EP4088015A1

EP4088015A1 - Nozzle with variable outlet cross-section for rocket engine and rocket engine comprising such a nozzle

Info

Publication number: EP4088015A1
Application number: EP20845574.1A
Authority: EP
Inventors: Julien SENON
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-01-08
Filing date: 2020-12-30
Publication date: 2022-11-16
Also published as: FR3105994A1; WO2021140053A1

Abstract

The invention relates to a rocket engine nozzle (1) with a variable cross-section, the nozzle comprising: - a stationary part (2); and - a movable part (3), capable of moving between a retracted position, in which the movable part (3) surrounds the stationary part (2), and in which the stationary part (2) forms the inlet and the outlet of the nozzle (1), and a deployed position, in which the stationary part (2) forms the inlet of the nozzle and the movable part (3) forms the outlet of the nozzle (1); the movable part (3) being configured such that its outlet cross-section increases as the movable part (3) moves from the retracted position to the deployed position, and such that, when the movable part (3) forms the outlet of the nozzle (1), the seal between the stationary part (2) and movable part (3) where they join prevents any leakage of the gases discharged during the operation of the nozzle.

Description

Variable outlet section nozzle for rocket motor and rocket motor comprising such a nozzle

The invention relates to the field of rocket engines, and more particularly relates to a nozzle for a rocket engine intended to improve the efficiency of this engine.

The problem of rocket engine efficiency is a well-known problem in aerospace. Indeed, we note that for a rocket engine at fixed speed, the thrust produced varies significantly during flight, in particular depending on the altitude at which the rocket is traveling. Indeed, for the thrust of a rocket engine to be maximum, the static pressure of the ejected gases must be identical to the ambient pressure prevailing around the rocket. However, during use, the ambient pressure around the rocket varies depending on the altitude at which it is flying. In known manner, the static pressure of the ejected gases is determined by the ratio between the section of the throat of the nozzle and the outlet section of the nozzle. On a conventional rocket engine, this section ratio is fixed. Consequently, the static pressure of the ejected gases does not vary and therefore cannot be kept equal to the ambient pressure during the whole flight. When the pressure of the ejected gases is greater than the ambient pressure, the ejected gas flow must then expand in order to adapt to the ambient pressure. The ejected gas flow is then no longer parallel to the stroke of the rocket. The amount of movement produced is therefore reduced and generates a loss of engine efficiency. When the pressure of the ejected gases is lower than the ambient pressure, a suction phenomenon occurs, which slows the rocket. It also causes a loss of engine efficiency. In addition, when the pressure of the ejected gases is much lower than the ambient pressure, a phenomenon of separation of the ejected gases appears. This separation is often asymmetric, resulting in instabilities of thrust and lateral loads on the engine, which, in the most severe cases, can jeopardize the integrity of the engine.

A known solution for limiting the consequences of the problems described above consists in adapting the nozzle to a given altitude, the ambient pressure of which corresponds to the average of the pressures encountered by the rocket motor during its use. In such a case, the pressure of the ejected gases is: - lower than the ambient pressure during take-off and up to the adaptation altitude;

- equal to the ambient pressure at the adaptation altitude; and

- above ambient pressure at altitudes above the adaptation altitude.

The resulting loss of efficiency compared to the efficiency achieved at the adaptation altitude can reach 20 to 30% at the time of take-off, then nearly 10% for altitudes above the adaptation altitude. The loss of efficiency on take-off is undoubtedly the most problematic, because it is during this phase that the mass of the rocket is the greatest (due to the fact that its tanks contain a maximum quantity of propellants), and, moreover, the rocket is then subjected to a maximum drag due to the density of the air which is maximum.

In order to remedy the drawbacks mentioned above, solutions using a nozzle of variable section have been proposed, the modification of the section making it possible to have a nozzle that can be adapted during flight at different altitudes. Such solutions generally involve hinged flaps forming the end of the nozzle, and an actuating mechanism for changing the orientation of the flaps in order to tighten or widen the end of the nozzle. However, these solutions have the disadvantage of adding a large mass, and, above all, of modifying the profile of the nozzle too much. In general, no solution is known which is not penalizing in terms of costs and / or mass, and which makes it possible to modify the section of a nozzle continuously during use, so that the profile of the nozzle is kept very close to the ideal profile.

The object of the present invention is to remedy the drawbacks of the state of the art, and more particularly those set out above, by proposing a variable-section nozzle, the section of which can be modified during use while at the same time. moving as little as possible from the ideal profile.

