Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/005—Combined with pressure or heat exchangers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
  • F23R3/04—Air inlet arrangements
  • F23R3/10—Air inlet arrangements for primary air

Definitions

• the present invention relates to the field of gas turbine engine combustion chambers for aircraft.
• combustion chambers comprising:
• inner and outer walls respectively (also called inner and outer shells, or longitudinal walls), and
• a chamber bottom extending between said inner and outer walls and comprising first mounting apertures for injecting (in particular) combustion air devices for injecting this oxidant through said openings.
• a deflector is also often disposed downstream of the bottom wall, to protect it thermally vis-à-vis the focus of the combustion chamber in which the combustion takes place, the deflector having second mounting openings said oxidant injection devices (that is, configured for this purpose), the first and second openings then being a priori coaxial.
• the focus of a combustion chamber is defined by said longitudinal walls and the chamber bottom.
• baffle typically, two main functions of a baffle are to thermally protect the chamber floor, which is often more structural, and to create a film "cup" for the upstream cooling of (surfaces oriented towards the interior of the chamber internal and external walls, thanks to the impact flow from the pierced chamber bottom. Nevertheless, it turns out that this flow rate in the primary zone of the hearth (upstream part) disturbs the stability of the combustion and the early cooling of the inner walls. and / or external accentuates the critical zone thermal gradient, around holes through them typically called primary and / or dilution holes [006]
• fuel injection devices for injecting fuel through at least said first openings are also provided on these combustion chambers.
• - axial has for direction: extending (substantially) parallel to the general axis of the supply system (or injection) of combustion air and fuel injector heads, which general axis is also that of said first aforementioned mounting openings;
• upstream and downstream are to be considered with reference to the direction of general circulation of the air in the combustion chamber, the air here concerned coming from upstream (from the compressor (s)), with fuel enter into the hearth through the chamber bottom, the gases from the combustion exiting downstream to then pass into the (the) turbine (s).
• FR 2 998 038 discloses a combustion chamber in which there is a bottom chamber with two walls: upstream and downstream, the second acting as a deflector, with a space (or enclosure) between them, this space being supplied with air via multi-perforations, to ensure an impact cooling of the downstream wall, which is directly exposed to the radiation of the flame.
• the air is then ejected through slits or holes in the direction of the (said inward facing surfaces of the chamber of) the inner and outer walls to initiate a film of air which is then relayed through the multi-holes. -perforations of these walls.
• the chambers of such combustion chambers are particularly concerned.
• a technical problem addressed here relates to the degradation of the operating state of the chamber bottom. It has indeed been observed burns at the location of the chamber floor. Cracks have also been observed.
• the air passage holes are formed in the baffle and not in the wall (structural) of the chamber bottom. These air passage holes pass essentially between said chamber bottom wall and the baffle. It would be complicated to modify such a structure in order to pierce said chamber bottom wall, instead of the baffle, because said chamber wall has a role of mechanical structuring of the combustion chamber unlike the baffle.
• bottom wall connected to said longitudinal walls and extending transversely thereto, the bottom wall comprising:
• holes therethrough for the passage of cooling air between at least one inlet orifice and at least one outlet orifice of said holes, the holes extending along the bottom wall inside of that here, the outlet orifice being located closer to the said at least one opening as the inlet port, and
• a curved portion forming a flange, and - at least one combustion air supply system comprising a bowl mounted in said at least one opening, or one piece with said at least one bottom wall,
• each of these holes will thus be able to ensure a circulation of cooling air powered by the highest pressure differential available.
• the air flow obtained will recover calories by pumping in the chamber floor.
• the use of a deflector can be minimized (see below).
• the inlet orifice of (the) holes in question will be located towards an outer periphery of the chamber bottom wall.
• the combustion chamber [020]
• the combustion chamber :
• said at least one inlet is preferably located towards a free end of the flange (so possibly at a distance from the free end of the flange).
• said holes will lead to the edge of the chamber bottom wall at the location of the inlet and / or outlet ports.
• At least some of said holes may individually define a sinuous line over at least part of their length.
• an aircraft gas turbine engine combustion chamber in itself, comprising:
• At least one said bottom wall of a chamber with all or some of the aforementioned characteristics, connecting these longitudinal walls, and
• At least one said combustion air supply system comprising a bowl mounted in said at least one opening, or one piece with said at least one chamber bottom wall which is provided.
• the system (s) for supplying combustion air will also comprise at least one feed passage to an outer periphery of the bowl, and / or at least one twist, provided ( e) (s) respectively to be supplied (e) (s) combustion air to bring inside the bowl, mixed with the air having passed through said second holes.
• the aforementioned bowl is (typically at the location of a flared portion) traversed by second holes and / or third fluid passage holes (a priori only to the air).
