EP3473930B1 - Nozzle for a combustion chamber of an engine - Google Patents

Description

The invention relates to a nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle outlet opening of the nozzle.

An (injection) nozzle for a combustion chamber of an engine, in particular for an annular combustion chamber of a gas turbine engine, comprises a nozzle main body having the nozzle outlet opening, which, in addition to a fuel guide channel for conveying fuel to the nozzle outlet opening, has several (at least two) air guide channels for conveying fuel to be mixed with the fuel Air has to the nozzle outlet opening. A nozzle usually also serves to swirl the supplied air, which is then mixed with the supplied fuel and conveyed into the combustion chamber at the nozzle outlet opening of the nozzle. Several nozzles are combined, for example, in a nozzle assembly, which includes several nozzles arranged next to one another, usually along a circular line, for introducing fuel into the combustion chamber.

From the prior art, for example US 2014/338353 A1 , DE 25 44 361 A1 , US 4,941,617 A , US 2007/028619 A1 and US 9,423,137 B2 , known nozzles with several air ducts and at least one fuel duct provide that a first air duct extends along a nozzle longitudinal axis of the nozzle main body and a fuel duct opposite the first air duct, based on the nozzle longitudinal axis, lies radially further out. At least one further, second air guide channel is then additionally provided radially further outward relative to the fuel guide channel, relative to the nozzle longitudinal axis. An end of the fuel guide channel, at which fuel flows out of the fuel guide channel in the direction of the air from the first air guide channel, is typically located in relation to the nozzle longitudinal axis and in the direction of the nozzle outlet opening in front of the end of the second air guide channel, from which air then flows in the direction of a mixture of air from the first air duct and fuel flows out of the fuel duct. It is also known from the prior art and, for example, also in the US 9.42 3.137 B2 It is provided to provide such a nozzle with a third third air duct, the end of which may be offset radially outwards and follows the end of the second air duct in the axial direction.

The nozzle design is of crucial importance for the combustion process in a combustion chamber of the engine's combustion chamber, as this determines the (local) distribution with which the fuel in the fuel-air mixture enters the combustion chamber. In principle, it is advantageous in this context that the fuel is distributed homogeneously in droplets in the fuel-air mixture produced. Against this background, the task is to further improve a nozzle in this regard.

In this context, a nozzle of claim 1 is proposed.

Such a nozzle has at least a first and a second air guide channel and a fuel guide channel. Between the end of the fuel guide channel and the end of the second air guide channel, a tapering or converging channel piece is formed on the nozzle with a jacket surface that is inclined in the axial direction (in cross section), based on the nozzle longitudinal axis of the nozzle main body, this jacket surface being adjacent to a radial outer lateral surface of the fuel guide channel connects.

It has been shown that an inclined lateral surface of an adjoining channel section defines a guide surface on which a (pre-) film of fuel can be applied. The geometry of the tapered channel section can be used to avoid unsteady fuel flows. Furthermore, a film of fuel, at best small, can form on the lateral surface of the tapered channel section Vibration amplitudes at a trailing edge of the fuel guide channel are exposed, which leads to a uniformization of the amount of fuel supplied and thus ultimately to a more homogeneous droplet distribution of the fuel in the fuel-air mixture that is provided at the nozzle outlet opening of the nozzle. The tapering contour of the channel piece in the direction of the end of the second air duct and thus in the direction of the nozzle outlet opening has the surprising advantage that unsteady fuel accumulations and unsteady fuel outflows at the end of the fuel duct can be avoided. A nozzle with an optimized shape as proposed can thus provide a continuous spray of fuel and air with a small droplet diameter, which in turn contributes to a reduction in the pollutants produced during combustion in the combustion chamber.

The proposed nozzle is, for example, an air-assisted injection nozzle.

The proposed nozzle can of course also be used to provide a nozzle assembly for a combustion chamber of an engine, in which several nozzles of similar or even identical design are arranged next to one another, for example next to one another along a circular line. Such a nozzle assembly is used, for example, in an annular combustion chamber of a gas turbine engine.

In one embodiment, the channel piece at the end of the nozzle main body is frusto-conical. The truncated cone shape of the channel section has proven to be advantageous for certain nozzle geometries.

In one exemplary embodiment, with a view to achieving a homogeneous fuel droplet distribution, it is provided that the channel piece tapers by at least 0.1 mm in the direction of the nozzle outlet opening. Alternatively or additionally, the taper in the direction of the nozzle outlet opening can be limited to a maximum of 4 mm. Although the dimensions and in particular the degree of taper of the channel piece appear relatively small, it has been shown that this can significantly influence the fuel-air mixture provided at the nozzle outlet opening of the nozzle.

