NOZZLE FOR SUPPLYING AIR AND LIQUID FUEL INTO A COMBUSTION CHAMBER

Abstract

The invention relates to a nozzle for supplying air and liquid fuel into a combustion chamber (30), in particular of an aircraft engine, with a nozzle main body (10) aligned along a nozzle longitudinal axis (L), in which are arranged: - at least one first air duct (14) running on and / or around the nozzle longitudinal axis (L), - at least one fuel channel (16) arranged radially outwardly, in particular in a ring-shaped manner, around the first air channel (14) and - at least one second air duct (121) arranged radially outwardly, in particular in a ring-shaped manner, around the fuel duct (16), wherein the fuel duct (16) opens with an outlet opening (24, 241, 242, 243) on an at least substantially axially aligned film-laying surface (20) with a downstream trailing edge (22). A nozzle for stable and low-emission combustion chamber operation is provided in that the fuel channel (16) upstream of the film-laying surface (20) has at least two fuel channel sections (161, 162, 163) which are connected in parallel to one another in terms of flow, in particular running in a ring around the longitudinal axis (L) of the nozzle, wherein an outlet opening (241, 242, 243) is arranged at each of the downstream ends of the fuel channel sections (161, 162, 163) and a surface section (201, 202, 203) of the film-laying surface (20) is arranged downstream of the outlet opening.

Description

The invention relates to a nozzle for supplying air and liquid fuel into a combustion chamber, in particular of an engine of an aircraft, having a nozzle main body which is aligned along a nozzle longitudinal axis and in which are arranged:at least one first (central) air duct running on and / or around the nozzle longitudinal axis,at least one fuel channel arranged radially on the outside, in particular annularly circumferentially, around the first air channel, andat least one second air duct arranged radially on the outside, in particular annularly circumferentially, around the fuel duct,wherein the fuel channel with an outlet opening opens with a downstream trailing edge on a film-laying surface oriented at least substantially axially, i.e. with a greater axial than radial directional component.Such a nozzle, which is assigned to the air jet atomizing nozzles according to its operating principle, is disclosed in DE 10 2017 218 529 A1. In this case, an annular fuel channel is present around a central air channel and, around the latter, two radially offset annular air guiding channels are present in turn. When the fuel exits onto the film-laying surface, the fuel film is transported by the air flowing past the central air duct in the direction of the trailing edge and, after outflow, atomized into fine droplets between the central air stream and one of the outer air streams.A further nozzle of this type is known from U.S. Pat. No. 9,423,137 B2. In this known nozzle for adding liquid fuel into a combustion chamber, a plurality of radially offset fuel channels are present, via which fuel is added into different air channels.Further nozzles for supplying air and liquid fuel into a combustion chamber are known from US 2014 / 0241871 A1, US 2020 / 0141582 A1, US 2022 / 0099290 A1, US 2016 / 0047315 A1 and US 2010 / 0229556 A1.Investigations by means of high-resolution flow simulations have shown that the process of outflow of the fuel from the film-laying surface is subject to fluctuations, in some cases periodic fluctuations. These fluctuations consist, on the one hand, in the build-up and collapse of fuel waves as a result of the interaction with the overflowing air at the fuel outlet opening. In this way, large liquid stream filaments can form on leaving the trailing edge, which break down further downstream into relatively large droplets. On the other hand, fluctuations result due to wavy loading of the film-laying surface with fuel exiting from the fuel outlet opening. As a result of the fluctuations in the fuel mass flow and the resulting droplet size distribution, pressure fluctuations / thermoacoustics which are related to the flame dynamics can occur and the pollutant formation within the combustion chamber can be adversely influenced.The object of the invention is to provide a nozzle for stable and low-pollutant operation of a combustion chamber, and also an engine which can be operated stably and low-pollutant.The invention is achieved for the nozzle having the features of claim 1 and for the engine having the features of claim 14. In the nozzle, it is provided that the fuel channel upstream of the film-laying surface has at least two fuel channel sections connected fluidically in parallel to one another (i.e. arranged in a fluidic parallel connection, not in series), in particular running annularly around the nozzle longitudinal axis, wherein an outlet opening is arranged in each case at the downstream ends of the fuel channel sections and a surface section of the film-laying surface is arranged in each case (preferably directly, directly adjoining the outlet opening) downstream of the latter.The nozzle is in particular at least substantially rotationally symmetrical.The fuel duct sections