JPH1150806A - Nozzle member for gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it difficult to generate any shrinkage (partly shrinkage) or inclusion (sand inclusion) during casting so as to increase a product yield, reduce the necessity of re-designing or re-manufacturing a wax pattern so as to reduce a wax pattern manufacturing cost in the case of adjustment of a throat area by slightly changing an angle of a stator blade at a prototype stage, and reduce a stress generated at the rear edge of a stator blade tip or the downstream end of an outer shroud in the use state so as to prolong a lifetime. SOLUTION: A rib 11 is provided for connecting a pair of hooks 5 spaced with an interval in a direction of a gas flow 3 and is brought into close contact with the outer face of an outer shroud 12. The circumferential thickness B of the rib 11 is set in such a manner as to encompass most of a region 14 where a stator blade tip is brought into contact with the outer shroud 12 within a predetermined adjustable angular range around a rear edge 13a. The hooks 5 are provided upstream of the rear edge 13a of a stator blade, thus preventing a load from the stator blade to the hooks from bypassing the rear edge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine nozzle member in which an outer shroud portion, a stationary blade portion and an inner shroud portion are integrally formed.

[0002]

2. Description of the Related Art FIG. 7 shows a configuration example of a cascade of gas turbines. As shown in this figure, the gas turbine is usually a cascade composed of a plurality of (four in this example) stationary blade rows 1 and moving blade rows 2. The cascade 2 recovers energy from the gas flow 3 to obtain rotational power. Further, as shown in this figure, the downstream side of the gas flow path (the right side in the figure) gradually widens.

FIG. 8 shows a nozzle member 4 constituting a stator blade row 1.
It is a perspective view of. As shown in this figure, the nozzle member 4 has a fan shape divided in the circumferential direction. Further, each nozzle member 4 includes an outer shroud portion 4a, a stationary blade portion 4b, and an inner shroud portion 4c which are integrally formed, and a plurality of nozzles formed by fixing a hook portion 5 outside the outer shroud portion 4a to an inner surface of a casing. The members 4 are tightly connected in the circumferential direction to form one stationary blade row 1. In FIG. 7, a seal plate 6 is sandwiched between adjacent nozzle members 4 to perform gas sealing therebetween.

[0004]

The nozzle member 4 shown in FIG. 8 is usually manufactured by a lost wax method. Therefore, in order to improve the flow of hot water from the hook portion 5, a rib portion 5a (see FIG. 7) is provided between the two hook portions 5, and from the outer shroud portion 4a to the stationary blade portion 4b via the rib portion 5a. It is designed to flow molten metal.

However, in the conventional nozzle member, the shape of the rib portion of the outer shroud is defined by using the two-dimensional cross-sectional shape of the blade tip portion. Therefore, as shown in FIG. When the taper is sharp and the airfoil shape changes greatly in the radial direction, the actual intersection curve between the blade tip portion and the flow path surface and the rib shape are shifted at the leading edge and the trailing edge. Therefore, there is a problem that the flow of molten metal during casting is deteriorated, shrinkage (partial shrinkage), inclusion (sand mixing), and the like are likely to occur, and the yield of cast products is low.

[0006] In addition, the position of the hook portion of the conventional outer shroud in the axial direction has not been optimized in consideration of future airfoil changes. For this reason, the throat area is usually adjusted by slightly changing the angle of the stationary blade at the stage of prototype production, but every time the stationary blade angle is changed, the wax type of the outer shroud including the hook is redesigned However, it has to be re-manufactured, and the production cost of the wax mold is very high (for example, 10 million yen or more). In other words, it was necessary to change the expensive cast brazing die set as it was by changing the airfoil, which greatly affected the development schedule and cost.

Further, in the use state, the force received by the stationary blade from the gas flow is transmitted to the hook portion via the outer shroud portion. At this time, the trailing edge of the stationary blade tip portion, particularly the rear edge portion and the outer shroud portion, are transmitted. High stress was generated at the downstream end, cracks were easily formed, and the life was short. In other words, when the axial position is not optimized, if the hook of the outer shroud comes directly above the wing edge due to the airfoil change, the load transmission path will pass through the structurally weak wing edge. However, it was not preferable in terms of the durability of the parts.

The present invention has been made to solve the various problems described above. That is, an object of the present invention is to reduce shrinkage and inclusion during casting and increase the product yield, and to adjust the throat area by slightly changing the angle of the stationary blade at the prototype stage. Reduces the need to redesign and remanufacture the mold, reducing the cost of producing the wax mold, and reducing the stress generated at the trailing edge of the stationary blade tip and the downstream end of the outer shroud in use. Accordingly, it is an object of the present invention to provide a gas turbine nozzle member that can extend its life.

[0009]

According to the present invention, there is provided a gas turbine nozzle member in which an outer shroud portion having an outer hook portion and a stationary blade portion comprising a plurality of stationary blades are integrally formed. A rib portion that connects a pair of hook portions that are spaced apart in the flow direction of the outer shroud portion and that is in close contact with the outer surface of the outer shroud portion within a predetermined adjustment angle range centered on the trailing edge. A nozzle member for a gas turbine, wherein a circumferential thickness thereof is set so as to cover most of a region where a blade tip portion contacts an outer shroud portion.