To this end, the invention relates to a rocket engine nozzle with variable outlet section, the nozzle comprising:

- a fixed part; and

- a movable part, movable between a retracted position, in which the movable part surrounds the fixed part, and in which the fixed part forms the entrance and the outlet of the nozzle, and a deployed position, in which the fixed part forms the inlet of the nozzle and the movable part forms the outlet of the nozzle; the movable part being configured so that its outlet section increases when the movable part moves from the retracted position to the deployed position, and so that, when the movable part forms the outlet of the nozzle, the seal between the fixed part and the movable part at their junction makes it possible to prevent any leakage of the gases ejected during the operation of the nozzle.

Thus, by using a nozzle comprising a fixed part and a movable part, the section of which increases with its displacement from the retracted position to the deployed position, the invention makes it possible to vary the section of the nozzle, continuously, in order to adapt it to a wide range of altitudes. The invention makes it possible to adapt the nozzle over a wide range of altitudes while remaining as close as possible to the profile of the ideal profile of the nozzle, particularly from the point of view of the flow of fluids. The use of a nozzle in accordance with the invention thus makes it possible to avoid the loss of 20 to 30% of take-off thrust that is observed on a conventional nozzle. The invention therefore makes it possible to significantly increase the payload, while also reducing the cost, reduced to the mass, of sending the payload into orbit. The invention can also make it possible to limit the use of boosters, which are considered to be polluting and expensive.

In one embodiment, the movable part comprises a set of tiles, in which each tile is movable in translation relative to the fixed part of the nozzle, between a retracted position corresponding to the retracted position of the movable part, and a corresponding deployed position in the deployed position of the movable part, the set of tiles being configured so that, when the movable part forms the outlet of the nozzle, at least one section of the set of tiles forms a continuous envelope between the fixed part and the outlet of the nozzle, the tiles being contiguous two by two over the whole of this section, and so that an internal surface of the set of tiles has a circular section at the level of an outlet section of the part fixed.

In one embodiment, the set of tiles is formed by an alternation of tiles of two types:

- tiles of a first type, having an evolving cross section, of increasing section in the direction of gas ejection; - tiles of a second type, having an evolving cross section, of decreasing section in the direction of gas ejection.

In one embodiment, the internal surface of each tile is merged with a portion of a cylinder of revolution of diameter corresponding to the diameter of the internal surface of the set of tiles at the outlet section of the fixed part.

In one embodiment, the set of tiles has an equal number of tiles of the first type and tiles of the second type.

In one embodiment, the set of tiles comprises a total number of tiles greater than or equal to 4, and for example between 6 and 24.

In one embodiment, the nozzle comprises a system of rails for guiding the set of tiles.

In one embodiment, the rail system comprises at least one rail of a first type for guiding one or more tiles of the first type and at least one rail of a second type for guiding one or more. tiles of the second type.

In one embodiment, the rail system comprises one rail per tile.

In one embodiment, the nozzle comprises a drive system for moving the mobile part.

In one embodiment, the drive system comprises at least one actuator of a first type to ensure the driving of one or more tiles of the first type, and at least one actuator of a second type to ensure the driving of 'one or more tiles of the second type.

In one embodiment, the drive system comprises one cylinder per tile.

In one embodiment, each tile comprises, on each side, a connecting device cooperating with a corresponding connecting device of the adjacent tile to form a sliding connection.

The invention also relates to an engine comprising at least one nozzle conforming to that defined above.

The invention also relates to a rocket comprising at least one engine as defined above.

The present invention will be better understood on reading the following detailed description, given with reference to the accompanying drawings, in which:

- Figure 1 is a diagram showing the profile of a fixed part of a nozzle according to the invention; - Figure 2 is a side view of a nozzle according to the invention, a half-view showing the movable part of the nozzle in its retracted position, the other half-view showing the movable part in its deployed position;

- Figure 2a is a half-sectional view of the fixed and movable parts of the nozzle of Figure 2, the movable part being in the retracted position;

- Figure 2b is a half-sectional view of the fixed and movable parts of the nozzle of Figure 2, the movable part being in an intermediate position between the retracted and deployed positions;

- Figure 2c is a half-sectional view of the fixed and movable parts of the nozzle of Figure 2, the movable part being in the deployed position;

- Figure 2d is a sectional view of the fixed and movable parts of the nozzle in the configuration of Figure 2b, the section being seen in accordance with the sectional plane CC of Figure 2b;

- Figure 2e is a detail view of Figure 2d;

- Figure 3 is a side view of the nozzle of Figure 2, in its deployed position;

- Figure 4 is a front view of a tile of the first type of the movable part.

