Fluid reaction surfaces (i.e. – impellers) – Specific working member mount – Blade received in well or slot
Reexamination Certificate
2002-03-05
2003-05-20
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific working member mount
Blade received in well or slot
C416S190000, C416S19300A
Reexamination Certificate
active
06565322
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to a turbomachine including a sealing system for a rotor which extends along an axis of rotation, the rotor including 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 the 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.
GB 905,582 and EP 0 761 930 A1 each describe a turbomachine with a turbine rotor of disk design, in which rotor blades are attached to the rotor disks by means of an axial fir-tree groove connection. Axial fixing of the rotor blades is produced by securing plates which are arranged in a fixed position on the end sides of the rotor disks, it also being possible to achieve a certain sealing action with respect to the penetration of action fluid in the blade root/groove region.
SUMMARY OF THE INVENTION
The invention is based on an object of providing a sealing system for a flow machine. The flow machine preferably includes a rotor which extends along an axis of rotation and includes 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.
According to the invention, an object is achieved by a turbomachine, having a rotor which extends along an axis of rotation. The turbomachine preferably includes 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. Each blade preferably includes 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 receiving structure, so that the blade platform of the first rotor blade and the blade platform of the second rotor blade adjoin one another. Further, a space is preferably formed between the blade platforms and the circumferential face, in which turbomachine a sealing system is provided on the circumferential face in the space.
The invention is based on a consideration that when a turbomachine is operating, the rotor is exposed to a flowing hot action fluid. As a result of the expansion, the hot action fluid applies work to the rotor blades and sets them in rotation about the axis of rotation. Therefore, the rotor with the rotor blades is subject to very high thermal and mechanical loads, in particular on account of the centrifugal forces which occur as a result of the rotation. A coolant, e.g. cooling air, which is usually fed to the rotor through suitable coolant feeds, is used to cool the rotor and in particular the rotor blades. In this case, leaking flows of both coolant and hot action fluid—what are known as gap losses—may occur in the space. A space is in this case formed by the circumferential face, which in this case is defined by the outer radial boundary surface of the rotor and by the platforms, arranged radially outside the circumferential face, of two rotor blades which are arranged next to one another in the circumferential direction of the rotor.
These leaking flows have a very disadvantageous effect on the cooling efficiency and the mechanical installation strength (quiet running and creep rupture strength) of the rotor blades in the receiving structure of the circumferential face. In this context, leaking flows which are oriented along the axis of rotation (axial leaking flows), for example along the circumferential fa
Lieser Dirk
Reichert Arnd
Strassberger Micheal
Tiemann Peter
Harness Dickey & Pierce PLC
Look Edward K.
McAleenan James M
Siemens Aktiengesellschaft
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