COMBUSTION CHAMBER ASSEMBLY WITH SPECIFICALLY ARRANGED MIXING AIR HOLES ON INNER AND OUTER COMBUSTION CHAMBER WALL

Abstract

A combustion chamber for an engine includes inner and outer combustion chamber walls bounding a combustion space. Three mixing air holes with respective central points at corner points of a virtual first or second triangle are arranged on mutually opposite first and second wall segments of the inner and outer walls. The second triangle of the second wall segment of the outer wall is oriented rotated by 180° with respect to the first triangle of the first wall segment of the inner wall, and the mixing air holes arranged in rows on the first and second wall segments are arranged with respect to one another so the mixing air holes of the first and second wall segments that are arranged at the corner points of the first and second triangles do not lie opposite a mixing air hole of the second or first wall segment.

Claims

1. A combustion chamber assembly, having a combustion chamber for an engine, which comprises inner and outer combustion chamber walls for bounding a combustion space of the combustion chamber, wherein the combustion chamber extends along a central axis in an axial direction from a first axial end to a second axial end, at least two rows of mixing air holes following one another in the axial direction are provided both on the inner combustion chamber wall and on the outer combustion chamber wall, said mixing air holes being provided for conducting mixing air into the combustion space, in each case a plurality of mixing air holes are arranged one behind another in a row of mixing air holes along a circumferential direction about the central axis, both the inner combustion chamber wall and the outer combustion chamber wall are divided in the circumferential direction in each case into wall segments on which the mixing air holes are in each case arranged in a predefined pattern, wherein three mixing air holes of two rows following one another in the axial direction are arranged with their respective central points at corner points of a virtual first triangle on a first wall segment of the inner combustion chamber wall, three mixing air holes of two rows following one another in the axial direction are arranged with their respective central points at corner points of a virtual second triangle on a second wall segment of the outer combustion chamber wall, and the second triangle is oriented rotated by 180° with respect to the first triangle and the mixing air holes in the rows on the first and second wall segments are arranged with respect to one another in such a manner that the mixing air holes of the first and second wall segments that are arranged at the corner points of the first and second triangles in each case do not lie opposite a mixing air hole of the second or first wall segment.

2. The combustion chamber assembly according to claim 1, wherein the first triangle and the second triangle are both isosceles triangles.

3. The combustion chamber assembly according to claim 2, wherein the tip of the first isosceles triangle and the tip of the second isosceles triangle, in a top view along a viewing direction running perpendicularly to the axial direction and perpendicularly to the circumferential direction, lie on an axis of symmetry, with respect to which, in the top view, a first pattern of the mixing air holes on the first wall segment is symmetrical, and with respect to which, in the top view, a second pattern of the mixing air holes on the second wall segment is symmetrical.

4. The combustion chamber assembly according to claim 3, wherein the axis of symmetry runs parallel to a nozzle axis along which a nozzle head of a fuel nozzle which is provided for injecting fuel into the combustion chamber and belongs to the combustion chamber assembly extends.

5. The combustion chamber assembly according to claim 2, wherein the first isosceles triangle and the second isosceles triangle are identical.

6. The combustion chamber assembly according to claim 1, wherein at least one further mixing air hole is provided on the first wall segment in at least one row in which a mixing air hole is provided, the central point of which lies at a corner point of the first triangle.

7. The combustion chamber assembly according to claim 1, wherein at least one further mixing air hole is provided on the second wall segment in at least one row in which a mixing air hole is provided, the central point of which lies at a corner point of the second triangle.

8. The combustion chamber assembly according to claim 6, wherein a distance measured in the circumferential direction between the one mixing air hole and the at least one further mixing air hole is greater than a distance of the at least one further mixing air hole from a mixing air hole, which follows in the circumferential direction, of a wall segment which is adjacent in the circumferential direction.

9. The combustion chamber assembly according to claim 8, wherein the distance measured in the circumferential direction between the one mixing air hole and the at least one further mixing air hole is twice as large as the distance of the at least one further mixing air hole from the mixing air hole, which follows in the circumferential direction, of the wall segment which is adjacent in the circumferential direction.

10. The combustion chamber assembly according to claim 2, wherein the distance between the one mixing air hole and the further mixing air hole which does not lie at a corner point of the first isosceles triangle and belongs to the row on the first wall segment corresponds to the length of the base of the first isosceles triangle.

11. The combustion chamber assembly according to claim 2, wherein the distance between the one mixing air hole and the further mixing air hole which does not lie at a corner point of the second isosceles triangle and belongs to the row on the second wall segment corresponds to the length of the base of the second isosceles triangle.

