module integration:

[0023] Connecting the base module to the U-shaped slot module by diffusion welding;

[0024] S3. Composite post-processing strengthening process:

[0025] Laser shock peening is performed on the U-groove structure to induce a surface residual compressive stress layer;

[0026] Electrolytic polishing of the inner surface of the U-shaped groove structure;

[0027] The U-shaped groove structure is subjected to microparticle shot peening treatment.

[0028] In an optional embodiment, the base module is prepared by directional solidification casting technology; and / or

[0029] The U-shaped groove module is prepared by 3D printing ceramic core + directional solidification technology, and the negative mold structure of micro-convex platforms and micro-pits is etched on the surface of the ceramic core.

[0030] In an optional embodiment, the pouring temperature of the directional solidification casting is controlled above the solidus line of the alloy, and a gradient cooling strategy is adopted in the cooling process to ensure that the U-shaped groove structure area solidifies preferentially.

[0031] In summary, the technical solution of the present invention has the following advantages:

[0032] By introducing a U-shaped groove structure, this invention breaks the rigidity barrier of traditional solid structures, reduces stress at the transition R, and avoids local stress peaks. The composite linear notch and micro-rounded reinforcement area work together to eliminate geometric changes in the notch and avoid the secondary stiffness gradient problem caused by the U-shaped groove design.

[0033] The U-shaped groove of the present invention removes redundant materials, reducing weight by more than 5% compared to traditional thickening solutions, and the stiffness control design does not require additional reinforcement structure, breaking the contradiction between weight increase and stress relief. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A schematic structural diagram of a turbine guide blade stress relief structure provided by the present invention;

[0036] Figure 2 A schematic cross-sectional view of a U-shaped groove structure in a turbine guide blade stress relief structure provided by the present invention;

[0037] Figure 3 A schematic diagram of a U-shaped groove transition area in a turbine guide blade stress relief structure provided by the present invention;

[0038] Figure 4 A schematic diagram of the elliptical and parabolic transition regions in a turbine guide blade stress relief structure provided by the present invention;

[0039] Figure 5 A schematic diagram of the transition region of the elliptical and parabolic composite profiles in a turbine guide blade stress relief structure provided by the present invention;

[0040] Figure 6 A schematic diagram of the distribution of arrayed micro-bosses and arrayed micro-pits in a turbine guide blade stress relief structure provided by the present invention.

[0041] Description of reference numerals:

[0042] 1. Turbine blade body, 11. Blade trailing edge, 2. Upper edge plate, 21. Exhaust edge, 22. U-shaped groove structure, 221. Groove bottom, 222. First groove wall, 223. Second groove wall, 224. First groove transition area, 225. Second groove transition area, 226. U-shaped groove upper groove edge, 227. U-shaped groove lower groove edge, 3. Lower edge plate, 4. Transition R area, 5. Micro-boss, 6. Micro-pit, H, U-shaped groove height, R1, first arc radius, R2, second arc radius, W, U-shaped groove width, t, U-shaped groove thickness, L, spacing between two adjacent U-shaped groove structures, D, spacing between two adjacent micro-boss or micro-pits. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0044] The transition area between the upper edge plate and the blade body of a conventional turbine guide vane causes stress concentration due to a sudden change in stiffness, which can easily cause fatigue cracks during test runs. Existing technologies alleviate stress concentration through local rounding and thickening of the trailing edge, but these technologies have the following core drawbacks:

[0045] Insufficient stress relief: The fillet reinforcement is limited by the installation space, and the fillet radius cannot exceed the critical value, resulting in the stress concentration factor remaining at a high level and limited improvement in fatigue life; although the thickening of the blade trailing edge can reduce the local stress peak, the thickened area and the adjacent area form a new stiffness mutation, causing secondary stress concentration.

[0046] Weight-to-thermal performance conflict: Thickening significantly increases the weight of the upper edge, conflicting with the engine's lightweighting requirements. Furthermore, the thickened area impedes heat conduction, leading to significant localized temperature rises under high-temperature conditions and accelerating material degradation. Thickening the trailing edge not only increases blade weight but also potentially impacts aerodynamic performance.

