High-pressure turbine guide vane suction surface echelon cooling structure and design method thereof

Abstract

The invention discloses a high-pressure turbine guide vane suction surface echelon cooling structure and a design method thereof, and belongs to the technical field of aero-engine turbine blade cooling. According to the structure, a suction surface is divided into a gill area, a midstream area and a downstream area in the flow direction and divided into a blade middle area, an upper near-end area and a lower near-end area in the spanwise direction, and according to the pressure gradient, the thermal load and the secondary flow intensity of all the areas, differential air film hole row layouts such as uniform cooling, hole diameter echelon in the flow direction and hole diameter echelon in the spanwise direction are adopted, so that cooling intensity is distributed according to needs. According to the design method, the wall surface temperature, the heat flow density and the secondary flow field are obtained through CFD or a test, regional thermal load and secondary flow intensity indexes are constructed, accordingly, the number of film hole rows, the aperture gradient and hole axis inclination and deflection parameters of each region are determined, and iterative optimization is conducted under the constraint of the total cooling air flow and pressure drop. The air film coverage effectiveness and the cold air utilization rate of a high-heat load area can be remarkably improved, and the service reliability and the service life of the high-pressure turbine guide vane are improved.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine turbine blade cooling technology, and relates to the optimized design of the air film cooling structure on the surface of high-pressure turbine guide vanes. Specifically, it relates to a novel stepped cooling structure for the suction surface of high-pressure turbine guide vanes and its design method, which is used to improve the cooling efficiency and temperature field uniformity of the guide vane suction surface under high temperature and high load conditions, and ensure the service safety and life of the blade. Background Technology

[0002] Film cooling (FSR) is a key cooling method commonly used on the outer surface of high-pressure turbine guide vanes in aero-engines, especially in the suction region. This technology involves arranging several inclined film cooling holes on the blade surface to inject cryogenic cooling gas from the compressor into the high-temperature mainstream boundary layer on the outer surface of the turbine guide vane. This forms a layer of cold gas near the wall, effectively reducing the direct exposure of the blade surface to the high-temperature combustion gases. In engineering applications, to balance design simplification and manufacturing convenience, existing turbine blade FSRs often employ a uniform arrangement, neglecting the temperature distribution in different regions and the entrainment and blow-off effects of vortex structures on the outflow. With the continuous increase in turbine inlet temperature, this uniform arrangement is highly susceptible to localized cooling failure, leading to overheating and subsequent thermal ablation, severely impacting engine operational safety.

[0003] The flow characteristics of the suction surface of aero-engine high-pressure turbine guide vanes are as follows: It exhibits a contracting flow pattern in the flow direction and a symmetrical distribution along the blade midline in the spanwise direction. Simultaneously, typical secondary flows such as horseshoe vortices and channel vortices exist in the channels near the suction surface. Under the influence of this complex vortex structure, the film gas deviates from its original streamline direction, resulting in varying degrees of uncovered areas on the blade surface. Furthermore, in the gill region where curvature changes drastically, the flow undergoes a gradient change from compressive to anticompression, making the film gas highly susceptible to detachment from the wall, inducing high-temperature failure. In the proximal region near the blade root or tip wall, horseshoe vortices and channel vortices strongly couple with the secondary flow on the endwall, producing a significant three-dimensional entrainment effect. Under traditional uniform perforation conditions, the film gas flow is often entrained towards the channel center or shifted along the spanwise direction, leading to severe insufficient cooling in the end region and downstream areas, and a significantly increased gradient between the peak blade surface temperature and the regional average temperature. It is evident that under the influence of complex flow, the existing uniformly arranged film cooling method cannot achieve a uniform film cooling effect. There are many areas where the film is not covered, and the temperature distribution varies greatly, resulting in a significant increase in temperature gradient. This no longer meets the requirements for thermal protection and safe and stable operation of turbine blades under high heat load.

[0004] In summary, under the complex three-dimensional flow and non-uniform thermal load conditions of high-pressure turbine guide vane suction surfaces, existing film cooling design methods, mainly based on uniform perforation and empirical local corrections, struggle to simultaneously achieve overall temperature field uniformity, local hotspot suppression, and cooling gas utilization efficiency. Therefore, developing a novel film cooling structure and its design method that can adapt to complex flow environments and specifically enhance cooling performance is a pressing technical problem in the field of aero-engine turbine blade cooling technology. Summary of the Invention

