JPS59160006A - Stationary blade for gas turbine - Google Patents

Abstract

PURPOSE:To reduce the volume of cooling air for thereby improving a gas turbine in its operating efficiency, by arranging such that while a blade head portion is separated from a blade body and made of ceramics, a core is provided inside the hollow portion of blade body and a cooling air blow-off port is provided through the top end of core. CONSTITUTION:A plurality of stationary blades 1 arranged in an annular configuration comprises a blade body 2 made of heat resistant alloy and a blade head portion 3 made of ceramics and provided at the leading edge to prevent the flow of high temperature gas. These portions form their boundary face in such a configuration that the blade body side 2 is convexed. On the other hand, the interior of blade body 2 is made hollow 4 in which a core 5 is provided. The core 5 is communicated to a cooling air source and has a plenty of blow- off ports 6 provided at the top end thereof. The rear part of hollow portion 4 is communicated to the rear edge of blade via a cooling air blow-off port 7. In this manner, the volume of cooling air can be reduced and the absence of cooling air blow-off passage eliminates the need to lower the pressure of the main flow gas,thereby improving the gas turbine in its operating efficiency.

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 operate at higher temperatures in order to improve their performance and increase their output. Therefore, a major problem 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 method for cooling the vanes by configuring the stator vanes to be hollow, communicating the hollow part with a cooling air supply source, guiding the cooling air, and cooling the interior by convection. A method in which a core is provided inside the blade, and cooling air is guided into the core and blown out from the blow-off hole at the tip of the core to the inner surface of the blade to locally increase the heat transfer coefficient and perform forced cooling. As gas turbines become hotter, methods such as film cooling have been adopted, in which cooling air is blown out from blow-off holes in the front section, and the outer surface of the blade is covered with a layer of cooling air to block heat from high-temperature combustion gas. A combination of these cooling methods has now been used.

Here, the leading edge of the stationary blade is the part where high-temperature gas is dammed up and is the hottest part of the blade, so it is important to cool this part, and as the temperature of the gas turbine increases, the film Cooling is also used, and the amount of cooling air required to cool this part is also increasing. However, this cooling air is generally supplied by extraction from a compressor driven by the turbine section of the gas turbine, so the increase in the amount of cooling air supplied as described above means that the compressor cannot compress it. The required power increases,
This will cause a reduction in the efficiency of the gas turbine. Furthermore, as the amount of cooling air supplied increases as described above, the amount of cooling air mixed with the mainstream gas also increases, which lowers the average gas temperature of the mainstream gas, which in turn reduces the cycle efficiency of the gas turbine. will decrease. In addition, dynamic pressure is applied to the leading edge of the stator vane to block the mainstream gas, but in order to completely blow out the cooling air,
The pressure of the cooling air needs to be higher than the pressure including the dynamic pressure of the mainstream gas, and for this reason, the mainstream gas pressure may be lowered by providing a resistance or the like in the flow path on the mainstream gas side. 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.

SUMMARY OF THE INVENTION An 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.

A stationary blade for a gas turbine according to the present invention that achieves the above object has several heads that hold back high-temperature gas separated from the blade body and is made of ceramic, and the interface between these heads and the blade body is formed so that the blade body side has a convex surface. The blade body is formed to be hollow, and a core is provided in the hollow part, and a cooling air blowing hole is provided at the tip of the core toward the inner surface of the hollow part, and is characterized in that it is connected to a cooling air supply source.

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 them 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 main body 2 made of a heat-resistant alloy and several heads 6 made of ceramic on the leading edge side for damming up high-temperature gas. This wing body 2 and several heads 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. Here, the range of the head should be the range where the mainstream gas can be blocked or more, and specifically, it is appropriate to set it within about 10% of the length of the camber line.

On the other hand, the inside of the wing body 2 is formed to be a hollow part 4, and a core 5 is provided inside this hollow part 4.
is in communication with a cooling air supply source (not shown) (a compressor driven by a turbine section of a gas turbine). Core 5
A large number of blow-off holes 6 are provided at the tip of the hollow portion 4, and the blow-off holes 6 blow out cooling air locally toward the inner surface of the hollow portion 4. Further, the rear portion of the hollow portion 4 is formed into a trap so as to communicate with the trailing edge of the blade via a cooling air blowout hole 7.

Therefore, the cooling air supplied to the core 5 is blown out from the blow-off hole 6 at the tip toward the inner surface of the hollow part 4, locally increasing heat transfer and forcibly cooling the outer wall and inner wall of the core 5. 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 blow-off hole 7 at the trailing edge.