According to the configuration of the present invention, the circumferential thickness of the rib portion connecting the hook portions is set so as to cover most of the region where the vane tip portion contacts the outer shroud portion. Therefore, the molten metal can flow smoothly from the outer shroud portion to the stationary blade portion via the rib portion, and shrinkage, inclusion, and the like can be prevented, and the yield of the cast product can be increased.

That is, the rib section and the blade tip section are defined by defining an intersection curve between the blade tip section and the flow path surface on a three-dimensional CAD and projecting the shape on a plane. Since the portions overlap each other, the molten metal can flow smoothly from the rib portion to the blade tip portion through the outer shroud portion. Further, since the vane tip portion is set so as to cover most of the region in contact with the outer shroud portion within a predetermined adjustment angle range centered on the trailing edge, the vane is moved in this range. When adjusting the throat area by swinging around the center, each casting wax mold can be applied as it is just by shifting the position partially,
The development cost can be reduced and the development schedule can be shortened.

According to a preferred embodiment of the present invention, the pair of hooks is provided upstream of a trailing edge of the stationary blade, so that load transmission from the stationary blade to the hook passes through the trailing edge. Not to be. With this configuration, the load acting on the trailing edge portion of the stationary blade can be reduced, the stress generated in this portion can be reduced, and the life can be extended.

A seal plate for sealing a gap between the nozzle members is provided only between the pair of hook portions. With this configuration, compared to the conventional example in which the seal plate is provided up to the rear end portion of the outer shroud portion, the stress generated in this portion can be reduced, and the life can be extended.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is a partial configuration diagram schematically showing a nozzle member of the present invention. In this figure, (A) is a longitudinal sectional view of the outer shroud portion of the nozzle member, (B) is a view taken in the direction of arrow BB, and (C).
Shows a cross-sectional view taken along line CC. As shown in FIG. 1A, the nozzle member 10 of the present invention has a pair of hook portions 5 spaced apart in the flow direction of the gas flow 3 on the outside, and the outer shroud portion 12 is provided between the hook portions 5. The rib part 11 closely contacted with the outer surface is connected.

As shown in FIGS. 1B and 1C, the rib portion 11 has an outer shroud portion 1 having a stationary blade tip portion within a predetermined adjustment angle range centered on the trailing edge 13a of the stationary blade 13.
The peripheral thickness B is set so as to cover most of the region 14 that contacts the second portion 2. This adjustment angle range is
For example, it is preferable to provide about ± 2 degrees. That is, the shape of the rib member 11 serving as the metal hot water supply path at the time of casting is set so as to coincide with the above-mentioned intersection curve 14, and the width is increased by a necessary amount in preparation for a future airfoil change.

FIG. 2 is a side view of the nozzle member of the present invention. As shown in this figure, the nozzle member 10 of the present invention
The pair of hook portions 5 are provided upstream of the trailing edge 13a of the stationary blade 13 so that the stationary blade 13
The load is not transmitted to the trailing edge 13a. In this example, the hook 5 is provided downstream of the front edge 13b so that no load acts on the front edge 13b. With this configuration, the load acting on the trailing edge portion of the stationary blade can be reduced, the stress generated in this portion can be reduced, and the life can be extended.

Even if the blade cord length is shortened by changing the blade shape, the blade edge portion (particularly the trailing edge 13) is structurally weak.
It is preferable that a) does not enter the inside of the hook portion 5.

FIG. 3 is a diagram showing an intersection curve between the blade tip portion and the flow path surface and projecting the intersection curve on a two-dimensional plane. (A) is a conventional example, and as described above, in the conventional nozzle member, the rib shape of the outer shroud is defined by using the two-dimensional cross-sectional shape 7 of the wing tip portion. When the airfoil shape is tight and the airfoil shape changes greatly in the radial direction, the actual intersection curve between the airfoil tip portion and the flow path surface and the rib shape are shifted at the leading edge and the trailing edge. (B) (C)
Is an example of the present invention. In order to eliminate the deviation of (A), first, an intersection curve 9 between the blade tip portion and the flow path surface is defined on a three-dimensional CAD, and its shape is defined by projecting it on a plane. Also,
In preparation for a future airfoil change, the rib member 11 is made as thick as necessary so as not to be displaced from the blade tip even after the change.

As described above, the occurrence of defects during casting can be suppressed by eliminating the deviation. In addition, by increasing the rib shape by the required amount, even if the airfoil needs to be changed in the future, the casting wax mold can be handled simply by changing only the wing insert, so that the development schedule, cost,
There are very benefits.

