A semi-split cooling structure applied to a turbine blade trailing edge

Abstract

The application relates to a half-split cooling structure applied to a turbine blade tail edge, which comprises a blade pressure surface, a blade suction surface and a tail edge part, the tail edge part comprises a cold gas inlet, a tail slit, a separation rib and a half-split outlet wall surface, a spoiler part is arranged between the cold gas inlet and the tail slit, two ends of the spoiler part are connected with the blade pressure surface and the inner side wall of the blade suction surface respectively, the spoiler part plays a disturbing role on the cold gas entering the cold gas inlet, a zigzag cooling part is arranged on the half-split outlet wall surface, the zigzag cooling part is located between the tail slit and the separation rib, the zigzag cooling part comprises a plurality of interval distributed bosses and grooves, the bosses and the grooves are all in trapezoidal structures, the uneven distribution of the air film of the tail edge part of the turbine blade due to the plurality of separation ribs is effectively inhibited, and in a word, the technical problems of the unevenness of the air film distribution downstream of the half-split outlet, the spanwise covering effect of the cooling air film and the low cooling efficiency are solved, and the application has the advantages of simple structure, convenient processing and good cooling effect.

Description

Technical Field

[0001] This invention belongs to the field of gas turbine blade design technology, specifically relating to a semi-slit cooling structure applied to the trailing edge of a turbine blade. Background Technology

[0002] The turbine inlet temperature of a gas turbine is a crucial parameter affecting engine performance, and increasing the turbine inlet temperature can be a shortcut to achieving greater power output. Currently, the turbine inlet temperature of advanced aero engines reaches as high as 2000K, far exceeding the temperature resistance limit of turbine blade materials. Therefore, efficient cooling technologies must be employed to ensure its normal operation. The trailing edge of the turbine blade is heavily influenced by the mainstream, resulting in high convective heat transfer intensity and high thermal load. Therefore, the trailing edge is a challenging area for turbine blade cooling. How to efficiently cool the trailing edge is a very important factor in reducing the blade surface temperature and extending the blade's service life.

[0003] Currently, turbine blade trailing edge regions are generally cooled using internal channels. To enhance heat transfer and increase structural strength, turbulence structures such as turbulence columns and ribs are usually arranged inside the channels. This results in the trailing edge typically requiring a certain wall thickness to function. However, from the perspective of reducing blade aerodynamic losses, stress actually requires reducing the trailing edge thickness. This is because increasing the trailing edge thickness will lead to an increase in trailing edge width and flow resistance. From a cooling perspective, an excessively small trailing edge thickness makes it difficult to design and organize the required amount of cold air, which can lead to overheating. Therefore, the design of the trailing edge thickness affects the entire turbine blade's performance. Currently, the semi-slit cooling structure is a widely used cooling structure for turbine blades, representing a compromise between aerodynamic performance and cooling issues. The principle of the semi-slit cooling structure is to cut off a portion of the wall on one side of the blade's trailing edge pressure surface, introducing the cold air from the internal channels into the cut-off wall to form a cooling air film, thereby achieving a cooling effect through the cooling air film.

[0004] However, existing semi-slit cooling structures still have many problems in use. First, semi-slit cooling structures with spacer ribs will have uneven air film distribution in the downstream region, and their air film cooling efficiency will drop rapidly. This may lead to an increase in the highest temperature and temperature gradient in the downstream region of the semi-slit and a corresponding increase in thermal stress, which in turn will damage the trailing edge structure. Therefore, there is a technical need to improve the air film cooling efficiency and distribution uniformity in the downstream region of the semi-slit outlet without increasing the amount of cooling gas. Solving the corresponding problems can also greatly improve the performance of aero engines.

[0005] Therefore, there is an urgent need for a semi-slit cooling structure for turbine blade trailing edge to solve the technical problems of uneven distribution of air film downstream of the semi-slit outlet, low spanwise coverage of cooling air film, and low cooling efficiency in the existing technology. Summary of the Invention

[0006] In view of this, the present invention proposes a semi-slit cooling structure for the trailing edge of turbine blades. When applied to gas turbine blades, it solves the existing technical problems of uneven distribution of the gas film downstream of the semi-slit outlet, as well as low longitudinal coverage and cooling efficiency of the cooling gas film. This effectively reduces the highest temperature and temperature gradient at the trailing edge, resulting in not only good cooling effect but also a simplified structure and convenient processing. It has high application and promotion value.

