JP2013144994A - Turbine blade and method for cooling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine blade that can reduce the supply pressure of a cooling medium supplied to a blade root and can reduce a seal leakage air volume from a cavity formed at the blade root to improvement the performance of a gas turbine.SOLUTION: In a turbine blade 1, a plurality of first cooling passages 4 project along a blade shaft direction. A first tapered part 15 is formed to be a folding fan toward a blade edge at an end of an outlet side of the first cooling passage 4.

Description

  The present invention relates to turbine blades (moving blades and stationary blades) applied to gas turbines, steam turbines, etc., in particular, turbine blades having a high blade height installed at the turbine stage rear stage of the gas turbine, and a cooling method thereof It is about.

  As an elongated gas turbine rotor blade installed on the rear stage side of the gas turbine blade row, for example, the one disclosed in Patent Document 1 is known.

JP-A-9-53407

In order to avoid a decrease in strength due to high temperatures, a multihole (a plurality of first cooling passages) is bored in the gas turbine rotor blade having such a length along the blade axis direction. ing.
However, these multiholes have a large pressure loss in order to ensure a necessary heat transfer rate by setting the flow velocity of the cooling air (cooling medium) passing through the inside, and it is necessary to apply a high supply pressure to the blade root.
On the other hand, in general, the extraction air from the compressor is used as the cooling air supply source of the gas turbine rotor blade. To increase the cooling air supply pressure, the cooling air supply source is connected to the rear of the compressor. There is a problem that the performance of the gas turbine deteriorates because it is necessary to take from the stage (high pressure side) and consumes excessive power. Further, since the supply pressure of the cooling air is high, there is a problem that the amount of air leaking from the cavity formed in the blade root portion is increased and the performance of the gas turbine is deteriorated.

  The present invention has been made in view of the above circumstances, and can reduce the supply pressure of the cooling medium supplied to the blade root and reduce the amount of seal leakage air from the cavity formed in the blade root. An object of the present invention is to provide a turbine blade that can improve the performance of a gas turbine and a cooling method thereof.

The present invention employs the following means in order to solve the above problems.
The turbine blade according to the present invention is a turbine blade in which a plurality of first cooling passages are bored along the blade axis direction. A shroud is disposed at a tip of the turbine blade. And a cavity is formed in the shroud so that a plug is inserted from above to form a space in the shroud. The cooling passages communicate with each other, and at the end of the first cooling passage on the outlet side, a first taper portion formed so as to expand toward the blade tip and toward the cavity is formed. Yes.

According to the turbine blade according to the present invention, the first tapered portion is formed at the tip of the first cooling passage, thereby reducing the pressure loss of the cooling medium passing through the first cooling passage. Therefore, the supply pressure of the cooling medium supplied to the blade root can be reduced.
Further, since the supply pressure of the cooling medium can be reduced, the supply source of the cooling medium can be moved to the front stage side (low pressure side) of the compressor, and the power of the compressor for boosting the cooling medium is reduced. And the performance of the gas turbine can be improved.
Further, since the supply pressure of the cooling medium supplied to the blade root portion is reduced, the amount of seal leakage air from the cavity formed in the blade root portion can be reduced.
Furthermore, since the weight of the tip portion is reduced by forming the first tapered portion at the tip portion of the first cooling passage, the centrifugal force applied to the blade root portion can be reduced.
Furthermore, since the first tapered portion is formed at the tip of the first cooling passage, foreign matter such as dust that has reached the first tapered portion through the first cooling passage flows out of the first cooling passage. As a result, clogging of dust at the tip of the first cooling passage can be prevented, and deterioration in cooling performance can be prevented.

  In the turbine blade, a shroud having a plurality of second cooling passages that pass through the first taper portion, flow into the cavity, and flow out of the cooling medium from the cavity to the periphery is provided at the blade tip. Further preferred.

  In the above-described turbine blade, it is more preferable that a second taper portion formed so as to expand toward the end surface of the shroud is formed at an end portion on the outlet side of the second cooling passage.