- Figure 5 is a side view of the tile of Figure 4;

- Figure 6 is a bottom view of the tile of Figure 4;

- Figure 7 is a perspective view of the tile of Figure 4;

- Figure 8 is a front view of a tile of the second type of the movable part;

- Figure 9 is a side view of the tile of Figure 8;

- Figure 10 is a bottom view of the tile of Figure 8;

- Figure 11 is a perspective view of the tile of Figure 8;

- Figure 12 is a top view of the fixed part of the nozzle, in a configuration with eight tiles;

FIG. 13 is a side view of the fixed part of the nozzle, in a configuration with eight tiles, the profile of the movable part in the retracted position being shown around the fixed part;

- Figure 14 is a detail view of a tile of the movable part of the nozzle;

- Figure 15 is a perspective view of the arrangement of two adjacent tiles; - Figure 16 is a view of a rocket equipped with a nozzle according to the invention.

The general architecture of a nozzle 1 according to the invention is described below with reference to Figures 1 to 3.

According to the invention, the nozzle 1 comprises a fixed part 2 and a movable part 3. As can be seen in FIG. 2, which consists of two half-views of the nozzle 1, the movable part 3 is movable relative to the part. fixed 2 between a retracted position, or retracted position, visible on the lower half of Figure 2 (and in Figure 2a), and a deployed position, or extended position, visible on the upper half of Figure 2 (and on the figure 2c). Between these two extreme positions, the mobile part 3 can take a plurality of intermediate positions, such as the position shown in FIG. 2b.

As shown in Figures 2 and 2a, the movable part 3 is located, in its retracted position, around the fixed part 2, and is positioned such that the free end of the movable part 3, which forms the section outlet 30 of the moving part, is located behind (relative to the direction of gas ejection shown in Figure 1 by the arrow FG) OR at the same level as the free end of the fixed part 2. In this position , the outlet section 10 of the nozzle 1, which constitutes the gas ejection orifice (i.e. the outlet of the nozzle), is formed by the outlet section 20 of the fixed part 2.

As shown in Figures 2 and 2c, the movable part 3 is located, in its deployed position, at least partially advanced with respect to the free end of the fixed part 2, and is positioned so that the outlet section 30 of the movable part 3 is located in the extension of the fixed part 2 and thus forms the outlet section 10 of the nozzle 1, and therefore the orifice for ejection of the gases from the nozzle.

Regardless of the position of the mobile part 3, the inlet section 12 of the nozzle 1 is formed by the inlet section 22 of the fixed part 2.

As shown in Figure 2b, the movable part 3 is located, in any intermediate position, between the retracted and deployed positions, partially advanced with respect to the free end of the fixed part 2, and is positioned so that the outlet section 30 of the movable part 3 is located in the extension of the fixed part 2 and thus forms the outlet section 10 of the nozzle 1, and therefore the gas ejection orifice of the nozzle.

Whatever the position of the mobile part 3, it is configured so that its section located at the level of the output section 20 of the fixed part 2 has a shape of circular section, of internal diameter equal to or greater than the external diameter of the fixed part 2 at the level of its outlet section 20. Advantageously, the internal diameter of the movable part 3 at the level of the outlet section 20 of the fixed part 2 is equal to the external diameter of the latter, or has a value very close to this external diameter, making it possible to ensure a seal between these two elements sufficient to prevent any leakage of the gases ejected during the operation of the nozzle. Thus, as shown in FIG. 2d, whatever the position of the movable part 3, the seal between the fixed 2 and movable 3 parts is ensured by contact between these two elements. In the example of the figures, the seal is ensured by a tight fit between the fixed 2 and mobile 3 parts at their junction. Alternatively, a sealing element can be provided interposed between the fixed part and the movable part, at their junction.

As shown in FIG. 1, the fixed part 2 has in the example a form of conventional nozzle, its internal surface being a surface of revolution of axis X. The fixed part 2 comprises, in the direction of the ejection of the gases : a convergent 24, a neck 26, and a divergent 28 whose free end forms the outlet section 20. The outlet section 20 of the fixed part 2 has a circular shape of radius A.

