Nozzle assembly with a central fuel supply and at least one air channel

Abstract

The invention relates to a nozzle assembly for a combustor (103) of an engine (T), comprising at least one nozzle (D) for injecting fuel into a combustion chamber (1030) of the combustor (103), wherein the nozzle (D) comprises a nozzle main body (DR) extending along a nozzle longitudinal axis (L) and having a nozzle head (DK), and a nozzle holder (DH) connected to the nozzle main body (DR) and having at least one fuel supply line (1). The nozzle main body (DR) comprises a central fuel pipe (3) extending along the nozzle longitudinal axis (L) and at least two radially spaced-apart air guide channels (4, 5) on the nozzle head with a respective at least one air outlet opening.

Description

[0001]

[0002] Nozzle assembly with central fuel supply and at least one air duct

[0003] Description

[0004] The invention relates to a nozzle assembly for a combustion chamber of an engine with at least one nozzle for injecting gaseous fuel, in particular hydrogen, into a combustion chamber of the combustion chamber, wherein the nozzle comprises a nozzle main body with a nozzle head extending along a nozzle longitudinal axis and a nozzle holder connected to the nozzle main body and having at least one fuel supply line.

[0005] Nozzle assemblies for engine combustion chambers are widely known in various forms. The focus of conventional nozzles of such nozzle assemblies to date has been the injection of fuels, in which, especially in the case of gaseous fuels, the fuel is mixed with air within the nozzle to create a combustible fuel-air mixture immediately downstream of the nozzle end. In applications using liquid fuels, such as kerosene or diesel, however, the air flow through the nozzle is often used to atomize (or at least assist in atomizing) the fuels into sprays within the nozzle or directly downstream of it. Typically, in both of these approaches, the air to be mixed is already wired within the nozzle, creating a swirling fuel-air flow with turbulence and recirculation downstream of the nozzle end, which is considered beneficial for combustion.

[0006] Such various nozzle assemblies are shown in various designs in the documents US 4 842 509 A, DE 10 62 873 A, GB 2 593 123 A, US 5 117 637 A, US 4 483 138 A, DE 103 14 941 A1, US 9 488 108 B2 and also in US 5 636 511 A. For example, in the latter, a coaxial ignition unit with a ceramic body is arranged in a central tube, onto which a hardened platinum wire is wound in the form of a coil. Fuel and air are mixed in the central tube, with openings for supplying air being introduced into the wall of the central tube around the ignition unit. This air is supplied via an annular channel formed by an outer coaxial tube.

[0007] In recent times, there has been an increasing development of concepts for aircraft engines in which the engine is operated partially or completely with hydrogen or other gaseous injected fuels, as is envisaged, for example, in US 4,713,938 A1 for a gas turbine for power generation. However, if an engine is to be operated with hydrogen instead of kerosene or diesel, for example, while maintaining as similar a design as possible, a different injection system is necessary because the fuel is introduced into the combustion chamber in gaseous form and, in the case of hydrogen, for example, also has significantly shorter ignition delay times and higher flame speeds. Against this background, the nozzle assembly of claim 1 is proposed, which in particular comprises a nozzle for injecting hydrogen into a combustion chamber of an engine-side combustion chamber, but which is also suitable for injecting other fuels, in particular gaseous fuels.

[0008] A proposed nozzle assembly comprises a nozzle with a nozzle main body that includes a central fuel tube extending along the nozzle's longitudinal axis. Furthermore, at least two radially spaced air guide channels, each with at least one air outlet opening, are provided on the nozzle head, so that a central fuel outlet opening of the fuel tube is formed at the nozzle end, and the at least two air outlet openings of the two air guide channels are formed radially further outward.

[0009] Air can be introduced into the combustion chamber via air ducts to mix with the fuel discharged from the fuel outlet. Thus, at least two air ducts are provided on the nozzle head, located radially further outward relative to the inner or central fuel pipe.

[0010] The fuel pipe can protrude axially with its fuel outlet opening relative to the air outlet openings of the air guide channels, relative to the longitudinal axis of the nozzle. The fuel outlet opening is thus located at least as far or further downstream than the air outlet openings of the air guide channels in a flow direction defined by the fuel pipe, along which the fuel is guided within the main nozzle body. In particular, in this context it can be provided that the fuel outlet opening is arranged furthest downstream, i.e. each air outlet opening is arranged axially set back from the fuel outlet opening of the fuel pipe relative to the longitudinal axis of the nozzle. This allows the fuel to be injected further downstream into the combustion chamber than air via the radially outer air guide channels.This helps ensure that the heat release due to combustion of the fuel-air mixture downstream of the nozzle does not place a critical thermal load on the nozzle.

[0011] Furthermore, the air flowing in via the at least two air ducts creates an air-rich zone in a front area of ​​the combustion chamber around the nozzle end (a so-called outer recirculation zone). This allows the nozzle and a combustion chamber wall surrounding the nozzle to be thermally protected from the combustion zone. Air outlet openings of the various air ducts can each be designed as an annular gap, in particular as a circular gap.

[0012] In principle, the at least two air ducts of the nozzle head, which are spaced apart from one another radially, can provide air flows with different air quantities, different swirls and, in particular, also different flow velocities. For this purpose, an outer air outlet opening of a radially outermost air duct of the at least two air ducts can have a larger cross-sectional area than an inner air outlet opening of an inner air duct of the at least two air ducts, which runs on the nozzle head between the radially outermost air duct and a section of the fuel pipe. For example, it is provided that an outer air outlet opening of a radially outermost air duct of the at least two air ducts has an area that is at least 2, 4 or 6 times larger (during operation of the combustion chamber orof the engine through which air flows) than an inner air outlet opening of an inner air duct of the at least two air ducts.

[0013] The inner air guide channel is provided on the nozzle head between the radially outermost air guide channel and a section of the fuel pipe. For example, an air flow with a comparatively high axial impulse and with less swirl than the outer air guide channel or no swirl at all is provided via the radially inner air guide channel. In this context, it is therefore provided that the radially inner air guide channel is designed and provided to provide a non-swirl-laden air flow into the combustion chamber. Alternatively, the radially inner air guide channel can be designed and provided to provide a swirl-laden air flow into the combustion chamber, but the swirl of the air flow from the inner air guide channel is set to be lower than the swirl of the air flow that flows into the combustion chamber via the radially outer or outermost air guide channel (during operation of the combustion chamber).It is therefore not necessary, but possible, to generate an air flow with imposed swirl via the radially inner air duct. Imparting swirl can be advantageous, for example, with regard to the stability of the burner, the flame shape and / or position, the pollutant formation rate, and the thermal load on the nozzle. In particular, the air ducts can then be designed such that the air flow from the inner air duct has a swirl that is a defined amount, e.g., more than 50% or more than 60% lower than the swirl of the air flow from the outer air duct. In this way, the air flow from the radially inner air duct continues to be primarily tangential to the inflow of fuel from the fuel pipe, and at least with a larger axial component than the air flow from the outer air duct.The air flow from the radially inner air duct adjacent to the fuel pipe thus supports a shift of the zones of chemical combustion reactions as far as possible into the combustion chamber.

[0014] In one design variant, the radially outermost air duct with the larger cross-section is therefore primarily intended to provide a swirling air flow into the combustion chamber. This can generate an air flow at the nozzle end that envelops the fuel flow, draws it radially, and thus creates a recirculation zone downstream of the nozzle end in which air and fuel mix, forming a swirl-stabilized, recirculating combustion zone. The air from the air ducts enveloping the combustion zone also provides an air-rich zone around the nozzle in a front area of ​​the combustion chamber (a so-called outer recirculation zone). This can thermally protect the nozzle and a combustion chamber wall from the combustion zone.

[0015] For the formation of an effective recirculation zone, it can also be advantageous if, as explained, the air flow introduced into the combustion chamber via the outermost air duct exhibits a swirl, while the air flow from the inner air duct is not subject to swirl, or if the air flow introduced into the combustion chamber via the outermost air duct exhibits at least a greater swirl than the air flow from the inner air duct. For example, one or more axial swirlers or radial swirlers are provided for this purpose in at least one radially outermost air duct of the at least two air ducts.