According to such a turbine blade, the second taper portion is formed at the tip of the second cooling passage, thereby reducing the pressure loss of the cooling medium passing through the second cooling passage. Further, the supply pressure of the cooling medium supplied to the blade root can be further reduced.
Further, since the supply pressure of the cooling medium can be reduced, the supply source of the cooling medium can be moved to the front stage side (low pressure side) of the compressor, and the power of the compressor for boosting the cooling medium is reduced. And the performance of the gas turbine can be improved.
Further, since the supply pressure of the cooling medium supplied to the blade root portion is reduced, the amount of seal leakage air from the cavity formed in the blade root portion can be reduced.
Furthermore, since the second tapered portion is formed at the tip of the second cooling passage, the weight of the tip is further reduced, so that the centrifugal force applied to the blade root can be further reduced.
Furthermore, foreign matters such as dust that have reached the second tapered portion through the second cooling passage are discharged to the outside by forming the second tapered portion at the tip of the second cooling passage. Therefore, it is possible to prevent clogging of dust at the tip of the second cooling passage, and it is possible to prevent a decrease in cooling performance.

  In the turbine blade, it is more preferable that a pressure loss coefficient at an end portion on an outlet side of the first cooling passage is 1.0.

  In the turbine blade, it is more preferable that the first tapered portion is constructed by electrolytic machining or drilling.

  In the turbine blade, it is more preferable that the tapered portion is formed in a region connecting the tip portion of the turbine blade and the main body of the shroud.

  In the turbine blade, it is more preferable that the first cooling passage is one cooling structure selected from the group consisting of a multi-hole, a serpentine cooling passage, and a pin fin cooling structure.

  Since the gas turbine according to the present invention includes any one of the above turbine blades, the performance of the gas turbine can be improved.

In the turbine blade cooling method according to the present invention, a plurality of first cooling passages are bored along the blade axis direction, and a shroud is formed integrally with the turbine blade at the tip of the turbine blade. A cavity is formed in the shroud so that a plug is inserted from above to form a space in the shroud, and the plurality of first cooling passages are respectively formed in the cavity. In the turbine blades that communicate with each other, a step of flowing cooling air through the first cooling passage, and an end portion of the outlet of the first cooling passage so as to expand toward the blade tip and toward the cavity. A step of flowing cooling air through the first tapered portion, and a step of flowing cooling air from the first tapered portion into the cavity, wherein the outlet pressure loss at the tapered portion of the outlet of the first cooling passage is reduced. It is intended to decrease.
According to the method for cooling a turbine blade according to the present invention, since the tapered portion is formed at the tip of the cooling passage, the pressure loss of the cooling medium passing through the cooling passage is reduced. The supply pressure of the cooling medium supplied to can be reduced.
Further, since the supply pressure of the cooling medium supplied to the blade root portion is reduced, the amount of seal leakage air from the cavity formed in the blade root portion can be reduced.
Furthermore, since the weight of the tip portion is reduced by forming the taper portion at the tip portion of the cooling passage, the centrifugal force applied to the blade root portion can be reduced.
Furthermore, since the tapered portion is formed at the tip of the cooling passage, foreign matters such as dust that have reached the tapered portion through the cooling passage are discharged to the outside. Waste clogging can be prevented, and deterioration of cooling performance can be prevented.

  According to the present invention, it is possible to reduce the supply pressure of the cooling medium supplied to the blade root, and thereby the supply source of the cooling air can be moved to the lower pressure side of the compressor. As a result, the gas turbine performance can be improved. In addition, the amount of seal leakage air from the cavity formed in the blade root can be reduced, and the performance of the gas turbine can be improved.

It is a longitudinal cross-sectional view of the blade for turbines concerning 1st Embodiment of this invention. It is AA arrow sectional drawing of FIG. It is BB arrow sectional drawing of FIG. It is CC sectional view taken on the line of FIG. It is a figure for demonstrating the effect of the turbine blade which concerns on this invention, Comprising: (a) is a figure for demonstrating the pressure loss which arises in the conventional multihole, (b) is the multihole which concerns on this embodiment. It is a figure for demonstrating the pressure loss which arises. It is a figure of the blade for turbines concerning 2nd Embodiment of this invention, Comprising: It is a figure similar to FIG.

Hereinafter, a turbine blade according to a first embodiment of 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 a sectional view taken along the line A-A in FIG. 1, FIG. 3 is a sectional view taken along the line BB in FIG. CC sectional view, FIG. 5 is a figure for demonstrating the effect of the turbine blade which concerns on this embodiment, Comprising: (a) is a figure for demonstrating the pressure loss which arises in the conventional multihole, (B) is a figure for demonstrating the pressure loss which arises in the multihole which concerns on this 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 present invention can be applied to an elongated turbine blade having a high blade height installed in a turbine rear stage of the turbine.

