FR3065202A1 - SPATIAL THRUSTER - Google Patents

Abstract

A chemical-electric hybrid space propulsion system comprising a chemical propulsion module and an electric propulsion module. The chemical propulsion unit includes an electric pump configured to pump a fuel and / or an oxidant into a combustion chamber and the electric propulsion unit includes an electrical power system for ionizing and ejecting atoms of a propellant mass. The electric pump is connected to the power supply system to be supplied with electrical energy. The invention is of interest to all actors active in the field of space propulsion. The proposed system makes it possible to optimize the mission performance (duration and mass of payload) of an orbital stage or of a top stage of launcher, this at the cost of a limited system complexity (thanks to the connection between the chemical propellant bay and electric).

Description

(54) SPATIAL PROPELLER (57) a hybrid chemical-electric space propulsion system comprising a chemical propulsion module and an electric propulsion module. The chemical propulsion module includes an electric pump configured to pump fuel and / or oxidant into a combustion chamber and the electric propulsion module includes an electrical power system for ionizing and ejecting atoms from a propellant mass. The electric pump is connected to the electric power system to be supplied with electric energy.

The invention is of interest to all actors active in the field of space propulsion. The proposed system makes it possible to optimize the mission performance (duration and payload mass) of an orbital stage or an upper stage of the launcher, at the cost of a limited system complexity (thanks to the connection between chemical propellant bay and electric).

Technical Field [0001] In general, the invention relates to a chemical-electric hybrid space propulsion system.

Technological background Space systems using electric propulsion are currently very studied, for example, for a mission of exploration and human colonization on Mars, or for any other mission requiring orbital stages to long operational life. Indeed, long missions such as the exploration of planets or other celestial bodies (asteroids, comets, etc.) have drastic energy needs and electric propulsion, very economical in fuel, makes it possible to best respond to these needs. However, electric propulsion remains very slow compared to more conventional chemical propulsion.

A NASA study "Human Exploration of Mars Design Referenced Architecture 5.0" (NASA / SP-2009-566-ADD2, March 2014, Bret G. Drake and Kevin D.

Watts, editors) conceptually analyzes, based on current technologies, different possible approaches for a mission to Mars. In particular, this study lists (section 3, p 152: "Advanced ln-space Transportation") the different space propulsion systems available such as cryogenic nuclear propulsion, nuclear electric propulsion, solar electric propulsion and chemical propulsion.

The objective of the present invention is to improve existing solutions for space propulsion.

General description of the invention One aspect of the invention relates to a hybrid chemical-electric space propulsion system. The system comprises a chemical propulsion module (including one or more rocket motors, chemical propellant tanks, the installation for delivering the propellants from the tanks to the rocket motors, etc.) comprising an electric pump configured to pump fuel and / or an oxidizer in a combustion chamber (opening into a nozzle). The hybrid space propulsion system also includes an electric propulsion module including a power supply system for ionizing and ejecting atoms from a propellant mass. The propulsion system electric pump is connected to the power supply system of the electric propulsion module to be supplied with electrical energy. The electric propulsion module can also include solar panels, propellant tanks and one or more electric propellants (eg plasma or ionic motors). The chemical-electric hybrid space propulsion system therefore allows a transfer of electrical energy between the electrical propulsion module and the chemical propulsion module. Energy can be transferred at certain times during a mission. Depending on the configuration of the chemical-electric hybrid space propulsion system, the transfer of electrical energy can be one-way from the electric propulsion module to the chemical propulsion module or else bidirectional. In the second case, the electric pump is driven by an electric motor-generator.

In the context of this document, a space propulsion system is a propulsion system intended to propel a spacecraft being in space. The chemical-electric hybrid space propulsion system according to one aspect of the invention is particularly suitable for being integrated p. ex. in the upper stage of a launcher or in a space tug that performs several long missions in orbit.

Chemical propulsion makes it possible to propel a spacecraft thanks to the ejection of a propellant at high temperature, produced by an exothermic reaction between a fuel and an oxidizer (combustion). The combustion takes place in a combustion chamber and the reaction product (s) are then expanded and accelerated in a nozzle adjoining the combustion chamber.