12. The combustion chamber assembly according to claim 1, wherein a total of precisely five mixing air holes are provided in the first two rows following one another in the axial direction per wall segment.

13. The combustion chamber assembly according to claim 1, wherein an axial distance between two rows of mixing air holes lies in a range of 0.05 d to 0.4 d, where d is a distance between the first and second wall segments.

14. The gas turbine engine having at least one combustion chamber assembly according to claim 1.

Description

[0022] In the figures:

[0023] FIG. 1 shows a segment, in a perspective view, of part of an embodiment variant of a proposed combustion chamber assembly with specific mixing air hole arrangements on inner and outer combustion chamber walls downstream of a nozzle head of a fuel nozzle;

[0024] FIG. 2 shows the mixing air hole arrangement on the inner and outer combustion chamber walls of the combustion chamber assembly of FIG. 1 in a top view;

[0025] FIG. 3 shows part of the combustion chamber assembly of FIGS. 1 and 2 in a cross section;

[0026] FIG. 4A shows a schematic sectional illustration of a gas turbine engine, in which a proposed combustion chamber assembly is used;

[0027] FIG. 4B shows a schematic sectional illustration of a combustion chamber of the gas turbine engine of FIG. 4A;

[0028] FIG. 4C shows a segment of an enlarged sectional illustration of a combustion chamber with a combustion chamber shingle.

[0029] FIG. 4A illustrates, schematically and in a sectional illustration, a (turbofan) engine T in which the individual engine components are arranged one behind another along an axis of rotation or central axis M, and the engine T is formed as a turbofan engine. At an inlet or intake E of the engine T, air is drawn in along an inlet direction by means of a fan F. This fan F, which is arranged in a fan casing FC, is driven by means of a rotor shaft S which is set in rotation by a turbine TT of the engine T. Here, the turbine TT adjoins a compressor V, which comprises, for example a low-pressure compressor 111 and a high-pressure compressor 112, and possibly also a medium-pressure compressor. On the one hand, the fan F conducts air in a primary air flow F1 to the compressor V, and, on the other hand, to generate thrust, in a secondary air flow F2 to a secondary flow duct or bypass duct B. The bypass duct B here runs around a core engine comprising the compressor V and the turbine TT and comprising a primary flow duct for the air supply to the core engine by the fan F.

[0030] The air conveyed into the primary flow duct by means of the compressor V passes into a combustion chamber BK of the core engine, in which the drive energy for driving the turbine TT is generated. For this purpose, the turbine TT has a high-pressure turbine 113, a medium-pressure turbine 114 and a low-pressure turbine 115. Here, the energy released during the combustion is used by the turbine TT to drive the rotor shaft S and thus the fan F in order to generate the required thrust by means of the air conveyed into the bypass duct B. Both the air from the bypass duct B and the exhaust gases from the primary flow duct of the core engine flow out via an outlet A at the end of the engine T. In this arrangement, the outlet A generally has a thrust nozzle with a centrally arranged outlet cone C.

[0031] FIG. 4B shows a longitudinal section through the combustion chamber BK of the engine T. The combustion chamber BK is designed here as an annular combustion chamber which forms part of an embodiment variant of a proposed combustion chamber assembly. A nozzle assembly is provided for the injection of fuel or an air-fuel mixture into a combustion space 30 of the combustion chamber BK. Said nozzle assembly comprises a combustion chamber ring, on which multiple fuel nozzles 2 are arranged along a circular line around the central axis M. Here, on the combustion chamber ring, there are provided the nozzle outlet openings of the respective fuel nozzles 2 which are situated within the combustion chamber BK. Here, each fuel nozzle 2 comprises a flange by means of which a fuel nozzle 2 is screwed to an outer casing 22.

[0032] A configuration of the combustion chamber BK is illustrated specifically in the enlarged sectional illustration of FIG. 4C. The combustion chamber BK here comprises the fuel nozzle 2 which is held in a combustion chamber head. The fuel nozzle 2 is used to inject fuel into the combustion space 30 of the combustion chamber BK. The exhaust gases of the mixture ignited within the combustion space 30 pass in an axial direction x via a turbine inlet guide vane row 33 to the high-pressure turbine 113 in order to set the turbine stages into rotation. The combustion chamber BK therefore extends in the axial direction x from a first axial end with a combustion chamber head to a second axial end at which the exhaust gases arising in the combustion space 30 during the combustion are conducted to the high-pressure turbine 113 in order to generate thrust.

