JPS6036725Y2 - gas turbine engine shroud - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a shroud that covers the radially outer side of a turbine in a gas turbine engine.

(Prior Art) This type of shroud faces problems such as cracking and deformation due to large thermal stress because its inner surface is constantly exposed to high-temperature gas, while its outer surface is exposed to low-temperature outside air or compressor air.

If an attempt is made to increase the turbine inlet temperature in order to improve the thermal efficiency of the gas turbine engine, the above problem becomes more severe.

Additionally, reducing the clearance between the tip (outer end) of the turbine blade and the inner surface of the shroud improves turbine performance, but if the shroud is deformed significantly, the inner surface of the shroud expands locally in the radial direction. The problem is that the clearance has to be increased even at the cost of sacrificing the performance of the turbine because the blade is distorted in the circumferential direction and comes into contact with the tip of the turbine.

(Purpose of the invention) This invention was made in view of the above-mentioned problems. It prevents shroud cracking and deformation, improves turbine performance, and provides a gas turbine engine shroud with a simple structure and high strength. The purpose is to provide.

(Structure of the invention) In order to distantly relate to the above object, this invention provides a slit that penetrates the inner surface of the shroud in the axial direction and extends in the radial direction; In addition, a hole with a circular cross section communicating with the radially outer end of the slit is provided, and a sealing member is fitted into this hole in a substantially tight state, thereby preventing the slit from generating large thermal stress in the shroud. At the same time, the hole and seal member simplify the structure and prevent leakage of high temperature gas.

Example Embodiments of this invention will be described below with reference to the drawings.

In FIG. 1, a first-stage nozzle 11, a turbine 13 fixed to a rotating shaft 12, and a cylindrical shroud that is brazed A to the first-stage nozzle 11 and covers the outside of the turbine 13 in the radial direction. 14 and the second-stage nozzle 15 form an annular passage 17 for high-temperature gas 16, and the high-temperature gas 16 sent from the combustor (not shown) passes through the first-stage nozzle 11. After passing through the stator blades 18 of the turbine 13, energy is released by the rotor blades 19 of the turbine 13 to rotate the turbine 13, and the energy is passed through the stator blades 20 of the second stage nozzle 15 and discharged to the outside. Ru.

As clearly shown in FIG. 2, in the inner surface 21 of the shroud 14 that comes into contact with the high temperature gas 16, there is a slit 22 that penetrates in the axial direction and extends in the radial direction 31.
A large number of slits 22 are provided at equal intervals, and the outer end of each slit 22 communicates with a hole 23 for preventing cracking.

As clearly shown in FIG. 1, a pin 24, which is a sealing member, is fitted into the hole 23 in a substantially tight state.
This prevents the high temperature gas 16 from passing through the hole 23 and being exposed to the outside.

The width a and the circumferential spacing of the slits 22 may be determined as appropriate depending on the performance and temperature conditions of the turbine. If the temperature of the inner surface 21 of the shroud 14 becomes extremely high, the spacing may be reduced to reduce the performance of the turbine. If you want to avoid this as much as possible, it is better to reduce the width a.

In the above configuration, the outer surface 25 of the shroud 14 is exposed to outside air and cooling air from a compressor (not shown) and becomes low temperature, whereas the inner surface 21 of the shroud 14 is exposed to high temperature gas 16 and becomes high temperature. A large temperature gradient occurs in the shroud 14 in the radial direction 31.

Further, since the temperature of the high temperature gas 16 decreases as it goes downstream, a temperature gradient also occurs in the shroud 14 in the axial direction 33.

However, since the inner surface 21 is provided with a slit 22 that penetrates in the axial direction and extends in the radial direction 31,
Since this inner surface 21 is not constrained in the circumferential direction 32 and axial direction 33, generation of large thermal stress due to temperature gradients in the radial direction 31 and axial direction 33 is avoided, and as a result,
Problems such as cracking and deformation are prevented from occurring.