Generally, the fuel and the oxidant (propellants) are injected at high pressure into the combustion chamber for their combustion. The propellant pressure may be in a range from several bars to several hundred bars (eg between 10 and 400 bars), depending on the type and power of the rocket engine.

The electropump makes it possible to pump the fuel and / or the oxidant and to put the fuel and / or the oxidant at the pressure desired for injection into the combustion chamber. For the purposes of this document, the term “electric pump” designates a pump or a set of pumps which are driven by one or more electric motors.

The electric propulsion module (more particularly the electric propellant) uses electric energy, supplied by the electric power system, to propel the spacecraft. Indeed, the electric propulsion module (more particularly the electric propellant) is configured to ionize and eject, thanks to the electric energy supplied by the electric power system, the atoms of a propellant mass in order to propel the machine spatial. Ionization can be done, for example, by the crossing of an electron cloud, by an electrical discharge, by a high frequency source, by contact, by electromagnetic waves, etc. Ejection can be achieved, for example, by an interaction between the ions and an electric field and / or a magnetic field.

According to one embodiment, the chemical propulsion module comprises a turbine configured to recover part of the combustion energy generated in the combustion chamber.

According to one embodiment of the invention, the chemical propulsion module comprises a system for cooling the combustion chamber and / or the nozzle, in which part of the oxidant and / or of the fuel is directed towards the walls of the combustion chamber and / or the nozzle in order to cool them. The combustion energy recovered by the oxidizer and / or hot fuel can then be used to drive the turbine. Alternatively or additionally, the chemical propulsion module can comprise a precombustion chamber, in which part of the propellants react and release energy which can operate the turbine and / or preheat the propellants.

According to a preferred embodiment of the invention, the electric pump comprises a motor-generator mechanically coupled to the turbine for injecting electrical energy into the electrical supply system. In this context, the expression "motor-generator" designates an electrical machine which can function as a generator (converting mechanical energy into electrical energy) and as a motor (converting electrical energy into mechanical energy). The turbine is used to power the electric motor-generator of the electric pump in power generator mode, and to transmit electric power from the chemical propulsion module to the electric propulsion module.

According to one embodiment, the power supply system comprises a battery (or storage battery).

According to one embodiment, the electrical supply system comprises a module for the distribution and management of electrical energy.

In an embodiment comprising a battery and a module for distributing and managing electrical energy, the battery is preferably connected to the module for distributing and managing electrical energy. The electrical power distribution and management module can be configured to use the battery as a buffer battery.

îo In a preferred embodiment, the chemical propulsion module comprises a fuel tank and an oxidizer tank and the electric propulsion module comprises a propellant tank. Preferably, the propulsion system comprises a cryogenic compartment common to the tanks of the chemical and electrical propulsion modules. The common cryogenic compartment can optionally be connected to the electrical supply system to be supplied with electrical energy.

According to one embodiment, the fuel can be selected from the group consisting of: oxygen (liquid or gaseous), T-Stoff or other compound of hydrogen peroxide, nitrogen peroxide and nitric acid. The fuel is preferably selected from the group consisting of: hydrogen (liquid or gaseous), hydrocarbon (eg methane, ethane, etc.) or mixture of hydrocarbons (eg kerosene), C-Stoff or other ethanol compound, hydrazine and hydrazine derivative compound. Other oxidant-fuel couples are also possible.

Kerosene is a mixture of hydrocarbons containing alkanes (C _n H2n + 2) of chemical formula ranging from C10H22 to C14H30. Hydrazine (diazane) has the chemical formula N2H4 (semi-developed formula H2N-NH2). T-Stoff is composed of an oxidizing fraction with 80% hydrogen peroxide H2O2 and 20% water H2O and stabilizers (phosphoric acid, sodium phosphate and 8-hydroxyquinoline). CStoff is a mixture of approximately 57% methanol CH3OH and 43% hydrazine hydrate

Ν2Η4Ή2Ο (mass fractions) with a catalyst K3 [Cu (CN) 4] (tripotassium tetracyanocuprate).

