Patent Application
20110192137
This application which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2010 007 272.9-14, filed Feb. 8, 2010, the entire disclosure of which is herein expressly incorporated by reference.
The invention relates to a method for manufacturing a regeneratively cooled nozzle extension of a rocket combustion chamber, the nozzle extension comprising a first wall and a second wall which are arranged coaxially to each other and between which a number of cooling channels is configured. The cooling channels are laterally delimited by cooling channel webs. In the method, the first and the second wall are connected to each other by a positive fit by cooling channel webs of the first wall engaging with corresponding recesses of the second wall for forming the positive fit.
The invention also relates to a regeneratively cooled nozzle extension for a rocket combustion chamber, the nozzle extension comprising a first and a second wall which are arranged coaxially to each other and between which a number of cooling channels is configured. The cooling channels are laterally delimited by cooling channel webs. In the nozzle extension, the first and the second wall are connected to each other by a positive fit by cooling channel webs of the first wall engaging with corresponding recesses of the second wall for forming the positive fit.
Nozzle extensions of rocket combustion chambers represent thermally highly loaded components. For reducing the thermal load, the nozzle extensions are cooled. This takes place primarily by incorporating cooling channels through which at least one fuel component flows to extract heat from the wall of the nozzle extension. The heated fuel component or components is or are, respectively, fed at the outlet from the cooling channels to the drive system for the final reaction in the rocket combustion chamber. Alternatively, the fuel components can be ejected via separate systems to generate a thrust.
From the prior art, different methods for manufacturing regeneratively cooled extension nozzles comprising cooling channels are known.
U.S. Pat. No. 6,467,253 B1 discloses a method in which segments of the nozzle extension each of which consist of an inner and an outer wall connected to each other by a positive fit by cooling channel webs of the inner wall engaging with corresponding recesses of the outer wall for forming the positive fit. A plurality of the segments is connected to each other via a welded joint to form a rotationally symmetric nozzle extension. Due to the construction, the cooling channels have a small cross-section here, which limits the cooling capacity.
U.S. Pat. No. 6,789,316 B2 discloses a method in which Y-shaped profile members are welded together to form corresponding cooling channels. This requires a nozzle extension manufactured from a plurality of such profile members, which is a costly manufacturing method.
US 2006/0213182 A1 discloses arranging an inner wall having cooling channel webs and an outer wall having a smooth inner side on top of each other and to interconnect them by brazing.
Manufacturing methods using brazing and welding joints are characterized by a very high production-related expenditure.
Exemplary embodiments of the present invention provide a method by means of which a regeneratively cooled nozzle extension of a rocket combustion chamber can be manufactured in a simpler manner, wherein the regeneratively cooled nozzle extension resulting therefrom has to have a high cooling efficiency. Furthermore, exemplary embodiments of the present invention provide a regeneratively cooled nozzle extension that can be manufactured in a simple manner and has a high cooling efficiency.
The invention provides a method for manufacturing a regeneratively cooled nozzle extension of a rocket combustion chamber, the nozzle extension comprising a first and a second wall are arranged coaxially to each other and between which a number of cooling channels is configured, the cooling channels being laterally delimited by cooling channel webs. The first and the second wall are connected to each by a positive fit by cooling channel webs of the first wall engaging with corresponding recesses in the second wall for forming the positive fit. According to the invention, the positive fit is generated by a forming process in the region of the cooling channels of the second wall having the recesses.
The method according to the invention allows the simple manufacture of a regeneratively cooled nozzle extension because it can be manufactured substantially with mechanical processing steps. By principally avoiding the use of brazing and welding methods, the production-related expenditure for manufacturing the regeneratively cooled nozzle extension can be kept low, thereby also lowering the costs for manufacturing the nozzle extension.
Advantageously, the forming of the second wall is carried out from a side opposing the first wall. In this manner, producing the positive fit can take place in a simple and fast manner.
In order to be able to implement a fast and efficient manufacture of the nozzle extension, the forming can take place in the region of one cooling channel or in the region of a plurality of cooling channels at the same time. For manufacturing the complete nozzle extension, the positive fit is then generated in the region of one or a plurality of cooling channels in a plurality of sequentially staggered method steps.
According to one configuration variant, the force necessary for forming the second wall can be applied by one or by a plurality of rollers arranged side-by-side and/or one behind the other. By a plurality of rollers arranged side-by-side, the simultaneous forming of a plurality of cooling channels can be implemented, which accelerates manufacture. In principal, the forming can also be carried out with other suitable tools.
Alternatively or additionally, excess pressure and/or negative pressure can be used for forming the second wall. The forming can also be implemented, for example, by providing a negative pressure in the region of the cooling channels and a simultaneous excess pressure on the second wall.
It is further provided that prior to the forming step, the first and the second wall are positioned as a whole in axial direction one above the other in such a manner that at least some cooling channel web ends remote from the first wall project into the recesses. Then, for producing the positive fit, only the forming of the second wall having the recess is necessary in the region of the cooling channels. “As a whole” means that not only individual segments are positioned on top of each other but the first and second walls which are already parabolically shaped are arranged on top of each other.
In a first alternative, the forming takes place in the region between two directly adjacent cooling channel webs. In another alternative, the forming takes place in the region of one or a plurality of adjacent cooling channel webs in such a manner that the second wall is brought into abutment against the web end remote from the first wall of one or a plurality of cooling channel webs without producing a positive fit, wherein the positive fit between the first and the second wall takes place at least by the cooling channel webs adjacent to the cooling channel webs. This provides a simpler and faster manufacturing of the nozzle extension because a smaller number of forming steps for manufacturing the complete nozzle extension are necessary. Moreover, by this configuration variant, the shape of the cooling channels can be varied in a desired manner.
