A C-type film hole cooling structure for hot end components of gas turbines

Abstract

The present invention relates to the field of heat transfer and cooling technology for hot-end components of gas turbines, and in particular to a C-shaped film hole cooling structure for hot-end components of gas turbines, comprising a plurality of film holes formed on a solid wall of the hot end, the film holes being formed obliquely, the film holes comprising a cylindrical section, one end of the cylindrical section being connected to an expansion section, an end of the cylindrical section remote from the expansion section being provided with a cold air inlet, an end of the expansion section remote from the cylindrical section being provided with an outlet profile, the outlet profile being a C-shaped cold air outlet, an end of the expansion section facing the cylindrical section being provided with an inlet profile, the outlet profile and the inlet profile being connected by a ruled surface to form a C-shaped expansion section. The film hole of the present invention can effectively inherit the advantages of bifurcated holes and convergent slit-shaped holes, can form an ideal anti-kidney vortex structure, promote the lateral expansion of cold air, increase the coverage area of ​​the film in the direction of the film, enhance the wall attachment effect of the film, thereby improving the film cooling efficiency, and at the same time can inhibit flow separation in the hole and reduce flow loss.

Description

Technical Field

[0001] The present invention relates to the technical field of heat transfer and cooling of hot end components of a gas turbine, and in particular to a C-shaped air film hole cooling structure applied to the hot end components of a gas turbine. Background Art

[0002] Gas turbine engines, a thermal power device based on the Brayton cycle, are widely used in modern military and industrial applications due to their powerful output and high thermal efficiency. Gas turbine engines operate in an extremely harsh and demanding environment characterized by high temperature, high pressure, and high speed. The high temperature environment is particularly evident in the turbine, one of its three core components. Experience shows that, assuming the engine size remains constant, a 56K increase in turbine inlet temperature can increase gas turbine thrust by 8-13% and improve cycle efficiency by 2-4%. The turbine inlet temperature of today's advanced aircraft engines exceeds 2000K, but the temperature resistance limit of turbine blade materials is far lower than the turbine inlet temperature, necessitating the use of efficient cooling technology to ensure proper operation.

[0003] Film cooling, one of the most widely used and efficient cooling technologies, initially employed cylindrical holes. In-depth research by domestic and international scholars has revealed that within the flow field structure formed by the cold air jet from a cylindrical hole, counter-rotating kidney-shaped vortex pairs possess the highest intensity relative to other vortex systems. Kidney vortices draw the mainstream air beneath the cold air, enhancing mixing and lifting the cold air off the wall, significantly detrimental to film cooling. Based on this, researchers have designed outlet-expanding, shaped holes, exemplified by dustpan holes. These holes increase the outlet area and width of the film holes by expanding in the flow or span direction, thereby reducing the momentum of the cold air jet, increasing the span-wise coverage of the film, and increasing the spacing between the kidney-shaped vortex pairs to reduce induced lift and induce the formation of anti-kidney vortices. However, the classic outlet-expanding, shaped hole has significant shortcomings in terms of flow field structure. The kidney-shaped vortex pairs still dominate the flow field, preventing the active formation of anti-kidney vortex structures conducive to film cooling.

[0004] To improve the coverage and cooling efficiency of film cooling, researchers have made numerous improvements to discrete film hole structures. Bifurcated holes are one of the most promising areas for improvement. Combining two or more cylindrical holes into a single film hole unit increases the film coverage. Meanwhile, the multiple jets of cold air from the bifurcated holes can induce the formation of an anti-kidney vortex structure that is beneficial for film cooling. For example, the tree-branched film hole structure disclosed in Chinese patent application CN201710454453.5, the branched film hole structure disclosed in Chinese patent application CN201711202938.1, the cross-type X film hole structure disclosed in Chinese patent application CN201910006511.7, and the cross-type Y film hole structure disclosed in Chinese patent application CN201910007232.2 all belong to the bifurcated hole type. However, bifurcated holes are sensitive to the spacing between holes. When the spacing between bifurcated holes is large, the multiple cold air jets will be relatively independent and unable to form the ideal anti-kidney vortex structure. Small spacing between holes requires high processing and manufacturing requirements, and is also detrimental to the structural strength of the turbine blade. The cat ear holes proposed by Japanese scholars, as well as the discrete air film holes disclosed in Chinese patent application CN201310236780.5 and the crescent-shaped air film holes disclosed in Chinese patent application 202210520834.X, can effectively solve the above problems of bifurcated holes. That is, the various branches of the bifurcated hole are contained in a certain way to form a whole, thereby improving the air film hole into a special-shaped hole structure consisting of a cylindrical segment and a bifurcated containing segment.

