Patent Application
20180080655
This application claims priority to German Patent Application DE102016217876.8 filed Sep. 19, 2016, the entirety of which is incorporated by reference herein.
The invention relates to a combustion chamber shingle of a gas turbine combustion chamber as well as to a combustion chamber wall of a gas turbine combustion chamber, including the use of the combustion chamber shingle according to the invention.
Typical combustion chambers of gas turbines consist of an inner and an outer combustion chamber wall. Shingles are laterally attached at these combustion chamber walls, facing towards the interior space of the combustion chamber. These shingles protect the combustion chamber walls from the high temperatures that occur during the combustion process.
Arising here is the general problem of attaching the shingles at the combustion chamber wall in a suitable manner in such a way that they are secured in the long run during operation. For this purpose, the shingles are usually screwed to the combustion chamber by means of a wall fixation element. Such fixation elements may for example be configured in the form of stud bolts that are connected to the shingle.
In order to cool the shingles, the combustion chamber walls have impingement cooling holes through which cooling air is introduced into the intermediate space between the combustion chamber wall and the shingle. This air is discharged from the hot side of the shingle facing towards the interior space of the combustion chamber through the effusion cooling holes that are provided in the shingle. The cooling air that is [discharged] from the effusion cooling holes settles on the hot side of the shingle as a cooling air film, and causes it to be cooled.
It is known from the state of the art to provide the shingles with a shingle bolt, in one piece with the shingle. During the attachment of the shingles, the shingle bolt is guided through suitable recesses of the combustion chamber wall and screwed on from the outside. Strength tests have shown that material creeping occurs at the transition from the shingle to the shingle bolt or the securing bolt at the given temperatures. As a result, the service life of the shingle is considerably reduced as it may detach from the combustion chamber wall. Further, it has proven to be disadvantageous that cooling can be realized only to a limited extent in an area where the bolt is connected in one piece to the shingle, because large material accumulations are present in that location. Thus, this transitional area between the bolt and the shingle leads to thermal problems.
The following printed documents are referred to as the underlying state of the art:
What is known from EP 1 413 831 A1 is a construction in which the shingles are retained by hook-shaped elements. This construction requires an elaborate manufacturing and complex mounting process. A similar hook construction is also shown in EP 2 886 962 A1.
In EP 2 873 921 A1, a separate securing bolt is used that is inserted into a suspension device of the shingle. This construction also entails a considerable manufacturing and mounting effort.
In the construction that is known from EP 2 295 865 A2, it is provided that an attachment area is formed at a shingle, with a screw being screwed into it. Also in this construction, large material accumulations are present in the area of the attachment, which may lead to cooling problems.
EP 2 743 585 A1 shows a bolt which is connected in one piece to the shingle and in which the above-mentioned disadvantages may occur. A similar solution is also shown in EP 2 700 877 A2, wherein additional measures are provided for cooling the transition between the shingle and the bolt.
EP 2 738 470 A1 describes a solution in which the mixing air holes inside the combustion chamber shingle and the combustion chamber wall are used for screwing the shingle to the combustion chamber wall by means of an additional attachment element. Additional cooling air channels are formed for the purpose of cooling.
Thus, in the state of the art there is the general problem that the attachment of the bolt at the combustion chamber shingle can considerably reduce the service life of the total construction as a result of thermal loads.
The invention is based on the objective to create a combustion chamber shingle as well as a combustion chamber wall in which the disadvantages of the state of the art are avoided, and which facilitate a thermally optimized solution with a long service while at the same time having a simple structure and a simple, cost-effective manufacturability.
According to the invention, this objective is achieved by combinations of the features of the independent claims, with the respective subclaims showing further advantageous embodiments of the invention.
As for the combustion chamber shingle, it is provided according to the invention that it is configured in one piece with the securing bolt. However, the securing bolt additionally has a bolt disc that is connected in one piece to the securing bolt, namely in such a manner that the bolt disc has a distance to the combustion chamber shingle. The free end area of the securing bolt that extends from the bolt disc is provided with a thread.
The combustion chamber shingle according to the invention is characterized by a series of significant advantages. Thanks to the bolt disc it is achieved that the combustion chamber shingle does not directly abut the combustion chamber wall. Instead, the bolt disc forms a counter bearing which is supported against the combustion chamber wall and is braced by means of a nut that is screwed to the thread of the securing bolt. In this way, an intermediate space through which the cooling air can flow is created between the bolt disc and the combustion chamber shingle. This leads to an improvement of the cooling by means of the cooling air that is introduced into the intermediate space between the combustion chamber shingle and the combustion chamber wall.
It is particularly advantageous if the end area of the securing bolt that is provided with the thread has a larger diameter than the area of the securing bolt between the combustion chamber shingle and the bolt disc. This means that the securing bolt can have a considerably smaller diameter between the combustion chamber shingle and the bolt disc, so that less material accumulation is present in that area, which in turn leads to a reduction of the mass to be cooled. This results in a smaller thermal impingement, which in total leads to a longer service life of the combustion chamber shingle, because the material creeping processes as they are known from the state of the art either do not occur at all or occur only to a very limited extent.
According to the invention, the cross-section of the bolt disc can have a conical shape, so that the force transmission into the combustion chamber shingle is improved.
