Fluid reaction surfaces (i.e. – impellers) – Specific working member mount – Blade received in well or slot
Reexamination Certificate
2001-12-07
2003-06-10
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific working member mount
Blade received in well or slot
C416S248000, C416S500000
Reexamination Certificate
active
06575704
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to a fluid-flow machine. More preferably, it relates to a fluid flow machine including a rotor which extends along a rotation axis. The rotor preferably includes a rotor-shaft slot and a moving blade having a blade root which is inserted into the rotor-shaft slot, and a gap being formed between the blade root and the slot root surface. The invention also generally relates to a sealing element for a rotor of a fluidflow machine.
BACKGROUND OF THE INVENTION
Rotatable moving blades of fluid-flow machines, for example of gas or steam turbines or compressors, are fastened in different configurations over the full circumference to the circumferential surface of a rotor shaft, which, for example, has a rotatable moving disk. A moving blade in this case normally has a blade body, a blade platform and a blade root having a fastening structure which is accommodated by a rotor-shaft slot configured in a corresponding complementary manner for fixing the moving blade. In this case, the rotorshaft slot may be produced as a circumferential slot or axial slot on the circumferential surface of the rotor shaft. The rotor-shaft slot has a slot root surface.
Due to the design, after the blade root of a moving blade has been inserted into the rotor-shaft slot, a gap is formed by the rotor components adjacent to one another in each case. During operation of the rotor, the gap gives rise to leakage flows of cooling medium or of an action fluid driving the rotor through the gap. Such a gap is formed between the blade root and the slot root surface. A gap of this type may also occur between two adjacent blade platforms of moving blades which are adjacent in the circumferential direction and between the circumferential surface of the rotor shaft and a blade platform radially adjoining the circumferential surface.
In order to limit the possible leakage flows through the gap, such as, for instance, the escape of cooling medium, e.g. cooling air, into the flow passage of a gas turbine, intensive searches are being made for effective sealing concepts. These sealing concepts must be resistant to the temperatures which occur and to the mechanical loading as a result of the considerable centrifugal forces on the rotating system.
DE 198 10 567 A1 discloses a sealing plate for a moving blade of a gas turbine. If cooling air which is fed to the moving blade escapes into the flow passage, 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 two adjacent moving blades, is intended to prevent the leakage flows resulting from the escape of cooling air. An additional sealing effect is achieved by sealing pins which are likewise fitted between the blade platforms of two adjacent moving blades. A multiplicity of sealing pins are required in order to achieve the desired sealing effect to prevent the escape of cooling air from the adjacent blade platforms.
A sealing concept for a rotor of a gas turbine having a moving disk and a moving blade cooled in the interior is described in U.S. Pat. No. 4,021,138. The moving disk has a front face, a rear face located opposite the front face along the rotation axis, and an axial moving-disk slot which extends from the front face into the rear face. The moving blade has a blade root which is accommodated by the axial moving-disk slot. In the moving disk, a cooling-medium chamber is adjacent to the blade root in a radially inward direction and passes completely through the moving disk in the axial direction from the front face up to the rear face.
Provided in the moving blade are cooling-medium passages which extend from the blade root up to the blade body in the radial direction and are in fluidic connection with the cooling-medium chamber, so that, for the internal cooling of the moving blade, a cooling medium passes from the cooling-medium chamber into the cooling-medium passages. For this purpose, a cooling medium is admitted to the cooling-medium chamber via a cooling-medium feed arranged axially upstream of the front face. In order to seal the cooling-medium chamber against an escape of cooling medium, a first sealing plate is arranged on the front face and a second sealing plate is arranged on the rear face of the moving disk. For improved sealing, that side of the first sealing plate which faces the front face has a passage which extends in the circumferential direction of the moving disk and opens toward the front face.
The passage is defined in the radial direction by an outer marginal region arranged radially outward and by an inner marginal region located opposite the outer marginal region and arranged radially inward, the outer and inner marginal regions adjoining the front face. The outer marginal region is configured in such a way that, as a result, that part of the passage which adjoins the front face is inclined in a direction relative to the normal of the front face, this direction having a radially outward component. A sealing rod which extends in the circumferential direction is inserted into the passage in such a way as to be movable.
During operation of the rotor, the sealing rod, under the effect of centrifugal force, moves radially outward in the passage along the outer marginal region and in a direction toward the front face, where it finally assumes its sealing position. In the sealing position, the sealing rod is in contact with the front face and seals a gap which is formed between the front face and that side of the sealing plate which faces the front face. This is intended to largely prevent cooling medium from escaping through the gap from the cooling-medium chamber or the cooling-medium feed. This solution is very costly due to the use of the relatively extended sealing plates and the additional sealing rods. Furthermore, maintenance and repair work on the moving blade is only possible after complete removal of these sealing components from the rotor.
EP 0 799 974 A2 discloses a sealing element for a moving blade of a turbomachine. In this case, the turbomachine has a rotor with a rotor disk arranged radially inward, a multiplicity of moving blades being fastened radially outward to the rotor disk in the circumferential direction of the rotor disk with a respective gap being formed. To cool the rotor, cooling passages are provided which extend in the radial direction through the rotor disk and the moving blades.
In order to limit an escape of cooling medium (leakage) from the gap in the region of the blade fastening, a sealing element is arranged between the blade root and the rotor disk. The sealing element, under the effect of centrifugal force, performs a tilting movement and thereby reaches its sealing position. In order to secure the sealing element in the direction of the rotation axis in such a way as to prevent it from falling out of the gap, the sealing element has two securing teeth which enclose a projection, formed radially inward, in the blade root, the sealing element, in particular one of the securing teeth, projecting at least partly from the gap at the front face of the rotor disk.
SUMMARY OF THE INVENTION
An object of the invention is to specify a fluid-flow machine including a rotor which has a rotor-shaft slot and a slot root surface and a moving blade with a blade root, the blade root being inserted into the rotor-shaft slot, with a sealing element. Preferably, the sealing element is intended to make it possible to efficiently limit axial leakage flows and is to be as resistant as possible to the mechanical and thermal loads which occur. A further object of the invention is to specify a sealing element, in particular for a rotor of a fluid-flow machine.
According to the invention, the first-mentioned object is achieved, for example, by a fluid-flow machine including a rotor which extends along a rotation axis and has a rotor-shaft slot having a slot root surface and a moving blade having a blade root, the blade root being inserted into the rotor-shaft slot, and a gap being fo
Harness Dickey & Pierce PLC
McAleenan James M
Siemens Aktiengesellschaft
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