JPS6359003B2 - - 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, 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 are adopted, in which cooling air is blown out from the blow-off holes in the leading edge of the blade, and the outer surface of the blade is covered with a layer of cooling air to isolate heat from the high-temperature combustion gases. A combination of methods has 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 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, 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 has to compress the air accordingly. The required power increases, leading 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, which lowers the average gas temperature of the mainstream gas, which improves the cycle efficiency of the gas turbine. This will result in a decline. In addition, the dynamic pressure is applied to the leading edge of the stator vane to hold back the mainstream gas, but in order to blow out the cooling air completely, the pressure of the cooling air must be greater than the pressure that includes the dynamic pressure of the mainstream gas. Therefore, in some cases, a restrictor or the like is 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.

The purpose of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a stator blade for a gas turbine that 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 a blade head for damming mainstream gas that is separated from a blade body and is made of ceramic, and this boundary surface is a convex surface on the blade body side, and the boundary surface The extension line of the blade is formed so as to form an acute angle with the tangent to the side surface of the blade, and a cooling air blowing passage is provided along this boundary surface, and this blowing passage has a blowing hole in the hollow part of the blade main body. This is characterized in that the hollow portion 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 body 2 made of a heat-resistant alloy and a blade head 3 made of ceramic on the leading edge side for holding back high-temperature gas. The wing body 2 and the wing head 3 form a boundary surface in such a shape that the wing body 2 side is 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 shaped like α′. Here, it is appropriate that the range of the head is within the range where the mainstream gas can be dammed up or beyond, and specifically within about 10% of the length of the camber line.

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 surface 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. As shown in FIG. 2, this blowout passage 8 is formed by a large number of grooves carved along the convex surface of the blade body 2 side.
Therefore, the cooling air supplied to the hollow part 4 is
The air is blown out from the blow-off passages 8, 8 through the blow-off holes 7, 7 to both side surfaces of the blade body 2, thereby cooling the blade body 2 as a film. The other hollow portion 5 opens at the trailing edge of the blade through a cooling air blowout hole 9. 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.

Note that the blowout passage 8 provided between the blade body 2 and the blade head 3 is formed by carving a large number of grooves on the blade body 2 side in the above-mentioned FIG.
As shown in the figure, a large number of partition plates 30 may be formed by protruding from the wing body 2. Note that the amount of cooling air blown out from the blowout passage 8 to both side surfaces of the blade body 2 is determined by the total cross-sectional area of the blowout holes 7.

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

In this embodiment, a core 10 is provided in the hollow part 4 on the tip side, and the inside of the core 10 is communicated with a cooling air supply source, and the tip of the core 10 has a large number of blowing holes. 11 are provided.
Therefore, in this stationary blade, cooling air is blown toward the inner surface of the hollow part 4 from the blowout hole 11 at the tip of the core 10 to locally increase heat transfer and perform forced cooling. Make it. In this stationary blade, a blowout hole 12 for blowing out cooling air from the hollow portion 4 to the side surface of the blade is provided so as to open further downward.

In the stator vanes of each of the above-described embodiments, the leading edge, which is the highest temperature among the stator vanes that hold back the mainstream gas, has a head 3 made of ceramic, which has higher heat resistance than metal.
Therefore, unlike the leading edge of a conventional stationary blade, there is no need to provide cooling air blowing holes in the leading edge for film cooling. On the other hand, the blade body 2 does not reach as high a temperature as the leading edge, and its tip is shielded from the heat of the mainstream gas by the ceramic blade head 3 and by the blowout passage 8 provided at the interface between the two. Since heat transfer is prevented, a large amount of cooling air is not required to cool the blade body 2 itself, as compared to the stationary blade of the conventional mechanism. As a result, the amount of cooling air mixed into the mainstream gas is reduced, suppressing a drop in average gas temperature, and improving the efficiency of the gas turbine. Furthermore, the power required to drive the compressor is also reduced, further improving the efficiency of the gas turbine. In addition, the blowout passage 8 is not opened at the leading edge like in conventional stator blades, but is opened at the side of the blade, so the dynamic pressure of the mainstream gas acts on it as in the case of conventional stator blades. On the contrary, the speed of the mainstream gas increases and the pressure decreases, so in order to make it possible to blow out cooling air, the pressure of the mainstream gas is deliberately lowered to take into account the pressure difference with the mainstream gas. This eliminates the need for additional measures, which also contributes to improving the effectiveness of the gas turbine.

In addition, since the extension line of the blowout passage 8 is at an acute angle with respect to the tangent to the side surface of the blade, even if the pressure of the cooling air becomes greater than the pressure of the mainstream gas and blows out vigorously, A good film layer of cooling air is formed on the sides, so cooling performance and aerodynamic performance are not impaired.

In addition, since the stator vanes described above do not have holes for blowing out cooling air 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 different from the conventional blade structure. This can be simpler than a stator blade that blows air from the leading edge of the blade.

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 and has strength, and the aerodynamic force applied to the head 3 is also 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 wing head 3 and the wing body 2 form an interface with a convex shape on the wing body 2 side, even if the direction of the gas force acting on the wing head 3 changes, This force can be supported by the main body 2. 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. Further, even if the ceramic head is damaged for some reason, since the tip of the wing body 2 is convex, a certain level of aerodynamic performance can be maintained and it can be easily replaced.

As described above, the stationary blade of the gas turbine according to the present invention is configured such that the blade head for damming mainstream gas is separated from the blade body and is made of ceramic, and the boundary surface between the blade head and the blade body is formed with a convex surface on the blade body side. and
The extension line of the boundary surface is formed at an acute angle to the tangent to the side surface of the blade, and a cooling air blowing passage is provided along this boundary surface, and this blowing passage is blown into the hollow part of the blade body. The structure is such that the hollow part is connected to the cooling air supply source, which reduces the amount of cooling air, and 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. In addition, ceramic can withstand higher temperatures than metals, so it is possible to increase the temperature of the mainstream gas without increasing the amount of cooling air, and from this aspect it is possible to improve efficiency, due to the synergistic effect of increasing the temperature of the mainstream gas and reducing the amount of cooling air. Improvements in gas turbine efficiency can also be made.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a stationary blade of a gas turbine according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken in the direction of the − arrow in FIG. 1, and FIG. 3 is another embodiment example corresponding to FIG. 2. FIG. 4 is a longitudinal sectional view of a stationary blade according to another 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 is made of ceramic, and the boundary surface between the wing head and the wing body is a convex surface on the wing body side, and the extension line of the boundary surface forms an acute angle with the tangent to the wing side surface. At the same time, a cooling air blowing passage is provided along the boundary surface, and this blowing passage is communicated with a hollow part in the blade body through a blowing hole, and this hollow part is used as a cooling air supply source. A stationary blade of a gas turbine characterized by being connected to a stationary blade.