[0005] While this technical solution can actively form anti-kidney vortices that are beneficial for film cooling, the vortex structure of a single film hole unit typically consists of two pairs of adjacent kidney vortices, making it difficult to form a vortex structure dominated by anti-kidney vortices, which is detrimental to the spanwise extension of the cooling air. Furthermore, when the film holes have a large outlet width, the large expansion angle makes it prone to severe flow separation within the hole, exacerbating the mixing of cooling air with the mainstream and increasing flow losses, which is detrimental to the cooling effect. Summary of the Invention

[0006] The object of the present invention is to provide a C-type film hole cooling structure applied to the hot end component of a gas turbine, so as to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above-mentioned object, the present invention provides the following solution: a C-shaped film hole cooling structure applied to a hot end component of a gas turbine, comprising a plurality of film holes formed on a solid wall of the hot end, the film holes being formed obliquely, the film holes comprising a cylindrical section, one end of the cylindrical section being connected to an expansion section, an end of the cylindrical section remote from the expansion section being provided with a cold air inlet, an end of the expansion section remote from the cylindrical section being provided with an outlet profile, the outlet profile being a C-shaped cold air outlet, an end of the expansion section facing the cylindrical section being provided with an inlet profile, the outlet profile being connected to the inlet profile by a ruled surface to form the C-shaped expansion section;

[0008] The method for constructing the outlet profile is as follows: the intersection O1 is obtained by intersecting the axis of the air film hole with the tangent plane of the outer surface of the hot end solid wall, and the intersection O1 is obtained by intersecting the axis of the air film hole with the tangent plane of the outer surface of the hot end solid wall. 12 Mark point O2 at the center, and take point O2 as the midpoint to draw two concentric ellipses with their semi-major axes a1 and a2 and their semi-minor axes b1 and b2 respectively. Draw a large ellipse through a1 and b1, and a small ellipse through a2 and b2. Take straight lines O1 and O2 as axes of symmetry and draw two flow direction auxiliary lines with a spacing of W, where W is the transverse outlet width of the air film hole. The large ellipse is rounded with the two auxiliary lines, with a rounding radius of R6, to form a C-shaped upstream elliptical segment and a C-shaped upstream rounded segment. The small ellipse is rounded with the two auxiliary lines, with a rounding radius of R7, to form a C-shaped downstream rounded segment and a C-shaped downstream elliptical segment. The outlet profile is C-shaped.

[0009] Preferably, the diameter D of the cylindrical segment is in the range of 0.4 mm ≤ D ≤ 1.0 mm.

[0010] Preferably, the ratio of the length of the expansion section to the total length of the air film hole is: 0 <L e / L≤1.

[0011] Preferably, the flow direction inclination angle α of the air film hole has a value range of 30 degrees ≤ α ≤ 90 degrees, and the spanwise inclination angle of the expansion section has a value range of 30 degrees ≤ spanwise inclination angle ≤ 150 degrees.

[0012] Preferably, the ratio of the transverse hole spacing P between the air film holes and the adjacent air film holes to the diameter D of the cylindrical section is not less than 3.

[0013] Preferably, the cylindrical section and the expansion section are coaxially arranged.