are fluidically connected in parallel to one another for guiding partial mass flows, wherein all partial mass flows in total result in the total fuel flow guided through the fuel duct.The film-laying surface is preferably arranged adjacent to the first air duct for overflow with an air stream flowing through the first air duct.The film-laying surface is designed as a surface, in particular an annular surface, which is subdivided into the at least two surface sections by means of the outlet openings, preferably annular gaps. The surface sections are thus assigned to the film-laying surface and / or together form the film-laying surface. In this way, the fuel introduced into the combustion chamber by means of the nozzle is applied to the film-laying surface through at least two outlet openings. This reduces or prevents an accumulation of fuel from the total mass flow at an individual outlet opening. Wave formation or fluctuations in the fuel mass flow are significantly reduced, which is associated with more uniform combustion combined with significantly increased stability and reduced pollutant emission, in particular soot formation.In a preferred embodiment variant, the at least two surface sections are arranged axially one behind the other, non-overlapping, and e.g. radially offset from one another (stepwise) (alternatively unstuffed, radially at the same height), each interrupted by one of the outlet openings, which are also arranged axially offset one behind the other (and in particular radially at the height of the surface section arranged in each case downstream). Due to the arrangement one behind the other without overlapping in the axial direction, all surface sections can be overflowed by the air flow. In the case of the radial offset, for example, the surface section arranged furthest upstream can be slightly offset radially outwards or inwards with respect to the inner wall of the first air duct arranged upstream thereof. The surface section / s arranged axially downstream / n surface section / s can / can be offset further radially outwards, if appropriate. For example, the radial offset may be configured to approximately correspond to the increase in film thickness of fuel at each exit orifice, respectively. For example, with a radial inward offset, the flow velocity of the overflowing air flow may be increased, which may be advantageous for atomizing the fuel.Preferably, the at least two surface sections each have a surface length in the direction of the nozzle longitudinal axis which corresponds to between a factor of 2 and a factor of 10, in particular between a factor of 3 and a factor of 5, of the axial dimension (length dimension arranged parallel to the nozzle axis) of the outlet opening arranged upstream on the respective surface section. The surface sections can be of the same length or of different lengths. In total, a film-laying surface is thus obtained which is significantly enlarged axially compared to the prior art (e.g. longer by a factor of 1.5 to 4) and extends (immediately following) downstream of the outlet opening arranged furthest upstream as far as the trailing edge, wherein it is interrupted by at least one further outlet opening and is divided axially into the at least two surface sections.In a preferred embodiment variant, the at least two fuel duct sections each have an axial section and / or a downstream end section, which is arranged in particular downstream and which is arranged in a manner adjoining it and is oriented inward in the axial-radial direction with respect to the nozzle longitudinal axis (and in the direction of the downstream nozzle end). The end section opens into the outlet opening.A favorable flow interaction of the fuel with the air flow flowing over the film-laying surface is achieved in particular in that the surface sections have a smaller radial directional component in their axial or axial-radial alignment than the end sections. The surface sections can be aligned, for example, exclusively axially, without radial directional component. In the circumferential direction, the surface sections then form in particular cylindrical (in the case of exclusively axial alignment) and / or conical (in the case of axial-radial alignment) sections within the nozzle relative to the nozzle longitudinal axis. In the case of an axial-radial alignment, in particular an inclination in the radial direction opposite to the air flow direction can be formed, wherein the interaction of the fuel film with the air flow is influenced during operation. In particular, the air flow flowing through the first air duct can thus strike the film-laying surface at a slight angle.The axial length, radial position and / or inclination of the individual surface sections can / can be configured identically and / or differently.In a preferred embodiment variant, at least one swirl generator is arranged in at least one, preferably in each, of the fuel duct sections, wherein preferably the at least one swirl generator is arranged, optionally in each case, in the axial section. In addition to the generation or reinforcement of a swirling flow (flow with superimposed tangential directional component) of the fuel, the swirl