JPS59160004A - Stationary blade for gas turbine - Google Patents

Abstract

PURPOSE:To improve a gas turbine in its operating efficiency, by arranging such that while the part of blade head where a heat transmission rate is high is separated away from a blade body, and formed with a ceramics, the blade body is made hollow and cooled by means of a cooling air for thereby lowering the volume of cooling air. CONSTITUTION:A plurality of stationary blades 1 is arranged in an annular configuration. In this case, the stationary blade 1 comprises a blade body 2 made of heat resistant alloy and the ceramics head portion of blade provided at a forward end for preventing the flow of main stream gas. These elements 2, 3 form their boundary in such a configuration that the blade body 2 side may take a convexed shape. On the other hand, the interior of blade body 2 is made as a hollow portion 4. The hollow portion 4 communicates to a cooling air source, having a blow-off port 5 provided at the rear end thereof to open towards the rear edge of stationary blade 1. In consequence, a cooling air supplied to the hollow portion 4 is blown into a high temperature gas through a blow-off port 5, after it has cooled the interior of blade body 2 through a convection. In this manner, the volume of cooling air can be reduced, eliminating the need to lower the pressure of the main stream gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to stator blades used in high-temperature gas turbines and the like.

In recent years, gas turbines have tended to become increasingly hotter in order to improve their performance and increase their output. Therefore, a major technical issue is how to maintain the strength of turbine blades under such high temperature gas conditions. In order to solve these problems, we have developed a hollow stator vane as a way to cool the vane.
A method in which the hollow part is communicated with a cooling air supply source and the cooling air is guided to cool the inside by convection.A core is provided in the hollow part of the blade, and cooling air is guided into the core for blowing out the tip of the core. A method in which cooling air is blown into the inner surface of the blade through the holes to locally increase the heat transfer coefficient and forced cooling. Cooling air is guided into the hollow part of the blade and is blown out from the blow-off holes in the leading edge, thereby cooling the outer surface of the blade. Film cooling methods have been adopted in which the gas turbine is covered with layers to block heat from the high-temperature combustion gas, and as gas turbines become hotter, these cooling methods have come to be used in combination.

Here, the front edge of the stationary blade is the part where high-temperature gas is dammed up and is the hottest part of the blade, so cooling this part is important, and as the temperature of the gas turbine increases, Film cooling is also used, and the amount of cooling air required to cool this area is also increasing. However, since this cooling air is generally supplied by extraction from a compressor driven by the turbine section of a gas turbine, the increase in the supply amount of cooling air as described above means that
The power required for compression by the compressor increases accordingly, leading to a corresponding decrease in the efficiency of the p-turbine.

Furthermore, as mentioned above, the supply amount of cooling air increases, and the amount of cooling air mixed with the mainstream gas increases, which lowers the average gas temperature of the mainstream gas, which reduces the gas turbine cycle. This will result in a decrease in efficiency. In addition, since the leading edge of the stationary blade dams up the mainstream gas, its dynamic pressure is applied, but in order to blow out the cooling air completely, the pressure of the cooling air must be greater than the pressure including the dynamic pressure of the mainstream gas. Therefore, a restriction resistor or the like is sometimes provided in the flow path on the mainstream gas side to lower the mainstream gas pressure. However, in this case, since the reduced pressure does not contribute to the work of the gas turbine, a reduction in the output of the gas turbine is inevitable in this case as well.Objective of the Invention The object of the present invention is to provide a stationary blade for a gas turbine □ that solves the above-mentioned problems and makes it possible to improve the efficiency of the gas turbine.

The stator vane for a gas turbine according to the present invention that achieves the above object is configured to separate the high heat transfer coefficient range of the blade head from the blade body, and to make the boundary between the blade head and the blade body with the blade body side facing away from the blade body. The wing body is characterized in that it has a convex surface or a surface perpendicular to the camber line, and the wing body is formed hollow so that it is cooled by cooling air.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 1 shows a stator blade of a gas turbine according to an embodiment of the present invention. In this figure, reference numeral 1 indicates stationary blades, and a plurality of these vanes are arranged in a ring shape.

High-temperature gas is supplied to the stator vanes arranged in this manner as shown by the arrows.

The stationary blade 1 is composed of a blade body 2 made of a heat-resistant alloy and a blade head 6 made of ceramic on the leading edge side that dams up mainstream gas. The wing body 2 and the wing head 6 are
The boundary surface is formed in such a shape that the sides are convex. The cross-sectional line forming the boundary surface of this convex surface may be a curved line or a broken line. The length of the ceramic blade head 2 is set within a range that provides a high heat transfer coefficient, and specifically, it is appropriate to set the length to within about 30% of the cantilever line length.

On the other hand, the inside of the blade body 2 is formed to be a hollow part 4, and this hollow part 4 communicates with a cooling air supply M#i (a compressor driven by a turbine part of a gas turbine) (not shown). . The rear portion of the hollow portion 4 opens to the trailing edge of the stationary blade 1 through a blowout hole 5 . Therefore, the cooling air supplied to the hollow portion 4 convectively cools the blade body 2 inside, and then is blown out into the high-temperature gas from the blow-off holes 5 at the rear.

Note that the boundary surface between the wing body 2 and the wing head 3 is formed in such a shape that the wing body 2 side is convex in the embodiment shown in FIG.
As shown in FIG. 2, it may be formed in a shape perpendicular to the camber line L.

FIG. 3 shows another embodiment of the invention. In this embodiment, a core 6 is provided in the hollow portion 4 of the blade body 2, and a large number of blowout holes 7 are provided at the tip of the core 6. The cooling air is locally blown out toward the inner surface of the hollow portion 4.

