JP2002195003A - Moving blade tip cooling structure of gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving blade tip cooling structure of gas turbine, capable of cooling the tip parts of moving blades uniformly to a satisfactory degree. SOLUTION: A recess 91 is formed at the tip of the body part 90 of each moving blade, and a lid 100, having grooves 101, 102, 103 at the flank side face 100a, a rear-side face 100b and undersurface 100c, which are formed separately, is tightly attached to the recess. To the grooves, cooling air is fed from a cooling air lead-in passage 93i, formed at a front edge member 90f provided on the body and is exhausted from a cooling-air exhaust passage 93e formed at a trailing edge member 90r of the body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas turbine blade tip cooling structure.

[0002]

2. Description of the Related Art Gas turbines are widely used for power generation and various other purposes. This gas turbine injects fuel into air compressed to a high temperature by a compressor, burns it in a combustion cylinder to generate combustion gas, rectifies the combustion gas with stationary vanes, guides it to the moving blades, and rotates the turbine. The power is obtained at least. In order to increase the efficiency of the gas turbine, the temperature of the combustion gas guided to the moving blade should be as high as possible, and the temperature of the combustion gas falling on the moving blade tends to be higher.

[0003]

In order to realize such a high temperature of the combustion gas, it is necessary to improve the cooling of the moving blade so as to withstand the high temperature of the combustion gas. Here, the tip of the rotor blade is formed by assembling the belly-side member and the back-side member and sharpening them at one place in order to suppress the flow of the combustion gas from the ventral side to the dorsal side and increase the operating efficiency. Rather than preventing the inflow, the abdominal member and the backside member are each often configured to be close to the surrounding shroud provided on the casing side to prevent the inflow and to prevent the inflow, for example, There is a cooling structure described in JP-A-62-223402.

FIGS. 11A and 11B show a cooling structure disclosed in the above publication, in which cooling air is supplied to a blade tip and a lid of a blade formed along the blade cross-sectional shape. The cooling air flowing toward the slit is supplied through several supply holes from the axial center side.A space is provided between the supply hole and the slit. Although provided, the supply holes are not continuous and may not always be able to cool the wing tip portion sufficiently uniformly. In view of the above, an object of the present invention is to provide a moving blade tip cooling structure for a gas turbine that can sufficiently cool the tip of the moving blade.

[0005]

According to the first aspect of the present invention, the compressed air supplied from the compressor and the fuel injected from the fuel nozzle are burned in the combustion cylinder, and the combustion gas is guided to the moving blade. A blade tip cooling structure for cooling a blade tip of a moving blade using a part of compressed air of a gas turbine that obtains power, and has a depth in an axial direction from a blade tip surface of a moving blade body. A blade tip cooling air introduction passage passing through the inside of the leading edge member of the blade main body and having an outlet opening on the wall surface on the leading edge side of the concave portion, and an inlet opening on the wall surface on the trailing edge side of the concave portion; A blade tip cooling air discharge passage having an outlet opening at the trailing edge or near the trailing edge, which passes through the inside of the trailing edge member of the main body, is formed separately from the moving blade main body, and is tightly joined and fixed to the inner wall of the recess. With a lid member, which is in close contact with the inner wall of the concave portion of the lid member,
A blade cooling structure for a gas turbine is provided, wherein a plurality of grooves communicating the outlet opening of the blade tip cooling air introduction passage and the inlet opening of the blade tip cooling air discharge passage are provided. In the moving blade cooling structure of the gas turbine configured as described above, the cooling air flows through the plurality of grooves provided on the surface of the lid member that is in close contact with the inner wall of the concave portion, so that the blade tip can be uniformly cooled. .

According to a second aspect of the present invention, in the first aspect of the present invention, the concave portion has a front edge side wall surface, a rear edge side wall surface, an abdominal side wall surface, a back side wall surface, and a bottom surface, and the lid member is in front of the concave portion. It has front, rear, belly, back, and bottom surfaces that are in close contact with the edge side wall, rear edge side wall, ventral side wall, back side wall, and bottom surface, respectively, and the blade tip cooling air introduction passage has an outlet opening in the front edge side wall surface. The blade tip cooling air discharge passage has an inlet opening on a trailing edge side wall surface, and a groove is provided on at least one of a ventral side surface, a back side surface, and a lower surface of the lid member. Provided.