[0016] In order to provide a sufficient amount of air, in particular for an outer recirculation zone as explained above, via the nozzle, one or more radially inward-facing inlet lips can be provided at least on a radially outermost air guide channel of the at least two air guide channels in order to guide air into the radially outermost air guide channel and optionally also into another air guide channel located radially further inwards. When the nozzle assembly is installed as intended, the one or more inlet lips thus also lead, for example, to air coming from a compressor stage and guided around the main nozzle body being guided radially inwards into the radially outermost air guide channel and optionally also into another air guide channel located radially further inwards.The use of inlet lips for one or more air ducts can be particularly advantageous for a head region of the nozzle, which is comparatively thick and may therefore initially hinder the axial flow of a sufficiently large amount of air into the air duct(s). In one design variant, a local narrowing of the inner air duct towards its air outlet opening can be provided. Sections of the inner and outer (duct) walls bordering the inner air duct and lying opposite one another thus approach one another in the area of ​​the air outlet opening. This allows the inner air duct to narrow, for example, in the shape of a nozzle, whereby the outlet velocity of the incoming air can be increased. In addition, such a narrowing can also be used to deflect the air flow radially inwards, i.e. in the direction of the longitudinal axis L of the nozzle.

[0017] A centrally arranged flow body can be provided within the central fuel pipe, along the outer surface of which fuel supplied to the fuel pipe can flow toward a fuel outlet opening of the fuel pipe, through which the fuel can be introduced into the combustion chamber. Such a central flow body can be provided in combination with the at least two air guide channels. In principle, however, the use of such a central flow body can also be advantageous in other designs of a nozzle head with a central fuel pipe, e.g., in combination with only one surrounding coaxial air guide channel.

[0018] Fuel can flow axially around the centrally arranged flow body, thus serving to even out the fuel flow within the fuel pipe and / or to influence the direction of fuel flow at the fuel outlet. Consequently, fuel supplied to the nozzle via at least one fuel supply line in a nozzle holder can be guided within the main nozzle body to the fuel outlet of the fuel pipe, which is co-defined by one end of the flow body. With the aid of the (downstream) end of the flow body, the fuel can be injected into the combustion chamber, in particular with a radially outward-facing flow component, and / or can positively influence a flow field in the combustion chamber.In principle, a flow body provided within the fuel pipe can extend with one end to the nozzle end, and in particular to the fuel outlet opening. For example, the flow body at the nozzle end can protrude axially relative to a radially outer edge of the fuel outlet opening, i.e., protrude at least slightly axially beyond the edge of the fuel outlet opening. For an axially protruding flow body, for example, it is provided that the flow body protrudes by an amount equal to 5% or 10% of the diameter of the central fuel pipe.

[0019] In combination with the flow body, an advantageous embodiment in conjunction with the central injection of gaseous fuel, namely hydrogen, into the combustion chamber consists in integrating a spark plug into the fuel pipe, particularly into the flow body, with its front ignition section facing the combustion chamber. In this way, the use of a small, advantageous spark plug that can be operated with low energy consumption allows for fine adjustment of the fuel flow introduced into the combustion chamber to achieve optimal ignition conditions.

[0020] In an advantageous further embodiment, the spark plug is accommodated in a central cavity of the flow body. This results in a defined, precise installation, whereby the cavity in the flow body can be formed, for example, by a central bore formed coaxially with the longitudinal axis, e.g., a blind hole open at the front.

[0021] It is also advantageous that a cable connection for electrically controlling the spark plug is routed through the flow body, for example, a feedthrough installed on the rear side of the cavity, and optionally a support element, in particular a support strut, of a support structure holding the flow body in the fuel pipe, as well as through the nozzle holder. The spark plug installation and the cable routing are designed to be leak-tight.

[0022] For an optimized adjustment of the fuel flow into the combustion chamber and the ignition conditions, it is advantageously provided that the flow body which is blunt towards the combustion chamber, the area of ​​the fuel outlet opening and the area of ​​at least one air outlet opening of at least one air guide channel, in particular arranged in the nozzle body, are designed and coordinated with one another in such a way that the air supply and the gas supply into the combustion chamber lead to a recirculation of the gas-air mixture towards the ignition section of the spark plug.

[0023] The installation of the spark plug in the specified combination with the flow body is based on the consideration that the central injection of the gaseous fuel, particularly hydrogen, ensures that only a small amount of the gas-air mixture is distributed outwards towards the combustion chamber wall, particularly during operating conditions with low air mass flow and low air velocities, e.g., during engine start-up. Conventionally, however, the spark plug for igniting the gas-air mixture is usually positioned on the combustion chamber wall. This makes ignition only possible when a suitable amount of gas-air mixture is present. This can result in a large amount of ignitable mixture already being present in the combustion chamber before ignition occurs. This can lead to a detonation-like ignition.The solution according to the invention specified here results in an advantageous integration of the ignition device for optimal ignition conditions in the aforementioned design of the nozzle assembly with central injection of the gaseous fuel, in particular hydrogen.

[0024] One end of the flow body can specify a flow direction for the fuel to be injected into the combustion chamber. For example, the flow body can have a guide element at its end for this purpose, via which fuel escaping from the fuel outlet opening is guided radially outwards relative to the longitudinal axis of the nozzle. For example, the guide element at the end of the flow body is formed by a radial widening of the flow body. The fuel injection into the combustion chamber with a radially outward-facing flow component can influence the properties, such as the shape and size, of the flow field of a recirculation zone created downstream of the nozzle end. This can be advantageous, especially with gaseous fuel and in particular hydrogen, with regard to flame stability and comparatively low combustion temperatures directly in the near field of the nozzle.

[0025] Furthermore, a targeted acceleration of the fuel flow into the combustion chamber can be achieved via a constriction at the end of the fuel pipe at the fuel outlet opening, which is realized with the end of the flow body facing the combustion chamber.

[0026] In principle, the flow body can be cone-shaped or tapered.

[0027] Alternatively or additionally, the flow body is symmetrical, in particular rotationally symmetrical, to the nozzle's longitudinal axis and / or with a blunt, centrally located end facing the combustion chamber. A blunt, centrally located end at one end of the flow body can, for example, support the formation of an inner recirculation zone with a comparatively high fuel concentration during operation of the combustion chamber or engine. Such an inner recirculation zone may be associated with low combustion temperatures in the near field of the nozzle and thus immediately downstream of the nozzle end. The blunt end can, in principle—depending on the desired flow conditions—be essentially flat, (slightly) convex, or (slightly) concave.

[0028] In principle, the flow body can have an upstream and optionally aerodynamically shaped, convexly curved end that is axially spaced from an end wall of the nozzle or a rear wall of the fuel pipe. In principle, however, another aerodynamically favorable shape can also be provided for the upstream end. For example, the end can be hemispherical, conical (optionally with a blunt or rounded cone tip), ogive-shaped, or ovoid-shaped. In particular, depending on the design of the supply reservoir, the flow body can also be connected to an end wall of the nozzle or a rear wall of the fuel pipe in embodiment variants of the proposed solution. In this case, the flow body then extends along the longitudinal axis of the nozzle away from the end wall or the rear wall and is thus not axially spaced from the end wall or the rear wall.While an axially spaced flow body has an upstream end within the fuel pipe, which is exposed to the axial flow of fuel, this is not the case with a flow body connected to the end wall or rear wall. Depending on the design and boundary conditions, one or the other shape of the flow body may be advantageous, for example, with regard to the thickness of the nozzle main body that can be achieved in a head region of the nozzle main body.

[0029] If the flow body is not connected to an end wall of the nozzle or a rear wall of the fuel pipe and runs centrally within the fuel pipe along the nozzle's longitudinal axis up to the fuel outlet opening, the flow body typically extends over a large part of the length of the nozzle main body comprising the fuel pipe, measured along the nozzle's longitudinal axis, e.g., over at least 85% of this length. In one embodiment, two flow bodies can also be present within the fuel pipe, axially spaced from one another with respect to the nozzle's longitudinal axis. In such a embodiment, a pipe section of the fuel pipe through which fuel can flow across its entire cross-section is therefore located centrally between the two flow bodies.For example, a first upstream flow body is cone-shaped, while a further flow body provided downstream in the region of the fuel outlet opening is conical or otherwise aerodynamically favorable - e.g. hemispherical, conical (optionally with a blunt or rounded cone tip), ogive-shaped or ovoid-shaped.

