U.S. patent application number 14/972850 was filed with the patent office on 2016-06-23 for gas turbine combustion chamber with modified wall thickness.
The applicant listed for this patent is Rolls-Royce Deutschland Ltd & Co KG. Invention is credited to Miklos GERENDAS.
Application Number | 20160178198 14/972850 |
Document ID | / |
Family ID | 54783486 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160178198 |
Kind Code |
A1 |
GERENDAS; Miklos |
June 23, 2016 |
GAS TURBINE COMBUSTION CHAMBER WITH MODIFIED WALL THICKNESS
Abstract
A gas turbine combustion chamber, including at least one
combustion chamber wall in which mixed air holes are formed in a
predefined area that extends around the combustion chamber in a
ring-shaped manner with respect to the central axis of the
combustion chamber in a central area of the same, characterized in
that the combustion chamber wall has a greater thickness in the
ring-shaped area of the mixed air holes than in the areas that are
not provided with mixed air holes.
Inventors: |
GERENDAS; Miklos; (Am
Mellensee, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rolls-Royce Deutschland Ltd & Co KG |
Blankenfelde-Mahlow |
|
DE |
|
|
Family ID: |
54783486 |
Appl. No.: |
14/972850 |
Filed: |
December 17, 2015 |
Current U.S.
Class: |
60/753 ;
60/754 |
Current CPC
Class: |
F23R 3/04 20130101; F23R
3/002 20130101; F23R 3/06 20130101; F23R 3/007 20130101; F23R 3/50
20130101; F23R 2900/00005 20130101 |
International
Class: |
F23R 3/04 20060101
F23R003/04; F23R 3/00 20060101 F23R003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2014 |
DE |
10 2014 226 707.2 |
Claims
1. Gas turbine combustion chamber, comprising at least one
combustion chamber wall in which mixed air holes are formed in a
predefined area that extends around the combustion chamber in a
ring-shaped manner with respect to the central axis of the
combustion chamber in a central area of the same, wherein the
combustion chamber wall has a greater thickness in the ring-shaped
area of the mixed air holes than in the areas that are not provided
with mixed air holes.
2. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall has a substantially constant rigidity in
all areas, in particular in the longitudinal direction with respect
to the throughflow direction of the combustion chamber.
3. Gas turbine combustion chamber according to claim 1, wherein the
greater thickness of the combustion chamber is formed with a wall
thickness, wherein the maximal wall thickness is calculated based
on the following equation: W.sub.max=C.sup. {square root over
((A-Sr)/A)}W.sub.0 W.sub.max: maximal wall thickness W.sub.0:
nominal wall thickness A: distance between the hole centers of
neighboring holes Sr: sum of the hole radiuses of neighboring holes
C: power factor 0.7 . . . 1.3:
4. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall is embodied with a single layer.
5. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall is embodied with a double layer, and in
that at least one of the combustion chamber walls is provided with
a greater wall thickness in the area of the mixed air holes.
6. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall is manufactured as a cast part.
7. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall is manufactured by means of a generative
method.
8. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall is manufactured from contoured sheet metal
materials.
9. Gas turbine combustion chamber according to claim 1, wherein the
combustion chamber wall is manufactured from a fiber-reinforced
ceramic material.
Description
[0001] This application claims priority to German Patent
Application DE102014226707.2 filed Dec. 19, 2014, the entirety of
which is incorporated by reference herein.
[0002] The invention relates to a gas turbine combustion chamber
according to the generic term of claim 1.
[0003] In particular, the invention relates to a gas turbine
combustion chamber with at least one combustion chamber wall,
inside of which mixed air holes are formed in predefined areas.
[0004] It is known from the state of the art to provide mixed air
holes in combustion chamber walls of gas turbines, through which
additional air is guided into the interior of the combustion
chamber.
[0005] As far as the state of the art is concerned, reference is
made to EP 1 528 322 A2, EP 1 795 809 A2 or U.S. 2002/0116929
A1.
