Patent Application
20150040568
The application relates generally to gas turbine engines, and more particularly, to combustor floating collar assemblies for such engines.
Gas turbine combustors are typically provided with floating collar or seal assemblies for mounting igniters or fuel nozzles to the combustor, in order to facilitate relative movement of igniters or fuel nozzles with controlled leakage therebetween during engine operation. This arrangement helps to avoid loading on the igniter or fuel nozzles from the combustor movement. Conventional combustor floating collar assemblies are provided with anti-rotation tabs or brackets to prevent the igniters or fuel nozzles from rotation, while permitting axial and radial/lateral movement with respect to the combustor. Fretting wear of the anti-rotation tabs or brackets occurs in conventional floating collar assemblies due to aerodynamic loading and vibration. This can result in pre-mature removal of engines in the field due to difficulties reinstalling igniters or fuel nozzles during overhaul. A floating collar with worn-out anti-rotation tabs may start rotating and creating grooves in the igniter or fuel nozzle which is secured by the floating collar. Accordingly there is a need to provide a solution which addresses these and other limitations of the conventional floating collar assemblies.
In one aspect, there is provided a gas turbine combustor including a floating collar assembly, the floating collar assembly comprising: a hollow boss, a passage extending through the boss along an axis between first and second opposed ends of the boss, the first end of the boss affixed to a wall of the gas turbine combustor and the passage communicating with an interior of the combustor, the passage having a portion at the second end with a cross-section normal to the axis which is non-axisymmetric relative to the axis; a floating collar disposed at least partially within the passage, the floating collar having an non-axisymmetric outer periphery selected to be complementary to and received in the non-axisymmetric portion of the passages to anti-rotate the floating collar with respect to the boss relative to the axis, the outer periphery defining a cross-section normal to the axis fully confined within the portion of the passage; and a retainer apparatus axially restraining the floating collar at least partially within the passage.
In another aspect, there is provided a floating collar assembly for a gas turbine combustor comprising: a boss having a central axis and opposed first and second ends, a passage extending through the boss in an axial direction from the first to second end, a boss flange extending outwardly from the second end, a non-axisymmetric peripheral wall extending along an entire outer periphery of the boss flange and projecting axially from the boss flange in a direction away from the first end to form a recess communicating with the passage of the boss, the peripheral wall forming a closed inner peripheral surface; a floating collar having an outer periphery disposed within and laterally surrounded by the peripheral wall and defining a central aperture, the outer periphery including a non-axisymmetric surface mated with the inner peripheral surface of the non-axisymmetric peripheral wall to provide anti-rotation of the floating collar with respect to the boss and the axis; and a cap defining a central aperture axially extending therethrough, the cap being attached to the peripheral wall, the floating collar being restrained within the recess by the peripheral wall and the cap.
Reference is now made to the accompanying figures in which:
It will be noted that throughout the appended drawing, like features will be identified by like reference numerals.
Referring to
It should be noted that the apparatus 32 is applicable to both igniters and fuel nozzles and therefore, the igniter 30 described hereinafter may be replaced by the fuel nozzle 28.
In accordance with one embodiment, the hollow boss member 38 may define a central axis 44 and may have opposed ends 46, 48. A passage 50 may extend along its axis through the boss member 38 in the direction of the central axis 44 between the ends 46, 48. The passage 50 may have an enlarged portion to form a recess 52 with an inner periphery 54 which defines a closed surface in a non-axisymmetric shape with respect to the central axis 44.
It should be noted that throughout this description, the axial and radial directions are defined respectively with respect to the central axis 44.
In particular, the hollow boss member 38 may include a cylindrical body 56 defining a major section of the passage 50 extending therethrough. One end of the cylindrical body 56 forms the end 46 of the hollow boss member 38 and is affixed, for example by welding to the combustor wall 36, with the passage 50 substantially aligned with the opening 34. At the other end (not numbered) of the cylindrical body 56, a flange 58 extends from the cylindrical body 56 radially and outwardly with respect to the central axis 44. A peripheral wall 60 extends along an entire outer periphery of the flange 58 and projects axially from the flange 58 to thereby form the recess 52 defined within the inner periphery 54. The peripheral wall 60 which also forms the closed surface to define the inner periphery 54 which includes at least one section formed with a flat surface in this example. The peripheral wall 60 or the inner periphery 54 may define, for example a square shape (as shown in
Optionally, a positioning ring 62 may be provided on the hollow boss member 38, projecting radially outwardly from the cylindrical body 56 to thereby define an annular positioning shoulder 64 between the cylindrical body 56 and the positioning ring 64 at the end 46 of the cylindrical body 56 (also the end of the hollow boss member). The annular positioning shoulder 64 allows the positioning ring 62 to rest on the edge of the opening 34 of the combustor wall 36 while allowing the end 46 of cylindrical body 56 to extend into the opening 34 of the combustor wall 36 for secure attachment of the hollow boss member 38 to the combustor wall 36.
