Fluid reaction surfaces (i.e. – impellers) – Rotor having flow confining or deflecting web – shroud or... – Axially extending shroud ring or casing
Reexamination Certificate
2002-02-28
2004-01-27
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Rotor having flow confining or deflecting web, shroud or...
Axially extending shroud ring or casing
C416S21900R, C416S248000, C416S215000, C416S216000, C416S095000, C416S09600A
Reexamination Certificate
active
06682307
ABSTRACT:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/DE00/01550 which has an International filing date of May 15, 2000, which designated the United States of America, the entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
The invention generally relates to a turbomachine. In particular, it relates to a gas turbine, preferably one including a sealing system for a rotor which extends along an axis of rotation. Even more preferably, the rotor includes a first rotor blade and a second rotor blade which adjoins the first rotor blade in the circumferential direction of the rotor.
BACKGROUND OF THE INVENTION
Rotatable rotor blades of turbomachines, for example of turbines or compressors, are secured in various designs over the entire circumference of the circumferential face of a rotor shaft which is formed, for example, by a rotor disk. A rotor blade usually has a main blade, a blade platform and a blade root with a securing structure which is fitted to the circumferential face of the rotor shaft in a suitably complementary recess, which is produced, for example, as a circumferential groove or an axial groove, so that the rotor blade is fixed in this way.
For design reasons, after the rotor blades have been inserted into the rotor shaft, gaps are formed by the regions which adjoin one another, and in operation of a turbine these gaps give rise to leaking flows of coolant or of a hot action fluid which drives the rotor. Such gaps occur, for example, between two adjacent blade platforms of rotor blades which adjoin one another in the circumferential direction and between the circumferential face of the rotor shaft and a blade platform which radially adjoins the circumferential face. To limit the possible leaking flows, such as for example the escape of coolant, e.g. of cooling air, into the flow channel of a gas turbine, intensive searches are being made for suitable sealing concepts which are able to withstand the temperatures which occur and the mechanical load caused by the considerable centrifugal forces acting on the rotating system.
DE 198 10 567 A1 has disclosed a sealing plate for a rotor blade of a gas turbine. If cooling air which is fed to the rotor blade escapes into the flow channel, this leads, inter alia, to a reduction in the efficiency of the gas turbine. The sealing plate, which is inserted into a gap between the blade platforms of adjacent rotor blades, is intended to prevent the leaking flows caused by the escape of cooling air. The sealing is produced not only by said sealing plate but also by various sealing pins which are likewise fitted between the blade platforms of two adjacent rotor blades. A multiplicity of sealing elements are required in order to achieve the desired sealing action preventing cooling air from escaping from the adjacent blade platforms.
U.S. Pat. No. 5,599,170 has described a sealing concept for a rotor blade of a gas turbine. A substantially radially extending gap and a substantially axially extending gap are formed by two rotor blades which adjoin one another and are attached to the circumferential face of a rotor disk which can rotate about an axis. A sealing element seals the radial gap and, at the same time, the axial gap. For this purpose, the sealing element is inserted into a cavity which is formed by the blade platforms of the rotor blades. The sealing element has a first sealing face and a second sealing face which respectively adjoin the axial gap and the radial gap.
Moreover, the sealing element has a thrust face which extends obliquely with respect to the radial direction. The thrust face directly adjoins a reaction face which is formed as a partial area of a moveable reaction element arranged in the cavity. The sealing action is produced by the centrifugal forces acting on the moveable reaction element as a result of the rotation of the rotor disk. The reaction element transmits to the inclined thrust face a force, the radially directed component of which acts on the sealing element, so that the first sealing face seals the axial gap, while the axially oriented component of the force on the sealing element leads to the second sealing face sealing the radial gap. This sealing concept is unable to prevent cooling air from escaping into the flow passage of the gas turbine along the circumferential face of the rotor disk through gaps which are formed between the circumferential face of the rotor disk and a blade platform of a rotor blade which radially adjoins the circumferential face.
Similarly complex arrangements with one or more sealing elements, as are described in DE 198 10 567 A1 or U.S. Pat. No. 5,599,170, are also used in a turbomachine to prevent a flowing, hot action fluid, e.g. a hot gas or vapor, from entering gap regions and spaces in a rotor. Penetrating action fluid of this type could lead to considerable damage to the rotor blade. To reduce this risk, generally a plurality of sealing elements are inserted into the blade platform on that side of the blade platform of the rotor blade which faces the flow of action fluid.
EP 0 761 930 A1 and GB 905,582 each describe a turbomachine with a turbine rotor. The turbine rotor is in this case of disk design and is composed of individual rotor disks which are arranged axially adjacent to one another. Rotor blades, which are each secured by means of their blade root in an axial groove in the rotor disk, e.g. an axial fir-tree groove or a hammerhead groove, are arranged on the circumference of the rotor disks. Axial fixing of the rotor blades in the blade root/groove region is effected by securing plates which are mounted in a fixed position on the end sides of the rotor disks. The end-side securing plates can also be used to achieve a certain sealing action with respect to possible penetration of action fluid, for example, a hot gas, in the blade root/groove region. However, the securing plates serve primarily to fix the rotor blades in the axial direction.
GB-A-2 280 478 has disclosed a gas-turbine rotor which has sealing arrangements. In one configuration, the sealing arrangement has sealing points which are arranged on the rotor surface and bear in a sealed manner against a radially inwardly arranged sealing face of a turbine guide vane.
U.S. Pat. No. 4,878,811 has disclosed a rotor blade arrangement of an axial compressor. The rotor blade arrangement is produced by a rotor disk with circumferential groove, a multiplicity of compressor rotor blades being secured in the groove over the entire circumference of the rotor disk, so that a ring of rotor blades is formed. Furthermore, a sealing ring is arranged in a sealing groove over the entire circumference of the rotor disk, resulting in a substantially sealed connection between the rotor disk and the platform of the rotor blade.
SUMMARY OF THE INVENTION
The invention is based on an object of providing a highly efficient sealing system for a turbomachine, preferably one including a rotor which extends along an axis of rotation and has a first rotor blade and a second rotor blade which adjoins the first rotor blade in the circumferential direction of the rotor. The sealing system is in particular intended to actively limit the possible leaking flows through gap regions and spaces of the rotor and to be able to withstand the thermal and mechanical loads which occur. In addition, the sealing system is preferably to be designed in such a way that it can be produced as easily as possible and can be employed for various rotors.
According to the invention, an object is achieved by a turbomachine, preferably a gas turbine, including a rotor which extends along an axis of rotation, comprising a circumferential face, which is defined by the outer radial boundary surface of the rotor, and a receiving structure, as well as a first rotor blade and a second rotor blade, which each have a blade root and a blade platform which adjoins the blade root, the blade root of the first rotor blade and the blade root of the second rotor blade being inserted into the r
Harness & Dickey & Pierce P.L.C.
Verdier Christopher
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