[0006] Through the mixed air holes, a considerable weakening is
introduced into the combustion chamber wall at a particular axial
position. As the share of mixed air is increased through a better
cooling and/or through enhanced, more solid wall materials, it is
possible to configure the mixed air holes to be bigger. As a
result, the strength of the combustion chamber wall is increasingly
weakened. This weakening occurs due to the fact that single-layer
or double-layer combustion chamber walls are manufactured from
sheet metals or cast parts with a constant wall thickness. Cracks
occur as a consequence of this material weakening. Here, the crack
growth from mixed air hole to mixed air hole is a significant
factor when it comes to the failure of combustion chamber walls.
Thus, the danger of failure increases with an increasing share of
mixed air.
[0007] The invention is based on the objective of creating a gas
turbine combustion chamber of the kind that has been mentioned in
the beginning, in which the disadvantages of the state of the art
are avoided and which in particular has a sufficient strength in
the area of the mixed air holes, while at the same time having a
simple structure and being manufacturable in a cost-effective
manner.
[0008] According to the invention, the objective is achieved by the
combination of features of claim 1, with the subclaims showing
further advantageous embodiments of the invention.
[0009] Thus, it is provided according to the invention that the
combustion chamber has a greater wall thickness in the area of the
mixed air holes than in the areas that are not provided with mixed
air holes.
[0010] The mixed air holes are arranged in a middle area of the
combustion chamber with respect to the axial extension of the
combustion chamber, and in the circumferential direction of the
combustion chamber. According to the invention, this ring-shaped
circumferential area in which the mixed air holes are arranged is
provided with a greater wall thickness.
[0011] Thus, according to the invention, the thickness of the
load-bearing walls of the combustion chamber is locally increased
to the extent to which a load-bearing cross-section is removed
through the mixed air holes in the circumferential direction.
According to the invention, it is possible to use this solution in
single-layer as well as in double-layer combustion chamber walls.
As far as double-layer combustion chamber walls are concerned, it
is possible according to the invention to provide with a greater
thickness or to thicken only one layer, for example the
load-bearing external combustion chamber wall or the hot internal
combustion chamber wall, or both.
[0012] Thus, the solution according to the invention has the
advantage that the rigidity of the combustion chamber wall no
longer varies in the longitudinal direction, but is instead
constant in particular in the area of the mixed air holes, and in
particular as compared to the areas in which no mixed air holes are
formed. In this way, deformations through external loads are not
concentrated in the area that is provided with the mixed air holes.
Furthermore, a gap that can emerge between the shingle (internal
combustion chamber wall) and the shingle support (external
combustion chamber wall) becomes smaller thanks to the constant
rigidity.
[0013] While in the constructions that are known from the state of
the art the crack growth from one mixed air hole to another is a
significant failure mechanism in the combustion chamber, the
thickening or increase in thickness of the combustion chamber wall
according to the invention provides for an increase in rigidity and
strength of the combustion chamber wall especially in the areas
that are weakened by the mixed air holes. In this manner it is
possible to minimize crack formation and crack growth. This is done
with a minimal material effort or a minimal increase in weight
through the thickening of the combustion chamber wall.
[0014] The invention can be used in combustion chamber walls that
are manufactured as cast parts as well as in combustion chamber
walls that are made by means of a generative method (laser
sintering, ALM, additive layer manufacturing). In combustion
chambers that are made of sheet metal it is possible according to
the invention to use specially contoured boards, or to manufacture
the thinner areas of the walls by means of flow turning.
[0015] In an analogous manner, the invention can also be used with
combustion chamber walls made of fiber-reinforced ceramic material
(CMC). Here, the number of layers of the ceramic fiber fabrics or
windings is locally increased in the area of the mixed air holes.
This entails only a small additional effort, since the wall is
principally composed of multiple layers. The number of layers is
merely increased in the area of the mixed air holes, for example
from 12 to 20. When it comes to CMC, the increase in wall thickness
is greater, since the wall temperature can be higher, meaning that
less cooling air has to be used, and thus more air is to be guided
through the mixed air holes, by which their diameter is increased
beyond what is possible in a metallic construction. The layers can
be inserted on the internal or the external side or as additional
intermediate layers with a limited axial extension.