In one exemplary embodiment, the lateral surface of the channel piece is inclined at an angle to the nozzle longitudinal axis that is less than 40°. For example, this one is Angle in a range from 1° to 40°, in particular in a range from 2° to 38° or 3° to 35° or 2° to 20°. In one exemplary embodiment, the (inclination) angle of the lateral surface of the tapered channel piece is, for example, in the range from 3° to 18°, in particular in the range from 5° to 15°.

In one embodiment variant, the channel piece extends with a length of at least 1 mm along the longitudinal axis of the nozzle. A length of the channel piece along the nozzle longitudinal axis of at least 1 mm also means, for example, that the lateral surface of the channel piece has an axial length of at least 1 mm. The length of the channel section is usually chosen so that a spatial decoupling of local vibrations, which are due to an unsteady outflow of the fuel and the two-phase mixture of fuel and air at a radially outer trailing edge of the fuel guide channel, can be achieved. The length of the channel section can vary depending on the respective engine type and therefore depend in particular on the amount of fuel to be provided or the amount of fuel-air mixture to be provided. A maximum length of the channel section along the longitudinal axis of the nozzle of less than 7 mm is considered advantageous in some embodiment variants.

In one embodiment variant, the lateral surface of the channel piece in the area of the end of the fuel guide channel is offset radially outwards by a distance in the range of 0.2 mm from an end of a lateral surface of the first air guide channel. There is therefore a local widening in the area of the end of the fuel guide channel compared to the first air guide channel via the channel piece. For example, at the end of the fuel guide channel, a channel diameter available for the outflowing fuel and the air coming from the first air guide channel increases by 2 x 0.2 mm = 0.4 mm. An outflow opening of the fuel guide channel therefore does not extend parallel to the longitudinal axis of the nozzle, for example in the US 9,423,137 B2 , but the fuel guide channel merges at its end into the axially extending and (conically) tapering channel piece.

Alternatively or additionally, in one embodiment variant it is provided that the lateral surface of the channel piece in the area of the end of the second air duct is radially offset from one end of a lateral surface of the first air duct (although of course such an offset is not mandatory). In this variant, at a rear end of the channel piece in relation to the nozzle outlet opening larger or smaller diameter is provided than at the end of the first air duct. In the first-mentioned variant, one end of the duct piece therefore does not protrude radially inwards over a virtual extension of a radially outer end edge of the first air guide duct, while in the last-mentioned variant the end of the duct piece protrudes radially inwards just over such a virtual extension. In combination with the above-explained variant of a radial attachment at the beginning of the tapered channel piece (in the area of the end of the fuel guide channel), it is specified in such a way that a diameter of the channel piece is, for example, always larger than a diameter of an upstream first air guide channel of the nozzle at the end of the fuel guide channel or at least at the end of the channel section can also be smaller.

In a possible further development, the lateral surface of the channel piece is offset radially outwards in the area of the end of the second air duct by a distance of a maximum of 1 mm from an end of a lateral surface of the first air duct. Alternatively or additionally, the lateral surface of the channel piece in the area of the end of the second air duct is offset radially inwards from an end of a lateral surface of the first air duct by a distance of a maximum of 0.1 mm.

In particular, based on the channel geometries explained above on the tapered channel piece, it can be provided in one embodiment variant that the channel piece at its widest point in the area of the end of the fuel guide channel has a diameter that is 0.4 mm larger than the first air guide channel at the end of the fuel guide channel, i.e. at the point where the fuel guide channel opens into the first air guide channel. The diameter of the channel piece can of course also be larger at its widest point by a smaller amount than the diameter of the first air guide channel at the end of the fuel guide channel. In one variant, it would even be conceivable that the diameter of the channel section at its widest point corresponds to the diameter of the first air guide channel at the end of the fuel guide channel.

Alternatively or additionally, it can be provided that the duct piece at its narrowest point in the area of the end of the second air duct has a maximum diameter of 2 mm, in particular a maximum of 1.4 mm larger and/or a maximum of 0.2 mm smaller than the first air duct at the end of the fuel channel. As already explained above, the channel piece in the first-mentioned variant also has a larger diameter than that at its rear end, based on the flow direction of the air, the fuel or the fuel-air mixture first air duct at the end of the fuel duct, here a diameter that is at least 0.2 mm larger. For example, it can be provided that the channel piece has a diameter at least 0.2 mm larger at its narrowest point in the area of the end of the second air guide channel than the first air guide channel at the end of the fuel guide channel. In the other variant mentioned, the channel piece tapers or converges over its length to such an extent that the channel piece in the area of the end of the second air duct and thus at its narrowest point at the end has a diameter that is equal to or smaller than the diameter of the first Air duct is at the end of the fuel duct.