generators preferably also each serve as spacers and / or joining elements, as a result of which assembly advantages can be achieved: in this case, in particular, the nozzle can be produced in modular fashion, wherein the nozzle main body forms a radially innermost inner wall of the fuel duct. Fuel guide elements in the form of cylindrical-conical elements are, for example, successively plugged onto the base body. The cylindrical-conical elements each carry, for example, on the inside and / or outside of the cylindrical section, the swirl generators which form the points of contact with the adjacent components. A connection to the nozzle main body as an entire component can be produced by known methods, for example by means of welding and / or soldering technology.In a design variant that is easy to assemble and / or favorable to flow, the fuel channel is designed in such a way that the division of a total fuel flow supplied by means of the fuel channel into partial fuel flows within the fuel channel sections within the nozzle main body and / or in the flow direction takes place in stages (one after the other in terms of flow). The formation inside the nozzle main body brings manufacturing advantages in that a plurality of fuel passage portions need only be provided in a small part of the nozzle. The assembly can be carried out in modular fashion, for example as indicated in connection with the swirl generators, with their intermediate arrangement as spacers. The stepwise flow division, wherein, in the presence of more than two fuel duct sections (i.e. more than two partial fuel flows), the respective partial fuel flows are divided in series (one after the other in terms of flow) from the total fuel flow or the remaining mass flow, enables a particularly fluidically favorable (low-loss) division.In a preferred embodiment variant, the at least two fuel duct sections are separated from one another by means of at least one fuel guide wall, in particular a fuel guide element, at the upstream end of which a flow divider, in particular an acute angle flow divider, is optionally arranged in each case. If the fuel guide wall / s are formed as a fuel guide element / s, the (optionally respective) fuel guide element is present before assembly as a separate, for example cylindrically conical, component. The acute-angled flow divider is in particular wedge-shaped, wherein it is formed tapering at the upstream edge and has an angle of less than 90° downstream between the flanks running in the flow direction. In this way, the pressure loss during the flow division can be kept relatively low.In a design variant which is likewise fluidically favourable, in the presence of a plurality of fuel guide walls, in particular fuel guide elements, the upstream ends, together with the flow splitters, are arranged axially and / or radially offset with respect to one another. The axial offset is in particular such that a transition section leading from one flow divider to another flow divider and / or fuel channel section runs with a constant axial-radial alignment in the direction of the nozzle longitudinal axis and / or downstream nozzle end.It is preferably provided that the fuel channel upstream of a first flow divider has an, in particular exclusively, axially aligned overall section for conducting the entire overall fuel flow supplied by means of the fuel channel. Alternatively or additionally, an outer fuel channel section, in particular its axial section, is arranged downstream of the first flow divider. Preferably, the outer axial fuel passage section is arranged in extension of the axially aligned overall section. Alternatively or additionally to the outer fuel channel section, downstream of the first flow divider there is a, in particular axially radially oriented, transition section for transferring the fuel mass flow remaining from the total mass flow to a second flow divider and / or an axial section of a fuel channel section arranged radially further inward, e.g. middle (in the case of the presence of three fuel channel sections) or inner (in the case of the presence of two fuel channel sections), for example. In the case of more than three fuel channel sections present, the arrangement of further flow dividers and / or channel sections of the fuel channel is preferably effected analogously thereto.In favor of a demand-optimized design, the fuel passage sections, in particular their flow cross sections, can be designed such that during operation the total fuel flow is divided between at least substantially identical portions, or such that the portion flowing through one of the fuel passage sections, e.g. the outer fuel passage section, is the greatest. An advantage of a largest portion flowing through the outer fuel passage section may be that the outer fuel passage section may have a larger flow cross section, which is associated with a smaller reduction in the passage height (due to the larger diameter). In this way, a very low channel height, which may possibly be associated with production-related problems, can be avoided.For an optimized flow field within the combustion chamber, two air channels which are radially offset from one another, for example, arranged