Nozzle for a combustion chamber of an engine

Abstract

A nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle exit opening of the nozzle includes a nozzle main body including the nozzle exit opening and extends along a nozzle longitudinal axis. The nozzle main body has a first air guiding channel, a fuel guiding channel and a further, radially outwardly second air guiding channel. One end of the fuel guiding channel is positioned in front of the end of the second air guiding channel. A tapering channel portion with a shell surface inclined with respect to a nozzle longitudinal axis in the axial direction and connects to a radially outer shell surface of the fuel guiding channel is formed between the end of the fuel guiding channel and the end of the second air guiding channel at the nozzle.

Claims

1. A nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle exit opening of the nozzle, the nozzle comprising: a nozzle main body that comprises the nozzle exit opening and that extends along a nozzle longitudinal axis, the nozzle main body further comprising: a first air guiding channel for conveying air to the nozzle exit opening, the first air guiding channel also extending along the nozzle longitudinal axis, a fuel guiding channel for conveying fuel to the nozzle exit opening that is positioned radially further outwardly as compared to the first air guiding channel with respect to the nozzle longitudinal axis, and a second air guiding channel that is positioned radially further outwardly as compared to the fuel guiding channel with respect to the nozzle longitudinal axis, wherein an end of the fuel guiding channel at which fuel from the fuel guiding channel flows out in a direction of the air from the first air guiding channel, is positioned—with respect to the nozzle longitudinal axis and in a direction of the nozzle exit opening—in front of an end of the second air guiding channel from which air from the second air guiding channel flows out in a direction of a mixture of air from the first air guiding channel and fuel from the fuel guiding channel, a tapering channel portion with a first channel surface inclined with respect to the nozzle longitudinal axis in an axial direction and connecting to a radially outer second channel surface of the fuel guiding channel, the tapering channel portion positioned between the end of the fuel guiding channel and the end of the second air guiding channel, the tapering channel portion ending at the end of the second air guiding channel; wherein the second channel surface transitions into the first channel surface via a curvature; wherein the curvature has a radius of maximally 8 mm.

2. The nozzle according to claim 1, wherein the tapering channel portion is shaped as a truncated cone.

3. The nozzle according to claim 1, wherein the tapering channel portion tapers off in the direction of the nozzle exit opening by at least 0.1 mm and/or by maximally 4 mm.

4. The nozzle according to claim 1, wherein the first channel surface extends in an inclined manner at an angle to the nozzle longitudinal axis that is smaller than 40°.

5. The nozzle according to claim 1, wherein the tapering channel portion extends with a length of at least 1 mm and/or of maximally 7 mm along the nozzle longitudinal axis.

6. The nozzle according to claim 1, wherein, in an area of the end of the fuel guiding channel, the first channel surface is offset radially outwards by a distance of at least 0.2 mm to an end of a surface of the first air guiding channel.

7. The nozzle according to claim 1, wherein, in an area of the end of the second air guiding channel, the first channel surface is offset radially outwards to an end of a fourth channel surface of the first air guiding channel.

8. The nozzle according to claim 1, wherein, in the area of the end of the second air guiding channel, the first channel surface is offset radially outwards by a distance of maximally 1 mm or is offset radially inwards by a distance of maximally 0.1 mm to an end of a fourth channel surface of the first air guiding channel.

9. The nozzle according to claim 1, wherein, in an area of the end of the fuel guiding channel, the first channel surface is offset radially outwards by a distance (Δr1) to an end of a fourth channel surface of the first air guiding channel, and the tapering channel portion extends with a length (xPF) along the nozzle longitudinal axis, with xPF≥2Δr1.

10. The nozzle according to claim 1, wherein, at a radially inner third surface of the fuel guiding channel, a concave curvature is provided via which an upstream obliquely radially inward oriented section of the third surface transitions into a section of the third surface that extends axially at the end of the fuel guiding channel.

11. The nozzle according to claim 10, wherein the concave curvature of the third surface has a radius of maximally 15 mm.