[0033] The combustion space 30 is bounded by, with respect to the central axis M of the engine T, radially inner and radially outer combustion chamber walls 32a, 32b of a combustion chamber housing of the combustion chamber BK, said combustion chamber walls each extending, on the one hand, along the axial direction x and, on the other hand, along a circumferential direction U (cf. FIGS. 1 and 2) about said axial direction x. The combustion chamber walls 32a and 32b therefore extend, on the one hand, along the axial direction x along the central axis M and along the circumferential direction U. A radial direction r runs perpendicularly both to the axial direction x and to the circumferential direction. Along said radial direction r, air flows, for example, via mixing air holes 35 into the combustion space 3.

[0034] Combustion chamber shingles 34a, 34b are arranged on the inner side of the combustion chamber walls 32a, 32b. The combustion chamber walls 32a, 32b therefore surround the combustion space 30 of the combustion chamber BK and bear the combustion chamber shingles 34a, 34b, with which the combustion chamber walls 32a, 32b are lined in order to permit additional cooling and to withstand the high temperatures prevailing in the combustion space 30.

[0035] The combustion chamber shingles 34a, 34b are each held here on the respective inner or outer combustion chamber wall 32a, 32b via one or more bolts 4. Each bolt 4 reaches here through an opening on the combustion chamber wall 32a or 32b and is fixed to the combustion chamber wall 32a or 32b via a respective nut 5. For example, a plurality of effusion cooling holes provided on a combustion chamber shingle 34a or 34b make it possible to cool the respective combustion chamber shingle 34a or 34b. In addition, a combustion chamber shingle 34a, 34b can have at least one admixing hole via which air can flow into the combustion space 30 from a surrounding exterior space. The air flowing via an admixing hole is used here for cooling and/or leaning of the combustion.

[0036] The exterior space surrounding the combustion chamber BK, for example in the form of an annular duct, forms an air supply 36 for the mixing air holes 35 (and possible effusion cooling holes). Air flowing into the combustion chamber BK along an inflow direction Z is divided here at the first axial end in the region of the fuel nozzle 2 via a section configured in the manner of a hood into a primary air flow for the combustion space 30 and a secondary air flow for the surrounding exterior space with the air supply 36. The air conventionally flows here into the combustion chamber BK via a diffusor (not illustrated).

[0037] FIGS. 1, 2 and 3 show, with a greater degree of detail, embodiment variants of the proposed solution, for illustrating special arrangements for the mixing air holes 35 on the inner and outer combustion chamber walls 32a and 32b. The mixing air holes are denoted here by 6.1a-6.3a, 7.1a-7.2a and 6.1b-6.2b, 7.1b-7.3b and are provided in certain patterns repeating segment by segment in the circumferential direction U on the inner and outer combustion chamber walls 32a and 32b. The positions of the mixing air holes 6.1a-6.3a, 7.1a-7.2a and 6.1b-6.2b, 7.1b-7.3b are furthermore coordinated with one another such that, in particular in the case of a combustion space 30 with a comparatively large pitch-height ratio, a particularly advantageous mixing air flow downstream of a fuel nozzle 2 is produced.

[0038] FIG. 1 perspectively shows a segment of the combustion space 30 looking at the front axial face end together with a segment of an annular heat shield, at the opening of which a nozzle head 2A of the fuel nozzle 2 projects into the combustion space 30 in order to inject fuel into the combustion space 30. The height of the combustion space 30 is defined by a distance d between the opposite combustion chamber walls 32a and 32b at the first axial end in the region of the nozzle head 2A, the distance corresponding to the height of the heat shield segment. The pitch of the combustion space is defined in turn by a width p which measures the heat shield segment carrying the nozzle head 2A and therefore also a respective segment of the inner and outer combustion chamber wall 32a, 32b in the circumferential direction U.

[0039] The inner combustion chamber wall 32a and the outer combustion chamber wall 32b can be divided in the present case (virtually) into individual wall segments which follow one another in the circumferential direction U and on which respectively recurring patterns for the mixing air holes provided on said wall segments are predefined. In the present case, five mixing air holes 6.1a-6.3a, 7.1a-7.2a or 6.1b-6.2b, 7.1b-7.3b are in each case provided per wall segment. The mixing air holes on a respective wall segment are provided symmetrically with respect to an axis of symmetry ML on the respective wall segment. This axis of symmetry ML runs parallel to a nozzle axis DL along which the nozzle head 2A of the fuel nozzle 2 extends and which therefore corresponds to the main direction of flow of fuel from the nozzle head 2A in the direction of the combustion space outlet.

