Patent Application
20190093896
The invention relates to a nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle exit opening of the nozzle.
An (injection) nozzle for a combustion chamber of an engine, in particular for an annular chamber of a gas turbine engine, comprises a nozzle main body that has a nozzle exit opening and that, in addition to a fuel guiding channel for conveying fuel to the nozzle exit opening, has multiple (at least two) air guiding channels for conveying air intermixed with fuel to the nozzle exit opening. A nozzle usually also serves for swirling the supplied air, which, intermixed which the supplied fuel, is subsequently conveyed into the combustion chamber at the nozzle exit opening of the nozzle. For example, multiple nozzles may be grouped together in a nozzle assembly group that comprises multiple nozzles arranged next to each other, usually along a circular line, for introducing fuel into the combustion chamber.
In nozzles with multiple air guiding channels and at least one fuel guiding channel as they are known from the state of the art, for example from U.S. Pat. No. 9,423,137 B2, it is provided that a first air channel extends along a nozzle longitudinal axis of the nozzle main body and a fuel guiding channel is positioned radially further outwards than the first air channel with respect to the nozzle longitudinal axis. In that case, it is additionally provided that at least one further air channel is positioned radially further outwards than the fuel guiding channel with respect to the nozzle longitudinal axis. Here, one end of the fuel guiding channel at which the fuel form the fuel guiding channel flows out in the direction of the air from the first air guiding channel is typically located—with respect to the nozzle longitudinal axis and in the direction of the nozzle exit opening—in front of the end of the second air channel from which the air then flows out in the direction of a mixture of air from the first air channel and fuel from the fuel guiding channel. What is further provided in the state of the art and for example also provided in U.S. Pat. No. 9,423,137 B2 is to provide such a nozzle with a third air channel, with its end, which may also be displaced radially outwards, following the end of the second air channel in the axial direction.
The nozzle is positioned at the combustion chamber via a burner seal that seals the nozzle towards the combustion space of the combustion chamber. Here, the burner seal is usually floatingly mounted at a head plate of the combustion chamber to compensate for radial and axial movements between the nozzle and the combustion chamber and to ensure a reliable sealing effect in different operating states.
For guiding the fuel-air mixture provided by the nozzle, the burner seal often has a flow guiding element at the combustion space side. However, due to the axial displaceability of the nozzle relative to the burner seal and its flow guiding element, here the aerodynamic conditions vary depending on the operational state of the engine. Also, a radial distance between the nozzle and the burner seal, which has to be provided due to the construction, renders it more difficult to achieve an exactly predefined guidance of the fuel-air mixture via the flow guiding element of the burner seal. Both above-mentioned aspects influence the development of undesired soot emissions.
Against this background, there is the objective to provide a combustion chamber assembly group that is improved in this regard and that comprises a nozzle for providing a fuel-air mixture.
This objective is achieved through a nozzle of claim 1.
What is proposed according to the invention is a nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle exit opening of the nozzle, wherein the nozzle comprises the nozzle main body that comprises the nozzle exit opening and that extends along a nozzle longitudinal axis. Here, the nozzle main body further comprises at least the following:
Now an extension for guiding the fuel-air mixture extending in the axial direction with respect to the nozzle longitudinal axis is provided at the air guide element of the at least one further air channel. Here, the axial direction along which the extension extends is oriented towards a combustion space of the combustion chamber when the combustion chamber assembly group comprising the nozzle is arranged at a combustion chamber according to the intended use. Thus, the axial extension is located inside the combustion space and extends in the flow direction of the fuel-air mixture to be provided if the nozzle is arranged at the combustion chamber according to the intended use.
In a nozzle according to the invention, it is thus provided that the nozzle main body is formed with an extension for guiding the fuel-air mixture that is provided at the nozzle exit opening in the area of the air guide element of the at least one further (in the case of multiple air guiding channels of the radially outermost) air channel. Thus, the axial extension is configured and provided for guiding the created mixture of the fuel from the fuel guiding channel and the air from the first, inner air channel as well as the at least one further air channel. While thus the air guide element of the at least one further air channel is configured and provided for guiding air from the at least one further air channel, in particular for deflecting the flowing and usually swirled air with a radially inwardly oriented directional component, the axial extension is configured and provided for guiding the created fuel-air mixture. In this way, a mixture guidance is integrated in the nozzle, whereby any flow elements at the combustion-space side can be omitted at a burner seal via which the nozzle is positioned at the combustion chamber. In this way, the burner seal can be limited to its sealing function, and can be embodied without aerodynamic elements that influence the flow. By integrating the mixture guidance at the nozzle itself, any axial displacement of the nozzle and the burner seal relative to each other occurring as a result of operation does not have any negative influences on the guidance of the fuel-air mixture.
