COMBUSTOR OF A LIQUID PROPELLENT MOTOR

Abstract

A combustor for a liquid propellent motor has an elongated hollow tubular casing having an inner wall delimiting a combustion chamber for the liquid propellent and an outlet nozzle for the combustion products, and an outer wall, both being coaxial to an axis of the casing; the inner and outer walls being spaced apart from each other in radial direction and delimiting at least one guiding conduit of a cooling fluid therebetween; a plurality of bar-shaped elements extending into the guiding conduit, which form a grid for perturbing the cooling fluid, stiffening the casing and increasing the heat exchange surface; the grid being part of a body made in one piece and of a single material along with the inner and outer walls.

Claims

1-13. (canceled)

14. A combustor of a liquid propellent motor, the combustor comprising: an elongated hollow tubular casing having an axis, the elongated hollow tubular casing including: an inner wall coaxial to the axis, the inner wall delimiting a combustion chamber for the liquid propellent and an outlet nozzle for the combustion products, the inner wall having a thickness of less than about 0.8 millimeters; and an outer wall coaxial to the axis; wherein the inner and outer walls are spaced from each other in a radial direction; the inner and outer walls delimiting at least one sealed guiding conduit for a cooling fluid therebetween in a feeding direction; turbulence generating means accommodated in the at least one sealed guiding conduit and intercepted by the cooling fluid; wherein the turbulence generating means include a plurality of bar-shaped elongated elements extending transversely to the radial direction, the turbulence generating means having end portions that are integrally connected to the inner wall and to the outer wall, thus forming part of a reinforcement of the inner wall; wherein the inner wall, the outer wall, and the plurality of bar-shaped elongated elements form parts of a substantially homogenous monolithic body, the substantially homogenous monolithic body has been made in one piece and of the same metal material by Additive Layer Manufacturing starting from powder of the metal material.

15. The combustor according to claim 14, wherein at least some of the plurality of bar-shaped elongated elements have at least one rectilinear bar stretch.

16. The combustor according to claim 15, wherein at least some of the rectilinear bar stretches are inclined with respect to one another and with respect to the axis.

17. The combustor according to claim 14, wherein at least some of the plurality of bar-shaped elongated elements have a cross-section that is circular, oblong, rectangular, or rhomboidal.

18. The combustor according to claim 14, wherein at least some of the plurality of bar-shaped elongated elements are tapered at least at one end thereof.

19. The combustor according to claim 14, wherein at least some of the plurality of bar-shaped elongated elements have a cross-section that is at least partly arched.

20. The combustor according to claim 14, wherein at least two of the plurality of bar-shaped elongated elements intersect each other in at least one node.

21. The combustor according to claim 14, wherein at least two of the plurality of bar-shaped elongated elements are tangent to each other at least one point.

22. The combustor according to claim 14, wherein at least some of the plurality of bar-shaped elongated elements intersect one another to form a first grid having a plurality of nodes.

23. The combustor according to claim 22, wherein the first grid is a substantially homogeneous grid along at least part of the at least one sealed guiding conduit.

24. The combustor according to claim 22, wherein at least some of the plurality of bar-shaped elongated elements intersect one another to form a second grid having a plurality of nodes and a different mesh from the first grid.

25. The combustor according to claim 14, further comprising: at least one plate-shaped radial baffle extending between the inner and outer walls and being integrally connected to the inner and outer walls to delimit two of the at least one sealed guiding conduit; wherein each of the two of the at least one sealed guiding conduit accommodating respective the turbulence generating means that are either equal or different; wherein the inner and outer walls, the baffles, and the turbulence generating means forming part of a body made in one piece and of a single metal material.

26. The combustor according to claim 14, wherein the single metal material has a mechanical strength that is higher than 400 MPa.

27. The combustor according to claim 14, wherein the single metal material has a thermal conductivity that is higher than 30 W/(m K).

28. A combustor of a liquid propellent motor, the combustor comprising: an elongated hollow tubular casing having an axis, the elongated hollow tubular casing including: an inner wall coaxial to the axis, the inner wall defining a combustion chamber for the liquid propellent and an outlet nozzle for the combustion products, the inner wall having a thickness of less than about 0.8 millimeters; and an outer wall coaxial to the axis; wherein the inner and outer walls are spaced from each other in a radial direction; the inner and outer walls defining at least one sealed guiding conduit for a cooling fluid therebetween in a feeding direction; a plurality of bar-shaped elongated elements disposed in the at least one sealed guiding conduit for interception by the cooling fluid, the plurality of bar-shaped elongated elements extending transversely to the radial direction, the plurality of bar-shaped elongated elements having end portions that are integrally connected to the inner wall and to the outer wall, thus forming part of a reinforcement of the inner wall; wherein the inner wall, the outer wall, and the plurality of bar-shaped elongated elements form parts of a substantially homogenous monolithic body, the substantially homogenous monolithic body has been made in one piece and of the same metal material by Additive Layer Manufacturing starting from powder of the metal material.

