JP2010236487A - Turbine blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce peeling and pressure loss in a U-turn part of a serpentine flow passage and to improve cooling performance. <P>SOLUTION: This turbine blade includes a semi-circular part 35 at a tip end of a partitioning wall 32 partitioning a cooling passage 6a positioned further upstream of the U-turn part 17 of the serpentine flow passage and a cooling passage 6b positioned downstream and projecting toward the U-turn part 17, and an expansion part 34 projecting toward the inside of the cooling passage 6b positioned downstream and having a linear part 36 for gradually increasing a flow passage cross sectional area and the flow passage width of the cooling passage 6b positioned downstream. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gas turbine, and more particularly to a turbine blade (moving blade / static blade) of a gas turbine.

  As a turbine blade of a gas turbine, for example, one disclosed in Patent Document 1 is known.

JP 2001-271603 A

A serpentine flow path is employed in the cooling passage of the turbine blade disclosed in Patent Document 1 from the viewpoint of improving the cooling performance.
However, in the U-turn part (reversal part) of the serpentine flow path, the vicinity of the surface forming the downstream cooling passage at the tip of the partition wall that partitions the upstream cooling passage and the downstream cooling passage, and the U-turn The fluid (cooling medium) is peeled off at the corners (corner portions), increasing the pressure loss and reducing the cooling performance.

  The present invention has been made in view of the above circumstances, and provides a turbine blade that can reduce peeling and pressure loss in a U-turn portion of a serpentine flow path and can improve cooling performance. Objective.

The present invention employs the following means in order to solve the above problems.
A turbine blade according to the present invention is a turbine blade having a serpentine flow path that guides a cooling medium supplied from a blade root portion to the inside of the blade, and is located upstream of a U-turn portion of the serpentine flow path. And a semicircular portion projecting toward the U-turn portion, and projecting into the cooling passage located on the downstream side, at the tip of the partition wall that partitions the cooling passage and the cooling passage located on the downstream side, A bulging portion having a flow passage cross-sectional area of the cooling passage located on the downstream side and a linear portion that gradually increases the flow passage width is provided.

  According to the turbine blade according to the present invention, the cooling medium flowing along the partition through the cooling passage located on the upstream side of the U-turn portion is like the partition of a conventional turbine blade not provided with the bulging portion. Without being suddenly turned around, it is guided by the surface of the semicircular part and the straight part (along the surface of the semicircular part and the linear part) and smoothly flows into the cooling passage located downstream of the U-turn part. Therefore, peeling and pressure loss in the U-turn portion can be reduced, and cooling performance can be improved.

In the turbine blade, an angle formed between a surface of the partition wall that forms a cooling passage located downstream of the straight portion and a surface of the straight portion is set within a range of 5 degrees to 10 degrees. It is more preferable that the value obtained by dividing the radius of the semicircular portion by the thickness of the portion of the partition wall not including the bulging portion is set within a range of 1 to 3.
Further, in the turbine blade, an angle formed between a surface of the partition wall forming a cooling passage located downstream of the straight portion and a surface of the straight portion is set to 10 degrees, and the semicircular portion It is more preferable that the value obtained by dividing the radius by the plate thickness of the portion not including the bulging portion of the partition wall is set to 1.
Further, in the turbine blade, an angle formed between a surface of the partition wall forming a cooling passage located downstream of the straight portion and a surface of the straight portion is set to 5 degrees, and the semicircular portion It is more preferable that the value obtained by dividing the radius by the thickness of the portion of the partition wall not including the bulging portion is set within a range of 2 to 3.

  According to such a turbine blade, separation and pressure loss in the U-turn portion can be further reduced, and the cooling performance can be further improved.

  In the turbine blade, it is more preferable that a concave portion having an arc shape in a sectional view is provided on a surface of the partition wall, which is located on the back side of the straight portion and forms a cooling passage located on the upstream side. is there.

  According to such a turbine blade, since the increase in the wall thickness of the partition wall due to the provision of the bulging portion can be minimized, the heat capacity of the bulging portion can be reduced, and the bulging portion is provided. The generation of hot spots due to can be reduced. In addition, the necessity of increasing the amount of the cooling medium for cooling the hot spot is reduced, and the cooling performance can be further improved.

  In the turbine blade, the cooling passage located on the upstream side and the cooling passage located on the downstream side through the partition wall are communicated with each other to form a cooling passage located on the upstream side of the partition wall. At least one first communication path having a first opening and having a second opening on a surface of the linear portion, wherein the first opening is closer to the blade tip than the second opening; It is more preferable that it is located.