With a view to avoiding transient fuel accumulations and fuel outflows at the end of the fuel guide channel, specifying a specific relationship between parameters defining the geometry of the channel section can be advantageous. In an embodiment variant according to the invention it is provided that the lateral surface of the channel piece in the area of the fuel guide channel is offset radially outwards by a distance Δr ₁ from one end of a lateral surface of the first air guide channel and the channel piece extends with a length x _PF along the nozzle longitudinal axis of the nozzle main body and then the following applies: $${\mathrm{x}}_{\mathrm{PF}}\ge 2\Delta {\mathrm{r}}_{\mathrm{1}}.$$

In a further development, x _PF ≥ 3 Δr ₁ can also apply.

In particular, for x _PF ≥ 2 Δr ₁ or x _PF ≥ 3 Δr ₁ it can also apply, as already explained above, that the length x _PF is, for example, greater than or equal to 2 mm and the radial distance Δr ₁ <1 mm, in particular ≤ 0 .8 mm and e.g. ≤ 0.665 mm.

In one exemplary embodiment, the radially outer lateral surface of the fuel guide channel merges into the inclined lateral surface of the channel piece via a curve. A continuous and edge-free transition between the radially outer lateral surface of the fuel guide channel and the lateral surface of the adjoining channel section can further support the temporally and spatially uniform fuel delivery or fuel injection. For example, the (convex) curve at the transition between the radially outer lateral surface of the fuel guide channel and the inclined lateral surface of the channel piece has a radius of a maximum of 8 mm. In one embodiment variant, the curve has a radius of a maximum of 2 mm.

In an embodiment variant according to the invention, a concave curve can be provided on a radially inner lateral surface of the fuel guide channel, via which a section of the radially inner lateral surface pointing obliquely radially inwards merges into an axially extending section of the radially inner lateral surface. In particular, in such an embodiment variant in which one end of the radially inner edge of the fuel guide channel still extends axially, a convex curve can be formed opposite on the radially outer lateral surface. This opposite rounding of the radially outer lateral surface then has, as stated above, for example a radius of a maximum of 8 mm and thus enables a smoother transition of the fuel guide channel to the tapered channel piece. A concave curve on the radially inner lateral surface of the fuel guide channel has, for example, a radius of a maximum of 15 mm, in particular, for example, a maximum of 10 mm, 8 mm, 5 mm or 2 mm.

In order to avoid local backflows, it is provided in one exemplary embodiment that a sharp-edged transition is formed at the end of the fuel guide channel between a lateral surface of the first air guide channel and an inner lateral surface of the fuel guide channel. Here, for example, a wall section of the nozzle main body, which on the one hand forms the inner (radially inner) lateral surface of the fuel guide channel and on the other hand the (radially outer) lateral surface of the first air guide channel, is designed to taper to an edge at the end of the fuel guide channel and the first air guide channel.

Alternatively or additionally, in order to avoid local backflows, a sharp-edged transition can be formed at the end of the tapered channel piece between the lateral surface of the channel piece and an inner lateral surface of the second air duct. Analogously, a wall section of the nozzle main body, which forms the lateral surface of the channel piece on the one hand and the radially inner lateral surface of the second air guide channel on the other hand, can be designed to taper in the direction of the nozzle outlet opening. The result here is a sharp edge at the end of the channel section at the transition to an outflow opening of the second air guide channel.

The proposed solution also includes a nozzle assembly with several identically designed nozzles, each of which forms a tapered channel piece between the end of a fuel guide channel and the end of a second air guide channel on a nozzle in the area of the nozzle outlet opening of the respective nozzle. Further is also comprises an engine with at least one such nozzle or such a nozzle group.

The attached figures illustrate exemplary possible embodiment variants of the proposed solution.

