A coupling shape which is advantageous for connecting the nozzle wall to
the airframe in a positionally accurate manner, together with sufficient allowance for expansion of the nozzle wall, results from the preferred embodiment of the invention according to Claims 2 to 5.
For nozzle walls which extend on both sides of the narrow part of a convergent/divergent thrust nozzle, an embodiment according to Claim 6 is particularly suitable, according to which the nozzle wall is angled in a V-shape and the securing elements are provided in wall areas on either side of the bend and the direction of the row is perpendicular to the axis of curvature. Owing to the arrangement of the securing elements in the flat areas of the wall on both sides of the bend, the nozzle wall is secured transversely to the narrow point or the axis of curvature without a separate securing system, using securing elements, being necessary.
In order to adapt the securing of the nozzle wall to the flow conditions in the nozzle in optimum manner, which conditions determine the thermal and mechanical loads on the nozzle wall, the thrust nozzle is advantageously formed according to Claims 7 and 8.
The structural complexity of the thrust nozzle is simplified by the embodiments of the invention according to Claims 9 to 11.
It is particularly advantageous for mounting and repair if the securing elements are screwed to the airframe.
6 Further advantageous embodiments of the invention with respect to design emerge from Claims 13 to 16.
The invention will be explained in further detail below with reference to the accompanying drawings which illustrate a preferred embodiment in which:
Figure 1 shows a perspective view partially in section of a Laval-thrust nozzle with a rectangular channel cross-section for jet engines; Figure 2a shows an outline of a flat, lateral nozzle wall; Figure 2b shows a perspective view of a nozzle wall bent in a V-shape; Figure 3a shows a cross-section according to Figure 1 of the flat nozzle wall which is screwed to the nozzle casing; Figure 3b shows a section according to Figure 1 of the thrust nozzle in the vicinity of the narrow cross-section with a wall bent in a V-shape in longitudinal section; 7 Figure 4a shows a cross-section of the thrust nozzle in the vicinity of a securing element according to Figure 3a; Figure 4b shows a cross-section of the thrust nozzle in the vicinity of a securing element according to Figure 3b; Figure 5a shows a schematic horizontal projection of the flat, lateral nozzle wall, in which the degrees of freedom of movement are indicated; and Figure 5b shows a schematic, perspective view of the nozzle wall which is bent in a V-shaped manner in which the degrees of freedom of movement are indicated.
Figure 1 is a Laval thrust nozzle 1, also called a convergently-divergently extending thrust nozzle, for a jet engine which is not shown in further detail. In order to connect the thrust nozzle 1 to a jet engine, the thrust nozzle can be provided with a flanged transfer pipe 2. In operation, gas flows axially through the thrust nozzle 1 in the flow direction S. Downstream, the thrust nozzle 1 opens into an expansion ramp 3 which increases the maximum thrust that can be achieved. The channel cross-section of the transfer pipe 2 merges into a 8 rectangular cross-section corresponding to the channel cross-section of the thrust nozzle 1. The nozzle casing 4 that is located between the transfer pipe 2 and the expansion ramp 3 in relation to the flow direction S acts as an airframe 41 which resists the gas pressure forces. In order to increase the rigidity of the nozzle casing 4 and in order to increase the cooling surface, the nozzle casing 4 is provided externally with a plurality of intersecting ribs 5. Towards the interior, ie. towards the flow channel K, the airframe 41 is substantially flat. The flow channel K, which is rectangular in crosssection, is delimited spatially by nozzle walls 6 coupled to the nozzle casing 4. In order to prevent overheating, cooling channels 7 pass through the nozzle walls 6 at their interior, adjacent the flow channel. The cooling channels 7 (see also Figures 2b, 3a, 4a and 5b) are, in the operative state, supplied with coolant by pipe lines which are not shown in further detail. Two nozzle walls 6a and 6b, which are opposite and parallel one another and are flat, delimit the flow channel K laterally, whilst an upper, offset nozzle wall 6c, which s bent in a V-shape, delimits the flow channel at the top. Two flat nozzle walls 6d and 6e, abutting one another in a V- shaped manner, delimit the flow channel K at the 9 bottom. The bends of the upper and lower nozzle wall areas delimited by the V-shape extend at a distance from and parallel to one another and are located at the same channel depth in relation to the throughflow and thus produce the flow channel K for the convergent-divergent transfer typical of a Laval nozzle. The upper and lower nozzle walls 6c, 6d and 6e are located with their lateral end edges 8 closely abutting the side walls 6a and 6b.