[0005] (a) Purpose of the invention The purpose of this invention is to propose a tiered cooling structure and design method for the suction surface of a high-pressure turbine guide vane. Based on the geometric characteristics of the high-pressure turbine guide vane and the characteristics of secondary flow in the channel, different forms of film cooling structures are designed for the gill region, mid-blade region, and near-end region of the suction surface to meet the cooling requirements of different areas. Its essential feature is the tiered arrangement of the film cooling holes, specifically: in the mid-blade region, a uniform cooling arrangement is used; in the gill region, a small hole arrangement is used upstream and a large hole arrangement is used downstream; in the complex near-end region, a tiered cooling method is used, with the hole diameter distributed tiered along the spanwise direction, i.e., large holes are used near the end region, and the hole diameter is appropriately reduced towards the mid-blade direction, so that the film cooling outflow can effectively resist the entrainment of secondary flow; in the near-downstream region, a concentrated tiered cooling method is used, with the hole diameter distributed tiered along the spanwise direction, i.e., large holes are used near the end region, and the hole diameter is appropriately reduced towards the mid-blade direction. Overall, by adjusting the air film cooling arrangement according to needs, the cold air can be rationally and effectively distributed to achieve the most ideal cooling effect, which has the advantages of strong functionality and clear purpose.

[0006] (II) Technical Solution To achieve the objective of this invention and solve its technical problems, the present invention adopts the following technical solution: The first objective of this invention is to provide a tiered cooling structure for the suction surface of a high-pressure turbine guide vane, used to implement differentiated film cooling on the suction surface of the high-pressure turbine guide vane to improve the effectiveness of film coverage, improve the temperature field of the suction surface and the utilization efficiency of cooling gas, specifically: The turbine guide vane suction surface is divided into gill region, midstream region and downstream region along the flow direction from the leading edge to the trailing edge. The midstream region is divided into two proximal regions near the upper and lower end walls and the blade mid-region between the two proximal regions in the spanwise direction. The downstream region is divided into two proximal regions in the spanwise direction. Each region is provided with air film perforations with different layout forms and connected to the cooling air chamber inside the guide vane. The gill region has at least two sets of air film pore rows arranged in the flow direction. The air film pores in each air film pore row are arranged from the leaf root to the leaf tip in the spread direction. The pore diameter of the air film pores in each air film pore row increases in sequence along the flow direction, forming a tiered cooling layout that enhances the formation and adhesion of air film in the vicinity of the leading edge. In the midstream region, at least two sets of film cooling pores are arranged in the flow direction. The pore diameter and spacing of each film cooling pore are basically the same, forming a uniform reference film cooling in the midstream region. In the two near-end regions of the midstream region, at least two sets of film cooling pores are respectively arranged in the flow direction. In each film cooling pore row, the pore diameter of the film cooling pores near the end wall is larger than that of the pores near the midstream region. The pore diameter of the film cooling pores gradually increases from the midstream region to the end wall, forming a stepped cooling layout along the span. The downstream region has at least two sets of air film pores in the flow direction, forming a local lattice arrangement in each proximal region along the span, and the pore diameter of the air film pores gradually decreases from the end wall to the middle region of the blade, forming a locally concentrated and stepped cooling layout along the span. By partitioning the air film pores on the suction surface, a tiered air film cooling structure is formed, which features tiered pore diameters along the flow direction in the gill area, uniform cooling in the middle area of ​​the mid-stream leaf, and tiered and locally enhanced cooling along the spread direction in the mid-stream and downstream proximal areas.

[0007] The second objective of this invention is to provide a design method for the above-mentioned high-pressure turbine guide vane suction surface cascade cooling structure, which includes at least the following steps: S100. Obtaining Operating Conditions and Flow Field Characteristics: Based on the structural parameters of the target high-pressure turbine stage and representative design operating conditions, CFD numerical calculations or experimental tests are used to obtain information on the wall temperature distribution, local heat flux density distribution, static pressure distribution, and secondary flow intensity distribution in the end region on the suction surface of the guide vane. S200. Region Division and Characteristic Index Construction: Based on the static pressure gradient, heat flux density and / or secondary flow intensity distribution on the guide vane suction surface, the suction surface is divided into gill region, midstream region and downstream region along the flow direction. The midstream region is further divided into two proximal regions and mid-leaf region in the spanwise direction, and the downstream region is divided into two proximal regions in the spanwise direction. At the same time, the heat load and secondary flow intensity index of each region are calculated. S300. Suction surface tiered cooling parameter allocation: Based on the heat load and secondary flow intensity index of each region, determine the relationship between the number of air film pore rows arranged along the flow direction in the gill zone and the pore diameter increasing from small to large, the number of air film pore rows arranged along the flow direction in the midstream leaf mid-section and the pore diameter and pore spacing parameters, as well as the relationship between the pore diameter of the air film pores gradually increasing from the leaf mid-section to the end wall in the proximal section of the midstream zone and the relationship between the pore diameter of the air film pores gradually decreasing from the end wall to the leaf mid-section in the proximal section of the downstream zone and the relationship between the pore diameter of the air film pores gradually decreasing from the end wall to the leaf mid-section and the local lattice arrangement. S400. Constraint Evaluation and Iterative Optimization: Under the constraints of total cooling gas volume and allowable pressure drop, evaluate the cooling performance and flow loss of the film cooling hole arrangement scheme, and perform iterative optimization until the evaluation results meet the predetermined performance indicators.

