A turbine blade cooling structure for improving the cooling capacity of the blade tip

Abstract

The application provides a turbine blade cooling structure for improving blade tip cooling capacity, belonging to the technical field of aero-engine turbine blades. A partition plate is arranged on one side of the blade inside close to the blade tip. The partition plate divides a chamber into a blade tip cooling chamber and a blade body cooling chamber. A blade tip gas supply passage which communicates with the blade tip cooling chamber is arranged in the blade body cooling chamber. A blade body gas supply passage which communicates with the blade body cooling chamber is arranged at the blade root of the blade. An annular spacing wall is arranged on one side of the blade tip cooling chamber close to the blade leading edge. The outer wall of the annular spacing wall and the inner wall of the blade tip cooling chamber are arranged in a spaced mode. A gap is arranged on one side of the annular spacing wall close to the blade leading edge to form an impact throat. The communication position of the blade tip gas supply passage and the blade tip cooling chamber is located in the range of the annular spacing wall. Through the processing scheme, the high-efficiency cooling of the turbine blade can be ensured under the high-temperature airflow condition, and the blade tip cooling failure and blade tip ablation can be avoided.

Description

Technical Field

[0001] This application relates to the field of aero-engine turbine blades, and in particular to a turbine blade cooling structure that improves tip cooling capacity. Background Technology

[0002] To achieve higher efficiency and thrust-to-weight ratio in aero-engines, turbine inlet temperatures are gradually increasing at a rate of approximately 20K per year. Current advanced aero-engines have turbine inlet temperatures exceeding 2200K, far surpassing turbine blade operating temperatures. Therefore, more efficient turbine blade cooling technologies are urgently needed to ensure the safe and reliable operation of turbine blades. The blade tip region is a challenging area for turbine blade cooling, often experiencing hot spots and even ablation. This is partly because the blade tip region is typically the end of the leading edge or mid-chord cooling channel. After flowing through the cooling channel that runs through the blade body, the cooling air temperature rises, and the cooling capacity decreases. Furthermore, as the cold air flows out of the film cooling holes, the cold air flow rate gradually decreases along the blade height, reducing heat transfer capacity. On the other hand, the typical cooling design for the blade tip region is simple convection and film cooling, which has insufficient cooling potential. Summary of the Invention

[0003] In view of this, this application provides a turbine blade cooling structure that improves the tip cooling capacity, which solves the problems in the prior art and can ensure efficient cooling of turbine blades under high-temperature inflow conditions, avoiding cooling failure and tip ablation.

[0004] The turbine blade cooling structure for improving tip cooling capacity provided in this application adopts the following technical solution:

[0005] A turbine blade cooling structure for improving tip cooling capacity includes a hollow interior forming a cooling cavity. A baffle plate is located on the side of the blade near the tip, dividing the cavity into a tip cooling cavity between the baffle plate and the tip, and a blade cooling cavity between the baffle plate and the blade root. The blade cooling cavity has a tip air supply channel connecting to the tip cooling cavity. One end of the tip air supply channel extends to the blade root to connect to a cold air source. The blade root also has a blade air supply channel connecting to the blade cooling cavity and the cold air source. Both the blade cooling cavity and the tip cooling cavity have trailing edge slits on their trailing edge sides.

[0006] The blade tip cooling chamber has an annular partition wall on the side near the leading edge of the blade. One end of the annular partition wall is integrally formed with the partition plate, and the other end of the annular partition wall is integrally formed with the inner top wall of the blade. The outer wall of the annular partition wall and the inner wall of the blade tip cooling chamber are spaced apart. The side of the annular partition wall near the leading edge of the blade has a notch to form an impact throat. A pressure surface swirling channel is formed between the annular partition wall and the inner wall of the blade tip cooling chamber corresponding to the pressure surface of the blade. A suction surface swirling channel is formed between the annular partition wall and the inner wall of the blade tip cooling chamber corresponding to the suction surface of the blade. The connection between the blade tip air supply channel and the blade tip cooling chamber is located within the range of the annular partition wall. After the cold air entering the blade tip air supply channel enters the annular partition wall, it impacts the inner wall of the leading edge of the blade tip cooling chamber through the impact throat. The cold air impacting the inner wall of the leading edge of the blade tip cooling chamber flows towards the trailing edge of the blade tip cooling chamber through the pressure surface swirling channel and the suction surface swirling channel, and finally flows out through the trailing edge slit.