  According to such a turbine blade, the first opening located at one end of the first communication path is closer to the blade tip than the second opening located at the other end of the first communication path. The cooling effect of the cooling medium flowing along the surface of the straight portion having the second opening is formed by the pumping effect generated by the centrifugal force from the blade root to the blade tip direction, which is caused by the rotation of the blade. A part flows through the first communication path, that is, from the second opening to the first communication path, passes through the first communication path, and then flows out from the first opening to the upstream side. Since it is guided (sucked out) into the cooling passage located, peeling and pressure loss in the U-turn portion can be further reduced, and the cooling performance can be further improved.

  In the turbine blade, it is more preferable that at least one dimple is provided on the surface of the semicircular portion and the straight portion.

  According to such a turbine blade, separation and pressure loss in the U-turn portion can be further reduced, and the cooling performance can be further improved.

  In the turbine blade, two or more serpentine flow paths are provided, and one serpentine flow path and the other serpentine flow path are provided at a tip portion of a rib partitioning one serpentine flow path and the other serpentine flow path adjacent to each other. It is more preferable that at least one second communication path that communicates with each other is provided.

  According to such a turbine blade, at one end of the rib, that is, at a corner (corner) of the U-turn portion, from one serpentine channel to the other serpentine channel or from the other serpentine channel. Since the flow of the cooling medium to the serpentine flow path is formed through the second communication path, the generation of hot spots at the corners of the U-turn portion can be reduced and the hot spots can be cooled. Therefore, the necessity for increasing the amount of the cooling medium is reduced, and the cooling performance can be further improved. Further, peeling and pressure loss at the corners of the U-turn portion can be further reduced, and the cooling performance can be further improved.

  The gas turbine according to the present invention includes turbine blades that can reduce separation and pressure loss in the U-turn portion of the serpentine flow path and can improve cooling performance.

According to the gas turbine of the present invention, the amount of cooling air flowing into the cooling passage can be reduced by improving the cooling performance of the turbine blades, and the performance of the gas turbine can be improved.
In addition, in the type of gas turbine that collects the cooling medium (steam, etc.) that has passed through the turbine blades and cooled the turbine blades, the combined cycle efficiency is improved by reducing the pressure loss in the turbine blades. Will do.

  According to the turbine blade according to the present invention, it is possible to reduce peeling and pressure loss in the U-turn portion of the serpentine flow path, and it is possible to improve the cooling performance.

It is a longitudinal cross-sectional view of the blade for turbines concerning 1st Embodiment of this invention. It is the figure which expanded the principal part of FIG. It is the figure which expanded the principal part of FIG. 1, Comprising: It is a figure similar to FIG. It is a graph which shows the result of the experiment conducted using the turbine blade | wing which concerns on 1st Embodiment of this invention. It is the figure which expanded the principal part of the blade for turbines concerning 2nd Embodiment of this invention, Comprising: It is a figure similar to FIG. 2 and FIG. It is the figure which expanded the principal part of the blade for turbines concerning 3rd Embodiment of this invention, Comprising: It is a figure similar to FIG. 2 and FIG. It is the figure which expanded the principal part of the blade for turbines concerning 4th Embodiment of this invention, Comprising: It is a figure similar to FIG. 2 and FIG. It is the figure which expanded the principal part of the blade for turbines concerning 5th Embodiment of this invention, Comprising: It is a figure similar to FIG. 2 and FIG.

Hereinafter, a first embodiment of a turbine blade according to the present invention will be described with reference to FIGS. 1 to 4.
1 is a longitudinal sectional view of a turbine blade according to the present embodiment, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. 3 is an enlarged view of the main part of FIG. FIG. 4 and FIG. 4 are tables showing the results of experiments conducted using the turbine blades according to the present embodiment.

  The turbine blade 1 according to the present embodiment includes, for example, a compression section (not shown) that compresses combustion air, and injects and burns fuel into high-pressure air sent from the compression section to perform high-temperature combustion. A gas composed mainly of a combustion section (not shown) that generates gas and a turbine section (not shown) that is located on the downstream side of the combustion section and is driven by the combustion gas exiting the combustion section The turbine can be applied to a moving blade (for example, a one-stage moving blade) in a turbine section.