[0016] In addition, when it comes to particular patterns of mixed
air holes in a double-wall combustion chamber, it is advantageous
if there is no more narrow web between the mixed air holes where
the mixed air holes are in close proximity to one another, and if
the two mixed air holes that are located in close proximity to one
another in the shingle are instead supplied with air through a
single opening in the cold combustion chamber wall. Through the
elimination of the web the shingle can be thickened towards the
exterior. This can also be done in the form of a rib on the cold
side of the shingle, which then protrudes through the opening in
the cold combustion chamber wall.
[0017] In any case, the increase in thickness of the combustion
chamber wall is effected in such a manner that the mixed air holes
do not reduce the rigidity of the combustion chamber wall.
[0018] In the following, the invention is described in connection
to the drawing by referring to exemplary embodiments. Herein:
[0019] FIG. 1 shows a schematic rendering of a gas turbine engine
according to the present invention,
[0020] FIG. 2 shows a longitudinal cross-section of a combustion
chamber according to the state of the art,
[0021] FIG. 3 shows a schematic view of an arrangement of mixed air
holes according to the state of the art,
[0022] FIG. 4 shows a view, analogous to FIG. 3, of an arrangement
of mixed air holes according to the invention,
[0023] FIG. 5 shows a schematic side view of a combustion chamber,
analogous to FIG. 2, of a first exemplary embodiment of the
invention, and
[0024] FIG. 6 shows a view, analogous to FIG. 5, of another
exemplary embodiment of the invention.
[0025] The gas turbine engine 110 according to FIG. 5 represents a
general example of a turbomachine in which the invention can be
used. The engine 110 is embodied in the conventional manner and
comprises, arranged in succession in the flow direction, an air
inlet 111, a fan 112 that is circulating inside a housing, a
medium-pressure compressor 113, a high-pressure compressor 114, a
combustion chamber 115, a high-pressure turbine 116, a
medium-pressure turbine 117 and a low-pressure turbine 118, as well
as an exhaust nozzle 119, which are all arranged around a central
engine axis 101.
[0026] The medium-pressure compressor 113 and the high-pressure
compressor 114 comprise multiple stages, respectively, with each of
these stages having an array of fixedly attached stationary guide
blades 120 extending in the circumferential direction, which are
generally referred to as stator blades and which protrude radially
inwards from the core engine housing 121 through the compressors
113, 114 into a ring-shaped flow channel. Further, the compressors
have an array of compressor rotor blades 122 that protrude radially
outwards from a rotatable drum or disc 125, [and] which are coupled
to hubs 126 of the high-pressure turbine 116 or of the
medium-pressure turbine 117.
[0027] The turbine sections 116, 117, 118 have similar stages,
comprising an array of fixedly attached guide blades 123 which are
protruding through the turbines 116, 117, 118 in a radially inward
direction from the housing 121 into the ring-shaped flow channel,
and a subsequent array of turbine blades 124 that are protruding
externally from a rotatable hub 126. In operation, the compressor
drum or compressor disc 125 and the blades 122 arranged thereon as
well as the turbine rotor hub 126 and the turbine rotor blades 124
arranged thereon rotate around the engine axis 101.
[0028] FIG. 2 shows an enlarged longitudinal section view of a
combustion chamber wall as it is known from the state of the art.
Here, a combustion chamber 1 with a central axis 25 is shown,
comprising a combustion chamber head 3, a base plate 8 and a heat
shield 2. A burner seal is identified by the reference sign 4. The
combustion chamber 1 has an external cold combustion chamber wall 7
to which an internal, hot combustion chamber wall 6 is attached.
For the supply of mixed air, mixed air holes 5 are provided. With a
view to clarity, impingement cooling holes and effusion holes have
been omitted in the rendering.
[0029] The internal combustion chamber wall 6 is provided with
bolts 13, which are embodied as threaded bolts and are screwed in
by means of nuts 14. The mounting of the combustion chamber 1 is
carried out by using combustion chamber flanges 12 and combustion
chamber suspensions 11.
