SPACE PROPULSION SYSTEM

Abstract

A space propulsion system can serve miniaturised satellites, but can be scaled easily, and includes: a combustion chamber implemented by a cylindrical container having cylindrical walls, a first end provided with at least an injection duct for a combustion agent, a fuel and/or a mixture thereof, for the injection according to a direction tangential to the cylindrical walls so as to induce a helical combustion path in the combustion chamber, a possible additional perpendicular injection duct for a fuel or a combustion agent, and an opposite end provided with a discharge duct arranged according to a direction tangential to the cylindrical walls so as to receive and direct the helical path, wherein the cylindrical walls in case have a deposition of catalytic material inside thereof, for accelerating the combustion reaction; and a supersonic nozzle, connected to the discharge duct for discharging the combustion products in the combustion chamber.

Claims

1-12. (canceled)

13. A space propulsion system (1), comprising: a combustion chamber (10) implemented by a cylindrical container (11) having cylindrical walls (13), a first end (12) provided at least with an injection duct (15) for a combustion agent, a fuel and/or a mixture thereof, for the injection according to a direction tangential to said cylindrical walls so as to induce a helical combustion path in the combustion chamber (10), a possible additional injection duct (16) for a fuel or a combustion agent in direction perpendicular to said cylindrical walls, and an opposite end (14) provided with a discharge duct (19) arranged according to a direction tangential to said cylindrical walls (13) so as to receive and direct said helical path; and a supersonic nozzle (20), connected to said discharge duct (19) for discharging the combustion products in the combustion chamber.

14. The space propulsion system (1) according to claim 13, wherein the cylindrical walls have a deposition of catalytic material inside thereof, for accelerating the combustion reaction.

15. The space propulsion system (1) according to claim 13, comprising an electrolytic system (2), fed by an electric source (6), for the division of water into oxygen and hydrogen and for their injection in the tangential injection duct and in the additional injection duct, respectively.

16. The space propulsion system (1) according to claim 13, comprising a water tank (30) thereto an electrolytic system (2) is associated, fed by an electric source (6), for the division of water into oxygen and hydrogen and for their injection in the tangential injection duct and in the additional injection duct, respectively.

17. The space propulsion system (1) according to claim 13, comprising a water tank (30) having an electrolytic system (2) inside thereof, fed by an electric source (6), for the division of water into oxygen and hydrogen and for their injection in a mixture in the tangential injection duct.

18. The space propulsion system (1) according to claim 15, wherein the electrolytic system (2) feeds respective oxygen tank (7) and hydrogen tank (8), connected to the combustion chamber by suitable valves (17, 18).

19. The space propulsion system (1) according to claim 18, wherein the electrolytic system (2) has two branches respectively with an anode (4) and a cathode (5), for bubbling gaseous oxygen and hydrogen separately.

20. The space propulsion system (1) according to claim 13, wherein said electric source comprises a battery (6).

21. The space propulsion system (1) according to claim 13, wherein the combustion chamber (10) comprises a cylindrical container (11) having a first flat end (12) thereat there are two injection ducts (15, 16) a first duct thereof is tangential and parallel to said first end (12).

22. The space propulsion system (1) according to claim 21, wherein a second injection duct (16) is perpendicular to the cylindrical walls (13) of the combustion chamber (10), parallel to the plane of the first end (12), the position of the second injection duct (16) being such that the inlet in the combustion chamber (10) takes place near the inlet of the first duct (15), so that the gaseous flow injected through the first duct (15) intersects the gaseous flow injected through the second duct (16).

23. The space propulsion system (1) according to claim 13, comprising means for the ignition of said combustion agent, fuel and/or mixture thereof, comprising a deposition of catalytic material.

24. The space propulsion system (1) according to claim 13, comprising means for the ignition of said combustion agent, fuel and/or mixture thereof, comprising means for flashing an ignition spark.

25. The space propulsion system (1) according to claim 14, wherein said deposition of catalytic material comprises mainly Platinum.

26. The space propulsion system (1) according to claim 13, wherein the combustion chamber (10) is implemented as one single piece, and the combustion chamber has only the openings necessary to the injection and discharge.

27. The space propulsion system (1) according to claim 16, wherein the electrolytic system (2) feeds respective oxygen tank (7) and hydrogen tank (8), connected to the combustion chamber by suitable valves (17, 18).