According to a third aspect of the present invention, there is provided the gas turbine bucket tip cooling structure according to the first aspect of the present invention, in which the grooves meander. In the gas turbine blade tip cooling structure configured as described above, the cooling air flows in a meandering manner, and the area that the cooling air hits increases. According to the fourth aspect of the present invention, the gas turbine moving blade tip cooling structure according to the first aspect, wherein a projection is formed on a surface of the groove. Claim 5
According to the invention of claim 1, in the invention of claim 1, a plurality of adjacent crank grooves are formed by connecting the first partial groove and the second partial groove whose grooves are displaced in the spanwise direction with a connection groove that is substantially perpendicular thereto. The first partial groove and the second partial groove of the crank groove are arranged so as to partially overlap in the spanwise direction, and the first partial groove and the second partial groove of the overlapped adjacent crank grooves are arranged.
A gas turbine blade tip cooling structure formed by connecting partial grooves with a communication passage is provided. In the blade cooling structure of the gas turbine configured as described above, the cooling air that has passed through the communication passage further impinges and cools the wall surface of the partial groove on the outlet side of the communication passage.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the gas groove and the communication passage are provided so that the cooling air flows from the axial center toward the blade tip. A turbine blade tip cooling structure is provided. In the moving blade cooling structure of the gas turbine configured as described above, the cooling air flows through the communication passage to the blade tip side, and can impinge cool the wall surface of the partial groove near the blade tip.

According to a seventh aspect of the present invention, there is provided the gas turbine blade tip cooling structure according to the first aspect of the invention, wherein the cross-sectional shape of the groove is any one of a square, a semicircle, and a triangle.

According to an eighth aspect of the present invention, there is provided the gas turbine blade tip cooling structure according to the first aspect, wherein the tip cooling air discharge passage has an outlet opening on a ventral surface near the trailing edge. . In the moving blade cooling structure of the gas turbine configured as described above, the cooling air that has exited the blade tip cooling air discharge passage performs film cooling from the abdomen to the back near the trailing edge. According to the ninth aspect of the present invention, there is provided the gas turbine blade tip cooling structure according to the first aspect of the present invention, wherein a groove extending from the leading edge side to the trailing edge side is formed on the outer surface of the lid member.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a basic structure of a peripheral portion of a combustor of a gas turbine to which the present invention is applied will be described with reference to FIG. A combustor 3 is disposed in a casing 2 formed by a casing 1, and high-temperature air compressed by a compressor 4 (only a part is shown) is indicated by an arrow 50 in the casing 2. To be introduced. The combustor 3 includes a combustion tube 6 that burns fuel and air to generate combustion gas, and an introduction unit 5 that guides the fuel and air to the combustion tube 6 to the combustion tube 6. A stator blade 8 is connected to the stationary blade 8 via a seal 7, and a moving blade 9 is disposed downstream of the stationary blade 8.

The introduction section 5 is configured by arranging one pilot nozzle 11 and a plurality of main nozzles 12 inside the inner cylinder 10. The high-temperature compressed air introduced into the passenger compartment 2 from the compressor 4 passes around the inner cylinder 10 toward the upstream side as indicated by an arrow 51, and the combustion air formed at the upstream end of the inner cylinder 10 It is introduced from the inlet 13 into the inner cylinder 10 as shown by an arrow 52. The air introduced into the inner cylinder 10 is turned into swirl air in a swirl flow path 15 having a plurality of swirlers 14, and then the fuel injected from the main nozzle 12 is mixed to form a premixed air. To the combustion tube 6.

The air introduced into the inner cylinder 10 passes through an air passage 11a around the pilot nozzle 11,
Downstream of the pilot nozzle 11, the fuel is diffused and burned together with the fuel injected from the pilot nozzle 11 to generate a pilot flame. This pilot flame is swirl channel 15
And ignites the premixed gas discharged from the combustion chamber. The tip 16 of the pilot nozzle 11 is disposed in a pilot cone 17 that spreads in a megaphone shape.