  In FIG. 1, reference numeral 2 denotes a blade root portion, and 3 denotes a platform. Inside the turbine blade 1, a cooling passage 4a and a serpentine cooling passage including cooling passages 5a, 5b, 5c, 6a, 6b, and 6c are formed. The blade root 2 is provided with cooling passages 4, 5, 6, and 7 independently. The cooling passage 4 is located on the leading edge side (left side in FIG. 1) and communicates with the cooling passage 4a in the blade. Cooling air 10 flows into the cooling passage 4 from the rotor side, cools the leading edge of the blade in the process of passing through the cooling passage 4a, and then flows out of the cooling hole 19 to cool the leading edge of the shower head film. The cooling air 11 flows into the cooling passage 5, passes through the cooling passage 5 a in the blade, turns 180 ° at the U-turn portion 15 on the turbine outer diameter side (upper side in FIG. 1), and flows into the cooling passage 5 b. Then, the U-turn part 16 on the turbine inner diameter side (downward in FIG. 1) turns upward again to flow into the cooling passage 5c, and flows out from the blade tip. In this process, the film is cooled by flowing out from the cooling hole (not shown) to the blade surface.

  The cooling air 12 flows into the cooling passage 6 and the cooling air 13 flows into the cooling passage 7 and merges to flow through the cooling passage 6a. Then, after turning 180 ° at the U-turn portion 17 on the outer diameter side, it enters the cooling passage 6b and then turns upward again at the U-turn portion 18 on the inner diameter side and flows into the cooling flow path 6c. In this process, the film is cooled by flowing out from the cooling hole (not shown) to the blade surface, and the remaining air flows out from the discharge hole 21 after the pin fin cooling is performed in the region reaching the blade trailing edge 20.

Now, in the turbine blade 1 according to the present embodiment, the tip (part on the blade tip side) of the partition wall (partition wall) 31 that partitions the cooling passage 5a and the cooling passage 5b, and the cooling passage 6a and the cooling passage 6b. Swelling portions 33 and 34 are provided at the tip end portion (end portion on the blade tip side) of the partition wall (partition wall) 32.
As shown in FIG. 1, the bulging portion 33 is a bulge that protrudes toward the U-turn portion 15 and also protrudes into the cooling passage 5 b located on the downstream side. The bulge protrudes toward the portion 17 and protrudes into the cooling passage 6b located on the downstream side.
Since the bulging portion 33 and the bulging portion 34 are composed of the same components that are symmetrical in FIG. 1, only the bulging portion 34 will be described below.

As shown in FIG. 2, the bulging portion 34 includes a semicircular portion 35 that protrudes toward the U-turn portion 17 and a linear portion 36 that protrudes into the cooling passage 6 b located on the downstream side. .
The upstream end of the semicircular portion 35 is connected to the downstream end of the one surface 32a of the partition wall 32 facing the cooling passage 6a, and the downstream end of the semicircular portion 35 is connected to the upstream end of the straight portion 36, The downstream end of 36 is connected to the upstream end of the other surface 32b of the partition wall 32 that faces the cooling passage 6b.

The semicircular portion 35 and the straight portion 36 are formed so as to satisfy the formula of 5 degrees ≦ θ ≦ 10 degrees and the formula of 1 ≦ R / T ≦ 3. Here, θ is an angle (inclination angle) formed between the other surface 32b of the partition wall 32 and the surface of the linear portion 36, R is a radius of the semicircular portion 35, and T is a plate thickness of the partition wall 32 (one surface 32a and the other surface 32b). Distance).
Further, the semicircular portion 35 and the straight portion _{36, A 2 / A 1 = 0.4~1.8} , A 3 / A 1 = 0.4~1.0, L 2 / L 1 = 1.0~ 1.5, and L ₃ / L ₁ = 0.6 to 1.0. Here, A ₁ and L ₁ are the channel cross-sectional area and the channel width at the location indicated by reference numeral 101 in FIG. 3 (the distance between the upstream end of the semicircular portion 35 and the surface 37 facing the upstream end). ), A ₂ and L ₂ are the channel cross-sectional area and the channel width (the distance between the apex of the semicircular portion 35 and the surface 38 facing this apex) at the location indicated by reference numeral 102 in FIG. ₃ and L ₃ are the channel cross-sectional area and the channel width (the distance between the downstream end of the semicircular portion 35 and the surface 39 facing the downstream end) at the location indicated by reference numeral 103 in FIG.