[0007] To achieve the above-mentioned technical objectives, the specific technical solution adopted by the present invention is as follows:

[0008] A semi-slit cooling structure for turbine blade trailing edge includes a blade pressure surface, a blade suction surface, and a trailing edge. The trailing edge is located on an extension of the blade suction surface and includes a cold air inlet, a trailing slit, a partition rib, and a semi-slit outlet wall. The trailing slit is located between the end of the blade pressure surface and the blade suction surface. The cold air inlet is located on the side of the trailing slit away from the semi-slit outlet wall. Multiple partition ribs are located between the trailing slit and the end of the blade suction surface, and are evenly distributed along the height direction of the turbine blade. A turbulence section is provided between the cold air inlet and the trailing slit, with both ends connected to the inner walls of the blade pressure surface and the blade suction surface, respectively, to turbulence the cold air entering through the cold air inlet. A serrated cooling section is provided on the semi-slit outlet wall, located between the trailing slit and the partition rib. The serrated cooling section includes multiple spaced bosses and grooves, both of which are trapezoidal in structure.

[0009] Furthermore, there are multiple semi-slit outlet walls, which are evenly distributed along the height direction of the turbine blades. Each semi-slit outlet wall and its corresponding partition rib are spaced apart on the trailing edge.

[0010] Furthermore, a cold air channel is provided between the cold air inlet and the tail slit, and a turbulence part is provided in the cold air channel. The turbulence part includes a transverse support shaft and two rectangular turbulence strips provided on the transverse support shaft. The transverse support shaft is provided perpendicular to the inner wall of the cold air channel, and the two rectangular turbulence strips are provided perpendicular to the transverse support shaft and are evenly distributed along the extension direction of the transverse support shaft. The two rectangular turbulence strips are staggered in the cross section perpendicular to the transverse support shaft.

[0011] Furthermore, the two rectangular spoiler strips form an angle of 30° to 90° on the cross section perpendicular to the transverse support axis, and the connection between the rectangular spoiler strips and the transverse support axis is a smooth arc transition.

[0012] Furthermore, the turbulence section consists of multiple groups, which are evenly distributed along the height direction of the turbine blades.

[0013] Furthermore, the bottom edge of the boss and the groove is parallel to the wall surface of the semi-split outlet, and the waist edge of the boss and the groove has an angle of 120° to 165° with the bottom edge.

[0014] Furthermore, the width of the semi-slit outlet wall is D, the height t1 / D of the boss of the sawtooth cooling part from the semi-slit outlet wall is 1 / 5 to 1 / 3, the height t1 / D of the groove of the sawtooth cooling part from the wall is 1 / 5 to 1 / 3, the width S1 / D of the boss is 0.5 to 1.0, and the width S2 / D of the groove is 0.5 to 1.0.

[0015] Furthermore, the ratio of the horizontal extension length L1 of the serrated cooling upper boss and groove to the total length L of the tail edge half-slit outlet wall is 0.4 to 0.6.

[0016] Furthermore, the angle between the trailing edge semi-slit wall and the blade trailing edge pressure surface is 5° to 35°.

[0017] Furthermore, the width of the tail slit is W, the height of the tail slit is H, the ratio of the tail slit width to the width of the half-split exit wall is W / D, which is 2 to 4, and the ratio of the tail slit height H to the width of the half-split exit wall is H / D, which is 1 to 2.

[0018] Furthermore, the front pressure plate is provided with a rectangular through hole to accommodate the rotating trigger and facilitate the up and down movement of the rotating trigger.

[0019] By adopting the above technical solution, the present invention can also bring the following beneficial effects:

[0020] 1. This invention disrupts the boundary layer of the blade's suction surface through a serrated cooling section. The protrusions and grooves facilitate the cooling air exiting the cooling channel, ensuring it adheres closely to the semi-slit outlet wall after exiting. This results in a stronger spanwise flow of the generated cooling air film, reducing uneven cooling air film coverage, improving the cooling efficiency of the exiting air, and effectively suppressing the uneven distribution of the air film at the trailing edge of the turbine blade caused by multiple partition ribs. Furthermore, the formed cooling air film effectively separates the high-temperature mainstream of the blade's trailing edge pressure surface from the semi-slit outlet wall, protecting the blade's suction surface and increasing the service life of the trailing edge.