The floating collar 40 has an outer periphery 66 with a non-axisymmetric shape complementary to and being contained within the inner periphery 54 of the recess 52 so that the floating collar is somewhat shielded or protected by the boss to reduce aerodynamic loads caused by air flowing around the combustor. The cap 42 may also provide further shielding or protection to reduce damage from these aerodynamic loads.
In order to allow a body of the igniter 30 to extend through the passage 50 of the hollow boss member 38 into the combustor 28, or to be exposed to a chamber of the combustor 28, when the floating collar 40 snugly surrounds the body of the igniter 30. The outer periphery 66 of the floating collar 40 may include at least one section formed with a flat surface corresponding with and to be mated with the flat surface of the at least one section of the inner periphery 54 of the recess 52 of the hollow boss member 38, thereby preventing substantial rotation of the floating collar 40 with respect to the hollow boss member 38.
In accordance with an embodiment, the floating collar 40 may include a cylindrical body 70 extending radially with respect to the central axis 44 and may define a central aperture 68 which snugly receives the body of the igniter 30. A flange 72 may extend radially outwardly from the cylindrical body 70. The flange 72 may be positioned substantially normal to the central axis 44 and a periphery of the flange 72 may define the outer periphery 66 of the floating collar 38. The outer periphery 66 may be completely surrounded by the peripheral wall 60 of the hollow boss member 38 and at least one section of the outer periphery 66 which is formed with a flat surface, may correspond with and mate with the flat inner surface of the at least one section of the peripheral wall 60 of the hollow boss member 38.
The outer periphery 66 of the floating collar 40 may define a square shape (as shown in
The flange 72 of the floating collar 40 may be positioned at one end of the cylindrical body 70 and the other end of the cylindrical body 70 may have a bevelled annular inner surface (not numbered) such that the central aperture 68 formed by the cylindrical body 70 of the floating collar 40 may have an enlarged diameter at the other end of the cylindrical body 70 in order to reduce the annular contact area between the body of the igniter 30 and the floating collar 40 when the body of the igniter 30 is snugly received in the central aperture 68 of the floating collar 40.
In accordance with one embodiment, the cap 42 which may be formed by a flat plate, defines a central aperture 74 axially extending therethrough. The cap 42 may be positioned on the peripheral wall 60 which forms the end 48 of the hollow boss member 38, in order to cover the recess 52, such that at least a portion of the floating collar 40 is restrained within the recess 52 by the peripheral wall 60 and the cap 42 with axial and radial tolerances, thereby providing a “floating” function of the floating collar 40 with respect to the hollow boss member (as shown in
As illustrated in
It should be noted that the tolerances illustrated in
The cap 42 may have a shape similar to the shape of the outer peripheral wall 60 of the hollow boss member 38 such as a square or triangle. Nevertheless, the cap 42 may have an outer periphery defining a shape different from the shape defined by the outer peripheral wall 60 of the hollow boss member 38.
In accordance with another possible embodiment, the apparatus may further include a mounting plate 43. The mounting plate 43 may be larger than the cap 42 such that the mounting plate 43 can be positioned on the cap 42 and removably secured to the combustor wall 36 by, for example bolts/screws (not shown). The mounting plate 43 may define an aperture (not numbered) allowing the body of the igniter 30 to extend therethrough while applying mounting forces on the cap 42 which in turn encloses the flange 66 of the floating collar 40 within the recess 52 of the hollow boss member 38.
It will be understood that the cap 42 and the portion of passage with a reduced cross-section relative to the recess co-operate to axially restrain the floating collar in the boss, and thus together provide a retainer apparatus. The cap 42 may be replaced by any suitable device which axially restrains the floating collar outwardly, for example such as a suitable clip (not shown) or other means. Similarly, the change in cross-section in the passage may be replaced by other means to axially restrain the floating collar inwardly, such as a local reduction in cross-section (e.g. a ridge or bump, not shown) or a suitable clip (not shown) or other means.
The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the described subject matter. For example, the inner periphery of the recess of the hollow boss member and the outer periphery of the floating collar may have shapes other than those described in the above-described embodiments. For example, the hollow boss member may have a recess with an inner periphery defining any suitable non-axisymmetric shape. Many options are possible which suitably anti-rotate of the floating collar about the axis with respect to the hollow boss member, such as nut-like hexagonal or other flats, ellipses, to name only a few. Modifications which fall within the scope of the described subject matter will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.