coaxially with respect to one another at least in sections, are preferably arranged radially on the outside, in particular annularly, around the fuel channel, within which air channels a swirl generator (generation of a flow with a superimposed tangential velocity component) is preferably arranged in each case.In this context, the two air-guiding ducts preferably each have a downstream end section towards the opening into the combustion chamber, which end section is aligned axially radially in the direction of the nozzle longitudinal axis. The end sections can be oriented at least substantially parallel to one another and / or to at least one end section of the fuel duct, for example.The twisted air flow conducted through the two outer air ducts is directed radially inward by means of the axially radially oriented end sections, wherein it meets the air flow from the first air duct at the downstream end of the film-laying surface. In this manner, the fuel stream at the trailing edge at the downstream end of the film-forming surface is embedded in two air streams and is broken up thereby into fine droplets. In the embodiment with three air ducts and two air ducts arranged radially outside the fuel duct, the radially outermost air duct, also referred to as "dome air passage", likewise subjects the air flow to a swirl and initially directs it radially inward due to the axially radially oriented end section. This air flow causes and / or enhances the effect that the flow of air (of the first and second air ducts) and fuel (droplets) upon flowing into the combustion chamber, as a result of its angular momentum, a pressure gradient is established in such a way that the air-fuel flow is drawn radially outwards and thus a swirling hollow cone spray is generated.The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawings. The following are shown: FIGS. 1A, 1B, 1C show a part of a nozzle for supplying air and liquid fuel into a combustion chamber schematically in longitudinal section according to the prior art, with a first air duct, a fuel duct and with two outer air ducts (FIG. 1A ) and without illustration of the outer air ducts (FIGS. 1B, 1C ), FIGS. 2A, 2B show a part of a nozzle according to the invention for supplying air and liquid fuel into a combustion chamber schematically in longitudinal section, with a fuel duct, for example comprising three fuel duct sections connected fluidically parallel to one another, with three radially offset surface sections of a film-laying surface arranged axially one behind the other, FIGS. 3A, 3B show a part of the nozzle according to the invention schematically in longitudinal section in a further embodiment variant, with axially radially inclined surface sections of the film-laying surface, and FIG. 4 shows a part of the nozzle according to the invention schematically in longitudinal section in a further embodiment variant, with surface sections of the film-laying surface aligned radially at the same height and exclusively axially and one behind the other.FIG. 1A schematically shows a part of a nozzle main body 10 of a nozzle for supplying air 13 and liquid fuel 17 with fuel atomization into a combustion chamber 30 of an engine of an aircraft, as known from the prior art. The liquid fuel is in particular kerosine or a kerosine-based fuel and / or a synthetic liquid fuel.The nozzle main body 10 is aligned with a main body 32 along a nozzle longitudinal axis L. A first air duct 14 running at least in sections on the nozzle longitudinal axis L is arranged circumferentially surrounded by the base body 32. Preferably, a swirl generator for imparting swirl (velocity component in the circumferential direction) to the air portion flowing through during operation is arranged in the first air duct 14 (not shown here). The first air duct 14 opens into the combustion chamber 30 in particular with only an axial directional component.Radially circumferentially around the first air passage 14, the nozzle main body 10 has a fuel passage 16. The radial inner wall of the fuel channel 16 is formed by the base body 32, and the radial outer wall is formed by an outer fuel channel wall 283. The fuel channel 16 has an axial section 16 aaligned coaxially to the nozzle longitudinal axis L and subsequently an end section 16 b, which is oriented axially radially inward, in the direction of the nozzle longitudinal axis L and on the downstream side and opens into a fuel outlet opening 24. The fuel outlet opening 24 is aligned substantially axially with respect to the nozzle longitudinal axis L. Furthermore, the fuel outlet opening 24 is arranged, for example, radially offset outwards with respect to the inner wall of the first air duct 14. An inward offset would also be possible.Downstream of the fuel outlet opening 24, the same is followed by a film-forming surface 20, at the downstream end of which a trailing edge 22 is arranged. The film-laying surface 20 has a smaller radial orientation than the end section 16 b. The film-laying surface 20 is here, for example, aligned exclusively axially with respect to the nozzle longitudinal axis L, so that it forms a circumferential cylinder section aligned about the nozzle longitudinal axis