JPS61149503A - Turbine blade - Google Patents

Abstract

PURPOSE:To enhance the cooling efficiency of a turbine blade, by jetting a cooling agent, etc. from a cylinder fitted into a blade body and having a plurality of holes, into a cooling fluid passage formed between the blade body and the cylinder, and by forming the inner wall surface of the blade body as a liquid drop trapping member. CONSTITUTION:A liquid cooling agent fed from a liquid cooling inlet port 24 into a liquid cooling agent passage 22a is jetted through a plurality of holes 26a, 26b formed in the side wall and top wall of an inner cylinder, into a cooling air passage 23. At this time a part of the cooling agent flushes and it turned into steam while the remaining part of the cooling agent is turned into liquid drops and is stuck on a wick structure 28 or small protrusions. Meanwhile, cooling air flows into a cooling air inlet port 25, and after flowing through the cooling air passage 23, flows out from a blow-out port 27 in the trailing edge section of the turbine blade 21. Further, when cooling air flows through a cooling air passage 23, the above-mentioned liquid drops are evaporated. Accordingly, a large cooling effect may be obtained.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to turbine blades, and more particularly to turbine blades suitable for use in gas turbine first stages exposed to high temperatures.

(Technical background of the invention and its problems) The most effective way to increase the thermal efficiency of a gas turbine is to increase the combustion gas temperature at the turbine inlet.

However, current heat-resistant alloys suffer from thermal stress, high-temperature oxidation, and hot colloids that occur during high-temperature turbine operation.
It does not have sufficient ability to withstand high temperatures, and there is a limit to the ability to increase the inlet gas temperature. Therefore, various turbine cooling blades have been proposed as means for increasing the inlet gas temperature as much as possible.

7 and 8 show typical air-cooled turbine blades. The interior of the turbine blade 1 is divided by a partition wall 2 into a leading edge side and a trailing edge side.

A large number of fins 3, baffles 4, and air blowing holes 5 are provided inside the blade on the leading edge side. A slit 6 is provided at the trailing edge, and the inner surfaces of the wing walls are connected by bin fins 7. Cooling air is supplied from the frontage 8 of the blade root and blows out from the hole 5 to form a film of air for cooling. At the trailing edge of the blade, air blown out downstream from the rear of the blade through the slit 6 performs convection cooling. In the return 70 part 9, three rows of return flow are performed from the trailing edge of the blade to the leading edge, and at the same time, convection cooling is performed, and at the same time, cooling is performed by a film formed by the air blown out from the hole provided in the blade abdomen. will also be held.

However, in a turbine blade with such a configuration,
The pressure on the blade vent side is higher than that on the blade dorsal side, and ash and impurities in the combustion gas are likely to adhere to the blade, and there is a risk that the air blowing holes may be blocked. Further, since the pressure distribution on the outer surface of the turbine blade is not uniform, the amount of air blown out from the joint holes is different, and the temperature distribution on the blade surface tends to be uneven. Furthermore, in the return flow type cooling system, while the cooling air flows along the arrow in FIG. 7, the temperature rises and the air flow rate gradually decreases because air is blown out. Therefore, the cooling performance gradually decreases and the blade surface temperature becomes uneven.

As described above, there is a limit to increasing the gas turbine inlet temperature using only air cooling, and proposals have been made for methods such as steam cooling and water cooling.

FIGS. 9 and 10 show examples of turbine-cooled blades that use both air cooling and water cooling.

A large number of pores 10 are bored on the blade vent side from the blade root end face along the wall surface toward the blade top, and communicate with the hollow part, that is, the cooling air flow path 11 on the blade top side. The cooling water passes through the pores 10, flashes into steam at the point where it communicates with the air flow path 11, and flows out of the garden together with the cooling air from the air outlet 12.

In general, many cooling blades that use water have a large number of holes near the blade surface through which cooling water flows. However, in this type of water cooling, it is difficult to provide pores on the thin trailing edge side of the blade. Further, even in blades that are highly twisted three-dimensionally, there is a problem in that it is difficult to fabricate such pores through which cooling water passes.

[Purpose of the invention]

The present invention solves the above-mentioned problems of conventional cooling blades, and provides a turbine blade that does not have air blowing holes in the blade abdomen, provides a good cooling effect over the entire blade surface, and is easy to process. is intended to provide.

(Summary of the Invention) In order to achieve the above object, the present invention provides an inner cylinder in a hollow turbine blade body, forms a cooling air flow path between the blade body and the inner cylinder, and wicks the inner surface of the blade body. The projecting surface of the structure or small protrusions is used to flash the liquid coolant or gas-liquid two-phase coolant from the holes in the inner cylinder wall into the cooling air flow path, and the remaining droplets attached to the wick structure or protrusions are It is characterized in that it evaporates.

[Embodiments of the invention]

Hereinafter, embodiments of a turbine blade according to the present invention will be described with reference to the drawings.

In FIGS. 1 to 3, a hollow turbine blade body 21
An inner cylinder 22 having a substantially similar outer shape and small size to the blade body is held inside the blade body, and a cooling air flow path 23 is formed between the body 21 and the inner cylinder 22. The base of the inner cylinder 22 opens inside the blade root of the blade body 21 and forms an inlet 24 for liquid coolant.
The space between the inner surface of the blade root portion of the blade body 21 and the outer surface of the base portion of the inner cylinder 22 serves as a cooling air inlet 25. A large number of holes 26a are diagonally formed in the side wall of the inner cylinder 22 at substantially the same pitch over the entire surface, and similar holes 26a are formed in the top wall of the inner cylinder 22.
b are perforated in the vertical direction over the entire surface.

