Compact solid fuel propulsion system

Abstract

Compact Solid Fuel Propulsion System The invention relates to a propulsion system (1) capable of generating modular thrust, the propulsion system (1) comprising a body (10) enclosing a combustion chamber (8) in communication with at least one propulsion nozzle or valve (6) located outside the body (10), the body (10) further enclosing a solid fuel gas generator (9) configured to generate gases in the combustion chamber (8), wherein the gas generator (9) comprises a plurality of unit modules (5) independently ignitable by at least one combustion triggering device (40) and separated from each other by thermal insulation (30), the unit modules (5) being housed inside the body (10) and these unit modules (5) extending along the axis (A) and being distributed around said axis (A). Figure for the abstract: Fig. 2

Description

Title of the invention: Compact solid fuel propulsion system technical field

[0001] The present invention relates to the field of propulsion systems comprising a solid fuel gas generator. Previous technique

[0002] The use of solid fuel gas generators for engine propulsion systems is well known.

[0003] Such a solid fuel gas generator conventionally comprises a combustion triggering device and a solid fuel block. The combustion triggering device initiates the combustion of the solid fuel block, thereby generating a large quantity of gas. The generated gas is then channeled, directed, and ejected by means of nozzles or propulsion valves to propel the engine.

[0004] However, such propulsion systems lack flexibility in solid fuel management. Indeed, these propulsion systems are poorly suited when alternating between standby phases, low-speed combustion phases, and active phases.

[0005] To overcome these drawbacks, document EP 1 972 775 B1 proposes a propulsion device comprising several pyrotechnic charges that can be ignited independently of each other. In particular, document EP 1 972 775 B1 proposes arranging a plurality of pyrotechnic holding charges outside the body of the propulsion device. Each pyrotechnic holding charge is connected to an ignition means.

[0006] However, such a system is bulky and the ignition means are poorly protected. Description of the invention

[0007] The present invention aims to remedy the aforementioned drawbacks by proposing a compact propulsion system capable of delivering adjustable thrust.

[0008] To this end, the invention proposes a propulsion system capable of generating modular thrust, the propulsion system comprising a body extending along an axis which encloses a combustion chamber in communication with at least one nozzle or propulsion valve located outside the body, the body further enclosing a solid fuel gas generator configured to generate gases in the combustion chamber, the gas generator comprising at least one combustion triggering device, the gas generator comprising a plurality of unit modules independently ignitable by said at least one combustion triggering device and separated from each other by thermal insulation, the unit modules being housed in a support structure positioned inside the body and these unit modules extending along the axis by being distributed around said axis.

[0009] Thus, the presence of several independently ignitable unit modules allows the thrust generated by the gas generator to be modulated. The propulsion system can therefore be used in several different operating modes by varying the number of unit modules ignited over time. This makes it possible, in particular, to achieve several phases of high thrust separated in time by inactive phases or phases of lower thrust (so-called "multipulse" operation). Furthermore, such an architecture has the advantage of being particularly compact.

[0010] According to a particular aspect of the invention, each unit module comprises at least a first stage comprising at least one solid fuel block and a second stage adjacent to the first stage comprising a plurality of flammable pellets, the second stages of the unit modules being connected to the combustion triggering device(s).

[0011] The flammable pellets fulfill a relay charging function. They amplify the heat flux of the initiation chain to facilitate the ignition of the solid fuel block.

[0012] According to a particular aspect of the invention, the flammable pellets are present in a defined volume between a first grid and a second grid, the first grid being interposed between the flammable pellets and the combustion chamber and the second grid separating the first stage from the second stage of the unit modules.

[0013] The grids help to retain the flammable pellets and to limit the passage of unwanted particles or waste into the combustion chamber.

[0014] According to a particular aspect of the invention, each unit module is separated from the combustion chamber by an insulating flap configured to break when the unit module is in combustion.

[0015] Such an insulating cover limits the risk of unwanted ignition of a unit module due to the hot gas present in the combustion chamber. Its rupture then allows the gases generated by the unit module to escape.

