US20160327065A1

US20160327065A1 - Rotor drum for a turbomachine and compressor

Info

Publication number: US20160327065A1
Application number: US15/091,320
Authority: US
Inventors: Stefan Boewing
Original assignee: MTU Aero Engines AG
Current assignee: MTU Aero Engines AG
Priority date: 2015-05-07
Filing date: 2016-04-05
Publication date: 2016-11-10
Also published as: EP3091178A1

Abstract

A rotor drum (100) for a turbomachine, the rotor drum (100) including portions of at least a first rotor main body (3) and a second rotor main body (5), and the second rotor main body (5) having at least one rotor arm (7) is provided. The rotor drum (100) has at least one opening (1) as a passage opening for allowing fluids to pass therethrough from an inner rotor space (22) to an outer rotor space (23), the opening (1) being disposed radially outwardly at the greatest radius (19) of an inner contour (21) of the rotor drum (100). A compressor is also provided.

Description

This claims the benefit of European Patent Application EP15166681.5, filed May 7, 2015 and hereby incorporated by reference herein.
The present invention relates to a rotor drum for a turbomachine.

BACKGROUND

In turbomachine rotors, liquid accumulations may occur in certain operating situations and may collect in cavities of rotor drums due to centrifugal force during the operation of the rotors. It is only when the rotors are at rest that this accumulated liquid may flow into other regions of the rotors and possibly cause various disadvantages. For example, when the rotor is restarted, oil in liquid form may be distributed to regions of the turbomachine where such oil accumulations result in considerable disadvantages. In a possible application of the turbomachine as an aircraft engine, the oil may, for example, enter the cabin supply air through casing channels after restarting of the rotors, and there result in oil smell and contaminations.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a rotor drum for a turbomachine, in which fluid accumulations can be prevented. It is also an object of the present invention to provide a compressor.
The present invention provides a rotor drum for a turbomachine, the rotor drum including portions of at least a first rotor main body and a second rotor main body. The second rotor main body has at least one rotor arm. The rotor drum further has at least one opening as a passage opening, in particular as a hole, for allowing fluids, in particular bearing oil or condensed bearing oil mist of a rotor bearing, to pass therethrough from an inner rotor space to an outer rotor space. The opening is disposed radially outwardly with respect to the main flow axis of the turbomachine. Furthermore, the opening is disposed at the greatest radius of an inner contour of the rotor drum. It can thus advantageously be achieved that, during operational rotation of the rotor drum, bearing oil collects at the opening and is spun off from the rotor drum into the main flow passage due to centrifugal force. The spun-off oil can be carried with the main flow out of the turbomachine and discharged therefrom.
Advantageous refinements of the present invention are the subject matter of the respective specific embodiments, for example.
Specific exemplary embodiments of the present invention may include one or more of the features mentioned below.
The term “rotor,” as used herein, refers to a rotating body in a turbomachine, which rotates about an axis of rotation of the turbomachine during normal operational use. The rotor includes at least one rotor stage. A rotor stage may be referred to as a blade wheel or include a blade wheel. A rotor stage includes at least a plurality of rotor blades and a rotor main body. The rotor main body may be referred to as, or include, a disk, rotor disk, ring, or rotor ring. A rotor may have one or more rotor stages.
A rotor may be mounted and installed in a turbomachine, in particular in a gas turbine. An aircraft engine may be a gas turbine or include a gas turbine. An aircraft engine may include a compressor having a plurality of compressor stages and a turbine having a plurality of turbine stages. Compressor stages and turbine stages may each have rotor stages and stator stages.
The rotor blades may be referred to as blades and each have at least an airfoil portion, a root portion and a platform portion. The blades may be connected to the rotor main body either integrally therewith or separately, for example, form-fittingly by means of releasable connections known as dovetail connections. Separate blades may be connected to the rotor main body either releasably and/or form-fittingly and/or by a material-to-material bond. An integral connection is, in particular, a material-to-material bond. An integral connection may be produced using an additive manufacturing process. A rotor main body having blades integrally connected therewith may be referred to as integrally bladed rotor. An integrally bladed rotor may be what is known as a BLISK (bladed disk) or a BLING (bladed ring).
The rotor main body may include radially inwardly directed rotor disks and/or axially oriented rotor arms. The radially inwardly directed rotor disks may be referred to as extensions or T-shaped extensions of the rotor blades.