[0030] The flow body can comprise several (at least two) protruding sections on its outer surface, around which the flow axially passes during operation of the combustion chamber. These protruding sections can serve, on the one hand, to intensify heat transfer between the material of the flow body, which is typically made of metal, and the cooler fuel - particularly during operation of the combustion chamber. If the flow body extends as far as the fuel outlet opening, it is exposed to comparatively high temperatures at least on one side facing the combustion chamber, so that the injected fuel in the region of the flow body can also be used for cooling, particularly if this is hydrogen to be injected. The sections protruding on the outer surface can also be used in a targeted manner to influence the fuel flow within the fuel pipe.For example, the protruding sections are formed by ribs, webs, pins, tenons or fins. The protruding sections can be provided evenly distributed on the axially flowing outer surface. In particular, the protruding sections can be distributed over the entire outer surface, or only in a limited area of ​​the surface (e.g. in the area of ​​the fuel outlet opening). In a possible further development, the protruding sections are arranged on the outer surface in such a way that any swirl already deliberately imposed on the fuel flow is not counteracted or such a swirl is possibly even supported. In particular, the protruding sections can be designed and provided to locally influence the swirl and, if necessary, to increase it.For example, the sections protruding from the lateral surface are inclined and / or helical in shape.

[0031] Alternatively or additionally, the flow body can comprise several recesses on its axially flowing outer surface, for example in the form of holes and / or dents. Such structures that modify the surface of the flow body can also serve to intensify the heat transfer from the flow body to the fuel.

[0032] In principle, the end of the fuel pipe in the area of ​​the fuel outlet can be designed in various ways. Since, when using fuel with very rapid reaction kinetics, such as hydrogen, a flame in the combustion chamber is expected to anchor itself relatively close to the nozzle, it is fundamentally possible that, at certain engine operating points, an anchor point of the combustion zone is located directly at a trailing edge of the fuel pipe. The end of the fuel pipe should therefore be designed in such a way that, on the one hand, the heat release in the combustion chamber in the immediate vicinity of the end of the fuel pipe is kept to a minimum, while, on the other hand, sufficient robustness against heat input from the combustion zone is ensured.In this context, it may be advantageous, for example, to design the fuel pipe at the fuel outlet opening with an edge running around the nozzle's longitudinal axis and having a radially outwardly inclined chamfer. In a further development, the chamfer can taper to a point towards an axial end of the fuel pipe or transition to a blunt end geometry. If the chamfer tapers to a point and the edge of the fuel pipe separates the fuel flow from an air flow of the adjacent air duct, a tapered chamfer can have the advantage that the fuel flow and the air flow meet tangentially. This allows a high outflow velocity of the two flows from the nozzle to be maintained. The heat release in the area of ​​the anchor point explained above thus remains low.A disadvantage, however, is that heat introduced into the area of ​​a tapered end during combustion chamber operation cannot be dissipated sufficiently quickly through heat conduction within the fuel tube, so that the tapered end is at risk of thermal overload. Such thermal overload can, however, be counteracted, for example, by appropriate flow control, for example, by the tangential contact of fuel and air and the resulting effects on the combustion zone, specifically the flame anchor point and the local heat release at the anchor point.

[0033] If the chamfer transitions into a blunt end geometry of the fuel tube, a small "dead water zone" or a small (internal) recirculation zone may develop immediately downstream of the nozzle end, where the fuel and the incoming air can mix, resulting in a comparatively high level of heat being released locally as a result of combustion during combustion chamber operation. However, with a blunt end geometry, the heat introduced into the edge of the fuel tube can be more effectively dissipated through heat conduction, making it easier to avoid the risk of thermal overload.

[0034] In principle, the central fuel pipe can be sealed against the inflow of air. In this way, the fuel can be introduced into the combustion chamber via the fuel pipe in the nozzle, which extends centrally in the nozzle main body along the nozzle's longitudinal axis, without mixing with air. When the nozzle assembly is installed in an engine as intended, the nozzle-side fuel pipe is thus sealed against the inflow of air from a compressor stage of the engine, in particular at an upstream end of the nozzle main body. Thus, in a nozzle of a proposed nozzle assembly, no premixing of fuel and air takes place within the nozzle. This is particularly advantageous with regard to fuel to be injected in gaseous form, and in particular highly flammable hydrogen, since it can reduce the risk of flashback or premature autoignition of the fuel to be injected.In a nozzle of a proposed nozzle assembly, the fuel to be injected is initially mixed with air only downstream of the nozzle end. Within the nozzle, the fuel is not premixed with air, so the fuel initially exits the nozzle end unmixed and only mixes with (combustion or mixing) air downstream of the nozzle end.

[0035] In one embodiment, the nozzle comprises a supply reservoir connected to the fuel supply line, to which fuel can be fed from the fuel supply line and from which fuel can be fed to the fuel pipe. The supply reservoir is thus fluidically connected to both the fuel supply line and the fuel pipe, so that the fuel coming from the fuel supply line can flow into the fuel pipe via the supply reservoir. The supply reservoir is designed, for example, as a cavity in the nozzle holder or the nozzle main body, for example as a cavity with an annular cross-section, in particular a circular ring-shaped or circular cross-section. The supply reservoir can support the most uniform possible introduction of the fuel into the fuel pipe, for example by directing the fuel flow from the supply reservoir via several specifically arranged and, for example,evenly distributed through-openings. For example, the supply reservoir is provided in a region of the nozzle which is bordered by an upstream end wall relative to a flow direction defined by the fuel pipe, along which the fuel is guided within the nozzle main body to the nozzle end. When the nozzle assembly is installed as intended in an engine, such an end wall faces away from the combustion chamber. For example, such an upstream supply reservoir is then formed in a head region of the nozzle main body connected to the nozzle holder. The fuel introduced into the fuel pipe from the supply reservoir can thus be guided in the fuel pipe over a comparatively large part (more than 60%) of the length of the nozzle main body measured along the nozzle longitudinal axis to the fuel outlet opening.In this way, the fuel can be directed to the nozzle end in a targeted manner, for example by making the fuel flow more uniform, if necessary by deliberately twisting the fuel flow.

[0036] At least one through-opening, through which fuel can flow from the supply reservoir into the fuel pipe, can be configured, for example, for fuel to flow radially inward into a first pipe section of the fuel pipe. A substantially radially inward flow into the first pipe section of the fuel pipe is thus enabled via the at least one through-opening. Consequently, one or more fluid connections provided by one or more through-openings are provided between the supply reservoir and the fuel pipe, through which fluid connections fuel can flow from the supply reservoir substantially radially inward into the first pipe section and thus into the fuel pipe.

[0037] As an alternative to a substantially radial inflow of fuel from the supply reservoir into the fuel pipe, at least one through-opening can also be provided for a substantially axial inflow of fuel into a first pipe section of the fuel pipe. For example, the at least one through-opening can extend through a rear wall of the fuel pipe that runs substantially or exactly perpendicular to the nozzle's longitudinal axis and borders (delimits) the first pipe section (upstream), or through a partition wall separating the supply reservoir from the first pipe section.

[0038] As already explained at the beginning, the proposed solution is particularly suitable for the injection of different types of fuels. However, with regard to the injection of gaseous fuel, and especially hydrogen, the central fuel supply via a nozzle-side fuel pipe, protected from mixing with air, offers particular advantages.

[0039] With nozzle assemblies of the aforementioned design, an annular combustion chamber with at least one nozzle assembly, in particular also according to one of claims 9 to 14, can be advantageously constructed in a combustion chamber ring. Advantageous embodiments include the integration of a spark plug in the aforementioned manner into at least one nozzle assembly, preferably at the highest point of the combustion chamber ring, or into several nozzle assemblies, or into all nozzle assemblies.

[0040] The proposed solution also encompasses an engine with at least one variant of a proposed nozzle assembly. However, a proposed nozzle assembly can of course also be used in a (stationary) gas turbine.

[0041] The attached figures illustrate possible embodiments of the proposed solution.