[0014] Preferably, the C-shaped upstream rounded section and the C-shaped downstream rounded section on the same side are tangent to each other.

[0015] Preferably, the semi-major axis is: a1>a2, and the semi-minor axis is: b1>b2.

[0016] The present invention discloses the following technical effects:

[0017] 1. The present invention directly constructs a branching structure in the hole by controlling the outlet profile to induce the formation of an anti-kidney vortex, thereby more conveniently adjusting the shape of the air film hole; at the same time, by adjusting the outlet profile to change the expansion section, the structure of the air film hole can be enriched, with a larger sample space for structural optimization.

[0018] 2. The air film hole provided by the present invention combines the characteristics of the convergent slit-shaped hole, that is, the flow width of the outlet profile can be adjusted to make the hole shape shrink along the flow direction, so as to suppress the flow separation in the hole and reduce the aerodynamic loss.

[0019] 3. The air film holes provided by the present invention can form an ideal anti-kidney vortex structure, promote the lateral expansion of cold air, increase the coverage area of ​​the air film in the direction of extension, enhance the air film wall attachment effect, and thus improve the air film cooling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only 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.

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the outlet profile structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the top view of the structure of the present invention;

[0024] Figure 4 It is a schematic diagram of the front view structure of the present invention;

[0025] Figure 5 This is a schematic diagram of the axial structure of the present invention;

[0026] Figure 6 This is a schematic diagram of the hot end solid wall structure of the present invention;

[0027] Figure 7 The spanwise film cooling efficiency distribution curve at a downstream flow distance of 10D of the present invention is shown;

[0028] Figure 8 The spanwise film cooling efficiency distribution curve at a downstream flow distance of 20D of the present invention is shown;

[0029] Figure 9 This is a comparison curve of the spanwise average film cooling efficiency within a downstream flow distance of 40D according to the present invention;

[0030] Figure 10 The downstream vortex volume cloud diagram and velocity vector diagram of the present invention are at a distance of 15D from the downstream section;

[0031] Figure 11 The vorticity contour map and velocity vector map of the film hole at a distance of 15D downstream of the film hole shown in the Chinese invention patent application CN201310236780.5;

[0032] Figure 12The vorticity contour map and velocity vector map of the crescent-shaped air film hole at a distance of 15D in the downstream direction shown in Chinese invention patent application publication 202210520834.X;

[0033] Figure 13 This is the cooling effect cloud diagram within the range of 40D downstream of the air film hole of the present invention;

[0034] Figure 14 This is the cooling effect cloud diagram of the air film hole within a downstream flow distance of 40D shown in the Chinese invention patent application CN201310236780.5;

[0035] Figure 15 This is the cooling effect cloud diagram of the crescent-shaped air film hole within a downstream flow distance of 40D shown in Chinese invention patent application publication 202210520834.X;

[0036] Among them, 1. outlet profile; 2. expansion section; 3. inlet profile; 4. cylindrical section; 5. C-type upstream elliptical section; 6. C-type upstream rounded section; 7. C-type downstream rounded section; 8. C-type downstream elliptical section; 9. cooling gas; 10. hot end solid wall; 11. high-temperature mainstream. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Reference Figures 1-6 The present invention provides a C-shaped film hole cooling structure for a hot end component of a gas turbine, comprising a plurality of film holes formed on a hot end solid wall 10. The film holes are formed at an angle and include a cylindrical section 4. One end of the cylindrical section 4 is connected to an expansion section 2. A cold air inlet is provided at the end of the cylindrical section 4 away from the expansion section 2. An outlet profile 1 is provided at the end of the expansion section 2 away from the cylindrical section 4. The outlet profile 1 is a C-shaped cold air outlet. An inlet profile 3 is provided at the end of the expansion section 2 facing the cylindrical section 4. The outlet profile 1 and the inlet profile 3 are connected by a ruled surface to form a C-shaped expansion section 2.