  In the figure, reference numeral 2 is a shroud at the tip, and reference numeral 3 is a fin provided on the shroud 2. Reference numeral 4 is a multi-hole (a plurality of first cooling passages) drilled in a turbine blade (hereinafter referred to as “turbine rotor blade”) 1, and reference numeral 5 is provided on the inner wall of the turbine rotor blade 1. Pin fins, reference numeral 6 is a rib for supporting the cavity 7, reference numeral 8 is a hub portion, and reference numeral 9 is a blade root portion.

  As shown in FIG. 3, two cavities 10 and 11 are independently formed inside the shroud 2, and a plug (cap) 12 is provided in each of the cavities 10 and 11 as shown in FIG. A space is formed inside the shroud 2 by being inserted from the upper surface side. The multiholes 4 communicate with the cavities 10 and 11, respectively, and cooling air (cooling medium) 13 described later is supplied. In addition, the cooling air 13 uses the extraction air from a compression part as a supply source (not shown). In addition, a plurality of cooling passages (second cooling passages) 14 are communicated with the cavities 10 and 11 toward opposite sides, and the cooling passages 14 are opened at both end surfaces of the shroud 2, respectively. The cooling air 13 flows out.

  The cooling air 13 flows from the blade root portion 9 into the cavity 7 as shown by solid arrows in FIG. 1, improves the heat transfer coefficient by the pin fins 5, cools the base portion, flows through the multihole 4, and moves to the tip portion. Led. The cooling air 13 guided to the tip portion flows into the cavities 10 and 11 of the shroud 2, passes through the cooling passages 14 from the cavities 10 and 11, and flows out from openings formed at both end surfaces of the shroud 22, Cool the whole of 2.

  An integral shroud 2 is integrally formed with the turbine rotor blade 1 at the tip of the turbine rotor blade 1. The shroud 2 reduces the gas leaked from the tip of the turbine blade 1, and presses the end surface of the shroud 2 against the end surface of the adjacent shroud 2 to form a series of group blades. The vibration intensity is improved. The turbine rotor blade 1 generates vibrations in two directions, that is, the rotation axis direction and the circumferential direction. By forming the end surface of the shroud 2 diagonally as shown in FIG. 3, vibrations in both directions are suppressed. . In addition, the shroud 2 is provided with fins 3 formed by integral casting, scraping or the like in order to reduce gas leaking from the tip of the turbine rotor blade 1 and to prevent contact with the casing side. .

  Now, the turbine rotor blade 1 according to the present embodiment has a multihole 4 as shown in FIG. 4, that is, a taper portion (first taper portion) 15 at a tip portion (end portion on the outlet side: outlet portion). A multi-hole 4 is provided. The taper portion 15 is a portion having a truncated cone shape formed so as to be widened toward the cavity 10 (or the cavity 11) (from the inlet end toward the outlet end) (to gradually increase in diameter). It is constructed by electrolytic processing or drilling. Moreover, the taper angle (angle formed by the central axis C1 of the multi-hole 4 and the inner wall surface 16 of the taper portion 15) α is set to 5 ° to 10 °.

5A shows a conventional multi-hole 4A that does not have the tapered portion 15, and FIG. 5B shows the multi-hole 4 according to the present embodiment that has the tapered portion 15. FIG.
Here, the cross-sectional area at the inlet end and the outlet end of the multihole 4A, the inlet end of the multihole 4 and the inlet end of the tapered portion 15 is A1, the sectional area at the outlet end of the tapered portion 15 is A2, and the multihole 4A and the multihole The flow velocity of the cooling air 13 at the inlet end of the hole 4 is V0, the flow velocity of the cooling air 13 at the outlet end of the multihole 4A and the inlet end of the tapered portion 15 is V1, and the flow velocity of the cooling air 13 at the outlet end of the tapered portion 15 is V2. And
Further, the flow velocity of the cooling air 13 in the middle part of the multiholes 4A, 4 is Vmid, the density of the cooling air 13 at the inlet end of the multiholes 4A, 4 is γ0, the outlet end of the multihole 4A, and the inlet end of the tapered part 15 The density of the cooling air 13 at γ1 is γ1, and the density of the cooling air 13 at the intermediate part between the multiholes 4A and 4 is γmid.
Further, ζin is a pressure loss coefficient at the inlet ends of the multiholes 4A and 4, and ζout is a pressure loss coefficient at the outlet ends of the multiholes 4A and 4 and is 1.0. ζmid is a pipe friction pressure loss coefficient of the multiholes 4A and 4.
As a result, when the total pressure loss (inlet pressure loss + pipe friction pressure loss + outlet pressure loss) of the multi-holes 4A, 4 is ΔPA and ΔP, respectively, it can be expressed approximately by the following [Equation 1] and [Equation 2]. it can.