[0030] Combustion chamber walls that are known from the state of
the art and are made of sheet metal usually have a constant
thickness in the range of 0.9 to 1.6 mm, while the combustion
chamber walls that are manufactured as cast parts have wall
thicknesses of between 1.2 and 2.5 mm.
[0031] FIGS. 3 and 4 show the arrangement of mixed air holes in a
schematic side view of a combustion chamber wall. For example, FIG.
3 shows the allocation of mixed air holes as they are known from
the state of the art. It is to be understood that the modification
of the wall thickness and thus the rigidity of the combustion
chamber wall depends on the arrangement and the pattern of the
mixed air holes. Here, it is in particular the axial distance and
the circumferential distance of the mixed air holes that has to be
taken into account. The respective cross-sections of the mixed air
holes play a role, as well.
[0032] The greater thickness (W) of the combustion chamber (6, 7)
is formed with a wall thickness, wherein the maximal wall thickness
is calculated based on the following equation:
W.sub.max=C.sup. {square root over ((A-Sr)/A)}W.sub.0 [0033] With
[0034] W.sub.max: maximal wall thickness [0035] W.sub.0: nominal
wall thickness [0036] A: distance between the hole centers of
neighboring holes [0037] Sr: sum of the hole radiuses of
neighboring holes [0038] C: power factor 0.7 . . . 1.3: to be
selected by the design engineer based on previous experience. This
factor can take on different values for different applications
(depending on experience).
[0039] Thus, i.e. for a power factor=1, the following instruction
results:
[0040] If the remaining web thickness between neighboring mixed air
holes falls below the sum of the cross-sections of the two mixed
air holes by more than 20%, the wall thickness is increased by at
least 27%.
[0041] If the remaining web thickness between neighboring mixed air
holes falls below the mean value of the cross-sections of the two
mixed air holes, the wall thickness is increased by substantially
41%.
[0042] If the remaining web thickness between neighboring mixed air
holes falls below the mean value of the radiuses of the two mixed
air holes, the wall thickness is increased by substantially
73%.
[0043] Here, it is irrelevant whether the smallest web thickness
occurs between the mixed air holes of a row or between the mixed
air holes of neighboring rows. This determines only the axial
position of the maximal wall thickness. If the smallest web
thickness lies between the mixed air holes of a row, the maximum of
the wall thickness lies at the axial position of the axes of the
mixed air hole row. If the minimal web thickness lies between the
mixed air holes of neighboring mixed air hole rows, the maximal
wall thickness lies between the central axes of the two rows of the
mixed air holes substantially in the middle between the rows.
[0044] The axial extension of the thickening for a mixed air hole
row is substantially limited to the area between an upstream hole
diameter and a downstream hole diameter.
[0045] The axial extension of the thickening for two mixed air hole
rows is substantially limited to the area between a hole diameter
of the upstream mixed air hole row in the upstream direction and a
hole diameter of the downstream mixed air hole row in the
downstream direction.
[0046] If different mixed air hole diameters are present in one
row, the largest diameter of the respective hole row applies with
respect to these limitations.
[0047] In order to simplify the manufacturing process, the
enlargement of the wall thickness can be realized in a ramp in
front of the ligament that determines the thickness, followed by an
area of constantly high wall thickness in the area of the mixed air
holes and a ramp back to a smaller wall thickness, which is then
substantially maintained up until shortly before the end of the
combustion chamber. Here, the substantially constant wall thickness
in front of the mixed air hole row does not have to be identical to
the substantially constant wall thickness downstream of the same.
In this manner, the transitions in wall thickness are designed so
as to be fluid in order to avoid voltage peaks through
cross-sectional jumps.
[0048] According to the invention, it is for example possible to
increase the sheet metal thickness of the external cold combustion
chamber wall 7 from 1.2 mm to 1.6 mm, while the thickness of an
internal hot combustion chamber wall 6 that is embodied as a cast
part is increased in the area of the mixed air holes from 1.4 mm to
2 mm. Thus it is possible in known patterns or arrangements of
mixed air holes 5 to achieve a modification of the rigidity through
an increase of the wall thickness, namely in such a manner that any
weakening of the walls which occurs without the thickening is
compensated for.