[0040] The method for constructing the outlet profile 1 is as follows: obtain the intersection point O1 by intersecting the axis of the air film hole with the tangent plane of the outer surface of the hot end solid wall 10, mark point O2 at a flow direction distance L12 from O1, and use point O2 as the midpoint to draw two concentric ellipses with semi-major axes a1 and a2 and semi-minor axes b1 and b2 respectively. Draw the large ellipse through a1 and b1, and the small ellipse through a2 and b2; use the straight lines O1 and O2 as the symmetry axes to draw two flow direction auxiliary lines with a spacing of W, where W is the transverse outlet width of the air film hole; the large ellipse is rounded with the two auxiliary lines, with a rounding radius of R6, to form a C-type upstream ellipse segment 5 and a C-type upstream rounded segment 6, and the small ellipse is rounded with the two auxiliary lines, with a rounding radius of R7, to form a C-type downstream rounded segment 7 and a C-type downstream ellipse segment 8, and the outlet profile 1 is C-shaped.

[0041] The present invention directly constructs a branching structure in the hole by controlling the outlet profile 1 to induce the formation of an anti-kidney vortex, thereby more conveniently adjusting the shape of the air film hole; at the same time, by adjusting the outlet profile 1 to change the expansion section 2, the structure of the air film hole can be enriched and have a larger structural optimization sample space.

[0042] The air film hole provided by the present invention combines the characteristics of the convergent slit-shaped hole, that is, the flow width of the outlet profile 1 can be adjusted to make the hole shape shrink along the flow direction, so as to suppress flow separation in the hole and reduce aerodynamic losses.

[0043] The air film hole provided by the present invention can form an ideal anti-kidney vortex structure, promote the lateral expansion of cold air, increase the coverage area of ​​the air film in the extension direction, and enhance the wall attachment effect of the air film, thereby improving the cooling efficiency of the air film hole.

[0044] According to a further optimization scheme, the diameter D of the cylindrical section 4 is in the range of 0.4 mm ≤ D ≤ 1.0 mm.

[0045] Further optimization scheme, the ratio of the length of expansion section 2 to the total length of the air film hole is: 0 <L e / L≤1.

[0046] According to the further optimization scheme, the flow direction inclination angle α of the air film hole is in the range of 30 degrees ≤ α ≤ 90 degrees, and the spanwise inclination angle of the expansion section 2 is in the range of 30 degrees ≤ spanwise inclination angle ≤ 150 degrees.

[0047] According to a further optimization scheme, the ratio of the transverse hole spacing P between adjacent air film holes to the diameter D of the cylindrical section 4 is not less than 3.

[0048] According to a further optimized solution, the cylindrical section 4 and the expansion section 2 are coaxially arranged.

[0049] According to a further optimized solution, the C-shaped upstream rounded section 6 and the C-shaped downstream rounded section 7 on the same side are tangent to each other.

[0050] Further optimization scheme, semi-major axis: a1>a2, semi-minor axis: b1>b2.

[0051] The specific construction method of the outlet profile 1 is:

[0052] The intersection point O1 is obtained by intersecting the axis of the air film hole with the tangent plane of the hot end solid wall 10; the flow distance L from O1 is 12 Mark point O2 at 15mm, take point O2 as the midpoint, draw two concentric ellipses with semi-major axes a1 of 25mm, a2 of 20mm, and semi-minor axes b1 of 19mm and b2 of 11mm; take straight line O1O2 as the axis of symmetry, draw two flow auxiliary lines with a spacing W of 24mm, that is, the transverse outlet width of the air film hole is 24mm; the large ellipse is rounded with the two auxiliary lines, and the rounding radius R6 is 5.22mm, forming a C-type upstream elliptical segment 5 and a C-type upstream rounded segment 6, the small ellipse is rounded with the two auxiliary lines, and the rounding radius R7 is 3mm, forming a C-type downstream rounded segment 7 and a C-type downstream elliptical segment 8, the C-type upstream rounded segment 6 and the C-type downstream rounded segment 7 on the same side are tangent to each other; forming a C-shaped outlet profile 1.