According to one embodiment, the propellant mass comprises atoms selected from the group consisting of the following species: xenon, krypton, bismuth, argon, iodine, magnesium, zinc. This list is not exhaustive but indicates some preferred species. According to a preferred embodiment, exactly one of these species constitutes the propellant mass.

Optionally, the chemical propulsion module of the propulsion system comprises an electrical actuator system, which allows the orientation of the nozzle, connected to the electrical supply system to be supplied with electrical energy. Such a “vector push module” is also called “TVC” (acronym of the English term “thrust vector control”). It will be appreciated that the use of an electric TVC makes it possible to greatly reduce the complexity compared to a hydraulic TVC usually used in a chemical propulsion module.

Preferably, the power supply system includes one or more solar panels.

According to a preferred embodiment, the propulsion system described above is integrated in a spacecraft. According to embodiments, the spacecraft can be a space tug, the upper stage of a launcher, a space probe or a space capsule. A space probe is an unmanned spacecraft launched into space to study different celestial objects (Sun, planets, ...). A space capsule is a simple spacecraft manned by a crew.

The proposed space propulsion system makes it possible to optimize the mission performance (in terms of duration and payload mass) of an orbital stage or of an upper stage of a launcher, at the cost of a limited system complexity ( thanks to the connection between the chemical and electric propellants). With such a system, the mission of the orbital stage would include alternating phases propelled in chemical mode and phases propelled in electric mode. If electric propulsion continues to provide the majority of the total mission impulse (more than 60%), the average specific impulse remains close to the high values which are reached by electric propulsion (2000 sec and more). Chemical propulsion can be used during parts of the mission during which the acceleration has a high added value (start of the mission where gravity is the strongest, crossing of Van Hallen belts, maneuvers in the perigee, meeting with a satellite, etc.). Chemical propulsion will also reduce the total duration of the mission.

BRIEF DESCRIPTION OF THE DRAWINGS Other particularities and characteristics of the invention will emerge from the detailed description of certain advantageous embodiments presented below, by way of illustration, with reference to the appended drawings which show:

Fig. 1: a hybrid chemical-electric space propulsion system according to a first embodiment of the invention; and

Fig. 2: a chemical-electric hybrid space propulsion system according to a second embodiment of the invention.

Detailed description of several embodiments of the invention îo [0026] FIG. 1 illustrates a chemical-electric hybrid space propulsion system of a space tug, according to a first preferred embodiment of the invention. The propulsion system 10 comprises a chemical propulsion module 12 and an electric propulsion module 14. The vertical dotted line 16 schematically delimits the elements of the chemical propulsion module 12 from the elements of the electric propulsion module 14.

A tug is a type of orbital stage, that is to say a stage which spends its entire operational life in space. It can be designed to interact with other satellites and carry out, for example cooperative meetings, captures, transport, desorbiting maneuvers, exchanges of propellants and / or energy.

Generally, the propulsion of such a tug is electric, having a high specific impulse (Isp) (of the order of 2000 seconds for an electric thruster in Krypton). The high Isp reflects the fact that electric propulsion consumes relatively little propulsive mass. An aspect sometimes considered as a disadvantage of electric thrusters is the fact that they generate only a relatively weak thrust (of the order of Newton for an electric thruster with Hall effect in Xenon).

The propulsion system 10 incorporates, in addition, a chemical propulsion. Chemical propulsion has a moderate Isp (of the order of 350 seconds for an oxidant-fuel liquid oxygen-methane couple) reflecting the fact that it consumes a lot of combustion reagents. On the other hand, the thrust of a chemical propellant is significant (of the order of 5 kN for an oxidant-fuel-liquid oxygen-methane couple). Chemical propulsion is therefore ideal during maneuvers in which acceleration has a high added value (e.g. in an area where gravity is stronger, when crossing Van Hallen belts, during perigee maneuvers , during meetings, etc.).

The propulsion system 10 "marries" the chemical propulsion with the electric propulsion. The system 10 makes it possible to bypass certain aspects considered to be disadvantageous linked to each propulsion, used alone. The space tug can then be propelled by chemical propulsion or electric propulsion according to the needs of its mission. Typically, electric propulsion is active during a large part of the tug's mission (eg 60% to 99% of the total mission impulse) and chemical propulsion takes over during maneuvers in which the acceleration has a high added value (eg 1% to 40% of the total mission impetus). In this case, the average Isp of system 10 will be close to the Isp of the electric thruster but the total duration of a mission will be reduced compared to a propulsion system comprising only one electric propellant.

