Fluid reaction surfaces (i.e. – impellers) – Specific working member mount – Blade received in well or slot
Reexamination Certificate
2001-09-13
2003-09-16
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific working member mount
Blade received in well or slot
C029S889210
Reexamination Certificate
active
06619924
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to blade elements used in compressor and turbine rotors. More particularly, the invention relates to a blade assembly that can be used to replace damaged blades in the field.
An axial flow compressor comprises a rotor made up of a plurality of wheels attached to a shaft, the wheels providing the compression stages of the compressor. Each compressor wheel is typically an annular disk with a plurality of blade elements attached to its outer rim. The blade elements typically have a blade portion with an airfoil-shaped cross-section and an arrangement for attaching the blade element to the wheel. The attachment arrangement is typically a dovetail-shaped base configured for placement in a correspondingly shaped groove or slot in the wheel.
Compressor rotors rotate at high speeds to compress large volumes of gas. Unfortunately, the gas entering the intake of the compressor may sometimes include solid matter. The compressor blades are therefore subject to occasional damage due to high speed collision with solid particles. Such foreign object damage (FOD) can be severe enough that the damaged blade must be machined or replaced. The components of early (i.e., low pressure) stage compressor wheels/blades are often large enough that damaged blades may be machined in place. Later stage blades, however, typically require removal. Depending on the configuration of the blade attachment arrangement, this can require removal and disassembly of the entire wheel.
SUMMARY OF INVENTION
The present invention provides a replacement blade assembly that allows the replacement of damaged blade elements without removal and disassembly of the rotor.
Accordingly, the present invention provides a blade assembly for installation in a rotor wheel slot having a slot neck in communication with a slot base cavity defined by first and second slot flank walls and a slot floor. The blade assembly comprises a blade element having an airfoil portion and a base portion configured for insertion into the rotor wheel slot through the slot neck. The blade assembly also comprises at least one filler piece configured for insertion into the rotor wheel slot through the slot neck. The at least one filler piece is also configured for positioning intermediate the base portion and the first slot flank wall to secure the base portion within the rotor wheel slot.
The base portion of the blade element of a blade assembly according to the invention may include a base dovetail having first and second dovetail flank surfaces and a dovetail bottom surface. The blade assembly may comprise a first filler piece configured to be positionable with at least a portion of the first filler piece disposed intermediate the first dovetail flank surface and the first slot flank wall. The blade assembly may further comprise a second filler piece configured so that at least a portion of the second filler piece is disposable intermediate the second dovetail flank surface and the second slot flank wall. The at least a portion of the first filler piece may include a first engaging surface adapted for engaging the first slot flank wall and a second engaging surface adapted for engaging the first dovetail flank surface. The at least a portion of the second filler piece may include a third engaging surface adapted for engaging the second slot flank wall and a fourth engaging surface adapted for engaging the second dovetail flank surface. The first and second filler pieces may each include a bottom member configured so that the bottom member is disposed intermediate the dovetail bottom surface and the slot floor. At least a portion of the bottom member may be configured to engage the dovetail bottom surface and the slot floor.
In an embodiment of the invention, the base portion of the blade element may include a base dovetail having first and second dovetail flank surfaces and a dovetail bottom surface. The blade assembly may comprise a first plurality of filler pieces sized and configured to be positionable with at least a portion of each of the first plurality of filler pieces disposed intermediate the first dovetail flank surface and the first slot flank wall. A second plurality of filler pieces may be sized and configured to be positionable with at least a portion of each of the second plurality of filler pieces disposed intermediate the second dovetail flank surface and the second slot flank wall. The at least a portion of each of the first plurality of filler pieces may include a first engaging surface adapted for engaging the first slot flank wall and a second engaging surface adapted for engaging the first dovetail flank surface. The at least a portion of each of the second plurality of filler pieces may include a third engaging surface adapted for engaging the second slot flank wall and a fourth engaging surface adapted for engaging the second dovetail flank surface. Each of the first and second plurality of filler pieces may include a bottom member configured so that the bottom member is disposed intermediate the dovetail bottom surface and the slot floor. The at least a portion of the bottom member may be configured to engage the dovetail bottom surface and the slot floor.
Embodiments of the blade assembly of the invention may comprise a spacer configured for insertion into the rotor wheel slot through the slot neck. The spacer may be further configured for positioning within the rotor wheel slot in abutment with the base portion of the blade element. The spacer may have a spacer dovetail with first and second spacer flank surfaces configured for engagement with the first and second slot flank walls. The blade assembly may further comprise means for securing the spacer in place within the rotor wheel slot. The means for securing may include a threaded fastener having proximal and distal ends. The threaded fastener may be configured for insertion through a corresponding threaded passage in the spacer so that the distal end contacts the floor of the slot dovetail.
An embodiment of the invention provides a blade assembly for installation on a rotor wheel having a blade slot formed in a circumferential rim thereof, the blade slot having a substantially constant cross-section with a slot neck in communication with a slot base cavity having first and second flank surfaces and a floor. The blade assembly comprises a blade element having an airfoil portion and a base portion. The base portion has first and second base flank surfaces and is configured for insertion into the blade slot through the slot neck. The blade assembly further comprises a first filler piece configured to be positionable with at least a portion of the first filler piece disposed intermediate the first base flank surface and the first slot flank wall. The blade assembly also comprises a second filler piece configured so that at least a portion of the second filler piece is disposable intermediate the second base flank surface and the second slot flank wall. At least a portion of the first filler piece may include a first engaging surface adapted for engaging the first slot flank wall and a second engaging surface adapted for engaging the first base flank surface. At least a portion of the second filler piece may include a third engaging surface adapted for engaging the second slot flank wall and a fourth engaging surface adapted for engaging the second base flank surface.
One aspect of the invention provides a blade assembly for installation on a rotor wheel having a blade slot formed in a circumferential rim thereof, the blade slot having a substantially constant cross-section with a slot neck in communication with a dovetail-shaped slot base cavity defined by first and second flank surfaces and a floor. The blade assembly comprises a blade element having an airfoil portion and elongate base portion including a base dovetail having first and second dovetail flank surfaces and a dovetail bottom surface. The base portion is configured for insertion into the blade slot through the slot neck. The blade assembly also comprises a first plur
General Electric Company
Hunton & Williams
Look Edward K.
McCoy Kimya N
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