28. The space propulsion system (1) according to claim 14, wherein said electric source comprises a battery (6).

29. The space propulsion system (1) according to claim 15, wherein said electric source comprises a battery (6).

30. The space propulsion system (1) according to claim 16, wherein said electric source comprises a battery (6).

31. The space propulsion system (1) according to claim 17, wherein said electric source comprises a battery (6).

32. The space propulsion system (1) according to claim 18, wherein said electric source comprises a battery (6).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be described hereinafter according to some preferred embodiment examples, provided by way of example and not for limitative purposes with reference to the enclosed drawings wherein:

[0024] FIG. 1 illustrates the functional scheme of a first embodiment example of a space propulsion system according to the invention;

[0025] FIG. 2 shows a perspective view of a component, a combustion chamber, of the propulsion system of FIG. 1;

[0026] FIG. 3 shows a plan view of the combustion chamber of FIG. 2;

[0027] FIG. 4 shows an additional perspective view of the combustion chamber of FIG. 2; and

[0028] FIG. 5 illustrates the functional scheme of a second embodiment example of a space propulsion system according to the invention 1 to 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] By referring to the figures, a space propulsion system is designated as a whole with 1. It comprises an electrolytic system 2 for dividing liquid water, transported in a container 3 split up into two branches, intended for gaseous hydrogen and oxygen, respectively.

[0030] The container 3 of the electrolytic system can constitute the only water tank available to the propulsion system, and this solution is suitable to satellites with minimum sizes, whereas for other larger-sized solutions and payload an additional tank feeding the container 3 can be provided.

[0031] The electrolytic system 2 then comprises an anode 4 and a cathode 5, arranged near or inside a respective branch of the container 3, which are subjected to an electric voltage produced by a battery 6, which, in turn, can be charged by a photovoltaic system existing aboard the space vehicle.

[0032] It is to be meant that the battery 6 is just a possible example of electric energy among the ones which can be used.

[0033] The gaseous oxygen and hydrogen bubble in the respective branches of the tank 3 at the anode 4 and the cathode 5 respectively. Then, they feed a respective tank of oxygen 7 and a respective tank of hydrogen 8 having reduced sizes, since the preservation of the propulsion fluid is implemented under the form of water in the liquid state, wherein hydrogen and oxygen □occupy a minimum space without requiring a complex confinement system.

[0034] As it is known, the water should at least be slightly dissociated in ions to allow the passage of electric current. To this purpose, it will include an adequate quantity of electrolyte, for example an acid or a dissolved salt.

[0035] The above-mentioned tanks are not strictly necessary but they can be useful should a higher gas injection than the productive capability of the electrolytic system be required, or for having flows characterized by higher pressures than those produced by the simple electrolytic process, or at last to obtain an immediate reaction by the propulsion system 1.

[0036] It further comprises a combustion chamber 10, which burns gaseous hydrogen and oxygen, with a helical inner motion so as to increase the residence time of the reagents and of the products so as to allow high combustion efficiencies in very small volumes.

[0037] The combustion chamber 10 comprises a cylindrical container 11 developing along a longitudinal axis having a first flat end 12 thereat there are two injection ducts therethrough oxygen and hydrogen are injected. The combustion chamber 10 further has cylindrical walls 13 extending from said first end 12 to a second end 14 wherein the discharge nozzle is positioned.

[0038] In particular, a first injection duct 15 is provided which is tangential to the cylindrical walls of the chamber 10 and which is arranged parallel to the plane of the first end 12. The position of the first injection duct 15 is so that it imposes a helical motion to the flow of oxygen and hydrogen which react therebetween.

[0039] Furthermore, a second injection duct 16 is provided which is perpendicular to the cylindrical walls of the chamber 10 and it is arranged parallel to the plane of the first end 12. The position of the second injection duct 16 is so that the inlet in the chamber 10 takes place near the inlet of the first duct 15, so that the gaseous flow injected through the first duct 15 intersects the gaseous flow injected through the second duct 16.

[0040] In the present example, the first injection duct 15 is fed by gaseous oxygen, whereas the second duct 16 is fed by gaseous hydrogen.

[0041] Considering that the available oxygen and hydrogen derive from the water electrolysis, they are provided with the exact required stoichiometric ratio. However, the interposition of tanks 7, 8 could require the presence of respective valves of oxygen 17 and hydrogen 18.

[0042] It is to be known that the flow of gaseous oxygen has a rate of flow by weight eight times higher than the rate of flow by weight of the gaseous hydrogen, due to the molar ratio between the two water components.

[0043] Therefore, the first injection duct 15 imposes to the gaseous flow resulting from the mixing of the two gases a helical path, with a helix which unwinds for the whole extension of the combustion chamber 10 as far as its second discharge end 14, by lengthening considerably the path of the combustion reaction and then even the related residence time of the reactant gases.

[0044] The cylindrical walls 13 of the cylindrical container 12 can show on their inner surface a deposition of catalytic material which produces an acceleration of the combustion reaction between oxygen and hydrogen. Preferably, the catalytic material mainly comprises Platinum.

[0045] Thanks to the catalytic material, the temperature for triggering the hydrogen oxidation reaction is lowered. In a preferred version of the device, such lowering, together with the lengthening of the combustion path, allows the ignition of the combustion reaction with development of flame without no outer ignition intervention is required.

