JPS5930190Y2 - Gas turbine engine air bearing cooling structure - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a cooling structure for an air bearing of a centrifugal gas turbine engine (hereinafter simply referred to as a gas turbine) in which the rear part of a turbine main shaft is supported by an air bearing.

Dynamic pressure type air bearings (hereinafter simply referred to as air bearings) used in gas turbines and the like maintain their durability by controlling the ambient temperature so as not to increase excessively.

In order to prevent the ambient temperature from rising excessively, low-temperature, high-pressure air from the gas turbine compressor is normally introduced into the air bearing chamber.

As a result, a large amount of air leaks from the back side of the radial turbine to the radial turbine side, causing damage to the radial turbine itself.
Furthermore, the performance of the gas turbine is reduced.

Furthermore, a large amount of low-temperature air flows into the combustion chamber, which causes a decrease in combustion efficiency.

The object of this invention is to provide a cooling structure for air bearings that does not have the above-mentioned drawbacks and has a simple structure.

This invention will be explained below with reference to drawings showing embodiments.

In the figure, 1 is a turbine main shaft, and a centrifugal compressor 2 is attached to the front part of the turbine main shaft.

At the rear end of the turbine main shaft 1 is a radial turbine 1 which will be described later.
4 is installed, and the centrifugal compressor 2 is connected to the radial turbine 1.
4 through the turbine main shaft 1.

19 and 20 are an outer casing and an inner casing of the gas turbine, respectively, and an annular low-temperature and high-pressure air passage 3 communicating with the outlet of the centrifugal compressor 2 is provided between the two casings.

A diffuser 21 is provided in the low temperature high pressure air passage 3 near the outlet of the centrifugal compressor 2.

An annular combustion chamber 11 surrounded by an inner wall 11a1 and an outer wall 11b is provided in the inner casing 20.
A large number of air holes 22 are provided in each of the outer walls 11a and l1bVC.

The combustion chamber 11 communicates with an annular combustion gas passage 23 , and a space between the combustion chamber 11 and the combustion gas passage 23 and the inner casing 20 forms a high-temperature, high-pressure air passage 24 .

The high temperature and high pressure air passage 24 communicates with the low temperature and high pressure air passage 3 via a heat exchanger (not shown).

A curved disk-shaped partition wall 7 is attached to the inner casing 20, extending behind the inner wall 11a of the combustion chamber 11 and consisting of an inner wall 7a and an outer wall 7b facing each other with a gap 10 in between.

The space behind the inner wall 11a of the combustion chamber 11 is divided by the partition wall 1 into a high-temperature, high-pressure air chamber 17 and an air bearing chamber 5, which are adjacent to the inner wall 11aK.

The inner wall 1a of the partition wall 1 is located on the side of the air bearing chamber 5, and a large number of ventilation holes 8 are provided in the largest radius part thereof, so that the gap 10 of the partition wall 1 and the air bearing chamber 5 are communicated with each other.

The gap 10 communicates with a high-temperature, high-pressure air chamber 11 through an outlet 9 at the minimum radius position of the partition wall 7 .

The combustion gas passage 23 has a plurality of cylindrical air inlets 25.
A pipe-shaped air passage 4 passing through the air inlet 25 and communicating between the low temperature and high pressure air passage 3 and the air bearing chamber 5 is supported by the inner casing 20 and the partition wall 7.

An air bearing 6 is disposed in the inner casing 20 in the air bearing chamber 5.
attached to a part of.

A turbine nozzle 13 communicates with the combustion gas passage 23.

Turbine nozzle 13 communicates with radial turbine 14 .

15 is a ring labyrinth provided between the air bearing 6 and the radial turbine 14; 16 is the inner casing 2;
This is a labyrinth seal installed between a part of the turbine shaft 1 and the turbine main shaft 1.

The turbine main shaft IK has a fuel injection port 1 communicating with the combustion chamber 11.
2 is provided.

A small-diameter fuel passage 1a is provided at the axial center of the turbine main shaft 1, and a fuel supply chamber 1b is connected to the rear end thereof.