[0047] Based on this, the present invention provides a turbine guide blade stress relief structure. To address the problem of excessive stress in the transition area between the exhaust edge of the upper edge plate of the turbine blade and the blade body, the present invention proposes a new edge plate exhaust edge structure, introduces a U-shaped groove stiffness control structure, and performs stress reduction design on the U-shaped groove structure to avoid the secondary stiffness mutation problem caused by grooving.

[0048] The following combination Figures 1 to 6 , the turbine guide blade stress relief structure of the first aspect of the present invention and the preparation method of the turbine guide blade stress relief structure of the second aspect of the present invention are elaborated in detail.

[0049] According to an embodiment of the present invention, in a first aspect, a turbine guide vane stress relief structure is provided, comprising a turbine blade airfoil 1, an upper edge plate 2 disposed above the turbine blade airfoil 1, and a lower edge plate 3 disposed below the turbine blade airfoil 1. The turbine blade airfoil 1 has a trailing edge 11, and the intersection of the trailing edge 11 and the upper edge plate 2 forms a transition R region 4. A side edge of the upper edge plate 2 adjacent to the transition R region 4 forms an exhaust edge 21, on which a plurality of U-shaped groove structures 22 are arranged at intervals.

[0050] The radius of the fillet (R) in the transition R region 4 is typically 0.5mm to 3mm. However, due to installation space limitations, the fillet radius cannot exceed the critical value, resulting in a high stress concentration factor. Therefore, the vent edge 21 of the upper edge plate 2 is modified from a solid structure to a U-shaped groove structure 22. This reduces the stiffness of the vent edge 21, and stress analysis significantly reduces the stress level in the transition R region. Furthermore, to avoid secondary stiffness changes caused by notching, a circular arc transition groove bottom and a composite profile transition groove opening are designed to reduce local stress.

[0051] This embodiment reduces the local stiffness of the upper edge plate 2 by placing U-shaped groove structures 22 at intervals along the exhaust edge, narrowing the stiffness difference between the upper edge plate 2 and the turbine blade airfoil 1, thereby effectively alleviating stress concentration in the transition R region. Compared to existing technologies, the U-shaped groove structures 22 achieve more significant stress reduction through stiffness regulation, significantly suppressing the initiation and propagation of fatigue cracks and extending blade life.

[0052] Conventional technologies alleviate stress by thickening the trailing edge, which significantly increases blade weight. The thickened area can also hinder heat conduction and exacerbate high-temperature material degradation. The U-shaped groove structure of this embodiment eliminates redundant material (grooving the exhaust edge) to reduce weight while maintaining structural strength. This not only meets lightweight requirements but also avoids the negative impact on thermal and aerodynamic performance caused by thickening.

[0053] In some embodiments, the U-shaped groove structure 22 includes a groove bottom 221, a first groove wall 222, and a second groove wall 223. The first groove wall 222 and the groove bottom 221 are connected by a first groove transition area 224, and the second groove wall 223 and the groove bottom 221 are connected by a second groove transition area 225. The first groove wall 222, the first groove transition area 224, the groove bottom 221, the second groove transition area 225 and the second groove wall 223 are connected to form a U-shaped structure.

[0054] like Figure 2 The U-groove cross-section diagram shown in the figure shows the distance between the groove bottom 221 and the end face of the exhaust edge 21, which is the U-groove height, H. If the U-groove height is too low, it will not be possible to overlap and position the blade, and the stiffness change will not be obvious. If the U-groove height is too high, the exhaust edge will lack structural strength. Based on engineering experience, the U-groove height H is within the range of 1.5 to 5 mm. This range balances stiffness control and structural strength requirements, ensuring that the U-groove can relieve stress without affecting the overall reliability of the blade.

[0055] The first groove wall 222 and the second groove wall 223 transition to the groove bottom 221 via circular arcs. That is, both the first groove transition area 224 and the second groove transition area 225 are circular arcs. The radius of the first groove transition area 224 is R1, and the radius of the second groove transition area 225 is R2. To ensure symmetry and a smooth transition, R1 = R2 = (0.3-0.6)H. The symmetrical arcs connecting the groove wall and the groove bottom eliminate the geometric abruptness of traditional right-angle transitions, resulting in more uniform stress distribution.