FIGS. 4A and 4B are model diagrams for analyzing a hook position, wherein FIG. 4A shows a conventional example and FIG. 4B shows a case of the present invention. (A) In the conventional example, a pair of hook portions 5 are located upstream of the leading edge of the stationary blade and downstream of the trailing edge, and the fluid force acting on the stationary blade passes through the leading edge and the trailing edge. The load is transmitted to the hook. For this reason, as a result of the analysis, a maximum stress of about 32 ksi and 35 ksi was generated at the leading edge and the trailing edge, respectively.

On the other hand, in the present invention shown in FIG.
As shown in FIG. 2, the pair of hook portions 5 are provided upstream of the trailing edge 13a of the stationary blade 13 and downstream of the leading edge 13b, whereby the load is transmitted from the stationary blade 13 to the hook portion 5. Does not pass through the front edge 13b and the rear edge 13a. For this reason, the load acting on the trailing edge of the stationary blade can be reduced, and as a result of analysis, it has been found that the maximum stress of the leading edge and the trailing edge can be reduced to about 13 ksi and 18 ksi, respectively.

FIG. 5 is a model diagram of the nozzle member showing the position of the seal support portion, and FIG. 6 is a stress distribution diagram showing an example of the analysis result in the case of FIG. In the conventional example, as shown in FIG. 5, a block-shaped seal support 4c is provided also on the downstream side of the hook portion, and the adjacent seal support 4c is provided.
This portion was gas-sealed by sandwiching a seal plate between them. However, as shown in FIG. 6, when the seal support 4c is provided, the MX
High stress is generated in the portion, especially about 47
The analysis showed that ksi was reached. In addition, A to K in FIG. 5 indicate the generated stress in ascending order, of which K is 14 kgf / mm ² .

From this analysis result, the seal plate for sealing the gap between the nozzle members of the present invention is provided only between the pair of hook portions 5, and the structure without the seal support shown in FIG. It has become.

According to the above-described present invention, the circumferential thickness of the rib portion 11 connecting the hook portions 5 covers most of the region 14 where the stationary blade tip portion contacts the outer shroud portion 12. Since it is set, the molten metal can flow smoothly from the outer shroud portion 12 to the stationary blade portion 13 via the rib portion 11, and shrinkage, inclusion, and the like can be prevented, and the yield of the cast product can be increased. .

Further, within a predetermined adjustment angle range centered on the trailing edge 13a, the stationary blade tip portion is connected to the outer shroud portion 12a.
When the throat area is adjusted by swinging the stationary blade 13 around the trailing edge 13a in this range, each casting brazing die It can be applied as it is by only partially displacing the position, lowering the development cost and shortening the development schedule.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

[0027]

As described above, the nozzle member of the gas turbine according to the present invention is less prone to shrinkage (partial shrinkage) or inclusion (sand mixing) during casting, can increase the product yield, and can be manufactured as a prototype. When adjusting the throat area by slightly changing the angle of the stationary blade at the stage, the need for redesign and remanufacture of the wax type can be reduced, and the cost of manufacturing the wax type can be reduced, and the static state in use can be reduced. Stress generated at the trailing edge of the wing tip and at the downstream end of the outer shroud can be reduced to extend the service life.
And so on.

[Brief description of the drawings]

FIG. 1 is a partial configuration diagram schematically showing a nozzle member of the present invention.

FIG. 2 is a side view of the nozzle member of the present invention.

FIG. 3 is a diagram showing an intersection curve between a blade tip portion and a flow path surface and projecting the intersection curve on a two-dimensional plane.

FIG. 4 is a model diagram for analyzing a hook position.

FIG. 5 is a model diagram of a nozzle member showing a position of a seal support portion.

FIG. 6 is a stress distribution diagram showing an example of an analysis result.

FIG. 7 is a cascade diagram of a gas turbine.

FIG. 8 is a perspective view of a nozzle member constituting a stationary blade row.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator blade row 2 Moving blade row 3 Gas flow 4 Nozzle member 4a Outer shroud part 4b Stator blade part 4c Inner shroud part 5 Hook part 5a Rib part 6 Seal plate 7 Two-dimensional sectional shape 8 Flow path surface 9 Intersection curve 10 Nozzle member 11 Rib member 12 outer shroud portion 13 stationary blade 13a trailing edge 13b leading edge 14 contact area

Claims (3)

[Claims] A nozzle member of a gas turbine in which an outer shroud portion having a hook portion on an outer side and a stationary blade portion including a plurality of stationary blades are integrally formed, a pair of nozzle members spaced apart in a gas flow direction. And a rib portion that connects between the hook portions and is in close contact with the outer surface of the outer shroud portion. The rib portion makes the vane tip contact the outer shroud portion within a predetermined adjustment angle range centered on the trailing edge. A gas turbine nozzle member having a circumferential thickness set so as to cover most of a region. 2. The pair of hook portions are provided upstream of a trailing edge of the stationary blade, so that load transmission from the stationary blade to the hook portion does not pass through the trailing edge. The nozzle member for a gas turbine according to claim 1, wherein: 3. The gas turbine nozzle member according to claim 2, wherein a seal plate for sealing a gap between the nozzle members is provided only between the pair of hook portions.