Patent Application
20050034461
The present invention relates generally to a combustor dome assembly for a gas turbine engine and, in particular, to a combustor dome assembly including deflector plates which are configured to limit stress imposed thereon. Further, a dome plate for the combustor dome assembly is provided which has a cooling trough in each radial section with purge openings that are substantially aligned with a radial surface of such deflector plates.
It is well known within the combustor art of gas turbine engines that a dome portion, in conjunction with inner and outer liners, serves to form the boundary of a combustion chamber. A mixture of fuel and air is ignited and burned in such combustion chamber so that the products thereof are able to interface with the blades of turbines and produce work through one or more shafts. The annular combustor dome also serves to position a plurality of mixers in a circumferential manner so that a fuel/air mixture is provided to the combustion chamber in a desired manner.
While the typical combustor arrangement has adequate space between swirler cups to incorporate features to enhance the spectacle plate structure (e.g., the addition of ribs, cooling holes and the like), certain geometric restrictions have been introduced by current combustor designs which run lean so as to minimize emissions. As disclosed in U.S. Pat. No. 6,381,964 to Pritchard, Jr. et al., one particular fuel/air mixer configuration includes a fuel nozzle containing a pilot mixer therein. The fuel nozzle is then located within a main mixer. Accordingly, the size of the fuel nozzle and the corresponding swirler assembly associated therewith has increased significantly from those previously utilized and thereby reduced the distance between adjacent swirler cups. Utilization of an annular dome plate having a greater diameter would serve to increase the weight of the engine and require modification of components interfacing therewith. Thus, the openings in the dome plate have been enlarged and thereby lessened the circumferential distance between adjacent openings.
It will be appreciated that a plurality of deflector plates are generally provided in the combustor dome assembly. Such deflector plates are connected to the dome plate adjacent each opening therein in circumferentially spaced relation and protects the dome plate from the extreme effects of the combustion chamber. Cooling for the side edges of the deflector plates is accomplished by means of cooling holes positioned in a radial section of the dome plate between adjacent openings. It has been found, however, that the proximity of adjacent deflector plates and the relatively thin radial sections thereof has created additional stresses which have created deformation and cracking along portions thereof.
Thus, in light of the foregoing, it would be desirable for a combustor dome assembly to be developed which accommodates minimum spacing between adjacent swirler cups. It would also be desirable for a deflector plate to be developed which is configured to limit the stresses imposed thereon. Another desirable feature of the combustor dome assembly is a dome plate which can provide additional purge air to certain regions of the deflector plate while advantageously affecting the temperature and mixture of the fuel and air in the combustion chamber adjacent thereto.
In a first exemplary embodiment of the invention, a combustor dome assembly for a gas turbine engine is disclosed as having a longitudinal centerline axis extending therethrough. The combustor dome assembly includes: an annular dome plate having an inner portion, an outer portion, a forward surface, and a plurality of circumferentially spaced openings formed therein, wherein a radial section defined between each of the openings includes a cooling trough formed therein; an outer cowl connected to the dome plate outer portion at a downstream end thereof; an inner cowl connected to the dome plate inner portion at a downstream end thereof; and, a deflector plate connected to and positioned aft of each opening in the dome plate. Each deflector plate further includes: an annular section at an upstream end thereof having a forward end, an aft end, an inner surface and an outer surface; a substantially planar flange connected to the aft end of the annular section, the planar flange including an outer circumferential surface, an inner circumferential surface, a first radial surface, a second radial surface, and an opening therein sized to the inner surface of the annular section so as to form opposing radial sections; a first flange connected to the outer circumferential surface of the planar flange at a predetermined angle thereto; and, a second flange connected to the inner circumferential surface of the planar flange at a predetermined angle thereto. The first and second radial sections of the deflector plate planar flange are configured so at least a portion of the dome plate cooling trough is in flow communication with a combustion chamber aft of the dome plate.
In a second exemplary embodiment of the invention, a deflector plate for a gas turbine engine combustor is disclosed as having a longitudinal centerline axis therethrough. The deflector plate includes: an annular section at an upstream end thereof having a forward end, an aft end, an inner surface and an outer surface; a substantially planar flange connected to the aft end of the annular section, the planar flange including an outer circumferential surface, an inner circumferential surface, a first radial surface, a second radial surface, and an opening therein sized to the inner surface of the annular section so as to form opposing radial sections; a first flange connected to the outer circumferential surface of the planar flange at a predetermined angle thereto; and, a second flange connected to the inner circumferential surface of the planar flange at a predetermined angle thereto. The first and second radial sections include a notched portion therein so as to reduce stress imposed on the radial sections of the planar flange.
In a third embodiment of the present invention, an annular dome plate for a gas turbine engine combustor is disclosed as having a longitudinal centerline axis therethrough. The dome plate includes an inner portion, an outer portion, and a middle portion located between the inner and outer portions, wherein a plurality of circumferentially spaced openings are formed in the middle portion. The middle portion further includes a radial section defined between each of the openings, as well as a cooling trough formed in each radial section having a plurality of cooling holes formed therein and at least one purge opening of substantially greater size than the cooling holes formed therein.
