WO2000017491A1

WO2000017491A1 - High temperature gas turbine, preferably of a gas turbine engine

Info

Publication number: WO2000017491A1
Application number: PCT/UA1999/000008
Authority: WO
Inventors: Valery Viktorovich Manchesko
Original assignee: Bezrukov, Alexandr Mikhailovich
Priority date: 1998-09-21
Filing date: 1999-04-29
Publication date: 2000-03-30
Also published as: UA31519A; AU4306599A

Abstract

A turbine comprises a stator body with nozzle sets wherein a rotor unit is mounted consisting of an internal shroud connected to the turbine shaft, an external shroud mounted in the stator body groove and a plurality of vanes made of heat-resistant ceramics and located between the internal and external shrouds. It is characterized in that the internal and the external shrouds are made of heat-resistant ceramics with thin walls and rigidly connected to thin-profile vanes, the internal shroud is mounted in the stator body by means of a peripheral radial gas supports and on the turbine shaft by means of peripheral radial gas support and peripheral axial gas supports, the external shroud is mounted in the stator body by means of root radial gas supports and root axial gas supports, the whole blading being made monolithic with a capacity of axial and radial shift, both root radial, root axial gas supports and peripheral radial, circumferential and axial gas supports being hydraulically connected to a source of working high pressure air. The turbine has substantially improved weight and size characteristics, a simpler design and an improved operational stability under transitional conditions.

Description

HIGH TEMPERATURE GAS TURBINE, PREFERABLY OF A GAS

TURBINE ENGINE

The invention refers to engine technology and may be used in manufacture of high temperature gas turbine and steam engines for land vehicles and aircraft as well as at energy-generating plants.

A high temperature turbine is known comprising a stator body with nozzle sets, wherein a rotor unit is installed consisting of an internal shroud connected to the turbine shaft, an external shroud located in a stator body groove and vanes made of heat-resistant ceramics and installed between the internal and the external shrouds (US Patent 5,493,855). The internal shroud supports the rotor unit consisting of a plurality of vanes made of heat-resistant ceramics, fitted to high strength metal spikes which have a composite internal structure and provide a mechanical connection between the external shroud being a massive metal rim and the internal shroud being a massive metal hub. The internal shroud-hub serves to take centrifugal loads emerging during rotation of the rotor unit and the hub itself as well as to translate circumferential loads from the rotor unit to the engine shaft and to take axial loads. Both the internal shroud- hub and the external shroud-rim have a plurality of cavities and borings to create hydrodynamic supports for ceramic vanes which self-center relative to the rotor unit elements. The liquid used in hydrodynamic supports serves to cool metal spikes as well. In this engine the loads taken by ceramic vanes are translated to the rotor unit elements through hydrodynamic supports, thus, without a direct mechanical contact.

The basic disadvantage of the known design is the presence of a large mass of liquid necessary to warrant operation of the hydrodynamic supports. Thereby the rotor elements become too heavy and too bulky. Moreover, the liquid present at the rotor elements may cause rotor disturbance during its rotation, change in spatial position of engine axis as well as in case of the liquid transfer from liquid to gaseous phase under changing thermal and dynamic conditions.

Another disadvantage of this design is taking of centrifugal loads emerging during rotation of the rotor unit by the rotor itself which makes the rotor structure heavier and more complicated.

Still another disadvantage of the design is a necessity of having large amounts of liquid comparable to those of fuel as well as additional systems in order to provide for operation of the rotor liquid systems which is extremely unfavorable while using this engine in a vehicle.

Finally, one can attribute a very complicated structure of the internal and the external shrouds and metal high strength cooled spikes to disadvantages of this rotor.

The object of the present invention is to build a high temperature gas turbine engine of a simpler design, operating without any liquid and, therefore, free from the above-mentioned disadvantages. The main elements of turbine rotor should be made not of high strength, expensive metals with a high specific density, but of cheaper ceramics used in manufacture of turbine rotors and having a low specific density.