Figur 1A

in vergrößertem Maßstab und ausschnittsweise den Bereich an einer Düsenaustrittsöffnung eine Düse mit einem sich konisch verjüngenden Kanalstück zwischen dem Ende eines Kraftstoffleitkanals und einem Ende eines zweiten Luftleitkanals der Düse zur Vermeidung instationärer Kraftstoffansammlungen und Kraftstoffabströmungen am Ende des Kraftstoffleitkanals;

Figur 1B

in mit der Figur 1A übereinstimmender Ansicht eine mögliche Weiterbildung der Ausführungsvariante der Figur 1A;

Figur 1C

eine ausschnittsweise vergrößerte Darstellung einer Weiterbildung des Kanalstücks der Figur 1A;

Figur 2A

ein Triebwerk, in dem eine Brennkammer mit einer Düse entsprechend der Figur 1 zum Einsatz kommt;

Figur 2B

ausschnittsweise und in vergrößertem Maßstab die Brennkammer des Triebwerks der Figur 2A;

Figur 2C

in Querschnittsansicht den grundsätzlichen Aufbau der Düse der Figur 1 und die umliegenden Komponenten des Triebwerks im eingebauten Zustand der Düse.

Show here:

Figure 1A

on an enlarged scale and in detail the area at a nozzle outlet opening, a nozzle with a conically tapering channel piece between the end of a fuel guide channel and an end of a second air guide channel of the nozzle to avoid unsteady fuel accumulations and fuel outflows at the end of the fuel guide channel;

Figure 1B

in with the Figure 1A Consistent view of a possible further development of the embodiment variant Figure 1A ;

Figure 1C

a partially enlarged representation of a further development of the channel piece Figure 1A ;

Figure 2A

an engine in which a combustion chamber with a nozzle corresponding to the Figure 1 is used;

Figure 2B

detail and on an enlarged scale the combustion chamber of the engine Figure 2A ;

Figure 2C

a cross-sectional view of the basic structure of the nozzle Figure 1 and the surrounding components of the engine with the nozzle installed.

The Figure 2A illustrates schematically and in a sectional view 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 sucked in along an inlet direction by means of a fan F. This one in one Fan F arranged in the fan housing FC is driven by a rotor shaft S, which is rotated by a turbine TT of the engine T. The turbine TT is connected to a compressor V, which has, for example, a low-pressure compressor 11 and a high-pressure compressor 12, and possibly also a medium-pressure compressor. On the one hand, the fan F supplies air to the compressor V in a primary air flow F1 and, on the other hand, to generate the thrust, in a secondary air flow F2, a secondary flow channel or bypass channel B. The bypass channel B runs around a core engine comprising the compressor V and the turbine TT, which comprises a primary flow duct for the air supplied to the core engine by the fan F.

The air conveyed into the primary flow channel via the compressor V reaches a combustion chamber section BK of the core engine, in which the drive energy for driving the turbine TT is generated. For this purpose, the turbine TT has a high-pressure turbine 13, a medium-pressure turbine 14 and a low-pressure turbine 15. The turbine TT uses the energy released during combustion to drive the rotor shaft S and thus the fan F in order to generate the required thrust via the air conveyed into the bypass channel B. Both the air from the bypass duct B and the exhaust gases from the primary flow duct of the core engine flow out via an outlet A at the end of the engine T. The outlet A usually has a thrust nozzle with a centrally arranged outlet cone C.

Figure 2B shows a longitudinal section through the combustion chamber section BK of the engine T. This shows in particular a (ring) combustion chamber 3 of the engine T. A nozzle assembly is provided for injecting fuel or an air-fuel mixture into a combustion chamber 30 of the combustion chamber 3. This comprises a combustion chamber ring R, on which several (fuel/injection) nozzles 2 are arranged along a circular line around the central axis M. Here, the nozzle outlet openings of the respective nozzles 2, which lie within the combustion chamber 3, are provided on the combustion chamber ring R. Each nozzle 2 includes a flange via which a nozzle 2 is screwed to an outer housing G of the combustion chamber 3.

The Figure 2C now shows a cross-sectional view of the basic structure of a nozzle 2 as well as the surrounding components of the engine T in the installed state of the nozzle 2. The nozzle 2 is part of a combustion chamber system of the engine T. The nozzle 2 is located downstream of a diffuser D and is used during assembly through an access hole L through a combustion chamber head 31, through a heat shield 300 and a head plate 310 the Combustion chamber 3 is inserted up to the combustion chamber 30 of the combustion chamber 3, so that a nozzle outlet opening formed on a nozzle main body 20 extends into the combustion chamber 30. The nozzle 2 further comprises a nozzle trunk 21 which extends essentially radially with respect to the central axis M and in which a fuel supply line 210 is accommodated, which delivers fuel to the nozzle main body 20. A fuel chamber 22, fuel passages 220, heat shields 23 and air chambers for insulation 23a and 23b are also formed on the nozzle main body 20.

