JPS6360203B2 - - Google Patents

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, a method of cooling the blades has been adopted, and the use of highly heat-resistant ceramics, etc., as the material for the blades is being considered, but this ceramic has extremely high heat resistance. However, due to their low structural strength and lack of reliability, they have not yet been put into practical use as turbine blades.

The purpose of the present invention is to solve the above-mentioned problems,
The purpose of this invention is to provide a stator vane for a gas turbine that makes it possible to use materials such as ceramics, which have high heat resistance but low structural strength, for the blades, thereby making it possible to improve the efficiency of the gas turbine. be.

A stationary blade for a gas turbine according to the present invention that achieves the above object has a blade head separated from a blade main body, and the blade head made of a material with high heat resistance but low structural strength,
The boundary line is formed so that the blade body side becomes a convex portion, and cooling air blowing holes are provided on the boundary surface.

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

The figure shows a stator blade of a gas turbine according to an embodiment of the present invention. In this figure, reference numeral 1 denotes stationary blades, a plurality of which 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 includes a blade body 2 made of a general heat-resistant alloy with high structural strength, and a blade head 3 on the leading edge side made of ceramic, which has significantly higher heat resistance than the alloy of the blade body but has lower structural strength. It consists of The boundary surface between the wing body 2 and the wing head 3 has a convex shape on the wing body 2 side. The cross-sectional line forming the boundary surface of this convex surface may be a curved line or a broken line. Therefore, in such a combination, the extension lines of the boundary surfaces extending to both side surfaces of the blade form acute angles α and α', respectively, with respect to the tangent to the side surfaces of the blade. The length of the ceramic wing head 2 is preferably within about 10% of the camber line length.

On the other hand, inside the blade body 2, two hollow parts 4 and 5 are formed separated by a partition wall 6 and communicated with a cooling air supply source (not shown) (a compressor driven by a turbine section of a gas turbine). There is. One hollow part 4 communicates with cooling air blow-off holes 7, 7, and is further provided along the boundary line between the blade body 2 and the blade head 3 via the blow-off holes 7, 7. It communicates with the cooling air blowing passages 8, 8, and opens on both side surfaces of the blade, respectively. Cooling air is blown out from this blowing passage 8, and film cooling is performed by covering the outer surface of the blade with a layer of cooling air to isolate heat from the high-temperature sintered gas. Also, the other hollow part 5
is opened at the trailing edge of the blade through a cooling air blowout hole 9. Therefore, this hollow part 5
The cooling air supplied to the blade convects the inside and is then blown out from the blowout hole 9 toward the trailing edge of the blade.

Now, as mentioned above, it was previously considered difficult to use ceramics for gas turbine blades because of their inferior structural strength compared to ordinary metals.
In the stationary blade described above, this ceramic is used only for the head 3, and the structural strength of the blade is supported by the blade body 2, and the aerodynamic force applied to the head 3 is also supported by the blade body 2. This makes it possible to use ceramics for stator blades. Moreover,
The ceramic wing heads 3 are assembled so that the side of the wing body 2 is convex, so even if the direction of the pressure of the mainstream gas acting on the wing head 3 changes, this force can be supported by the body 2. can. In addition, since the wing head 3 and the wing body 2 are a combination of unevenness, it is possible to prevent the gap between the two from forming a step, causing the gas flow to separate from the wing surface, and reducing aerodynamic performance. can. Furthermore, even if the ceramic head is damaged for some reason, the boundary surface of the wing body 2 is convex, so a certain level of aerodynamic performance can be maintained and it can be easily replaced. ing. Furthermore, if the extension lines of the boundary surfaces that extend to the side surfaces of both blades are made at acute angles to the tangents to the side surfaces of the blades, even if the pressure of the cooling air becomes greater than the pressure of the mainstream gas and it blows out forcefully. Even if this occurs, a good film layer of cooling air will be formed on the side surfaces of the wing, and cooling performance and aerodynamic performance will not be impaired.

In addition, when the blade main body is hollow and is cooled by cooling air as in the above embodiment, the leading edge, which is the highest temperature among the stationary blades that hold back the mainstream gas, has a heat-resistant Since the head 3 is made of high-quality ceramic, there is no need to provide cooling air blowing holes in the leading edge of the vane to cool the film, unlike conventional leading edge film-cooled vanes. Further, the blade main body 2 having the configuration of the above embodiment does not reach a higher temperature than the leading edge, and the tip thereof is shielded from the heat of the mainstream gas by the ceramic blade head 3, and the blade body 2 is provided at the interface between the two. Since heat transfer is also prevented by the blow-off passage 8, a large amount of cooling air is not required to cool the blade body 2 itself, as compared to the conventional leading edge film-cooled stationary blade. 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 improve the results. In addition, the blowout passage 8 is not opened at the leading edge of the stator blade, but is opened at the side of the blade, so that the dynamic pressure of the mainstream gas does not directly act on it, as in the case of conventional stator blades. This also eliminates the need to take measures to lower the mainstream gas pressure in consideration of the pressure difference with the mainstream gas in order to enable the blowing of cooling air, which also helps improve gas turbine efficiency. It will contribute.

In addition, in the stator vane of the example, since no holes for blowing out cooling air are provided at the leading edge that receives the dynamic pressure of the mainstream gas, the blade structure is designed to blow out the cooling air according to the pressure distribution of the mainstream gas. , it can be made simpler than the conventional stator vane which blows air from the leading edge.

The above embodiment describes the case where ceramic is used as the heat-resistant material for the wing head, but there are also other materials such as tungsten, which has very high heat resistance but poor structural strength. It is also possible to apply the following materials.

As described above, in the stationary blade of a gas turbine according to the present invention, the blade head is separated from the blade main body, the blade head is made of a material with high heat resistance but low structural strength, and the boundary surface between the blade head and the blade main body is made of a material having high heat resistance but low structural strength. Since the sides are formed with convex surfaces, even materials with low structural strength can be used effectively as the structure of gas turbine blades, allowing effective use of heat resistance, thereby making it possible to improve the efficiency of gas turbines. do.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view showing a stationary blade of a gas turbine according to an embodiment of the present invention. 1... Stationary blade, 2... Wing body, 3... Wing head, 4, 5...
Hollow part, 7, 9...Blowout hole, 8...Blowout passage.

Claims (1)

[Claims] 1 The wing head is separated from the wing body, and the wing head is made of a material with high heat resistance but low structural strength, and the boundary surface is formed so that the wing body side is a convex surface, and the boundary surface is formed with a convex surface. A stationary blade for a gas turbine characterized by having cooling air blowing holes.