The solution lies in the known high temperature gas turbine comprising a stator body with nozzle sets wherein a monolithic rotor unit is installed consisting of an internal shroud connected to the turbine shaft, an external shroud mounted in a stator body groove and vanes made of high temperature ceramics and mounted between the internal and the external shrouds, the internal and the external shrouds being made of high temperature ceramics with thin walls and rigidly connected to thin-profile vanes, the internal shroud is mounted within the stator body using a peripheral radial gas support and on the turbine shaft using peripheral circumferential gas supports and peripheral axial gas supports, the external shroud is mounted within the stator body using root radial gas supports and root axial gas supports, the whole blading being monolithic and able of axial and radial shift, both root radial gas supports and root axial gas supports as well as peripheral radial, circumferential and axial gas supports having a hydraulic connection to a source of high pressure working air.

Preferably each of root radial gas supports is a cavity formed by a cylindrical annular surface of the blading external shroud which is adjacent to the stator body internal annular surface and equipped with sealing elements located on the blading external shroud and on the stator body.

Each of root axial supports is preferably a cavity formed by a radial annular surface on the blading external shroud radial projection and by an adjacent radial annular surface of the stator body and equipped with sealing elements located on the blading external shroud radial projection and on the stator body connected to a source of high pressure air, the cavity located opposite to the radial projection being in communication to the turbine setting.

A peripheral radial gas support may comprise a cavity formed by an annular cylindrical surface of the blading internal shroud and an adjacent cylindrical annular surface of a nozzle set and equipped with sealing elements located on the blading internal shroud and on the nozzle set.

Similarly, a peripheral axial gas support preferably comprises a cavity formed by a radial annular surface on a radial projection of the internal shroud entering a shaft radial annular groove and an adjacent radial annular surface of the shaft groove equipped with sealing elements and connected to a source of high pressure air, the cavity located opposite to the radial projection being in communication to the turbine setting.

Some contact projections may be made on adjacent surfaces of the blading internal shroud and the shaft groove.

A peripheral circumferential gas support preferably comprises a cavity formed by a radial axial surface of axial projection on the blading internal shroud entering into the shaft axial groove and by an adjacent radial axial surface of the shaft axial groove equipped with sealing elements and connected to a source of high pressure air. The cavity opposite to the axial projection of the blading internal shroud is in communication with the turbine setting.

Some contact projections may be made on adjacent surfaces of axial projection of the blading internal shroud and the axial shaft groove.

The invention is explained in more detail by accompanying drawings where:

Fig. 1 is a schematic view of the turbine axial section.

Fig. 2 is a schematic view of the root radial and axial gas supports.

Fig. 3 is a schematic view of peripheral radial and axial gas supports.

Fig. 4 is a schematic view of peripheral circumferential gas supports.

Fig. 5 is a schematic view of the turbine axial section in an alternative embodiment with additional shape-forming elements and dissection places in axial direction specified.

Fig. 6 is a schematic view of axial and radial sections of the turbine with places of radial dissection specified.

In stator body 1 including nozzle sets 2 a monolithic ceramic rotor unit 3 is installed using root radial gas support 4, root axial gas support 5 and peripheral radial gas support 6 (Fig. 1). Rotor unit 3 is also installed on engine shaft 7 using peripheral c cumferential gas supports 8 and peripheral axial gas support 9.

To convey high pressure air to root radial gas support 4 borings 10 are made in stator body 1 at equal distances along its diameter. Borings 1 1 are made in stator body 1 and in the vane part of nozzle set 2 to convey high pressure air to root axial gas support 5 and peripheral radial gas support 6. Borings 12 in turbine shaft 7 convey high pressure air to peripheral gas supports - axial 9 and circumferential 8. Fig. 2 schematically shows a fragment of turbine setting including stator body 1, stator nozzle sets 2, rotor unit 3 as well as root gas supports - radial 4 and axial 5. External shroud 13 of rotor unit 3 forms root radial gas support 4 together with the adjacent annular surface of the first groove in stator body 1 and sealing elements 14, 15 of external shroud 13 of rotor unit 3 as well as with sealing elements 16, 17 of stator body 1. Root axial gas support 5 is formed by the radial annular surface of radial projection 18 from external shroud 13, the adjacent radial annular surface of the second groove in stator body 1 as well as by sealing elements 19, 20 of radial projection 18 from external shroud 13 and by sealing elements 21, 22 of stator body 1. Rear chamber 23 is formed by the opposite radial annular surface of radial projection 18 from external shroud 13 of rotor unit 3 and the adjacent radial annular surface of the second groove in stator body 1, the chamber being in communication to the turbine setting.