[0008] (III) Technical Effects Compared with the prior art, the high-pressure turbine guide vane suction surface tiered cooling structure and its design method of the present invention have the following beneficial and significant technical effects: (1) This invention divides the suction surface into gill, midstream and downstream regions along the flow direction, and further subdivides it into leaf mid and near-end regions in the spanwise direction. Differentiated air film pore arrangement and pore size gradient are implemented for different regions based on pressure gradient, heat load level and secondary flow intensity. Compared with the traditional uniform pore arrangement scheme, it can significantly improve the air film coverage and adhesion stability in high heat load areas under limited cooling air volume, suppress air film peeling phenomenon under the action of secondary flow in the gill reverse pressure section and end region, make the overall temperature field of the guide vane suction surface more uniform, and significantly reduce local hot spots.

[0009] (2) This invention introduces wall temperature, heat flux density, and secondary flow intensity field obtained through CFD numerical calculations or experimental tests using a design method to construct regional heat load and secondary flow intensity indices. Based on these indices, the number of film cooling holes, aperture gradient, and local lattice layout in each region are determined. Under the constraints of total cooling gas volume and pressure drop, the cooling performance and flow loss are iteratively evaluated and optimized, thus forming a closed-loop design system of flow field-indices-geometric parameters. This method enables quantifiable and adjustable design of tiered cooling layouts, resulting in structures with good cooling margins and robustness under various operating conditions.

[0010] (3) In terms of structural implementation, this invention adopts a cylindrical film cooling hole arrangement. By limiting and constraining the range of parameters such as hole diameter, number of hole rows, hole spacing, and tilt angle, the tiered cooling structure can be quickly transplanted and calibrated on high-pressure turbine guide vanes of different sizes and profiles, exhibiting good process compatibility and engineering feasibility. Under the premise of ensuring controllable overall efficiency loss, it significantly reduces the maximum wall temperature of the guide vane suction surface and the temperature gradient along the flow direction and span, improving the high-temperature service reliability and life reserve of the blades, and providing effective cooling technology support for further increasing the turbine inlet temperature. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 The diagram shows a stepped film cooling layout for the suction surface of the turbine guide vane. Figure 2 The image shown is a top view of the uniform cooling layout in the leaf mid-section of the midstream region; Figure 3 The image shown is a top view of the cooling layout of the small pores upstream and the large pores downstream of the gill area. Figure 4 The diagram shown is a cross-sectional view of the tiered cooling layout in the proximal section of the midstream region. Figure 5 The diagram shows a cross-sectional view of the concentrated tiered cooling layout in the near-end area of ​​the downstream zone. Figure 6 The image shown is a partial cross-sectional view of the tiered cooling layout. Figure 7 The image shown is a partial top view of the tiered cooling layout; Figure 8 The diagram shown is a flowchart of the structural design method for the tiered cooling system of the turbine guide vane suction surface.

[0013] Explanation of reference numerals in the attached diagram: 1-tail margin, 2-gill region, 3-mid-leaf region of the midstream zone, 4-proximal region of the midstream zone, 5-proximal region of the downstream zone, 6-air film pore, 7-air film pore inlet, 8-air film pore outlet, 9-main stream, 10-jet, 11-flow direction, 12-spreading direction. Detailed Implementation