12. The nozzle according to claim 1, wherein a sharp-edged transition is formed at the end of the fuel guiding channel between a fourth channel surface of the first air guiding channel and a radially inner third channel surface of the fuel guiding channel, and/or that a sharp-edged transition is formed at the end of the tapering channel portion between the first channel surface and an inner channel surface of the second air guiding channel.

13. An engine with the nozzle according to claim 1.

14. The nozzle according to claim 12, wherein the curvature has a radius of maximally 2 mm.

15. A nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle exit opening of the nozzle, the nozzle comprising: a nozzle main body that comprises the nozzle exit opening and that extends along a nozzle longitudinal axis, the nozzle main body further comprising: a first air guiding channel for conveying air to the nozzle exit opening, the first air guiding channel also extending along the nozzle longitudinal axis, a fuel guiding channel for conveying fuel to the nozzle exit opening that is positioned radially further outwardly as compared to the first air guiding channel with respect to the nozzle longitudinal axis, and a second air guiding channel that is positioned radially further outwardly as compared to the fuel guiding channel with respect to the nozzle longitudinal axis, wherein an end of the fuel guiding channel at which fuel from the fuel guiding channel flows out in a direction of the air from the first air guiding channel, is positioned—with respect to the nozzle longitudinal axis and in a direction of the nozzle exit opening—in front of an end of the second air guiding channel from which air from the second air guiding channel flows out in a direction of a mixture of air from the first air guiding channel and fuel from the fuel guiding channel, a tapering channel portion with a first channel surface inclined with respect to the nozzle longitudinal axis in an axial direction and connecting to a radially outer second channel surface of the fuel guiding channel, the tapering channel portion positioned between the end of the fuel guiding channel and the end of the second air guiding channel; wherein, in an area of the end of the fuel guiding channel, the first channel surface is offset radially outwards by a distance (Δr1) to an end of a fourth channel surface of the first air guiding channel, and the tapering channel portion extends with a length (xPF) along the nozzle longitudinal axis, with xPF≥2Δr1.

16. A nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle exit opening of the nozzle, the nozzle comprising: a nozzle main body that comprises the nozzle exit opening and that extends along a nozzle longitudinal axis, the nozzle main body further comprising: a first air guiding channel for conveying air to the nozzle exit opening, the first air guiding channel also extending along the nozzle longitudinal axis, a fuel guiding channel for conveying fuel to the nozzle exit opening that is positioned radially further outwardly as compared to the first air guiding channel with respect to the nozzle longitudinal axis, and a second air guiding channel that is positioned radially further outwardly as compared to the fuel guiding channel with respect to the nozzle longitudinal axis, wherein an end of the fuel guiding channel at which fuel from the fuel guiding channel flows out in a direction of the air from the first air guiding channel, is positioned—with respect to the nozzle longitudinal axis and in a direction of the nozzle exit opening—in front of an end of the second air guiding channel from which air from the second air guiding channel flows out in a direction of a mixture of air from the first air guiding channel and fuel from the fuel guiding channel, a tapering channel portion with a first channel surface inclined with respect to the nozzle longitudinal axis in an axial direction and connecting to a radially outer second channel surface of the fuel guiding channel, the tapering channel portion positioned between the end of the fuel guiding channel and the end of the second air guiding channel, the tapering channel portion ending at the end of the second air guiding channel; wherein, at a radially inner third surface of the fuel guiding channel, a concave curvature is provided via which an upstream obliquely radially inward oriented section of the third surface transitions into a section of the third surface that extends axially at the end of the fuel guiding channel; wherein the concave curvature of the third surface has a radius of maximally 15 mm.

Description

(1) The attached Figures illustrate possible embodiment variants of the suggested solution by way of example.

(2) Herein:

(3) FIG. 1A shows, on an enlarged scale and in sections, the area at a nozzle exit opening of a nozzle with a conically tapering channel portion between the end of a fuel guiding channel and an end of a second air guiding channel of the nozzle for avoiding non-stationary accumulations of fuel and fuel outlet flows at the end of the fuel guiding channel;

(4) FIG. 1B shows a possible further development of the embodiment variant of FIG. 1A in a view corresponding to FIG. 1A;

(5) FIG. 1C shows, in sections, an enlarged rendering of a further development of the channel portion of FIG. 1A;

(6) FIG. 2A shows an engine in which a combustion chamber with a nozzle according to FIG. 1 is used;

(7) FIG. 2B shows, in sections and on an enlarged scale, the combustion chamber of the engine of FIG. 2A;

(8) FIG. 2C shows, in a cross-sectional view, the general structure of the nozzle of FIG. 1 and the surrounding components of the engine in the installed state of the nozzle.