L. An axial-radial alignment with a smaller radial than axial direction component is also possible, wherein a conical peripheral surface, which narrows in the flow direction, is produced in a circumferential manner.The fuel outlet opening 24 and the film-laying surface 20 are arranged in particular at the downstream end of the first air duct 14, for overflowing with air flowing through the first air duct 14.Radially annularly encircling the fuel duct 16, the nozzle main body 10 preferably has two air ducts arranged radially offset from one another, a second air duct 121 and a radially outermost, third air duct 122. Swirl generators 123, 124 are preferably arranged in the air ducts 121, 122. The air ducts 121, 122 each have a downstream end section to the opening into the combustion chamber 30, which is oriented axially radially inward, in the direction of the nozzle longitudinal axis L. In the present case, the end sections run, for example, substantially parallel to one another and / or to the end section 16 bof the fuel duct 16.During operation, air 13 is conducted through the air channels 14, 121, 122, which are present here by way of example. The liquid fuel 17 is guided through the at least one fuel duct 16 to the preferably annular fuel outlet opening 24 and flows, in particular directly downstream, of the fuel outlet opening 24 onto the film-laying surface 20. Shear stresses applied by the air 13 induce (small scale) flow instabilities in the fuel flow and tear individual fuel droplets out of the film.The twisted air flow flowing through the second air duct 121 and third air duct 122 is directed radially inward by means of the axially radially oriented end sections, wherein it meets the air flow from the first air duct 14 at the downstream end of the film-laying surface 20. In this manner, the fuel stream at the trailing edge 22 at the end of the film-forming surface 20 is embedded in two air streams and is broken up thereby into fine droplets. In the embodiment with three air ducts, the radially outermost, third air duct 122, also referred to as "dome air passage", likewise subjects the air flow to a swirl and initially directs it radially inward due to the axially radially oriented end section. This air flow brings about a pressure gradient by means of its angular momentum in such a way that the stream of air 13 and fuel 17 (droplets) is drawn radially outwards when it flows into the combustion chamber 30, and a swirling hollow cone spray is generated.Studies of the fuel flow at the fuel outlet opening 24 have shown that the fuel 17 flowing out of the film-laying surface 20 is subject to fluctuations. These fluctuations consist, on the one hand, in the fact that, as a result of the interaction with the sweeping air, fuel waves can build up at the fuel outlet opening 24 upstream of the film-laying surface 20, which waves travel downstream and collapse over the film-laying surface 20 (illustrated schematically in FIG. 1B ). In this way, large current filaments can form downstream of the trailing edge 22, which break down further downstream into relatively large droplets. On the other hand, there are fluctuations in the wavy loading of the film-laying surface 20 with fuel 17 emerging from the fuel outlet opening 24, as a result of which fuel mass flows of different sizes leave the film-laying surface 20 (in a partially periodically repeated sequence), shown in FIG. 1C by the representation of a time t0 (gray-filled surface) and a time t1 (dashed line). The time interval between the illustrated times is in the order of about 1 / 1000 s to 1 / 10,000 s.As a result of the fluctuations in the fuel mass flow and the resulting droplet size distribution, pressure fluctuations / thermoacoustics which are related to the flame dynamics can occur and the pollutant formation within the combustion chamber 30 can be adversely influenced.In order to avoid such fluctuations of the fuel mass flow in the event of outflows from the film-laying surface 20, a nozzle is proposed, as is schematically illustrated in a longitudinal section by way of example in FIGS. 2A and 2B. The part shown in FIG. 2A corresponds to the part of the nozzle shown in FIG. 1A, the part shown in FIG. 2B substantially shows the fuel channel 16 with a part of the base body 32 and the outer fuel channel wall 283, as well as the film-laying surface 20 and the trailing edge 22 (similar to FIGS. 1B and 1C ). In contrast to the nozzle shown in FIGS. 1A, 1B and 1C, the fuel channel 16 in the proposed nozzle has, upstream of the film-laying surface 20, at least two fuel channel sections, here, for example, three, which are arranged fluidically parallel to one another and preferably radially offset from one another, a radially inner fuel channel section 161, a radially middle fuel channel section 162 and a radially outer fuel channel section 163. The fuel duct sections 161, 162, 163 are in particular each annularly formed circumferentially. The division of the fuel channel 16 into the fuel channel sections 161, 162, 163 takes place in particular within the downstream second half or in the downstream last third of the nozzle main body 10.The remaining configuration of the nozzle, relating to