Figure 2a shows the side of the nozzle wall 6a that is on the righthand side in relation to the direction of flow S and remote from the flow channel K. For adaptation to the V-shaped path of the upper nozzle wall 6c, the righthand nozzle wall 6a includes a V-shaped recess 9. In addition, the claw-shaped construction and the grid-like arrangement of element accommodation means 10 on the airframe side can be seen on the nozzle wall 6a. An identical formation and similar arrangement of the element accommodating means 10 can be seen on the supporting structure side of the nozzle wall 6c in Figure 2b.
As can be seen in detail in Figures 3a and 3b and 4a and 4b, each nozzle wall 6a, b, c, d and e is coupled via a plurality of securing elements 11 to the adjacent airframe 4' in a pressure force transmitting manner. For this purpose, the path of the nozzle wall 6, extending parallel to the flat surface of the airframe 41 on the channel side, is spaced apart in parallel manner by the securing elements 11 located therebetween. In order to transfer the gas pressure forces absorbed by the nozzle wall 6 into the airframe 41, the securing elements 11 are, on the one hand, screwed to the airframe 41 and coupled to the nozzle wall 6 in a longitudinally displaceable and pressure force transmitting manner in each case in an element accommodating means 10. The securing elements 11 are mushroom-shaped in a securing plate 12. The securing elements 11 are disposed on the securing plate 12 in accordance with the position of the element accommodating means 10 on the nozzle wall 6. The securing elements 11 extend perpendicular to the securing plate 12 or the nozzle wall 6. on the nozzle wall side the securing elements 11 end in a head 13 formed as a sliding shoe, with steps 14 extending laterally, the steps 14 being surrounded by two retaining claws 15 of an element accommodating means 10 in each case for guiding a securing element 11 in a longitudinally displaceable manner. As can also be seen in Figures 2a and 2b, two retaining claws 15 are arranged at a distance from and parallel to one another, forming an element accommodating 11 means 10, and are, in each case, mounted on the airframe side on the nozzle wall 6. Each retaining claw 15 thus forms, together with the nozzle wall 6, a joint 16 which extends in the longitudinal direction, and the height of which transverse to the plane of the nozzle wall 6 is adapted to the height of the step 14 accommodated therein in a longitudinally displaceable manner, such that movements transversely to the plane of the nozzle wall 6 are substantially precluded.
As can be seen from Figures 2a and 2b, the element accommodating means 10 are arranged on the nozzle walls 6 at grid points 11, which result from two intersecting bands of imaginary parallel grid axes B. The grid angle a of the intersecting grid axes G is approximately 850. In order to show the gridlike arrangement of the element accommodating means 10 on the side of the nozzle wall 6 facing the airframe 41, the nozzle walls 6a and 6c are shown in Figure 2a or Figure 2b in the dismantled state, ie. without securing elements 11. For an even load distribution, the element accommodating means 10 are, with the exception of the element accommodating means 10 adjacent the recess 9. disposed in rows extending parallel to one another. The distance a between the rows is thus constant from row to row. The distance b between 12 the element accommodating means 10 in a common row is likewise constant. In the case of flat nozzle walls 6a, b, d, e (see Figure 2a) one element accommodating means 101 of one row is aligned, in each case, transversely to the row direction R, which extends approximately parallel to the direction of flow S, located on a common grid axis G' in contrast to the remaining element accommodating means 10 of the same row. By virtue of the joins 16 of the element accommodating means 101, which joins are aligned transversely to the direction R of the rows, ie. in the direction of the grid axis W, securing elements 111 which are coupled to the element accommodating means 107 are guided in a longitudinally displaceable manner transverse to the row direction R, which results in the nozzle wall 6 being secured at points relative to the supporting structure 41 in the row direction R.
The parallel lateral distance C2 between two retaining claws 151 of the element retaining means 101 oriented transversely is selected such that the securing elements 111 which are longitudinally displaceable therein are guided substantially without play at the sides.
13 In contrast to the flat nozzle walls 6a, b, d and e, the transversely directed element retaining means 101 for securing the nozzle wall 6c in the row direction R are unnecessary in the case of the angled nozzle wall 6c, since, owing to the Vshape of the nozzle wall 6c and the coupling to the supporting structure 41 via the securing elements 11, there results securing in the row direction in the vicinity of the bend as can be seen in Figure 3b. Unrestricted expansion of the nozzle wall 6c in the row direction R, extending from the bend, is, however, maintained owing to the longitudinally displaceable coupling.