(9) FIG. 2A schematically illustrates, in a sectional view, a (turbofan) engine T in which the individual engine components are arranged in succession along a rotational axis or central axis M and the engine T is embodied as a turbofan engine. By means of a fan F, air is suctioned in along an entry direction at an inlet or an intake E of the engine T. This fan F, which is arranged inside a fan housing FC, is driven via a rotor shaft S that is set into rotation by a turbine TT of the engine T. Here, the turbine TT connects to a compressor V, which for example has a low-pressure compressor 11 and a high-pressure compressor 12, and where necessary also a medium-pressure compressor. The fan F supplies air to the compressor V in a primary air flow F1, on the one hand, and, on the other, to a secondary flow channel or bypass channel B in a secondary air flow F2 for creating a thrust. Here, the bypass channel B extends about a core engine that comprises the compressor V and the turbine TT, and also comprises a primary flow channel for the air that is supplied to the core engine by the fan F.

(10) The air that is conveyed via the compressor V into the primary flow channel is transported into the combustion chamber section BK of the core engine where the driving power 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 drives the rotor shaft S and thus the fan F by means of the energy that is released during combustion in order to generate the necessary thrust by means of the air that is conveyed into the bypass channel B. The air from the bypass channel B as well as the exhaust gases from the primary flow channel of the core engine are discharged via an outlet A at the end of the engine T. Here, the outlet A usually has a thrust nozzle with a centrally arranged outlet cone C.

(11) FIG. 2B shows a longitudinal section through the combustion chamber section BK of the engine T. Here, in particular an (annular) combustion chamber 3 of the engine T can be seen. A nozzle assembly group is provided for injecting fuel or an air-fuel mixture into a combustion space 30 of the combustion chamber 3. It comprises a combustion chamber ring R at which multiple (fuel/injection) nozzles 2 are arranged along a circular line about the central axis M. Here, the nozzle exit openings of the respective nozzles 2 that are positioned inside the combustion chamber 3 are provided at the combustion chamber ring R. Here, each nozzle 2 comprises a flange by means of which a nozzle 2 is screwed to an outer housing G of the combustion chamber 3.

(12) FIG. 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. Here, 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 during mounting is inserted through an access hole L through a combustion chamber head 31, through a heat shield 300 and a head plate 310 of the combustion chamber 3 up to the combustion space 30 of the combustion chamber 3, so that a nozzle exit opening formed at a nozzle main body 20 reaches all the way to the combustion space 30. The nozzle 2 further comprises a nozzle neck 21 which substantially extends radially with respect to the central axis M and inside of which a fuel supply 210 conveying fuel to the nozzle main body 20 is accommodated. Further formed at the nozzle main body 20 are a fuel chamber 22, fuel passages 220, heat shields 23 as well as air chambers for insulation.

(13) In addition, the nozzle main body 20 forms a (first) inner air guiding channel 26 extending centrally along a nozzle longitudinal axis DM and, positioned radially further outside with respect to the same, (second and third) outer air guiding channels 27a and 27b. These air guiding channels 26, 27a and 27b extend in the direction of the nozzle exit opening of the nozzle 2.

(14) Further, also at least one fuel guiding channel 25 is formed at the nozzle main body 20. This fuel guiding channel 25 is located between the first inner air guiding channel 26 and the second outer air guiding channel 27a. The end of the fuel guiding channel 25, via which fuel flows out in the direction of the air from the first inner air guiding channel 26 during operation of the nozzle 2, is located with respect to the nozzle longitudinal axis DM and in the direction of the nozzle exit opening in front of the end of the second air guiding channel 27a from which air from the second, outer air guiding channel 27a flows out in the direction of a mixture of air from the first, inner air guiding channel 26 and fuel from the fuel guiding channel 25.