  Here, g is a gravitational acceleration. Accordingly, the difference Δp between ΔPA and ΔP is only the difference in the outlet pressure loss, and is expressed by the following [Equation 3].

  If the flow rate is the same, the relationship between the flow velocity and the cross-sectional area is expressed as the following [Equation 4].

  If [Equation 3] is rewritten using [Equation 4] and ζout = 1.0, Δp is expressed as [Equation 5] below.

  From this, since A1 <A2, Δp> 0 and it can be seen that the pressure loss coefficient of the multihole 4 is smaller than the pressure loss of the multihole 4A. As a result, the supply pressure of the cooling air 13 at the inlet end of the multihole 4 can be reduced by Δp.

According to the turbine rotor blade 1 according to the present embodiment, the tapered portion 15 is formed at the tip portion of the multi-hole 4, thereby reducing the pressure loss of the cooling air 13 passing through the multi-hole 4. The supply pressure of the cooling air 13 supplied to the blade root 9 can be reduced, and the performance of the gas turbine can be improved.
Further, since the supply pressure of the cooling air 13 can be reduced, the supply source of the cooling medium can be moved to a lower pressure side of the compression unit, and the power of the compression unit for boosting the cooling air 13 can be reduced. The performance of the gas turbine can be improved.
Further, since the supply pressure of the cooling air 13 supplied to the blade root portion 9 is reduced, the amount of seal leakage air from the cavity formed in the blade root portion can be reduced, and the performance of the gas turbine is further improved. be able to.
Furthermore, since the weight of the tip portion is reduced by forming the tapered portion 15 at the tip portion of the multihole 4, the centrifugal force applied to the blade root portion 9 can be reduced.
Furthermore, since the tapered portion 15 is formed at the tip of the multihole 4, foreign matters such as dust that have reached the tapered portion 15 through the multihole 4 smoothly flow into the cavities 10 and 11. Therefore, clogging of dust at the tip of the multi-hole 4 can be prevented, and deterioration of the cooling performance can be prevented.

A turbine blade according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a view of the turbine blade according to the present embodiment, and is the same view as FIG.
The turbine rotor blade 21 according to the present embodiment has a cooling passage 14 as shown in FIG. 6, that is, a cooling passage having a tapered portion (second tapered portion) 22 at a tip portion (end portion on the outlet side: outlet portion). 23 is different from that of the first embodiment described above. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.

  The taper portion 22 is a portion exhibiting a truncated cone shape formed so as to expand toward the end face of the shroud 2 (from its inlet end toward its outlet end) (so that the diameter gradually increases), It is constructed by electrolytic processing or drilling. Further, a taper angle of the taper portion 22 (an angle formed by the central axis C2 of the cooling passage 23 and the inner wall surface 24 of the taper portion 22) β is set to 5 ° to 10 °.

According to the turbine rotor blade 21 according to the present embodiment, the tapered portion 22 is formed at the distal end portion of the cooling passage 23, thereby reducing the pressure loss of the cooling air 13 passing through the cooling passage 23. The supply pressure of the cooling air 13 supplied to the blade root portion 9 can be further reduced, and the performance of the gas turbine can be further improved.
Further, since the supply pressure of the cooling air 13 can be reduced, the supply source of the cooling medium can be moved to a lower pressure side of the compression unit, and the power of the compression unit for boosting the cooling air 13 can be reduced. The performance of the gas turbine can be further improved.
Further, since the supply pressure of the cooling air 13 supplied to the blade root portion 9 is reduced, the amount of seal leakage air from the cavity formed in the blade root portion can be reduced, and the performance of the gas turbine is further improved. be able to.
Furthermore, since the weight of the tip portion is further reduced by forming the tapered portion 22 at the tip portion of the cooling passage 23, the centrifugal force applied to the blade root portion 9 can be further reduced.
Furthermore, since the tapered portion 22 is formed at the tip of the cooling passage 23, foreign matters such as dust that have reached the tapered portion 22 through the cooling passage 23 are discharged to the outside. It is possible to prevent clogging of dust at the tip end portion of 23, and it is possible to prevent a decrease in cooling performance.