• second holes and / or third holes will emerge in the combustion chamber firebox and, close to them, may open at least some of the outlet orifices (at least some) of said holes in the chamber bottom wall, so that (heated) air having passed through these holes can also pass through said second and / or third holes, thus in the direction of said focus.
• FIG. 1 is a diagram of a gas turbine engine combustion chamber according to the prior art
• Figure 2 is a section along the direction II-II of Figure 3 of an upstream portion of gas turbine engine combustion chamber, bottom wall according to the invention
• FIG. 3 is a diagram of a sector of this bottom wall fixed with said inner and outer walls of said chamber;
• FIG. 4 is an enlarged diagram of said sector of the bottom wall;
• Figure 5 shows a bypass of a fixing screw;
• FIGS. 6, 7 schematize forms of said holes or air ducts passing through the bottom wall of the chamber, FIG. 7 also having a local enlargement;
• Figure 8 is a sinuous shape diagram of said holes or air ducts.
• FIGS. 9, 10, 11 schematize alternatives to the embodiment of FIG. 2.
• Figure 1 illustrates a combustion chamber 10 of a turbomachine
• the turbomachine 1 comprises, upstream (AM) with respect to the overall direction of circulation of the gases in the turbomachine (arrow 11), a compressor, not shown, in which air is compressed before being injected by an annular diffusion duct into an outer housing of chamber 5, then in the combustion chamber 10 mounted in this outer casing 5.
• the compressed air is introduced into the combustion chamber 10 and mixed with fuel from injectors 12.
• the gases from the combustion are directed to a high pressure turbine (not shown) located downstream (AV) from the outlet of the chamber 10.
• the combustion chamber 10, which is of the annular type, has a radially inner wall 14 and a radially outer wall 16 (called also longitudinal walls), whose upstream ends are connected by a bottom wall 18 extending substantially radially.
• the bottom wall 18 has a plurality of axial openings 19 for mounting devices 20 for injecting combustion air also called combustion air supply systems.
• Fuel injector heads 12 are moreover engaged in front of the openings 19. Holes, dilution and / or cooling air circulation, 140 and 160, can pass through the inner and outer walls 14 and / or 16, respectively.
• the longitudinal walls 14 and 16 may be substantially coaxial with each other and parallel to the axis 22a, this axis belonging to the plane section 1, 2 and 9-11 and thus being the general axis of alignment of each device 20 for injecting combustion air and each fuel nozzle head 12 associated.
• the combustion chamber 10 develops on the other hand, annularly, around the axis X which is the general axis of the turbomachine 1 around which turn the rotating elements of (the) compressor (s) and the (the) turbines. In the example, an acute angle exists between the X and 22a axes. These two axes could be parallel.
• the chamber bottom 18 of the combustion chamber 10 further comprises deflectors 24 mounted downstream of the bottom wall 18 and intended to protect it from the flame formed in the combustion chamber 15 of the combustion chamber 10, defined between the walls 14.16.
• the deflectors 24 are arranged, in successive sectors around the axis X, adjacent to each other by their lateral edges, so as to form an annular ring of baffles.
• the bottom wall 18 comprises multiperforations 28 for the passage of air from the compressor and opening into the annular space 30 formed between the bottom wall 18 and the baffles 24.
• the ventilation of the bottom wall 18 can not be homogeneous over its entire circumference.
• annular wall 118 of annular combustion chamber bottom interconnecting through fasteners (such as screws 32), the longitudinal walls 114, 116, substantially transversely to them.
• the bottom wall 118 has:
• apertures 119 for mounting the combustion air supply systems and holes 128 therethrough, for the passage of cooling air, between at least one inlet port 128a and at least one outlet port 128b of these holes.
• the cooling air passage holes 128 through the wall of bottom 118 extend interiorly along this bottom wall, between at least one said inlet port 128a and at least one said outlet port 128b.
• the outlet orifice 128b is located closer to the opening 119 than the inlet port 128a, as best seen in FIG. 4.
• the bottom wall 118 will preferably comprise, around the axis 122a, a circumferential succession of wall sectors 148a each provided with an opening 119; see in particular Figure 3.
• the bottom wall 118 has, at its outer periphery, an annular flange 138a for attachment to the upstream end of the outer wall 116 of the chamber, and, at its inner periphery, an annular rim 138b fastening to the upstream end of the inner wall 114 of the chamber.
• outer annular flanges 138a and 138b internal are facing upstream. They can be substantially cylindrical.
• the attachment itself is, in the preferred example, provided by means of the screw-nut type 32 which pass through orifices 34 formed in the flanges 138a, 138b, radially to the axis 122a; see figure 5.