(15) Usually, also swirling elements for swirling the air that is supplied via these are provided in the outer air guiding channels 27a and 27b (cf. FIG. 1). Further, the nozzle main body 20 also comprises an outer, radially inwardly oriented air guiding element 41 at the end of the third outer air guiding channel 27b. A sealing element 28 is also provided at the nozzle main body 20 at its circumference for sealing the nozzle 2 towards the combustion space 30. This sealing element 28 forms a counter-piece to a so-called burner seal 4. This burner seal 4 is floatingly mounted between the heat shield 300 and the head plate 310 to compensate for radial and axial movements between the nozzle 2 and the combustion chamber 3 and to ensure reliable sealing in different operational states.

(16) The burner seal 4 usually has a flow guiding element 40 towards the combustion space 30. In connection with the third outer air guiding channel 41 at the nozzle 2, this flow guiding element 40 ensures a desired flow guidance of the fuel-air mixture that comes from the nozzle 2, more precisely the swirled air from the air guiding channels 26, 27a and 27b, as well as the fuel guiding channel 25.

(17) In the nozzle 2 of FIG. 2C, which is a pressure-assisted injection nozzle, the ends of the second and third radially outwardly located air guiding channels 27a and 27b follow—with respect to the nozzle longitudinal axis DM and in the direction of the nozzle exit opening—the end of the fuel guiding channel 25 from which fuel is supplied to the air from the first inner centrally extending air guiding channel 26 during operation of the engine T. In order to avoid non-stationary accumulations of fuel and fuel outlet flows at this end of the fuel guiding channel 25 during operation of the engine T and to achieve an equalizing of the fuel feed or the fuel injection over time as well as space, a design of the nozzle end (of the end of the nozzle main body 20) is proposed which is geometrically improved in this regard. An embodiment variant of it is illustrated on an enlarged scale in FIG. 1.

(18) In the nozzle 2 shown in FIG. 1A, a tapering channel portion 9 with a shell surface 292b that extends in an inclined manner in the axial direction is formed between the end of the fuel guiding channel 25 and the end of the second air guiding channel 27a at the nozzle 2. Here, the inclined shell surface 292b of the channel portion 9 connects to a radially outer shell surface 291b of the fuel guiding channel 25. Here, the shell surfaces 291b and 292b extend at an angle to each other that is larger than 10° so as to define, via the shell surface 292b connecting to the fuel guiding channel 25, a “pre-film” surface for attachment of fuel, extending in the direction of the nozzle exit opening. The fuel guiding channel 25 thus transitions into the channel portion 9 which tapers off in the direction of the nozzle exit opening and thus towards an end of the second radially outwardly located air guiding channel 27a or that converges in the direction of the nozzle exit opening.

(19) Here, at the end of the nozzle 2, the fuel guiding channel 25 is formed with a radially inwardly angled channel section 251. This angled channel section 251 connects to a channel section 250 of the fuel guiding channel 25 that extends substantially in parallel to the nozzle longitudinal axis DM and that is bordered, corresponding to the cross-sectional view of FIG. 1A, by inner and outer shell surfaces 290a and 290b that extend in parallel to one another. While thus a radially inwardly located shell surface 291a of the connecting angled channel section 251 is guided up to a shell surface of the first air guiding channel 26, the opposite, radially outer shell surface 291b of the angled channel section 251 transitions into the shell surface 292b of the channel portion 9, which has a larger diameter as compared to the first, inner air guiding channel 26. In the present case, the transition between the fuel guiding channel 25 and the channel portion 9 in the area of the shell surfaces 291b and 292b is designed to be continuous and edge-free via a curvature that has a radius R.sub.PFO, here of maximally 2 mm.