_{Then, A 2 / A 1 = 1.0} , A 3 / A 1 = 0.7~1.0, L 2 / L 1 = 1.0, and L 3 / L 1 = 0.7~1.0 and , Θ = 5 °, pressure loss coefficient when R / T = 1, 2, 3 and A ₂ / A ₁ = 1.0, A ₃ / A ₁ = 0.7 to 1.0, L ₂ / L ₁ = 1.0, L ₃ / L ₁ = 0.7 to 1.0, θ = 10 °, and the pressure loss coefficient when R / T = 1, 2, 3 is experimentally determined. The experimental result shown in FIG. 4 was obtained. Note that the “base case” shown in FIG. 4 is a conventional turbine blade (R / T = 1.0) that does not include the bulging portion 34 including the semicircular portion 35 and the straight portion 36 according to the present embodiment. ), And FIG. 4 shows each experimental result as a relative value when the pressure loss coefficient of this base case is 1.0.
From FIG. 4, when θ = 5 ° and R / T = 2, the pressure loss coefficient becomes the smallest. When R / T = 2, 3, that is, when R of the semicircular portion 35 is large, θ is reduced. It can be seen that the pressure loss coefficient is small.
Here, the pressure loss coefficient can be expressed by ΔP / ((1/2) × ρ × V ² ). ΔP is the pressure P ₁ (see FIG. 3) of the fluid (room temperature air in this experiment) passing between the upstream end of the semicircular portion 35 and the surface 37 facing the upstream end, and the straight portion. The difference (P ₁ ) between the pressure P ₂ (see FIG. 3) of the fluid passing between the other surface 32b of the partition wall 32 located on the downstream side of the downstream end of 36 and the surface 39 facing the other surface 32b. is -P _2). Further, ρ is the viscosity coefficient of air, and V is the velocity of the fluid passing between the upstream end of the semicircular portion 35 and the surface 37 facing the upstream end.

  According to the turbine blade 1 according to the present embodiment, the cooling medium flowing along the partition wall 32 in the cooling passage 6 a located on the upstream side of the U-turn portion 17 is a conventional turbine that does not include the bulging portion 34. It is guided by the surfaces of the semicircular portion 35 and the straight portion 36 (along the surfaces of the semicircular portion 35 and the straight portion 36) without being rapidly turned like the partition wall of the blade, and downstream of the U-turn portion 17. Since the air smoothly flows into the cooling passage 6b located on the side, peeling and pressure loss in the U-turn portion 17 can be reduced, and the cooling performance can be improved.

A second embodiment of a turbine blade according to the present invention will be described with reference to FIG.
FIG. 5 is an enlarged view of the main part of the turbine blade according to the present embodiment, which is the same as FIG. 2 and FIG.
The turbine blade 51 according to the present embodiment is described above in that a recess 52 having a circular arc shape in cross section is provided on one surface 32a of the partition wall 32 located on the back side (back side) of the straight portion 36. Different from that of the first embodiment. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above.

As shown in FIG. 5, the recess 52 is formed so that the channel cross-sectional area and the channel width of the cooling passage 6 a are gradually increased on the back side of the straight portion 36, and then gradually decreased to form a straight line with one surface 32 a of the partition wall 32. In the first embodiment described above, the distance from the surface of the portion 36 (that is, the plate thickness of the partition wall 32 in the bulging portion 34) is along the blade thickness direction of the turbine blade 51 (the direction perpendicular to the paper surface in FIG. 5). It is a recess that is reduced more than that of the straight portion 36 and is formed from the vicinity of the back end of the straight line portion 36 to the vicinity of the upstream end of the semicircular portion 35.
Further, the angle θ2 formed between the tangent line at the upstream end and the downstream end of the recess 52 and the one surface 32a of the partition wall 32 is approximately 5 ° or less, that is, no separation occurs at the upstream end and the downstream end of the recess 52. Is set to

  According to the turbine blade 51 according to the present embodiment, the increase in the wall thickness of the partition wall 32 due to the provision of the bulging portion 34 can be minimized, so that the heat capacity of the bulging portion 34 can be reduced, and the swelling is increased. The generation of hot spots due to the provision of the protruding portion 34 can be reduced. In addition, the necessity of increasing the amount of the cooling medium for cooling the hot spot is reduced, and the cooling performance can be further improved.