[0016] According to a particular aspect of the invention, the gas generator comprises at least one passage channel extending along the axis between the unit modules, the passage channel being surrounded by the thermal insulation, the passage channel housing the combustion triggering device.

[0017] Such a configuration is particularly compact while allowing significant protection of the combustion triggering device.

[0018] According to a particular aspect of the invention, the gas generator further comprises an electrical system configured to power the combustion triggering device(s), the electrical system being located opposite the combustion chamber along the axis.

[0019] Thus, the electrical system is protected from hot gases, and the gas generator can be integrated as close as possible to the internal walls of the body.

[0020] According to a particular aspect of the invention, the propulsion system comprises a plurality of propulsion valves. The propulsion system may also comprise a plurality of nozzles.

[0021] Thus, the directional control of the craft enabled by the propulsion system is improved.

[0022] The invention also relates to a method of directional control of a machine comprising a propulsion system as described above, the method comprising the ejection of gases generated by the gas generator through the propulsion nozzle(s) or valve(s) oriented in a determined manner to obtain thrust in the desired direction.

[0023] According to a particular aspect of the invention, said method makes it possible to control the altitude of the craft.

[0024] According to a particular aspect of the invention, the method comprises a first push phase in which a first part of the unit modules is lit and a second push phase in which a second part of the unit modules different from the first part is lit, the second part of the unit modules being lit after the first part. Brief description of the drawings

[0025] [Fig-1] Fig. 1 is a schematic exploded perspective view of an example of propulsion system according to the invention.

[0026] [Fig.2] The [Fig.2] is a schematic cross-sectional view of the propulsion system of the [Fig.1].

[0027] [Fig.3] The [Fig.3] is a graph illustrating the thrust generated during the ignition of all solid fuel blocks.

[0028] [Fig.4] The [Fig.4] is a graphic illustrating the thrust generated when the solid fuel blocks are ignited in series.

[0029] [Fig.5] The [Fig.5] is a graphic illustrating the thrust generated when the solid fuel blocks are ignited in series with inactive phases. Description of the implementation methods

[0030] Figures 1 and 2 illustrate an example of propulsion system 1. Propulsion system 1 is capable of generating modular thrust.

[0031] The propulsion system 1 comprises a body 10. The body 10 extends axially along an axial direction DA. The body 10 extends radially along a radial direction DR. The body 10 may have a circular cross-section or an elliptical cross-section. The body 10 extends about an axis A. The axis A defines the axial direction DA. The axis A is preferably located at the center of the body 10. The axis A may correspond to a common line between several planes of symmetry of the body 10. The body 10 may have a shape of revolution about the axis A. The body 10 may have a dome shape.

[0032] The propulsion system 1 comprises at least one propulsion nozzle or valve 6. Preferably, to improve directional control of the propulsion system, it comprises a plurality of propulsion valves 6 or a plurality of nozzles. The nozzle(s) or propulsion valve(s) 6 are preferably steerable. In the example illustrated in Figures 1 and 2, the propulsion system 1 comprises six propulsion valves 6. The nozzle(s) or propulsion valve(s) 6 are located outside the body 10. The nozzle(s) or propulsion valve(s) 6 may extend from one of the axial ends of the body 10, as illustrated in Figures 1 and 2. The opening area of ​​the nozzle(s) or propulsion valve(s) 6 is controllable. The nozzle(s) or propulsion valve(s) 6 may be controlled in an "on / off" mode, in which the nozzle(s) or propulsion valve 6 is either fully open or fully closed.The propulsion nozzles or valves 6 can also be controlled proportionally, in which the opening of the propulsion nozzle or valve 6 varies. In particular, in proportional mode, the propulsion nozzle or valve 6 can have one or more intermediate opening positions between the fully open and fully closed positions. The propulsion nozzles or valves 6 can be controlled by an electropneumatic device. The propulsion nozzles or valves 6 can also be controlled by a hydraulic device. The propulsion nozzles or valves 6 can be configured to allow the propulsion system 1 to move along three perpendicular axes.