Advantageously, the forming takes place in such a manner that each nth cooling channel web is connected in a positively fitting manner to the second wall, wherein n is greater than 2. For example, the forming of the second wall can take place in such a manner that only every second or third cooling channel web is used for the formation of the positively fitting connection. This means, between the cooling channel webs provided for the forming process, additional, shorter cooling channel webs are introduced on the first wall, the height of which webs is determined in consideration of the necessary deformation and flow conditions.
For stiffening the regeneratively cooled nozzle extension it can further be provided that at least one stiffening ring with a predetermined axial length is brought into abutment against the second wall of the nozzle extension so that the stiffening ring lies in a plane that is orthogonal to a rotational axis of the nozzle extension. A respective stiffening ring increases the stiffness of the nozzle extension, in particular in the region of the geometry changed by forming. Depending on the configuration of the axial length of a respective stiffening ring (up to a monolithic outer skirt which can be comparable with the length of the nozzle extension or individual sections), the stiffness of the nozzle extension can be maximally influenced.
The at least one stiffening ring can have a projection in the region of the deformations, where the projection is adapted to the shape of the deformations, whereby the shape of the second wall in the region of the cooling channels is raised when the internal pressure (due to a cooling medium flowing through the cooling channels) is applied.
Furthermore, the invention provides a regeneratively cooled nozzle extension for a rocket combustion chamber, the nozzle extension comprising a first wall and a second wall that are arranged coaxially to each other and between which a number of cooling channels are configured that are laterally delimited by cooling channel webs. In case of the nozzle extension, the first and the second wall are connected to each other by a positive fit, wherein cooling channel webs of the first wall engage with corresponding recesses of the second wall for producing the positive fit. In the region of a respective positive fit, according to the invention, the second wall having recesses is shaped by forming in the region of the cooling channels.
The regeneratively cooled nozzle extension according to the invention can be manufactured in a simple and cost-effective manner, wherein a sufficient cooling efficiency is ensured due to the inventive connection method.
It is advantageously provided that the first and the second wall each have a rotationally symmetric, in particular, parabolic initial contour.
In a further advantageous configuration it is provided that each nth cooling channel web is connected to the second wall in a positively fitting manner, wherein n is greater than 2.
According to a further configuration, a stiffening ring with predetermined axial length is brought into abutment against the second wall of the nozzle extension so that the stiffening ring lies in a plane orthogonal to a rotational axis of the nozzle extension.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
The invention is described in more detail hereinafter by means of exemplary embodiments. In the figures:
As is shown more clearly in the enlarged details of
The cooling channel webs 5 differ from the cooling channel webs 10 in their radial length and in the configuration of their ends. While the cooling channel webs' 5 ends 12 facing away from the inner liner 1 are configured like a dovetail that widens from a constriction towards the end, the cooling channel webs' 10 ends 15 facing away from the inner liner 1 are shorter. Moreover, the ends 15 of the cooling channel webs 10 do not have a particular cross-sectional shape.
Corresponding to size and arrangement of the cooling channel webs 5 or their ends 12, the outer casing 2 has recesses 6. The recesses 6 extend along the course of the cooling channel webs 5 in the direction of the rotational axis 50. The recesses 6 of the outer casing 2 initially have a rectangular cross-section so that they receive the dovetail-shaped ends 12 of the cooling channel webs 5 when the inner liner 1 and the outer casing 2 are arranged on top of each other. The outermost ends of the dovetail-shaped ends 12 are adapted here to the width of the recesses 6. The total height of the cooling channel webs 10 (if present) is slightly smaller than a respective base 16 of the cooling channel 5 to which base the dovetail-shaped ends 12 are connected (cf.
In the
Producing the positive fit is carried out, for example, in a plurality of steps in a staggered manner over one or a plurality of adjacent cooling channels 11 at the same time, whereby a distortion of the inner contour can be prevented to the greatest possible extent. The force necessary for forming the outer casing 2 is applied by the roller or rollers 8. As a result, the outer casing 2 has a curvature (formed shape 13) directed towards the inner liner 1 in the region of respective formed cooling channels 11 which curvature is obtained by the forming process.
The exemplary embodiments in the
As a modification of the exemplary embodiments shown in the Figures, it is also possible that more than one of the shorter cooling channel webs 10 is arranged between in each case two cooling channels webs 5. Thus, for example, every third of the cooling channel webs 5, 10 could be used for producing a positive fit.
Due to the deformation of the outer casing 2 which—as the inner liner 1—has a parabolically shaped, rotationally symmetrical initial contour, the stiffness of the nozzle extension 100 increases.
To further increase the stiffness of the nozzle extension, the stiffening rings 3 already mentioned above in connection with
The stiffening rings 3 can also be provided with inner ribs 4 on the side facing the outer casing 2, whereby the shape of the outer casing 2 is raised in the region of the channels when internal pressure is applied. This is exemplary shown in
By the selective use of cooling channel webs for connecting the outer casing 2 to the inner liner 1 via cooling channel webs 5 provided for the positive fit, there is further the possibility to use nozzle extensions having a variable number of cooling channel webs.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102010007272.9-14 | Feb 2010 | DE | national |