[0046] Alternatively, the device can be provided with means for flashing an ignition spark in the combustion chamber 10.

[0047] In each case, it is meant that the combustion chamber is implemented in one single piece, and it has only the openings necessary to the injection and to the discharge.

[0048] Therefore, this combustion chamber exploits the fluid dynamics and the chemistry (catalysis) to increase to the maximum the residence time of the combustion and to reduce to the minimum the time of chemical kinetics. These solutions allow to simplify the construction of the combustion chamber by reducing, at the same time, the sizes thereof.

[0049] According to a variant, the combustion chamber 10 could be fed by a different combination of fuel and combustion agent, which could adapt to different situations and propulsion requirements, for example for satellites and space vehicles having larger sizes than those typical of the artificial satellites discussed previously: microsatellites, nanosatellites and picosatellites.

[0050] In case of vehicles with larger sizes, they could transport separate tanks of fuel and combustion agent, and in liquid phase, or under supercritical conditions, obtained by compression. These vehicles can include not only satellites but also space vehicles and launchers.

[0051] The typical combustion agent could be oxygen whereas the fuel could be a hydrocarbon like methane.

[0052] Solutions providing to feed liquid (or supercritical) fuels and combustion agents are also possible; for the first one it is possible to mention liquid hydrogen, kerosene, methanol or ethanol, dinitrogen tetroxide (hydrazine) whereas for the second ones it is possible to mention liquid oxygen, hydrogen peroxide, nitric compounds like nitric acid.

[0053] The combustion agent or the fuel requiring the larger range of flow expressed as mass per time unit is conveniently injected in the combustion chamber 10 by using the first injection duct 15, that is the tangential injection duct, whereas the combustion agent or the fuel requesting the smaller range of flow can be injected through the second injection duct 16, that is the perpendicular injection duct, so as to impose to their combination reacting in the combustion chamber a path with helical shape near the inner cylindrical surfaces of the combustion chamber 10.

[0054] At said second end 14 of the combustion chamber 10, the propulsion system comprises a sub-supersonic nozzle 20, as discharge of the combustion chamber 10, with a discharge duct which connects it thereto positioned tangential to the cylindrical walls of the chamber 10 and it is arranged parallel to the plane of the second end 14. The position of the discharge duct 19 is so that it receives the above-mentioned helical motion of the flow of the reactant gases which, in the starting example, are water vapour.

[0055] The direction of such flow to the discharge duct 19 is the correct one to minimize the pressure drops in this point of the circuit.

[0056] The shape of the supersonic nozzle 20 is so as to optimize the expansion of the hot gases existing inside the combustion chamber 10, therefrom it is possible to obtain the thrust necessary for the mission targets.

[0057] In the light of what described, it is important to underline that the transportation of liquid water involves very reduced volumes, it does not require any cunning device in terms of safety and it does not require tanks with particular technical features.

[0058] Moreover, the electrolytical process, for the division of water into gaseous hydrogen and oxygen, requires low amounts of energy, which can be obtained easily by means of solar cells even with very small sizes.

[0059] The gaseous hydrogen and oxygen are the pair of fuel/combustion agent having the highest performance; the electrolytical process divides the water into oxygen and hydrogen in the optimum stoichiometric proportions which, nominally, provide the best performance with consequent production of only water vapour outgoing from the chamber.

[0060] In addition to this, the catalytic deposition, together with the helical fluid dynamics motion inside the combustion chamber, allows to simplify, until totally eliminating, the ignition system, and to reduce to the minimum the required minimum sizes of the chamber in order to have an effective combustion.

[0061] Preliminary analyses detect, in order to obtain a thrust of 10 N, global sizes of the propulsion system smaller than 13 m m, with a micro-nozzle which allows to obtain high thrusts in very reduced sizes.

[0062] By referring to FIG. 5, a propulsion system is schematically illustrated and described wherein there is one single tangential injection duct, designated with 15, in the combustion chamber 10. Then it can be fed with a fuel-combustion agent mixture suitably selected based upon the operating needs of the satellite or of the vehicle.

[0063] In this example, the injection duct 15 is fed by an electrolyser 2 which was placed inside a tank 30 of water; the electrolyser 2 is fed electrically and produces gaseous H.sub.2 and O.sub.2 inside the tank 30.

[0064] The produced gases are kept separated from the liquid water by the spinning of the satellite, or of the vehicle, and then are introduced, already premixed in the right stoichiometric proportion, into the combustion chamber 10 through the single injection duct 15.

[0065] The ignition of the premixed gas can take place by means of an electric spark, or spontaneously by means of catalysis (for example platinum on the inner walls of the chamber). The catalysis in case can support the ignition by means of the spark as in the previous example.

[0066] To the above-described propulsion system, a person skilled in the art, with the purpose of satisfying additional and contingent needs, could introduce several additional modifications and variants, however all within the protective scope of the present invention, as defined by the enclosed claims.