(20) The (consistently) larger diameter of the channel portion 9 as compared to the diameter of the inner, first air guiding channel 26 results from a radial offset of the outer shell surface 292b of the channel portion 9 to an end of the shell surface of the first air guiding channel 26. Thus, the fuel guiding channel 25 is not completely guided up to a diameter of the first air guiding channel 26. Rather, at its widest position in the area of the end of the fuel guiding channel 25, the diameter of the channel portion 9 is larger than a diameter 2r.sub.inner of the first air guiding channel 26 at the end of the fuel guiding channel 25 by a distance 2Δr.sub.1. Thus, in the area of the end of the fuel guiding channel 25, the shell surface 292b of the channel portion 9 is offset radially outwards by a distance Δr.sub.1 to an end of the shell surface of the first air guiding channel 26. In the shown embodiment variant, the distance Δr.sub.1 is less than 0.8 mm, in particular less than 0.665 mm. For example, the distance Δr.sub.1 can be at least 0.2 mm and maximally 2 mm. However, in principle, Δr.sub.1 can also be less than 0.2 mm, or even zero.

(21) The channel portion 9 tapers in the direction of the nozzle exit opening over a length x.sub.PF. However, an offset to the end of the first air guiding channel 26 still remains. The shell surface 292b of the channel portion 9 is also radially offset in the area of the end of the second air guiding channel 27b and thus at the (rear, downstream) end of the channel portion 9 by a distance Δr.sub.2 (with 0≤Δr.sub.2<Δr.sub.1) to the shell surface of the first air guiding channel 26. Accordingly, while extending radially inward, the shell surface 292b of the channel portion 9 does not extend beyond a virtual extension of a radially outer terminal edge of the first air guiding channel 26. Here, the virtual extension of the radially outer terminal edge of the first air guiding channel 26 is shown in FIG. 1A over a reference axis RF. The diameter of the channel portion 9 is thus always larger than the diameter of the first air guiding channel 26 at the end of the fuel guiding channel 25. In the shown embodiment variant of FIG. 1A, a distance Δr.sub.2 is for example at least 0.1 mm, in particular 0.2 mm.

(22) The taper of the channel portion 9 is further chosen in such a manner that the shell surface 292b of the channel portion 29 extends at an angle α≤40° to the nozzle longitudinal axis DM. Through such a taper over a length of x.sub.PF of at least 1 mm, in particular of at least 2 mm, an even flow of fuel to the nozzle exit opening can be achieved during operation. Further, a spatial decoupling of local vibrations can be avoided due to an uneven flow-out of fuel and of a two-phase mixture of fuel and air at a radially outer trailing edge of the fuel guiding channel 25. Non-stationary accumulations of fuel and fuel outlet flows at the end of the fuel guiding channel 25 are also avoided. The fuel is then conveyed more evenly via the shell surface 292b of the channel portion 9 which then serves as a guide surface for a film of fuel, which results in a homogenous fuel drop distribution in the fuel-air mixture at the nozzle exit opening. A thus resulting spray with a small fuel drop diameter that is continuous over time in turn leads to the reduction of pollutants created during combustion in the combustion space 30. The length x.sub.PF can be limited to maximally 7 mm, for example. For example, x.sub.PF≥3 Δr.sub.1 applies.

(23) In contrast to the variant shown in FIG. 1, the distances Δr.sub.1 and Δr.sub.2 and the length x.sub.PF can also be chosen in a different manner, in particular depending on a predefined mass flow of fuel at certain predefined operating points of the engine T as well as the diameter 2r.sub.inner of the inner first air guiding channel 26. The length in x.sub.PF should for example be so long that local non-stationary effects due to the discharge of fuel from the fuel guiding channel 25 are spatially separated from a multiphase flow at a (atomizer) edge e.sub.ll. This edge e.sub.ll is formed at a transition of the shell surface 292b of the channel portion 9 and a radially inner shell surface of the second outer air guiding channel 27a. The edge e.sub.ll is further designed to be as sharp as possible to avoid local back flows at the tapered end of the channel portion 9. A wall section 29b of the nozzle main body 2 which, on the one hand, forms the shell surface of the channel portion 9 and, on the other hand, forms the radially inner shell surface of the second air guiding channel 27a, thus tapers off towards the edge e.sub.ll at the end of the channel portion 9 and of the second air guiding channel 27a. Hereby, a sharp-edged transition is formed between the shell surface 292b of the channel portion 9 and the inner shell surface of the second air guiding channel 27a.