[0007] Optionally, the annular partition wall facing the blade pressure surface and the inner wall of the blade tip cooling chamber facing the blade pressure surface have the same curvature change trend and contour direction, and the annular partition wall facing the blade suction surface and the inner wall of the blade tip cooling chamber facing the blade suction surface have the same curvature change trend and contour direction.

[0008] Optionally, the sidewall of the annular spacer facing the blade pressure surface and the sidewall facing the blade suction surface are connected by an arc-shaped transition segment.

[0009] Optionally, the curvature variation trend and contour direction of the inner wall surface of the blade tip cooling chamber and the outer wall surface of the blade are the same at the same blade height position;

[0010] At the same blade height, the mid-arc line of the blade tip cooling chamber is located on the mid-arc line of the outer wall of the blade. At the same blade height, the mid-arc line of the annular spacer wall is located on the mid-arc line of the blade tip cooling chamber. The intersection of the outer wall of the arc segment and the mid-arc line of the blade tip cooling chamber is the dividing point. The mid-arc line of the dividing point and the leading edge of the blade tip cooling chamber accounts for 30-50% of the total mid-arc line length of the blade tip cooling chamber.

[0011] Optionally, the maximum inscribed circle of the inner wall profile of the annular partition wall and the maximum inscribed circle of the inner wall profile of the blade tip cooling cavity are concentric.

[0012] Optionally, the annular partition wall is provided with a V-shaped rib fixed on the partition plate. The V-shaped rib is located between the connection position of the blade tip air supply channel and the blade tip cooling chamber and the leading edge of the blade. The concave surface of the V-shaped rib faces the air outlet side of the blade tip air supply channel.

[0013] Optionally, the annular partition wall is provided with two V-shaped ribs, which are distributed along the mid-arc line of the blade, and the tip of the V-shaped rib near the leading edge faces the impact throat.

[0014] Optionally, the blade tip cooling chamber is provided with a plurality of guide pin ribs between the annular spacer wall and the trailing edge of the blade.

[0015] Optionally, the pressure surface of the blade is provided with multiple pressure surface air film holes that communicate with the blade tip cooling chamber, and the suction surface of the blade is provided with suction surface air film holes that communicate with the blade tip cooling chamber.

[0016] Optionally, the blade tip wall is provided with multiple blade tip dust removal holes that communicate with the blade tip cooling chamber.

[0017] In summary, this application includes the following beneficial technical effects:

[0018] This application achieves efficient cooling design for turbine blade tip by implementing separate cooling air supply and dual-swirl enhanced cooling design for the turbine blade tip region, effectively solving design problems such as difficulty in cooling the turbine blade tip region and local overheating under high-temperature inlet flow conditions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram showing the distribution structure of the blade tip cooling chamber, blade body cooling chamber, and blade tip air supply channel;

[0021] Figure 2 This is a schematic diagram showing the distribution structure of each cooling chamber within the turbine blade of this application;

[0022] Figure 3 This is a schematic diagram of the blade tip cooling chamber of this application.

[0023] Explanation of reference numerals in the attached drawings: 1. Baffle; 2. Blade tip cooling chamber; 21. Annular partition wall; 22. Impact throat; 23. Pressure surface swirl channel; 24. Suction surface swirl channel; 25. V-shaped rib; 26. Guide pin rib; 27. Pressure surface film gas hole; 28. Suction surface film gas hole; 29. ​​Blade tip dust removal hole; 3. Blade tip air supply channel; 4. Blade body cooling chamber; 41. First mid-chord cooling chamber; 42. Second mid-chord cooling chamber; 43. Leading edge cooling chamber; 44. Trailing edge cooling chamber; 45. First air supply chamber; 46. Second air supply chamber; 5. Trailing edge slit. Detailed Implementation

[0024] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0025] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application 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 this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] 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 application, 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 structures and / or functionalities other than one or more of the aspects set forth herein.