Fig. 3 schematically shows peripheral gas supports - radial 6 and axial 9. Peripheral radial gas support 6 is formed by annular cylindrical surface of internal shroud 24 of rotor unit 3, the adjacent annular surface of nozzle set 2 of stator body 1, sealing elements 25, 26 of internal shroud 24 of rotor unit 3 and sealing elements 27, 28 of nozzle set 2 of stator body 1. Peripheral axial gas support 9 is formed by the radial annular surface of radial projection 29 from internal shroud 24 of rotor unit 3 entering into radial groove of engine shaft 7, adjacent radial annular surface of the groove in engine shaft 7, sealing elements 30, 31, 32 of radial projection 29 from internal shroud 24 of rotor unit 3 and sealing elements 33, 34, 35 of engine shaft 7. Contact projection 36 is made on radial projection 29 from internal shroud 24 of rotor unit 3, a similar contact projection 37 being made in the radial groove of engine shaft 7. Rear chamber 38 is formed by the opposite radial annular surface of radial projection 29 from internal shroud 24 of rotor unit 3 and the adjacent opposite radial annular surface of the groove in engine shaft 7, the chamber being in communication to the turbine setting.

Fig. 4 schematically shows peripheral circumferential gas support 8 (along the axis), whereas View B of Fig. 4 schematically shows a plurality of peripheral circumferential gas supports 8 (along the radius). Peripheral circumferential gas support 8 is formed by radial axial surface of axial projection 39 from internal shroud 24 of rotor unit 3, the adjacent radial axial surface of the axial groove of engine shaft 7, sealing elements 40, 41, 42 of axial projection 39 from internal shroud 24 of rotor unit 3 and sealing elements 43, 44, 45 of axial groove in engine shaft 7. Contact projection 46 is made on axial projection 39 from internal shroud 24 of rotor unit 3. A similar contact projection 47 is made in the axial groove of engine shaft 7. Rear chamber 48 is formed by the opposite radial axial surface of axial projection 39 from internal shroud 24 of rotor unit 3 and the adjacent opposite radial axial surface of engine shaft 7, the chamber being in communication to the turbine setting.

Fig. 5 schematically shows an axial section of an alternative embodiment characterized by dissecting rotor unit 3 in axial direction at points 49, 50. Points of dissection 49, 50 as well as points of dissection in radial direction (see Fig. 6) are lapped over by solid shape-forming sealing elements 51, 52, 53.

Fig. 6 is a schematic view of axial and radial sections of the alternative embodiment characterized by dissecting rotor unit 3 into segments in radial directions at points 54, 55 on external shroud 13 and at points 56, 57 on internal shroud 24. The points of dissection of rotor unit 3 on external shroud 13 are overlapped from outside by solid shape-forming sealing element 53.

In the course of rotor unit rotation some tension stresses emerge in its elements under the action of centrifugal forces. To compensate for those stresses high pressure air is conveyed to root radial gas support 4, creating a necessary supporting force evenly distributed all over the surface of external shroud 13 of rotor unit 3 (Figs 1, 2). At this external shroud 13 of rotor unit 3 is subjected to compressive action of ambient air, whereas tension stresses reverse their sign and become compression stresses. The blading of rotor unit 3 rests on external shroud 13 and experiences a compression stress as well. In its turn, the intervane part of internal shroud 24 rests on the vanes and experiences compression stresses (Fig. 3). High pressure air serves as a supporting medium which translates all centrifugal loads from rotor unit 3 to stator body 1. In root axial gas support 4 a part of axial forces from the gas flow acting upon rotor unit 3 is translated to stator body 1 via radial projection 18 from external shroud 13 due to high pressure air. The axial balancing force is equal to difference of forces from pressures at root axial gas support 3 and rear chamber 23 upon radial projection 18 from external shroud 13 and counteracts the gas flow forces. The pressure in rear chamber 23 is equal to pressure jn the turbine setting. High pressure air vented through the seals formed by sealing elements 14, 15, 16 and 17 gets to the engine setting.

