None.
1. Field of the Invention
The present invention relates generally to a gas turbine engine, and more specifically to a seal between opposing slots that suffer from relative movement.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
In a gas turbine engine, such as a large frame heavy-duty industrial gas turbine (IGT) engine, a hot gas stream generated in a combustor is passed through a turbine to produce mechanical work. The turbine includes one or more rows or stages of stator vanes and rotor blades that react with the hot gas stream in a progressively decreasing temperature. The efficiency of the turbine—and therefore the engine—can be increased by passing a higher temperature gas stream into the turbine. However, the turbine inlet temperature is limited to the material properties of the turbine, especially the first stage vanes and blades, and an amount of cooling capability for these first stage airfoils.
The first stage rotor blade and stator vanes are exposed to the highest gas stream temperatures, with the temperature gradually decreasing as the gas stream passes through the turbine stages. The first and second stage airfoils (blades and vanes) must be cooled by passing cooling air through internal cooling passages and discharging the cooling air through film cooling holes to provide a blanket layer of cooling air to protect the hot metal surface from the hot gas stream.
In order to increase the gas stream temperature, a spar and shell blade and vane design has been proposed. A spar and shell blade or vane includes a separate shell having an airfoil shape that is secured to a spar that functions as a support structure and a cooling air supply channel to the shell. Because the shell is a separate piece, it can be made from a different material such as a refractory material that has a higher melting temperature than the standard nickel super alloys currently used for cast blades and vanes.
In a gas turbine engine, the combustor and the turbine both have surfaces that must include a seal to prevent the hot gas from leaking through. These surfaces include combustor transition ducts, inter-segment gaps for blade outer air seals or duct segments, platform interfaces of turbine vanes, case-tied compressor stator vane segments, and seals between a spar and a shell in a spar and shell stator vane or rotor blade. Because these sealing surfaces are exposed to high temperatures, the opposing slots that receive the seal have a larger relative movement that results in the prior art seals to produce high leakages. The prior art seals are too rigid and not flexible enough in order to maintain a seal surface with the slots due to this high relative movement between the adjacent seal slots.
A flexible seal having an X-shape with four ends that fit with opposed seal slots that have a large amount of displacement. The flexible seal can be used in a high temperature environment such as in a combustor or a turbine of a gas turbine engine to provide for adequate sealing even with displacement of one seal slot in relation to an opposed seal slot.
In one embodiment, the flexible seal is formed from two outwardly curved seal sections bonded together around a middle section that has an X-shape. In other embodiments, a third member is positioned between the two outwardly curved sections and is either free from or bonded to the two curved sections.
The present invention is a flexible or compliant seal that is used in a high temperature environment (such as that in a combustor or a turbine of a gas turbine engine) in which the two opposed seal slots in which the compliant seal is located is not aligned so that prior art rigid seals do not produce adequate sealing. The flexible seal of the present invention will provide a high sealing capability as the opposed two seal slots move with respect to one another. The compliant seal can be used on surfaces such as a combustor transition duct inter-segment gaps for blade outer air seals or duct segments, platform interfaces of turbine vanes, case-tied compressor stator vane segments, and seals between a spar and a shell in a spar and shell stator vane or rotor blade.
The X-shaped compliant seal 15 of the present invention is a spring activated seal that can be used to seal between any two parts that have a groove or slot in each part, such as between turbine vane platforms, blade outer air seal segments, between combustor transition ducts, and between case-tied compressor stator vane segments. This self-activated flexible spring seal 15 has the advantage of being insensitive to profile tolerance and distortion of the mating parts. The flexible spring seal 15 is also resistant to vibratory wear caused by excitation combustor acoustics and from blade passing. The flexible spring seal 15 has less leakage than a single layer seal, because it has two sealing lines of contact in series.
Another benefit to the flexible seal of the present invention is that the two opposed seal slots 14 do not have to have a high tolerance as is required with the rigid seals of the prior art. In the rigid seals of the prior art, the seal slot surfaces would require machining in order to form seal surfaces with low tolerances. In the flexible seal of the present invention, the seal slots can be cast without requiring any machining after casting and still form adequate sealing because of the flexibility of the flexible seal 15.
The shell 11 and the two inserts 12 and 13 have radial extending seal slots 14 formed within in which the radial extending seals 15 are placed. In the embodiment of
In the forward region of the vane, the cooling circuit is a sequential impingement cooling circuit in which a first impingement cooling occurs in the zone 21, and then the cooling air flows to and impinges in the second zone 22, and then is collected and flows to and impinges in the third zone 23 all in series. Because of this series of impingement cooling, the zones must be sealed from one another so that the pressurized cooling air does not flow around the seals. The cooling zones must be separated around the airfoil. An ineffective seal would allow for the cooling air to migrate over and pollute the adjacent zone cooling air flow.
All prior art seals will not work in the spar and shell vane with the sequential impingement cooling inserts of the present invention because the cool spar relative to the hot shell results in relative movement in the axial and radial directions which causes the seals to leak. A small differential pressure between zones eliminates the use of a feather seal.
The various seals of the present invention shown in
The seals are four point seals in which two points on one end make contact with the radial slot in the shell while two points on the other end make contact with the radial slot on the insert. These four points of contact allow for a large amount of relative movement of the slots while still maintaining contact with the slot surfaces to seal the zones. The four point seal is flexible and short to allow for easy installation in the short slot spaces.
The flexible seal 15 in
The two outward curved seal halves are connected together through a brazed or bonded surfaces without any intermediate third piece or through making contact without any braze or bond, or through a third intermediate piece such as those shown in
In testing, the flexible radial seals of the present invention produce a much better seal in the adjacent slots that are displaced from one another than any of the prior art more rigid seals used. The flexible seal 15 of the present invention seals at least four times better than any prior art rigid seal tested.
This invention was made with Government support under contract number DE-FE-0006696 awarded by Department of Energy. The Government has certain rights in the invention.
Number | Name | Date | Kind |
---|---|---|---|
3612551 | Grabill, Jr. | Oct 1971 | A |
4477086 | Feder et al. | Oct 1984 | A |
5265890 | Balsells | Nov 1993 | A |
5865600 | Mori et al. | Feb 1999 | A |
6193240 | Johnson et al. | Feb 2001 | B1 |
6318732 | Hoyes et al. | Nov 2001 | B1 |
6431825 | McLean | Aug 2002 | B1 |
6857849 | Hirst | Feb 2005 | B2 |
7316402 | Paauwe | Jan 2008 | B2 |
7744096 | Kono | Jun 2010 | B2 |
7901186 | Cornett et al. | Mar 2011 | B2 |
20090072497 | Kunitake et al. | Mar 2009 | A1 |
20110020137 | Wilson et al. | Jan 2011 | A1 |
20110079966 | Fleury et al. | Apr 2011 | A1 |
20130028713 | Giri et al. | Jan 2013 | A1 |