The present invention relates to a vane for directing hot gases in a gas turbine engine.
With reference to
The gas turbine engine 10 works in a conventional manner so that air entering the intake 11 is accelerated by the fan 12 to produce two air flows: a first air flow A into the intermediate pressure compressor 14 and a second air flow B which passes through the bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 13 compresses the air flow A directed into it before delivering that air to the high pressure compressor 14 where further compression takes place.
The compressed air exhausted from the high-pressure compressor 14 is directed into the combustion equipment 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 16, 17, 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low-pressure turbines respectively drive the high and intermediate pressure compressors 14, 13 and the fan 12 by suitable interconnecting shafts.
A row of static nozzle guide vanes (NGVs) mounted into the turbine casing is provided at the entrance to each of the high, intermediate and low-pressure turbines 16, 17, 18. The NGVs are shaped to swirl the gasflow in the direction of rotation of the following rotor blades, and thereby to convert part of the gasflow's heat and pressure energy into kinetic energy from which the rotor blades can generate power. The NGVs of particularly the high and intermediate-pressure turbines 16, 17 tend to be cooled in order to withstand the high temperatures to which they are exposed.
Impingement cooling is typically used to cool intermediate-pressure NGVs. A conventional impingement tube 26 is inserted into the hollow NGV, as shown in
An impingement cooling scheme of this type can provide effective cooling, while also leaving the internal space of the impingement tube 26 free to carry e.g. support struts for supporting engine bearing structures, and engine oil and air feeds.
NGV aerofoil shapes are becoming, however, increasingly complex. For example,
An aim of the present invention is to provide a vane including an impingement tube which can inserted into the vane even when the vane has a re-entrant internal cavity feature.
Accordingly, a first aspect of the present invention provides a vane for directing hot gases in a gas turbine engine, the vane including:
a hollow aerofoil portion, which in use spans the working gas annulus of the engine, and
an impingement tube which forms a covering over the interior surface of the aerofoil portion and which has jet-forming apertures formed therein for the production of impingement cooling jets;
wherein the impingement tube includes two tube portions which are separately insertable into position into the aerofoil portion to form the covering, and
an expansion member which, when the tube portions are in position in the aerofoil portion, is locatable in the aerofoil portion to urge each tube portion outwardly and thereby holds the tube portions in position against the aerofoil portion.
Advantageously, by dividing the impingement tube into separate tube portions, each tube portion be configured such that it is possible to be positioned in the cavity of the aerofoil portion, even when that cavity has a re-entrant feature. The expansion member then holds the tube portions in position.
The vane may have any one or, to the extent that they are compatible, any combination of the following optional features.
Typically, one of the tube portions is positioned forward in the aerofoil portion and the other tube portion is positioned rearward in the aerofoil portion. For example the forward portion can wrap around the inside of the leading edge of the aerofoil portion, and the rearward portion can wrap around the inside of the trailing edge.
Either or both of the tube portions may be resiliently deformable to facilitate its insertion into the aerofoil portion. For example, the or each tube portions can be pinched inwardly to reduce its width on insertion into the aerofoil portion, and then allowed to resile outwardly to regain its shape after insertion.
Typically, the expansion member urges the tube portions outwardly against the pressure surface side and the suction surface side of the aerofoil portion. The aerofoil portion typically has a plurality of projections and/or ridges on the internal surface against which the tube portions are held, the projections and/or ridges setting up a space between the impingement tube and the aerofoil portion through which the air from the cooling jets can flow.
The outward urging can be achieved in various ways. One option is for expansion member to be slidably insertable into the aerofoil portion to urge the positioned tube portions outwardly with a wedging action. Another option is for expansion member to be rotatably connected to one of the tube portions to urge the positioned tube portions outwardly with a camming action.
Preferably the expansion member and the tube portions have complimentary engaging formations which retain the expansion member in its location to urge the tube portions outwardly. In this way, inadvertent loss of the expansion member from the aerofoil portion, and hence loosening of the tube portions can be avoided.
Preferably, the expansion member is removably locatable in the aerofoil portion. This allows the tube portions also to be removably positionable so that they can be replaced if necessary.
The tube portions may have seal formations at which the tube portions sealingly join to each other. Such formations help to prevent cooling air leaking through the joins between the tube portions and by-passing the jet-forming apertures. The expansion member can conveniently urge the tube portions outwardly at the seal formations. In this way, outward pressure from the expansion member can help to perfect the seals made by the seal formations.
The expansion member may be a bimetallic strip. This can help the member to expand and contract with expansion and contraction of the aerofoil portion, maintaining the outward urging on the tube portions.
The expansion member may be a compression spring which presses on the tube portions to urge them outwardly.
Typically there are only two tube portions. This allows the outward expansion of the tube portions to be performed by only one expansion member, helping to maintain the amount of available space inside the impingement tube for e.g. engine support structures and fluid feeds. However, it is possible for the impingement tube to include more than two tube portions which are separately insertable into position in the aerofoil portion to form the covering, and a plurality of expansion members which, when the tube portions are in position in the aerofoil portion, are locatable in the aerofoil portion to urge each tube portion outwardly and thereby holds the tube portions in position against the aerofoil portion.
Typically, the vane is a nozzle guide vane, e.g. an intermediate turbine nozzle guide vane.
Typically, the vane has a re-entrant internal cavity feature which would prevent a one-piece impingement tube from being inserted therein.
A second aspect of the present invention provides an impingement tube suitable for use in the vane of any one of the first aspect.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:
a) and 11(b) show schematically the rearward part of an aerofoil section of the aerofoil portion and another possible form for the expansion member (a) after insertion and (b) after subsequent deformation so that the member acts as a compression spring; and
Next, as shown in
Subsequently, as shown in
a) and (b) shows schematically a possible form for the expansion member 43a,
a) and (b) shows schematically the rearward part of an aerofoil section of the aerofoil portion 40 and another possible form for the expansion member 43c. The member, when initially located between the sealing strips 44 has a C-shaped cross-section, as shown in
While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
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1103317.2 | Feb 2011 | GB | national |
Number | Name | Date | Kind |
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4437810 | Pearce | Mar 1984 | A |
6450759 | Miller et al. | Sep 2002 | B1 |
20060120869 | Wilson et al. | Jun 2006 | A1 |
Number | Date | Country |
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1 674 660 | Jun 2006 | EP |
2 350 867 | Dec 2000 | GB |
2 386 926 | Oct 2003 | GB |
Entry |
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Jun. 2, 2011 Search Report issued in British Patent Application No. 1103317.2. |
Number | Date | Country | |
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20120219402 A1 | Aug 2012 | US |