• the holes 128 may also lead to the inner edge 168c of the bottom wall; see figures 3.9.
• the section of the holes 128 may be constant or variable. It may be rectangular ( Figure 6) or circular ( Figure 7), for example.
• the number of entries 128a and the number of outputs 128b will be defined as needed. At an entrance will not necessarily correspond to a single exit; and vice versa. For example, it is possible to provide a single inlet mouth 128a in the form of a long slot, connections 36 internal to the chamber bottom ( Figure 7) or exits in different places; for example, an outlet at the air injection system (bowl and flange holes) and an outlet along the wall 118.
• Diameters e1 of holes / pipes 128 less than one millimeter should allow to maintain a thickness (e2a + e2b) of low chamber floor and a guaranteed structural role. A minimum thickness of material will thus be preserved. These diameters will be favorably of the order of a quarter to a third of the total thickness (e1 + e2a + e2b) of the chamber bottom.
• Figures 2 and 9-11 schematically detail the environment of the wall 118 of the chamber bottom. Thus, it is found that the combustion chamber 101 is fed with liquid fuel mixed with air.
• the liquid fuel is fed thereto by the fuel injector heads 112 engaged opposite (just upstream) the openings 119, along each axis 122a, after having each passed through the axial opening 37 of an annular shroud 39 fixed peripherally to the walls 114,116.
• the vaporization of the fuel is continued at a venturi 38 and a pre-spraying bowl 40 of generally annular shape, typically frustoconical, by the effect of the pressurized air coming from the compressor supra.
• the pressurized air passes through one or more radial swirlers 42 of the corresponding system 120, to ensure a rotation of the fuel sprayed by the fuel injector head 112 coaxial with said system 120 concerned .
• Each radial auger may comprise an upstream auger 42a and an auger ava 42b, adjacent.
• Each bowl 40 may have a downstream end flange 44 forming an outer rim, which may be radial. The tendrils could also be axial.
• Figures 2,10-11 show, with simple arrows, different air supply paths to the fireplace 115 and, Figure 2, by a double arrow, a fuel supply path to the same home 115, which extends axially from the wall 118 of the chamber bottom, between the longitudinal walls 114,116.
• Each bowl 40 of the combustion air supply system 120 is mounted in (or surrounds, in a monobloc embodiment, see below) the opening 119 of one of the sectors of the chamber bottom wall. 118.
• the bowl 40 is crossed by the air and the fuel to ignite in the fireplace 115.
• the compressed cooling air having circulated in the holes / pipes128, can come out by: second holes 46 passing through the bowl 40, obliquely, in the direction of the axis 22a, and / or
• the third holes 48 are substantially parallel to the axis 122a.
• the air having circulated in the holes / channels 128 will preferably come out through the edge of the wall 118, 128b (see Figures 2,9-11), to supply an intermediate air distribution chamber 50, annular about the axis 122a.
• the distribution chamber 50 is closed upstream by an angled wall 52 connected to the wall 118, towards its inner edge, and to the bowl 40.
• the bent wall 52 may be traversed by at least one passage 54 to supply, in the distribution chamber 50, air from the stream 111 but not through the holes / pipes128.
• each system 120 for supplying combustion air may comprise at least one said supply passage 54 to an outer periphery of the bowl, and / or at least one twist 42, provided (s) respectively to be fed (s) (e) (s) combustion air to bring inside the bowl 40, mixed with the air, from the wall 118 of the chamber bottom, and having thus passed through the second holes 46, for a supply of air directly to the location of the opening 119 considered.
• the outer periphery concerned of the bowl 40 and the second holes 46 will be favorably located in its downstream part 40a which flares downstream, in order to distribute the air / fuel mixture in the hearth 115.
• the bottom wall 118 and the system 120 may be welded together (especially brazed); cf. figure 2,
• the bottom wall 118 and the system 120 may be monoblock (especially if additive manufacturing); cf. Figures 9,10-11.
• the wall 118 has been bonded, around the periphery of the opening 119, to the outer face of the flared portion 40a of the bowl 40 and to the downstream end of the bent wall 52. in forming the annular chamber 50, the upstream ends of the bowl 40 and the bent wall 52 are further connected together.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Combustion Of Fluid Fuel (AREA)

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• 2018
  • 2018-05-23 FR FR1854298A patent/FR3081539B1/fr active Active
• 2019
  • 2019-05-22 WO PCT/FR2019/051176 patent/WO2019224484A1/fr unknown
  • 2019-05-22 EP EP19737577.7A patent/EP3797248A1/de active Pending
  • 2019-05-22 US US17/058,021 patent/US11365883B2/en active Active
  • 2019-05-22 CN CN201980042603.9A patent/CN112334705B/zh active Active

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