JPS58122302A - Method and device for introducing cooling air into gas turbine rotor - Google Patents

Abstract

PURPOSE:To reduce a flow loss which would be caused by the sharp expansion and contraction of a fluid passage, by providing a duct to conduct cooling air to the hollow central part of a turbine rotor. CONSTITUTION:A duct 10 for conducting cooling air 7 from the through hole 2 of the side wall of a stub shaft rotor 1 to its hollow central part 1' is secured with a support 13 on the rotor. Since the cooling air introduced from outside is conducted to the central part 1' of the rotor 1 through the fluid passage, turbulences are prevented from being caused by the sharp expansion and contraction of a cooling air passage. The flow loss is thus reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for introducing cooling air into a gas turbine rotor and an apparatus used therefor.

2. Description of the Related Art Conventionally, a technique shown in FIG. 1, for example, has been adopted as a technique for cooling the rotating parts of a gas turbine by introducing cooling air from the outside. In this conventional example, cooling air 7
The rotor is taken in through a through hole 2 provided in one axial side wall of the rotor, made hollow, and distributed to each stage through the round shaft center 1'. As shown in Figure 1, this includes:
In the basic structure, a plurality of rotor disks 3 and spacers 5, each having rotor blades 4 embedded in the outer periphery, are fastened together with tie bolts 6 between stub shaft ICs located at both axial ends of the turbine rotor. In order to form a cooling flow path to each stage, a plurality of through holes 2 are provided in the side wall of one stub shaft 1, and the axial center of each rotor disk 3 is hollowed out to form a through flow path in the axial direction. Furthermore, a design is made in which a radial flow path is provided between the rotardistor 3 and the svana 5. The cooling air 7 sequentially flows through the flow path, and after cooling the inside of the rotor blades 4 and sealing the gaps between rotating and stationary bodies, it is blown out into the gas flow path and mixed with the high-temperature gas 8. However, with this method, the flow loss in the first half of the introduction process increases as the rotation speed increases, and the pressure difference between each stage of the turbine fluctuates and is therefore difficult to design the distribution of cooling air flow to each stage. There are drawbacks.

This problem will be clarified using FIG.

That is, in the prior art, the fact that the flow loss increases with rotation can be understood by analyzing the state of the flow of cooling air at each position inside the rotor shown in FIG. In the figure, the streamlines seen from a viewpoint fixed to the rotor are shown by solid lines with arrows and broken lines, and at each position 11 to 11, the combined speeds in the axial and radial directions are shown by solid arrows. Further, circumferential velocities are indicated by spiral broken line arrows.

Figure 3 shows pressure distribution data during the introduction process in the model rotor. The horizontal axis shows the turbine O axial positions 1 to f (see FIG. 2) and t.

Apply pressure (ate) to the vertical axis. The pressure distribution during non-rotation is shown by a solid line, and the pressure distribution during one rotation (65OOri)m) is shown by a broken line. As you can see from this diagram.

(As shown in the pressure distribution data shown by the solid line when the rotor is not rotating) Although flow loss occurs due to sudden expansion and contraction of the flow path during one pass, the overall loss is small, but as the number of rotations increases, the loss increases. increases, and q# between positions 1 and 6 and d
The increase in flow loss between - and e becomes the original paper. This is shown by the broken line in FIG.

Regarding the occurrence of flow loss such as ζO, let us return to Figure 2 and examine the cause. First of all, in the location hot~b Sekio Kagamo,
The cooling air 7, which is at low speed and has almost no circumferential velocity, is introduced into the through hole 2, which has a large circumferential velocity difference due to the strength constraints of the rotor, through the through hole 2, which has a large circumferential velocity difference. It is strongly amplified and causes a larger loss than when it is not rotating. The inflowing cooling air 7 is at position b-+c→
d, the circumferential velocity increases, and the axial passage through the center of the rotor disk 3 has a circumferential velocity that is much larger than the inner circumferential surface. In such a situation, the flow near the inner circumferential surface of the rotor disk 3 tends to become unstable (rounded or curved), which promotes the growth of flow turbulence 9 that occurs when flowing in.

