Patent Application
20170023250
This application claims priority to German Patent Application No. 10 2015 213 629.9 filed on Jul. 20, 2015, the entirety of which is incorporated by reference herein.
The invention relates to a covering part for a combustion chamber of a gas turbine as well as a combustion chamber assembly group for a gas turbine with such a covering part, which is provided in the area of a combustion chamber head.
A generic covering part is configured and provided for guiding a fluid flow downstream of a diffuser of the gas turbine at least partially into a flow area outside of a combustion space of the combustion chamber in order to cool a combustion chamber wall that delimits the combustion space. Thus, such a covering part is provided for example in an annular manner in the area of a combustion chamber head in order to divide a primary air flow and, for one thing, guide air via a combustor dome into the combustion space and, for another, past the combustion space in order to cool the combustion chamber walls. In the context of gas turbine engines, such a covering part is also referred to as an inflow or inlet hood, and also as a “cowling”.
Such a covering part if fixated via at least one mounting edge at a combustion chamber wall of the combustion chamber by means of a separate attachment element, for example in the form of a bolt. For this purpose, at least one attachment site for an attachment element is provided at the mounting edge, for example in the form of a bore. Because the covering part is manufactured separately and can subsequently be fixated to a combustion chamber wall, it can be manufactured in a comparably cost-effective manner. Thus, such a covering part is in particular different from solutions as they are known from the state of the art, in which a covering part is formed in one piece with a combustion chamber wall, as is for example shown in DE 100 48 864 A1 and DE 196 43 028 A1.
In covering parts that are fixated at a combustion chamber wall as a separate structural component, it is preferred in practice, with a view to a simplified mounting and to avoiding leakages, that a section of the [mounting edge] to which the attachment element is attached extends substantially in parallel or perpendicular to a turbine axis. Thus, a mounting edge of the covering part that is provided for positioning at least one bolt head or a nut extends preferably in a planar manner along a lateral surface of a circular-cylindrical section of the covering part. Thus, the mounting edge can be formed in a circular-cylindrical manner in order to fixate the covering part at a combustion chamber wall via multiple attachment elements that are arranged at a distance from each other along the circumference. Such covering parts with corresponding mounting edges and screws or threaded bolts provided for fixating are known from EP 0 550 953 A1, EP 1 340 941 B1 and US 5,924,288 A, for example.
However, it has been observed in practice that undesired flow interferences may occur in the area of the screw or bold heads of the attachment elements via which the covering part is fixated at the combustion chamber wall. Thus, return flows, turbulences, and/or flow separation and consequently the possibility of relatively large pressure losses may occur in that area, which have a direct negative effect on the fuel consumption. Besides, this may also have a negative impact on the surround-flow around the combustion chamber wall and thus possibly on the cooling of the combustion chamber wall. In particular when it comes to canted combustion chambers, i.e. combustion chambers having a central axis with a comparably large angle (larger than 10°) with respect to the horizontal and/or vertical line, the previously mentioned negative effects in the area of the mounting edges of the covering part are increasingly observed.
Thus, it is an objective of the invention to improve a covering part and a combustion chamber assembly group with such a covering part in this respect and to avoid undesired flow interferences in the area of the fixation of the covering part.
This objective is achieved with a covering part as described herein.
What is suggested here according to the invention is a covering part for a combustion chamber of a gas turbine, which is
Thus, an aerodynamically more advantageous geometry is formed by means of the at least one guiding element, guiding the partial flow of the fluid flow for example around a screw joint and in particular around a bolt head that protrudes at the mounting edge, and in this way in particular reduces the risk of any undesired turbulences occurring in the area where the covering part is connected to the combustion chamber wall.
By using a guiding element, which can guide the partial flow of the fluid flow in a targeted manner over and above that part of an attachment element that protrudes at the mounting edge, or over and above multiple such parts of multiple attachment elements, the contact surface for the attachment element formed by the mounting edge can still extend in a manner perpendicular or in parallel to the turbine axis. Thus, the mounting edge can for example still be formed so as to extend in a circular-cylindrical manner around a turbine axis and so as to protrude in parallel to the turbine axis, so that the screws or bolts that are necessary for fixating the covering part can then be mounted in a perpendicular manner and thus radially with respect to the turbine axis.
In order to be able to effectively guide a partial flow of the fluid flow over and above the part of the attachment element that protrudes at the mounting edge by means of the at least one guiding element, it is provided in an embodiment variant that the at least one guiding element extends at least across a section of the mounting edge. At that, the guiding element preferably extends in particular over and above that section or those sections of the mounting edge in which an attachment site or multiple attachment sites are provided for the attachment elements that are necessary for fixating the covering part.