[0014] This invention aims to provide a tiered cooling structure for the suction surface of a high-pressure turbine guide vane and its design method. To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. The described embodiments are some, but not all, embodiments of this invention, and are exemplary and intended to explain the invention, not to limit it. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0015] Example 1: Cascaded Cooling Structure for Suction Surface of High-Pressure Turbine Guide Blades As a specific example, Figure 1 The diagram shows a film cooling layout structure obtained according to the high-pressure turbine blade suction surface tiered cooling design method provided in an embodiment of the present invention. It can be seen that, compared with the conventional film cooling system characterized by uniform perforation along the spanwise direction from blade root to blade tip, the film cooling layout structure provided in this embodiment of the present invention adopts a uniform perforation cooling layout in the mid-blade region, a small perforation upstream and a large perforation downstream cooling layout along the flow direction in the gill region, a tiered perforation layout in the proximal region, and a concentrated tiered perforation layout in the proximal downstream region. Specifically: In this embodiment of the invention, the suction surface of the turbine guide vane is divided into a gill region 2, a midstream region, and a downstream region along the flow direction from the leading edge to the trailing edge. The midstream region is further divided in the spanwise direction into two proximal regions 4 near the upper and lower end walls and a mid-blade region 3 located between the two proximal regions. The downstream region is divided in the spanwise direction into two proximal regions 5. Each region is provided with air film perforations of different layouts and connected to the cooling air chamber inside the guide vane. The gill region 2 has at least two sets of air film perforations arranged in the flow direction. The air film perforations 6 in each air film perforation are arranged from the blade root to the blade tip in the spanwise direction. The diameter of the air film perforations in each air film perforation increases in a stepwise manner along the flow direction, forming a stepwise cooling layout that enhances the formation and adhesion of air film in the vicinity of the leading edge. The mid-blade region 3 in the midstream region has at least two sets of air film perforations arranged in the flow direction. The diameter and spacing of the perforations in each air film perforation are basically the same. 3. A uniform reference air film cooling is formed; in the two proximal regions 4 of the midstream region, at least two sets of air film pore rows are respectively arranged in the flow direction. In each air film pore row, the diameter of the air film pores near the end wall is larger than that near the leaf mid region 3. The diameter of the air film pores increases stepwise from the leaf mid region 3 towards the end wall, forming a stepped cooling layout along the span; in the two proximal regions 5 of the downstream region, at least two sets of air film pore rows are respectively arranged in the flow direction. A local lattice arrangement is formed in each proximal region 5 along the span, and the diameter of the air film pores decreases stepwise from the end wall towards the leaf mid region, forming a locally concentrated and stepped cooling layout along the span; the present invention forms a stepped air film cooling structure by dividing the air film pores on the suction surface into sections, with stepped pore diameters along the flow direction in the gill region, uniform cooling in the midstream leaf mid region, and stepped and locally enhanced cooling along the span in the midstream and downstream proximal regions.

[0016] Figure 6 The image shown is a partial cross-sectional view of the tiered film cooling layout. x - z (Cross-section). In this embodiment of the invention, the film gas holes in each region of the suction surface are through holes inclined relative to the outer contour of the suction surface. Each film gas hole includes an air inlet communicating with the internal cooling air chamber of the guide vane and an air outlet opened on the outer surface of the suction surface. The opening of the air outlet faces the mainstream flow direction of the high-temperature combustion gas along the tangent direction of the local suction surface contour, so that the cooling gas is sprayed out from the internal cooling air chamber and adheres and spreads along the outer contour of the suction surface to form a film gas. The angle between the center line of the film gas hole and the horizontal direction (i.e., the plane where the tangent of the corresponding suction surface contour is located) is . α , α The value ranges from 30° to 60°, and α The value of should be chosen to ensure the adhesion ability of the cooling jet to the wall and the effective film thickness, while avoiding excessive impact angle that could lead to gas film separation and increased boundary layer disturbance, thereby improving the effectiveness of gas film coverage and the utilization efficiency of cooling gas.

[0017] Figure 7 The image shown is a partial top view of the tiered film cooling layout. x - z(Cross section). In this embodiment of the invention, the axis of the air film pores in each region of the suction surface has a deflection angle relative to the mainstream flow direction in the blade spanwise direction. β , β It can be 0°, or it can be adjusted in the opposite direction according to the direction of the secondary flow. The adjustment range is between 0° and 65°, and it must be at least in the proximal region of the midstream and downstream regions. β The direction is set to be opposite to the direction of motion of the secondary flow dominant vortex at the corresponding position, so as to counteract the entrainment and lifting of the film jet by the strong secondary flow in the end region, making it easier for the film to reattach to the suction surface of the guide vane and expand along the spanwise direction.

[0018] In this embodiment of the invention, the pore shape of the air film pores in each region is designed differently according to the flow characteristics of the region. The air film pores in each group of air film pore rows in the gill region adopt cylindrical pores, diffuser pores, or composite angle pores. The air film pores in the mid-leaf zone and proximal zone of the midstream region adopt cylindrical pores or diffuser pores. The large-diameter air film pores in the proximal zone of the downstream region adopt diffuser pores or shaped cooling pores to enhance the air film diffusion effect. The diffusion angle of the diffuser pores is in the range of 8~15°, and the ratio of the outlet pore diameter to the inlet pore diameter is in the range of 1.2~2.0. By combining different pore shapes, a balance between air film coverage and cooling efficiency is achieved in each region.

[0019] Figure 2 The image shown is a top view of the uniform cooling layout in the midstream region of the leaf. y - z (Surface). In this embodiment of the invention, for the leaf mid-section in the midstream region, the air film pores are cylindrical with a diameter of [missing information]. D , D The diameter is between 0.5 and 1.0 mm. The air-film pores in the mid-leaf zone can be arranged in a single row or multiple rows, with 6 to 20 pores per row. The upstream and downstream pore rows can be arranged in a straight line or a staggered arrangement. The spacing between adjacent air-film pores in the same row is... P , P In 2 D ~4 D Between. The spacing between adjacent air film pore rows is Q , Q In 10 D ~20 D Between these layers, a basically uniform and continuous reference film cooling layer is obtained, providing basic temperature control for the midstream section of the entire suction surface, while also providing a reference for the tiered cooling of the near-end region.