A third embodiment of a turbine blade according to the present invention will be described with reference to FIG.
FIG. 6 is an enlarged view of the main part of the turbine blade according to the present embodiment, which is the same as FIG. 2 and FIG. 3.
The turbine blade 61 according to the present embodiment communicates a cooling passage 6a positioned upstream through the partition wall 32 and a cooling passage 6b positioned downstream, and a cooling passage 6a positioned upstream of the partition wall 32. The surface 32a forming the first portion 63 has at least one first communication passage 62 having a first opening 63 and a second opening 64 on the surface of the straight portion 36, and the first opening 63 is a second opening 63. It differs from that of the first embodiment described above in that it is positioned closer to the blade tip than the opening 64. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above.

As shown in FIG. 6, the first communication passage 62 is a hole or slit having a central axis (extending direction) that forms an acute angle with the direction of the fluid flowing through the cooling passage 6a. And at least one is formed along the blade thickness direction of the turbine blade 61 (the direction perpendicular to the paper surface in FIG. 6).
The angle formed by the central axis and the direction of the fluid is not limited to an acute angle. If the first opening 63 is located closer to the blade tip than the second opening 64, the angle may be perpendicular or obtuse. I do not care.

  According to the turbine blade 61 according to the present embodiment, the first opening 63 positioned at one end of the first communication path 62 is more than the second opening 64 positioned at the other end of the first communication path 62. Since it is close to the blade tip, the cooling passage 6b located downstream is formed by the pumping effect generated by the centrifugal force in the blade tip direction from the blade root 2 that works when the rotor blade 61 rotates, and has the second opening 64. A part of the cooling medium flowing along the surface of the straight portion 36 flows into the first communication path 62 from the second opening 64 through the first communication path 62, that is, through the first communication path 62. After passing, it flows out from the first opening 63 and is guided (sucked out) into the cooling passage 6a located on the upstream side, so that the separation and pressure loss in the U-turn portion 17 are further reduced. Can further improve the cooling performance. It can be.

A fourth embodiment of a turbine blade according to the present invention will be described with reference to FIG.
FIG. 7 is an enlarged view of the main part of the turbine blade according to the present embodiment, which is the same as FIG. 2 and FIG.
The turbine blade 71 according to this embodiment is different from that of the first embodiment described above in that at least one dimple 72 is provided on the surfaces of the semicircular portion 35 and the straight portion 36. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above.

  As shown in FIG. 7, the dimple 72 is a semicircular (or arc-shaped) dent (dent) in cross section, and extends along the blade thickness direction of the turbine blade 71 (a direction perpendicular to the paper surface in FIG. 7). A large number are formed, and at least one is formed from the vicinity of the upstream end of the semicircular portion 35 to the vicinity of the downstream end of the straight portion 36.

  According to the turbine blade 71 according to the present embodiment, the separation and pressure loss are also reduced by the dimple 72. Therefore, the separation and pressure loss in the U-turn portion 17 can be further reduced, and the cooling performance can be improved. Further improvement can be achieved.

A fifth embodiment of a turbine blade according to the present invention will be described with reference to FIG.
FIG. 8 is an enlarged view of a main part of the turbine blade according to the present embodiment, which is the same as FIG. 2 and FIG.
The turbine blade 81 according to the present embodiment includes two or more serpentine flow paths, and one serpentine flow path is provided at the tip of a rib 82 that partitions one serpentine flow path and the other serpentine flow path adjacent to each other. It differs from that of the first embodiment described above in that at least one second communication path 83 communicating with the other serpentine flow path is provided. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above.

  As shown in FIG. 8, the second communication passage 83 is located at the tip of the rib 82 that partitions the cooling passage 5a that forms one serpentine passage and the cooling passage 6a that forms the other serpentine passage. A hole 85 communicating with the corner 85 on the blade tip side of the surface 37 forming the passage 6a and the corner 86 on the blade tip side of the surface 84 forming the cooling passage 5a located on the back side (back side) One or more slits are formed along the blade thickness direction of the turbine blade 81 (the direction perpendicular to the paper surface in FIG. 8).

  According to the turbine blade 81 according to this embodiment, the tip of the rib 82, that is, the corners (corner portions) 85 and 86 of the U-turn portions 15 and 17, from one serpentine channel to the other serpentine channel. Or the other serpentine flow path to the one serpentine flow path is formed through the second communication path 83, so that the corner portions 85, 86 of the U-turn portions 15, 17 are formed. The occurrence of hot spots in the vicinity can be reduced, and the necessity of increasing the amount of the cooling medium to cool the hot spots is reduced, and the cooling performance can be further improved. Further, peeling and pressure loss at the corners of the U-turn portion can be further reduced, and the cooling performance can be further improved.

