The present invention generally relates to a compressor diaphragm and vane configuration. More specifically, the compressor vane diaphragm includes improved assembly techniques that reduces operating stresses and wear at mating surfaces between adjacent compressor vanes.
Gas turbine engines operate to produce mechanical work or thrust. Specifically, land-based gas turbine engines typically have a generator coupled thereto for the purposes of generating electricity. A gas turbine engine comprises an inlet that directs air to a compressor section which has stages of rotating compressor blades spaced between stage of stationary vanes. As the air passes through the compressor, the pressure of the air increases. The compressed air is then directed into one or more combustors where fuel is injected into the compressed air and the mixture is ignited. The hot combustion gases are then directed from the combustion section to a turbine section. As the hot combustion gases pass through the turbine, the stages of the turbine rotate, which in turn, causes the compressor to rotate.
The air from the inlet is directed through a compressor section, with the compressor having a plurality of alternating axial stages of rotating blades and stationary vanes. As the air travels through the compressor, its pressure increases as well as its temperature. An axial stage of vanes and mounting hardware forms a diaphragm that is secured to the engine and directs the flow of air onto the compressor blades. In prior designs, circular inner diameter and outer diameter rings were used with slots cut through the rings for airfoils to slide through the slots. The airfoils were then welded to the rings to form the vane diaphragms. The full-circle rings and vanes were split into two, 180-degree segments and each of these segments was then assembled into an engine. This assembly has numerous drawbacks including manufacturing and production issues, airfoil cracking at the weld joints during operation, and durability issues regarding seals associated with the diaphragm assembly.
In accordance with the present invention, there is provided a novel configuration for a gas turbine engine compressor diaphragm having a plurality of vane segments fastened together to form a vane pack along with a clam shell-type seal box. The vane pack has a plurality of elastomeric seals located at the interfaces between fastened vane segments. The vane pack also engages a seal box at its inner diameter, the seal box having a forward and aft seal carrier portions coupled together and to the compressor diaphragm.
In an embodiment of the present invention, a vane pack assembly for a gas turbine comprises a plurality of vane assemblies coupled together by a first plurality of fasteners. The vane assemblies have an outer platform with a connecting plate extending from a first side and a recessed portion along the opposite side, an inner platform and one or more airfoils extending therebetween. Each of the connecting plates has a plurality of holes that correspond to a plurality of threaded holes in the recessed portion when a connecting plate is placed over a recessed portion of an adjacent vane assembly. The recessed portion in the outer platform also corresponds generally in dimension and shape to the connecting plate. A plurality of fasteners pass through the plurality of holes in the connecting plate and secure the connecting plate in the recessed portion through the plurality of threaded holes in the recessed portion. The vane pack assembly also includes an elastomeric seal that is located in the recessed portion to provide both sealing and vibration dampening capabilities.
In an alternate embodiment, an improved seal box for engaging a plurality of vane assemblies is provided that does not require modifications to an existing compressor case. The seal box is a region around the inner diameter of a vane pack assembly adjacent to a rotating disk. The seal box provides for increased durability at hook portions, increased damping in conjunction with the vanes, and improved assembly techniques. The seal box comprises a forward seal carrier segment having a first forward radially extending wall connected to a second forward radially extending wall by a first generally axial portion and an aft seal carrier segment having a first aft radially outward extending wall connected to a first aft radially inward extending wall by a second generally axial portion. The seal carrier segments are secured together by a plurality of fasteners passing through the first aft radially inward extending wall and the second forward radially extending wall so as to couple the forward seal carrier and aft seal carrier together and to a vane assembly.
In yet another embodiment of the present invention, an elastomeric seal for use in a compressor diaphragm is also disclosed. The elastomeric seal comprises a first sheet of metal, a silicone sheet, and a second sheet of metal. The silicone sheet is impregnated with fiberglass and is bonded to the first and second sheets of metal to form a reinforced solid bonded seal. The seal is generally used in a joint interface between mating platform portions of vane assemblies, such as between the connecting plate and recessed portions of the outer platform of a vane.
In a further embodiment of the present invention, a method of assembling a compressor diaphragm is disclosed. Adjacent vane assemblies are coupled together at the interface of connecting plates and recessed portions of the outer platforms and at the inner platforms by a plurality of fasteners. The resulting diaphragm assembly is then placed in a forward seal carrier segment and an aft seal carrier segment is then placed onto the diaphragm assembly. The seal carrier segments are then fastened to the diaphragm assembly.
Additional advantages and features of the present invention will be set forth in part in a description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from practice of the invention. The instant invention will now be described with particular reference to the accompanying drawings.
The present invention is described in detail below with reference to the attached drawing figures, wherein:
The subject matter of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different components, combinations of components, steps, or combinations of steps similar to the ones described in this document, in conjunction with other present or future technologies.
Referring initially to
A compressor diaphragm in accordance with an embodiment of the present invention is shown in
To secure the vane assembly 300 to an adjacent vane assembly 330, as depicted in
In order to minimize any gaps between adjacent vane assemblies 300 and 330, the segments are also fastened to each other at the inner vane platform 316, with the fasteners 340 extending in a generally circumferential direction. The fasteners 340 connect adjacent inner platforms 316 through a recessed portion 342 in the inner platform 316 (see
The quantity of airfoils 306 that extend between the platforms 302 and 316 can vary. Vane assemblies 300 can have a single airfoil, two airfoils (doublets), or three airfoils (triplets) extending between the platforms, depending on the engine geometry The embodiment depicted in
Referring to
Referring to
Referring to
Referring to
Referring now to
The inner vane platform 316 is also held radially by the seal box 500 through hooks 522 that extend from the first aft radially outward extending wall 512 and the first forward radially extending wall 504. The hooks 522 extend laterally and engage slots 524 in the forward face 307a and aft face 307b of the inner vane platform 316. To further reduce wearing at the interface between the slots 524 and hooks 522, an anti-fretting coating is applied to the contact surfaces of the hooks 522 and slots 524. One such type of anti-fretting coating is an Aluminum Bronze coating. Applying the wear coating to both surfaces creates a uniform wear surface between the inner vane platform 316 and the hooks 522. To minimize any leakage around these interfaces, the hooks 522 and radially-extending walls 504 and 512 are designed to have a limiting axial fit against the inner platform 316 as well as a limiting radial fit with the flange 344.
In yet another embodiment of the present invention, a method of assembling a compressor diaphragm is disclosed. Referring to
The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments will become apparent to those of ordinary skill in the art to which the present invention pertains without departing from its scope.
From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and within the scope of the claims.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/117,313, filed on Nov. 24, 2008.
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Number | Date | Country | |
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61117313 | Nov 2008 | US |