Referring now to the drawings in detail, wherein identical numerals indicate the same elements throughout the figures,
More specifically, it will be understood that dome plate 20 is annular in configuration and includes an inner portion 30, an outer portion 32, a forward surface 34 and a plurality of circumferentially spaced openings 36 formed therein (see
Deflector plates 28 are associated with each opening 36 in dome plate 20 and therefore are spaced in circumferential manner therearound. Each deflector plate 28 is preferably attached to dome plate 20 by means of brazing or the like. More specifically, deflector plates 28 each include a generally annular section 27 at an upstream end thereof having a forward end 77, an aft end 78, an inner surface 79, and an outer surface 80 (see
Further, a first flange 31 is connected to outer circumferential surface 82 of planar flange 29 at a predetermined angle and a second flange 33 is similarly connected to inner circumferential surface 84 of planar flange 29 at a predetermined angle. First and second angled flanges 31 and 33 are configured so as to extend adjacent to outer and inner dome portions 32 and 30, respectively. A thermal barrier coating is preferably applied to at least a portion of angled flanges 31 and 33, as identified by reference numerals 43 and 51.
In order to limit the stresses imposed upon deflector plates 28, a portion 93 (identified in phantom with respect to radial section 94) has been removed from radial sections 92 and 94 so that notched portions 96 and 98, respectively, are defined. It will be seen that notched portions 96 and 98 are preferably located where radial sections 92 and 94 have a minimum circumferential length identified by reference numeral 100. Notched portions 96 and 98 are also preferably substantially semi-circular in shape so that first and second radial surfaces 86 and 88 include an arcuate portion 102 and 104, respectively. It will be noted that each portion 96 and 98 preferably has a predetermined radial length 106 (approximately 5-25% of radial surfaces 86 and 88) and a predetermined circumferential length 108 (approximately 70-90% of circumferential length 100 for radial sections 37). Accordingly, radial sections 92 and 94 will maintain a minimum circumferential length 110 (approximately 10-30% of circumferential length 100).
It is also preferred that arcuate portions 102 and 104 be configured so as to be nonplanar. As best seen in
With respect to purge openings 23 formed in middle portion 25 of cooling trough 35, it will be appreciated from
In this way, it will be appreciated that cooling air flow from purge openings 23 are aligned with certain hot spots located between adjacent swirler cups. This serves to dilute the fuel/air ratio significantly and reduce the local temperature and formation of NOx at such locations. Moreover, air flowing through purge openings 23 convectively cools arcuate portions 102 and 104 of deflector plate radial surfaces 86 and 88 (where thermal barrier coating is not applied), as well as purges a cavity formed by notched portions 96 and 98 to prevent ingestion of hot combustion products.
It will further be understood from
Fuel nozzle 24 is preferably of the type disclosed in U.S. Pat. No. 6,381,964 to Pritchard, Jr. et al., which is hereby incorporated by reference. It will be appreciated that fuel nozzle 24 is larger than typical fuel nozzles and therefore requires larger openings 36 in dome plate 20. Accordingly, each opening 36 in dome plate 20 has at least a predetermined diameter (approximately at least three times larger than prior dome plate openings), where a circumferential distance 64 between openings 36 (i.e., that of radial sections 37) is no greater than a predetermined amount (approximately one-third or less than that in prior dome plates).
Each swirler 26 is located between forward surface 34 of dome plate 20 and upstream ends 47 and 49 of outer and inner cowls 38 and 44, respectively, so as to be in substantial alignment with an opening 36 in dome plate 20. Further, each swirler 26 includes a forward portion 50 and an aft portion 52. It will be appreciated that swirlers 26 are not fixed or attached to any other component of air/fuel mixer 22, but are permitted to float freely in both a radial and axial direction with respect to a centerline axis 53 through each opening 36. Each swirler 26 preferably includes vanes 48 therein which are oriented to provide swirl in a substantially radial direction with respect to centerline axis 53.
It will be seen that swirler forward portion 50 preferably includes a radial flange 70 which moves between first and second tab members 54 and 56 associated with outer and inner cowls 38 and 44, respectively, as disclosed in a patent application entitled “Combustor Dome Assembly Of A Gas Turbine Engine Having A Free Floating Swirler.” Such patent application, having Serial No. 10/___,___, is filed concurrently herewith, is also owned by the assignee of the present invention, and is hereby incorporated by reference. Swirler forward portion also includes an axial section 72 for receiving fuel nozzle 24. Anti-rotation members (not shown) are provided on a forward surface of axial section 72 to engage with those of adjacent swirlers and thereby prevent swirlers 26 from spinning.
Swirler aft portion 52 preferably includes a flange 74 which is able to slide radially along a boss section 75 of dome plate forward surface 34. A lip 76 is connected to flange 74 and is preferably oriented substantially perpendicular to flange 74 so that it is substantially parallel to centerline axis 53. It will be noted that lip 76 extends aft of dome plate forward surface 34 so that it interfaces with annular section 27 of deflector plate 28 and thereby limits radial movement of swirler 26. Flange 74 of swirler aft portion 52 is preferably contoured as described in a patent application entitled “Combustor Dome Assembly Having A Contoured Swirler,” which is filed concurrently herewith. Such patent application, having Serial No. 10/___,___, is also owned by the assignee of the present invention and is hereby incorporated herein by reference.
Having shown and described the preferred embodiment of the present invention, further adaptations of the combustor dome assembly, as well as the deflector plates and the dome plate thereof can be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the invention.