The rotor arms may be referred to as drum members. The rotor is designed or prepared for direct or indirect connection to a shaft of the turbomachine. An indirect connection may be via a hub and/or via further rotors. In the case of a direct connection, the rotor may be flange-mounted directly to the shaft.
The term “rotor drum,” as used herein, refers to sections of at least two axially interconnected rotor main bodies. In particular, rotor arms may form a rotor drum. A rotor drum may also be configured to extend over more than two rotor main bodies, and optionally over a plurality of rotor arms and rotor disks. For example, a plurality of rotor main bodies of an eight-stage compressor in a turbomachine may form one rotor drum.
The terms “inner rotor space” and “outer rotor space,” as used herein, refer to the spaces inside and outside of the rotor drum of rotors. Thus, the inner rotor space is radially outwardly bounded essentially by one or more rotor arms. The inner rotor space is axially bounded essentially by rotor disks. Generally, a gap is formed between a shaft to which the rotor drum is directly or indirectly connected and the rotor disks. The outer rotor space is radially inwardly bounded essentially by one or more rotor arms. The outer rotor space substantially includes the main flow passage of the turbomachine. Furthermore, between a rotor arm and the main flow passage, there may be disposed, for example, inner stator rings, either with or without abradable seals. The inner rotor space and/or the outer rotor space may include a plurality of rotor stages.
Rotor main bodies arranged axially one behind the other may be interconnected by rotor arms and/or rotor disks. The connection is, in particular, by form-fitting engagement and/or frictional engagement.
Annular balancing collars may be disposed inside the rotor drum, in particular on the inner surface of the rotor arms. The balancing collars may be connected to the rotor arms by frictional engagement. Alternatively or additionally, further balancing devices, such as flanges having balancing weights mounted circumferentially therearound, may be disposed inside the rotor drum.
In several embodiments of the present invention, the turbomachine is an axial turbomachine, in particular a gas turbine, and, more particularly, an aircraft gas turbine.
The rotor drum according to the present invention may be adapted for use in a high-pressure compressor, in a low-pressure compressor, in a high-pressure turbine, or in a low-pressure turbine of an aircraft engine.
A rotor arm may have one or more openings. The openings may be disposed either radially (perpendicularly to the centerline of the rotor drum) or at a different angle in or on the rotor arm. The openings open toward the inner rotor drum space and toward the outer rotor drum space, and provide a port between these two spaces or regions. Thus, the opening penetrates the rotor arm in a direction from radially inward to radially outward.
The opening at the radially widest or greatest radius of the inner contour of the rotor drum may advantageously allow or cause fluids, in particular bearing oil, to flow out of the rotor drum into the outer rotor drum space (radially outside of the rotor drum) due to centrifugal force during rotation, in particular during normal operational use of the rotor drum. For example, when the rotor drum according to the present invention is used in an aircraft engine, it is possible to eliminate, or at least reduce, the risk of oil flowing from the rotor drum into the engine casing after a standstill of the engine. When the aircraft engine is restarted, this oil in the engine casing could then enter the supply air to the cabin and thus contaminate the cabin air.
The inner space of the rotor drum is particularly configured such that oil accumulations resulting from centrifugal force may flow off or escape through one or more openings into the outer space of the rotor drum. The inner space is in particular fluidically optimized for this purpose.
In several embodiments of the present invention, bearing oil in the bearing region, for example in a so-called front-hub and/or rear-hub bearing assembly of a rotor, may evaporate due to increased frictional heat in the bearing and may then condense in the inventive rotor drum. The condensation process may occur in particular in a rotor drum that is located in the immediate vicinity of the bearing. During operation of the turbomachine; i.e., during rotation of the rotor drum, the condensed bearing oil may escape, i.e., be thrown out into the main flow passage, through the radial opening of the inventive rotor drum, and may then advantageously exit the turbomachine with the main flow. Thus, when the turbomachine is started after a temporary stoppage, oil which has accumulated in the rotor drum in cavities can advantageously be prevented from escaping and then entering the bleed air tapped or bled off from the main flow due to low rotational speeds and a low flow rate of the main flow. The bleed air provided, inter alia, for the cabin air in aircraft could be contaminated by entrained oil.