[0049] FIG. 4 illustrates an embodiment that is possible according
to the invention in which the two mixed air hole rows are
considerably approximated in the circumferential direction or
almost overlap. Without an increase in wall thickness, as it is
provided according to the invention, the weakening of the
combustion chamber wall would be further increased. Thus, according
to the invention, a stronger thickening is effected in this area,
as will be described in the following in connection to FIGS. 5 and
6. For example, a sheet metal thickness of a combustion chamber
wall can be increased from 1.2 mm to 1.8 mm. According to the
invention, the wall thickness of a cast part of 1.4 mm can for
example be increased to 2.5 mm in the area where the mixed air
holes overlap.
[0050] As has been mentioned, the invention can be used in
single-wall as well as in double-wall combustion chambers. In a
combustion chamber with a single-wall, the wall thickness of the
sheet metal is for example increased in the area of the mixed air
holes, or the cross-section of the adjoining area which is not
provided with mixed air holes is reduced by means of flow turning.
Through the flow turning, standardized sheet metal thicknesses are
abandoned to arrive at a wall thickness that is adjusted to the
local requirements. Structural components with locally adjusted
wall thickness that are produced by means of flow turning can be
manufactured in a more cost-effective manner as compared to
structural components that are mated from multiple sheet metals,
forged or cast parts. If a combustion chamber wall has a
multi-layer wall construction, which is for example manufactured as
a cartridge or by mating laminated sheet metals, it is possible
according to the invention to adjust the wall thickness in the area
of the mixed air holes analogously to the local requirements.
[0051] FIG. 5 shows a sectional view of a combustion chamber wall
that is analogous to FIG. 2. In FIG. 2, the wall thickness across
the length of the combustion chamber wall is represented in the
form of a diagram in the top part of the image. As can be seen from
it, the combustion chamber wall has a constant wall thickness W
across its entire length. In contrast to that, a thickening of the
wall in the area of the mixed air holes 5 and thus a greater wall
thickness is provided in the exemplary embodiment shown in FIG. 5,
as can be seen in the diagram in the top half of the image of FIG.
5.
[0052] FIG. 5 shows a sectional view of a construction in which the
external cold combustion chamber wall 7 as well as the internal hot
combustion chamber wall 8 are configured in a thickened manner. In
this way, the reduction of the cross-section of the two combustion
chamber walls 7, 8 that is available in terms of strength is
compensated for by the thickening.
[0053] FIG. 6 shows another exemplary embodiment in a rendering
that is analogous to FIG. 5. As can be seen here, a further
increase in wall thickness occurs in addition to the thickening or
increase in wall thickness in the area between the mixed air holes
5 or in the area of their overlapping (see also FIG. 4) as it is
provided in FIG. 5. This can particularly also be seen in the
diagram in the top half of the rendering in FIG. 6.
PARTS LIST
[0054] 1 combustion chamber
[0055] 2 heat shield
[0056] 3 combustion chamber head
[0057] 4 burner seal
[0058] 5 mixed air
[0059] 6 internal, hot combustion chamber wall/segment/shingle
[0060] 7 internal, cold combustion chamber wall
[0061] 8 base plate
[0062] 9 central axis
[0063] 10 sealing lip
[0064] 11 combustion chamber suspension
[0065] 12 combustion chamber flange
[0066] 13 bolt
[0067] 14 nut
[0068] 101 engine central axis
[0069] 110 gas turbine engine/core engine
[0070] 111 air inlet
[0071] 112 fan
[0072] 113 medium-pressure compressor (compactor)
[0073] 114 high-pressure compressor
[0074] 115 combustion chamber
[0075] 116 high-pressure turbine
[0076] 117 medium-pressure turbine
[0077] 118 low-pressure turbine
[0078] 119 exhaust nozzle
[0079] 120 guide blades
[0080] 121 engine cowling
[0081] 122 compressor rotor blades
[0082] 123 guide blades
[0083] 124 turbine blades
[0084] 125 compressor drum or compressor disc
[0085] 126 turbine rotor hub
[0086] 127 outlet cone
[0087] W wall thickness
* * * * *