[0053] Further optimization scheme, the air film hole is arranged on the hot end solid wall 10, the aperture D of the cylindrical section 4 is 10mm, the hole axis length L of the air film hole is 3D, and the length of the expansion section 2 accounts for the total length ratio L e / L is 3 / 5, the lateral spacing P between adjacent air film holes is 5D, the flow direction inclination angle α of the air film holes is 45 degrees, and no spanwise inclination angle is set; the cooling gas 9 is ejected from the cold air outlet formed by the inlet profile 3 through the cold air inlet, and the cooling gas 9 forms an air film covering the surface of the hot end solid wall 10, and at the same time mixes with the high-temperature mainstream 11 and is finally dissipated.

[0054] Reference Figure 7-Figure 15 The present invention numerically simulates the wall cooling efficiency of three types of hot end solid wall film cooling within the downstream 40D range for the air film hole shown in the Chinese invention patent application CN201310236780.5 and the crescent-shaped air film hole shown in the Chinese invention patent application 202210520834.X with the same outlet width; the working conditions used in the numerical simulation are: the mainstream aperture Reynolds number Re D =10000, mainstream turbulence Tu=1%, cooling air to mainstream density ratio DR=1.5, blowing ratio M=1.0; the calculation process uses UG modeling, FluentMeshing to generate unstructured grids, and the CFX solver is used to obtain the cooling efficiency and flow field characteristics.

[0055] Figure 7The spanwise film cooling efficiency distribution of the film hole of the present invention, the film hole shown in Chinese invention patent application publication CN201310236780.5 with the same outlet width, and the crescent-shaped film hole shown in Chinese invention patent application publication 202210520834.X with the same outlet width at a flow distance 10D downstream of the film hole.

[0056] Figure 8 The spanwise film cooling efficiency distribution of the film hole of the present invention and the film hole shown in Chinese invention patent application publication CN201310236780.5 with the same outlet width, and the crescent-shaped film hole shown in Chinese invention patent application publication 202210520834.X with the same outlet width at a flow distance 20D downstream of the film hole.

[0057] The horizontal axis represents the distance in the span direction, and the vertical axis represents the air film cooling efficiency. It can be seen that at the two flow positions 10D and 20D downstream of the air film hole, the air film hole of the present invention has a better span-wise coverage effect, and the anti-kidney vortex formed is stronger, thereby promoting the cold air to extend from the center line to both sides. Therefore, the cooling efficiency near the center line is lower, and the air film span-wise coverage width is wider and the coverage is more uniform. This fully demonstrates the effectiveness and superiority of this patent.

[0058] Figure 9 It is the spanwise average film cooling efficiency distribution of the film hole of the present invention and the film hole shown in Chinese invention patent application CN201310236780.5 with the same outlet width, and the crescent-shaped film hole shown in Chinese invention patent application 202210520834.X with the same outlet width within a flow distance of 40D downstream of the film hole.

[0059] The horizontal axis represents the distance in the flow direction, and the vertical axis represents the span-wise average air film cooling efficiency. It can be seen that the C-type air film hole of this embodiment has the highest span-wise average air film cooling efficiency in the downstream area where x / D>3. Compared with the other two hole types, the air film cooling efficiency is improved by about 15%, which fully demonstrates the effectiveness and superiority of this patent.

[0060] Figure 10-12 , respectively showing the flow vortex cloud diagram and velocity vector diagram of the air film hole of the present invention, the air film hole shown in the Chinese invention patent application publication CN201310236780.5 with the same outlet width, and the crescent-shaped air film hole shown in the Chinese invention patent application publication 202210520834.X with the same outlet width in the plane 15D downstream of the air film hole.