[0027] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In 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.

[0028] 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.

[0029] This application provides a turbine blade cooling structure to improve tip cooling capacity.

[0030] like Figure 1 , Figure 2 and Figure 3As shown, a turbine blade cooling structure for improving tip cooling capacity is disclosed. The blade has a hollow interior forming a cooling cavity. A baffle 1 is provided on the side of the blade near the tip, dividing the cavity into a tip cooling cavity 2 located between the baffle 1 and the tip, and a blade cooling cavity 4 located between the baffle 1 and the blade root. The blade cooling cavity 4 has a tip air supply channel 3 that connects to the tip cooling cavity 2. The end of the tip air supply channel 3 away from the tip cooling cavity 2 extends to the blade root to connect to a cold air source. The blade has a blade air supply channel at the blade root that connects to the blade cooling cavity 4 and is connected to a cold air source. Both the blade cooling cavity 4 and the tip cooling cavity 2 have trailing edge slits 5 on their trailing edge sides.

[0031] The blade tip cooling chamber 2 has an annular partition wall 21 located near the leading edge of the blade. One end of the annular partition wall 21 is integrally formed with the partition plate 1, and the other end is integrally formed with the inner top wall of the blade. The outer wall of the annular partition wall 21 and the inner wall of the blade tip cooling chamber 2 are spaced apart. The side of the annular partition wall 21 near the leading edge of the blade has a notch forming an impact throat 22. A pressure surface swirling channel 23 is formed between the annular partition wall 21 and the inner wall of the blade tip cooling chamber 2 corresponding to the pressure surface of the blade. A suction surface swirling channel 24 is formed between the annular partition wall 21 and the inner wall of the blade tip cooling chamber 2 corresponding to the suction surface of the blade. The connection between the blade tip air supply channel 3 and the blade tip cooling chamber 2 is located within the range of the annular partition wall 21. Figure 2 As shown, the cool air enters the blade tip air supply channel 3 from the blade root and then enters the blade tip cooling chamber 2. Figure 2 The arrows in the image indicate the direction of the cold air flow; for example... Figure 3 As shown, the cold air entering the blade tip air supply channel 3 enters the annular partition wall 21 and then impacts the inner wall of the leading edge of the blade tip cooling chamber 2 through the impact throat 22. The cold air impacting the inner wall of the leading edge of the blade tip cooling chamber 2 flows towards the trailing edge of the blade tip cooling chamber 2 through the pressure surface swirling channel 23 and the suction surface swirling channel 24, and finally flows out through the trailing edge slit 5. Figure 3 The arrows in the diagram indicate the direction of airflow for the cool air entering the blade tip cooling chamber 2.

[0032] This application supplies air separately to the blade tip cooling chamber 2 through the blade tip air supply channel 3, ensuring the amount of cold air and the low temperature in the blade tip region. The cold air entering the blade tip cooling chamber 2 first enters the annular partition wall 21, and then is accelerated through the impact throat 22 to impact the leading edge region of the blade tip cooling chamber 2. It is split in the leading edge region of the blade and forms a swirling flow in the suction surface swirling channel 24 and the pressure surface swirling channel 23. The swirling cold air in the suction surface swirling channel 24 and the pressure surface swirling channel 23 forms a double swirling cold air in the blade tip cooling chamber 2. The swirling cold air is discharged to the trailing edge region of the blade, realizing efficient cooling of the blade tip region and solving problems such as blade tip hot spots and ablation.