In an alternative or additional embodiment, the bolt disc can be configured in a dish-shaped manner so as to have a certain elasticity. Here, the attachment disc serves as a biasing spring for additionally securing the screw connection by means of the nut.
In order to minimize the heat transfer into the shingle and to maximize the cooled surface on the hot side it can be advantageous to provide the bolt with a smaller diameter at the transition to the shingle than at the thread area of the bolt, as has been described. In addition, it is possible to select the thickness of the bolt disc in such a manner that the bolt disc has a smaller thickness at the radially outer area than at the radially inner area.
All this leads to improved cooling options of the shingle in the attachment area.
As for the structure of the combustion chamber wall of a gas turbine combustion chamber, it is provided according to the invention that the nut for attaching the securing bolt abuts the combustion chamber wall. The result is a load path that extends through the free area of the securing bolt, through the nut, through the edge area of the associated recess of the combustion chamber wall, and through the bolt disc. Thus, the attachment area of the securing bolt at the combustion chamber shingle is not subjected to loads due to the screw connection. What results in this manner is a considerable reduction of the mechanical load in this area. This leads to reduced material creeping, and thus to a reduced susceptibility to failure.
In addition, it can be advantageous to arrange a separate washer between the nut and the combustion chamber wall. The washer may for example serve for compensating dimensional measurements, and for providing a sufficient contact surface of the nut.
To additionally cool the area of the screw connection of the combustion chamber shingle, it can be advantageous if additional cooling air recesses are provided in the bolt disc and/or in the washer.
Further, the washer can be provided with a ring flange that surrounds the securing bolt and extends through the recess of the combustion chamber wall through which the securing bolt is guided. This leads to a simplified mounting process and takes into account the dimensional deviations of the recesses of the combustion chamber wall.
The external diameter of the bolt disc is substantially equal to the external diameter of the washer. However, other dimensioning options can also be advantageous.
In the following, the invention will be described based on an exemplary embodiment in connection with the drawing. Herein:
The gas turbine engine 10 according to
The medium-pressure compressor 13 and the high-pressure compressor 14 respectively comprise multiple stages, of which each has an arrangement of fixedly arranged stationary guide vanes 20 that extends in the circumferential direction, with the stationary guide vanes 20 being generally referred to as stator vanes and projecting radially inward from the core engine shroud 21 through the compressors 13, 14 into a ring-shaped flow channel. Further, the compressors have an arrangement of compressor rotor blades 22 that project radially outward from a rotatable drum or disc 26, and are coupled to hubs 27 of the high-pressure turbine 16 or the medium-pressure turbine 17.
The turbine sections 16, 17, 18 have similar stages, comprising an arrangement of stationary guide vanes 23 projecting radially inward from the housing 21 through the turbines 16, 17, 18 into the ring-shaped flow channel, and a subsequent arrangement of turbine blades/vanes 24 projecting outwards from the rotatable hub 27. During operation, the compressor drum or compressor disc 26 and the blades 22 arranged thereon as well as the turbine rotor hub 27 and the turbine rotor blades/vanes 24 arranged thereon rotate around the engine axis 1.
At its free end area, the securing bolt 25 is provided with a thread 31 onto which a nut 33 can be screwed.
At a distance and in parallel to the surface of the combustion chamber shingle, the bolt has a bolt disc 30 configured in one piece with the same. In the shown exemplary embodiment, the bolt disc 30 is configured as a circular disc, but it can also have any other shape, for example it can be polygonal or rectangular.
As shown in
Reference sign 32 indicates a combustion chamber wall that is provided with a recess. The securing bolt 25 is guided through this recess. In addition, a washer 34 is inserted, with the nut 33 being supported against it. The washer 34 has a ring flange 35 that extends into the free hole space of the combustion chamber wall 32, and can for example serve for centering the combustion chamber shingle 29, or for securing its position.
Thus, the present invention refers to a concept for attaching combustion chamber shingles at a combustion chamber wall. As mentioned, the combustion chamber shingles protect the combustion chamber housing from the high temperatures that occur inside the combustion chamber during the combustion of kerosene. In order to obtain a sufficiently long service life of the shingles, a protective ceramic layer is usually applied to the hot side of the combustion chamber shingle. Further, cooling air holes (effusion holes) are drilled through the shingle in order to create a cooling film of cold air on the hot side of the shingle. Here, the invention in particular relates to the screw connection of the combustion chamber shingles and to the optimization of the load path. Among other things, this results in the following advantages:
Because the load path to the screw connection is realized via the securing bolt, the bolt disc, the combustion chamber wall, the nut, and again through the securing bolt, this load path is shortened considerably as compared to previously known constructions.
Through the optimized load path, the highly stressed structural components that serve for attaching the combustion chamber shingle, are decoupled from the shingle surface. This results in considerably lower temperatures in the highly stressed structural components, which leads to a longer service life and provides a significant protection from failure.
As mentioned, the attachment of the combustion chamber shingle at the securing bolt is realized with a smaller diameter than the securing bolt itself, since now only the loads that occur during operation have to be transferred as a result of the thermal expansion. The load path to the screw connection of the combustion chamber shingle is thus decoupled from this transitional area of the securing bolt to the combustion chamber shingle.
Through the construction according to the invention, it is facilitated that additional cooling air slits (not shown) are formed in the bolt disc or the washer, in order to provide a further cooling and to lower the overall temperature.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 217 876.8 | Sep 2016 | DE | national |
