JPS59160009A - Stationary blade for gas turbine - Google Patents

Abstract

PURPOSE:To improve a gas turbine in its operating efficiency, by arranging such that while the head portion of stationary blade is formed with a ceramics and a hole and the like are provided in the platform of stationary blade and a shroud for securing the head portion therein, a small diameter hole is bored in the interior surface of hole and the like. CONSTITUTION:The head portion 12 of stationary blade 1 is separated away from a body portion 13 by a curved, or a bent line and the like such that its dividing line may take a large contact angle relative to the outer surface of blade, the curved or the bent line providing the body 13 side with a convexed portion. The head portion 12 is formed with a ceramics. On the other hand, the body 13, the platform 18 and the shroud 19 are formed with a heat resistant alloy. A hole 21 and a recess 22, slightly larger than the diameter of head portion 12 are defined in the platform 18 and the shroud 19. The head portion 12 is inserted into the recess 22 through the hole 21, and a cap 20 is placed over the hole 21. A cooling air blow-off port 24 with a reduced diameter is bored through the platform 18, the shroud 19 and the cap 20. By so arranging, it becomes unnecessary to lower the volume of cooling air and the pressure of the main stream gas, thereby achieving the object of present invention.

Description

[Detailed Description of the Invention] The present invention primarily relates to stationary blades for gas turbines used in high-temperature gas turbines, etc.In recent years, gas turbines have tended to have higher temperatures in order to improve performance and increase output. Because of this, gas turbine blades are exposed to high temperatures, but there are currently no materials that have strength at such high temperatures, so a method of cooling the blades is adopted, which is used in conventional gas turbines. A stator blade (hereinafter abbreviated as a blade for convenience in this description) is a blade 1 made of a hollow blade, as shown in the examples of Fig. 1-A, Fig. 1-B, Fig. 1-C, and Fig. 1-D. A core 4 is provided in a hollow blade 1, and the core 4 is
The one shown in Figure 1-B in which cooling air is introduced into the core 4, and the air is blown out toward the inner surface of the blade through numerous pores 5 at the tip of the core 4 to locally increase heat transfer and force cooling. Cooling air is guided into the hollow blade 1, and is blown out from the numerous pores 6 at the leading edge of the blade, covering the blade 1 with a cooling air layer, insulating heat from the high-temperature combustion gas, and creating a film-cooled air layer. There are blades such as those shown in Fig. 1-C, and as gas turbines become hotter, a combination of these blades is used, leading to the blade 1 shown in Fig. 1-D.

In addition, as shown in the conventional example in Fig. 1-E, cooling air is also blown out from the cooling air blowing holes 24 on the passage surfaces of the platform 18 and the shroud 19. , the same parts are indicated by the same part numbers.

In addition, in the said FIG. 1-A to FIG. 1-D, the same parts are shown by the same part number.

Here, since the leading edge of the blade 1 of the gas turbine that is exposed to the combustion gas and reaches the highest temperature is the leading edge of the blade 1 where the mainstream gas is dammed up, cooling this front part is the most important.
As the temperature of gas turbines increases, film cooling is also used, and the amount of cooling air required to cool this part is also increasing.

However, if the blade 1 is film-cooled and the amount of cooling air required for this increases, the amount of cooling air mixed with the mainstream gas will increase, the average mainstream gas temperature will decrease, and this will reduce the cycle efficiency of the gas turbine. will decrease.

In addition, the cooling air that cools the blades 1 is normally produced by extracting air compressed by a compressor 8 driven by the turbine section 1o of the gas turbine before the combustor 9, as shown in the system diagram in Fig. 2. The air is then supplied into the blade 1 through the casing or 1 and piping connected thereto.

For this reason, if the amount of cooling air increases, the power required for compression at compression g1.8 will increase, and the efficiency and output of the gas turbine 10 will decrease by this amount.

In addition, in order to achieve complete film cooling, the pressure difference between the cooling air and the pressure of the mainstream gas needs to be appropriate. Gas may flow back inside the blade, impairing cooling performance, and conversely, if the pressure difference is too large, the cooling air will blow out forcefully, and if the blowing angle to the blade surface is large, the cooling air layer along the blade surface will collapse. is difficult to form, and even aerodynamic performance is impaired.