Peripheral radial gas support 6 operates similarly to root radial gas support 4 as shown in Fig. 2. Centrifugal forces from rotation of internal shroud 24 of rotor unit 3 are translated by high pressure air via nozzle set 2 to stator body 1. The resultant force from centrifugal forces and air high pressure forces is directed centripetally and causes a compression stress in internal shroud 24 of rotor unit 3. Peripheral radial gas support 6 is equipped with seals formed by sealing elements 27 and 28 located on nozzle set 2 and by sealing elements 25, 26 located on internal shroud 24 of rotor unit 3, high pressure air vented through those seals getting to the turbine setting. Peripheral axial gas support 9 operates similarly to root axial gas support 5, the only difference being that axial forces emerging due to the gas flow acting upon rotor unit 3 are translated to turbine shaft 7 via radial projection 29 from internal shroud 24 of rotor unit 3 using high pressure air. A peculiarity in translation of axial forces by this support is a partial contact action performed by contact projection 36 of radial projection 29 from internal shroud 24 of rotor unit 3 upon contact projection 37 from the radial groove in engine shaft 7. This contact action performs a function of partial unloading of rotor unit 3 from gas flow acting upon the latter as well as additional sealing of peripheral axial gas support 9. The axial balancing force is equal to difference between pressures acting upon radial projection 29 of internal shroud 24 at peripheral axial gas support 9 and at rear chamber 38 and directed opposite to the forces enacted by the gas flow. The pressure in rear chamber 38 is equal to the pressure in the turbine setting. Vented high pressure air gets to the turbine setting via sealing elements 30, 31, 32 at radial projection 29 from internal shroud 24 of rotor unit 3 and via sealing elements 33, 34, 35 of engine shaft 7. The operation of peripheral circumferential gas support is similar to operation of peripheral axial gas supports, the difference being that it is directed along circumference. Rotor unit 3 being acted upon by a lift emerging at its profiled part due to the gas flow moves along its circumference and translates rotation to engine shaft 7 via axial projection 39 from internal shroud 24 of rotor unit 3 using high pressure air. Peripheral circumferential gas supports 8 are unique in having contact projection 46 at radial projection 39 from internal shroud 24 of rotor unit 3, this projection contacting contact projection 47 of axial groove in engine shaft 7 under the action of circumferential forces. Those projections serve for partial unloading of rotor unit 3 from circumferential forces acting upon it as well as for additional sealing of peripheral circumferential gas supports 8. The resultant force from high pressure air acting in peripheral circumferential gas supports 8 and rear chambers 48 upon axial projection 39 partially compensates the action of circumferential forces, its direction being opposite to the latter. Rear chambers 48 are in communication to the turbine setting and the pressure in them is equal to that in the setting. High pressure air vented between sealing elements 40, 41, 42 of axial projection 39 from internal shroud 24 of rotor unit 3 and sealing elements 43, 44, 45 of engine shaft 7 gets to the turbine setting.

An alternative embodiment may be instead of a monolithic ceramic rotor unit a design dissected into segments in radial direction on external shroud 13 (dissection points 54, 55, Fig. 6, Views D, K) and on internal shroud 24 (dissection points 56, 57, Fig. 6, Views D, E), and in axial direction on internal shroud 24 between bladings (dissection points 49, 50, Fig. 5). Such a design makes manufacture of a rotor unit easier but requires use of additional shape-forming and joint-sealing elements: 53 from outside along external shroud 13 of rotor unit 3 (Fig. 5) and 51, 52 from outside along internal shroud 24 of rotor unit 3 (Fig. 5).

The engine is equipped with a high pressure compressor (not shown in the drawings) which creates a necessary pressure of air-carrier medium for all above- mentioned gas supports. In some calculated operational modes of the engine water can serve as a supporting medium; it is fed to the above-mentioned supports and transformed into steam under high temperatures, thus decreasing the consumption of high pressure air.

This design may be used in steam turbines as well.