[0033] The body 10 contains a combustion chamber 8. The nozzle(s) or propulsion valve(s) 6 are in communication with the combustion chamber 8. The body 10 may contain a single combustion chamber 8.

[0034] The body 10 further contains a solid fuel gas generator 9. The gas generator 9 is configured to generate gases in the combustion chamber 8. The gas generator 9 is adjacent to the combustion chamber 8 and offset from it along the axial direction DA or along the axis A. The gas generator 9 can extend along the radial direction DR over substantially the entire cross-section of the body 10. Thus, the gas generator 9 can be in contact with the internal walls of the body 10. The gas generator 9 can be located on the side of a second axial end of the Body 10, which is opposite the first axial bottom on which the nozzles or valves 6 are located. The gas generator 9 can be situated on the side of the second axial bottom which defines a base of the dome.

[0035] The propulsion system 1 may include a spacer 80 configured to axially fix the gas generator 9 in the body 10. The spacer 80 allows the axial positioning of the gas generator 9 in the body 10 to be adapted according to the length of the solid fuel blocks 20 used. Indeed, the length of the solid fuel blocks 20 used depends on the mission that the vehicle equipped with the propulsion system 1 will perform. The spacer 80 extends radially over the entire cross-section of the body 10. The spacer 80 may be in the form of a disc, a cylinder, or a truncated cone. The gas generator 9 may be located between the spacer 80 and the combustion chamber 8. The spacer 80 may be located on the side of the second axial end.

[0036] The gas generator 9 comprises a plurality of unit modules 5. The unit modules 5 may have an elongated shape extending along the axial direction Da. The unit modules 5 are distributed around the axis A. The unit modules 5 may be offset from the axis A with respect to the radial direction DR (not located on the axis A) and are situated around it. The gas generator 9 may comprise at least four, for example at least eight, unit modules 5 housed within the body 10. The number of unit modules 5 depends on the mission to be performed by the craft equipped with the propulsion system and on the dimensions of said craft.

[0037] The unit modules 5 extend along the axial direction DA between a front face 5a and a rear face 5b. The front face 5a and the rear face 5b of the unit modules 5 may be perpendicular to the axis A. The front face 5a and the rear face 5b of the unit modules 5 are connected by one or more lateral faces 5c. The front face 5a of the unit modules 5 faces the combustion chamber 8. The rear face 5b of the unit modules 5 may be in contact with the wedge 80. The unit modules 5 may have a cylindrical shape of revolution, as illustrated in Figures 1 and 2. The unit modules 5 are then in the form of bars. Such a cylindrical shape of revolution is preferred to ensure a constant and controlled gas flow for a given pressure. Such a cylindrical shape of revolution also facilitates manufacturing. The unit modules 5 may also have a frustoconical shape.The invention remains within the scope of the invention even if the unit modules 5 have other shapes. The unit modules 5 are offset along the radial direction DR. A single plane transverse to the axis A intersects several unit modules 5.

[0038] Preferably, to simplify the design, all the unit modules 5 are identical. However, the unit modules 5 may have different shapes and / or different dimensions, for example to adapt to geometric constraints for the layout in propulsion system 1 and / or to adapt to the desired thrust profile.

[0039] The unit modules 5 are separated from each other by a thermal insulator 30. Thus, the lateral faces 5c of the unit modules 5 can be covered by the thermal insulator 30. The thermal insulator 30 may be a pourable varnish. The thermal insulator 30 may comprise polyurethane.

[0040] The unit modules 5 are housed in a retaining structure. The retaining structure holds the unit modules 5 in a predetermined position. The retaining structure is located within the body 10. The retaining structure may be in contact with the internal walls of the body 10. The retaining structure acts as reinforcement. The retaining structure defines a plurality of cavities that accommodate the unit modules 5. Thus, the unit modules 5 are positioned in the cavities of the retaining structure. Preferably, each cavity accommodates a single unit module 5. A space may be defined between the internal walls of the cavities of the retaining structure and the unit modules 5, this space being filled by thermal insulation 30. Thermal insulation 30 may also be present between the cavities of the retaining structure. The retaining structure may be made of metal.The support structure can also be made of an insulating material. Thermal insulation 30 can form the support structure.

