JPS59176401A - Air-cooled gas turbine - Google Patents

Abstract

PURPOSE:To reduce flow of cooling air by placing cooling passages of the first and the second stage moving blades in communication with each other and supplying the cooling air, after its cooling the first stage moving blade, as the cooling air for the second stage moving blade. CONSTITUTION:Both ends of a guide ring 72, formed outside a spacer 71 which forms a rotor 70, are fitted to side walls of the first and the second stage moving blades 80, 95 so that cooling passages of said blades 80, 95 are put in communication with each other via a space 73. After flowing into the rotor 70, the cooling air flows along an arrow 75 into the first stage moving blade 80 to cool it, and subsequently the air flows into the second stage moving blade 95 from a notch part 93 via the space 73. Thus, the cooling air is effectively utilized and its flow can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a cooling structure for moving blades and a rotor that constitute a power generating section of a gas turbine.

[Prior art]

In a gas turbine cycle, thermal efficiency can be improved by increasing the turbine inlet temperature and increasing the heat drop. For this reason, in a typical gas turbine, a portion of the compressed air for combustion is extracted as a refrigerant and a blade or the like is used as a cooler to raise the temperature of the working gas. Therefore, in order to maximize the overall efficiency of the entire turbine, it is necessary to reduce the amount of extracted air as much as possible for effective cooling.

This type of gas turbine will be explained below using figures.

FIG. 1 shows a cross-sectional structure of a rotor blade and a rotor portion of a conventional gas turbine. 10 is a rotor, and 20 and 30 are a first stage rotor blade and a second stage rotor blade, respectively. In the same figure, the working gas flows in the direction shown by the arrow 60, and the working gas flows between the stator vanes 40, 50 and the movable blade 420.
．． By passing through 30 alternately and repeating the expansion,
Power is generated as the rotational force of the rotor 10. The temperature of the combustion gas, which is the working gas, far exceeds the heat resistance temperature of the blade material in order to improve turbine efficiency. It has a structure in which complicated cooling channels 21 and 31 are provided inside it, and air as a refrigerant is directly connected to the rotor 10, and combustion air is generated by a compressor that is driven by a part of the generated power. A portion of the air is extracted and introduced along arrow 61 through an external heat exchanger, or alternatively, it is guided directly from the compressor through the center of rotor 10 along arrow 62 for cooling. There is. Since the temperature of the working gas decreases as it goes to the later stages, the cooling heat load on the rotor blades differs for each stage, and the high-pressure stage side has a complex cooling structure, which also varies depending on the temperature level of the working gas. Cooling is enhanced by the turbulent promoter 22, bin fins 23, etc. that promote heat transfer, and the flow rate of cooling air is also distributed using the cooling flow path resistance according to the heat load. The air used for these cooling is
4, or flows out from the outlet of the flow path 31 at the tip of the Wb blade 30 and mixes into the working gas. Therefore, extracting the cooling air requires extra power for the compressor, mixes it into the working gas and lowers its temperature, and also absorbs rotational energy into the cooling air as it passes through the rotor 10. This is a major factor in reducing the efficiency of the gas turbine, and even though efficiency has been improved by increasing the temperature of the working gas, the effect cannot be exerted on light components.

[Purpose of the invention]

An object of the present invention is to provide a highly efficient gas turbine by effectively utilizing cooling air and reducing its flow rate.

[Summary of the invention]

The present invention focuses on the fact that by expanding the heat transfer area inside the second-stage rotor blade, the second-stage rotor blade can be cooled under the exhaust air conditions after cooling the first-stage rotor blade. The outlet of the cooling channel in the blade communicates with the inlet of the cooling channel in the second stage rotor blade via the rotor, so that the exhaust air of the first stage rotor blade cools the second stage rotor blade. .

[Embodiments of the invention]

Hereinafter, the rotor blade and cooling passage configuration in the quadrature according to the present invention will be explained with reference to FIG. As for the first stage rotor blade, as shown in FIGS. 3 and 4, the flow path in the center is partitioned by dividing the
1 and a flow path 82 on the outer periphery. The flow path 82 on the outer periphery is further provided with a lip 84 for reinforcing the rotor blade against external forces and distributing the flow rate of cooling air according to the thermal load on the outer surface of the blade.
It is partitioned into multiple flow channels. The center flow path 81 and the outer peripheral flow path 82 communicate with each other through a communication hole 86 at the tip of the blade or a plurality of blow holes 87 drilled in the radial direction of the blade at the leading and trailing edges where the heat load is large. The other end of the channel 82 further opens into the side of the shank 90 in a portion near the platform 89 of the wing, as shown in FIG. This opening is surrounded by the partition 92 and platform 89 and conventional shank sidewalls, and the adjoining wings allow the header 9
2 and is open to the outside of the wing through a notch 93 in the side wall of the shank. On the other hand, the second stage rotor blade 95 has an inlet 9 located near the platform on the high pressure side wall of the shank.
6, it branches into a plurality of cooling channels 97 through the inside of the shank, and opens into a working gas channel at the tip of the blade. This cooling flow path 97 has a larger hole diameter than the conventional cooling flow path to enlarge the heat transfer surface and the cross-sectional area of the flow path. Furthermore, a guide ring 72 is formed integrally with the spacer 71 on the outside of the spacer 71 forming the rotor 70, and both ends of the guide ring 72 are fitted near the platforms of the side walls of the first and second stage rotor blades. The cooling channels of the first-stage rotor blade and the second-stage rotor blade are communicated through a space 73 between the rotor blade and the guide link. Therefore, the cooling air that has flowed into the rotor 70 from the cooling air inflow holes 76 that have sprouted in the disk flows into the first stage rotor blades at the outer circumference of the disk along the arrow 75, and flows through the center flow passage 81 and the communication hole 86. After cooling the rotor blade by circulating inside the rotor blade in this order through the blow-off hole 85, the outer circumferential flow path 82, and the header 91, it flows out from the notch 93 into the space 73 of the blade portion, and passes through the space into the guide ring 72. The gas flows into the second-stage rotor blade through the inlet 96 under guidance, is cooled, and is then discharged from the blade tip into the working gas flow path. The flow path passing through the hole 77 penetrating the spacer 71 is a dovetail 9 that engages the second stage rotor blade and the disk.
8, which rotatably supports the rotor blades and generates the greatest stress, so it is cooled by the cooling air immediately after the rotor drifts, and then it is cooled by the cooling air immediately after the rotor drifts, and then in the first stage rotor blade exhaust air in the space 73. Mixed.