[0040] A mixing air hole arrangement La or Lb for the respective five mixing air holes 6.1a-6.3a, 7.1a-7.2a or 6.1b-6.2b, 7.1b-7.3b is provided on each wall segment of the inner or outer combustion chamber wall 32a, 32b. Each mixing air hole arrangement La, Lb has precisely two rows 6a, 7a or 6b, 7b of mixing air holes. The five mixing air holes 6.1b-6.2b, 7.1b-7.3b of the outer combustion chamber wall 32b are each arranged segment by segment inversely with respect to the mixing air holes 6.1a-6.3a, 7.1a-7.2a of the inner combustion chamber wall 32a. In particular, three mixing air holes 6.2a, 7.1a and 7.2a are arranged with their central points at corner points of a virtual first isosceles triangle LDa on a wall segment of the inner combustion chamber wall 32a, with the tip of said first isosceles triangle LDa and therefore the central point of the mixing air hole 6.2a of the front row 6a lying on the axis of symmetry ML.

[0041] A second isosceles triangle LDb, at the corner points of which the central points of the three mixing air holes 6.1b, 6.2b and 7.2b are located, is provided on the opposite wall segment of the outer combustion chamber wall 32b in a manner rotated by 180° with respect to the first isosceles triangle LDa. Said three mixing air holes 6.1b, 6.2b and 7.2b of the wall segment of the outer combustion chamber wall 32b and the three mixing air holes 6.2a, 7.1a and 7.2a of the wall segment of the inner combustion chamber wall 32a are positioned inversely such that a mixing air hole of the inner combustion chamber wall 32a is not faced by any mixing air hole of the opposite outer combustion chamber wall 32b. Six mixing air flows which are spatially offset from one another are therefore produced downstream of the nozzle head 2A. The production of locally separated mixing air flows in a comparatively compact space downstream of the nozzle head 2A via the groups of mixing air holes 6.2a, 7.1a, 7.2a and 6.1b, 6.2b 7.2b has proven particularly advantageous for efficient thorough mixing of fuel and mixing air in a combustion space 30 having a comparatively large pitch-height ratio p/d.

[0042] FIG. 2 here clarifies the mixing air hole arrangements La, Lb across a plurality of wall segments of the inner and outer combustion chamber walls 32a, 32b. FIG. 2 shows a top view with a viewing direction perpendicular to the circumferential direction U and perpendicular to the main direction of flow s, and therefore perpendicular to the axial direction x.

[0043] FIG. 2 illustrates segments of three wall segments 321b, 320b and 322b, lying next to one another, of the outer combustion chamber wall 32b and the associated opposite wall segments 321a, 320a, 322a of the inner combustion chamber wall 32a. Wall segments of a combustion chamber wall 32a, 32b are separated in pairs from one another by (virtual) segment boundary lines SL. The mixing air arrangements La or Lb of the wall segments 321b, 320b, 322b and 321a, 320a and 322a are in each case axially symmetrical to the axis of symmetry L on a wall segment 320a/b, 321a/b or 322a/b. Furthermore, a mixing air arrangement La or Lb of a wall segment is in each case inverse to an opposite wall segment of the other combustion chamber wall 32a, 32b.

[0044] In the top view of FIG. 2, a first mixing air hole 6.2a of the front row 6a of a first wall segment 320a (of the inner combustion chamber wall 32a) and a first mixing air hole 7.2b of the rear row 7b of a second wall segment 320b (of the outer combustion chamber wall 32b) are provided one behind another along the axis of symmetry ML. Said first mixing air holes 6.2a and 7.2b are therefore arranged axially offset only in the axial direction x and therefore in the main direction of flow s of the fuel injected via the nozzle head 2A. These two first mixing air holes 6.2a and 7.2b are arranged here at a tip of the respective virtual isosceles triangle LDa or LDb, the tips predefining the spatial arrangement of the central three mixing air holes (of a total of five mixing air holes) on a respective wall segment 320a or 320b. Accordingly, two mixing air holes 7.1a and 7.2a are provided in the rear row 7a on the wall segment 320a of the inner combustion chamber wall 32a, the central points of which mixing air holes lie at the other corner points of the first virtual triangle LDa and which are therefore spaced apart from one another at a distance a1 which corresponds to the length of the base of the virtual first triangle LDa. Inversely thereto, mixing air holes 6.1b and 6.2b which lie with their central points at the corner points of the other, second virtual triangle LDb are provided on the front row 6b of the wall segment 320b of the outer combustion chamber wall 32b. Said central points are provided at a distance b1 from one another that corresponds to the length of the base of the virtual second triangle LDb (where here a1=b1).