[0042] Herein: Figure 1 shows a detail and in a sectional view a first embodiment variant of a nozzle of a proposed nozzle assembly with a supply reservoir designed as an annular chamber, from which fuel can flow essentially radially inwards into a central fuel pipe of a nozzle main body equipped with a longitudinally extending flow body;

[0043] Figure 2 is a schematic diagram of a modified embodiment of a proposed nozzle assembly having two axially spaced flow bodies in the fuel pipe, illustrating the achievable circulation zones downstream of the nozzle end;

[0044] Figures 3A-3B, in a view corresponding to Figure 1, each show further developments of the embodiment variant of Figure 1;

[0045] Figures 4A-4D show schematic representations of design variants of a nozzle main body connected to a nozzle holder with flow body and integrated spark plug;

[0046] Figure 5 schematic representation of a nozzle main body according to the

[0047] Variant of the embodiment shown in Figure 3B during production in an additive manufacturing process;

[0048] Figures 6A-6B show, in views corresponding to Figures 1, 3A and 3B, further embodiments of a proposed nozzle assembly, in each of which two axially spaced-apart flow bodies are provided within the central fuel pipe; Figures 7A-9B show, in individual views, different embodiments for a second flow body provided downstream (Figures 7A, 8A and 9A) and analogous designs of an end section of a single continuous flow body (Figures 7B, 8B and 9B) for the fuel pipe;

[0049] Figures 10A-10B show various views of a second flow body according to the embodiments of Figures 6A and 6B, on whose outer surface several depressions are formed;

[0050] Figure 11 shows an end section of a continuous flow body according to Figures 1, 3A and 3B with recesses;

[0051] Figure 12 shows a sectional view of a nozzle main body with nozzle head according to the previous figures without a flow body provided within the central fuel pipe

[0052] Figure 13 shows a further development of the embodiment variant of Figure 12 with a radial swirler in the outermost air guide channel of the nozzle head;

[0053] Figure 14, in a view corresponding to Figure 12, shows the nozzle main body with the nozzle head, illustrating an axial offset between the air outlet openings and the fuel outlet opening at the nozzle end of the nozzle;

[0054] Figures 15A-15C show, in sections and in cross-section, different variants for the design of a final geometry of a downstream edge of the fuel pipe facing the combustion chamber; Figure 16 shows, in section, a possible further development of a nozzle of a proposed nozzle assembly with inlet lips for the two air guide channels on the nozzle head;

[0055] Figures 17A-17B show, in detail and in individual representation, different variants for a design of an inner air duct in the region of an inner air outlet opening of the inner air duct;

[0056] Figure 18A shows an engine incorporating a variant of a proposed nozzle assembly;

[0057] Figure 18B shows a detail and an enlarged scale of the combustion chamber of the engine of Figure 17A;

[0058] Figure 18C shows the structure of a conventional fuel nozzle with essential components.

[0059] Figure 18A illustrates schematically and in cross-section a (turbofan) engine T in which the individual engine components are arranged one behind the other along a rotation axis or central axis M and the engine T is designed as a turbofan engine. At an inlet or intake E of the engine T, air is moved and compressed along an inlet direction by means of a fan F. This fan F, arranged in a fan casing FC, is driven by a rotor shaft S1, which is rotated by a turbine TT of the engine T. The turbine TT is connected to a compressor V, which has, for example, an (optional) medium-pressure compressor 111 and a high-pressure compressor 112, and possibly also a low-pressure compressor (booster).The fan F supplies air to the compressor V in a primary air flow F1 on the one hand and to a secondary flow duct or bypass duct B on the other hand, to generate thrust, in a secondary air flow F2. The bypass duct B runs around a core engine comprising the compressor V, a combustion chamber assembly BK and the turbine TT, which includes a primary flow duct for the air supplied to the core engine by the fan F.

[0060] The air fed into the primary flow duct via the compressor V enters the combustion chamber assembly BK of the core engine, where thermal energy is generated to drive the turbine TT by burning fuel with air flowing in from the compressor V. For this purpose, the turbine TT has a high-pressure turbine 113, an (optional) medium-pressure turbine 114 and a low-pressure turbine 115. The turbine TT drives the rotor shafts S1, S2 and S3 and thus the medium- and high-pressure compressors as well as the fan F in order to generate thrust via the air fed into the bypass duct B. Both the air from the bypass duct B and the exhaust-air mixture from the primary flow duct of the core engine flow out via an outlet A at the end of the engine T and both contribute to the overall thrust of the engine. The outlet A usually has a thrust nozzle and a centrally arranged outlet cone C.Also common are designs in which the air from the bypass duct and the exhaust-laden air from the primary flow duct are combined into a single airflow before exiting through outlet A. To achieve this combination, bloom mixers are often used, which are arranged within the engine upstream of a common exhaust nozzle and outlet A (not shown).

[0061] Figure 18B shows a longitudinal section through the combustion chamber assembly BK of the engine T. This shows, in particular, an (annular) combustion chamber 103 of the engine T. A nozzle assembly is provided for injecting fuel or an air-fuel mixture into a combustion chamber 1030 of the combustion chamber 103. This nozzle assembly comprises a combustion chamber ring R, on which a plurality of nozzles D are arranged on a combustion chamber head of the combustion chamber along a circular line around the central axis M. One or more burner seals BD with bearing openings are provided on the combustion chamber ring R, on which nozzle heads of the respective nozzles D are held, so that fuel can be injected into the combustion chamber 103 via them. Each nozzle D comprises a flange, via which a nozzle holder DH of the nozzle D is screwed to an outer housing G of the combustion chamber assembly BK.

[0062] Figure 18C schematically shows the structure of a conventional nozzle assembly installed using a nozzle holder DH, along with its essential components. This includes an inner air duct IL with an inner swirler ID and an outer air duct AL with an outer swirler AD. Furthermore, an outer air guide 6, a central air duct 7, a central swirler 8, and a fuel injection 9 with a fuel supply line 1 are provided for supplying fuel via a fuel ring reservoir 11 and a fuel distributor 12. A burner seal BR is provided on a combustion chamber head 14.

[0063] Conventional nozzles D for an engine T are typically designed for the injection of liquid fuel, such as kerosene or diesel, and for this purpose have a central first air guide channel as well as at least one further radially outer second air guide channel and a fuel guide channel provided between the two air guide channels. Fuel emerging from a fuel outlet opening of such a fuel guide channel is then mixed at the nozzle with air from the first central air guide channel and, if necessary, also with the air from the radially further outer air guide channel, so that a fuel-air mixture is made available at one nozzle end of the nozzle D.

[0064] Such a configuration of a nozzle D can be disadvantageous under certain circumstances, particularly for fuel, in particular hydrogen, which is to be injected in gaseous form into a combustion chamber 1030 of the combustion chamber 1031. A nozzle assembly with a nozzle D according to the proposed solution, for which different embodiments are illustrated in Figures 1 to 17B, provides a remedy here. In each case, provision is made for a central fuel pipe 3, which extends along a longitudinal axis L of the nozzle and is sealed against the inflow of air, to be provided on a nozzle main body DR of the nozzle D. Fuel can be guided via said central fuel pipe 3 within the nozzle main body DR to a fuel outlet opening 33 of the fuel pipe 3 provided at a nozzle end of the nozzle D. The fuel can then be introduced from the fuel outlet opening 33 into the combustion chamber 1030 for initial mixing with air.

[0065] In a first embodiment according to Figure 1, the central fuel pipe 3 of a nozzle D is supplied with fuel via a supply reservoir in the form of an annular chamber 2A. This annular chamber 2A extends in a head region of the nozzle D, which is connected to the nozzle holder DH, in a ring shape around a first pipe section 3A of the fuel pipe 3 and is supplied with fuel via a fuel supply line 1 that runs in the nozzle holder DH. Fuel from the fuel supply line 1 thus initially reaches the annular chamber 2A via a supply opening of the fuel supply line 1, from which the fuel can flow further into the first pipe section 3A of the fuel pipe 3. The fuel flows from the annular chamber 2A via through openings 23 arranged circumferentially on an inner wall W of the first pipe section 3A, essentially radially to the longitudinal axis L of the nozzle inwards into the first pipe section 3A.

[0066] The fuel pipe 3 is sealed on the end face facing away from the combustion chamber 1030 by a continuous end wall DW of the nozzle D against air coming from the compressor V of the engine T. Fuel fed from the fuel supply line 1 into the fuel pipe 3 is also conveyed unmixed within the nozzle main body DR to the nozzle end of the nozzle D, i.e., without mixing with air. The fuel fed radially from the annular chamber 2A into the fuel pipe 3 flows from the first pipe section 3A, which defines an antechamber within the fuel pipe 3, in the axial direction into a second pipe section 3B, with a flow body 30 arranged centrally within the fuel pipe 3. The fuel flows along this flow body 30 to the fuel outlet opening 33 of the fuel pipe 3 at the nozzle end.

[0067] The central flow body 30 is cone-shaped in this case and thus defines the second pipe section 3B, which in this case has an annular cross-section (and thus an annular space axially adjoining the first pipe section 3A), in which the fuel is guided along the nozzle longitudinal axis L to the fuel outlet opening 33. The flow body 30 can be used to even out the fuel flow across the cross-section. Furthermore, the flow body 30 has a guide collar 3010 at a downstream end 301, which serves as a guide element and narrows the nozzle outlet opening 33 to accelerate the escaping fuel flow. Furthermore, the escaping fuel flow is directed radially outward via the guide collar 3010.