As shown in Figures 2 and 3, the mobile part is in the example produced by means of an assembly of elements, or tiles 32, 34, movable in translation. In the example, the set of tiles 32, 34 is formed by an alternation of elements 32, 34 of two types:

- tiles of a first type 32; and

- tiles of a second type 34.

Each tile 32, 34 has an evolving section. The section of the tiles of the first type 32 is increasing in the direction of the ejection of the gases, while the section of the tiles of the second type 34 is decreasing in the direction of the ejection of the gases. Thus, as visible in figure 2, the tiles are arranged so that the section of the tiles of the first type 32 the largest is on the side of the outlet section 30 of the movable part 3, the largest section of the tiles. of the second type 34 located on the opposite side. In the example of the figures, the shape of the tiles 32, 34 is such that the projection of the contour of their external surface on a diametral plane orthogonal to the median radial plane of each tile is triangular in shape. Thus, tiles 32, 34 have the general shape of a triangle, these triangles being arranged in opposite directions two by two.

The mobile part 3 has an equal number of tiles of each type, and in the example of Figures 1 to 11 and 14 to 15 comprises a total of twelve tiles, or six tiles 32, 34 of each type. Figures 12 and 13 show a fixed part intended for a set of tiles comprising eight tiles in total. The total number of tiles in the set of tiles will be at least equal to 4, and in particular between 6 and 24. It is possible, for example, to provide a set of tiles comprising for example 6, 8, 10 or 12 tiles.

As visible in Figures 2 and 2a, the tiles of the first type 32 and the tiles of the second type 34 are configured to form, in the retracted position of the movable part 3, an assembly surrounding the fixed part 2, and whose internal surface has a shape widening in the direction of gas ejection.

In the deployed position of the movable part 3, visible in particular in FIGS. 3 and 2c, the tiles 32, 34 form an assembly having, at the level of the outlet section 20 of the fixed part, a circular section, of which the diameter is equal to or greater than the external diameter of the fixed part 2 at the outlet section 20, and provided to prevent any escape of ejection gas between the two elements during operation of the nozzle.

The tiles 32, 34 of the set of tiles are arranged so that, when the movable part 3 is in a position in which it forms the outlet of the nozzle 1, at least one section 31 of the set of tiles, located between the outlet section 20 of the fixed part 2 and the outlet section 30 of the movable part, has a continuous internal surface, of circular section at the level of the outlet section 20 of the fixed part 2.

The passage from the retracted position to the deployed position, or to any intermediate position, of the mobile part 3 is obtained by sliding the tiles 32, 34, by means of a rail system 4. The rail system 4 comprises in example a plurality of rails 40, 42 including:

- rails of a first type 40, configured to cooperate with the tiles of the first type 32;

- rails of a second type 42, configured to cooperate with the tiles of the second type 34.

Preferably, the rail system 4 comprises as many rails of each type. In the example, the rail system 4 comprises one rail per tile 32, 34, and therefore comprises twelve rails in total, ie six rails of the first type 40 and six rails of the second type 42.

Each of the rails 40, 42 of the rail system 4 is, in the example of the figures, of rectilinear shape, and oriented in a direction parallel to the direction tangent to the profile of the divergent 28 at the level of the outlet section 20 of the part. fixed 2 (cf. figure 1, tangent line T).

In order to drive the movable part from one position to another, the nozzle 1 comprises a drive system 5 of the movable part 3, comprising in the example a plurality of jacks 50, 52 including:

- cylinders of a first type 50, configured to drive the tiles of the first type 32;

- jacks of a second type 52, configured to drive the tiles of the second type 34.

Preferably, the drive system 5 of the mobile part 3 comprises as many jacks 50, 52 of each type. In the example, the drive system 5 comprises one jack 50, 52 per tile 32, 34, and therefore comprises twelve jacks 50, 52 in total, i.e. six jacks of the first type 50 and six jacks of the second type 52 (some jacks not shown in Figure 3 for reasons of clarity).

An embodiment of the tiles 32, 34 included in the movable part 3 of the nozzle 1 is described below, in particular in relation to FIGS. 4 to 7 and FIGS. 8 to 11.

Figures 4 to 7 show different views of an exemplary embodiment of a tile of the first type 32.