Hereinafter, a gas turbine moving blade cooling structure of the present invention applied to the above-described gas turbine will be described by taking as an example a case where the present invention is applied to a moving blade. FIG. 1 is an exploded view showing a first embodiment of a gas turbine blade cooling structure according to the present invention. A concave portion 91 is formed in the blade end surface of the main body 90 of the moving blade 9, and the lid member 100 is fitted into the concave portion and fixed by welding or the like to complete the operation.

The concave portion 91 has a leading edge side wall surface 91f, a trailing edge side wall surface 91r, and a ventral side wall surface 91a having the same depth from the blade tip surface.
It has a back side wall surface 91b and a bottom surface 91c, and has a front edge side wall surface 91f.
And the trailing edge side wall surface 91r extends straight in the direction perpendicular to the blade width direction, that is, in the blade thickness direction.
1a and the back side wall surface 91b extend in the spanwise direction while covering in parallel with the abdominal surface 92a and the back side surface 92b, respectively. The bottom surface 91c has the same shape as the shape of the opening on the wing tip side.

Of the members forming the main body 90, the portion on the front side of the (rear edge side wall surface 91f) of the concave portion 91 is the front edge member 90f, and the portion on the rear side of the concave portion 91 (rear edge side wall surface 91r). The rear edge member 90r and the member between the abdominal wall surface 91a and the abdominal surface 92a of the concave portion 91 are replaced with the abdominal member 90a and the concave portion 91.
The member between the back wall surface 91b and the back surface 92b is referred to as a back member 90b. The member on which the bottom surface 91c is formed is referred to as a concave bottom surface member 90c. The leading edge member 90
f, trailing edge member 90r, abdominal member 90a, dorsal member 90b
Includes not only the portion around the concave portion 91 but also from the blade tip to the axial center end (not shown).

A tip cooling air introduction passage 93i is formed in the leading edge member 90f, and a tip cooling air discharge passage 93e is formed in the trailing edge member 90r. As apparent from FIGS. 2 and 3, the blade tip cooling air introduction passage 93i extends to the axial center side, and is connected to a cooling air introduction passage formed in a shaft member (not shown) at an axial end (not shown). Have been. Further, the blade tip cooling air discharge passage 93e is located near the trailing edge,
At an intermediate position in the blade length direction of the concave portion 91, an outlet opening 95e is provided in the ventral surface 92a, and the cooling air flowing out of the outlet opening 95e has a wing tip portion from the ventral surface 92a toward the back surface 92b. Cool the film.

Further, three central cooling air passages 93a, 93b, 93c are formed on the axial center side of the bottom member 90c, and the cooling air is introduced from a cooling air introducing passage formed in a shaft member (not shown). Air is introduced and the ventral member 90
a, the film is discharged from a hole (not shown) formed in the back member 90b, and the ventral surface 92a and the back surface 92b are film-cooled.

On the other hand, the lid member 100 is
1 front edge side wall surface 91f, rear edge side wall surface 91r, abdominal wall surface 9
1a, front side 100f, rear side 100r, and ventral side 100, which are in close contact with the back side wall surface 91b and the bottom surface 91c, respectively.
a, a back surface 100b, a lower surface 100c, and an outer upper surface 100d.

The front surface 100f and the rear surface 100 of the lid member 100
r is a plane, but two grooves 101 each having a rectangular cross section are formed on the ventral side surface 100a and the back side surface 100b. Also, grooves 102 having the same cross section as the above-mentioned grooves 101 are formed on the lower surface 100c. There are three grooves 102 at the leading edge, but they are gathered at the trailing edge because the size in the blade thickness direction becomes smaller. On the other hand, a large groove 10 is formed on the upper surface 100d.
Only one 3 is formed.

As shown in FIG.
The opening 94 of the blade tip cooling air introduction passage 93i is positioned such that the leading edge side ends of the grooves 101 and 102 are within the area of the outlet opening 94i of the blade tip cooling air introduction passage 93i.
The shape of i is determined. Similarly, grooves 101 and 102
The trailing edge side end is the opening 94 of the blade tip cooling air discharge passage 93e.
Although the shape of the opening 94e at the inlet of the blade tip cooling air discharge passage 93e is determined so as to be within the region e, it is not shown.