the air ducts 14, 121 and 122, corresponds in the present case by way of example to the configuration as shown in FIG. 1A.The fuel channel sections 161, 162, 163 open downstream in each case into a fuel outlet opening, which in particular extends annularly, a first outlet opening 241, a second outlet opening 242 and a third outlet opening 243. The outlet openings 241, 242 and 243 are arranged axially offset from one another (one behind the other) with respect to the nozzle longitudinal axis L. The axial extent of the individual outlet openings 241, 242, 243 is significantly smaller than in the case of the individual outlet opening 24 according to the prior art and is, for example, 0.2 mm to 0.3 mm (prior art: for example 0.5 mm to 0.7 mm).Downstream of the respective outlet openings 241, 242, 243, in each case one surface section of the film-laying surface 20 is arranged, i.e. a first surface section 201 (directly) downstream of the first outlet opening 241, a second surface section 202 (directly) downstream of the second outlet opening 242 and a third surface section 203 (directly) downstream of the second outlet opening 243. The surface sections 201, 202, 203 are therefore arranged offset axially with respect to one another (one behind the other) in the flow direction without overlap. The surface lengths of the surface sections 201, 202, 203 correspond, for example, to a factor in the range from 2 to 10, in particular in the range from 3 to 5 times the length dimension of the fuel outlet opening 241, 242, 243 arranged upstream on the respective surface section, which length dimension is arranged parallel to the nozzle axis.This results in a total of a film-laying surface 20 that is significantly longer axially compared to the prior art (e.g., longer by a factor of 1.5 to 4) and extends downstream of the first outlet opening 241 as far as the trailing edge 22, wherein it is interrupted by at least one further outlet opening, in the present case, for example, the two outlet openings 242, 243, and is divided axially into the surface sections 201, 202, and 203. The outlet openings 241, 242, 243 open onto and / or into the film-laying surface 20.By applying the fuel mass flow by means of the plurality of fuel duct sections 161, 162, 163 and outlet openings 241, 242, 243, the mass flow per outlet opening 241, 242, 243 is significantly reduced. This reduces or prevents accumulation of fuel 17 at a single orifice. Wave formation or fluctuations in the fuel mass flow are significantly reduced or avoided.The individual fuel duct sections 161, 162, 163 each have an axially oriented axial section 161 a, 162 a, 163 aarranged upstream, for example exclusively axially. As shown in FIG. 2B, at least one swirl generator 181, 182, 183 for establishing and / or maintaining a circumferential swirl are preferably arranged in each of the axial sections 161 a, 162 a, 163 a.Immediately downstream of the axial sections 161 a, 162 a, 163 a, a respective axially radially inwardly oriented downstream end section 161 b, 162 b, 163 bconnects, which ends in the respective outlet opening 241, 242, 243 of the fuel duct sections 161, 162, 163.Arranged between the individual fuel duct sections 161, 162, 163 as fuel guide walls are two fuel guide elements which are correspondingly shaped cylindrically conically, a first fuel guide element 282 arranged radially further outwards and a second fuel guide element 281 offset radially inwards in relation thereto. The swirl generators 181, 182, 183 serve simultaneously as spacers and joining elements between the individual components of the nozzle main body 10. The cylindrical-conical elements carry, on the inside and / or outside of the cylindrical section, the swirl generators 181, 182, 183, respectively, which form the points of contact with the adjacent components. Connection to the nozzle main body 10 as an entire component can be made by known methods, for example, by welding and / or soldering techniques.At the upstream ends of the fuel guide members 281, 282, acute-angle flow splitters 261, 262 are disposed, respectively. The flow dividers 261, 262 or the fuel guide elements 281, 282 are also arranged offset axially with respect to one another in addition to the radial offset, so that an axially radial flow direction which is favorable in terms of the pressure loss is generated during operation.The flow dividers 261, 262 are arranged one behind the other in the flow direction in order to divide the total fuel flow supplied by means of the fuel duct 16 into the fuel duct sections 161, 162, 163.Upstream of the first, radially outer flow divider 261, the fuel channel 16 has an overall section 164 for conducting the entire overall fuel flow supplied by means of the fuel channel 16. The overall section 164 is here aligned in particular exclusively axially. Downstream of the first flow divider 261, there is connected on the one hand the axial section 163 aof the radially outer fuel duct section 163, which runs at least substantially the same radial position as the overall section 164. The first flow divider 261 is adjoined by an axially radially oriented transition section 165 (cf. FIG. 2A ), which transfers the fuel mass flow remaining