In addition, the nozzle main body 20 forms a (first) inner air guide channel 26 running centrally along a nozzle longitudinal axis DM and, for this purpose, outer air guide channels 27a and 27b located radially further outwards. These air guide channels 26, 27a and 27b extend in the direction of the nozzle outlet opening of the nozzle 2.

Furthermore, at least one fuel guide channel 25 is formed on the nozzle main body 20. This fuel guide channel 25 lies between the first inner air guide channel 26 and the second outer air guide channel 27a. The end of the fuel guide channel 25, through which fuel flows out of the first inner air guide channel 26 in the direction of the air during operation of the nozzle 2, lies, based on the nozzle longitudinal axis DM and in the direction of the nozzle outlet opening, in front of an end of the second air guide channel 27a, from which air flows out of the second, outer air guide channel 27a in the direction of a mixture of air from the first, inner air guide channel 26 and fuel from the fuel guide channel 25.

In the outer air guide channels 27a and 27b, twisting elements are usually provided for twisting the air supplied through them (cf. Figure 1 ). Furthermore, the nozzle main body 20 also includes an outer, radially inwardly pointing air guide element 41 at the end of the third outer air guide channel 27b. To seal the nozzle 2 from the combustion chamber 30, a sealing element 28 is also provided on the circumference of the nozzle main body 20. This sealing element 28 forms a counterpart to a so-called burner seal 4. This burner seal 4 is floatingly mounted between the heat shield 300 and the head plate 310 in order to compensate for radial and axial movements between the nozzle 2 and the combustion chamber 3 in different operating states and to ensure a reliable seal .

The burner seal 4 usually has a flow guide element 40 to the combustion chamber 30. This flow guide element 40 ensures connection with the third outer one Air guide channel 41 on the nozzle 2 for a desired flow guidance of the fuel-air mixture that arises from the nozzle 2, more precisely the wired air from the air guide channels 26, 27a and 27b and the fuel guide channel 25.

At nozzle 2 the Figure 2C , which is a pressure-supported injection nozzle, follow, based on the nozzle longitudinal axis DM and in the direction of the nozzle outlet opening, the end of the fuel guide channel 25, from which during operation of the engine T fuel the air from the first inner, centrally extending air guide channel 26 is supplied to the ends of the second and third radially outer air guide channels 27a and 27b. In order to avoid unsteady fuel accumulations and fuel outflows at this end of the fuel guide channel 25 during operation of the engine T and to achieve a temporal and spatial uniformity of the fuel delivery or fuel injection, a geometrically optimized design of the nozzle end (the end of the nozzle main body 20) is proposed in this respect . An embodiment variant of this is illustrated by: Figure 1 on an enlarged scale.

At one in the Figure 1A 2, a tapering channel piece 9 with a lateral surface 292b which is inclined in the axial direction is formed on the nozzle 2 between the end of the fuel guide channel 25 and the end of the second air guide channel 27a. The inclined lateral surface 292b of the channel piece 9 adjoins a radially outer lateral surface 291b of the fuel guide channel 25. The lateral surfaces 291b and 292b run at an angle greater than 10° to one another in order to define a pre-film or 'prefilm' surface for the fuel system which extends in the direction of the nozzle outlet opening via the lateral surface 292b adjoining the fuel guide channel 25. The fuel guide channel 25 thus merges into the channel piece 9, which tapers in the direction of the nozzle outlet opening and thus towards one end of the second radially outer air guide channel 27a or which converges in the direction of the nozzle outlet opening.

The fuel guide channel 25 is formed at the end of the nozzle 2 with a channel section 251 that is angled radially inwards. This angled channel section 251 adjoins a channel section 250 of the fuel guide channel 25 which runs essentially parallel to the nozzle longitudinal axis DM and which corresponds to the cross-sectional view of Figure 1A is bordered by inner and outer lateral surfaces 290a and 290b that run parallel to one another. While then a radially internal one Lateral surface 291a of the adjoining, angled channel section 251 is guided up to a lateral surface of the first air duct 26, the opposite, radially outer lateral surface 291b of the angled channel section 251 merges into the lateral surface 292b of the channel piece 9, which is opposite the first, inner air duct 26 has a larger diameter. In the present case, the transition between the fuel guide channel 25 and the channel piece 9 in the area of the lateral surfaces 291b and 292b is continuous and edge-free via a curve that has a radius R _PFO , here of a maximum of 2 mm.