The first embodiment is configured as described above, and the cooling air passing through the blade tip cooling air introduction passage 93i flows through the groove 101 of the lid member, the abdominal wall surface 91a, and the back wall surface 91b. Passage formed, groove 102 and bottom surface 91
c, and then discharged through a blade tip cooling air discharge passage 93e. Therefore, the lid member 1
00 is continuously cooled from the leading edge side to the trailing edge side.

The cross-sectional shape of the groove can be appropriately changed. For example, a semicircular shape as shown in FIG.
A triangle as shown in FIG.

Next, a second embodiment will be described. In the second embodiment, the lid member 200 is different from the lid member 100 of the first embodiment, but the main body 90 is the same. Therefore, only the lid member 200 will be described. FIG. 6 is a view of the lid member 200 according to the second embodiment as viewed from the ventral side. On the ventral side of the lid member 200, an inner groove 210 and an outer groove 220 shifted in the wing width direction are radially grooved. A crank groove 201 connected by 230 is formed. The same applies to the back side. The second embodiment is configured as described above, and as shown by arrows in FIG. 6, the cooling air meanders and flows, and the lid member 200 can be continuously cooled in the spanwise direction. Efficient.

Next, a modification of the second embodiment will be described with reference to FIG. In this modification, a large number of protrusions 240 are provided on the surface of the meandering groove of the second embodiment. With this configuration, the turbulence of the flow of the cooling air is increased, and the cooling performance is further improved. In addition,
Such a protrusion can be applied to the first embodiment and a third embodiment described later.

Next, a third embodiment will be described. In the third embodiment, the lid member 300 is different from the lid member 100 of the first embodiment, but the main body 90 is the same. Therefore, only the lid member 300 will be described. FIG. 8 is a view of the lid member 300 according to the third embodiment as viewed from the ventral side. In the ventral side surface 300a of the lid member 300, an inner groove 310 and an outer groove 320 shifted in the wing width direction are provided in a radial direction. A plurality of crank grooves 301 connected by grooves 330 are formed, and inner grooves 310 and outer grooves 320 of adjacent crank grooves 301 are formed.
Are communicated through the communication hole 340. In FIG. 8, the front 30
0f has an intermediate portion of the outer groove 320, and the rear surface 300r has an intermediate portion of the outer groove 320. The communication hole 340 is provided on the front surface 300f and the rear surface 300r. Other parts may be provided on the front surface 300f and the rear surface 300r only if they do not come.

FIG. 9A is a view taken along the line IXA-IXA in FIG. 8, FIG. 9B is a view taken along the line IXB-IXB in FIG. 8, and FIG. 8 is taken along the line IXC-IXC, and (D) is taken along the line IXD-IXD in FIG. The third embodiment is configured as described above, and as shown by the arrow in FIG. 8, the cooling air flows, and the lid member 300 can be continuously cooled in the spanwise direction. Since the air passing through cools the upper (outer) surface of the groove by impingement cooling, the cooling efficiency is high.

As is apparent from the respective drawings in FIG. 8, the back side surface 300b is formed in the same manner as the ventral side surface 300a. Then, the lower surface 300c and the upper surface 300 of the lid member 300
d is the lower surface 100 of the lid member 100 of the first embodiment.
c, the same as the upper surface 100d, and the grooves 302, 303
Are formed.

As described above, the first embodiment, the second embodiment (including modified examples), and the third embodiment have been described. In all of these, the concave portion has the front edge side wall surface and the rear edge side wall surface. Front surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, rear surface, and rear surface. , And a lower surface. However, having such a distinct surface is not necessary,
The concave portion may have a bathtub shape formed of a continuous curved surface, and the lid member may have a curved surface that is in close contact with the bathtub. The blade tip surface of the rotor blade has a slightly raised portion in the center in the blade thickness direction so as to be in contact with the surface of a casing disposed around the blade via a uniform gap.