[0045] In a respective front or rear row 6a or 7b of the two rows of mixing air holes following one another in the axial direction x, by way of which row one mixing air hole 6.2a or 7.2b lying on the axis of symmetry ML is provided on the respective wall segment 320a or 320b, the two further mixing air holes 6.1a, 6.3a or 7.1b, 7.3b are in each case arranged in the circumferential direction U. By contrast, the respective other row 7a or 6b continues to have the two mixing air holes, the centre points of which lie at the corner points of the respective virtual triangle LDa, LDb.

[0046] The additional (fourth and fifth) mixing air holes 6.1a, 6.3a of the front row 6a on the wall segment 320a, or the additional (fourth and fifth) mixing air holes 7.1b, 7.3b of the rear row 7b on the wall segment 320b are in each case provided at a distance from the respective central mixing air hole 6.2a or 7.3b of the respective row 6a or 7b, which distance likewise corresponds to the length of the base of the respective virtual triangle LDa or LDb.

[0047] A row 6a or 7b with three mixing air holes 6.1a-6.3a or 7.1b-7.3b is adjoined at a distance a2 or b2 in the circumferential direction U by a respective mixing air hole of a neighbouring segment 322a or 322b. This distance a2 or b2 corresponds here to half the length of the base of the respective virtual triangle LDa, LDb and therefore to half of the distance a1 or b1. In a respective other row 7a or 6b of the same wall segment 320a or 320b, in which precisely two mixing air holes 7.1a, 7.2a or 6.1b, 6.2b are provided, a new mixing air hole follows in the circumferential direction U on a neighbouring segment 322a or 322b only at a greater distance. In the embodiment variant illustrated, a distance of 3/2 a1 or 3/2 b1 is provided here by way of example. At least for one group of rows 6a, 7b of adjacent wall segments 321a/b, 320a/b, 322a/b following one another in the circumferential direction U, this results in a local concentration of mixing air holes in the region of the segment boundaries SL with an accumulation of mixing air holes, axially offset with respect thereto, on the respective other combustion chamber wall. This is likewise required for moderating the temperature of the fuel-air mixture produced beyond the segment boundaries SL.

[0048] The two rows of wall segments 321a/b, 320a/b and 322a/b are each provided at an axial row distance c from one another. This row distance c is predefined here with respect to the wall distance d. Thus, the intention for the row distance c is that it lies in the range of 0.05 d to 0.4 d. As is illustrated with reference to the sectional illustration of FIG. 3, mixing air holes, which are offset axially from one another, of the outer and inner combustion chamber walls 320a, 320b are therefore present at a comparatively small distance from one another. This leads in combination with the inverse arrangement, which is repeating segment by segment, of the mixing air arrangements La, Lb, specifically in the case of the comparatively large pitch-height ratio p/d illustrated here, to an extremely efficient mixing of the fuel, which is injected in each case at the nozzle head 2A, with supplied mixing air with a comparatively uniform temperature distribution at the combustion chamber outlet. The result is comparatively low NOx emissions in the combustion of the fuel-air mixture.

LIST OF DESIGNATIONS

[0049] 111 Low-pressure compressor
112 High-pressure compressor
113 High-pressure turbine
114 Medium-pressure turbine
115 Low-pressure turbine
2 Fuel nozzle
2A Nozzle head
22 Outer housing
30 Combustion space
32a, 32b Inner/outer combustion chamber wall

320a, 320b Segment

[0050] 321a, 321b, 322a, 322b Neighbouring segment
33 Turbine inlet guide vane row
34a, 34b Inner/outer combustion chamber shingle
35 Mixing air hole
36 Air supply

4 Bolt

5 Nut

[0051] 6.1a, 6.2a, 6.3a Mixing air hole
6.1b, 6.2b
6a, 6b 1st row of mixing air holes
7.1a, 7.2a, Mixing air hole
7.1b, 7.2b, 7.3b
7a, 7b 2nd row of mixing air holes

A Outlet

a1, a2, b1, b2 Distance

[0052] B Bypass duct
BK Combustion chamber
c Axial row distance
C Outlet cone
d Wall distance
DL Nozzle axis

E Inlet/intake

F Fan

[0053] F1, F2 Fluid flow
FC Fan casing
La, Lb Mixing air hole arrangement

LDa, LDb Triangle

[0054] M Central axis/axis of rotation
ML Axis of symmetry

p Width/pitch

[0055] r Radial direction
R Manufacturing direction
S Rotor shaft
s Main direction of flow
SL Segment boundary line
T (Turbofan) engine

TT Turbine

[0056] U Circumferential direction

V Compressor

[0057] x Axial direction
Z Inflow direction