[0020] Figure 3 The image shown is a top view of the air film cooling layout of the upstream small pores and downstream large pores in the gill area. y - z (Surface). In this embodiment of the invention, the air film pores in the gill region have a cylindrical structure, with the pore diameter of the small pores upstream along the flow direction being 0.3~0.5 mm. DThe downstream large aperture is D The upstream holes are arranged in one row, with 10-30 air-film perforations; the downstream holes are arranged in one row, with 10-30 air-film perforations. The upstream and downstream perforation rows can be arranged in a straight line or a staggered arrangement. The spacing between adjacent air-film perforations in the same row is... P In 2~5 D Between. The spacing between adjacent upstream and downstream air film pore rows. Q In 2~5 D Between these, in the gill region, continuous film formation from small pores to large pores and downstream reinforcement cooling are achieved in the gradient change area of ​​forward and reverse pressure, preventing the high-temperature gas at the leading edge from scouring and thermally eroding the front section of the suction head.

[0021] Figure 4 The image shown is a top view of the tiered cooling layout in the near-end section of the midstream region. y - z (Surface). In this embodiment of the invention, the film pores in the proximal region of the midstream area are cylindrical structures with their diameters distributed in a stepped manner along the spanwise direction. Near the strong secondary flow location at the root, the film pore diameter is... D 1, D 1 is distributed in the range of 1.4~3 D Between; while near the mid-leaf region, the air film pore size is D 2, D 2< D 1, D 2. Distributed between 1 and 1.4 D Between them. The tiered cooling layout in the near-end region and the uniform cooling layout in the middle region are connected in rows along the span, and the number of holes in each row is the same. The number of tiered film cooling holes in each row is between 4 and 6, which provides a high-momentum film jet in the strong secondary flow region of the end wall and suppresses entrainment.

[0022] Figure 5 The image shown is a top view of the concentrated tiered cooling layout in the near-end area of ​​the downstream zone. y - z (Surface). In this embodiment of the invention, the film pores in the downstream proximal region are cylindrical, with their diameters distributed in a stepped manner along the spanwise direction. Near the strong secondary flow location at the root, the film pore diameter is... D 3, D 3> D 1, D 3. The distribution ranges from 1.6 to 3.2. D Between; while near the mid-leaf region, the air film pore size is D 4, D 4< D 3, D 4 is distributed between 1 and 1.6. D Between. The centralized tiered cooling layout is divided into two rows, upstream and downstream, with some areas arranged in a dot matrix pattern in the near downstream area. Each row has 4 to 6 units, forming a longitudinally enhanced film cooling layout in the local high heat load area of ​​the near downstream.

[0023] It should be noted that the tiered cooling structure provided in this embodiment 1 achieves precise distribution and dynamic optimization of cool air through zoned differentiated design. Specifically, uniform holes in the mid-blade zone ensure baseline cooling, while large and small holes in the gill zone adapt to flow acceleration and adverse pressure gradient changes. Tiered holes in the proximal zone effectively resist the entrainment effect of secondary flow, and concentrated tiered holes in the downstream proximal zone enhance the cooling coverage of local high heat load areas in a lattice pattern. This not only solves the problems of uncovered air film and increased temperature gradient caused by uniform arrangement, but also improves air film adhesion and coverage uniformity through the combination of simple cylindrical holes or irregular holes.

[0024] Example 2: Design Method for Suction Surface Cascade Cooling Structure Based on Embodiment 1 above, Embodiment 2 further elaborates on the design method of the high-pressure turbine guide vane suction surface cascade cooling structure, such as... Figure 8 As shown, its implementation mainly includes the following steps: S100. Obtaining operating conditions and flow field characteristics: Based on the structural parameters and representative design conditions of the target high-pressure turbine stage, CFD numerical calculations or experimental tests are used to obtain information on the wall temperature distribution, local heat flux density distribution, static pressure distribution, and end-region secondary flow intensity distribution on the guide vane suction surface. The representative design conditions include at least the rated design conditions. When using CFD numerical calculations, a three-dimensional steady or unsteady solution is performed on the guide vane passage. The computational domain covers the upstream and downstream flow field regions with a predetermined length before and after the guide vane. The boundary layer region near the suction surface is meshed, and it is necessary to ensure that the wall temperature distribution, local heat flux density distribution, and end-region secondary flow intensity distribution can be spatially continuous and accurately analyzed.