FIG. 2 shows a stationary blade according to another embodiment of the present invention.

In this embodiment, the rear end of the core 5 is joined to the inner wall of the hollow part 4 and communicates with the blowout hole 7, while the rear end of the hollow part 4 is connected to the outer surface of the blade body 2. There are many configurations in which blowout holes 9 are provided.

Therefore, in the stator vane, a part of the cooling air supplied to the core 5 is blown out from the rear blowing hole 7 to the rear end of the body 2, and the other part is blown out from the blowing hole at the tip. After locally forcing the inner surface of the hollow part 4 from 6, the side surface of the blade main body 2 is cooled while following the gap between the outer wall of the core 5 and the inner wall of the hollow part 4, and the rear blowout is cooled. Cooling is performed by blowing out through the holes 9 and forming a film layer of cooling air on the side surfaces of the wings.

In addition, in the stationary blades of each of the above-mentioned embodiments, FIG. 3 or 4
As shown in the figure, by providing a gap 10 at the interface between the multiple heads 6 and the blade body 2, heat transfer from the multiple heads 6 to the blade body 2 can be reduced.

In the above-mentioned stator vane, the leading edge, which holds back the mainstream gas and becomes the hottest part of the stator vane, is formed by the head 3 made of ceramic, which has higher heat resistance than metal. Unlike the leading edge of conventional stationary vanes, there is no need to provide cooling air blow-off holes for film cooling. On the other hand, the leading edge of the blade body 2 does not reach a high temperature, and its tip is blocked from the mainstream gas by several heads made of ceramic. The stationary vanes of this mechanism no longer require a large amount of cooling air. Moreover, the cooling of the blade body 2 is extremely efficient as the hot areas on the tip side are locally forcedly cooled through a large number of blow-off holes 6 provided at the tip of the hollow core 5. cooling is performed, making it possible to perform cooling with an even smaller amount of cooling air. 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.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 consideration to enable cooling air to be blown out. However, since there is no need to take measures such as taking the trouble to lower the mainstream gas pressure, this also contributes to improving gas turbine efficiency.

In addition, in the above-mentioned stationary blade, since no cooling air blowing hole is provided at the leading edge that receives the dynamic pressure of the mainstream gas, the blade structure for blowing out the cooling air according to the pressure distribution of the mainstream gas is It can be simpler than the conventional stator vane, which blows air from the front part.

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 wing body 2 is made of metal to provide strength, and the aerodynamic force acting on the head 3 is supported by the wing body 2, making it possible to use ceramics. Along with this, as mentioned above, it is possible to further improve the gas turbine efficiency.

Moreover, since the ceramic heads 3 form a boundary surface with a convex shape on the wing body 2 side, even if the direction of the force of the mainstream gas acting on the ceramic heads 3 changes, this force can be supported by the main body 2. In addition, several heads 3 and wing bodies 2
Since this is a combination of concave and convex surfaces, it is possible to prevent a difference in level caused by a gap between the two, which would cause the gas flow to separate from the blade surface and degrade aerodynamic performance. Also, even if the ceramic head is damaged for some reason, the wing body 2. Since the distal end surface is convex, a certain level of aerodynamic performance can be maintained and it can be easily replaced.

As mentioned above, the stator blade of the gas turbine according to the present invention has the following features:
The several heads that hold back the mainstream gas are separated from the blade body and are made of ceramic, and the boundary surface between the several heads and the blade body is formed so that the side of the blade body is convex. A core is provided in the hollow part, a hole is provided at the tip of the core for blowing cooling air toward the inner surface of the center diameter part, and this core is communicated with a cooling air supply source, so that cooling air is The amount can be reduced, and since the configuration does not provide a blowout passage for cold air, there is no need to lower the pressure of the main stream, and the efficiency of the gas star cell 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, FIG. 2 is a longitudinal sectional view of a stator vane according to another embodiment of the invention, and FIGS. FIG. 7 is a sectional view of a main part of a stator blade according to another embodiment. 1... Stationary blade, 2... Wing body, 3... Several heads, 4...
...Hollow part, 5...core, 6,7...blowout hole. Applicant Makoto Ishizaka, Director General of the Agency of Industrial Science and Technology - Figure 11A ◇ / Figure 3 Figure 4

Claims (1)

[Claims] The cap is separated from the wing body and is made of ceramic, the boundary surface between the wing head and the wing body is formed so that the wing body side is convex, the wing body is formed hollow, and a A stationary blade for a gas turbine, characterized in that a core is provided, and a hole for blowing cooling air toward the inner surface of a hollow portion is provided at the tip of the core.