In general, the pressure of the mainstream gas is only slightly lower than the pressure of the cooling air, so the flow from the outlet of the compressor 8 in the mainstream gas system to the blade row of the turbine section 1o of the gas turbine takes place before the blowing is completed. In the meantime, provide aperture resistance, etc.
In some cases, the power of the mainstream gas may be lowered.

＼1 In this way, lowering the pressure of the mainstream gas does not involve work, resulting in IT loss and the output decreases.

In addition, when cooling air is blown out from each part of the blade 1 to perform fringe cooling, there is a pressure distribution in the mainstream gas along the blade surface, and there is a need for a reservoir to blow out a predetermined amount of cooling air at each location. The wing structure is complex.

Further, providing cooling air blow-off holes requires a lot of processing time, increases costs, reduces strength, and shortens blade life.

As mentioned above, in the conventional cooling type blade structure, as the temperature of the gas turbine increases, film cooling is performed from the leading edge of the blade, and the amount of cooling air required for this increases, so the mainstream gas cooling There were problems such as a decrease in the thermal efficiency of the gas turbine due to this, a large loss in the required power of the compressor, and a decrease in the output image due to the lowering of the downstream gas pressure, so countermeasures against this problem were strongly desired.

SUMMARY OF THE INVENTION Therefore, the present invention has been made with the object of solving the above-mentioned conventional problems and making it possible to improve the efficiency of a gas turbine.

・In other words, the present invention provides a structure in which:
It is separated from other stator blade structures and is made of ceramic, and holes or grooves are provided in the platform and shroud of the stator blade, and both upper and lower ends of the head are installed in these holes or grooves. It is constructed by providing pores for blowing and discharging cooling air on the inner surface of these holes or grooves.

The present invention will be described in detail below with reference to the drawings.
The figure is a cross-sectional view of the stator blade of a gas turbine according to an embodiment of the present invention, FIG. 4 is a cross-sectional view of the stator blade shown in FIG. 3 along the camber line, and FIG. FIG. 1 is a cross-sectional view of several heads of the conventional example shown in FIGS. 1-A to 1-D.

First, in the blade 1 of the present invention applied to the turbine section 10 of a gas turbine similar to that described in the conventional example of FIG.
12 is the head, 13 is the main body, 14 is the hollow tip, 15
is a partition, 16 is a cooling air passage, 17 is a cooling air outlet at the tip, 18 is a platform, 19 is a shroud,
And 2o is the cap.

Next, in this wing 1, the head 12 is made of ceramic, and the main body 16, platform 18, and shroud 19 are made of metal 1, that is, a heat-resistant base t.

The range of the head 12 is the b1 range where the mainstream gas is dammed,
Alternatively, it should be within the range where the heat transfer coefficient is high.

Further, the head 12 is curved so that the main body 13 side is convex,
Alternatively, it is separated from the main body portion 16 by a broken line or the like such that the angle at which the dividing line contacts the blade row surface is large.

Further, the main body portion 13, the platform 18, and the shroud 19 are integrated.

Further, the platform 18 is provided with a hole 21 that is slightly larger than the head 12, and the shroud 19 is also provided with a groove 22 that is slightly larger than the head 12. A cap 20 is attached to 21, and the upper end of the cap 20 is welded all around.

The main body part 16 is provided with a hollow part divided into a tip part 14 and a rear edge part 2 by a partition 15, and a number of small cooling air blowing holes 17 are bored at the tip, and the outer surface, that is, the head A cooling air passage 16 is provided on the mating surface with the rear edge portion 2.
The hollow part has an internal convection cooling structure.

In the plant form 18, a small cooling air blowing hole 24 is formed in the inner surface of the hole 21, and in addition, a small cooling air blowing hole 24 is formed in the lower end surface of the cap 20. The shroud 19 is provided with fine cooling air blowing holes 24 in the inner surface of the grooves 22.