In an exemplary embodiment, the extension is formed in a tubular manner. In that case, the extension may for example be embodied in the kind of a tube piece at the combustion-space side end of the nozzle main body. In particular, the extension can be formed or molded at the nozzle main body as a tubular end piece.
In an exemplary embodiment it is provided that the extension extends in the axial direction with a length that is less than 3.5 times a height of the at least one further air channel and/or that is less than 3.5. times a height of a swirling element provided in the at least one further air channel. In this embodiment variant, given a height H of the at least one further air channel or of the swirling element, the following thus applies to a length l5 with which the extension extends in the axial direction: l5≤3.5 H. A corresponding geometric correlation between the length of the axial extension and the height of the at least one further air channel and/or of a swirling element provided in this air channel has proven to be advantageous for influencing the flow.
Alternatively or additionally, it can be provided that the air guide element of the at least one further air channel has a section (which is hollow and is passed by air from the air channel during operation of the engine) at which an inner diameter defined by the air guide element and thus the cross-sectional surface of the nozzle exit opening which is passable by a flow is minimal, and the extension—measured from a first reference point at this section and at the location of the minimal inner diameter—extends in the axial direction up to a second reference point that is located at a certain distance from the first reference point. Here, it may for example be provided that the distance between the first reference point and the second reference point that is measured along the nozzle longitudinal axis
As for the distance I between the first reference point at the minimal inner diameter of the air guide element and the second reference point that is located downstream thereto, the following correspondingly applies for a height H of the at least one further air channel or of the swirling element provided therein: H≤I≤3.5 H.
In one embodiment variant, a radially outwardly located lateral surface of the extension connects to a radially outwardly located lateral surface of the air guide element. This in particular includes that the air guide element and the extension have substantially or exactly the same outer diameter. Thus, through this extension, a maximal outer diameter of the nozzle is enlarged at its end that projects into the combustion space in the mounted state according to the intended use.
Alternatively or additionally, an inner lateral surface of the extension connects to an inner lateral surface of the air guide element of the at least one further air channel in the axial direction. An inner lateral surface of the air guide element thus transitions into the inner lateral surface of the extension without any steps or without any projection or recess, for example. In this way, the lateral surfaces of the extension and of the air guide element continuously transition into each other in such an embodiment variant.
In one embodiment variant, the extension has at least two sections succeeding each other in the axial direction and having different inner diameters. This for example includes that a first section of the extension with an inner diameter which remains constant in the axial direction (along the nozzle longitudinal axis) is provided upstream of a second section, with the latter having a different inner diameter that be increasing up to the end of the extension, if necessary. Here, a continuous widening of the opening that is passed by the flow can be provided in the second section.
In a further development, a length of a second (end-side) section measured in the axial direction and having a larger and/or increasing inner diameter in the axial direction is considerably smaller than a corresponding (axial) length of the first section. For example, the length of the second downstream, shorter section represents only a fraction of the length of the first section.
Alternatively or additionally, an inner diameter (of the nozzle exit opening) can increase continuously or at least with one step in the axial direction at least at one section of the extension. Thus, this variant in particular includes the previously described variant in which two sections with different inner diameters are provided. But this also includes variants in which not only a section of the extension, but the extension itself has an inner diameter that increases continuously in a diffuser-like manner. In particular, it can be provided that the at least one section of the extension or the extension itself has an inner lateral surface that extends in a manner pointing radially outwards with respect to the nozzle longitudinal axis and/or that is concavely curved. For example, in one exemplary embodiment, the inner lateral surface of the extension defines a (nozzle exit) opening for the fuel-air mixture widening in the shape of a truncated cone. With regard to the flow guidance, where appropriate, an additionally provided widening of the (nozzle exit) opening defined by the extension can be provided, in particular at an end of the extension that is located in the axial direction.
In contrast to the previously explained embodiment variants, in one embodiment variant it can also be provided that the extension has a constant inner diameter in the axial direction.