The (consistently) larger diameter of the channel piece 9 compared to the diameter of the inner, first air guide channel 26 results from a radial offset of the outer lateral surface 292b of the channel piece 9 to one end of the lateral surface of the first air guide channel 26. The fuel guide channel 25 is therefore not complete except for the diameter of the first air duct 26. The diameter of the channel piece 9 at its widest point in the area of the end of the fuel guide channel 25 is larger by a distance 2Δr ₁ than a diameter 2r _inside the first air guide channel 26 at the end of the fuel guide channel 25. The lateral surface 292b of the channel piece 9 is thus in the area of End of the fuel guide channel 25 is offset radially outwards by a distance Δr ₁ to one end of the lateral surface of the first air guide channel 26. In the embodiment variant shown, the distance Δr ₁ is less than 0.8 mm, in particular less than 0.665 mm. For example, the distance Δr ₁ can be at least 0.2 mm and a maximum of 2 mm. In principle, Δr ₁ can also be smaller than 0.2 mm or even zero.

The channel piece 9 tapers over a length x _PF in the direction of the nozzle outlet opening. However, an offset to the end of the first air duct 26 remains. The lateral surface 292b of the channel piece 9 is also in the area of the end of the second air guide channel 27b and thus at the (rear, downstream) end of the channel piece 9 radially by a distance Δr ₂ (with 0 ≤ Δr ₂ <Δr ₁ ) to the lateral surface of the first Air duct 26 offset. Accordingly, the lateral surface 292b of the channel piece 9 extends radially inwards, but not over a virtual extension of a radially outer end edge of the first air duct 26. The virtual extension of the radially outer end edge of the first air duct 26 is in the Figure 1A represented via a reference axis RF. The diameter of the channel piece 9 is therefore always larger than the diameter of the first air channel 26 at the end of the fuel channel 25. In the embodiment variant shown Figure 1A a distance Δr ₂ is, for example, at least 0.1 mm, in particular 0.2 mm.

The taper of the channel piece 9 is also chosen so that the lateral surface 292b of the channel piece 29 runs at an angle α ≤ 40 ° to the nozzle longitudinal axis DM. A constant flow of fuel to the nozzle outlet opening can be achieved during operation via such a taper over a length of x _PF of at least 1 mm, in particular at least 2 mm. Furthermore, a spatial decoupling of local vibrations due to an unsteady outflow of fuel and a two-phase mixture of fuel and air at a radially outer trailing edge of the fuel guide channel 25 can be avoided. Unsteady fuel accumulations and fuel outflows at the end of the fuel guide channel 25 are also avoided. The fuel is delivered more evenly via the lateral surface 292b of the channel piece 9, which then serves as a guide surface for a film of fuel, which results in a more homogeneous distribution of fuel droplets in the fuel-air mixture at the nozzle outlet opening. A resulting continuous spray with a small fuel droplet diameter then in turn leads to a reduction in pollutants produced during combustion in the combustion chamber 30. The length x _PF can, for example, be limited to a maximum of 7 mm. For example, x _PF ≥ 3 Δr ₁ .

In deviation from that in the Figure 1 In the variant shown, the distances Δr ₁ and Δr ₂ and the length x _PF can also be selected differently, in particular depending on a predetermined mass flow of fuel at certain predetermined operating points of the engine T and the diameter 2r _inside the inner first air duct 26. The length in x _PF should, for example, be so long that locally unsteady effects due to the outflow of fuel from the fuel guide channel 25 are spatially separated from a multi-phase flow at an (atomizer) edge e _II . This edge e _II is formed at a transition between the lateral surface 292b of the channel piece 9 and a radially inner lateral surface of the second outer air guide duct 27a. The edge en is also designed to be as pointed as possible in order to avoid local backflows at the tapered end of the channel piece 9. A wall section 29b of the nozzle main body 2, which on the one hand forms the lateral surface of the channel piece 9 and on the other hand forms the radially inner lateral surface of the second air guide channel 27a, thus tapers towards the edge e _II at the end of the channel piece 9 and the second air guide channel 27a. As a result, a sharp-edged transition is formed between the lateral surface 292b of the channel piece 9 and the inner lateral surface of the second air guide duct 27a.