[0025] S200. Regional Division and Characteristic Indicator Construction: Based on the static pressure gradient, heat flux density, and / or secondary flow intensity distribution on the guide vane suction surface, the suction surface is divided into gill, midstream, and downstream regions along the flow direction. The midstream region is further divided into two proximal regions and a mid-blade region along the span, and the downstream region is divided into two proximal regions along the span. The heat load and secondary flow intensity indices for each region are calculated. The heat load index is obtained by area-weighted averaging of the wall heat flux density or wall temperature field in each region, combined with peak value normalization. The secondary flow intensity index is obtained by squared averaging or integration of the secondary flow velocity vector and / or vorticity in each region. Each index is compared with a preset threshold. This allows for the accurate identification of gill regions along the suction surface where the pressure gradient changes from favorable to unfavorable and the heat load increases significantly, and the accurate identification of proximal regions along the span where the secondary flow intensity near the endwall is significantly higher than that in the mid-blade region.

[0026] Preferably, the boundary between the gill region and the midstream region is defined as the inflection point of the pressure coefficient where the external flow field of the suction surface transitions from a strong acceleration zone to a constant velocity zone or a deceleration zone. This ensures that the small-aperture stepped air film in the gill region can cover the extremely thin boundary layer region before the laminar-turbulent transition. The boundary between the midstream region and the downstream region is defined as the location of the suction surface shock wave impact or the starting point of the adverse pressure gradient. This defines the region where the air film's anti-blow-off capability needs to be enhanced through stepped orifice expansion. The spanwise boundary between the near-end region and the middle blade region is defined as the stripping line trajectory of the end-wall channel vortex on the suction surface. This is determined by calculating the contour lines where the normal integral value of the near-wall flow vortex exceeds a preset threshold. This ensures that the stepped cooling structure in the near-end region acts on the core influence domain of the secondary flow.

[0027] S300. Suction surface tiered cooling parameter allocation: Based on the heat load and secondary flow intensity indices of each region, the following relationships were determined: the number of air film pores arranged along the flow direction in the gill zone and the relationship of the pore diameter increasing from small to large; the number of air film pores arranged along the flow direction in the midstream leaf zone and the arrangement parameters of the pore diameter and pore spacing; the relationship of the air film pore diameter gradually increasing from the leaf zone to the end wall in the proximal zone of the midstream zone; and the relationship of the air film pore diameter gradually decreasing from the end wall to the leaf zone in the proximal zone of the downstream zone and being arranged in a local lattice pattern.

[0028] As a preferred approach, when determining the number of air film pore rows and the pore size gradient in the gill zone, midstream zone, leaf midstream zone, and proximal zone of the midstream and downstream zones, a monotonic mapping relationship between the number of pore rows, pore size grade, and each index is established based on the distribution trend of heat load index and secondary flow intensity index of each region with the flow direction and span. This ensures that regions with higher heat load and / or secondary flow intensity index are allocated more air film pore rows, larger pore size gradient, or higher upper limit of pore size, while regions with lower heat load index use fewer pore rows and smaller pore sizes, so as to achieve on-demand allocation of cooling resources under the premise of limited total cooling air volume.

[0029] More preferably, when determining the arrangement parameters of the film gas holes in each region, the tilt angle α and / or spanwise deflection angle β of the film gas holes are also determined according to the secondary flow intensity index and the local mainstream flow direction of the corresponding region. When the secondary flow intensity index of a certain region exceeds a preset threshold, the spanwise deflection angle β of the film gas holes in that region is set to be opposite to the dominant migration direction of the secondary flow, and the tilt angle α is reduced within the allowable range to enhance the adhesion ability of the cooling jet on the suction surface and the reverse secondary flow expansion ability.

[0030] S400. Constraint Evaluation and Iterative Optimization: Under the constraints of total cooling gas volume and allowable pressure drop, the cooling performance and flow loss of the film cooling pore arrangement scheme are evaluated, and iterative optimization is performed until the evaluation results meet the predetermined performance indicators. The evaluation of the cooling performance and flow loss of the film cooling pore arrangement scheme includes: performing CFD numerical calculations on the film cooling pore arrangement scheme to obtain the maximum wall temperature of the suction surface, the wall temperature gradient along the flow direction and spanwise direction, the cooling gas mass flow rate, and / or the total pressure loss indicators. The calculation results are compared with the preset performance targets. When the maximum wall temperature or temperature gradient exceeds the allowable value and / or the total pressure loss exceeds the allowable value, the diameter, number of pore rows, and arrangement range of the film cooling pores in the gill and proximal regions are first adjusted according to the preset iteration rules, and the pore row parameters in the mid-leaf region are simultaneously fine-tuned until all evaluation indicators meet the predetermined performance requirements.