The present invention is configured as described above, and guides cooling air to both the platform 18 and the shroud 19.
Cooling air is blown from the cooling air blowing holes 24 to the inner surfaces of the holes 21 and the grooves 22 to prevent heat transfer from the head 12 to the platform 18 and shroud 19, and the cooling air guided to the platform 18 side is The cooling air that is guided into the hollow portions of the tip portion 14 and the rear edge portion 2 is passed between the head portion 12 and the body portion 16 through the cooling air outlet 17 at the tip of the body portion 13. The main body 16 is covered with a layer of cooling air and film-cooled.

Further, the cooling air guided into the hollow portion of the trailing edge portion 2 convects the inside of the main body portion 13 and is blown out from the cooling air blowing holes 3 at the trailing edge to the blade rows.

Here, the shroud 19 may be provided with holes 21 and the platform 18 may be provided with grooves 22, or both may be provided with holes.

As described above, in the present invention, the head 12 of the wing 1 is divided into the loose wing structural parts, that is, the main body 16, the platform 18, the shroud 19, etc., and the structural strength of the wing 1 is maintained in the latter, and the head Since the main body also supports the aerodynamic force exerted on 12,
Head 12 does not require structural strength.

In addition, the blade 1 may be deformed due to the thermal expansion of the turbine casing or its own thermal expansion, but the hole in the platform 18 for fitting the head 12 therein may 21, and the groove 22 of N1Niloud 19.
is larger than the head 12 and there is a gap between it and the vertical part 12, so even if the wing 1 deforms, this force will not be applied to the head 12.

That is, the wing 1 must be deformed, and the rear surface of the head 12 will be connected to the tip of the main body 16 and the holes 21 and grooves 22 due to the aerodynamic force.
Although it is in contact with the rear surface and does not receive any force from the wing 1, if the wing 1 deforms, the centers of the holes 21 and grooves 22 may shift or bend, and the main body 16 may protrude, causing the head 1
Force acts on 2.

Here, if there is no gap between the hole 21 and the groove 22, when the blade 1 deforms, all the force will also act on the head 12, but since there is a gap between the hole 21 and the groove 22, the blade 1 will deform. However, the head 12 moves within the hole 21 and groove 22 and no large force is applied.

Therefore, the gap between the hole 21 and the groove 22 needs to be larger than the amount of deformation of the blade 1, and specifically, it is sufficient if it is 0.1 to 0.15.

In addition, if the entire blade 1 expands due to thermal elongation, the holes 21
Since the center line of the groove 22 does not shift and the main body 6 does not protrude, the hole 21 and the groove 22 are
The gap needs to be taken into consideration.The reliability of the structural strength of the culm-juge-otsu nodame head 12 is insufficient. t
Therefore, ceramics, which could not be used to construct the blade 1 in the past, can be used.

The reason why the cap 20 is welded to the platform 18 all the way around is to prevent the mainstream gas from leaking out of the mainstream gas passage through the gap between the holes 21.

For this reason, in the present invention, the mainstream gas is dammed up, and the leading edge, or head, which is the highest temperature for the blade, is made of ceramic, which has higher heat resistance than metal. There is no need for film cooling by blowing cooling air out from the leading edge.

In addition, although the metal main body, platform, and shroud require cooling, the main body is not a part that gets particularly hot as a wing, and the tip of the main body is a ceramic head that blocks the heat of combustion gas. Cooling air flows through the cooling air passage between the head and the main body, preventing heat transfer from the head.
Since the temperature does not reach high temperatures and the tip of the main body is cooled, the amount of cooling air per collar is small.

On the other hand, since the side surface of the main body is exposed to combustion gas, cooling air 1 is blown out from the cooling air passage between the head and the main body to perform film cooling.

Here, since the head temperature of the platform and shroud is higher than before, cooling air is blown into the holes and grooves where the platform and shroud are attached to prevent heat transfer from the head.

In this way, if cooling of the head becomes unnecessary and the amount of cooling air used to cool the main body is reduced, the amount of cooling air required for the entire wing will be reduced.

Cooling air is blown into the mainstream gas after cooling the blades or for film cooling, but it mixes with the mainstream gas and cools it, so the smaller the amount of cooling air, the lower the average mainstream gas temperature. The thermal efficiency of the gas turbine is improved.