29. The combustor according to claim 28, wherein at least some of the plurality of bar-shaped elongated elements have at least one rectilinear bar stretch.

30. The combustor according to claim 28, wherein at least some of the plurality of bar-shaped elongated elements have a cross-section that is circular, oblong, rectangular, rhomboidal, or at least partly arched.

31. The combustor according to claim 28, wherein at least some of the plurality of bar-shaped elongated elements are tapered at least at one end thereof.

32. The combustor according to claim 28, wherein at least some of the plurality of bar-shaped elongated elements intersect one another to form a first grid having a plurality of nodes.

33. The combustor according to claim 32, wherein at least some of the plurality of bar-shaped elongated elements intersect one another to form a second grid having a plurality of nodes and a different mesh from the first grid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will now be described with reference to the accompanying drawings which show a non-limitative embodiment thereof, in which:

[0026] FIG. 1 diagrammatically shows in blocks and semi-radial section, with parts removed for clarity, a liquid propellent motor provided with a preferred embodiment of the combustor according to the dictates of the present invention;

[0027] FIG. 2 is a diagrammatic section taken along line II-II in FIG. 1;

[0028] FIG. 3 is diagrammatic, perspective partial view of a portion of a detail in FIGS. 1 and 2;

[0029] FIGS. 4 and 5 are a top view and a side view, respectively, of the detail in FIG. 3;

[0030] FIG. 6 shows a variant of a detail in FIGS. 1 and 2;

[0031] FIG. 7 shows a further variant of a detail in FIGS. 1 and 2 in section and on enlarged scale; and

[0032] FIGS. 8A and 8B are different sections on greatly enlarged scale taken according to line VIII-VIII in FIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

[0033] In FIG. 1, reference numeral 1 indicates, as a whole and with parts removed for clarity, a liquid propellent spacecraft motor.

[0034] Motor 1 comprises a thrust chamber 1A, comprising, in turn, an elongated combustor 2 having its own axis 3. Combustor 2 comprises a tubular metal casing 4. Casing 4 is shaped coaxially to axis 3 and, in the feeding direction of the combustion product indicated with arrow A in FIG. 1, comprises a tubular portion 6 with a cylindrical generating line and a shaped tubular portion 7, both coaxial to axis 3 and stably connected to each other in a fluid-tight manner (FIG. 1).

[0035] The tubular portion 6 laterally delimits a combustion chamber 8, in which a feeding conduit 9 of the liquid propellent and a feeding conduit 10 of the combustion supporting fluid, forming part of the thrust chamber 1A, lead.

[0036] Instead, the shaped tubular portion 7 delimits a converging-diverging nozzle 11, known per se, through which the combustion products generated in the combustion chamber 8 pass.

[0037] Again with reference to FIG. 1, casing 4 is a hollow casing and comprises an inner wall 12 defining the geometry of the combustion chamber 8 and of the nozzle 11, and an outer wall 13, both being coaxial to axis 3.

[0038] The walls 12 and 13 are blind walls impermeable to liquid or gaseous substances, are spaced apart from each other in radial direction, and delimit a sealed annular conduit 14 therebetween, which longitudinally extends between the inlet of the propellent/combustion supporting fluid in the combustion chamber 8 and the outlet of the combustion products from nozzle 11.

[0039] Conduit 14, which in the particular example described has a nearly constant thickness S along axis 3, forms part of a cooling circuit of combustor 2, indicated as a whole by reference numeral 16 in FIG. 1.

[0040] The cooling circuit 16 further comprises an inlet manifold 18 for introducing a cooling fluid into conduit 14, conveniently the same liquid propellent then sent to the combustion chamber 8 or another cooling fluid, and an outlet manifold 19 adapted to receive the cooling fluid from conduit 14. Between the two manifolds 18 and 19, conduit 14 guides the cooling fluid in a feeding direction indicated by reference numeral 20 in FIG. 1 and substantially parallel to a generating line of the inner wall 12.