[0031] It should be noted that this embodiment 2 presents a design method based on CFD numerical calculations or experimental data for the tiered cooling structure of the high-pressure turbine guide vane suction surface. Through obtaining operating conditions and flow field characteristics, dividing the region and constructing characteristic indicators, allocating tiered cooling parameters, and iterative evaluation and optimization under constraints of total cooling gas volume and allowable pressure drop, a quantitative mapping mechanism between cooling geometric parameters and local thermal load and secondary flow intensity is established. This design method not only ensures the scientific rigor and accuracy of the tiered cooling structure design but also optimizes cooling efficiency under limited cooling gas volume constraints through multi-physics coupling iteration, providing a systematic solution for the refined design of high-performance turbine blades.

[0032] The objectives of this invention have been fully and effectively achieved through the above embodiments. Those skilled in the art will understand that this invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments described above. Although the invention has been described with reference to what is currently considered the most practical and preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments, and any modifications that do not depart from the functional and structural principles of the invention will be included within the scope of the claims.

Claims

1. A tiered cooling structure for the suction surface of a high-pressure turbine guide vane, characterized in that, The turbine guide vane suction surface is divided into a gill region, a midstream region, and a downstream region along the flow direction from the leading edge to the trailing edge. The midstream region is further divided in the spanwise direction into two proximal regions near the upper and lower end walls and a mid-blade region located between the two proximal regions. The downstream region is also divided in the spanwise direction into two proximal regions. Each region has a different layout of film-forming perforations that communicate with the internal cooling air chamber of the guide vane; and wherein: The gill region has at least two sets of air film pore rows arranged in the flow direction. The air film pores in each air film pore row are arranged from the leaf root to the leaf tip in the spread direction. The pore diameter of the air film pores in each air film pore row increases in sequence along the flow direction, forming a tiered cooling layout that enhances the formation and adhesion of air film in the vicinity of the leading edge. In the midstream region, at least two sets of film cooling pores are arranged in the flow direction. The pore diameter and spacing of each film cooling pore are basically the same, forming a uniform reference film cooling in the midstream region. In the two near-end regions of the midstream region, at least two sets of film cooling pores are respectively arranged in the flow direction. In each film cooling pore row, the pore diameter of the film cooling pores near the end wall is larger than that of the pores near the midstream region. The pore diameter of the film cooling pores gradually increases from the midstream region to the end wall, forming a stepped cooling layout along the span. The two proximal regions of the downstream region are each provided with at least two sets of film cooling pores in the flow direction, forming a local lattice arrangement in each proximal region along the span, and the diameter of the film cooling pores gradually decreases from the end wall to the middle region of the blade, forming a locally concentrated and stepped cooling layout along the span.

2. The high-pressure turbine guide vane suction surface tiered cooling structure according to claim 1, characterized in that, The film cooling vents in each region of the suction surface are all through holes inclined relative to the outer contour of the suction surface. Each film cooling vent includes an inlet communicating with the internal cooling air chamber of the guide vane and an outlet on the outer surface of the suction surface. The outlet faces the main flow direction of the high-temperature combustion gas along the tangent of the local suction surface contour, so that the cooling gas ejected from the internal cooling air chamber adheres and spreads along the suction surface contour to form a film cooling gas. The angle between the axis of each film cooling vent and the plane containing the tangent of the suction surface contour at the corresponding position is defined as the inclination angle. α , α The value range is 30° to 60°, and α The value of ...

3. The high-pressure turbine guide vane suction surface tiered cooling structure according to claim 2, characterized in that, The pore axes of the film gas pores in each region of the suction surface are deflected relative to the mainstream flow direction along the blade span. β Its value ranges from 0° to 65°, and is at least within the proximal regions of the midstream and downstream regions. β The direction is set to be opposite to the direction of motion of the secondary flow-dominant vortex at the corresponding position.

4. The high-pressure turbine guide vane suction surface tiered cooling structure according to claim 1, characterized in that, Within the leaf mid-section of the midstream region, each air-film pore is a cylindrical structure, and its pore size is defined as follows: D , D Within the range of 0.5~1.0 mm, the air film pores are arranged in single or multiple rows along the flow direction, with each row containing 6~20 air film pores, and the spacing between adjacent air film pores in the same row is... P 2~4 D The spacing between adjacent air film pore rows Q 10~20 D Furthermore, the upstream and downstream holes are arranged in a straight or staggered pattern in the span direction.