[0021] 2. This invention, by setting a turbulence section in the cold air channel, not only increases the heat exchange area, but also increases the mixing of cold air in different areas due to the disturbance of the flow, significantly improving the heat exchange effect. The turbulence of the cold air entering from the cold air inlet inside the cold air channel increases the time the cold air spends in the cold air channel, enhancing the heat dissipation of the cold air channel, thereby protecting the pressure surface of the blades. Moreover, the distribution of rectangular turbulence strips on the transverse support axis further enhances the airflow turbulence effect, thereby reducing the speed of the cold air exiting the tail slit, making it easier for the cold air exiting the tail slit to generate a corresponding cooling air film on the semi-slit outlet wall. It has the advantages of simple structure, convenient processing, and good cooling effect. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 As a specific embodiment of the present invention, the present invention Figure 1 AA section view;

[0025] Figure 3 As a specific embodiment of the present invention, the present invention Figure 1 BB section view;

[0026] Figure 4 For the present invention Figure 3 A magnified view of a portion of the image;

[0027] Figure 5 This is a schematic diagram of the semi-slit cooling section at the trailing edge of the turbine blade in a specific embodiment of the present invention;

[0028] Figure 6 This is a distribution diagram of the film gas efficiency at the semi-slit edge of the turbine blade in this invention.

[0029] Figure 7 This is a diagram showing the film efficiency distribution at the trailing edge of a conventional turbine blade with a semi-slit.

[0030] Figure 8 The curve showing the spanwise average film cooling efficiency of the semi-slit outlet wall in the serrated cooling section of the present invention and the conventional semi-slit outlet wall is a comparison curve.

[0031] Among them: 1. Blade suction surface; 2. Blade pressure surface; 3. Trailing edge; 4. Cold air inlet; 5. Tail slot; 6. Separating rib; 7. Semi-slit outlet wall; 8. Serrated cooling section; 9. Boss; 10. Groove; 11. Turbid section; 12. Rectangular turbulence strip; 13. Cold air passage; 14. Lateral support shaft. Detailed Implementation

[0032] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0035] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0036] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0037] In one embodiment of the present invention, such as Figures 1 to 8 As shown, a semi-slit cooling structure applied to the trailing edge of a turbine blade includes a blade pressure surface 2, a blade suction surface 1, and a trailing edge portion 3. The trailing edge portion 3 is disposed on an extension of the blade suction surface 1. The trailing edge portion 3 includes a cold air inlet 4, a trailing slit 5, a partition rib 6, and a semi-slit outlet wall 7. The trailing slit 5 is disposed between the end of the blade pressure surface 2 and the blade suction surface 1. The cold air inlet 4 is disposed on the side of the trailing slit 5 away from the semi-slit outlet wall 7. The partition rib 6 is disposed between the end of the blade suction surface 1 and the blade suction surface 1. There are multiple partition ribs 6, which are evenly distributed along the height direction of the turbine blade. There are multiple semi-slit outlet walls 7, which are evenly distributed along the height direction of the turbine blade. Each semi-slit outlet wall 7 and the corresponding partition rib 6 are spaced apart on the trailing edge portion 3.

[0038] A turbulence section 11 is provided between the cold air inlet 4 and the tail slit 5. The two ends of the turbulence section 11 are connected to the inner walls of the blade pressure surface 2 and the blade suction surface 1, respectively, to turbulence the cold air entering through the cold air inlet 4. There are multiple sets of turbulence sections 11, which are evenly distributed along the height direction of the turbine blade. A cold air passage 13 is provided between the cold air inlet 4 and the tail slit 5, and the turbulence section 11 is located in the cold air passage 13. The turbulence section 11 includes a transverse support shaft 14 and two components mounted on the transverse support shaft 14. The rectangular baffle strips 12 are arranged perpendicular to the inner wall of the air conditioning channel 13, with the transverse support axis 14 perpendicular to the transverse support axis 14. The two rectangular baffle strips 12 are evenly distributed along the extension direction of the transverse support axis 14. The two rectangular baffle strips 12 are staggered in the cross section perpendicular to the transverse support axis 14. The two rectangular baffle strips 12 form a 60° angle in the cross section perpendicular to the transverse support axis 14. The connection between the rectangular baffle strips 12 and the transverse support axis 14 is a smooth arc transition.