[0068] The fuel injected in this way is only mixed with air downstream of the fuel outlet opening 33 within the combustion chamber 1030, which is introduced into the combustion chamber 1030 via two air guide channels 4 and 5 on a nozzle head DK of the nozzle D. A first air guide channel 4 is designed as a comparatively narrow annular gap radially outward to the central fuel pipe 3 on the nozzle head DK. Radially further outward therefrom, the further air guide channel 5 is located as the radially outermost air guide channel on the nozzle head DK. Air outlet openings of the two air guide channels 4, 5 are axially set back from the fuel outlet opening 33, so that the end of the fuel pipe 3 and thus the fuel outlet opening 33 protrudes axially from the air outlet openings of the two air guide channels 4 and 5, relative to the fuel flow direction defined by the fuel pipe 3 (see also Figure 14, explained in more detail below).The inner and outer walls 43 and 45 bordering the first air duct 4 thus end further upstream than the fuel pipe 3. The same applies to an outermost wall 55 located radially further outward for the further, radially outermost air duct 5. In the radially outermost air duct 5, which has a duct width many times greater than that of the first air duct 4, swirl elements in the form of axial air swirlers 51 are provided in the embodiment variant shown in Figure 1. This generates an outer swirling air flow. (Optionally, the inner air duct 4 can also be equipped with swirl elements, although in this case the swirl imparted to the air via these elements is less than that in the outer air duct 5).

[0069] Likewise, a wired fuel flow can be generated within the second pipe section 3B of the fuel pipe 3 via axial fuel swirlers 31, which reaches the combustion chamber 1030 at the fuel outlet opening 33. In the embodiment variant of Figure 1, fuel flowing essentially radially from the annular chamber 2A via the through-openings 23 in the inner wall W into the fuel pipe 3, and here into its first pipe section 3A, will therefore initially flow further in the direction of an upstream end 300 of the pin-shaped flow body 30 spaced from the end wall DW and will then be guided radially past the flow body 30 into the second pipe section of the fuel pipe 3 with the fuel swirlers 31.The fuel flow guided on the flow body 30 over a large part of the length of the nozzle main body DR measured along the nozzle longitudinal axis L remains unmixed until it exits at the fuel outlet opening 33 and only meets the air flows from the two radially outwardly located air guide channels 4 and 5 downstream of the nozzle D.

[0070] The central, sealed guidance of the fuel in the fuel pipe 3 with the flow body 30 is particularly advantageous for highly flammable hydrogen in order to avoid flashbacks and premature self-ignition in the near field of the nozzle. The air flows provided via the air guide channels 4 and 5 also ensure advantageous recirculation zone formation downstream of the nozzle D in the combustion chamber 1030. Figure 2 illustrates the flows to be realized downstream of the nozzle end with a nozzle D of the proposed nozzle assembly. In contrast to the nozzle D of Figure 1, no single elongated, pin-shaped flow body 30 is provided within the fuel pipe 3. Rather, two axially spaced-apart first and second flow bodies 30A and 30B are provided within the fuel pipe 3.In the embodiments of Figure 2, the fuel flows from the annular space of the first pipe section 3A through a second pipe section 3B toward the fuel outlet opening 33, which is designed as a flow space with a circular cross-section. Only toward the end of the fuel pipe 3 does the fuel encounter the further (second) downstream flow body 30B, which is conical here (with the cone tip pointing toward the first, upstream flow body 30A). The fuel outlet opening 33 of the fuel pipe 3 is narrowed and also directed radially outward via the corresponding, radially widening shape of the conical flow body 30B toward its end 301.

[0071] The first upstream flow body 30A is further configured in the manner of a hub pin in the region of the fuel-pipe-side fuel distributor 31. The downstream second flow body 30B faces the combustion chamber 1030 with its blunt and, in this case, essentially planar end face 301S. Such a blunt end face 301S is also provided at the downstream end 301 of the continuous flow body 30 of Figure 1. As a result, largely identical flow patterns can be achieved.

[0072] As can be seen from Figure 2, the respective flow body 30 or 30B located at the fuel outlet opening 33, in particular with its blunt end face 301S, supports the formation of a stable recirculating combustion zone VBZ downstream of the nozzle D. Immediately in a near field behind the nozzle end D and thus downstream of the blunt end face 301S of the respective flow body 30 or 30B, an inner recirculation zone IRZ is created. In this inner recirculation zone IRZ, a comparatively high fuel concentration results, which is intended to keep the combustion temperatures low during operation of the engine T in the near field of the nozzle D. Consequently, a type of "dead water region" is created with a lower proportion of combustion or mixed air in an inner recirculation zone IRZ.

[0073] This is particularly supported by the inner and outer air guide channels 4 and 5 of the nozzle D, which adjoin the nozzle head DK in a radial direction on the outside. Thus, air is injected into the combustion chamber 1030 from the inner air outlet opening of the radially inner air guide channel 4, which is designed as a narrow annular gap. The air flow from the air outlet opening of the radially outermost air guide channel 5, which is also designed as an annular gap (with a larger cross-sectional area through which air flows), is in turn subject to strong swirl. As a result, the air flow generated here envelops the central fuel flow, draws it in radially, and thus creates a recirculation zone downstream of the nozzle D, in which air and fuel mix and which then forms the swirl-stabilized, recirculating combustion zone VBZ.

[0074] The air flow surrounding the recirculating combustion zone VBZ also creates an air-rich zone in the front area of ​​the combustion chamber 103 around the nozzle end of the nozzle D, which is identified in Figure 2 as the outer recirculation zone ORZ. The air flow in this outer recirculation zone ORZ thermally protects the nozzle D and a front combustion chamber wall of the combustion chamber 103 from the recirculating combustion zone VBZ.

[0075] Different designs of the fuel pipe 3, the air guide channels 4, 5 and in particular the flow body 30 or 30B within the fuel pipe 3 can be selected to influence the flow conditions without deviating from the proposed solution, for example with regard to the design of the combustion chamber 103, the specification of different operating parameters of the engine T (e.g., with regard to transient operating conditions, such as during acceleration and deceleration of the engine T), the setting of certain flame shapes and flame positions, the reduction of pollutants formed, such as nitrogen oxides, and the reduction of thermal loads occurring on parts of the nozzle D and / or on the combustion chamber 103.

[0076] In the embodiment of Figure 3A, for example, the central, pin-shaped flow body 30 is guided upstream within the fuel pipe 3 to a rear wall of the fuel pipe 3 or even to the end wall DW of the nozzle D. The fuel pipe 3 thus has an annular cross-section continuously along the nozzle longitudinal axis L.

[0077] In the embodiment variant of Figure 3A (as in the variant of Figure 1), radially extending support struts 303 are provided in the region of the upstream end 301 of the flow body 3 in order to stabilize the rotationally symmetrical flow body 30 in the region of the fuel outlet opening 33 and to connect it to the tube walls of the fuel tube 3. The support struts 303 are angled in this case so that a swirl imposed or generated upstream of the air flow is not reduced or even destroyed. Furthermore, one or more support struts 303 do not necessarily have to be formed close to the outlet of the fuel tube 3, but can also be located further upstream so that the flow can become homogeneous again in a subsequent (final) section of the fuel tube 3 - after the disturbance caused by the support struts 303. In the further development of Figure 3B, the support struts 303 are omitted.Only further upstream is a radial connection provided between the flow body 30 and the pipe wall of the fuel pipe 3 via the fuel swirlers 31.

[0078] An advantageous embodiment of the nozzle assembly for defined ignition of the gas-air mixture during the central injection of the gaseous fuel, in particular hydrogen, is shown in Figures 4A to 4D. An ignition element in the form of a spark plug 20 is integrated into the flow body 30, which is designed in particular as explained above and below and arranged in the nozzle assembly. The nozzle main body DR is connected to the nozzle holder DH, through which the fuel supply line 1 is routed, which in this case is connected to a central gas distribution chamber for fuel supply. The gas injection channel 16 is arranged centrally in the fuel pipe 3, and the flow body 30 is arranged coaxially. The first (and in the embodiment according to Figures 4A, 4C, 4D, sole) air channel 4, in which the axial air swirler 51 is arranged, is formed in an annular gap around the fuel pipe 3.The spark plug 20 is inserted into a coaxial cavity of the flow body 30, which is open towards the combustion chamber, and is connected to an ignition cable 19 by means of a rear cable connection 25 (cf. Figure 4C), which is guided through a rear section of the flow body 30 and a support structure for fixing the flow body 30 in the fuel pipe 3, such as support strut 303, into a supply channel of the nozzle holder 1 for connection to an electrical supply or control device (not shown here).