[0056] The spacing between the first groove wall 222 and the second groove wall 223 is the U-groove width, where the U-groove width is W and the spacing between two adjacent U-groove structures is L. The U-groove width generally cannot be greater than 0.7 times the spacing between the two U-groove structures, i.e., W ≤ 0.7L, to ensure the strength of the U-groove structure. By limiting the ratio of the groove width to the spacing between adjacent grooves, local structural weakness caused by excessive groove width is avoided, while the connection strength of the base between grooves is guaranteed, preventing the problem of stress superposition between multiple grooves caused by too small groove spacing, further improving structural safety.

[0057] like Figure 3 The schematic diagram of the transition area of ​​the U-shaped groove is shown. According to engineering experience, the thickness t of the U-shaped groove structure 22 is generally in the range of 0.8mm to 1.5mm.

[0058] The upper notch edge 226 and the lower notch edge 227 of the U-shaped notch structure 22 need to have a smooth transition. There are two solutions based on the exhaust edge size and structural strength requirements:

[0059] 1) The upper and lower edges of the U-groove structure 22 are both rounded, with a radius of 0.2mm to 0.5mm. This smooth arc connects the groove and the base, simplifying the manufacturing process and reducing stress concentration at the groove edges, making it suitable for applications requiring less complex structures.

[0060] 2) The upper and lower edges of the U-shaped trough structure 22 utilize a composite profile design, including elliptical transition segments, parabolic transition segments, or a combination of the two. The use of parabolic and elliptical transitions at the trough edges allows for more flexible curvature variations. The major axis of the ellipse aligns with the load direction, enabling targeted optimization of the principal stress distribution. The parabola connects the trough wall, eliminating the sudden stress changes associated with traditional right-angle transitions.

[0061] The elliptical transition section satisfies the mathematical expression: a 2 x 2 +b 2 y 2 =1, where a is the major axis of the ellipse, b is the minor axis of the ellipse, x is the horizontal coordinate variable, y is the vertical coordinate variable, a=0.8~1.5mm, b=0.3~0.6mm.

[0062] The parabola transition section satisfies the mathematical expression: y = kx 2 , where x is the horizontal coordinate variable, y is the vertical coordinate variable, and k is the curvature coefficient, ranging from 0.05 to 0.15, to ensure a continuous and smooth transition. The curvature of the parabola changes, allowing for flexible adjustment of the steepness of the notch edge.

[0063] Alternatively, an elliptical-parabolic composite line can be used for transition, with a more flexible curvature change. The fatigue resistance can be enhanced by optimizing the local curvature to avoid cracks from initiating from the notch.

[0064] To further reduce the stress level of the U-shaped groove, an array of micro-bumps 5 and an array of micro-dimples 6 are arranged in the U-shaped groove structure (particularly in the groove bottom area). More specifically, the inner surface of the U-shaped groove structure 22 is alternately arranged with arrays of micro-bumps and micro-dimples. D is the distance between two adjacent micro-bumps or micro-dimples.

[0065] Hemispherical micro-bumps with a diameter of D = 0.2-0.5mm and a height of H = 0.1-0.3mm are arranged on the inner surface of the U-shaped groove (especially the groove bottom area). The spacing is regular: the center distance between adjacent micro-bumps is 1.5-2.0×D, and the row spacing is 1.2-1.5×D, ensuring a surface coverage rate of ≥40%. The micro-bump height is controlled within a specified range to ensure its effectiveness in boundary layer disturbance while avoiding a surge in flow resistance. The micro-bumps induce local micro-eddies, disperse the macroscopic stress field, and reduce the peak principal stress of the groove body.

[0066] Circular micro-pits with a depth of h = 0.1-0.2mm and a diameter of d = 0.2-0.4mm are set between the micro-convex platforms. The spacing between the micro-pits is consistent with the spacing between the micro-convex platforms, and local stress peaks are absorbed through plastic deformation.