Each tile of the first type 32 has a front end 320 and a rear end 322. The front end 320 of each tile of the first type 32 forms part of the outlet end of the movable part 3 in its retracted position. As shown in FIG. 6 which represents a cross section of a tile of the first type 32, the internal face 324 of each tile of the first type 32 coincides with a portion of a cylinder of revolution of radius identical to that of the outlet section. of the fixed part (radius A). Each tile of the first type 32 comprises on its outer face 326 a jack attachment 328, located for example approximately halfway along the tile. The actuator clip 328 makes it possible to fix the rod of the actuator 50 provided to drive the tile in motion. Furthermore, each tile of the first type 32 comprises, on its internal face 324, a device for connecting to the corresponding rail 40, such as a slide 330. We have shown a single slide 330, but several slides can be provided. The lateral edges of each tile of the first type 32 comprise a device for connecting to the adjacent tiles (which are therefore tiles of the second type 34), in the example in the form of a groove 332 shaped to cooperate with a tenon of form complementary present on each tile of the second type 34, which is described in more detail below.

Figures 8 to 11 show different views of an exemplary embodiment of a tile of the second type 34.

Each tile of the second type 34 has a front end 340 and a rear end 342. The front end 340 of each tile of the second type 34 forms part of the outlet end of the movable part 3 in its retracted position. As can be seen in FIG. 10 which represents a cross section of a tile of the second type 34, the internal face 344 of each tile of the second type 34 coincides with a portion of a cylinder of revolution, of radius identical to that of the cross section. exit of the fixed part (radius A). In addition, so that the different tiles 32, 34 can be contiguous when the movable part 3 is in the retracted position, each tile of the second type 34 has bevelled sides, oriented in a radial direction with respect to a circle of center C inscribed in the internal surface of the set of tiles 32, 34 at the rear end of the movable part 3 in the retracted position (i.e. the end opposite the outlet section 30 of the movable part 3). Each tile of the second type 34 has on its external face 346 a jack attachment 348, located in the example near the rear end 342. The jack attachment 348 makes it possible to fix the rod of the jack 52 provided to drive the cylinder. moving tile. Furthermore, each tile of the second type 34 comprises, on its internal face 344, a device for connecting to the corresponding rail 42, such as a slide 350. A single slide 350 has been shown per tile, but several slides can be provided. The lateral edges of each tile of the second type 34 comprise a device for connecting to the adjacent tiles (which are therefore tiles of the first type 32), in the example in the form of a tenon 352 shaped to cooperate with one of the tiles. grooves 332 of complementary shape present on each tile of the first type 32. The grooves 332 and the tenons 352 have complementary shapes making it possible to form a sliding connection, as can be seen in FIG. 15 and in FIG. 2e. In the example, each groove 332 has in section an enlarged part, of circular shape, and a narrowed part, and each tenon 352 has in section a complementary form. Any shape making it possible to produce a sliding connection, such as for example a dovetail shape, can alternatively be implemented.

The geometry and kinematics of the movable part 3 of the nozzle 1 are described below in relation with FIGS. 1 to 3.

As mentioned above, the movement of the tiles 32, 34 forming the movable part 3 is carried out in a direction parallel to the tangent to the profile of the fixed part 2 at its outlet section. FIG. 1 shows the tangent straight lines at points E and F. The orientation of the tangents T corresponds to the orientation of the rails 40, 42 of the rail system 4. The tangents T intersect at a point D, the triangle DEF being therefore isosceles. The configuration of the tiles 32, 34 of the movable part implies that the course of all the tiles 32, 34 of the same type is identical. Furthermore, the stroke of the tiles of the first type 32 between the retracted and deployed positions is less than that of the tiles of the second type 34. As shown in Figures 2, 2a, 2b, 2c and 3, the tiles of the second type 34 must cover a greater distance than the tiles of the first type 32 to move from one extreme position to another, and vice versa. In the example of the figures, to go from one extreme position to the other, the tiles of the second type 34 must travel a path twice as long as the tiles of the first type 32. This difference in travel implies a difference in length. rails 40, 42 for guiding the tiles 32, 34. In the example, the length of the rails 42 for guiding the tiles of the second type 34 is twice that of the rails 40 for guiding the tiles of the first type 32. Advantageously, the length of the rails of the second type 42 is at least equal to half of the side of the triangle DEF, ie the length of the segments GE and HF. Again advantageously, the length of the rails of the first type 40 is at least equal to a quarter of the side of the triangle DEF, ie half the length of the segments GE and HF. Such a configuration results in a difference between the radius A of the outlet section 20 of the fixed part 2 and the radius B of the circle inscribed in the internal surface of the set of tiles 32, 34 at the level of the outlet section 30. of the mobile part 3 (in the deployed position, see Figures 1 and 3) by 25%, which corresponds to an increase of approximately 56.25% in the area of the outlet section.