In particular, as a result of preventing the inner surface 21 of the shroud 14 from expanding locally inward in the radial direction, the clearance d (see FIG. 2) between the inner surface 21 and the tip (outer end) 27 of the turbine 13 is reduced in advance. By setting it small, it is possible to improve the performance of the turbine.

Furthermore, when a single counterflow can-shaped combustor protruding in the radial direction 31 is used as a combustor, the high temperature gas 16 has an uneven temperature distribution in the circumferential direction 32 in the passage 17, so that the shroud 14 also has a non-uniform temperature distribution in the circumferential direction 32. Although a temperature gradient occurs in the direction 32, the presence of the slit 22 prevents generation of large thermal stress due to this temperature gradient in the circumferential direction 32.

Further, since the pin 24 is fitted in the hole 23 provided in the shroud 14 in a substantially tight state, the high temperature gas 16 is prevented from leaking through the hole 23 in the radial and axial directions.

However, although it is unavoidable that some high-temperature gas 16 leaks in the axial direction through the slit 22,
Since the width of the slit 22 can be made small, the leakage through the slit 22 is suppressed as much as possible, so there is no problem in practical use.

Moreover, the shroud 14 can be formed in one piece as in the conventional case, and since the hole 23 has a circular cross section, the shroud 14 itself can be manufactured easily by machining.

Further, a hole 2 having a circular cross section is provided at the outer end of the slit 22.
3, the occurrence of cracks due to stress concentration is effectively prevented, and as a result, combined with the fact that the shroud 14 described above can be formed into an integral structure, the strength of the shroud 14 can be maintained at a high level.

Here, the configuration in which the hole 23 having a circular cross section is provided is as follows.
It is also extremely significant in the following points.

That is, in order to reduce the leakage of high-temperature gas, the width of the slit 22 needs to be small, and on the other hand, in order to suppress the thermal stress generated in the shroud 14, the radial depth of the slit 22 should be increased to some extent. There is a need to.

However, it is difficult to form a narrow and deep slit.

However, in this invention, since the hole 23 is provided, the slit 22 can be made shallower by the hole 23, so that the slit 22 can be formed easily.

Therefore, there is an advantage that the shroud 14 can be manufactured more easily.

(Effects of the invention) As explained above, 1. this invention has a slit provided on the inner surface of the shroud, which allows the radial direction 31 and the axial direction 33
Alternatively, generation of large thermal stress due to temperature gradient in the circumferential direction 32 can be avoided.

Further, by setting the clearance d between the inner surface of the shroud and the tip of the turbine small in advance, it is possible to improve the performance of the turbine.

In addition, the holes prevent stress concentration on the slits, and the pins (seal members) 24 prevent hot gas from leaking in the axial and radial directions.

In addition, since the shroud of integral structure is simply provided with a slit and a hole having a circular cross section, the structure is simple and manufacturing is easy.

Furthermore, the presence of the holes effectively prevents the occurrence of cracks due to stress concentration. This, in combination with the fact that the shroud can be formed as an integral structure, makes it possible to maintain high strength of the shroud.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view of a main part of a gas turbine engine showing an embodiment of this invention, and FIG. 2 is a front view showing a part of the shroud shown in FIG. 1. 13... Turbine, 14... Shroud, 16... High temperature gas, 17... Passage, 21... Inner surface, 22... ···slit,
24... Seal member (pin), 31...
・Radial direction.

Claims (1)

[Scope of utility model registration request] A slit that penetrates in the axial direction and extends in the radial direction is provided on the inner surface of the cylindrical shroud that covers the radially outer side of the turbine and forms a passage for the high-temperature gas that contacts the high-temperature gas, and the shroud has a slit that extends in the radial direction. penetrates in the axial direction,
A shroud for a gas turbine engine, characterized in that a hole having a circular cross section communicating with the radially outer end of the slit is provided, and a sealing member is fitted into the hole in a substantially tight state.