[0067] According to an embodiment of the present invention, in a second aspect, a method for preparing a turbine guide blade stress relief structure is provided, comprising the following steps:

[0068] S1. Split precision casting:

[0069] The turbine blade airfoil 1 and upper edge plate 2 are divided into a base module and a U-groove module. The base module is manufactured using directional solidification casting technology to ensure overall strength. The U-groove module is produced using a 3D-printed ceramic core combined with directional solidification technology. The negative mold structure of micro-protrusions and pits is etched on the ceramic core surface. Split casting optimizes the process based on the characteristics of each module, ensuring that key parameters such as the U-groove height, width, and transition arc radius fully meet design requirements, providing a geometric foundation for subsequent stress relief effects.

[0070] The base module and the U-groove module are integrated by diffusion welding, and the welding interface is designed to be serrated to enhance the bonding strength and prevent cracks from extending across the interface.

[0071] The pouring temperature of directional solidification casting is controlled within a reasonable range above the alloy solidus to avoid core deformation due to overheating; a gradient cooling strategy is adopted in the cooling process to ensure that the trough area solidifies first and reduce residual stress.

[0072] S2. Composite post-processing strengthening process:

[0073] Laser shock peening (LSP) is performed on the U-shaped groove structure 22 to induce a surface residual compressive stress layer. More specifically, the laser shock peening (LSP) process selectively impacts the groove bottom and groove edges of the U-shaped groove structure to induce a surface residual compressive stress layer. The impact area and impact energy are dynamically adjusted based on the geometric gradient of the groove body to avoid deformation caused by excessive processing.

[0074] Then, the burrs on the inner surface of the groove are removed by electrolytic polishing (roughness Ra ≤ 0.4 μm), and then the bottom of the groove is locally shot peened using microparticle shot peening (particle size 50-100 μm) to further improve the surface integrity.

[0075] Preparation process:

[0076] Directional casting of base module → 3D printing ceramic core casting of U-groove module → diffusion welding → laser shock strengthening → electrolytic polishing.

[0077] The turbine guide vane stress relief structure introduces a U-shaped groove stiffness control structure on the exhaust edge of the solid upper plate. By designing a circular transition groove bottom and a composite profile transition groove, the local stiffness of the upper plate is reduced, significantly reducing stress in the transition area while avoiding the secondary stiffness mutation caused by the groove. Through the coordinated optimization of split casting and additive manufacturing processes, structural integrity is maintained while controlling weight, breaking through the technical bottleneck of traditional solid structures that cannot achieve both lightweight and low stress.

[0078] Stiffness-controlled U-shaped groove structure: Through the arc transition of the groove bottom and the composite curvature design of the groove edge, a continuous transition of the stiffness of the upper edge plate is achieved, reducing stress concentration at the transition R and inhibiting crack initiation.

[0079] Microstructure synergistic strengthening: The array of micro-convex platforms and micro-grooves in the groove disperses macroscopic stress and absorbs local energy.

[0080] Split casting and additive manufacturing process: Modular casting combined with 3D printing ceramic core technology to ensure process feasibility.

[0081] For a benchmark model of a turbine guide blade, the calculated transient maximum stress reached 1550 MPa. After iterative optimization of the design structure of the present invention, the transient maximum stress was reduced to 1270 MPa, a decrease of 18%, verifying that the present invention has important engineering application value.

[0082] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A turbine guide blade stress relief structure, comprising a turbine blade airfoil (1), an upper edge plate (2) arranged on the upper portion of the turbine blade airfoil (1), and a lower edge plate (3) arranged on the lower portion of the turbine blade airfoil (1), wherein the turbine blade airfoil (1) has a blade trailing edge (11), and the intersection of the blade trailing edge (11) and the upper edge plate (2) is a transition R region (4); It is characterized in that One side of the upper edge plate (2) close to the transition R region (4) is an exhaust edge (21), and a plurality of U-shaped groove structures (22) are arranged at intervals on the exhaust edge (21).