FIG. 16 represents a rocket 100 comprising an engine (not visible) equipped with a nozzle 1 in accordance with the invention. In the example, the system drive 5 of the movable part is fixed to a fixed element of the engine or of the structure of the rocket 100.

The invention described above makes it possible to adapt the nozzle over a wide range of altitudes, continuously, while remaining as close as possible to the ideal profile of the nozzle, particularly from the point of view of the flow of fluids. In particular, the invention avoids the loss of 20 to 30% of take-off thrust that is observed on a conventional nozzle. The invention therefore makes it possible to significantly increase the payload, while also reducing the cost, reduced to the mass, of sending the payload into orbit. The invention can also make it possible to limit the use of boosters, which are considered to be polluting and expensive.

Claims

1. Rocket engine nozzle (1) with variable outlet section, the nozzle comprising:

- a fixed part (2); and

- a movable part (3), movable between a retracted position, in which the movable part (3) surrounds the fixed part (2), and in which the fixed part (2) forms the inlet and the outlet of the nozzle ( 1), and a deployed position, in which the fixed part (2) forms the inlet of the nozzle and the movable part (3) forms the outlet of the nozzle (1); the movable part (3) being configured so that its outlet section (30) increases when the movable part (3) moves from the retracted position to the deployed position, and so that when the movable part (3) forms the outlet of the nozzle (1), the seal between the fixed part (2) and the moving part (3) at their junction makes it possible to prevent any leakage of the gases ejected during the operation of the nozzle.

2. Nozzle according to the preceding claim, wherein the movable part (3) comprises a set of tiles (32, 34) in which each tile (32, 34) is movable in translation relative to the fixed part of the nozzle (2 ), between a retracted position corresponding to the retracted position of the movable part (3), and an extended position corresponding to the deployed position of the movable part (3), the set of tiles being configured so that, when the movable part (3) forms the outlet of the nozzle (1), at least one section (31) of the set of tiles forms a continuous envelope between the fixed part (2) and the outlet of the nozzle (1), the tiles being contiguous two by two over the whole of this section (31), and so that an internal surface of the set of tiles has a circular section at the level of an outlet section of the fixed part (2).

3. Nozzle (1) according to the preceding claim, wherein the set of tiles (32, 34) is formed by an alternation of tiles of two types: tiles of a first type (32), having an evolving cross section. , of increasing section in the direction of gas ejection; tiles of a second type (34), having an evolving cross section, of decreasing section in the direction of gas ejection.

4. Nozzle according to claim 2 or 3, wherein the internal surface of each tile (32, 34) coincides with a cylinder portion of revolution of diameter corresponding to the diameter of the internal surface of the set of tiles at the level of the outlet section (20) of the fixed part (2).

5. Nozzle according to one of claims 3 and 4, wherein the set of tiles (32, 34) comprises an equal number of tiles of the first type (32) and tiles of the second type (34).

6. Nozzle according to the preceding claim, wherein the set of tiles (32, 34) comprises a total number of tiles greater than or equal to 4, and for example between 4 and 24.

7. Nozzle according to one of claims 2 to 6, comprising a rail system (4) for guiding the set of tiles (32, 34).

8. Nozzle according to the preceding claim, in combination with claim 3, wherein the rail system (4) comprises at least one rail of a first type (40) for guiding one or more tiles of the first type. (32) and at least one rail of a second type (42) for guiding one or more tiles of the second type (34).

9. Nozzle according to one of claims 7 and 8, wherein the rail system (4) comprises one rail (40, 42) per tile (32, 34).

10. Nozzle according to one of the preceding claims, comprising a drive system (5) for moving the movable part (3).

11. Nozzle according to the preceding claim, in combination with one of claims 2 to 9, wherein the drive system (5) comprises at least one cylinder of a first type (50) to ensure the drive of one or more tiles of the first type (32) and at least one actuator of a second type (52) for driving one or more tiles of the second type (34).

12. Nozzle according to the preceding claim, wherein the drive system (5) comprises one cylinder (50, 52) per tile (32, 34).

13. Nozzle according to one of claims 2 to 12, wherein each tile (32, 34) comprises, on each side, a connecting device (332, 352) cooperating with a connecting device (352, 332) corresponding to the adjacent tile to form a sliding link.

14. Engine comprising at least one nozzle (1) according to one of the preceding claims.

15. Rocket (100) comprising at least one engine according to the preceding claim.