[0033] The specific design of the location and shape of the blade tip cooling chamber 2 is as follows:

[0034] In one embodiment, the profile of the annular spacer 21 facing the blade pressure surface and the profile of the inner wall of the blade tip cooling chamber 2 corresponding to the blade pressure surface maintain the same curvature change trend and contour direction. Similarly, the profile of the annular spacer 21 facing the blade suction surface and the profile of the inner wall of the blade tip cooling chamber 2 corresponding to the blade suction surface maintain the same curvature change trend and contour direction. The sidewalls of the annular spacer 21 facing the blade pressure surface and the sidewalls facing the blade suction surface are connected by an arc-shaped transition segment, which is circular.

[0035] At the same blade height, the curvature change trend and contour direction of the inner wall surface of the blade tip cooling chamber 2 and the outer wall surface of the blade are the same; at the same blade height, the middle arc line of the blade tip cooling chamber 2 is located on the middle arc line of the outer wall of the blade, and at the same blade height, the middle arc line of the annular partition wall 21 is located on the middle arc line of the blade tip cooling chamber 2, and the intersection point of the outer wall of the arc segment and the middle arc line of the blade tip cooling chamber 2 is the dividing point. The middle arc line of the dividing point and the leading edge point of the blade tip cooling chamber 2 accounts for 30-50% of the entire middle arc line length of the blade tip cooling chamber 2.

[0036] The maximum inscribed circle of the inner wall of the annular partition wall 21 and the maximum inscribed circle of the inner wall of the blade tip cooling chamber 2 are concentric.

[0037] The specific design of the internal structure of blade tip cooling chamber 2 is as follows:

[0038] The annular partition wall 21 is provided with a V-shaped rib 25 fixed to the partition plate 1. The V-shaped rib 25 is located between the communication position of the blade tip air supply channel 3 and the blade tip cooling chamber 2 and the leading edge of the blade. The concave surface of the V-shaped rib 25 faces the air outlet side of the blade tip air supply channel 3. In this embodiment, the V-shaped rib 25 and the inner top wall of the blade are spaced apart.

[0039] The annular partition wall 21 is provided with two V-shaped ribs 25. The two V-shaped ribs 25 are distributed sequentially along the middle arc line at the blade height position corresponding to the septum 1, and the tip of the V-shaped rib 25 near the leading edge faces the impact throat 22.

[0040] Multiple guide pin ribs 26 are provided in the blade tip cooling chamber 2 between the annular partition wall 21 and the blade trailing edge. The cross-section of the guide pin ribs 26 gradually decreases from the leading edge to the trailing edge of the blade. Specifically, multiple rows of guide pin ribs 26 are sequentially arranged in the blade tip cooling chamber 2 along the mid-arc line at the blade height position corresponding to the partition 1 between the annular partition wall 21 and the blade trailing edge, and the number of guide pin ribs 26 in each row gradually decreases from the trailing edge side of the annular partition wall 21 to the trailing edge side of the blade.

[0041] The blade has multiple pressure surface air film holes 27 that communicate with the blade tip cooling chamber 2 on its pressure surface, and suction surface air film holes 28 that communicate with the blade tip cooling chamber 2 on its suction surface.

[0042] The blade tip wall is provided with multiple blade tip dust removal holes 29 that communicate with the blade tip cooling chamber 2.

[0043] like Figure 3 As shown, the cold air entering the blade tip cooling chamber 2 first enters the annular partition wall 21, flows through the V-shaped ribs 25 inside the annular partition wall 21, and then accelerates through the impact throat 22 to impact the leading edge region of the blade tip cooling chamber 2. A double swirling flow is formed in the suction side swirling channel 24 and the pressure side swirling channel 23. Part of the cold air is discharged from the pressure side film cooling hole 27, the suction side film cooling hole 28, and the blade tip dust removal hole 29, forming a cooling film to protect against combustion gas intrusion. The other part of the cold air flows towards the trailing edge region of the blade tip cooling chamber 2, and after being turbulently enhanced by the guide pin ribs 26, it is discharged at the trailing edge slit 5. This further improves the efficient cooling of the blade tip region and solves problems such as blade tip hot spots and ablation.