[0041] Each unit module 5 comprises at least one solid fuel block 20. Each unit module 5 may comprise a single solid fuel block 20, as illustrated in Figures 1 and 2. The solid fuel block may conventionally comprise propellant.

[0042] The solid fuel blocks 20 extend along the axial direction DA between a front face 20a and a rear face 20b. The front face 20a and the rear face 20b of the solid fuel blocks 20 may be perpendicular to the axis A. The front face 20a and the rear face 20b of the solid fuel blocks 20 are connected by one or more lateral faces 20c. The solid fuel blocks 20 are configured to be ignited from their front face 20a. The solid fuel blocks 20 may have a cylindrical shape of revolution, as illustrated in Figures 1 and 2. The solid fuel blocks 20 are then in the form of bars. Such a cylindrical shape of revolution is preferred to ensure a constant and controlled gas flow for a given pressure. Such a cylindrical shape of revolution also facilitates manufacturing. The solid fuel blocks 20 may also have a frustoconical shape.The invention remains within its scope even if the solid fuel blocks 20 have other shapes. The solid fuel blocks 20 are offset along the radial direction DR. They are in the same plane. transverse to axis A intersects several solid fuel blocks 20. The entirety of the unit modules 5, or of the solid fuel blocks 20, can be located inside the body 10.

[0043] Preferably, to simplify the design, all the solid fuel blocks 20 are identical. However, the solid fuel blocks 20 may have different shapes and / or dimensions, for example to adapt to geometric constraints for the arrangement in the propulsion system 1 and / or to adapt to the desired thrust profile.

[0044] The rear face 20b of the solid fuel blocks 20 can form the rear face 5b of the unit modules 5. The side faces 20c of the solid fuel blocks 20 can define, at least in part, the side faces 5c of the unit modules 5. Thus, the side faces 20c of the solid fuel blocks 20 can be covered by the thermal insulation 30. The solid fuel blocks 20 are separated from each other by the thermal insulation 30. The side faces 20c of the solid fuel blocks 20 can be in direct contact with the thermal insulation 30.

[0045] The gas generator 9 further comprises one or more combustion triggering devices 40. The combustion triggering device(s) 40 are configured to ignite the unit modules 5. The combustion triggering device(s) 40 may be configured to ignite the unit modules 5 by means of an electrical signal. The combustion triggering device(s) 40 may comprise a plurality of branches. Each branch is configured to ignite a single unit module 5. Each unit module 5 is connected to a combustion triggering device 40. In particular, each unit module 5 is connected to a branch of a combustion triggering device 40.

[0046] For example, the combustion triggering device 40 shown in [Fig. 2] comprises six branches, each branch serving a unit module 5 adjacent to the illustrated combustion triggering device 40. In the example shown in [Fig. 2], the two unit modules 5 closest to axis A are served by the illustrated combustion triggering device 40, and the two unit modules 5 furthest from axis A can each be served by a combustion triggering device 40 not present in the cross-sectional plane shown in [Fig. 2]. According to one embodiment, all the unit modules 5 can be served by the same combustion triggering device 40.

[0047] The gas generator 9 includes at least one passage channel 90 configured to accommodate a combustion triggering device 40. The passage channel(s) 90 extend along the axial direction DA. The passage channel(s) 90 extend between the unit modules 5. The passage channel(s) 90 are insulated. thermally insulated from the combustion chamber 8. The passage channel(s) 90 are separated from the solid fuel blocks 20 by the thermal insulation 30. Thus, the passage channel(s) 90 are thermally insulated by the thermal insulation 30. Thus, the passage channel 90 is away from the walls of the body 10 and can serve several unit modules 5. Each passage channel 90 preferably serves at least two unit modules 5. The passage channel 90 illustrated in [Fig.2] serves, for example, six unit modules 5. The passage channel(s) 90 are made in the support structure.