Therefore, the cooling air supplied to the core 6 is blown out from the blow-off hole 7 at the tip toward the inner surface of the hollow part 4, locally increasing heat transfer and being forcedly cooled, and then between the outer wall of the core 6 and the hollow part 4. The side surface of the blade body 2 is cooled while passing through the gap 8 between the blade body 2 and the inner wall of the blade body 2, and is blown out into the hot gas from the blowout hole 5 at the trailing edge.

FIG. 4 shows a stationary blade according to still another embodiment of the present invention.

In this embodiment, the rear end of the core 6 is joined to the inner wall of the hollow part 4 and communicates with the blowout hole 5, while the rear end of the hollow part 4 is provided with a blowout which exits to the outer surface of the blade body 2. It has a configuration in which a use hole 9 is provided. Therefore, in this stationary blade, a part of the cooling air supplied to the core 6 is blown out from the rear blowing hole 5 to the rear end of the main body 2, and the other part is blown out from the blowing hole 7 at the tip to the hollow part. After the inner surface of the wing 4 is forcedly cooled, it is blown out from the blow-off hole 9 at the rear to form a film layer of cooling air on the side surface of the wing. In addition, as shown in FIG. 5, blowout passages 11, 11 are opened on both sides of the blade along the interface between the blade head 6 and the blade body 2.
are provided, and the blow-off passages 11 and 11 are respectively connected to the blow-off holes 1.
By communicating with the hollow portion 4 through 2.12, the side surface of the blade body 2 can be film-cooled by the cooling air blown out from the blow-off passages 11, 11.

In the stator vanes of each of the above-described embodiments, the leading edge portion, which is the highest temperature among the stator vanes, has a high heat transfer coefficient, and is formed by the head 6 made of ceramic, which has higher heat resistance than metal. Unlike the leading edge of conventional stator vanes, there is no need to provide cooling air blow-off holes or film cooling on this leading edge. On the other hand, the leading edge of the blade main body 2 does not reach a high temperature, and the area with a high heat transfer coefficient at the tip is blocked from the heat of the mainstream gas by the ceramic blade head 6. Since there is little heat transfer between the airfoils, conventional stationary blades no longer require a large amount of cooling air to cool the blade body 2 itself, and convection cooling inside the hollow space is sufficient for cooling. Become. As a result, the amount of cooling air mixed into the mainstream gas is reduced, suppressing the drop in average gas temperature, and improving the efficiency of the gas turbine.In addition, the power required to drive the compressor is also reduced, making the gas turbine more efficient. This will further improve the results. In addition, unlike conventional stationary vanes, there is no need to provide a blowout hole on the leading edge where the dynamic pressure of the mainstream gas directly acts, so the pressure difference with the mainstream gas is taken into account to enable blowing out of cooling air. Since there is no need to take measures such as taking the trouble to lower the pressure of the mainstream gas, this also contributes to improving the efficiency of the gas turbine.

In addition, in the above-mentioned stationary blade, the cooling air blowout hole is not provided at the leading edge that receives the dynamic pressure of the mainstream gas. The blade structure can be simpler than the conventional stationary blade in which one blow is ejected from the leading edge.

Furthermore, ceramic has inferior structural strength compared to metal, so it was previously considered difficult to use it for the stationary blades of gas turbines. The blade body 2 is made of metal and has strength, and the aerodynamic force applied to the head 6 is also supported by the blade body 2, making it possible to use ceramics. If the wing head 6 is set in a range where the heat transfer coefficient is high, it will inevitably be about 1/3 the size of the entire wing, increasing its rigidity and making it less likely to break. Conversely, although the rigidity of the blade body 2 decreases, it is sufficient to use a segmented blade structure in which a plurality of blades 1 are combined into one set.

Moreover, since the ceramic blade head 6 and the blade body 2 form an interface with a convex shape on the blade body 2 side as shown in FIG. 1, the mainstream gas acting on the blade head 6 is Even if the direction of the force changes, the force can be supported by the main body 2, and since the R head 6 and the wing main body 2 form a four-sided combination,
It is also possible to prevent misalignment between the two (such as a step forming, causing the gas flow to separate from the blade surface and deteriorating aerodynamic performance).

As described above, the stationary blade of the gas turbine i according to the present invention separates the high heat transfer coefficient range of the blade head from the blade main body and is made of ceramic, and the interface between the blade head and the blade main body is Since the wing body side is made to have a convex surface or a surface perpendicular to the camber line, and the wing body is formed hollow and cooled by cooling air, the amount of cooling air can be reduced. Since the cooling air outlet is not provided at the leading edge of the blade, there is no need to lower the pressure of the mainstream gas, and the efficiency of the gas turbine can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a stator vane of a gas turbine according to an embodiment of the present invention, and FIGS. 2, 3, and 4 are longitudinal sectional views of stator vanes according to other embodiments of the present invention, FIG. 5 is a sectional view of a main part of a stationary blade according to still another embodiment. 1... Stationary blade, 2... Wing body, 6... Wing head, 4...
... Hollow part, 5 ... Blowout hole, 6 ... Core. Applicant Makoto Ishiita, Director General of the Agency of Industrial Science and Technology - Figure 1 Figure 3

Claims (1)

[Claims] The area where the heat transfer coefficient is high in the wing head is separated from the wing body and is made of ceramic, and the boundary surface between the wing head and the wing body is made convex on the wing body side or perpendicular to the camber line. A stationary blade for a gas turbine, characterized in that the blade main body is formed hollow and is cooled by cooling air.