In order to at least partially cover a part of an attachment element that is protruding at the mounting edge, for example a screw or bolt head, by means of the guiding element and at the same time still achieve a simple mounting and in particular simple attachment of the attachment element in such a variant, the guiding element can have one or multiple recesses. Here, the size of a recess is dimensioned in such a manner that the attachment element can be passed through the same. An attachment means that engages at the disassembly edge can then be accessed through a recess of the guiding element and/or an attachment element that is provided for the purpose of fixating the covering part can be guided towards the mounting edge so as to fixate the covering part. The covering part including the guiding element provided thereat is thus for example arranged at the combustion chamber wall, and subsequently a screw or a threaded bolt is inserted through respectively one recess and then screwed on from the other side with a nut.
The at least one guiding element can principally be fixated as an additional component at the covering part. Alternatively, the at least one guiding element is formed by a section of the covering part and can be formed at the covering part.
In addition, it is provided in a further development that the mounting edge is also formed in one piece with the guiding element. Here, the mounting edge can be bent with respect to a section of the covering part that forms the guiding element, so that the section of the covering part that forms the guiding element is positioned opposite the mounting edge. In such an exemplary embodiment, the covering part is for example formed in an annular manner with a circumferentially bent mounting edge, which abuts the attachment section of the combustion chamber wall in a planar manner in a state where it is mounted according to the intended use.
Then, in an exemplary embodiment, the heads of the attachment elements that are provided for fixating the covering part at the attachment section of the combustion chamber wall and that are inserted through recesses in the guiding element are present in a mounting channel that runs all the way around the circumference after having been mounted according to the intended use. At the radially inner side, this mounting channel is delimited by the mounting edge and at a radially outer side by the guiding element.
In particular in such an embodiment variant, the mounting edge can be bent by at least 160°, preferably by approximately 180°, with respect to an (edge) section of the covering part that forms the guiding element.
In one embodiment variant, at least one additional guiding element can be provided at the covering part, bridging a gap that is present between the guiding element and the adjacent combustion chamber wall in a state of being mounted according to the intended use of the covering part. Thus, an additional flow optimization is achieved through the additional guiding element. Due to the existing gap, turbulences and/or return flows are avoided downstream of the guiding element.
The additional guiding element can be welded to the covering part, for example at a downstream rear area of the guiding element.
In one embodiment variant, the covering part is provided for fixating at an inner as well as an outer combustion chamber wall, which together form the combustion space. Consequently, what is required are not two inner and outer covering parts extending concentrically with respect to each other in the area of the combustion chamber head. But rather, in this embodiment variant, for example an annular covering part is provided that is fixated at the inner and outer combustion chamber wall, and thus guides a part of the cooling flow coming from the diffuser into a radially outer as well as into a radially inner flow area outside of the combustion space so as to cool the combustion chamber. At a front side of the covering part that is facing towards the diffuser, multiple inflow openings are provided, so that air can also be guided into the combustion space.
In one embodiment variant, in which the covering part has to be fixated at the outer as well as at the inner combustion chamber wall, also two additional guiding elements can provided, of which a first additional guiding element bridges a first gap between an outer guiding element and the adjacent outer combustion chamber wall, and a second additional guiding element bridges a gap between an inner guiding element and the adjacent inner combustion chamber wall.
Independently of whether one or two additional guiding elements are used, it is preferable that an additional guiding element is formed in an annular manner and thus extends over the entire (outer or inner) circumference of the covering part.
Generally, it can be provided that the covering part does not only guide a part of the fluid flow coming from the diffuser into the direction of an outer and/or inner flow area outside of the combustion space. Rather, such a covering part can usually also partially guide a fluid flow coming from the diffuser into the direction of a combustor dome via a correspondingly embodied (inner) edge and/or a correspondingly embodied (inner) opening in order to create a flammable fuel-air-mixture inside the combustion space.
What is further suggested is a combustion chamber assembly group for a gas turbine where a covering part according to the invention is used, comprising
Here, the mounting edge can extend at least in the area of the attachment site for an attachment element in a manner substantially perpendicular or in parallel to a turbine axis so as to facilitate the manufacture of the mounting edge as well as the attachment of the attachment element.
In one embodiment variant, the covering part is connected, via a single attachment element in the area of the mounting edge of the covering part, to a separate combustion chamber head plate at which a fuel nozzle for injecting fuel into the combustion space is supported, as well as to a combustion chamber wall. Thus, ultimately three separate structural components of the combustion chamber assembly group are fixedly connected to each other by means of the single attachment element. For this purpose, the said structural components preferably respectively form a cylindrical edge with multiple recesses, perforations or bores through which a threaded bolt may be passed if they are aligned with each other. A covering part according to the invention and/or a combustion chamber assembly group according to the invention can be used in a gas turbine engine, for example.
Other advantages and features of the invention will become clear in the following description of exemplary embodiments based on the Figures.
In order to, on the one hand, guide the fluid flow coming from the diffuser into the combustion space 11, and, on the other hand, past the combustion space into the inner and outer flow areas 12a and 12b, a covering part 4 is provided in the area of the combustion chamber head plate 3. This covering part 4 is bulged in a convex manner in the direction of the diffuser and forms a combustion chamber head that is arranged in front of the combustion chamber head plate 3.
