JPS6364601B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to gas turbines, and more particularly to air-cooled gas turbine rotor blades.

[Prior art]

The thermal efficiency of a gas turbine is significantly improved by increasing the turbine inlet temperature. For this reason, the rotor blades on the turbine working gas passage, which is combustion gas,
Efficiently cooling the stator blades and the rotor that rotatably supports the rotor blades is effective in improving the efficiency of the turbine. This cooling efficiency is greatly influenced by the cooling structure of each part and the flow rate of the refrigerant. Generally, a gas turbine is cooled by extracting a portion of the combustion compressed air generated by a compressor directly connected to the turbine. Therefore, from the viewpoint of the overall efficiency of the turbine, it is desirable to effectively cool the turbine with as little flow rate as possible.

An example of a conventional cooling structure for a gas turbine will be described below with reference to FIG. The figure shows only the part where the moving blades and stationary blades are incorporated, and is partially shown in cross section. As shown in the figure, the rotor blade 2 usually consists of a dovetail 31 serving as a part to be attached to the rotor, a shank 3, and a bucket 21 protruding into the working gas passage 6. A complicated cooling channel 22 is configured inside the bucket 21, and an outlet 23 thereof is configured.
This is a recess 24 at the tip of the bucket or a blowout hole 25 for cooling the film, which is opened on the outer surface of the blade and directly communicates with the working gas passage. In the illustrated example, the cooling air flows from the center of the rotor 1 to the header 3 formed in the dovetail 31 portion of the bucket internal flow path 22, as shown by the arrow 33.
It is branched at 2 and introduced through shank 3. FIG. 2 shows the cross-sectional shape of the rotor blade cooling channel 22 shown in FIG. 1 and the rotor blades in contact with both sides.
A directional view is shown. As shown, the center part of shank 3 has been removed to reduce weight.
By arranging the rotor blades in the circumferential direction, a shank chamber 37 surrounded by a strut 34, front and rear side walls 35, a platform 36, and a dovetail 31 is formed between adjacent shanks. A seal pin 38 is provided on the mating surface of the platform 36 with the adjacent one to prevent hot gas from entering the shank chamber 37 from the outer working gas passage 6. On the other hand, the stator blade 4 also has a cooling flow path 41 similar to the rotor blade formed therein, and the stator blade also has a pipe 42 provided in the center, and the diaphragm 5 is connected to the stator blade 4 from this pipe 42. A sealing air passage 53 is provided which reaches the outflow hole 51 through the inside and communicates with an intermediate chamber 52 surrounded and formed between the diaphragm 5 and the rotor 1. Seal air is supplied to the intermediate chamber 52 through this passage 53, and seal fins 54 and 55 are provided to prevent high temperature gas from flowing out into the intermediate chamber 52 from the working gas passage 6 through the gap between the rotating body and the stationary body, and , supplies a constant amount of air in the direction of the working gas passage, and replenishes leakage air from the labyrinth seal 56. This leak air flows into the working gas passage 6 as seal air for preventing leakage of the working gas at the seal fin 57 on the downstream side.

In this way, many cooling channels are configured inside the machine, and all of these cooling air is mixed into the working gas, so the temperature of the turbine working gas decreases due to the mixing of low-temperature air. This leads to a decrease in thermal efficiency. Furthermore, since blown film cooling disturbs the flow of working gas on the blade surface and similarly affects turbine efficiency, it is desirable to have a cooling structure that avoids it as much as possible. Furthermore, the sealing air flow rate of the fin seal has the sealing characteristics necessary to prevent the leakage of working gas, and the amount that simply ensures the flow direction is insufficient, and a considerable flow rate is required, and combined with the leakage air from the labyrinth seal. This is mostly wasted air that is not used for cooling. In order to further increase the temperature of gas turbines in the future, a cooling system that reduces wasteful air as much as possible and saves money is required.

[Purpose of the invention]

An object of the present invention is to provide a gas turbine air-cooled blade suitable for high temperatures.

[Summary of the invention]

The gist of the present invention is to reuse the air used for cooling the bucket as sealing air by opening the cooling passage in the bucket to an intermediate chamber between the rotor and the turbine working gas passage.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIG. The illustrated rotor blade has only the internal cooling passage configuration changed without changing its outer shape, and can be applied to the gas turbine shown in FIG. 1, so the turbine configuration diagram of the portion outside the rotor blade is omitted. That is, in the present invention, the outlet 72 of the cooling channel 71 in the rotor blade 7
is opened into the shank chamber 37 formed between the shank, and an outflow hole 73 is opened on the inner diameter side of the seal fin 55 of the shank side wall 35. With this configuration, cooling air flows from the header 32 in the dovetail portion into the cooling flow path 71 in the bucket as shown by the arrow 74, reverses the flow direction at the tip, flows into the shank chamber 37, and then flows through the outflow hole. 73 to rotor 1 and diaphragm 5
The air flows out into an intermediate chamber 52 formed between the two, and is used as seal air for preventing the working gas from flowing out and as leak air for the labyrinth seal. That is, the present invention can save most of the conventionally required sealing air by collecting the cooling air from the bucket and reusing it as sealing air, thereby reducing the temperature drop in the turbine working gas due to mixing of the cooling air. Further, the outlet pressure of the cooling flow path is not affected by the working gas pressure and can be kept at a common constant pressure for each flow path, and this pressure can be adjusted by the flow path area of the outflow hole 73. Therefore, there is an advantage that the air flow rate required for cooling the rotor blades can be easily and precisely controlled. Furthermore, by setting the above-mentioned constant pressure value to an appropriate value higher than the pressure at the rotor blade inlet, the recovered air is allowed to flow slightly from the platform 36 into the working gas passage, thereby reducing the seal pin 38 that was previously required. can be omitted. In the bucket internal flow path of the example, two flow paths are merged into one and returned, and
Although a configuration is shown in which one film cooling channel is added, the present invention is also applicable to a channel configuration other than opening a part or all of the channel outlet into the intermediate chamber, and a structure in which cooling air is introduced into the bucket. This does not restrict the introduction path, etc., and it can also be applied to the case where, for example, the support 37 is used to lead out to the intermediate chamber 52 without passing through the shank chamber 37.

〔Effect of the invention〕

According to the present invention, a highly efficient gas turbine can be obtained with a small flow rate of cooling air by recovering and effectively utilizing air for cooling rotor blades.

[Brief explanation of drawings]

Fig. 1 is a partial view showing the rotor blades and stationary blades of a conventional gas turbine, Fig. 2 is a cross-sectional view taken along the - arrow in Fig. 1, and Fig. 3 is a partial cross-section of one embodiment of the rotor blade according to the present invention. It is a diagram. 7... Moving blade, 37... Shank chamber, 38... Seal pin, 52... Intermediate chamber, 54... Seal fin, 55... Seal fin, 56... Labyrinth seal, 71... Cooling channel, 72... Outlet , 73
...Outflow hole.

Claims (1)

[Claims] 1. Sending seal air to the intermediate chamber 52 surrounded by the rotor blades 2, diaphragm 5, and rotor 1 to prevent working gas from entering the intermediate chamber from between the seal fins 55 and 54 provided on the rotor blades and the diaphragm. In the gas turbine rotor blade, a cooling flow path 71 is formed in the rotor blade to feed cooling air from the center of the rotor, and a part of the cooling air whose temperature has increased by flowing through this flow path is transferred to the rotor blade. A gas turbine air-cooled blade characterized in that it is provided with outlet ports 72 and 73 that lead into an intermediate chamber.