2. The turbine guide blade stress relief structure according to claim 1, characterized in that: The U-shaped groove structure (22) comprises a groove bottom (221), a first groove wall (222), and a second groove wall (223); the first groove wall (222) and the groove bottom (221) are connected via a first groove transition region (224); the second groove wall (223) and the groove bottom (221) are connected via a second groove transition region (225); the first groove wall (222), the first groove transition region (224), the groove bottom (221), the second groove transition region (225), and the second groove wall (223) are connected to form a U-shaped structure.

3. The turbine guide blade stress relief structure according to claim 2, characterized in that: The distance between the groove bottom (221) and the end surface of the exhaust edge (21) is the height of the U-shaped groove, the height of the U-shaped groove is H, and H is 1.5 to 5 mm; and / or The first notch transition area (224) and the second notch transition area (225) are both arcs, the radius of the first notch transition area (224) is R1, the radius of the second notch transition area (225) is R2, R1=R2=(0.3-0.6)H; and / or The distance between the first groove wall (222) and the second groove wall (223) is the U-shaped groove width, the U-shaped groove width is W, and the distance between two adjacent U-shaped groove structures (22) is L, W≤0.7L; The thickness of the U-shaped groove structure (22) is t, and t is 0.8 mm to 1.5 mm.

4. The turbine guide blade stress relief structure according to claim 1, characterized in that: The upper notch edge of the U-shaped groove and the lower notch edge of the U-shaped groove structure (22) are both rounded and transitioned, and the rounding radius is 0.2mm to 0.5mm.

5. The turbine guide blade stress relief structure according to any one of claims 1 to 4, characterized in that: The U-shaped groove upper groove edge and the U-shaped groove lower groove edge of the U-shaped groove structure (22) adopt a composite line design, including an elliptical transition section, a parabolic transition section or a combination of the two.

6. The turbine guide blade stress relief structure according to claim 5, characterized in that: The elliptical transition section satisfies the mathematical expression: a 2 x 2 +b 2 y 2 =1, where a is the major axis of the ellipse, b is the minor axis of the ellipse, x is the horizontal coordinate variable, y is the vertical coordinate variable, a=0.8~1.5mm, b=0.3~0.6mm; The parabolic transition section satisfies the mathematical expression: y=kx 2 , where x is the horizontal coordinate variable, y is the vertical coordinate variable, and k is the curvature coefficient, k = 0.05~0.

15.

7. The turbine guide blade stress relief structure according to claim 1, characterized in that: The inner surface of the U-shaped groove structure (22) is alternately arranged with arrayed micro-bumps and arrayed micro-pits; the arrayed micro-bumps include a plurality of spaced micro-bumps (5), and the micro-bumps (5) are suitable for inducing local micro-eddies, dispersing macroscopic stress fields, and reducing the main stress peak of the groove body; the arrayed micro-pits include a plurality of spaced micro-pits (6), and the micro-pits (6) are suitable for absorbing local stress peaks through plastic deformation.

8. A method for preparing a turbine guide blade stress relief structure, characterized in that: The method is a method for preparing the turbine guide blade stress relief structure according to any one of claims 1 to 7, comprising the following steps: S1. Split precision casting: Dividing the turbine blade body (1) and the upper edge plate (2) into a base module and a U-shaped groove module; S2. Module integration: Connecting the base module to the U-shaped slot module by diffusion welding; S3. Composite post-processing strengthening process: Laser shock peening is performed on the U-shaped groove structure (22) to induce a surface residual compressive stress layer; Electrolytically polishing the inner surface of the U-shaped groove structure (22); The U-shaped groove structure (22) is subjected to a microparticle shot peening treatment.

9. The method for preparing a turbine guide blade stress relief structure according to claim 8, characterized in that: The base module is prepared by directional solidification casting technology; and / or The U-shaped groove module is prepared by 3D printing ceramic core + directional solidification technology, and the negative mold structure of micro-convex platforms and micro-pits is etched on the surface of the ceramic core.

10. The method for preparing a turbine guide blade stress relief structure according to claim 9, characterized in that: The pouring temperature of the directional solidification casting is controlled above the alloy solidus, and a gradient cooling strategy is adopted in the cooling process to ensure that the U-shaped groove structure area solidifies first.

Images