[0048] The passage channel(s) 90 are preferably distributed so as to serve all the unit modules 5 while limiting the number of passage channels 90 required. Preferably, at least one passage channel 90 extends along axis A. At least one passage channel 90 may be located on axis A. Thus, the passage channel 90 is located in the center of the body 10 and is therefore capable of serving a very large number of unit modules 5. This configuration is particularly suitable when a single combustion triggering device 40 serves all the unit modules 5.

[0049] The gas generator 9 further comprises an electrical system (not shown) configured to power the combustion triggering device(s) 40, which is located at the rear of the gas generator 9 along the axial direction DA. Thus, the electrical system is separated from the combustion chamber 8 by the unit modules 5 and by the thermal insulation 30.

[0050] Thus, the combustion triggering device(s) 40 and the corresponding electrical system are properly protected while allowing a compact configuration of the gas generator 9.

[0051] Each unit module 5 may include an insulating cover 70. The insulating cover 7 separates the unit module 5 from the combustion chamber 8. The insulating covers 70 are configured to rupture when the associated unit module 5 is in combustion. The insulating covers 70 form the front face 5a of the unit modules 5. The insulating covers 70 may advantageously be made of silicone elastomer.

[0052] According to a particular embodiment, the unit modules 5 may comprise a first stage and a second stage. The first and second stages of the unit modules 5 are superimposed along the axial direction DA. The first stage comprises the solid fuel block(s) 20. The second stage may comprise a plurality of flammable pellets 50. The flammable pellets 50 perform a relay load function. The combustion triggering device(s) 40 are connected to the second stage of the unit modules 5, as illustrated in [Fig. 2]. Thus, the flammable pellets 50 are configured to ignite the solid fuel blocks 20 when the latter ignite.

[0053] The flammable pellets 50 comprise a pyrotechnic composition, for example one or more compressed aluminum and potassium perchlorate powders.

[0054] The second stage of the unit modules 5 is interposed between the combustion chamber 8 and the first stage of the unit modules 5 along the axial direction DA.

[0055] To hold the flammable pellets 50 in place, they can be held in a cage. The cage can be formed by a first grid 61 and a second grid 62. The flammable pellets 50 are located between the first grid 61 and the second grid 62. The first grid 61 and the second grid 62 extend between the lateral face(s) 5c of the unit module 5. The first grid 61 is interposed between the flammable pellets 50 and the combustion chamber 8. The first grid 61 may be in contact with the insulating cover 70 if one is present. The second grid 62 is interposed between the flammable pellets 50 and the solid fuel block 20. In particular, the second grid 62 may be in contact with the front face 20a of the solid fuel block 20.

[0056] The first grid 61 and the second grid 62 are made of metal.

[0057] The propulsion system as described above is configured to propel A vehicle. The vehicle could, for example, be an endo-atmospheric or exo-atmospheric glider, such as a hypersonic glider. The vehicle could also be a missile or an interceptor. The vehicle could also be a launcher.

[0058] The propulsion system as described above can be configured to provide directional control or trajectory control of the craft comprising said propulsion system. Thus, the invention also relates to a method for directional control of a craft comprising the propulsion system as described above. Such a method includes the ejection of gases generated by the gas generator 9 through propulsion nozzles or valves 6 oriented in a specific manner to obtain thrust in the desired direction. In particular, the propulsion system as described above can be configured to provide altitude control of the craft comprising said propulsion system.

[0059] Generally, the propulsion system as described above may have at least a first thrust phase and a second thrust phase. A first subset of the unit modules 5 is ignited during the first thrust phase. A second subset of the unit modules 5, different from the first subset, is ignited during the second thrust phase. A thrust phase is characterized by the number of unit modules 5 that are ignited. A thrust phase may involve the ignition of a single unit module 5. Conversely, a thrust phase may involve the simultaneous ignition of several unit modules 5.

[0060] In particular, the propulsion system as described above can have several modes of use. The modes of use can include one or more different thrust phases.