[0044] like Figure 2 As shown, in one embodiment, the blade cooling chamber 4 is specifically as follows:

[0045] A first mid-chord cooling chamber 41 is provided in the area between the blade tip air supply channel 3 and the leading edge of the blade within the blade cooling chamber 4. A leading edge cooling chamber 43 is provided in the area between the first mid-chord cooling chamber 41 and the leading edge of the blade within the blade cooling chamber 4. One side of the leading edge cooling chamber 43 is connected to the first mid-chord cooling chamber 41 through an airflow hole. A second mid-chord cooling chamber 42 is provided in the area between the blade tip air supply channel 3 and the trailing edge of the blade within the blade cooling chamber 4. A trailing edge cooling chamber 44 is provided between the second mid-chord cooling chamber 42 and the trailing edge of the blade. One side of the trailing edge cooling chamber 44 is connected to the second mid-chord cooling chamber 42 through an airflow hole, and the other side of the trailing edge cooling chamber 44 is connected to the trailing edge slit 5. At the blade root, a first air supply chamber 45 is provided that connects to the first mid-chord cooling chamber 41 and a second air supply chamber 46 that connects to the second mid-chord cooling chamber 42. The first air supply chamber 45 and the second air supply chamber 46 form the blade air supply channel.

[0046] like Figure 2 As shown, cool air is supplied to the leading edge region, middle chord region, trailing edge region, and blade tip region of the blade through the first air supply chamber 45, the second air supply chamber 46, and the blade tip air supply channel 3, respectively; specifically, as shown... Figure 2 As indicated by the arrows showing the direction of the cold air flow, the cold air enters the first mid-chord cooling chamber 41 after passing through the first air supply chamber 45, and then enters the leading edge cooling chamber 43. The cold air then enters the second mid-chord cooling chamber 42 after passing through the second air supply chamber 46, and finally exits through the trailing edge slit 5. Individual cooling structures can also be installed on the first mid-chord cooling chamber 41, the second mid-chord cooling chamber 42, the leading edge cooling chamber 43, and the trailing edge cooling chamber 44 to adapt to the cooling needs of different areas. For example, the leading edge cooling chamber 43 can use impingement-film cooling; the first mid-chord cooling chamber 41 and the second mid-chord cooling chamber 42 can use ribbed multi-channel-film cooling; the trailing edge cooling chamber 44 can use turbulence-slit cooling; and the tip region can use the above cooling scheme, with each cooling chamber individually designed with enhanced cooling structures.

[0047] The above description is merely a specific embodiment of this application, but the scope of protection of this application 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 this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A turbine blade cooling structure for improving tip cooling capacity, characterized in that, The blade is hollow inside to form a cooling cavity. A partition (1) is provided on the side of the blade near the blade tip. The partition (1) divides the cavity into a blade tip cooling cavity (2) located between the partition (1) and the blade tip, and a blade body cooling cavity (4) located between the partition (1) and the blade root. The blade body cooling cavity (4) is provided with a blade tip air supply channel (3) that connects to the blade tip cooling cavity (2). The end of the blade tip air supply channel (3) away from the blade tip cooling cavity (2) extends to the blade root to connect to a cold air source. The blade is provided with a blade body air supply channel at the blade root that connects to the blade body cooling cavity (4). The blade body air supply channel connects to a cold air source. Both the blade body cooling cavity (4) and the blade tip cooling cavity (2) are provided with a trailing edge slit (5) on their trailing edge sides. Among them, an annular partition wall (21) is provided on the side of the blade tip cooling chamber (2) near the leading edge of the blade. One end of the annular partition wall (21) is integrally formed with the partition plate (1), and the other end of the annular partition wall (21) is integrally formed with the inner top wall of the blade. The outer wall of the annular partition wall (21) and the inner wall of the blade tip cooling chamber (2) are spaced apart. The side of the annular partition wall (21) near the leading edge of the blade has a notch to form an impact throat (22). A pressure surface swirling channel (23) is formed between the annular partition wall (21) and the inner wall of the blade tip cooling chamber (2) corresponding to the blade pressure surface. (21) and the blade tip cooling chamber (2) form a suction surface swirling channel (24) between the inner wall of the blade suction surface. The connection position of the blade tip air supply channel (3) and the blade tip cooling chamber (2) is located within the range of the annular partition wall (21). After the cold air entering the blade tip air supply channel (3) enters the annular partition wall (21), it impacts the inner wall of the leading edge of the blade tip cooling chamber (2) through the impact throat (22). The cold air impacting the inner wall of the leading edge of the blade tip cooling chamber (2) flows to the trailing edge of the blade tip cooling chamber (2) through the pressure surface swirling channel (23) and the suction surface swirling channel (24) respectively, and finally flows out through the trailing edge slit (5).