The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the gist of the present invention.
For example, the second embodiment may be combined with the third embodiment, the second embodiment or the third embodiment may be combined with the fourth embodiment, or the second embodiment to the fourth embodiment. Any of the above and the fifth embodiment may be combined.

In addition, the present invention is not applied only to one tip of the partition wall provided in the turbine blade 1 having one system serpentine flow path, but to the turbine blade 1 having two or more system serpentine flow paths. The present invention can also be applied to at least one tip portion of at least one provided partition wall.
Further, the present invention can be applied not only to the U-turn portions 15 and 17 located on the blade tip side (tip side) but also to the U-turn portions 16 and 18 located on the blade root side (hub side). be able to.
Furthermore, in the above-described embodiment, the description has been given by taking as an example an example applied to a moving blade (for example, a first stage moving blade) in a turbine section. However, the present invention is directed to a moving blade (for example, a first stage moving blade) in a turbine section. The present invention can be applied not only to the blades of the other stages but also to the blades of other stages.
Furthermore, the first embodiment, the second embodiment, the fourth embodiment, and the fifth embodiment described above can also be applied to a stationary blade in a turbine section.

DESCRIPTION OF SYMBOLS 1 Turbine blade 5a Cooling passage 5b Cooling passage 6a Cooling passage 6b Cooling passage 15 U turn part 17 U turn part 31 Partition 32 Partition 32a One surface (surface)
32b Other side (surface)
33 bulging portion 34 bulging portion 35 semicircular portion 36 linear portion 51 turbine blade 52 dent 61 turbine blade 62 first communication path 63 first opening 64 second opening 71 turbine blade 72 dimple 81 for turbine Wing 82 Rib 83 Second communication path 85 Corner 86 Corner

Claims (9)

A turbine blade having a serpentine flow path that guides a cooling medium supplied from a blade root to the inside of the blade,
A semicircular portion protruding toward the U-turn portion at the tip of the partition wall that partitions the cooling passage located upstream of the U-turn portion of the serpentine channel and the cooling passage located downstream; And a bulging portion that protrudes into the cooling passage located on the side and has a linear section that gradually increases the flow passage cross-sectional area and the passage width of the cooling passage located on the downstream side. Turbine blades characterized by that.   An angle formed between a surface of the partition wall that forms a cooling passage located downstream of the linear portion and a surface of the linear portion is set within a range of 5 degrees to 10 degrees, and the semicircular portion 2. The turbine blade according to claim 1, wherein a value obtained by dividing a radius by a plate thickness of a portion not including the bulging portion of the partition wall is set within a range of 1 to 3. 3.   An angle formed between the surface of the partition wall forming the cooling passage located downstream of the straight line portion and the surface of the straight line portion is set to 10 degrees, and the radius of the semicircular portion is set to the expansion of the partition wall. 3. The turbine blade according to claim 2, wherein a value divided by a plate thickness of a portion not including the protruding portion is set to 1. 4.   The angle formed between the surface of the partition wall forming the cooling passage located downstream of the straight line portion and the surface of the straight line portion is set to 5 degrees, and the radius of the semicircular portion is set to the expansion of the partition wall. 3. The turbine blade according to claim 2, wherein a value obtained by dividing by a plate thickness of a portion not including the protruding portion is set within a range of 2 to 3. 5.   5. The dent having a circular arc shape in cross section is provided on a surface of the partition wall, which is located on the back side of the straight portion and forms a cooling passage located on the upstream side. The turbine blade according to any one of the above.   The cooling passage located on the upstream side and the cooling passage located on the downstream side through the partition are communicated with each other, and a first opening is provided on a surface forming the cooling passage located on the upstream side of the partition. And at least one first communication passage having a second opening on the surface of the straight portion, wherein the first opening is located closer to the blade tip than the second opening. The turbine blade according to any one of claims 1 to 5.   The turbine blade according to any one of claims 1 to 6, wherein at least one dimple is provided on surfaces of the semicircular portion and the straight portion.   A second that includes two or more serpentine channels, and communicates the one serpentine channel and the other serpentine channel to a tip portion of a rib that partitions one serpentine channel and the other serpentine channel adjacent to each other; The turbine blade according to claim 1, wherein at least one communication passage is provided.   A gas turbine comprising the turbine blade according to any one of claims 1 to 8.

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