from the total mass flow to the second flow divider 262, which is axially offset in the direction of the combustion chamber and is radially further inside. At the second flow divider 262, the remaining fuel mass flow is again divided between the axial section 162 aof the middle fuel duct section 162 and the transfer section 165, which transfers the remaining fuel mass flow finally into the inner axial section 161 a.The flow cross sections of the fuel duct sections 161, 162, 163 are designed, for example, in such a way that, during operation, the total fuel flow is divided into at least substantially identical portions. Accordingly, due to larger radii of the fuel passage sections 162, 163, the gap heights decrease radially outward. The outlet openings 241, 242, 243 have essentially the same axial dimensions because of their arrangement in a similar or identical radial position. Alternatively, for example, the configuration may be such that a larger proportion of fuel flows through the outer fuel passage portion 163. In this way, very small gap heights can be avoided, which can result in advantages in production.In the embodiment variant shown in FIGS. 2A and 2B, the individual surface sections 201, 202, 203 are arranged slightly radially offset in stages with respect to one another, for example. In this case, the first surface section 201 located furthest upstream is offset slightly radially outwards with respect to the inner wall of the first air duct 14 arranged upstream thereof. The surface sections 202, 203 arranged axially downstream are, in contrast, each offset further radially outwards. The offset corresponds approximately to the increase in the film thickness of fuel 17 at each outlet opening 241, 242, 243, for example.FIGS. 3A and 3B each show a part of the nozzle according to the invention schematically in longitudinal section in a further embodiment variant. In this case, the surface sections 201, 202, 203 are, for example, aligned with an axial-radial direction component, i.e. arranged set (inclined), e.g. without radial offset of the individual surface sections 201, 202, 203. The slope is formed against the air flow direction, wherein in operation the interaction of the fuel film with the air flow is influenced. The air flow flowing through the first air duct 14 thus impinges on the film-laying surface 20 at a slight angle.The exact arrangements and configurations of the surface sections 201, 202, 203 can be combined with one another in different ways, wherein in particular the variables "surface lengths", "radial positions" and / or "alignment (angle) with respect to the nozzle longitudinal axis L" form degrees of freedom in the design. For example, a combination of the adjusted face orientation shown in FIGS. 3A and 3B with the radial offset shown in FIGS. 2A and 2B is possible.FIG. 4 shows a part of the nozzle according to the invention schematically in longitudinal section, wherein the surface sections 201, 202, 203 are aligned exclusively axially (parallel to the nozzle longitudinal axis L) and are arranged at the same radial position (height) with respect to the nozzle longitudinal axis L without radial offset with respect to one another. The radial position corresponds to that of the inner wall of the first air duct 14 upstream of the first outlet opening 241.List of reference characters10 Nozzle main body 121 Second air duct 122 Third air duct 123 Inner swirl generator 124 Outer swirl generator 13 Air 14 First air duct 16 Fuel duct 16 aAxial section 16 bEnd section 161 Inner fuel duct section 161 aAxial section 161 bEnd section 162 Middle fuel duct section 162 aAxial section 162 bEnd section 163 Outer fuel duct section 163 aAxial section 163 bEnd section 164 Overall section 165 Transition section 17 Fuel 18 Swirl generator 181 First swirl generator 182 Second swirl generator 183 Third swirl generator 20 Film-laying surface 201 First surface section 202 Second surface section 203 Third surface section 22 Trailing edge 24 Fuel outlet opening 241 First outlet opening 242 Second outlet opening 243 Third outlet opening 261 First flow divider 262 Second flow divider 281 Second fuel guide element 282 First fuel guide element 283 Outer fuel duct wall 30 Combustion chamber 32 Basic body L Nozzle longitudinal axis t0 Time t1 TimeReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2017 218 529 A1

[0002] U.S. Pat. No. 9,423,137 B2

[0003] US 2014 / 0241871 A1

[0004] US 2020 / 0141582 A1

[0004] US 2022 / 0099290 A1

[0004] US 2016 / 0047315 A1

[0004] US 2010 / 0229556 A1

[0004]

Claims