Here too, the loss increases during rotation.

As can be seen from the above explanation, this increase in flow loss is caused by the fact that the circumferential velocity component imparted to the cooling air 7 at the time of introduction promotes the generation of turbulence 9 in the flow path inside the rotor. ing. Therefore.

As a measure to reduce this, it is sufficient to reduce the applied circumferential velocity or to control the flow so that the turbulence is not amplified.

It is an object of the present invention to achieve the above-mentioned hollow rotor without changing the basic structure for introducing cooling air into the hollow rotor, by simply making improvements to the conventional rotor, and to provide cooling air even during rotation. It is an object of the present invention to provide an advantageous method and apparatus for introducing cooling air into a gas turbine rotor, which causes less flow loss during the introduction process.

In order to achieve this object, one aspect of the present invention is as follows.

When cooling air is introduced into the hollow rotor of a rotating gas turbine to cool the rotating part, a method is adopted in which the cooling air introduced from the outside is guided to the vicinity of the center of the rotor through a flow path.

With such a flow path, the flow can be controlled and turbulence can be prevented from being amplified, so that flow loss can be reduced.

To implement the method employing such a flow path, a device obtained by adding a simple structure to the rotor can be used.

That is, this cooling device can be introduced by providing a through hole in the rotor am and adding a structure to the rotor that constitutes a flow path that guides cooling air to the hollow center of the shaft inside the rotor through the through hole. The device can be configured.

An embodiment of the present invention will be described below using Figure #E4.

This system introduces cooling air 7 into the hollow rotor of a gas turbine during one revolution to cool the rotating part.A through hole 2 is provided in the side wall of the rotor, and a hollow shaft center part 1 inside the rotor is provided.
A duct 10 constituting a flow path for guiding cooling air 7 to the rotor is added to the rotor through a through hole 2.

This duct 10 is installed in addition to the rotor.

In this example, the population 11 opens at the position of the through hole 2 provided at the mid-radius position of the stub shaft 1 forming the outer wall of the rotor, and the outlet 12 opens at the center of the hollow shaft inside the rotor. . Any intermediate route may be selected to connect the two, and the duct 10 is fixed to the systub shaft 1 by a support member 13 or the like. If the cooling air 7 taken into the rotor is guided through such a duct 10.

Unlike in the past, there is no sudden expansion or contraction in the intermediate path, and since the flow is limited to the rotating tube, amplification of turbulence caused by circumferential velocity differences is suppressed, and the final flow is applied to the cooling air 7. The circumferential velocity also becomes small.

Therefore, flow loss in the first half of the cooling air introduction process can be suppressed. As a result, the pressure difference between each stage of the turbine also fluctuates, making it easier to design the distribution of the cooling air flow rate to each stage. This is because the pressure loss at both ends of the introduction process is reduced, so the inlet pressure when distributing cooling air to each stage does not deviate much from the set value. (The outlet pressure is fixed).

Also.

In the conventional technology, the cooling effect of the second stage (the one that receives the steam first) at the back, which requires cooling (the first stage), is smaller, but with a single stage, cooling can be done almost uniformly and the cooling efficiency is good.

In this example device, since the inlet 11 of the duct is located on the outer periphery of the outlet 12, there is a problem in that the centrifugal force acting on the cooling air 7 in the duct pushes back the flow as a whole.

However, this is also small within the normal shape and size range. For example, in the case of the model rotor shown in Fig. 3, the effect of pushing back the flow due to centrifugal force is approximately 0.15 ata in pressure difference;
With the addition of the duct, the conventional total loss of 2ata due to the introduction to the center of the shaft is reduced to half or less, so the overall loss is reduced even after subtracting the effect of the former.

Further, in this embodiment, a partition plate or a grid may be provided in order to enhance the rectification effect within the duct 10.