Likewise, to avoid backflows, a sharp-edged transition is formed at the end of the fuel guide channel 25 between the lateral surface of the first air guide channel 26 and the inner lateral surface 291a of the fuel guide channel 25. A wall section 29a of the nozzle main body 2, which forms the inner lateral surface 291a of the fuel guide channel 25 on the one hand and the lateral surface of the first air guide channel 26 on the other hand, here also tapers to an edge e _I at the end of the fuel guide channel 25 and the first air guide channel 26.

Furthermore, it is of course not mandatory that the end of the lateral surface 292b of the channel piece 9 and therefore the (terminating) edge e _II lies radially on the outside with respect to the reference axis RF. In one embodiment variant, the (terminating) edge en can also lie radially further inward with respect to the radially inner (terminating) edge e _I of the fuel guide channel 25, so that a value for Δr ₂ can be "negative", i.e. r _inner > r _outer applies , where 2 r _outer corresponds to the diameter of the channel piece 9 at its nozzle outlet end (on the edge e _II ). For example, in such an embodiment variant, the geometry in the area of the channel piece 9 corresponds to the enlarged detail of the illustration Figure 1C characterized by Δr ₁ = 0.2 mm, Δr ₂ = 0.1 mm and R _PFO = 1.0 mm.

At one in the Figure 1B illustrated further development of the embodiment variant Figure 1A adjoining the angled channel section 251 of the fuel guide channel 25 downstream is an (end) section of the fuel guide channel 25, which runs axially in the direction of the nozzle outlet opening. Here, a concave curve is provided on the radially inner lateral surface 291a of the fuel guide channel 25, via which the angled and thus obliquely radially inwardly pointing section of the radially inner lateral surface merges into an axially extending section. In the present case, the concave curve has a radius R _Duct of a maximum of 15 mm and lies opposite the convex curve on the radially outer lateral surface 291b with the radius R _PFO . An axial length I of the axially extending, radially inner end section of the fuel guide channel 25 corresponds, for example, to only a fraction of the length x _PF . For example, this length I is less than 0.5 x _PF .

The radius R _PFO can vary depending on the size of the curve on the radially inner lateral surface 291a and in particular the associated axial length of the axially extending (and tapering at the end up to the edge _e1 ) radially inner end section of the fuel guide channel 25 . With an existing axially extending, radially inner end section of the fuel guide channel 25 and a concave rounding with radius R _Duct for the transition, where 0 < R _Duct ≤15 mm applies, the radius R _PFO of the convex rounding on the radially outer lateral surface 291b is a maximum of 8 mm.

Reference symbol list

11

Low pressure compressor

12

High pressure compressor

13

High pressure turbine

14

Medium pressure turbine

15

Low pressure turbine

2

jet

20

Nozzle main body

21

tribe

210

Fuel supply line

22

Fuel chamber

220

Fuel passage

23

Heat shield

24a, 24b

Air chamber

25

Fuel channel

250, 251

Canal section

26

First air duct

27a

Second air duct

27b

Third air duct

28

Sealing element

290a, 290b, 291a, 291b

Lateral surface

292b

Shell surface / guide surface

29a, 29b

Wall section

3

combustion chamber

30

combustion chamber

300

Heat shield

31

Combustion chamber head

310

Headstock

4

Burner gasket

40

Flow guide element

41

Air guide element

9

Channel piece

A

outlet

b

Bypass channel

BK

Combustion chamber section

C

outlet cone

D

diffuser

DM

Nozzle longitudinal axis

E

Inlet / Intake

ei, ei

Edge

F

fan

F1, F2

Fluid flow

FC

Fan housing

G

Outer casing

L

Access hole

I

length

M

Central axis / rotation axis

R

Combustion chamber ring

RF

Reference axis

rinner, router

radius

RDuct, RPFO

radius

S

Rotor shaft

T

(Turbofan) engine

TT

turbine

v

compressor

xPF

length

Δr1, Δr2

Distance

α

Angle *****

Claims (13)

1. Nozzle for a combustion chamber (3) of an engine (T) for providing a fuel-air mixture at a nozzle outlet opening of the nozzle (2), wherein the nozzle (2) comprises a nozzle main body (20) having the nozzle outlet opening and extending along a nozzle longitudinal axis (DM), and the nozzle main body (20) furthermore comprises at least the following:

   - at least one first air-guiding duct (26) extending along the nozzle longitudinal axis (DM) for conveying air to the nozzle outlet opening,

   - at least one fuel-guiding duct (25) lying radially further outwards in relation to the first air-guiding duct (26), with reference to the nozzle longitudinal axis (DM), for conveying fuel to the nozzle outlet opening, and