Nozzle for supplying air and liquid fuel into a combustion chamber (30), in particular of an engine of an aircraft, having a nozzle main body (10) which is aligned along a nozzle longitudinal axis (L) and in which are arranged: - at least one first air duct (14) which runs on and / or around the nozzle longitudinal axis (L), - at least one fuel duct (16) which is arranged radially on the outside, in particular annularly encircling, around the first air duct (14), and - at least one second air duct (121) which is arranged radially on the outside, in particular annularly encircling, around the fuel duct (16), wherein the fuel duct (16) opens with a downstream outflow edge (22) with an outlet opening (24, 241, 242, 243) at an at least substantially axially aligned film-laying surface (20), characterized in that the fuel duct (16) upstream of the film-laying surface (20) at least two flow-connected parallel to one another, in terms of flow technology, In particular, the film-laying surface (20) has fuel channel sections (161, 162, 163) which run annularly around the nozzle longitudinal axis (L), wherein in each case one outlet opening (241, 242, 243) is arranged at the downstream ends of the fuel channel sections (161, 162, 163), and in each case one surface section (201, 202, 203) of the film-laying surface (20) is arranged downstream of the latter.Nozzle according to Claim 1, characterized in that the at least two surface sections (201, 202, 203) are arranged axially one behind the other and, for example, radially offset with respect to one another.Nozzle according to Claim 1 or 2, characterized in that the at least two surface sections (201, 202, 203) each have a surface length in the direction of the nozzle longitudinal axis (L) which corresponds to between a factor of 2 and a factor of 10, in particular between a factor of 3 and a factor of 5, of the axial dimension of the outlet opening (241, 242, 243) arranged upstream on the respective surface section (201, 202, 203).Nozzle according to one of the preceding claims, characterized in that the at least two fuel duct sections (161, 162, 163) each have an axial section (161a, 162a, 163a) and / or a downstream end section (161b, 162b, 163b), which is arranged in particular downstream and adjoins the latter in the axial-radial direction inwards and is aligned with the nozzle longitudinal axis (L).Nozzle according to Claim 4, characterized in that the surface sections (201, 202, 203) have a smaller radial directional component in their orientation than the end sections (161b, 162b, 163b).Nozzle according to one of the preceding claims, characterized in that at least one swirl generator (181, 182, 183) is arranged in at least one, preferably in each, of the fuel duct sections (161, 162, 163), wherein preferably the at least one swirl generator (181, 182, 183) is arranged, optionally in each case, in the axial section (161a, 162a, 163a).Nozzle according to one of the preceding claims, characterized in that the fuel duct (16) is designed in such a way that the division of a total fuel flow supplied by means of the fuel duct (16) into partial fuel flows within the fuel duct sections (161, 162, 163) within the nozzle main body (10) and / or in the flow direction takes place successively in stages.Nozzle according to one of the preceding claims, characterized in that the at least two fuel duct sections (161, 162, 163) are separated from one another by means of at least one fuel guide wall, in particular a fuel guide element (281, 282), at the upstream end of which a flow divider (261, 262), in particular an acute angle, is optionally arranged in each case.Nozzle according to Claim 8, characterized in that, in the presence of a plurality of fuel guide walls, the upstream ends, with the flow splitters (261, 262), are arranged offset axially and / or radially with respect to one another.Nozzle according to Claim 8 or 9, characterized in that the fuel duct (16) has, upstream of a first flow splitter (261), an, in particular exclusively, axially aligned overall section (164) for conducting the entire total fuel flow fed by means of the fuel duct (16), and / or in that, downstream of the first flow splitter (261), an outer fuel duct section (163), in particular its axial section (163a), is arranged, and / or an, in particular axially radially aligned, transfer section (165) for transferring the fuel mass flow remaining from the total mass flow to a second flow splitter (262) and / or an axial section (162) of a, e.g. middle or inner, fuel duct section (162, 161) arranged radially further inwards.Nozzle according to one of the preceding claims, characterized in that the fuel duct sections (161, 162, 163), in particular their flow cross sections, are designed in such a way that, during operation, the total fuel flow is divided into at least substantially identical portions, or in such a way that the portion flowing through one of the fuel duct sections (161, 162, 163), for example the outer fuel duct section (163), is the greatest.Nozzle according to one of the preceding claims, characterized in that arranged radially on the outside, in particular circumferentially in a ring shape, around the fuel duct (16) are two air ducts (121, 122) which are offset radially with respect to one another, for example arranged coaxially with respect to one another at least in sections, within which ducts a swirl generator (123, 124) is preferably arranged in each case.Nozzle according to Claim 12, characterized in that the two air-guiding ducts (121, 122) each have a downstream end section towards the orifice into the combustion chamber (30), which end section is aligned axially radially in the direction of the nozzle longitudinal axis (L).An engine having at least one nozzle according to any preceding claim.

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