(24) For avoiding back flows, a sharp-edged transition is also formed between the shell surface of the first air guiding channel 26 and the inner shell surface 291a of the fuel guiding channel 25 at the end of the fuel guiding channel 25. A wall section 29a of the nozzle main body 2 which, on the one hand, forms the inner shell surface 291a of the fuel guiding channel 25 and, on the other hand, forms the shell surface of the first air guiding channel 26 thus also tapers off towards an edge e.sub.l at the end of the fuel guiding channel 25 and of the first air guiding channel 26.

(25) Incidentally, it is of course not absolutely necessary that the end of the shell surface 292b of the channel portion 9 and thus the (end) edge e.sub.ll is located radially outside with respect to the reference axis RF. In one embodiment variant, the (end) edge e.sub.ll can be located radially further inside with respect to the radially inner (end-) edge e.sub.l of the fuel guiding channel 25, so that a value for Δr.sub.2 can be “negative”, that is, r.sub.inner>r.sub.outer applies, wherein 2 r.sub.outer corresponds to the diameter of the channel portion 9 at its nozzle-exit-side end (at the edge e.sub.ll). For example, in such an embodiment variant, the geometry in the area of the channel portion 9 is characterized by Δr.sub.1=0.2 mm, Δr.sub.2=0.1 mm and R.sub.PFO=1.0 mm, in a manner corresponding to the rendering of FIG. 1C that is enlarged in sections.

(26) In the further development of the embodiment variant of FIG. 1A that is shown in FIG. 1B, an (end) section of the fuel guiding channel 25 also connects downstream to the angled channel section 251 of the fuel guiding channel 25 extending axially in the direction of the nozzle exit opening. Here, a concave curvature is provided at the radially inner shell surface 291a of the fuel guiding channel 25 via which the angled and thus obliquely radially inwardly oriented section of the radially inner shell surface transitions into an axially extending section. In the present case, the concave curvature has a radius R.sub.Duct of maximally 15 mm and is located opposite the convex curvature at the radially outer shell surface 291b with the radius R.sub.PFO. An axial length of the axially extending, radial inwardly located end section of the fuel guiding channel 25 may for example only correspond to a fraction of the length x.sub.PF. For example, this length is smaller than 0.5 x.sub.PF.

(27) The radius R.sub.PFO can vary depending on the size of the curvature at the radially inner shell surface 291a and in particular the accompanying axial length of the axially extending, radially inwardly located end section of the fuel guiding channel 25 (that is tapering towards the edge e.sub.l at the end). If an axially extending radially inwardly located end section of the fuel guiding channel 25 and a concave curvature with a radius R.sub.Duct provided for the transition are present, with 0<R.sub.Duct≤15 mm, the radius R.sub.PFO of the convex curvature at the radially outer shell surface 291b is maximally 8 mm.

PARTS LIST

(28) 11 low-pressure compressor 12 high-pressure compressor 13 high-pressure turbine 14 medium-pressure turbine 15 low-pressure turbine 2 nozzle 20 nozzle main body 21 neck 210 fuel supply 22 fuel chamber 220 fuel passage 23 heat shield 24a, 24b air chamber 25 fuel guiding channel 250, 251 channel section 26 first air guiding channel 27a second air guiding channel 27b third air guiding channel 28 sealing element 290a, 290b, 291a, 291b shell surface 292b shell surface/guide surface 29a, 29b wall section 3 combustion chamber 30 combustion space 300 heat shield 31 combustion chamber head 310 head plate 4 burner seal 40 flow guiding element 41 air guiding element 9 channel portion A outlet B bypass channel BK combustion chamber section C outlet cone D diffuser DM nozzle longitudinal axis E inlet/intake e.sub.l, e.sub.ll edge F fan F1, F2 fluid flow FC fan housing G outer housing L access hole M central axis/rotational axis R combustion chamber ring RF reference axis r.sub.inner radius R.sub.Duct, R.sub.PFO radius S rotor shaft T (turbofan) engine TT turbine V compressor x.sub.PF length Δr.sub.1, Δr.sub.2 distance α angle