The covering part 4 is fixated via multiple screwed connections at the two combustion chamber walls 1a and 1b. Attachment elements in the form of (threaded) bolts 5 and nuts 6 are respectively provided for screwing the covering part 4 to the combustion chamber outer wall 1a as well as to the combustion chamber inner wall 1b. At that, the individual bolts 5 are arranged at a distance from each other respectively along a radially outer and a radially inner circumference of the annular covering part 4, so that the covering part 4 is fixated at the combustion chamber walls 1a and 1b. Here, each bolt 5 is inserted, on the one hand, through a bore in a mounting edge 40a or 40b, and, on the other hand, through a bore or opening in an axially projecting attachment section 10a or 10b of the respective combustion chamber wall 1a or 1b, as well as through a bore or opening in an attachment edge 30a or 30b of the combustion chamber head plate 3. A nut 6 is then screwed onto the threaded section of a bolt 5 that is respectively pinned trough the three mentioned components in order to connect the covering part 4 to the combustion chamber walls 1a, 1b and the combustion chamber head plate 3 in a fixated manner.
As can be seen from the frontal view of
Via the convex bulge of the covering part 4 between its two mounting edges 40a and 40b, a fluid flow that is impinging thereon is guided in a partially targeted manner into the two flow areas 12a and 12b to cool the combustion chamber walls 1a and 1b. The mounting edges 40a and 40b are also formed in a cylindrical manner with respect to the engine axis T and thus define locating surfaces for being placed at the corresponding attachment section 10a or 10b of a combustion chamber wall 1a or 1b that extends in parallel to the engine axis T. The result is a comparably strong offset between the convexly bulged front side of the covering part 4 and the respective mounting edge 40a or 40b, as well as the bolt head of a bolt 5 that is protruding therefrom. Due to this fact, especially in the area of the respective bolt 5 and thus in the transitional area between the covering part 4 and a combustion chamber wall 1a or 1b, undesired turbulences, return flows or flow separation may occur, which in turn may lead to high pressure losses and thus to increased fuel requirements.
As is illustrated in
In a first embodiment variant according to the invention as it is illustrated in the
Here, a section formed by a guiding element 42a or 42b, having an outer or an inner guide surface 420a or 420b for guiding the fluid flow, is positioned directly opposite the planar mounting edge 421a or 421b. Here, it is respectively ensured by a guiding element 42a, 42b with its guide surface 420a or 420b that the flow flows in a targeted manner over and beyond the bolt head that projects in an elevated manner from the respective mounting edge 421a or 421b, without the bolt head being positioned directly in the flow direction. Thus, by providing a guiding element 42a or 42b at the covering part 4, any interference of the fluid flow is avoided in the flow areas 12a and 12b in the area of the screw joints of the covering part 4.
At that, the covering part 4 that is formed according to the invention and that is preferably manufactured in a cost-effective manner from sheet metal is also easy to mount. Thus, the mounting edges 421a and 421b that extend concentrically with respect to each other are respectively formed in a circular-cylindrical manner at the covering part 4 and thus form a locating surface for fixating the covering part 4 at the combustion chamber outer wall 1a and the combustion chamber inner wall 1b that extends substantially in parallel to the engine axis T. Thus, the individual bolts 5 can be inserted and screwed on substantially perpendicularly to the engine axis T. In order to be able to unproblematically attach the individual bolts 5 after the covering part 4 has been arranged at the combustion chamber walls 1a and 1b, each of the guiding elements 42a, 42b has multiple recesses 43a and 43b for the bolt 5 along their circumference at their respective guide surfaces 420a or 420b. A bolt 5 can be inserted through each of these preferably circular recesses 43a and 43b, and its bolt head becomes accessible for a tool so as to fixate the covering part 4. In the cross-sectional view of
In the present case, the guide plate 8 is welded to the covering part 4 in the area of the downstream, rear area of the outer guiding element 42a through a welding seam 80. However, alternatively the guide plate 8 can also be screwed on, for example.
Further, it can be provided in an alternative embodiment variant that the guide plate 8 is not formed so as to run all the way around the outer circumference, and thus not in a circular-cylindrical manner. Instead, it would also be conceivable to provide a guide plate 8 only locally, for example adjacent to and downstream of a recess 43a. In this case, such a guide plate 8 consequently extends only across a fraction of the circumference of the covering part 4, so that multiple individual guide plates 8 can be provided at the covering part 4.
Principally, the guide plate 8 can also be embodied in a conical manner. Alternatively or additionally, a (further) guide plate 8 can also be provided in the area of the transition between the radial inner guiding element 42b and the combustion chamber inner wall 1b.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 213 629.9 | Jul 2015 | DE | national |