This is shown schematically in FIG. Same figure (a)
(b) Each lattice 101. Horizontal partitions 102 are provided, and (c) shows a grid 101.7't in each duct lO with a rectangular cross section and partitions 103.
However, it goes without saying that various other forms can be adopted. This rectifying action controls the flow, and in particular eliminates the swirling component at the inlet 11, so that the pressure loss caused by such vortex generation is effectively eliminated.

Furthermore, as shown in FIG. 6, a plurality of ducts 104 may be joined in the middle.

As described above, in this embodiment, the cooling air taken into the a-tube is cooled by flowing through the duct.

Since large turbulence does not occur, flow loss during the introduction process can be reduced.

As a modification of the above embodiment, there is a configuration example in which the duct is extended to the outside of the rotor, and the inlet of the duct is shaped to facilitate the intake of cooling air. FIG. 7 shows an example of this. Since the inlet 11 of the duct 10 is open toward the inner circumference of the outside of the rotor, the difference in speed in the circumferential direction with the cooling air 7 to be taken in is small, making it possible to take in the air effectively. is possible. As another example, the direction of the inlet of the duct may be made to directly face the cooling air in the circumferential direction, so that the pushing action is caused by the circumferential speed difference.

For example, as schematically illustrated in FIG. 8, the duct 10 is bent circumferentially so that its opening 11 faces the circumferential air flow. In this example, cooling air is effectively taken in at the duct inlet. Moreover, since the same effect as in the example of Mayuki can be expected for the duct inside the rotor, the flow loss during the introduction process will be reduced.

Although ducts are used as the structures constituting the flow passages on each side, it goes without saying that ducts having a structure that functions like a ground circuit may also be used.

As mentioned above, the technology for introducing cooling air into the gas turbine rotor of the present invention is such that the cooling air introduced from the outside is guided near the center of the rotor through a flow path, so there is no need to change the conventional basic structure. Therefore, it can be obtained by simply making improvements to the conventional one. In addition, during rotation, there is less flow loss during the cooling air introduction process, which is advantageous in terms of cooling effect. Furthermore, since the flow loss is small, the design of cooling air amount distribution to each stage of the turbine is also facilitated.

It should be noted that the present invention is not limited to the nine illustrated embodiments.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view of a conventional example. FIG. 2 is a partially enlarged sectional view showing the flow state during the cooling air introduction process on the line side. FIG. 3 is a graph showing pressure changes during the introduction process. FIG. 4 is a partial sectional view showing one embodiment of the present invention. FIG. 5 is a fifth partially sectional view. 1... Rotor (stub shaft), 2... Through hole &
3... Rotor (rotor disk), 7... Cooling air. 10... Structure (duct) (constituting a flow path). 11... Inlet of structure (duct), 12... Outlet of structure (duct). Agent Patent Attorney Masami Akimoto No. 2I2] Figure 3 Figure 40 “is [] (4) (B) (Han (D)) Figure 6

Claims (1)

[Claims] 1. In a method of introducing cooling air into a rotating hollow rotor of a rotating gas turbine to cool the rotating part thereof, cooling air introduced from the outside is guided to the vicinity of the center of the rotor through a flow path. A method for introducing cooling air into a gas turbine router, characterized in that: 2. In a gas turbine cooling air introduction device configured to introduce cooling air into the hollow rotor of a rotating gas turbine to cool the rotating portion thereof, a through hole is provided in the side wall of the rotor, and a hollow shaft center portion inside the rotor is provided with a through hole in the side wall of the rotor. 9. A device for introducing cooling air into a gas turbine rotor, characterized in that the structure is added to the rotor through a cough through hole, and a structure constituting a flow path for guiding cooling air to the rotor. 1. The cooling air introduction device to a gas turbine rotor according to claim 2, wherein the cooling air inlet of the structure is located at a location where the through hole is located. The cooling air introduction device to the gas turbine rotor according to claim 2, wherein the cooling air inlet of the structure is located outside the through hole.