2. The turbine blade cooling structure for improving tip cooling capacity according to claim 1, characterized in that, The annular partition wall (21) facing the blade pressure surface and the inner wall of the blade tip cooling chamber (2) facing the blade pressure surface have the same curvature change trend and contour direction. The annular partition wall (21) facing the blade suction surface and the inner wall of the blade tip cooling chamber (2) facing the blade suction surface have the same curvature change trend and contour direction.

3. The turbine blade cooling structure for improving tip cooling capacity according to claim 2, characterized in that, The annular spacer (21) is connected by an arc-shaped transition between the sidewall facing the blade pressure surface and the sidewall facing the blade suction surface.

4. The turbine blade cooling structure for improving tip cooling capacity according to claim 3, characterized in that, The curvature change trend and contour direction of the inner wall surface of the blade tip cooling chamber (2) and the outer wall surface of the blade are the same at the same blade height position; At the same blade height, the middle arc of the blade tip cooling chamber (2) is located on the middle arc of the outer wall of the blade. At the same blade height, the middle arc of the annular partition wall (21) is located on the middle arc of the blade tip cooling chamber (2). The intersection of the outer wall of the arc segment and the middle arc of the blade tip cooling chamber (2) is the dividing point. The middle arc of the dividing point and the leading edge of the blade tip cooling chamber (2) accounts for 30-50% of the total length of the middle arc of the blade tip cooling chamber (2).

5. The turbine blade cooling structure for improving tip cooling capacity according to claim 4, characterized in that, The maximum inscribed circle of the inner wall of the annular partition wall (21) and the maximum inscribed circle of the inner wall of the blade tip cooling chamber (2) are concentric.

6. The turbine blade cooling structure for improving tip cooling capacity according to claim 1, characterized in that, The annular partition wall (21) is provided with a V-shaped rib (25) fixed on the partition plate (1). The V-shaped rib (25) is located between the connection position of the blade tip air supply channel (3) and the blade tip cooling chamber (2) and the leading edge of the blade. The concave surface of the V-shaped rib (25) faces the air outlet side of the blade tip air supply channel (3).

7. The turbine blade cooling structure for improving tip cooling capacity according to claim 6, characterized in that, The annular partition wall (21) is provided with two V-shaped ribs (25), which are distributed along the mid-arc line of the blade, and the tip of the V-shaped rib (25) near the leading edge faces the impact throat (22).

8. The turbine blade cooling structure for improving tip cooling capacity according to claim 1, characterized in that, The blade tip cooling chamber (2) is provided with multiple guide pin ribs (26) between the annular partition wall (21) and the blade trailing edge.

9. The turbine blade cooling structure for improving tip cooling capacity according to claim 1, characterized in that, The blade has multiple pressure surface air film holes (27) that communicate with the blade tip cooling chamber (2) on its pressure surface, and suction surface air film holes (28) that communicate with the blade tip cooling chamber (2) on its suction surface.

10. The turbine blade cooling structure for improving tip cooling capacity according to claim 1, characterized in that, Multiple blade tip dust removal holes (29) are provided on the blade tip wall surface, which are connected to the blade tip cooling chamber (2).

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