Furthermore, if the amount of cooling air is reduced, the amount of air compressed by the compressor that is extracted as cooling air is reduced, and this amount can be extracted as output, thereby improving gas turbine efficiency and output.

In addition, in the present invention, the cooling air for film cooling the main body is blown out from the cold air passage in the dividing plane between the head and the main body, and covers the side surface of the main body from its front end. For example, there will be no leading edge airflow, and air will be emitted from the side.

When performing film cooling from the leading edge of the blade, the dynamic pressure of the mainstream gas is applied to the blade front, so the pressure of the cooling air needs to be higher than this, and in order to maintain this pressure difference, the pressure of the mainstream gas system is Sometimes the pressure is intentionally lowered, but when blowing out from the trailing edge of the blade, the mainstream gas accelerates and the pressure decreases, so the pressure difference between the mainstream gas and the cooling air is maintained. There is no need to lower the pressure in the mainstream gas system, and the efficiency of the gas turbine improves accordingly.

In addition, in the present invention, the angle at which the dividing line between the head and the main body touches the blade row surface is set at a large angle, so that the cooling air blown out to the blade row through the cooling air passage in the dividing surface has a small space behind the blade. It will blow out at an angle.

Therefore, even if the pressure of the cooling air becomes higher than the pressure of the mainstream gas and is blown out vigorously, a cooling air layer is formed along the blade surface, and the cooling performance and aerodynamic performance are not impaired.

In addition, in the present invention, cooling air is no longer blown out from the leading edge of the blade, but instead is blown out from the side surface and trailing edge of the blade, and the amount of cooling air blown out to the blade cascade depends on the pressure difference between the cooling air and the mainstream gas. Since it is defined by the total cross-sectional area of the cooling air outlet, when blowing from the leading edge of the blade, the QU surface, etc. of the blade, there is a pressure distribution in the mainstream gas along the blade surface, and the cooling of each position of the snow Although the blade structure for controlling the amount of air blown out to a predetermined level is complex, the cooling air blown out from the leading edge of the blade, which receives the dynamic pressure of the mainstream gas, is no longer blown out, and the mainstream gas accelerates.
If the air is blown out from the blade side surface and the trailing edge of the blade where the pressure has decreased, the blade structure for blowing out a predetermined amount of cooling air in accordance with the pressure distribution of the mainstream gas along the blade surface becomes simple.

In addition, in the present invention, when the wing is divided into the head and the main body, the main body side is convex, so even if the direction of the aerodynamic force acting on the head changes, this force is effectively transferred to the main body. I can support you.

Further, the combination of the head and the main body is concave and convex, and it is possible to prevent the head from shifting from the main body, creating a step, causing separation of the mainstream gas flowing on the wing surface, and reducing aerodynamic performance.

In addition, even if the ceramic head is damaged for some reason, the main body has an airfoil shape with a convex tip, so a certain level of aerodynamic performance is maintained, and even if the head is damaged, It can be easily replaced.

[Brief explanation of drawings]

Figure 1-A, Figure 1-B, Figure 1-C, and Figure 1-D are plan sectional views of different conventional cooling type stationary blades, and Figure 1-E.
The figure is a side sectional view of another conventional cooling type cooling system, and Figure 2 is a diagram of a gas turbine system. FIG. 4 is a cross-sectional view of the stator vane of FIG. 3 along the camber line, and FIG. 5 is a cross-sectional view of several heads of the stator blade of FIG. 3. 1... Blade, 10... Turbine part of gas turbine, 1
1... Generator, 12... Head, 16... Main body,
16... Cooling air passage, 18... Platform, 19... Shroud, 20... Cap, 21...
...hole, 22...groove, 24...cooling air outlet. Applicant Makoto Ishizaka, Director General of the Agency of Industrial Science and Technology - 1-kl Figure 1-C Figure 1-E Figure 3

Claims (1)

[Claims] Separate the head of the gas turbine stator blade from the other stator blade structure,
The platform and shroud of the stationary vane are formed with holes or grooves, the upper and lower ends of the head are installed in the holes or grooves, and the inner surfaces of the holes or grooves are provided with cooling air. A stator blade for a gas turbine characterized by having pores for blowing out.