[0079] As Figure 4C shows, the spark plug 20 has a central electrode 21 surrounded by an insulator 29 and a ground electrode 22, and is advantageously screwed into a complementary receiving thread of the flow body 30 by means of a thread 24. In the cavity 27 of the flow body 30 containing the spark plug 20, the cable connection is provided, for example, with a cable reel 26 on the rear side of the spark plug 20 facing away from the combustion chamber 103.

[0080] A small, compact design can be selected as the spark plug 20, for example with a plug length LK in the range between 20 mm and 40 mm, for example between 25 mm and 35 mm (typically approx. 28 mm) and a diameter between approx. 6 mm and 12 mm, wherein an inner clear diameter D0 of the cavity is selected in coordination with the spark plug 20 and is e.g. 8 mm and a mean diameter D1 in the thread root is e.g. 9 mm, wherein an outer diameter D2 of the nozzle head DK around the (here only one) air channel 4 on the outside is e.g. 30 mm to 50 mm, for example approximately 36 mm. The flow body 30 in the area of ​​the fuel outlet opening 33 can also be provided with differently designed gas outlet channels 28, such as e.g. B. shown in Figure 4D in the four adjacent figures and further shown in connection with the preceding and following embodiments.

[0081] The fuel is thus introduced into the combustion chamber 1030 through the central fuel pipe 3. To optimize and fine-tune the fuel flow introduced into the combustion chamber 1030, the fuel pipe 3 can, as shown, be provided with a combination of different structures to create a suitable fuel flow, for example, by means of an axial fuel swirler that imparts angular momentum to the fuel flow. The hub of the axial fuel swirler can be, for example, a rotationally symmetrical body extending into the area of ​​the outlet plane of the fuel pipe 3 (possibly a few mm beyond), which can be designed as an extension of the hub of the axial fuel swirler and provided with additional support struts 303 at the end of the central fuel pipe 3 or without such struts, as explained, for example, with reference to Figure 3A.

[0082] The spark plug 20, inserted into the central flow body 30 in the cavity 27, is sealed from the environment. As can be seen, for example, from Figures 4A and 4B, the nozzle main body DR can have one or more air channels 4, 5. These can also be provided with support elements, with or without swirl generation. One of these support elements can be used to pass through the ignition cable 19 or supply cable (if necessary, additionally).

[0083] The spark plug is axially positioned in the flow body 30, thus achieving optimized interaction with the gaseous fuel and, for ignition, with the gas-air mixture. The particularly blunt flow body 30, the air supply via the at least one air duct 4, 5, and the supply of the gaseous fuel, in particular hydrogen, result in the resulting recirculation of the gas-air mixture toward the front ignition section or the tip of the spark plug 20. This is optimally supported by the described design, also in coordination with the installation conditions.

[0084] In an annular combustion chamber with a number of fuel nozzles arranged in a combustion chamber ring R, any number of nozzles or nozzle assemblies of the above-mentioned structure can be equipped with a spark plug 20, for example with only one, in particular at or near the highest point of the combustion chamber 103 (since gas is lighter than air), or with several, e.g. evenly distributed over the circumference, or by arrangement in every second nozzle assembly or also grouped in the nozzle assemblies, or integrated in all nozzle assemblies.

[0085] With regard to the production of a fuel tube 3 with a central flow body 30, which is not intended to have any support struts 303 in the region of its end 301 facing the combustion chamber 1030, Figure 5 illustrates a possible additive manufacturing process for the nozzle main body DR with the internal fuel tube 3. Thus, the nozzle main body DR with the flow body 30 located within the fuel tube 3 is constructed from the nozzle end, which, in the intended installed state, faces the combustion chamber 1030. The nozzle main body DR is constructed layer by layer on a mounting plate P and a support structure ST provided thereon along a vertically extending construction direction AR, which runs parallel to the nozzle longitudinal axis L, but opposite to the later flow direction of the fuel through the fuel tube 3.The nozzle main body DR with the flow body 30 is therefore additively constructed here as an integral component along the vertical on the mounting plate P. Building on the embodiment variant of Figure 2, Figures 6A and 6B, in views corresponding to Figures 1, 3A and 3B, show two exemplary embodiments in which two flow bodies 30A and 30B are provided within the central fuel pipe 3, axially spaced from one another along the nozzle longitudinal axis L. The first, upstream, pin-shaped flow body 30A, provided in the manner of a hub body in the area of ​​the fuel swirler 31, does not extend beyond half the length of the fuel pipe 3. The second flow body 30B, arranged further downstream, is conical in shape and helps define the fuel outlet opening 33.The fuel pipe 3 is locally narrowed in the region of the fuel outlet opening 33 via the second flow body 30B. Each flow body 30B is conical, with the blunt end face 301S facing the combustion chamber 1030 and the tapered end upstream and pointing in the direction of the first flow body 30A. While in the embodiment of Figure 6A the tapered end facing the first flow body 30A tapers to a point, this end is convexly curved in the embodiment of Figure 6B. This can be accompanied by a desired flow influence in the direction of the fuel outlet opening 33. The end shown in Figure 6B is merely an example of an aerodynamically optimized shape. Other aerodynamically advantageous shapes are of course also possible, such as ovoid, ogive, hemisphere or cone (with possibly blunt or rounded tip).

[0086] Regardless of the use of a single continuous flow body 30 or two axially offset flow bodies 30A, 30B within the fuel pipe 3, the illustrated embodiments each provide for a local constriction of the fuel outlet opening 33 via the respective flow body 30 or 30B provided in the region of the fuel outlet opening 33 in order to accelerate the fuel flow as it flows into the combustion chamber 1030. Thus, the respective flow body 30, 30B is then designed accordingly so that an end-side widening of the diameter of the fuel pipe 3, in order to direct the fuel flow radially outward, is at least compensated or even overcompensated by a widening of the flow body 30 or 30B towards its end. In this way, an annular gap of the fuel outlet opening 33 tapers towards the nozzle end.

[0087] The individual representations of Figures 7A to 9B illustrate different possibilities for providing additional protruding sections 304 on an outer surface of the respective flow body 30B or 30 (at least in the region of the end 301 near the fuel outlet opening). In the embodiments of Figures 7A and 7B, for example, protruding ribs 304 are provided that extend circumferentially around the nozzle's longitudinal axis L and are axially spaced from one another. This improves heat transfer from the typically metallic flow body 30B or 30 to the fuel used for cooling.

[0088] Furthermore, it is clear from the embodiment variant of Figures 7A and 7B that the blunt end face 301 S does not necessarily have to be completely flat, but can also be curved in a concave manner (towards the interior of the fuel pipe 3).

[0089] In the embodiment of Figures 8A and 8B, individual ribs 304 on an outer surface of the respective flow body 30B or 30 are spaced apart from one another in the circumferential direction around the nozzle longitudinal axis L and are each designed to be longitudinally extended. Furthermore, a convex curvature of the blunt end face 301S is provided here as an example.

[0090] In the embodiment of Figures 9A and 9B, in a modification of the embodiments of Figures 7A to 8B, a rib structure with ribs 304 is provided on a respective outer circumferential surface of a flow body 30B or 30, which ribs each run obliquely to the nozzle longitudinal axis L and thus, for example, following a section of a spiral around the nozzle longitudinal axis L (i.e., helically) along the circumferential surface. In particular, in such an embodiment, the resulting rib pattern can not only intensify heat transfer between the hotter metal of the respective flow body 30B or 30 and the cooler fuel during operation of the engine T, but can also (additionally) impart a radial movement component to the fuel flow via the respective rib structure.The projecting ribs 304 of Figures 9A and 9B are consequently arranged on the outer surface in such a way that any swirl already deliberately imposed on the fuel flow is not counteracted or such a swirl is possibly even supported.

[0091] Figures 10A and 10B show different views of an alternative surface treatment of the lateral surface of the second conical flow body 30B. Here, a plurality of recesses 305, for example in the form of holes or dents, are provided on the lateral surface around which the flow occurs. This also positively influences the flow along the lateral surface of the flow body 30B with a view to improved heat transfer.

[0092] Figure 11 shows a design of a continuous flow body 30 with a plurality of equally distributed depressions 305 on its outer surface, analogous to the variant of Figures 10A and 10B.