In some embodiments of the present invention, bearing oil mist may escape through the radial opening of the inventive rotor drum. During operation of the turbomachine, the bearing oil mist may escape into the main flow passage and exit the turbomachine with the main flow.
In certain embodiments of the present invention, the rotor arm has at least one sealing tip to form a clearance seal with respect to a stator. The stator may be a stator stage or a stator vane assembly, in particular a stator vane assembly having variable stator vanes.
In several embodiments of the present invention, the opening is disposed axially between the at least one sealing tip and a radially inwardly oriented rotor disk of the second rotor main body.
In some embodiments of the present invention, the at least one rotor arm of the inventive rotor drum has a balancing ring. In particular, the balancing ring is disposed radially outwardly on the rotor arm. A balancing ring that is disposed radially outwardly on the rotor arm advantageously makes it possible to prevent cavities inside the rotor drum.
A balancing ring may be referred to as a balancing collar.
In several embodiments of the present invention, the balancing ring is disposed at the upstream and/or downstream end or end portion of the rotor arm. The terms “upstream” and “downstream” refer to the main flow direction of the turbomachine. The end portion or portions of the rotor arms may be portions for connection to further components of the turbomachine. In particular, the end portions may be form-fittingly connected to further rotor main bodies. The end portions may also be flange-mounted to further rotor main bodies by means of threaded connections. An end portion of a rotor arm may have a balancing ring and at the same time be form-fittingly connected to a further rotor disk. Such an end portion may be referred to as an integral end portion, since it implements two functions at the same time, namely a balancing function and a connecting function.
In some embodiments of the present invention, a rotor main body not having a rotor arm does not have a balancing device. A balancing device may be, for example, a balancing ring or balancing weights disposed on a flange.
In certain specific embodiments according to the present invention, the balancing ring is connected to the rotor arm by frictional engagement. A frictional connection may be achieved, for example, by shrink-fitting. A frictional connection may be an interference-fit connection. In particular, the connection of the balancing ring to the rotor arm does not have a threaded connection. A balancing ring mounted by means of a frictional connection may advantageously be balanced using a material-removal process, such as milling, drilling or grinding, without having to remove the balancing ring from the rotor arm.
In certain specific embodiments according to the present invention, the balancing ring is connected to the rotor arm by a material-to-material bond. A material-to-material bond is, for example, an adhesive bond, a welded connection or a connection produced by means of an additive manufacturing process.
In some embodiments of the present invention, the rotor arm is made from or contains a first material. The balancing ring may be made from or contain a second material. The first material and the second material are different. This advantageously makes it possible, for example, to simplify shrink-fitting of the balancing ring onto rotor arm and/or removal of material from the balancing ring for balancing purposes.
In several embodiments of the present invention, the balancing ring has on its periphery at least one region for material removal for balancing of the rotor. Examples of material-removal processes for removal of material from the balancing ring include milling, drilling and grinding.
The term “balancing device” may include one or more balancing rings, one or more balancing weights, as well as other devices for balancing or counterbalancing a component.
Some or all of the embodiments of the present invention may have one, several or all of the advantages mentioned above and/or hereinafter.
The rotor drum according to the present invention advantageously makes it possible to prevent oil accumulations, for example, accumulations of bearing oil, inside the rotor drum. In a rotating rotor drum according to the present invention, bearing oil or bearing oil mist can be carried directly through the opening at the greatest radius of the inner contour of the rotor drum into the main flow through the stator vanes and rotor blades, and passed on to the outlet of the turbomachine. This quick removal makes it possible to at least reduce a potential fire hazard posed by the oil. It is advantageously possible to prevent oil from accumulating and/or oil mist from condensing while the rotor drum is at rest, and to prevent oil from subsequently being carried from the main flow into branches for the bleed air, for example for the cabin air in aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which identical or similar components are indicated by the same reference numerals. The figures are simplified schematic views in which:

FIG. 1 is a cross-sectional view of an inventive rotor drum having two rotor main bodies, one rotor arm, and a spin-off hole; and

FIG. 2 is a view showing another rotor drum according to the present invention, where the spin-off hole is arranged differently than in FIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows, in cross-sectional view, an inventive rotor drum 100 having an opening as a spin-off hole 1, a first rotor main body 3, a second rotor main body 5, a rotor arm 7, and a balancing ring 9. Spin-off hole 1 is an opening of rotor drum 100 in its radially outward boundary. Rotor drum 100 has a radially inwardly open shape.
Rotor drum 100, which is open radially inwardly (in a direction opposite to radial direction r toward axis of rotation 11 of rotor drum 100), is bounded in axial direction a by a first rotor disk 13 and a second rotor disk 15. The two rotor disks 13, 15 are sections of the two rotor main bodies 3, 5. First rotor disk 13 is disposed at the upstream end and second rotor disk 15 is disposed at the downstream end. Main flow direction 17 is indicated by an arrow.
Spin-off hole 1 is disposed at the greatest radius 19 of an inner contour 21 of rotor drum 100.
Further spin-off holes 1 (not shown in FIG. 1) may be disposed, in particular, in rotor arm 7.
In other embodiments, rotor drum 100 may extend further in the upstream direction and/or in the downstream direction and may include further rotor arms. Also, further spin-off holes may be disposed in the further rotor arms. For example, a multi-stage high-pressure compressor (or low-pressure compressor, high-pressure turbine, low-pressure turbine) of an aircraft engine may include one rotor drum.
During rotation of rotor drum 100 about axis of rotation 11 (during intended operation of rotor drum 100, for example, in an aircraft engine), bearing oil, bearing oil mist or other fluids can be carried from rotor drum 100 through spin-off hole 1 into an outer rotor space 23. Such removal or draining of a fluid is due to or caused by the centrifugal force of the fluid. The flow properties are influenced by viscosity and temperature, for example. Furthermore, the flow of a fluid out of rotor drum 100 into outer rotor space 23 is influenced by the size of a cross section (or diameter) of spin-off hole 1.
Furthermore, in the exemplary embodiment of FIG. 1, balancing ring 9 is disposed on the outer surface of rotor drum 100 (as viewed in radial direction r). This makes it easier for oil present in rotor drum 100 to flow off through flow-out hole 1. If balancing ring 9 were disposed on rotor arm 7 on the inner surface of rotor drum 100 (not illustrated in FIG. 1), the oil could be dammed up in inner rotor space 22 due to centrifugal force. This dammed-up oil would then not flow off into the inner space until rotor drum 100 is at rest. When rotor drum 100 is set into rotation again, this oil could then escape through spin-off hole 1. In this process, due to operational conditions, oil from outer rotor space 23 could enter the cabin air of an aircraft with the bleed air that is tapped or bled off from the main flow, and could cause contamination. This risk of contamination is advantageously prevented, or at least reduced, by disposing balancing ring 9 on the outer surface of rotor drum 100.
In the region of balancing ring 9, first rotor main body 3 is form-fittingly connected to second rotor main body 5 via rotor arm 7 (as indicated by dashed-line circle 25).
In the exemplary embodiment of FIG. 1, rotor main bodies 3, 5 are integrally connected to rotor blades 27. Furthermore, rotor arm 7 has sealing tips 29 which may form a gap with an abradable seal 31 that minimizes leakage flow between rotor drum 100 and a stator vane assembly 200. Abradable seal 31 is connected to an inner ring 33. Inner ring 33 is connected to variable stator vanes 35 of stator vane assembly 200. Stator vanes 35 are mounted and supported rotatably about their longitudinal axis by means of an inner trunnion 37.
FIG. 2 shows another rotor drum 100 according to the present invention, where spin-off hole 1 is arranged differently than in FIG. 1. The longitudinal orientation of spin-off hole 1 is perpendicular to the centerline of rotor drum 100.

LIST OF REFERENCE NUMERALS

100 rotor drum
200 stator vane assembly
a axial; axial direction
r radial; radial direction
1 spin-off hole
3 first rotor main body
5 second rotor main body
7 rotor arm
9 balancing ring
11 axis of rotation
13 first rotor disk
15 second rotor disk
17 main flow direction
19 greatest radius of the inner contour of the rotor drum
21 inner contour of the rotor drum
22 inner rotor space
23 outer rotor space
25 form-fitting connection
27 rotor blade
29 sealing tips
31 abradable seal
33 inner ring
35 variable stator vane
37 inner trunnion

Claims

What is claimed is:

1. A rotor drum for a turbomachine, the rotor drum comprising:

portions of at least a first rotor main body and a second rotor main body, the second rotor main body having at least one rotor arm, and

at least one opening as a passage opening for allowing fluids to pass therethrough from an inner rotor space to an outer rotor space, the opening being disposed radially outwardly at a greatest radius of an inner contour of the rotor drum.

2. The rotor drum as recited in claim 1 wherein the rotor arm includes the opening.

3. The rotor drum as recited in claim 1 wherein the rotor arm has at least one sealing tip to form a clearance seal with respect to a stator.

4. The rotor drum as recited in claim 3 wherein the opening is disposed between the at least one sealing tip and a radially inwardly oriented rotor disk of the second rotor main body.

5. The rotor drum as recited in claim 1 wherein a balancing ring is disposed radially outwardly on the rotor arm.

6. The rotor drum as recited in claim 5 wherein the balancing ring is disposed at the upstream or downstream end portion of the rotor arm of the second rotor main body.

7. The rotor drum as recited in claim 1 wherein the first and second rotor main bodies are prepared for receiving rotor blades to form a first and a second rotor stage.

8. A compressor of a turbomachine, the compressor comprising at least one rotor drum as recited in claim 1.

9. The compressor as recited in claim 8 wherein the compressor is a high-pressure compressor of an aircraft engine.