[0041] In the particular example described, the cooling fluid moves in the direction opposite to the displacement of the combustion products. Alternatively, according to a different embodiment, the cooling fluid moves in a direction agreeing with the displacement of the combustion products.

[0042] Again with reference to FIG. 1, conduit 14 accommodates a plurality of bar-shaped elongated elements 22 which form part of casing 4 and extend between the walls 12 and 13. The elongated elements 22 are stably connected to the walls 12, 13 and are elongated in respective direction transverse to the feeding direction 20 of the cooling fluid in conduit 14.

[0043] The elongated elements 22 define a homogenous, narrow-mesh grid 23 for perturbing the cooling fluid which passes in direction 20 having the function of generating a predetermined turbulence in the cooling fluid itself in each zone of conduit 14.

[0044] In the particular example described, grid 23 has a plurality of nodes 25 for connecting together the bar-shaped elements 22. Conveniently, the nodes 25 are uniformly distributed inside conduit 14.

[0045] Alternatively, the distribution of the nodes 25 varies from one zone to the other of conduit 14 in order to make a different perturbation of the cooling fluid, and therefore a different removal of the heat through casing 4. The different distribution of the nodes 25 is obtained by varying the geometry, distribution or orientation of the elongated elements 22 in conduit 14.

[0046] Conveniently, the elongated members 22 have mutually consecutive rectilinear stretches 22A, each of which, in the particular example described, is defined by a piece of bar and leads to at least one node 25, as shown in FIGS. 3, 4 and 5 which depict a portion of grid 23.

[0047] In the particular example described, each rectilinear stretch 22A is butt-joined to a subsequent stretch 22A and is laterally delimited by an outer surface 26 having a rectilinear generating line parallel to a longitudinal extension axis 27 of the respective stretch 22A.

[0048] Each stretch 22A also has its own cross-section which is orthogonal to the respective longitudinal axis 27 being either circular or oblong in shape, either tapered or not at least at one of its ends, or having at least one curved portion, as shown in FIGS. 8A and 8B. In the latter case, each stretch 22A is shaped as a blade of a bladed stator crown of a traditional hydraulic machine. The sections of the various elongated stretches 22A are geometrically and dimensionally either equal or different from one zone to the other of conduit 14 or from one elongated element 22 to that adjacent thereto. Similarly, the lengths of the stretches 22A or of the elongated elements 22 are either equal or different from one zone to the other of conduit 14. According to a variant, at least some of the stretches 22A or of the elongated elements 22 are plate-shaped with rounded or non-rounded edges of the type shown in FIGS. 8a and 8b. Alternatively, the cross-section of the stretches 22A or of the elongated elements 22 may be either rectangular or rhomboidal. In the variant shown in FIG. 6, the elongated elements 22 comprise a single rectilinear stretch 22A which extends between the walls 12 and 13, in order to define a grid 30 which is simplified or has a larger mesh than that of grid 23. In such an embodiment, the elongated elements 22 extends again in directions forming an angle different from zero, in a mutual manner and with the feeding direction 20, and in positions which are transversely spaced apart, i.e. without contact points or so as to be arranged tangent to one another. Also in this case, the elongated elements 22 may have either a different distribution or geometrically or dimensionally different cross-sections as their position varies inside conduit 14, as described above.

[0049] According to a further variant, inside the conduit, narrow mesh grids 23 are present in some zones and large mesh grids 30 are present in other zones.

[0050] In the further variant shown in FIG. 7, the walls 12 and 13 are connected together by means of a plurality of plate-shaped radial baffles 31, which are also integrally connected to the walls 12 and 13 and extend along axis 3, not necessarily parallel to the axis 3 itself and along helical paths, for example. The radial baffles 34 divide conduit 14 into a plurality of smaller longitudinal conduits 32 placed side-by-side for guiding the cooling fluid. A perturbation grid of the fluid threads is provided within each smaller channel 32, which in this case is a narrow mesh grid 23. Alternatively, the smaller channels 32 accommodate a large mesh grid 30 or a combination of narrow and large mesh grids over at least one stretch. The channels 32 may have stretches free from grids interlayered or not with gridded stretches.

[0051] In general, the placement, geometry and size of each elongated stretch 22A or of an elongated element 22 is determined to obtain a given turbulence of the cooling fluid inside conduit 14 and a desired heat exchange surface, on one hand, and to confer shape stability to casing 4 regardless of the working temperatures and of the mechanical stresses to which the casing 14 itself is subjected, on the other.