[0039] A serrated cooling section 8 is provided on the semi-slit outlet wall 7. The serrated cooling section 8 is located between the tail slit 5 and the partition rib 6. The serrated cooling section 8 includes multiple spaced bosses 9 and grooves 10, both of which are trapezoidal in structure. The bottom edge of the bosses 9 and grooves 10 is parallel to the semi-slit outlet wall 7, and the angle between the waist edge and the bottom edge of the bosses 9 and grooves 10 is 150°.

[0040] The width of the semi-slit outlet wall 7 is D. The height t1 / D of the boss 9 of the serrated cooling section 8 from the semi-slit outlet wall 7 is 1 / 4. The height t1 / D of the groove 10 of the serrated cooling section 8 from the wall is 1 / 4. The width S1 / D of the boss 9 is 0.8. The width S2 / D of the groove 10 is 0.8. The ratio of the horizontal extension length L1 of the boss 9 and groove 10 of the serrated cooling section to the total length L of the trailing edge semi-slit outlet wall 7 is 0.5. The angle between the trailing edge semi-slit wall and the blade trailing edge pressure surface is 30°. The width of the tail slit 5 is W. The height of the tail slit 5 is H. The ratio W / D of the width of the tail slit 5 to the width of the semi-slit outlet wall 7 is 4. The ratio H / D of the height H of the tail slit 5 to the width of the semi-slit outlet wall 7 is 2.

[0041] In the calculation process of this invention, the actual Nusselt number of the cold air passage 13 is calculated based on the Reynolds number, Prandtl number, and initial design dimensions of the cold air passage 13;

[0042] Nu = 0.248Re 0.6 Pr 0.333

[0043] Re=(q4A p ) / (μA C U)

[0044] Where q is the flow rate of the cold air passage 13, and A p Cross-sectional area of ​​the turbulence element, μ, dynamic viscosity coefficient, A C The flow area of ​​the cold air passage 13, where U is the wetted perimeter length of the turbulence unit;

[0045] Based on the boss 9 and groove 10 of the serrated cooling section 8 and the initial design dimensions, the actual Nusselt number Nu = 0.018Re is calculated. 0.8 Cr,

[0046] Wherein Cr is the heat transfer correction coefficient of the turbulence section 11, and Cr is 2.2.

[0047] Determine whether the deviation between the actual nusselt number and the designed nusselt number of the trailing edge 3 is within a preset range. If the deviation is within the preset range, the requirement is met; otherwise, adjust the design dimension parameters until the deviation meets the requirement.

[0048] In verifying the effectiveness of this invention, the film cooling efficiency at the outlet wall of the semi-slit with the serrated cooling section 8 of this invention and the conventional semi-slit were calculated. The calculations used UG modeling, FluentMeshing to generate unstructured meshes, and the CFX solver. The calculated spanwise film cooling efficiencies are as follows: Figures 6-8This invention provides a definition of film cooling effect, and the specific formula is as follows:

[0049] η=(T g -T w (T) g -T c )

[0050] In the formula T g T represents the total gas temperature. w T is the wall temperature. c This refers to the air conditioning temperature.

[0051] The horizontal axis represents the ratio of the distance L from the semi-slit outlet wall 7 of the tail slit 5 to the height D of the tail slit 5, and the vertical axis represents the cooling efficiency of the air film. Thus, it can be concluded that the air film cooling efficiency of the semi-slit outlet wall 7 with the sawtooth cooling section 8 of this embodiment is increased by 15%, which fully demonstrates the effectiveness and superiority of the present invention.

[0052] In use, the cold air entering between the blade pressure surface 2 and the blade suction surface 1 enters the cold air channel 13 through the cold air inlet 4. Then, after being disturbed by the turbulence part 11 inside the cold air channel 13, the passage path of the cold air in the cold air channel 13 is increased, and the speed of the cold air passing through the cold air channel 13 is reduced. While facilitating heat exchange between the cold air channel 13 and the blade pressure surface 2, the speed of the cold air discharged from the tail slit 5 is further reduced. The cold air discharged from the tail slit 5 passes through the protrusion 9 and groove 10 on the semi-slit outlet wall 7, so that the cold air forms a cold air film on the semi-slit outlet wall 7, thereby reducing the interference of the separating rib 6 on the tail edge 3, enhancing the cooling effect of the tail edge 3, and effectively reducing the maximum temperature and temperature gradient of the turbine blade tail edge. In summary, the present invention solves the existing technical problems of uneven distribution of the downstream air film at the semi-slit outlet and low spanwise coverage effect and cooling efficiency of the cooling air film. It has the advantages of simple structure, convenient processing and good cooling effect.