[0030]

According to the invention described in each claim, the compressed air supplied from the compressor and the fuel injected from the fuel nozzle are burned in the combustion cylinder, and the combustion gas is guided to the rotor blade to obtain power. A turbine blade tip cooling structure that cools a blade tip of a rotor blade using a part of compressed air of a turbine, but has a recess formed with a depth in an axial direction from a blade tip surface of the rotor blade body. A blade tip cooling air introduction passage passing through the inside of the leading edge member of the rotor blade body and having an outlet opening on the wall surface on the leading edge side of the concave portion; and an inlet opening on the wall surface on the trailing edge side of the concave portion; Through the inside of the member,
A blade tip cooling air discharge passage having an outlet opening at a trailing edge or a blade surface near the trailing edge; and a lid member formed separately from the rotor blade body and tightly joined and fixed to the inner wall of the concave portion. A plurality of grooves communicating with an outlet opening of the blade tip cooling air introduction passage and an inlet opening of the blade tip cooling air discharge passage are provided on a surface of the member that is in close contact with the inner wall of the concave portion, and is closely joined to the inner wall of the concave portion of the lid member. Since the cooling air flows through the plurality of grooves provided on the surface to be cooled, the blade tip can be uniformly cooled. In particular, if the groove is meandered as in claim 3, the cooling air meanders and flows, and the area where the cooling air hits increases, thereby improving the cooling performance.
In particular, if a protrusion is provided on the surface of the groove as in claim 4,
The turbulence of the cooling air increases and the cooling performance improves. In particular,
A plurality of crank grooves formed by connecting a first partial groove and a second partial groove whose grooves are displaced in the spanwise direction with a connection groove substantially perpendicular thereto as in claim 5, wherein a plurality of first grooves of adjacent crank grooves are provided. The groove and the second partial groove are arranged so as to partially overlap each other in the spanwise direction, and the first and second partial grooves of the overlapped adjacent crank grooves are connected by a communication passage. For example, the cooling air that has passed through the communication passage can impinge cool the wall surface of the partial groove on the outlet side of the communication passage, thereby improving the cooling efficiency. Further, if the crank groove and the communication path are provided so that the cooling air flows from the axial center side toward the blade tip side, the cooling air flows through the communication path to the blade tip side, Impingement cooling can be performed on the wall surface of the partial groove near the blade tip, and cooling on the blade tip side is improved.

[Brief description of the drawings]

FIG. 1 is an exploded view showing a gas turbine blade cooling structure of the present invention.

FIG. 2 is a cross-sectional view taken along a plane passing through line II-II of FIG.

FIG. 3 is a view showing a moving blade in a blade length direction in a state where a lid member is mounted, wherein FIG.
2B is a sectional view taken along the line IIIB-IIIB in FIG. 2, FIG. 2C is a sectional view taken along the line IIIC-IIIC in FIG. 2, and FIG. It is sectional drawing seen along the -IIID line.

FIG. 4 is a view taken along line IV-IV in FIG. 2;

5A and 5B are views showing a modification of a groove formed in a lid member, wherein FIG. 5A shows a semi-circular cross section and FIG. 5B shows a triangular cross section.

FIG. 6 is a side view of a lid member according to a second embodiment.

FIG. 7 is a side view of a lid member according to a modification of the second embodiment.

FIG. 8 is a side view of a lid member according to a third embodiment.

FIG. 9 is a cross-sectional view of the lid member of FIG.
FIG. 8B is a view taken along the line IXA-IXA of FIG.
FIG. 8C is a view taken along the line IXB-IXB, and FIG.
FIG. 8D is a view taken along the line C-IXC, and FIG.
Seen along the IXD line.

FIG. 10 is a diagram showing a structure around a combustor of the gas turbine.

11A and 11B are views showing a blade cooling structure of a conventional gas turbine, wherein FIG. 11A is a view seen from the blade tip side, and FIG. 11B is a view seen along the line XIB-XIB of FIG. FIG.

[Explanation of symbols]