The chemical propulsion module 12 propels the space tug into space through the ejection of the products of combustion of an oxidizer with a fuel into space. The combustion takes place in a combustion chamber 18 into which the propellants are injected. The combustion products are ejected through the nozzle 20 adjoining the combustion chamber.

The chemical propulsion module 12 comprises a fuel tank 22 and an oxidizer tank 24. The fuel and the oxidizer are pumped into the combustion chamber 18 by an electric pump 26, comprising a fuel pump 28 and a pump oxidizer 30. A fuel control valve 32 and an oxidizer control valve 34 are placed downstream (or upstream) of the pumps 28, 30 and upstream of the combustion chamber 18 in order to finely regulate the pressure and the flow rate propellants.

In addition (optional), the chemical propulsion module 12 comprises an electric vector thrust module (TVC) 36 allowing to direct the ejection of the exhaust gases into space in order to control the angular speed of the space tug. The electric vector thrust module 36 orients the nozzle 20 to guide the flow of exhaust gas. In another embodiment, instead of orienting the nozzle 20, the electric vector thrust module 36 orients deflector panels in order to guide the flow of exhaust gases.

The electric propulsion module 14 propels the space tug by the ejection of ionized atoms. It comprises a propellant reservoir 38 connected to an electric propellant 40. The propellant 40 can be an electrothermal propellant (eg a resistojet or an arcjet motor), an electromagnetic motor (eg a magnetoplasmadynamic, a ponderomotive force motor or pulsed plasma motor) or electrostatic motor (eg, field emission motor, ion grid motor, RIT motor (from the English term "Radiofrequency ionization thruster") or motor Hall Effect) or any other motor suitable for an electric thruster.

The propellant 40 of the electric propulsion module 14 is supplied with electrical energy from an electrical supply system 42.

The power supply system 42 includes a distribution module and management of electrical energy 44 ("Power Management And Distribution" (PMAD) in English), a battery 46 and solar panels 48. Solar panels 48 collect the solar energy and transform it into electrical energy, which can possibly be stored in the battery 46. Indeed, the battery 46 makes it possible to store the surplus energy to redistribute it if necessary, p. ex. during eclipse phases or in case of higher energy consumption.

In accordance with one aspect of the invention, the electropump 26 is connected to the power supply system 42, in particular to the PMAD 44 to be supplied with electrical energy. The electrical energy supplied by the PMAD 44 to the electropump 26 supplies the motor 50 thereof. The engine 50 is configured to drive the fuel pump 28 and the oxidizer pump 30.

It will be appreciated that the propulsion system 10 establishes a bridge between the chemical propulsion and the electric propulsion producing a synergistic effect between these two propellants. Indeed, it performs a hybridization between the chemical propulsion and the electric propulsion because the electric power supply system 42 of the electric propellant 14 supplies elements of the chemical propellant 12, in particular the electric pump 26.

In the embodiment shown in FIG. 1, the motor 50 of the electric pump 26 drives the pumps 28, 30 through a mechanical transmission system, here illustrated by a transmission shaft 52.

It will be appreciated that other configurations of the electric pump are possible.

For example, the electric pump 26 could be replaced by electric pumps with separate drives for fuel and for oxidizer.

The vector thrust module 36 of the chemical propulsion module 12 is connected to the electric power system 42 of the electric propellant 14 to be supplied with electric energy.

îo In the illustrated embodiment, the fuel tanks 22 and oxidizer 24 and the propellant tank 38 share the same cryogenic compartment 54. This configuration reduces the impact of the use of cryorefrigerators for chemical propellants on electrical energy consumption. The use of these cryorefrigerators is optional. If mission requirements allow, fuel, oxidizer, and propellant can be stored at non-cryogenic temperatures.

