JPS5979006A - Air cooling blade of gas turbine - Google Patents

Abstract

PURPOSE:To make it possible to utilize as sealing air the air which has been used for cooling the turbine bucket by a method wherein a cooling air passage in the turbine bucket is made to open in an intermediate chamber between the rotor and the operating gas passage. CONSTITUTION:The outlet port 72 of the cooling air passage 71 in the bucket of the movable blade 7 is made to open in a shank chamber 37 formed within the shank of the blade 7 and a flowout hole 73 is provided underside a sealing fin 55 on the side wall 35 of the shank so as to open in the intermediate chamber 52. Thus, the cooling air passed through the cooling air passage 71 is flowed into the intermediate chamber 52 from the flowout hole 73 so that it is reused as sealing air for the prevention of the flowing out of the operating gas and as leak air for labyrinth sealing.

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. Therefore, efficient cooling of the moving blades, stator blades, rotors that rotatably support the moving blades, etc. on the turbine working gas passage, which is combustion gas, 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.

Below is an example of a conventional gas turbine cooling structure.
This will be explained with reference to FIG. The figure shows only the part where the rotor blades and stationary blades are incorporated, and shows a partial cross section. The rotor blade 2 usually consists of a dovetail 31 serving as an implant to the rotor, a shank 3, and a packet 21 protruding into the working gas passage 6, as shown in the figure. A complicated cooling channel 22 is configured inside the packet 21, and its outlet 23
is a recess 24 at the tip of the packet 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 is branched from the center of the rotor 1 at a diaphragm 32 formed at the doptail 31, and introduced through the shank 3, into the packet internal flow path 22, as shown by the arrow 33. ing. FIG. 2 shows the cross-sectional shape of the rotor blade cooling channel 22 shown in FIG. The column 34, the front and rear side walls 35, the platform 36, and the doptail 31 are removed to reduce weight, and by arranging the rotor blades in the circumferential direction, the strut 34, the front and rear side walls 35, the platform 36, and the doptail 31
A shank chamber 37 is formed surrounded by. 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 passage 41 similar to the rotor blade formed therein, and the stator blade also has a reed 142 in the center. 5 to the outflow hole 51 through the inside of the diaphragm 5.
A 7-hole air flow path 53 is provided which communicates with an intermediate chamber 52 surrounded and formed between the rotor 1 and the rotor 1. Seal air is supplied to the intermediate chamber 52 through this passage 53, and sealing fins 54 and 55 are provided to prevent high temperature gas from flowing out from the working gas passage 6 into the intermediate chamber 52 through the gap between the rotating body and the stationary body.
and supply a constant amount of air in the direction of the working gas passage, as well as a labyrinth.

The air leaking from the seal 56 is replenished. This leak air becomes seal air for preventing leakage of the working gas at the seal fin 57 on the downstream side and flows into the working gas passage 6.

In this way, there are many cooling channels configured inside the aircraft.
Since all of this cooling air is mixed into the working gas, the temperature of the turbine working gas decreases due to the mixing of low-temperature air, leading 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 sealing characteristics necessary to prevent the leakage of working gas, and simply ensuring the flow direction is insufficient, so a large flow rate is required, and leakage from the 2-birinsing seal is required. Together with air, it 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 is necessary.

[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 invention is to reuse the air used for cooling the packet as sealing air by opening the cooling passage within the packet into 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 flow path configuration changed without changing its external shape, and is Q that can be applied to the gas turbine shown in Figure 1. The turbine configuration diagram of the outside of the rotor blade has been omitted. . Next, in the present invention, the cooling channel 7 in the vJ blade 7
The output lower 2 of 1 is connected to the shank chamber 3 formed between the shanks.
In addition, the seal fin 55 of the shank side wall 35 is also configured to have an outflow hole 73 opened on the inner diameter side. With this configuration, the cooling air flows from the header 32 of the doptail part into the cooling channel 71 in the packet as shown by the arrow 74, reverses the flow direction at the tip, and flows into the shank chamber 37. It flows out from the outflow hole 73 into the intermediate chamber 52 formed between the rotor 1 and the diaphragm 5,
It is used as seal air to prevent the leakage of working gas and as leak air for two-birinse seals. That is, the present invention recovers the cooling air of the packet and uses it as sealing air, thereby saving most of the sealing air required in the past, and reducing the temperature drop in the turbine working gas due to mixing of the cooling air. Moreover, the outlet pressure of the cooling flow path is not affected by the working gas pressure, and each tlrf, w! The advantage is that the air flow source required for cooling the rotor blades can be easily and accurately controlled because the pressure can be set to a common constant pressure and this pressure can be adjusted by the flow path area of the outflow hole 73. There is. Furthermore, by setting the above-mentioned constant pressure to an appropriate value higher than the pressure of the mobilized population, the recovered air can be transferred to the platform 36.
By allowing a small amount of the gas to flow out into the working gas passage, the seal bottle 38 that was conventionally required can be omitted. The channel in the packet of the embodiment shows a case in which two channels are merged into one and returned, and one film cooling channel is added, but the present invention Exit 1
This does not limit the flow path configuration other than opening part or all of the part into the intermediate chamber, or the introduction path of the cooling air into the packet. It can also be applied to the case where it is led out to the intermediate chamber 52.

〔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 the air for cooling the rotor blades and utilizing it for arm effect.

[Brief explanation of drawings]

Fig. 1 is a partial view showing the rotor blade and stator blade rotation υ of a conventional gas turbine, Fig. 2 is a partial view of Fig. 1 taken from - and arrow, and Fig. 3 is an embodiment of the rotor blade according to the present invention. FIG. 3 is a partial cross-sectional view of an example. 7... aL37... Shank chamber, 38... Seal pin, 52... Intermediate chamber, s 4... Seal fin,
55... Seal fin, 56... Labyrinth seal, 71... Cooler 1I ¥1 122 20th

Claims (1)

[Claims] 1. In a gas turbine rotor blade having an air-cooled cooling passage inside the packet, the outlet of the cooling passage in the packet is connected to a wall forming the passage outside the turbine working gas passage and the rotor. A gas turbine air-cooled rotor blade configured to open into an intermediate chamber formed between the blades.