 9: moving blade 90: (moving blade) main body 90a: abdominal member 90b ... dorsal member 90f: leading edge member 90r ... trailing edge member 91: concave portion 91a: abdominal wall surface (of the concave portion) 91b: (back of the concave portion) Side wall surface 91c ... Bottom surface (of concave portion) 91f ... Front edge side wall surface (of concave portion) 91r ... Rear edge side wall surface (of concave portion) 92a ... Ventral surface 92b ... Back surface 93i ... Cooling air introduction passage 93e ... Cooling air discharge passage 94i .. Outlet opening (of the cooling air introduction passage) 94e. Inlet opening (of the cooling air discharge passage) 95e. Outlet opening (of the cooling air discharge passage). 100. lid member 101, 102, 103 .. groove 100a. Side 100b ... (lid member) Back side 100c ... (lid member) bottom surface 100d ... (lid member) top surface 100f ... (lid member) front surface 100r ... (lid member) rear surface 200 ... lid member 201 ... groove 210 ... inside Groove 220: Outer groove 230: Radial groove 300: Lid member 201, 202, 203: Groove 300a: (Lid member) Ventral surface 300b: (Lid member) Back surface 300c: (Lid member) Bottom surface 300d: (Lid member) Upper surface 300f Front surface (cover member) 300r Rear surface (cover member) 310 Inner groove 320 Outer groove 330 Radial groove 340 Communication hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuo Ishiguro 2-1-1 Shinama, Arai-machi, Takasago City, Hyogo Prefecture Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Masaaki Matsuura 2-1-1, Araimachi Shinama, Takasago-shi, Hyogo Prefecture No. 1 Inside Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Kunihiro Shimizu 1200, Higashi-Tanaka, Komaki, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Nagoya Guidance Propulsion System Works F-term (reference) 3G002 CA05 CA06 CA07 CA08 CB04

Claims (9)

[Claims] 1. A part of compressed air of a gas turbine which burns compressed air supplied from a compressor and fuel injected from a fuel nozzle in a combustion cylinder and guides the combustion gas to a moving blade to obtain power. A blade tip cooling structure for cooling a blade tip of a rotor blade using the same, comprising a recess formed to have a depth in an axial direction from a blade tip surface of the rotor blade body, and a leading edge member of the rotor blade body. A blade tip cooling air introduction passage passing through the inside and having an outlet opening on the leading edge side wall of the concave portion, and having an inlet opening on the trailing edge side wall surface of the concave portion, passing through the inside of the trailing edge member of the moving blade body, and leading or trailing A blade tip cooling air discharge passage having an outlet opening on the blade surface near the edge; and a lid member formed separately from the rotor blade body and tightly joined and fixed to the inner wall of the concave portion, the inner wall of the concave portion of the lid member The outlet opening of the blade tip cooling air inlet passage and the inlet of the blade tip cooling air discharge passage Gas turbine rotor assembly end cooling structure in which a plurality of grooves for communicating the mouth is provided, that said. 2. The concave portion has a front edge side wall surface, a rear edge side wall surface, a ventral side wall surface, a rear side wall surface, and a bottom surface, and the lid member has a front edge side wall surface, a rear edge side wall surface, a ventral side wall surface of the concave portion,
The front-side, rear-side, belly-side, back-side, and bottom-side surfaces are in close contact with the rear-side wall and the bottom, respectively. 2. The gas turbine blade tip cooling structure according to claim 1, wherein the wall has an inlet opening, and the groove is provided on at least one of an abdominal surface, a back surface, and a lower surface of the lid member. 3. 3. The gas turbine blade tip cooling structure according to claim 1, wherein the groove is meandering. 4. The gas turbine blade tip cooling structure according to claim 1, wherein a projection is formed on a surface of the groove. 5. A first partial groove in which grooves are shifted in a spanwise direction and a second partial groove.
A plurality of crank grooves, which are formed by connecting the partial grooves with connection grooves that are substantially perpendicular thereto, are formed by a plurality of first and second adjacent groove grooves.
The partial grooves are arranged so as to partially overlap each other in the spanwise direction, and the first and second partial grooves of the overlapped adjacent crank grooves are connected by a communication passage. The gas turbine bucket tip cooling structure according to claim 1, characterized in that: 6. The gas turbine rotor blade according to claim 3, wherein the crank groove and the communication passage are arranged so that the cooling air flows from the axial center side toward the blade tip side. Edge cooling structure. 7. The gas turbine blade tip cooling structure according to claim 1, wherein the cross-sectional shape of the groove is any one of a square, a semicircle, and a triangle. 8. The wing tip cooling air discharge passage has an outlet opening on a ventral surface near a trailing edge.
2. The gas turbine blade tip cooling structure according to item 1. 9. The cover member according to claim 1, wherein a groove extending from a front edge side to a rear edge side is formed on an outer surface of the lid member.
2. The gas turbine blade tip cooling structure according to item 1.