[0061] It can be seen that the air film hole of the present invention forms an anti-kidney vortex structure downstream which is beneficial to the cooling of the air film. The anti-kidney vortex is stronger than the kidney vortex, which promotes the lateral expansion of the cold air and improves the wall attachment effect of the air film. The anti-kidney vortex structure formed by the other two hole types is relatively weak, and the kidney vortex still dominates the flow of cold air; this fully demonstrates the effectiveness and superiority of this patent.

[0062] Figure 13-15 , respectively showing the cooling effect cloud diagrams of the air film hole of the present invention, the air film hole shown in Chinese invention patent application publication CN201310236780.5 with the same outlet width, and the crescent-shaped air film hole shown in Chinese invention patent application publication 202210520834.X with the same outlet width within a flow distance of 40D downstream of the air film hole.

[0063] It can be seen that the air film wake of the air film hole of the present invention forms two high cooling efficiency areas extending in the flow direction under the action of the anti-kidney vortex, so the air film has a wider coverage range in the span direction and a better air film cooling effect.

[0064] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0065] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A C-type film hole cooling structure for a hot end component of a gas turbine, characterized by: The invention comprises a plurality of air film holes provided on a hot end solid wall (10), wherein the air film holes are provided at an angle, and the air film holes include a cylindrical section (4), one end of the cylindrical section (4) is connected to an expansion section (2), an end of the cylindrical section (4) away from the expansion section (2) is provided with a cold air inlet, an end of the expansion section (2) away from the cylindrical section (4) is provided with an outlet profile (1), the outlet profile (1) is a C-shaped cold air outlet, an end of the expansion section (2) facing the cylindrical section (4) is provided with an inlet profile (3), and the outlet profile (1) and the inlet profile (3) are connected by a ruled surface to form the C-shaped expansion section (2); The method for constructing the outlet profile (1) is as follows: an intersection O1 is obtained by intersecting the axis of the air film hole with the tangent plane of the outer surface of the hot end solid wall (10), and a flow direction distance L from O1 is obtained. 12 Mark point O2 at the center, take point O2 as the midpoint, draw two concentric ellipses with semi-major axes a1 and a2 and semi-minor axes b1 and b2 respectively, draw a large ellipse through a1 and b1, and draw a small ellipse through a2 and b2; take straight lines O1 and O2 as symmetry axes, draw two flow direction auxiliary lines with a spacing of W, W is the transverse outlet width of the air film hole; the large ellipse is rounded with the two auxiliary lines, and the rounding radius is R6, forming a C-type upstream ellipse segment (5) and a C-type upstream rounded segment (6); the small ellipse is rounded with the two auxiliary lines, and the rounding radius is R7, forming a C-type downstream rounded segment (7) and a C-type downstream ellipse segment (8), and the outlet profile (1) is C-shaped; The cylindrical section (4) and the expansion section (2) are coaxially arranged; The C-shaped upstream rounded section (6) and the C-shaped downstream rounded section (7) on the same side are tangent to each other; Semi-major axis: a1>a2, semi-minor axis: b1>b2.

2. The C-shaped film hole cooling structure for a gas turbine hot end component according to claim 1, characterized in that: The diameter D of the cylindrical section (4) has a value range of: 0.4 mm ≤ D ≤ 1.0 mm.

3. The C-shaped film hole cooling structure for a gas turbine hot end component according to claim 1, characterized in that: The ratio of the length of the expansion section (2) to the total length of the air film hole is: 0 <L e / L≤1.

4. The C-shaped film hole cooling structure for a gas turbine hot end component according to claim 1, characterized in that: The range of the flow direction inclination angle α of the air film hole is: 30 degrees ≤ α ≤ 90 degrees, and the range of the spanwise inclination angle of the expansion section (2) is: 30 degrees ≤ spanwise inclination angle ≤ 150 degrees.

5. The C-shaped film hole cooling structure for a gas turbine hot end component according to claim 1, characterized in that: The ratio of the transverse hole spacing P between the air film holes and the adjacent air film holes to the diameter D of the cylindrical section (4) is not less than 3.

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