5. The high-pressure turbine guide vane suction surface tiered cooling structure according to claim 4, characterized in that, In the gill region, the air film pores in each row of air film pores are all cylindrical structures, with the upstream air film pore row employing a small pore arrangement, with a pore diameter of 0.3~0.5 mm. D The downstream air film perforation array adopts a large-pore arrangement with a pore diameter of [missing information]. D Furthermore, the number of air film pores in each row is one row in both the upstream and downstream of the gill area, with each row containing 10 to 30 air film pores, and the spacing between adjacent air film pores in the same row is... P 2~5 D The spacing between adjacent upstream and downstream air film pore rows Q 2~5 D Furthermore, the upstream and downstream air film pores are arranged in a straight or staggered pattern in the longitudinal direction.

6. The high-pressure turbine guide vane suction surface cascade cooling structure according to claim 4, characterized in that, Within the two proximal regions of the midstream area, each air-film pore is a cylindrical structure, with its pore size distributed in a stepped manner along the longitudinal direction. The pore size of the air-film pores near the leaf root or leaf tip wall is [missing information]. D 1, D 1 is 1.4~3 D The pore size of the air film pores on the side closest to the mid-leaf region is D 2, and D 2< D 1, D 2 represents 1~1.4 D Furthermore, the tiered cooling layout of the two proximal regions is connected one-to-one with each air film vent array in the mid-section of the blade in the spanwise direction, ensuring that the number of vent arrays in the proximal region and the mid-section of the blade remains consistent, with 4 to 6 tiered air film vent arrays per row.

7. The high-pressure turbine guide vane suction surface cascade cooling structure according to claim 6, characterized in that, In the two proximal regions of the downstream area, the film pores are all cylindrical structures, with their pore diameters distributed in a stepped manner along the longitudinal direction. The pore diameter of the film pores near the end wall is [missing information]. D 3, and D 3> D 1, D 3 represents 1.6~3.

2. D The pore size of the air film pores on the side closest to the mid-leaf region is D 4, and D 4< D 3, D 4 represents 1~1.6 D Furthermore, the film pores in the downstream two proximal regions are arranged in two rows along the flow direction, with each row containing 4 to 6 film pores. The two rows of film pores form a local lattice distribution along the longitudinal direction in each proximal region.

8. The high-pressure turbine guide vane suction surface cascade cooling structure according to claim 1, characterized in that, The pore shape of the air film pores in each region is designed differently according to the flow characteristics of the region. The air film pores in each group of air film pore rows in the gill zone adopt one or more combinations of cylindrical pores, diffuser pores, or composite angle pores. The air film pores in the mid-leaf zone and proximal zone of the midstream zone adopt cylindrical pores or diffuser pores. The large-diameter air film pores in the proximal zone of the downstream zone adopt diffuser pores or forming cooling pores. The diffusion angle of the diffuser pores is in the range of 8~15°, and the ratio of the outlet pore diameter to the inlet pore diameter is in the range of 1.2~2.

0.

9. A design method for a high-pressure turbine guide vane suction surface cascade cooling structure according to any one of claims 1 to 8, characterized in that, It should include at least the following steps: S100. Based on the structural parameters and representative design conditions of the target high-pressure turbine stage, CFD numerical calculations or experimental tests are used to obtain information on the wall temperature distribution, local heat flux density distribution, static pressure distribution, and secondary flow intensity distribution in the end region on the suction surface of the guide vane. S200. Based on the static pressure gradient, heat flux density and / or secondary flow intensity distribution on the guide vane suction surface, the suction surface is divided into gill region, midstream region and downstream region along the flow direction. The midstream region is further divided into two proximal regions and mid-leaf region in the spanwise direction, and the downstream region is divided into two proximal regions in the spanwise direction. At the same time, the heat load and secondary flow intensity index of each region are calculated. S300. Based on the heat load and secondary flow intensity indices of each region, determine the relationship between the number of air film pores arranged along the flow direction in the gill zone and the gradual increase in pore diameter from small to large; the relationship between the number of air film pores arranged along the flow direction in the midstream leaf mid-section and the arrangement parameters of pore diameter and pore spacing; the relationship between the gradual increase in pore diameter of air film pores from the leaf mid-section towards the end wall in the proximal region of the midstream zone and the relationship between the gradual decrease in pore diameter of air film pores from the end wall towards the leaf mid-section in the proximal region of the downstream zone and the relationship of local lattice arrangement. S400. Under the constraints of total cooling gas volume and allowable pressure drop, evaluate the cooling performance and flow loss of the film cooling hole arrangement scheme, and perform iterative optimization until the evaluation results meet the predetermined performance indicators.

10. The method according to claim 9, characterized in that, In step S100, the representative design conditions include at least the rated design conditions. When using CFD numerical calculation, the guide vane channel is solved in three dimensions as steady or unsteady. The calculation domain covers the upstream and downstream flow field regions with a preset length before and after the guide vane. The boundary layer region near the suction surface is meshed. It is necessary to ensure that the wall temperature distribution, local heat flux density distribution and end region secondary flow intensity distribution can be analyzed continuously and accurately in space.

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