[0061] The propulsion system as described above may have, in particular, a first mode of operation illustrated in [Fig. 3]. In this first mode of operation, all of the unit modules 5 are ignited to generate a very powerful thrust. Thus, the first mode of operation comprises a single thrust phase.

[0062] The propulsion system as described above can also have a second operating mode illustrated in [Fig. 4]. In this second operating mode, the unit modules 5 are ignited one after the other so as to continuously generate thrust. The ignition of the unit modules 5 can be carried out at regular intervals, as illustrated in [Fig. 4], or at irregular intervals. Such a mode makes it possible to extend the operating time of the propulsion system. Thus, the second operating mode comprises a plurality of thrust phases.

[0063] The propulsion system as described above can also have a third operating mode illustrated in [Fig. 5]. In this third operating mode, the unit modules 5 are ignited one after the other, with the next unit module 5 being ignited only after the preceding unit module 5 has been extinguished. The ignition of the unit modules 5 can be carried out at regular or irregular intervals, as illustrated in [Fig. 5]. Such a mode makes it possible to extend the operating time of the propulsion system. Such a mode also allows for inactive phases during which no unit module 5 is ignited. Thus, the third operating mode comprises a plurality of thrust phases.

Claims

Demands

1. A propulsion system (1) capable of generating modular thrust, the propulsion system (1) comprising a body (10) extending along an axis (A) which contains a combustion chamber (8) in communication with at least one nozzle or propulsion valve (6) located outside the body (10), the body (10) further containing a solid fuel gas generator (9) configured to generate gases in the combustion chamber (8), the gas generator (9) comprising at least one combustion triggering device (40), the gas generator (9) comprising a plurality of unit modules (5) independently ignitable by said at least one combustion triggering device (40) and separated from each other by thermal insulation (30), the unit modules (5) being housed in a support structure positioned inside the body (10) and these unit modules (5) extending along the axis (A) and being distributed around said axis (A).

2. Propulsion system (1) according to claim 1, wherein each unit module (5) comprises at least one first stage comprising at least one solid fuel block (20) and a second stage adjacent to the first stage comprising a plurality of flammable pellets (50), the second stages of the unit modules (5) being connected to the combustion triggering device(s) (40).

3. Propulsion system (1) according to claim 2, in which the flammable pellets (50) are present in a defined volume between a first grid (61) and a second grid (62), the first grid (61) being interposed between the flammable pellets (50) and the combustion chamber (8) and the second grid (62) separating the first stage from the second stage of the unitary modules (5).

4. Propulsion system (1) according to any one of claims 1 to 3, wherein each unit module (5) is separated from the combustion chamber (8) by an insulating cover (70) configured to rupture when the unit module (5) is in combustion.

5. Propulsion system (1) according to any one of claims 1 to 4, wherein the gas generator (9) comprises at least one passage channel (90) extending along the axis (A) between the modules unit (5), the passage channel (90) being surrounded by the thermal insulation (30), the passage channel (90) housing the combustion triggering device (40).

6. Propulsion system (1) according to any one of claims 1 to 5, wherein the gas generator (9) further comprises an electrical system configured to power the combustion triggering device(s) (40), the electrical system being located opposite the combustion chamber (8) along axis (A).

7. Propulsion system (1) according to any one of claims 1 to 6, the propulsion system (1) comprising a plurality of propulsion nozzles or valves (6).

8. Method of directional control of a machine comprising a propulsion system (1) according to any one of claims 1 to 7, the method comprising the ejection of gases generated by the gas generator (9) through the propulsion nozzle(s) or valve(s) (6) oriented in a determined manner to obtain thrust in the desired direction.

9. Directional control method according to claim 8, said method enabling control of the altitude of the craft.

10. Directional control method according to claim 8 or 9, wherein the method comprises a first push phase in which a first part of the unit modules (5) is lit and a second push phase in which a second part of the unit modules (5) different from the first part is lit, the second part of the unit modules being lit after the first part.