   - at least one further, second air-guiding duct (27a) lying radially further outwards in relation to the fuel-guiding duct (25), with reference to the nozzle longitudinal axis (DM),

   wherein one end (e_I) of the fuel-guiding duct (25), at which end fuel flows out of the fuel-guiding duct (25) in the direction of the air from the first air-guiding duct (26), lies, with reference to the nozzle longitudinal axis (DM) and in the direction of the nozzle outlet opening, in front of the end of the second air-guiding duct (27a), from which end air flows out of the second air-guiding duct (27a) in the direction of a mixture of air from the first air-guiding duct (26) and fuel from the fuel-guiding duct (25), and

   wherein between the end (e_I) of the fuel-guiding duct (25) and the end of the second air-guiding duct (27a), a tapering duct piece (9) is formed on the nozzle (2) with a lateral surface (292b) running, with reference to the nozzle longitudinal axis (DM), at an inclination in the axial direction and adjoining a radially outer lateral surface (291b) of the fuel-guiding duct (25),

   characterized in that

   - on a radially inner lateral surface (291a) of the fuel-guiding duct (25) a concave rounded portion (R_DUCT) is provided via which an obliquely radially inwardly pointing portion of the radially inner lateral surface (291a) merges into a portion of the radially inner lateral surface (291a), said portion running axially at the end of the fuel-guiding duct (25), and/or

   - a diameter of the tapering duct piece (9) at its widest point is greater by a distance 2Δr₁ than a diameter 2r_inner of the first air-guiding duct (26) at the end (e_I) of the fuel-guiding duct (25), and the duct piece (9) tapers from its widest point over a length x_PF along the nozzle longitudinal axis (DM) as far as a diameter 2r_outer at the nozzle outlet opening, wherein $${\mathrm{x}}_{\mathrm{PF}}\ge 2\Delta {\mathrm{r}}_{\mathrm{1}}.$$

   
2. Nozzle according to Claim 1, characterized in that the duct piece (9) is frustoconical.
3. Nozzle according to Claim 1 or 2, characterized in that the duct piece (9) tapers by at least 0.1 mm and/or by a maximum of 4 mm over the length x_PF in the direction of the nozzle outlet opening.
4. Nozzle according to one of the preceding claims, characterized in that the lateral surface (292b) of the duct piece (9) runs inclined at an angle (α), which is smaller than 40°, with respect to the nozzle longitudinal axis (DM).
5. Nozzle according to one of the preceding claims, characterized in that the length x_PF is at least 1 mm and/or a maximum of 7 mm.
6. Nozzle according to one of the preceding claims, characterized in that the lateral surface (292b) of the duct piece (9) in the region of the end of the fuel-guiding duct (25) is offset radially outwards by a distance Δr₁ of at least 0.2 mm from an end of a lateral surface of the first air-guiding duct (26).
7. Nozzle according to one of the preceding claims, characterized in that the lateral surface (292b) of the duct piece (9) in the region of the end of the second air-guiding duct (27a) is offset radially from an end of a lateral surface of the first air-guiding duct (26).
8. Nozzle according to Claim 7, characterized in that the lateral surface (292b) of the duct piece (9) in the region of the end of the second air-guiding duct (27a) is offset by a distance Δr₂ of a maximum of 1 mm radially outwards and/or by a distance Δr₂ of a maximum of 0.1 mm radially inwards from an end of a lateral surface of the first air-guiding duct (26).
9. Nozzle according to one of the preceding claims, characterized in that the radially outer lateral surface (291b) of the fuel-guiding duct (25) merges via a rounded portion into the inclined lateral surface (292b) of the duct piece (9).
10. Nozzle according to Claim 9, characterized in that the rounded portion has a radius (R_PFO) of a maximum of 8 mm, in particular of a maximum of 2 mm.
11. Nozzle according to one of the preceding claims, characterized in that the concave rounded portion of the radially inner lateral surface (291a) has a radius (R_Duct) of a maximum of 15 mm.
12. Nozzle according to one of the preceding claims, characterized in that a sharp-edged transition is formed at the end of the fuel-guiding duct (25) between a lateral surface of the first air-guiding duct (26) and an inner lateral surface (291a) of the fuel-guiding duct (25), and/or a sharp-edged transition is formed at the end of the duct piece (9) between the lateral surface (292b) of the duct piece (9) and an inner lateral surface of the second air-guiding duct (27a).
13. Engine having at least one nozzle according to one of Claims 1 to 12.

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