[0053] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A semi-slit cooling structure applied to the trailing edge of a turbine blade, characterized in that: The device includes a blade pressure surface (2), a blade suction surface (1), and a trailing edge (3). The trailing edge (3) is located on an extension of the blade suction surface (1). The trailing edge (3) includes a cold air inlet (4), a tail slit (5), a partition rib (6), and a semi-slit outlet wall (7). The tail slit (5) is located between the end of the blade pressure surface (2) and the blade suction surface (1). The cold air inlet (4) is located on the side of the tail slit (5) away from the semi-slit outlet wall (7). The partition rib (6) is located between the end of the blade pressure surface (2) and the end of the blade suction surface (1). There are multiple partition ribs (6). The partition ribs (6) are evenly distributed along the height direction of the turbine blades. A turbulence section (11) is provided between the cold air inlet (4) and the tail slit (5). The two ends of the turbulence section (11) are connected to the inner walls of the blade pressure surface (2) and the blade suction surface (1), respectively, which turbulent the cold air entering through the cold air inlet (4). A sawtooth cooling section (8) is provided on the semi-slit outlet wall (7). The sawtooth cooling section (8) is located between the tail slit (5) and the partition ribs (6). The sawtooth cooling section (8) includes multiple spaced bosses (9) and grooves (10). Both the bosses (9) and the grooves (10) are trapezoidal structures. A cold air channel (13) is provided between the cold air inlet (4) and the tail slit (5). The turbulence part (11) is provided in the cold air channel (13). The turbulence part (11) includes a transverse support shaft (14) and two rectangular turbulence strips (12) provided on the transverse support shaft (14). The transverse support shaft (14) is provided perpendicular to the inner wall of the cold air channel (13). The two rectangular turbulence strips (12) are provided perpendicular to the transverse support shaft (14) and are evenly distributed along the extension direction of the transverse support shaft (14). The two rectangular turbulence strips (12) are staggered in the cross section perpendicular to the transverse support shaft (14).

2. The semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 1, characterized in that: There are multiple semi-slit outlet walls (7), which are evenly distributed along the height direction of the turbine blade. Each semi-slit outlet wall (7) and the corresponding partition rib (6) are distributed at intervals on the trailing edge (3).

3. The semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 1, characterized in that: The two rectangular baffle strips (12) form an angle of 30° to 90° on the cross section perpendicular to the transverse support axis (14), and the connection position of the rectangular baffle strips (12) and the transverse support axis (14) forms a smooth arc transition.

4. The semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 3, characterized in that: The turbulence-disrupting part (11) is in multiple groups, and the multiple groups of turbulence-disrupting parts (11) are evenly distributed along the height direction of the turbine blade.

5. A semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 4, characterized in that: The bottom edge of the boss (9) and the groove (10) is parallel to the wall surface (7) of the half-slit outlet, and the waist edge of the boss (9) and the bottom edge of the groove (10) form an angle of 120° to 165°.

6. A semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 5, characterized in that: The width of the semi-slit outlet wall (7) is D. The ratio of the height t1 of the boss (9) of the sawtooth cooling part (8) from the semi-slit outlet wall (7) to the width D of the semi-slit outlet wall (7) is 1 / 5 to 1 / 3. The ratio of the height t2 of the groove (10) of the sawtooth cooling part (8) from the wall to the width D of the semi-slit outlet wall (7) is 1 / 5 to 1 / 3. The ratio of the width S1 of the boss (9) to the width D of the semi-slit outlet wall (7) is 0.5 to 1.

0. The ratio of the width S2 of the groove (10) to the width D of the semi-slit outlet wall (7) is 0.5 to 1.

0.

7. A semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 6, characterized in that: The ratio of the horizontal extension length L1 of the boss (9) and groove (10) on the sawtooth cooling section (8) to the total length L of the tail edge half-slit outlet wall (7) is 0.4 to 0.

6.

8. A semi-slit cooling structure applied to the trailing edge of a turbine blade according to claim 1, characterized in that: The width of the tail slit (5) is W, the height of the tail slit (5) is H, the ratio of the width of the tail slit (5) to the width of the half-split outlet wall (7) W / D is 2 to 4, and the ratio of the height of the tail slit (5) H to the width of the half-split outlet wall (7) H / D is 1 to 2.

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