,' ' *> As compared to the conventional designs the proposed gas turbine has the following advantages:

a) the rotor unit is made of heat-resistant ceramics with a relatively small density which decreases the weight of the structure;

b) use of ceramics instead of alloyed steels makes a turbine substantially cheaper;

c) the design of the rotor unit is much simpler;

d) the structure does not require any cooling system;

e) use of high temperatures at the turbine input allows to substantially decrease the turbine size while preserving the same capacity;

f) any leaks of supporting medium in the turbine have been excluded;

g) this design does not allow any circulation between vanes, thus improving aerodynamic characteristics of the turbine stage;

h) no thermal corrosion of the rotor unit is observed;

i) the size and weight of engine shaft support units are relatively small;

j) fuel is burned more efficiently, thus the turbine becomes more environment- friendly.

The advantages of the proposed gas turbine as compared to the known turbine with ceramic blading are as follows: 1) the turbine weight and size are substantially smaller, its capacity remaining unchanged;

2) the design of rotor unit is much simpler;

3) the consumption of high pressure air is negligible - under 1.5 % of total value; >

4) the weight and size characteristics of rotating parts have been substantially improved;

5) under transitional conditions connected to the rotor unit rotation axis changing its position relative to the engine rotation axis and then retiirning to its initial position due to gas dynamic properties in gas supports free to be manifested.

Claims

1. High temperature gas turbine, particularly of a gas turbine engine, comprising a stator body with nozzle sets, wherein a rotor unit is mounted consisting of an internal shroud connected o the turbine shaft, an external shroud mounted within a groove in a stator body and vanes made of heat-resisting ceramics and installed between the internal and the external shrouds, characterized in that the internal and the external shrouds are made of heat-resistant ceramics with thin walls and rigidly connected to thin-profile vanes, the internal shroud is mounted in the stator body by means of peripheral radial gas support and on the turbine shaft by means of peripheral radial gas supports and peripheral axial gas supports, the external shroud is mounted in the stator body by means of root radial gas supports and root axial gas supports, the whole blading being made monolithic with a capacity of axial and radial shift, both root radial, root axial gas supports as well as peripheral radial, circumferential and axial gas supports being hydraulically connected to a source of working high pressure air.

2. High temperature gas turbine according to claim 1, characterized in that the root radial gas support comprises a cavity formed by a cylindrical annular surface of the blading external shroud adjacent to the internal annular surface of the stator body and is equipped with sealing elements located in the blading external shroud and the stator body.

3. High temperature gas turbine according to claim 1, characterized in that the root axial support comprises a cavity formed by a radial annular surface on a radial projection from the blading external shroud and the adjacent radial annular surface of the stator body and is equipped with sealing elements located on a radial projection from the blading external shroud and on the stator body and is connected to a source of high pressure air, the cavity opposite to the radial projection being in communication with the turbine setting.

4. High temperature gas turbine according to claim 1, characterized in that the peripheral radial gas support comprises a cavity formed by an annular cylindrical surface of the blading internal shroud and the adjacent annular cylindrical surface of a nozzle set and is equipped with sealing elements located on the blading internal shroud and on the nozzle set.

5. High temperature gas turbine according to claim 1, characterized in that the peripheral axial gas support comprises a cavity formed by a radial annular surface on a radial projection from the internal shroud entering into a radial annular groove on the shaft and the adjacent radial annular surface of the groove on the shaft equipped with sealing elements and connected to a source of high pressure air, the cavity opposite to the radial projection being in communication to the turbine setting.

6. High temperature gas turbine according to claims 1, 5, characterized in that contact projections are made on the adjacent surfaces of the radial projection of the blading internal shroud and the shaft groove.

7. High temperature gas turbine according to claim 1, characterized in that the peripheral circumferential gas support comprises a cavity formed by a radial axial surface of an axial projection on the blading internal shroud entering into the shaft axial groove and the adjacent radial axial surface of the shaft axial groove equipped with sealing elements and connected to a source of high pressure air, the cavity opposite to the axial projection of the blading internal shroud being in communication to the turbine setting.

8. High temperature gas turbine according to claims 1, 7, characterized in that contact projections are made on adjacent surfaces of the axial projection of the blading internal shroud and of the shaft axial groove.