In order to secure the nozzle wall relative to the structure 41 transversely to the row direction R, a number of securing elements 111 are guided in a longitudinally displaceable manner in an element retaining means 101 with minimal, or completely without, lateral play. The associated element retaining means 101 are disposed along a common grid axis G", which points in the direction R of the row, in the case of which the flat nozzle walls 6a, b, d and e are disposed near the edges and, in the case of the angled nozzle wall 6c, approximately in the centre; (see Figures 2b and 3a). Accordingly, the parallel lateral distance C2 between two retaining claws 1511 of these 14 element accommodating means 1011 are, as with the laterally directed element accommodating means 101, smaller than the lateral distance Cl in the case of the remaining element accommodating means 10, which are guided with lateral play. The degrees of freedom of movement resulting from the lateral play of the securing elements 11 relative to the element accommodating means 10 are indicated in Figures 3a and 4a, which show, in each case, a section transverse to the row direction R, shown by the arrows P2.
In Figures Sa and 5b, the arrows P1 and P2 indicate, in each case, the degrees of freedom for compensating the expansion in the flat nozzle wall 6a or the angled nozzle wall 6c which result from the above-described securing of the nozzle walls 6 owing to the alignment of the element accommodating means 10, 101 and 1011 transversely to or in the row direction R, and from the amount of the lateral play. The arrows P1 indicate an expansion possibility for the nozzle wall 6 owing to the longitudinal displaceability of the securing elements 11, whereas the arrows P2 show an expansion possibility owing to the lateral play of the securing elements 11 in the element accommodating means 10. This also applies to the is arrows P1 and P2 in the Figures 3a, 3b, 4a and 4b.
16 CLAIMS 1. Thrust nozzle for jet engines, with at least one nozzle wall on the hot gas side, which is connected via a plurality of securing elements distributed in the wall surface to an airframe, characterised in that the securing elements are disposed in a grid-like manner, in rows distanced from one another, between the airframe and the nozzle wall and are connected in a pressure force transmitting manner to the nozzle wall by an element accommodating means, wherein at least a majority of the securing elements are retained in the element accommodating means in a longitudinally displaceable manner in the row direction and with play in the transverse direction to the row, and the nozzle wall being secured in relation to the airframe at points against displacement transverse to and in the row direction.
2. Thrust nozzle according to Claim 1, characterised in that transverse to the row direction the nozzle is secured by a number of longitudinally displaceable securing elements, which elements are guided, substantially without play, transverse to the row direction.
17 3. Thrust nozzle according to Claim 1 or 2, characterised in that in the row direction the nozzle wall is secured by means of a number of securing elements that are longitudinally displaceable transverse to the row direction and which are retained substantially without play in the row direction.
4. Thrust nozzle according to Claim 3, characterised in that the securing elements which are longitudinally displaceable transverse to the direction to the row are located on a grid axis extending transverse to the row direction.
5. Thrust nozzle according to any one of the preceding claims, characterised in that the rows are parallel to one another.
6. Thrust nozzle according to Claim 1 or 2, characterised in that the nozzle wall is bent in a V-shaped manner and the securing elements are provided in wall areas either side of the bend curvature, and wherein the row direction is located perpendicular to the axis of the bend.
7. Thrust nozzle according to any one of preceding claims, characterised in that the row 18 direction is approximately in the flow direction of the thrust nozzle.
8. Thrust nozzle according to any one of the preceding claims, characterised in that in the direction of the row the nozzle wall is secured approximately in the vicinity of the nozzle throat.
9. Thrust nozzle according to any one of the preceding claims, characterised in that the rows are distanced evenly from one another.
10. Thrust nozzle according to any one of the preceding claims, characterised in that the securing elements are distanced equally from one another in the row direction.
11. Thrust nozzle according to any one of preceding claims, characterised in that the element accommodating means are mounted at the points of intersection of an imaginary regular grid, on the airframe side on the nozzle wall.
12. Thrust nozzle according to any one of the preceding claims, characterised in that the securing elements are screwed to the airframe.
I.
i 19 13. Thrust nozzle according to any one of the preceding claims, characterised in that the element accommodating means are each formed of two retaining claws disposed parallel to one another, which in use embrace in a sliding set a mushroomshaped head of a respective securing element.
14. Thrust nozzle according to any one of the preceding claims, characterised in that the element accommodating means are formed on the nozzle wall.
15. Thrust nozzle according to any one of the preceding claims, characterised in that the securing elements are formed of a securing plate connected to the airframe with securing elements projecting on the nozzle wall side for connection to the nozzle walls.
16. Thrust nozzle according to any one of the preceding claims, characterised in that the airframe forms the nozzle casing.