The trailing edge portion 21b of the wing body is provided with an outlet 27 for blowing out the above-mentioned cooling air to the outside of the garden. Also,
A wick structure 2B for holding droplets is provided on the inner wall surface of the wing body 21 and the inner wall surface of the top lid 21a.

In addition to the wick structure, these inner wall surfaces may have a structure that can hold droplets on the wall surface, for example, a large number of small protrusions protruding from the wall surface to form an uneven wall surface, or a large number of tongue pieces may be provided on the wall surface. It's fine.

Since the present invention is configured in this way, the liquid coolant sent from the liquid coolant inlet 24 to the liquid coolant flow path 22a flows through the numerous holes 26a bored in the inner cylinder side wall and top wall.
, 26b to the cooling air flow path 23, respectively.

At this time, part of the liquid coolant flashes and becomes vapor, and the remaining part becomes liquid droplets 29 that adhere to the wick structure 28 or the small protrusions as shown in FIG. On the other hand, cooling air flows in from the cooling air inlet 25 and flows through the cooling air flow path 23 . The air flows out from the air outlet 27 at the trailing edge of the blade to the blade body. The temperature of this cooling air is generally several hundred degrees in high-temperature gas turbines, so when the cooling air flows through the cooling air flow path 23, droplets 2 adhere to the wick structure 28 or the small protrusions.
Evaporate 9. If the airfoil inner wall is a wick structure,
The droplets ejected from the holes in the inner cylinder and attached to the wick structure are uniformly distributed on the inner wall of the blade body due to capillary action, so that they evaporate uniformly from the inner wall. Although this wick structure has a structure extending in the chord direction in this embodiment, it may have a structure extending in the blade span direction, or may have a structure that is a combination of both. Moreover, the coolant spouted from the inner cylinder may be not only a liquid but also a gas-liquid two-phase coolant containing an appropriate amount of droplets.

5 and 6 show another embodiment, in which the inner cylinder is composed of three inner cylinders 30, 31, 32 at the front edge, center, and rear edge, Coolant channels 30a, 31a, and 32a are provided inside each, and coolant blowing holes are provided in the side wall and the top wall. These inner cylinders 30, 31.3
2 are connected by a support plate 33 and supported within a wing body 34. Further, the cooling air flow path between the central inner cylinder 31 and the inner wall of the blade body 34 is defined by a partition plate 36 provided with at least one hole 35 on the leading edge side 37 and the trailing edge side 38, as shown in FIG.
It is divided into two parts. In this embodiment, since this partition plate 36 is provided, if cooling air is supplied to the cooling air passage 37 on the leading edge side, the cooling air passes through the hole 35 provided in the partition plate 36, and the cooling air on the trailing edge side It reaches the flow path 38 and flows out to the blade body through the cooling hole 39. In this example, a kind of cooling air duct is formed by the inner cylinder and the blade body wall, and a large cooling effect can be performed with a smaller amount of cooling air. In addition, the wick structure 4
The above-mentioned real X11 has 0 on the inner wall of the airfoil! This is the same as example i.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, a wick structure or a protrusion is provided in the cooling air flow path, and a liquid coolant or a gas-liquid two-phase coolant is introduced into the cooling air flow path. As the cooling air flows through the cooling air flow path, droplets attached to the wick structure or protrusions are evaporated, resulting in a large cooling effect. With a wick structure, the droplets are evenly distributed on the inner wall of the blade due to capillary action, allowing for more uniform cooling over the entire blade surface.Moreover, it is easy to process.In addition, the cooling air flow If a partition plate is provided in the passage, a large cooling effect can be obtained with a smaller amount of air.Therefore, the turbine inlet gas temperature can be increased, and thermal efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of a turbine blade according to the present invention, FIG. 2 is a vertical cross-sectional view taken along the line ■-■ in FIG. 1, and FIG.
The figure is a perspective view of the inner cylinder, FIG. 4 is a partially enlarged vertical sectional view taken along the rV-rV line in FIG. 1, FIG. 5 is a cross-sectional view showing another embodiment of the present invention, and FIG. 5 is a partially enlarged sectional view taken along the line Vl--Vl, FIG. 7 is a vertical sectional view showing an example of a conventional air-cooled blade, FIG. 8 is a cross-sectional view taken along the line FIG. 9 is a cross-sectional view showing an example of a conventional cooling blade that uses both air and water, and FIG. 10 is a vertical cross-sectional view taken along the line X--X in FIG. 9. 21.34...Turbine blade, 22.30.31°32
... Inner cylinder, 23, 37. 38 ... Cooling air flow path, 2
2a, 30a, 31a, 32a...liquid coolant flow path,
26a, 26b...hole, 28...wick structure,
35...hole, 36...partition plate. Applicant's agent Kiyoshi Inomata Figure 9 Figure 10

Claims (1)

[Claims] 1. In a hollow turbine blade having a cooling flow path inside, one or more cylindrical bodies with a large number of holes bored in the wall surface are inserted into the blade body, and this cylindrical body and the above-mentioned blade bodies are connected to each other. A cooling air flow path is formed between the wing body and the inner wall, and a liquid coolant or a gas-liquid two-phase coolant is blown from the cylinder body to the cooling air flow path, and the inner wall surface of the wing body is used as a droplet holder. A turbine blade characterized by: 2. The turbine blade according to claim 1, wherein the droplet holder is a wick structure. 3. The turbine blade according to claim 1, wherein the droplet holder comprises a large number of small protrusions.