JPS59196902A - Stator blade of gas turbine - Google Patents

Abstract

PURPOSE:To reduce the cooling air demand and to improve the gas turbine efficiency by dividing a stator blade into a blade leading edge section and a blade main body which are made of ceramics, and by making the blade body hollow through which cooling air is routed. CONSTITUTION:A stator blade 1 is divided into a leading edge section 3 and a blade main body 2, which are made of ceramics. The blade main body 2 is made hollow, and cooling air passing through the hollow 4 is jetted out of holes 8 which are communicating with both sides of the blade main body 2 and a hole 9 which is communicated with the trailing edge. Since th blade leading edge section 3 is made of ceramics, there is no need to provide a hole for the cooling air jet in the leading edge, and the cooling air demand into the main flow can be reduced, resulting in the improvement in the gas turbine 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 become hotter and hotter in order to increase the performance and output of the turbines. 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 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 cooling air is introduced into the core and blown out to the inner surface of the blade from the blow-off hole at the tip of the core to locally increase the heat transfer coefficient and force cooling. As gas turbines become hotter, methods such as film cooling, which blows cooling air out of the blow-off holes at the leading edge of the guide and covers the outer surface of the blade with a layer of cooling air to block heat from high-temperature combustion gas, are being adopted. A combination of these cooling methods has now been used.

Here, the front part of the stationary blade is the part where high-temperature debris is dammed up, and it is the highest temperature part of the blade, so cooling this part is important.As the temperature of the gas turbine increases, film cooling is required. In addition, the amount of cooling air required to cool this area is also increasing. However, this cooling air is generally supplied by extraction from a compressor driven by the turbine section of a gas turbine.
As described above, when the amount of cooling air supplied increases, the power required for compressing the air with the compressor increases accordingly), which leads to a corresponding decrease in the efficiency of the gas turbine. Furthermore, as the amount of cooling air supplied increases as mentioned above, the amount of cooling air mixed with the mainstream gas also increases, and the average gas temperature of the mainstream gas decreases, which increases the cycle efficiency of the gas turbine. It will be a shame if it gets worse. The dynamic pressure is applied to the leading edge of the stator vane to stop the mainstream gas, but in order to blow out the cooling air completely, the pressure of the cooling live air must be greater than the pressure that includes the dynamic pressure of the mainstream gas. For this reason, a restrictor 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, the reduced pressure does not contribute to the work of the gas turbine, which inevitably leads to a decrease in the output of the gas turbine.

A stationary blade for a gas turbine according to the present invention that achieves the above object is characterized in that the plate head is separated from the blade body and is made of ceramic, and the blade body is formed hollow so that it is cooled by cooling air. It is something to do.

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 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 a plate head 3 made of ceramic on the leading edge side that dams up high-temperature gas. The wing body 2 and the plate 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. Furthermore, the extension lines of the boundary surfaces extending to the wing sides on both sides are at an acute angle α to the tangent to the wing sides, respectively.
It is designed to form α′.

Here, the range of the plate head ranges from the range where the mainstream gas is dammed up to the range where the heat transfer coefficient is high, and specifically, the range of the plate head is about 5 to 30% of the camber line length for light transmission.

On the other hand, inside the blade body 2, a cooling air supply source (not shown) (a compressor driven by a turbine section of a gas turbine) is provided.
Two hollow portions 4°5 communicating with each other are separated by a partition wall B.

One hollow part 4 communicates with cooling air blowing holes 7, 7,
Further, a cooling air blowing passage 8 provided along the boundary surface between the blade body 2 and the plate head 6 through the blowing holes 7, 7.
, 8, and open on both sides of the wing.

Therefore, the cooling air supplied to the hollow part 4 is blown out from the blow-off passages 8, 8 through the blow-off holes 7, 7 along both sides of the blade body 20, thereby film-cooling the blade body. The other hollow part 5 is a cooling air blowout hole 9.
It is designed to open at the trailing edge of the wing through. Therefore, the cooling air supplied to the hollow portion 5 convects the inside and is then blown out from the blow-off holes 9 toward the trailing edge of the blade.

- In the stator vane of the above-mentioned embodiment, the leading edge, which is the hottest among the stator vanes that dams up the mainstream gas, is formed by the head 6 made of ceramic, which has higher heat resistance than metal. Unlike the leading edge of a conventional stator vane, 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 shielded from the heat of the mainstream gas by the ceramic plate head 6, and by the blowout passage 8 provided at the interface between the two. Since heat transfer is prevented, the stationary blades of the conventional mechanism do not require a large amount of cooling air to cool the blade body 2 itself. As a result, the amount of cooling air mixed into the mainstream gas is reduced, suppressing the drop in average gas temperature, improving the efficiency of the gas turbine, and reducing the power loss of the compressor. This will further improve efficiency. In addition, the blowout passage 8 is not opened at the leading edge like in conventional stator vanes, but is opened at the side of the blade, so the dynamic pressure of the mainstream gas is directly applied to it, unlike in the case of conventional stator vanes. On the contrary, the speed of the mainstream gas increases and the pressure decreases, so in order to make it possible to blow out the cooling air, the pressure of the mainstream gas must be adjusted in consideration of the pressure difference with the mainstream gas. Since there is no need to take measures such as lowering the gas turbine, this also contributes to improving gas turbine efficiency.

Furthermore, ceramics have lower structural strength than metals, so it has traditionally been considered difficult to use them in cast turbine blades. Used for dog hunting, the structural strength of the wing is provided by the metal plate #2, and the aerodynamic force applied to the wing head 6 is also supported by the wing body 2, making it possible to use ceramics. did.

As described above, this makes it possible to further improve gas turbine efficiency.

As mentioned above, the stator blade of the gas turbine according to the present invention,
The wing head is separated from the wing body and made of ceramic, and the wing body is hollow and cooled by cooling air, reducing the amount of cooling air used.
The efficiency of gas turbines can be improved.

[Brief explanation of drawings]

The figure is a longitudinal sectional view showing a stationary blade of a cast turbine according to an embodiment of the present invention. 1... Stationary blade, 2... Wing body, 6... Wing head, 4,
5ha (e field ψ

Claims (1)

[Claims] A stationary blade for a gas turbine, characterized in that a blade head is separated from a blade body and is made of ceramic, and the blade body is formed hollow so that it is cooled by cooling air.