A further aspect of the suggested solution relates to the provision of a combustion chamber assembly group, with a burner seal that comprises a bearing section having a passage opening and extending along the nozzle longitudinal axis, and with a nozzle that is positioned inside the passage opening of the bearing section. In that case, the nozzle also here has an extension for guiding the fuel-air mixture extending in the axial direction.
Here, it is provided in one embodiment variant that the extension of the nozzle projects in the axial direction (which is oriented to a combustion space of the combustion chamber if the combustion chamber assembly group is arranged at a combustion chamber according to the intended use) beyond the bearing section. Thus, the guidance of the fuel-air mixture that is provided at the nozzle exit opening in the direction of the combustion space is realized exclusively by means of the nozzle and its axial extension.
In particular against this background, it can be provided in one embodiment variant that the burner seal is formed without flow guiding elements (at the combustion-space side). The burner seal is thus limited to its sealing function and is not designed for an aerodynamic function. In that case, the function of the flow guidance of the fuel-air mixture is taken over exclusively or at least predominantly by the nozzle with its axial extension.
Moreover, an engine with at least one nozzle according to the invention or a combustion chamber assembly group according to the invention is also provided within the scope of the solution according to the invention.
The attached Figures illustrate possible embodiment variants of the suggested solution by way of example.
Herein:
The air that is conveyed via the compressor V into the primary flow channel is transported into the combustion chamber section BKA 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.
In addition, the nozzle main body 20 forms a (first) inner air channel 26 extending centrally along a nozzle longitudinal axis DM and, positioned radially further outside with respect to the same, a (second and third) outer air guiding channel 27a and 27b. These air guiding channels 26, 27a and 27b extend in the direction of the nozzle exit opening of the nozzle 2.
Further, also at least one fuel guiding channel 26 is formed at the nozzle main body 20. This fuel guiding channel 25 is located between the first inner air channel 26 and the second outer air 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 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 channel 27a from which air from the second, outer air channel 27a flows out in the direction of a mixture of air from the first, inner air channel 26 and fuel from the fuel guiding channel 25.
Swirling elements 270a, 270b for swirling the air supplied through the air guiding channels 27a and 27b are provided in the outer air guiding channels 27a and 27b. Further, the nozzle main body 20 also comprises an outer, radially inwardly oriented air guide element 271b at the end of the third outer air channel 27b. In the nozzle 2, which may e.g. be 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 channel 26 during operation of the engine T, according to
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 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.
The burner seal 4 usually has a flow guiding element 40 towards the combustion space 30. In connection with the third outer air channel 27b at the nozzle 2, this flow guiding element 40 ensures a desired flow guidance of the fuel-air mixture that results 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.
In an embodiment of a burner assembly group according to
This problem is remedied by the suggested solution, for which different embodiment variants are shown in the
Here, it is respectively provided that an extension 5 is provided at the air guide element 271b of the outermost, third air channel 27b, extending in the axial direction in order to guide the resulting fuel-air mixture in the direction of the combustion space 30. This extension 5, which may for example be formed or molded integrally at the nozzle main body 20, respectively projects beyond a bearing section 41 of the burner seal 4 at the combustion chamber side. The passage opening through which the nozzle 2 is positioned at the burner seal 4 is provided in this bearing section 41. By thus guiding the fuel-air mixture through the nozzle-side extension 5 in the direction of the combustion space 30 at the nozzle exit opening, the burner seal 4 does no longer take over an aerodynamic function. The burner seal 4 now only serves the purpose of sealing, and is correspondingly formed without a flow guiding element 40.
In particular in the nozzle 2 of
Further, the axial expansion of extension 5 is respectively dimensioned in such a manner that other geometric conditions having proven to be advantageous are met. Thus, for guiding the air flowing out of the air channel 27b radially inwards, the air guide element 271b of the third air channel 27b defines an area with a minimal inner diameter D1 and thus a minimal cross-sectional surface of the nozzle exit opening through which the flow passes. A distance I of a reference point E1 at the location of this minimal inner diameter D1 to a further reference point E2 located in the axial direction and marking the end of the extension 5 is now dimensioned such that the following applies: H≤I≤3.5≤H.
In particular the extension 5 of the nozzle 2 shown in
While in the embodiment variant of
In contrast, in the variants of
In the variant shown in
In the embodiment variant of
In contrast to the embodiment variant of
In the shown embodiment variants of
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 217 328.9 | Sep 2017 | DE | national |