In the above configuration, the low-temperature pressurized air that exits the centrifugal compressor 2 is decelerated and pressurized by the diffuser 21 to become low-temperature and high-pressure air, passes through the low-temperature and high-pressure air passage 3, and is heated by a heat exchanger (not shown) to produce high-temperature and high-pressure air. The air flows from the high-temperature, high-pressure passage 24 and the high-temperature, high-pressure air chamber 17 to the outer wall 11 of the combustion chamber 11.
b. It enters the combustion chamber 11 through the vent hole 22 in the inner wall 11a.

On the other hand, fuel is supplied to the combustion chamber 11 from the fuel jet port 12 through the fuel passage 1as and the fuel supply chamber 1b of the turbine main shaft 1, mixes with air, and is ignited by a spark plug (not shown) to be combusted.

The combustion gas passes through the combustion gas passage 23 to the turbine nozzle 13.
It expands through the radial turbine 14, passes through a heat exchanger at high temperature and low pressure, and is discharged into the atmosphere at low temperature and low pressure.

On the other hand, a part of the low-temperature high-pressure air in the low-temperature high-pressure air passage 3 flows into the air bearing chamber 5 through the air passage 4, cools the air bearing 6, and flows into the gap 10 through the ventilation hole 8 of the inner wall 7a of the partition wall 7. The high temperature and high pressure air chamber 1 flows from the outlet 9 through the gap 10.
1 and further flows into the combustion chamber 11 through the ventilation hole 22.

(The pressure is higher in the air bearing chamber 5 than in the high-temperature, high-pressure air chamber 17.) The partition walls 1 of this invention face each other across the gap 10,
It is a double wall consisting of an inner wall 7a on the side of the air bearing chamber 5 and an outer wall 7b on the side of the high temperature and high pressure air chamber 17, and a large number of ventilation holes 8 are provided in the inner wall 7a so that a gap 10 is formed so that the high temperature and high pressure can be removed from the air bearing chamber 5. Since it serves as a path for low-temperature, high-pressure air to the air chamber 17, it blocks the radiant heat of the high-temperature combustion gas generated in the combustion chamber 11 and reduces the temperature rise in the air bearing chamber 5.

Since the thermal conductivity of air is much lower than that of metals, the constant flow of low-temperature air through the gap 10 is particularly effective in blocking heat radiation from the combustion chamber 11.

Therefore, the amount of low-temperature, high-pressure air required for cooling the air bearing 6 supplied from the compressor 3 can be reduced, resulting in improved turbine efficiency.

In addition, since the air that has cooled the air bearing chamber 5 can be introduced into the combustion chamber 11 through the gap 10 in the partition wall 7 and the high-temperature and high-pressure air chamber 17, the air that has cooled the air bearing chamber 5 can be introduced into the combustion chamber 11 through the gap 10 in the partition wall 7 and the high-temperature and high-pressure air chamber 17. and turbine main shaft 1
The amount of air flowing from the combustion chamber labyrinth seal 16 to the combustion chamber 11 through the air volume button and the combustion chamber labyrinth seal 16 through the back surface of the turbine main shaft 1 can be reduced by reducing the gap between the combustion chamber and the radial turbine 14, thereby improving the output of the gas turbine. and improves fuel efficiency.

[Brief explanation of the drawing]

The figure is a sectional view of one embodiment of this invention in a gas turbine. 2... Centrifugal compressor, 3... Low temperature high pressure air passage, 5... Air bearing chamber, 7... Bulkhead, 7a... Inner wall, 7b... Outer wall, 8
...Vent, 10...Gap, 11...
... Combustion chamber, 17... High temperature and high pressure air chamber.

Claims (1)

[Scope of utility model registration request] The air bearing chamber, which communicates with the compressor outlet via a low-temperature, high-pressure air passage, is divided by a high-temperature, high-pressure air chamber located at the rear of the combustion chamber, and a curved disk-shaped bulkhead, and the gas bearing chamber is located at the rear of the high-temperature, high-pressure air chamber. In a turbine engine, the partition wall is composed of an inner wall on the side of the air bearing chamber and an outer wall on the side of the high-temperature and high-pressure air chamber, which face each other across a gap forming an air exhaust path, and the inner wall has a large number of ventilation holes. The air bearing cooling structure is characterized in that the gap is buttoned at a position of the minimum radius of the partition wall and communicates with a high temperature and high pressure air chamber.