[0052] Regardless of the type of grid used, the arrangement or section of the elongated elements 22 defining the grid itself, the walls 12 and 13 are again stably connected to the ends of the respective elongated elements 22, which thus behave as wedged beams on the walls 12 and 13 themselves. When the elongated elements 22 lead into a node, in addition to be wedged at their opposite ends, they also have intermediate portions wedged with respect to the other adjacent elongated elements 22.

[0053] Regardless of the distribution or geometry of the elongated elements 22, the walls 12 and 13 and the elongated elements 22 themselves are made of the same metal material, e.g. steel, in general nickel alloys or other equivalent metal materials, and the elongated elements 22 along with the walls 12 and 13 form part of a homogenous monolithic body made in one piece, preferably by means of the technique currently known as Additive Layer Manufacturing. If present, baffles 31 also form part of the body made in one piece as shown in FIG. 7.

[0054] Alternatively, one or both opposite ends of each elongated element 22 or of the baffles 31, when present, are stably connected to the respective wall 12, 13, e.g. by means of brazing.

[0055] In this case, different materials may be used to make one or both walls 12, 13 or elongated elements 22.

[0056] From the above, it is apparent that regardless of the process used to make the grid between the walls 12 and 13 and regardless of the type of grid or distribution of the grids along and inside conduit 14, or even regardless of the geometry or orientation of the elongation elements 22, each of the elongated elements 22 themselves triggers a localized turbulence and a predefined vorticity in the cooling fluid. Such a vorticity drastically reduces up to completely canceling out the thermal layering present in the conduits of the existing solutions, thus allowing the amount of removed heat to be increased, again as compared to the known solutions, with the cooling fluid features being equal.

[0057] More in detail, the elongated elements 22 force the cooling fluid to follow paths which are not parallel to wall 12, i.e. to the hot surface of casing 4, but are directed from the outer wall 13 or cold wall towards the inner wall 12. Thereby, a macroscopic mixing movement is created, which tends to uniform the temperature of the fluid along conduit 14 and in radial direction. By managing the orientation of the elongated elements 22 with respect to the feeding direction of the cooling fluid it is then possible to obtain a controlled detachment of the fluid vein on the elongated elements 22.

[0058] The presence of grids between the walls 12 and 13 then allows the operative loads to be distributed along main preferential force directions, and thus geometrically stable combustors to be obtained. In addition, as compared to the known solutions, the presence of structural grids inside conduit 14 allows the thickness of the inner wall to be reduced, and casings of lower weight and smaller dimensions to be provided in general. The above is substantially due to the construction of casing 4 which is a monolithic body made in one piece by using a single metal material.

[0059] Furthermore, the described grid solutions ensure greater freedom in defining the geometry of the combustion chamber.

[0060] Moreover, the presence of the grids 23, 30, with the volume of metal arranged between the walls 12 and 13 being equal, allows a considerable increase in heat exchange surface to be obtained. The speed of the cooling fluid can be modulated, and in general can be controlled, according to the density of the elongated elements 22 and to the size of the conduit 14 where the cooling fluid passes.

[0061] Finally, as compared to the known solutions described, the solution according to present invention provides the possibility to obtain a high effective combustion while avoiding the use of a permeable inner wall.

[0062] Again, with respect to the above-described known solutions, the inner wall 12 may have a very small thickness, and conveniently a thickness smaller than 0.8 millimeters.

[0063] The inner wall thickness may be brought to these low values because the elongated elements 22 define a structural reinforcement, either alone and along with the outer wall.

[0064] It is then apparent that the structural strength of casing 4 is much greater than that of the current known solutions, namely because the inner and outer walls and the inner grid defined by the elements 22 are manufactured in one monolithic piece made of a single material characterized by high mechanical strength.

[0065] The particular manufacturing method described then allows any type of grid to be implemented without any limitation, unlike the known solutions in which the process is always very constrained.

[0066] From the above, it is apparent that modifications and variants may be made to the described combustor 2 without departing from the scope of protection defined by the independent claim. In particular, it is apparent that the bar-shaped elongated elements 22 may be made by means of a different process and may have, for example, curved or plate-shaped stretches which inevitably lead to the formation of different grids from those indicated and shown in the accompanying figures.

[0067] Finally, conduit 14 may have stretches free from grids interlayered or not with gridded stretches which are equal to or different from one another.