[0093] Figures 12 and 13 show, by way of example, two different configurations of the nozzle main body DR with the nozzle head DK without a flow body arranged within the fuel pipe 3. In contrast to the embodiment variant of Figure 12, no axial swirler 51 is provided in the radially outermost air guide channel 5 of the embodiment variant of Figure 13. Rather, one or more radial swirlers 52 are arranged within the radially outermost air guide channel 5. Regardless of the use of axial swirlers 51 or radial swirlers 52, as well as regardless of the use of one or more flow bodies 30 or 30A / 30B, an axial offset between the individual air outlet openings of the first and second air guide channels 4 and 5 and the force outlet opening 33 of the fuel pipe 3 is recommended at the nozzle end of a proposed nozzle D.In this case, for example, an (outflow) edge of the fuel pipe 3 protrudes axially the furthest along the nozzle longitudinal axis L, so that its fuel outlet opening lies in the region of a first virtual (outlet) plane E3, which runs perpendicular to the nozzle longitudinal axis L and is further downstream than further virtual planes E1 and E2, in which the air outlet openings of the radially outermost air guide duct 5 and the inner air guide duct 4 are located. The plane E3 of the central fuel pipe 3 thus protrudes the deepest into the combustion chamber 1030. The outlet plane E2 of the inner air guide duct 4, which adjoins radially further outwards, is aligned with this or - as shown in Figure 14 - is axially set back and thus penetrates somewhat less into the combustion chamber 1030. In this case, the air outlet opening of the radially outermost air guide duct 5 with the air swirler 51 (or 52) is set back the furthest axially.In principle, e3 > e2 > e1 can apply to penetration depths e3, e2, e1 of the respective outlet openings or channels and tubes. The (outlet) plane E3 of the fuel pipe 3 is thus located furthest in the combustion chamber 1030 and thus penetrates the furthest into the combustion chamber 1030. The (outlet) plane E2 of the inner air guide channel 4 is level with this plane E3 or penetrates slightly less into the combustion chamber 1030, while the (outlet) plane 1 of the outermost air guide channel 5, which serves for (stronger) air swirling, ends level with the inner air guide channel 4 or penetrates slightly less into the combustion chamber 1030.

[0094] The axial offset of the air outlet and fuel outlet openings can, for example, enable the reduction of thermal loading on the components of nozzle D at the nozzle end. Thus, zones in which fuel and air come into contact with each other, and thus heat release can occur as a result of a chemical combustion reaction, only arise further downstream of nozzle D. Furthermore, the adjusted axial offset allows for more finely adjusting the interaction of the individual flow paths with each other, in particular the influence of any imposed swirl. This can be particularly advantageous for any adjustment of the burner's stability behavior, the flame shape and position, the pollutant formation rate (in the case of hydrogen with regard to nitrogen oxides), and thermal loading of nozzle D and combustion chamber 103.

[0095] In principle, the combustion chamber-side end of the central fuel pipe 3 in the region of the fuel outlet opening 33 can have a different geometric design. However, particularly with regard to a fuel to be injected in gaseous form with rapid reaction kinetics, such as hydrogen, it must be taken into account that a flame can anchor itself very close to the nozzle end of the nozzle D. In particular, at certain operating points of the engine T, a corresponding anchor point of the recirculating combustion zone VBZ can be located directly at the trailing edge of the fuel pipe 3. Against this background, Figures 15A, 15B, and 15C illustrate, by way of example, different design options for an edge of the fuel pipe 3 facing the combustion chamber 1030 and bordering the fuel outlet opening 33.

[0096] In the embodiment variant of Figure 15A, the fuel tube 3 has a radially outwardly inclined chamfer 330 on the edge surrounding the nozzle's longitudinal axis L, which tapers to a point towards the axial end of the fuel tube 3. Such a tapered chamfer 330 has the advantage that the fuel and air flows meet tangentially. This maintains a comparatively high outflow velocity of the flows from the nozzle D, and the heat release in the region of the aforementioned anchor point remains low. However, the tapered chamfer 330 can be disadvantageous in that heat introduced in the tip region cannot be dissipated sufficiently quickly via the tube wall of the fuel tube 3. This can result in the risk of the tip being thermally overloaded during operation of the engine T unless further measures are taken.

[0097] Figures 15B and 15C show an alternative design of an end geometry of the fuel pipe 3. Here, the radially outwardly inclined chamfer 330 transitions into a blunt end geometry. While the embodiment variant of Figure 15B provides a transition into a curve, the end geometry of the embodiment variant of Figure 15C ends in a blunt end plane. In both variants of Figures 15B and 15C, fuel and air flows no longer meet in the (ideal) tangential manner as in the variant of Figure 15A. Rather, the blunt end geometry creates a small "dead water area" downstream of the end geometry, in which fuel and air can mix and in which a locally high heat release can occur due to combustion.However, the heat introduced into the final geometry can be better dissipated by heat conduction in the pipe wall of the fuel pipe than in the case of a tapered chamfer 330 according to Figure 15A.

[0098] In order to support the supply of air into the air ducts 4 and 5 at the nozzle head DK of the nozzle D, a possible further development according to Figure 16 provides for inlet lips 450 and 550 to be formed upstream on the outer wall 45 and the outermost wall 55. Via these inlet lips 450 and 550, air from the compressor V, which flows past the nozzle main body DR, is guided radially inwards into the air ducts 4 and 5. In particular, this can effectively counteract any adverse flow into the air ducts 4 and 5 due to a comparatively thick head region of the nozzle main body DR, so that a sufficiently large amount of air still reaches the air ducts 4 and 5.

[0099] The detailed view in Figures 17A and 17B illustrates possible designs of an end region of the radially inner air duct 4. Thus, in both embodiments of Figures 17A and 17B, a local narrowing of the inner air duct 4 toward its air outlet opening is provided. Sections of the inner and outer walls 43 and 45 are thus brought closer together in the area of ​​the air outlet opening. The inner air duct 4 thus narrows in a nozzle-like manner to further increase the exit velocity of the incoming air. Figure 17B also shows a slight radial deflection of the air flow in the direction of the nozzle's longitudinal axis L.

[0100] It is understood that the proposed solution is not limited to the embodiments described above, and various modifications and improvements can be made without deviating from the concepts described herein. Any of the features may be used separately or in combination with any other features, provided they are not mutually exclusive, and the disclosure extends to and encompasses all combinations and subcombinations of one or more features described herein.

[0101] List of reference symbols

[0102] 1 fuel supply line

[0103] 103 Combustion chamber

[0104] 1030 combustion chamber

[0105] 11 Fuel ring reservoir

[0106] 111 Low-pressure compressors

[0107] 112 high-pressure compressors

[0108] 113 High-pressure turbine

[0109] 114 medium-pressure turbine

[0110] 115 Low-pressure turbine

[0111] 12 Fuel distribution line

[0112] 14 Combustion chamber head

[0113] 15 central gas distribution chamber

[0114] 16 Gas injection channel (designed as a fuel pipe)

[0115] 19 ignition cables

[0116] 20 Spark plug

[0117] 21 Central electrode

[0118] 22 Ground electrode

[0119] 23 Passage opening

[0120] 24 threads

[0121] 25 cable connection

[0122] 26 cable reel

[0123] 27 Cavity for spark plug

[0124] 28 gas channels

[0125] 29 Insulator

[0126] 2A Annular chamber (supply reservoir)

[0127] 3 Fuel pipe 3A, 3B pipe section

[0128] 30, 30A, 30B flow bodies

[0129] 300, 301 end

[0130] 3010 Guide collar (guide element)

[0131] 301 S front side

[0132] 303 support strut

[0133] 304 Rib

[0134] 305 Deepening

[0135] 31 Fuel swirler (swirl element)

[0136] 33 Fuel outlet

[0137] 330 chamfer

[0138] 4 First air duct / annular gap

[0139] 43 Inner wall

[0140] 45 Outer wall

[0141] 450 inlet lip

[0142] 5 Second air duct

[0143] 51 Axial air swirler (swirl element)

[0144] 52 Radial air swirler (swirl element)