Further, as shown in FIGS. 4 and 6, it is more preferable that the tapered portion 15 is formed in the position of R of the shroud 2, that is, in a region connecting (connecting) the tip end portion of the blade body and the shroud body. is there.
Thereby, the mechanical strength at the R position of the shroud 2 can be ensured without increasing the wall thickness at the R position of the shroud 2.

In the above-described embodiment, the cross-sectional view shapes of the multihole 4, the taper portion 15, the cooling passage 23, and the taper portion 22 are preferably circular in view of ease of manufacture, but the present invention is not limited to this. The shape is not limited to the above, and may be any shape such as an elliptical shape or a polygonal shape.
In the above-described embodiment, the multihole 4 and the tapered portion 15 are connected to the cooling passage 23 and the tapered portion 22 via the corner portion, but the present invention is not limited to this. For example, it can be smoothly connected via a rounded R portion (or chamfered portion).

In the above-described embodiment, the tapered portion 15 is provided in the multi-hole 4. However, the tapered portion 15 may be omitted and the tapered portion 22 may be provided in the cooling passage 23 of the shroud 2.
Furthermore, the cooling passage inside the blade may have a configuration other than multi-holes, for example, other cooling structures such as a serpentine cooling passage or a pin fin cooling structure, and is not limited to this embodiment.
In the embodiment described above, the cooling medium is extracted air from the compression unit. However, the present invention can also be applied to other cooling media, for example, a steam cooling type gas turbine using steam as a cooling medium. For example, in a combined plant, when steam from an exhaust heat steam generator that generates steam by exhaust heat of a gas turbine is used as a cooling medium, the pressure of the steam to be used can be reduced, and the amount of steam used can also be reduced. Plant efficiency can be improved.

1 Turbine blade 2 Shroud 4 Multihole (multiple first cooling passages)
13 Cooling air (cooling medium)
15 Taper (first taper)
21 Turbine blade 22 Tapered portion (second tapered portion)
23 Cooling passage (second cooling passage)

Claims (9)

A turbine blade in which a plurality of first cooling passages are bored along the blade axis direction.
A shroud is formed integrally with the turbine blade at the tip of the turbine blade,
Inside the shroud, a plug is inserted from the upper surface side, and a cavity is formed so that a space is formed inside the shroud,
The plurality of first cooling passages communicate with the cavity, respectively.
A turbine is characterized in that a first taper portion is formed at an end portion on the outlet side of the first cooling passage so as to be widened toward a blade tip and toward the cavity. Wings.   A shroud having a plurality of second cooling passages that pass through the first taper portion, flow into the cavity, and flow out of the cooling medium from the cavity to the periphery is provided at a blade tip. The turbine blade according to claim 1.   3. The turbine according to claim 2, wherein a second taper portion formed so as to expand toward the end surface of the shroud is formed at an end portion on an outlet side of the second cooling passage. Wings.   The turbine blade according to any one of claims 1 to 3, wherein a pressure loss coefficient at an end portion on an outlet side of the first cooling passage is 1.0.   The turbine blade according to any one of claims 1 to 4, wherein the first tapered portion is constructed by electrolytic machining or drilling.   The turbine blade according to any one of claims 1 to 5, wherein the tapered portion is formed in a region connecting a tip portion of the turbine blade and a main body of the shroud.   7. The turbine according to claim 1, wherein the first cooling passage is one cooling structure selected from the group consisting of a multi-hole, a serpentine cooling passage, and a pin fin cooling structure. Wings.   A gas turbine comprising the turbine blade according to any one of claims 1 to 7. A plurality of first cooling passages are bored along the blade axis direction inside,
A shroud is formed integrally with the turbine blade at the tip of the turbine blade,
Inside the shroud, a plug is inserted from the upper surface side, and a cavity is formed so that a space is formed inside the shroud,
In the turbine blade in which the plurality of first cooling passages communicate with the cavity,
Flowing cooling air through the first cooling passage;
Flowing cooling air through the first taper portion at the exit end of the first cooling passage toward the blade tip and toward the cavity,
Flowing cooling air from the first taper to the cavity,
A method for cooling a blade for a gas turbine, characterized by reducing an outlet pressure loss at a tapered portion of an outlet of the first cooling passage.

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