The first stage rotor blade differs in that the conventional structure in which air is blown out from the trailing edge has been changed to a recovery type, but the basic cooling method is almost the same, and the inflow conditions for cooling air are also exactly the same. Therefore, the same cooling effect as before can be obtained. Since the second stage rotor blades use the exhaust air for cooling the first stage rotor blades, the temperature level of the cooling air increases, but the cross-sectional area of the convection cooling channel increases proportionally to the change in flow rate. As a result, the convective heat transfer coefficient increases in proportion to the 0.4th power of the flow rate increase ratio, making it possible to supply a flow rate that is more than twice the conventional two-stage rotor blade cooling air flow rate. As a result, the cooling efficiency of the entire blade is greatly improved, and the conventional blade temperature level can be maintained. On the other hand, the air flow rate required to cool the dovetail is not directly exposed to the turbine working gas, and since the shank is long in the radial direction, there is a large resistance to heat flow from the high temperature blade section to the dovetail. Since the heat load is very small,
A small amount is sufficient. therefore,? It is possible to reduce the flow rate close to the two-stage rotor blade cooling air flow rate required in the past. !
! In addition, since the flow rate of cooling air is large, there is a small temperature change during cooling of the air, which has the advantage of reducing unevenness in the temperature distribution of the blade surface. Furthermore, when compressed air is supplied to the rotor after passing through an external heat exchanger, the saved cooling air flow rate can be added and supplied to the first stage rotor blades. Since the cooling efficiency is improved and the temperature of the exhaust air is lowered, the cooling effect of the second stage rotor blades is also improved, and if the cooling air flow rate is kept the same as before, the turbine inlet temperature can be raised. On the other hand, in terms of turbine efficiency, the power generated by the second stage rotor blades is reduced by the amount of cooling air no longer discharged by the first stage rotor blades, but this exhaust air does not mix into the working gas. It is more effective to prevent the temperature of the working gas from decreasing due to cooling air, and the power of the compressor and the power of rotating the cooling air at the same time as the rotor, which are offset by the savings in cooling air, are reduced, and the overall turbine Efficiency can be improved.

FIG. 5 shows a longitudinal section of a first stage rotor blade 100 showing another embodiment of the present invention, and the difference from the rotor blades shown in FIGS. 2 to 4 is that cooling air is The outer circumferential flow path 8
2 first, merges into the center channel 81, and collects it, and eliminates the partition 92 in FIG. 4 and discharges from the hole i02 to the wing section. This is exactly the same as the previous embodiment. According to this embodiment, the third
Although the effect of impingement cooling by the blow-off holes 85 shown in the figure is lost, there is an advantage that the structure is simplified by eliminating the partition 92.

In the figure, 11 is an inflow hole, 80 is a first stage rotor blade, 88 is a pin fin, 90 is a shank, and 92 is a partition.

In the embodiments of the first stage rotor blades shown in Figures 2 to 5, all of the cooling air is recovered, but it is possible to partially provide blow-off holes on the blade surface to strengthen cooling. Also within the scope of this invention.

〔Effect of the invention〕

According to the present invention, since cooling efficiency can be improved with a small flow rate of cooling air, a highly efficient gas turbine can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a conventional gas turbine, and FIG. 2 is a partial sectional view of a gas turbine configured with a cooling flow path according to the present invention.
3 is a cross-sectional view taken along the line ■--■ in FIG. 2, FIG. 4 is a cross-sectional view taken along the line ■--■ in FIG. 2, and FIG. 5 is a partial cross-sectional view of another embodiment of the present invention. 72... Guide ring, 80.100... First stage rotor blade, 81.82. ．． 97... Cooling channel, 93... Outflow hole, 95... Second stage rotor blade, 96... Inflow hole. Figure 1: ? Figure 2 Figure 3 n Ring 4 Figure 2

Claims (1)

[Claims] 1. The rotor blades are made up of multiple stages. 9. Cooling channels are provided inside the first and second stage rotor blades, and a portion of the compressed air for combustion is supplied to the cooling channels. In an air-cooled gas turbine, the cooling flow paths of the first stage and second stage rotor blades are connected in series so that all or part of the air supplied for cooling the first stage rotor blades is An air-cooled gas turbine characterized in that the air is recovered and the recovered air is supplied for cooling the second stage rotor blades. 2. The front E cooling channel formed in the blade of the first stage rotor blade has a double structure, and the inner and outer channels are connected at the tip or middle part of the blade, while the other end is dovetailed. The other one is opened on the side of the shank on the side of the second stage rotor blade, and the inlet of the cooling flow path in the second stage rotor blade is connected to the first stage rotor blade*U. A guide link is provided on the outer periphery of a spacer that opens on the side surface of the shank of the rotor blades and is located between the disks that support the rotor blades, and the space formed between the guide ring and the spacer connects the shanks of both rotor blades. 2. The air-cooled gas turbine according to claim 1, wherein the side openings of the air-cooled gas turbine are configured to communicate with each other.