[0145] 55 Outermost wall

[0146] 550 inlet lip

[0147] 6 external air duct

[0148] 7 middle air duct

[0149] 8 medium twister

[0150] 9 Fuel injection

[0151] A Outlet

[0152] AR construction direction

[0153] AL outer air duct

[0154] AD outer twister

[0155] B Bypass channel

[0156] BK combustion chamber assembly BR burner seal

[0157] C Outlet cone

[0158] D nozzle

[0159] DO inner diameter

[0160] D1 mean diameter

[0161] D2 outer diameter

[0162] DH nozzle holder

[0163] DK nozzle head

[0164] DR nozzle main body

[0165] DW front wall

[0166] E Intake

[0167] E1, E2, E3 (exit) level

[0168] F Fan

[0169] F1 , F2 fluid flow

[0170] FC fan housing

[0171] G Outer casing

[0172] ID inner twister

[0173] IL inner air duct

[0174] IRZ Inner Recirculation Zone

[0175] L Nozzle longitudinal axis

[0176] LK candle length

[0177] M Central axis / rotation axis

[0178] ORZ Outer Recirculation Zone

[0179] P mounting plate

[0180] R combustion chamber ring

[0181] S rotor shaft

[0182] ST support structure

[0183] T (turbofan) engine

[0184] TT Turbine

[0185] V Compressor VBZ Recirculating combustion zone

[0186] W interior wall

Claims

Claims 1. Nozzle assembly for a combustion chamber (103) of an engine (T), comprising at least one nozzle (D) for injecting fuel into a combustion chamber (1030) of the combustion chamber (103), wherein the nozzle (D) comprises a nozzle body (DR) extending along a nozzle longitudinal axis (L) with a nozzle head (DK) and a nozzle holder (DH) connected to the nozzle body (DR) and having at least one fuel supply line (1), characterized in that the nozzle body (DR) comprises a central fuel tube (3) extending along the nozzle longitudinal axis (L) and at least two radially spaced air guide channels (4, 5) with at least one air outlet opening each are provided on the nozzle head (DK).

2. Nozzle assembly according to claim 1, characterized in that the fuel pipe (3) with its fuel outlet opening (33) projects axially towards the air outlet openings, with reference to the nozzle longitudinal axis (L).

3. Nozzle assembly according to claim 1 or 2, characterized in that an outer air outlet opening of a radially outermost air guide channel (5) of the at least two air guide channels (4, 5) has a larger cross-sectional area than an inner air outlet opening of an inner air guide channel (4) of the at least two air guide channels (4, 5) which is located on the nozzle head (DK) between the radial outermost air duct (5) and a section of the fuel pipe (3).

4. Nozzle assembly according to claim 3, characterized in that the outer air outlet opening has a cross-sectional area at least twice as large as the inner air outlet opening.

5. Nozzle assembly according to one of the preceding claims, characterized in that a radially inner air guide channel (4) of the two air guide channels (4, 5) is provided for supplying a non-swirling airflow into the combustion chamber (1030) or the radially inner air guide channel (4) is provided for supplying an airflow into the combustion chamber (1030) which has at least a lesser swirl than an airflow supplied into the combustion chamber (1030) via a radially outermost air guide channel (5) of the two air guide channels (4, 5).

6. Nozzle assembly according to one of the preceding claims, characterized in that at least in one radially outermost air guide channel (5) of the at least two air guide channels (4, 5) one or more axial or radial swirlers (51 , 52) are provided for air flowing into the combustion chamber (1030).

7. Nozzle assembly according to one of the preceding claims, characterized in that at least on one radially outermost air guide channel (5) of the at least two air guide channels (4, 5) one or more radially inwardly pointing inlet lips (450, 550) are provided to draw air into the radially outermost air guide channel. (5) and / or a radially inner air duct (4) of the two air ducts (4, 5). Nozzle assembly according to one of the preceding claims, characterized in that a radially inner air duct (4) of the two air ducts (4, 5) narrows towards its air outlet opening.Nozzle assembly for a combustion chamber (103) of an engine (T), in particular according to one of the preceding claims, comprising at least one nozzle (D) for injecting fuel into a combustion chamber (1030) of the combustion chamber (103), wherein the nozzle (D) comprises a nozzle body (DR) extending along a nozzle longitudinal axis (L) with a nozzle head (DK) and a nozzle holder (DH) connected to the nozzle body (DR) and having at least one fuel supply line (1), characterized in that the nozzle body (DR) comprises a central fuel tube (3) extending along the nozzle longitudinal axis (L), in which at least one centrally arranged flow element (30; 30A, 30B) is provided, on the outer surface of which fuel supplied along the fuel tube (3) can flow towards a fuel outlet opening (33) of the fuel tube (3), through which the fuel enters the combustion chamber. (1030) can be brought in.Nozzle assembly according to claim 9, characterized in that the flow body (30; 30B) extends with one end (301) to a nozzle end of the nozzle (D). Nozzle assembly according to claim 9 or 10, characterized in that. that a spark plug (20) is integrated into the fuel pipe (3), in particular into the flow body (30, 30B), with its front ignition section facing the combustion chamber (103).

12. Nozzle assembly according to claim 11, characterized in that the spark plug (20) is received in a central cavity (27) of the flow body (30, 30B).

13. Nozzle assembly according to claim 11 or 12, characterized in that a cable connection for electrical control of the spark plug (20) is guided through the flow body (30, 30B) and optionally a support element, in particular a support strut (303), of a support structure holding it in the fuel pipe (3) and through the nozzle holder (DH).

14. Nozzle assembly according to claim 11 or 12, characterized in that the flow body (30, 30B) which is bluntly formed towards the combustion chamber (103), the area of ​​the fuel outlet opening (33) and the area of ​​at least one air outlet opening of at least one air guide channel (4, 5) arranged in particular in the nozzle body (DR) are designed and coordinated in such a way that the air supply and the gas supply into the combustion chamber (103) lead to a recirculation of the gas-air mixture towards the ignition section of the spark plug (20).

15. Nozzle assembly according to one of claims to 14, characterized in that the flow body (30; 30B) has an end (301) facing the combustion chamber (1030) with a guide element (3010) via which the fuel- The fuel exiting the nozzle opening (33) is directed radially outwards with respect to the nozzle longitudinal axis (L).

16. Nozzle assembly according to one of claims 9 or 15, characterized in that the flow body (30; 30B) has a blunt end face (301 S) facing the combustion chamber (1030), at least in some areas.

17. Nozzle assembly according to claim 16, characterized in that the end face (301 S) is formed at least in certain areas substantially planar, convex or concave.

18. Nozzle assembly according to one of claims 9 to 17, characterized in that the fuel outlet opening (33) at the nozzle end is formed as an annular gap and / or locally narrowed via the flow body (30; 30B).

19. Nozzle assembly according to one of claims 9 to 18, characterized in that the flow body (30; 30A, 30B) is cone-shaped or cone-shaped.

20. Nozzle assembly according to one of claims 9 to 19, characterized in that the flow body (30; 30A, 30B) is symmetrical to the nozzle longitudinal axis (L), in particular rotationally symmetrical to the nozzle longitudinal axis (L).

21. Nozzle assembly according to one of claims 9 to 20, characterized in that the flow body (30; 30A) is connected to an end wall (DW) of the nozzle (D) or a rear wall of the fuel pipe (3).

22. Nozzle assembly according to one of claims 9 to 21, characterized in that two flow bodies (30A, 30B) are provided within the fuel pipe (3) axially spaced apart from each other with respect to the nozzle longitudinal axis (L).

23. Nozzle assembly according to one of claims 9 to 22, characterized in that the flow body (30; 30A, 30B) comprises several projecting sections (304) on its outer surface.

24. Nozzle assembly according to one of claims 9 to 23, characterized in that the flow body (30; 30A, 30B) comprises several recesses (305) on its outer surface.

25. Nozzle assembly according to one of the preceding claims, characterized in that the fuel pipe (3) has at the fuel outlet opening (33) a rim circumferential around the nozzle longitudinal axis (L) with a radially outwardly inclined chamfer (330).

26. Nozzle assembly according to claim 25, characterized in that the chamfer (330) tapers to a point at an axial end of the fuel raw res (3) or transitions into a blunt end geometry.

27. Nozzle assembly according to one of the preceding claims, characterized in that the fuel pipe (3) is sealed against an inflow of air.

28. Nozzle assembly according to one of the preceding claims, characterized in that the nozzle (D) is designed and provided for injecting gaseous fuel, in particular hydrogen.

29. Annular combustion chamber with at least one nozzle assembly of the structure according to one of the preceding claims, in particular according to one of claims 1 to 14, in a combustion chamber ring (R).

30. Ring combustion chamber according to claim 29, characterized in that a spark plug (20) is / are integrated in at least one nozzle assembly, in particular at the highest point of the combustion chamber ring (K), in several nozzle assemblies or in all nozzle assemblies.

31. Engine with at least one nozzle assembly according to one of the preceding claims. * * * * *

Images