[0042] FIG. 2 illustrates a propulsion system of a space tug according to the second preferred embodiment of the invention. The propulsion system of the space tug is similar to the propulsion system illustrated in FIG. 1. However, it differs from this in that it further comprises a turbine 56, a cooling circuit 58 of the combustion chamber 60 and possibly of the nozzle 62. In addition, the motor of the electric pump is replaced by motor-generator 64.

It will be appreciated that the embodiment illustrated in FIG. 2 converts part of the combustion energy into electrical energy usable by the electric thruster. It will also be appreciated that, according to this preferred embodiment, the hybridization between the chemical propulsion and the electric propulsion allows the realization of a bidirectional transfer of energy between the two propellants.

Part of the fuel (or oxidant) is directed into the cooling circuit 58 as a heat transfer fluid in order to recover part of the combustion energy. The flow of fuel (or oxidant) injected into the cooling system 58 is controlled by a control valve 66.

After having absorbed part of the heat, the hot heat transfer fluid drives the turbine 56. The mechanical energy produced by the turbine 56 can be used to drive the pumps 72, 74 and / or by the motor generator 64 for generate electrical energy. This electrical energy is made available to the PMAD 68 of the electrical supply system 70.

The part of the fuel or oxidizer which has driven the turbine can be injected into the combustion chamber 62 or be evacuated in another way.

It will also be appreciated that the surface of the solar panels could be reduced compared to that of a space tug (or any other spacecraft) without chemical propulsion thanks to the synergy between the chemical propellant and the electric propellant.

While particular embodiments have just been described in detail, those skilled in the art will appreciate that various modifications and alternatives to those can be developed in the light of the overall teaching provided by the present disclosure of the invention. Consequently, the specific arrangements and / or methods described herein are intended to be given by way of illustration only, without the intention of limiting the scope of the invention.

Claims (15)

Claims 1. A hybrid chemical-electric space propulsion system, characterized in that it comprises a chemical propulsion module comprising an electric pump configured to pump fuel and / or an oxidant into a combustion chamber; and an electric propulsion module comprising a power supply system for ionizing and ejecting atoms from a propellant mass; in which the electric pump is connected to the electric power system îo of the electric propulsion module to be supplied with electric energy. 2. The propulsion system according to claim 1, in which the chemical propulsion module comprises a turbine configured to recover part of the combustion energy generated in the combustion chamber. 3. The propulsion system according to claim 2, in which the electric pump 15 includes a motor generator coupled to the turbine for injecting electrical energy into the electrical supply system. 4. The propulsion system according to any one of claims 1 to 3, wherein the power supply system comprises a battery. 5. The propulsion system according to any one of claims 1 to 4, in 20 which the power supply system comprises a module for distribution and management of electrical energy. 6. The propulsion system according to any one of claims 1 to 5, in which the chemical propulsion module comprises a fuel tank and an oxidizer tank and in which the electric propulsion module 25 includes a propellant reservoir. 7. The propulsion system according to claim 6, comprising a cryogenic compartment common to the reservoirs of the chemical and electrical propulsion modules. 8. The propulsion system according to any one of claims 1 to 7, in Wherein the oxidant is selected from the group consisting of: oxygen, TStoff or other compound of hydrogen peroxide, nitrogen peroxide and nitric acid and wherein the fuel is selected from the group consisting of: hydrogen, hydrocarbon or mixture of 'hydrocarbons, C-Stoff or other ethanol compound, hydrazine and hydrazine derivative compound. 9. The propulsion system according to any one of claims 1 to 8, in 5 which the propellant comprises atoms selected from the group consisting of the following species: xenon, krypton, bismuth, argon, iodine, magnesium, zinc. 10. The propulsion system according to any one of claims 1 to 9, in which the chemical propulsion module comprises an electrical vector push module connected to the electrical supply system to be supplied with electrical energy. 11. The propulsion system according to any one of claims 1 to 10, wherein the electrical power system comprises one or more solar panels. 15 12. A spacecraft comprising a propulsion system according to any one of claims 1 to 11. 13. The spacecraft according to claim 12, the spacecraft being a spacecraft. 14. The spacecraft according to claim 12, the spacecraft being an upper stage 20 of a launcher. 15. The spacecraft according to claim 12, the spacecraft being a space probe or a space capsule.