JP7329242B2 - Fuel device, manufacturing method thereof, and hybrid rocket engine - Google Patents

Description

The present invention relates to a fuel system in which a solid fuel is combusted by being supplied with a fluid oxidant, a manufacturing method thereof, and a hybrid rocket engine.

A hybrid rocket engine employs boundary layer combustion in which a diffusion flame is generated only near the surface of a solid fuel based on a solid fuel and a liquid oxidant (see Patent Document 1). Since this boundary layer combustion is non-explosive, it can be expected to alleviate design, manufacturing, and operational restrictions due to the risks of unintended ignition and explosion in space development. The hybrid rocket engine is also capable of thrust control and has a simpler structure than the liquid rocket.
Therefore, in recent years, hybrid rocket engines have been applied to manned spacecraft such as the SpaceShipTwo, and are being studied for application to propulsion systems for microsatellites and the like.

JP 2012-87716 A

However, due to problems such as low thrust and combustion efficiency and a large amount of propellant residue (unburned residue), there is still no track record of a satellite equipped with a hybrid rocket engine being put into orbit. In recent years, there are signs of significant improvement in thrust increase and combustion efficiency. In addition, if the solid fuel consumption rate cannot be measured accurately, the performance of the hybrid rocket engine during combustion cannot be measured in real time, and performance stabilization and complicated thrust control cannot be achieved.

Under such circumstances, techniques for measuring the consumption rate of solid fuel in real time have been proposed, but none of the techniques have been established, and new techniques are required.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel device, a manufacturing method thereof, and a hybrid rocket engine that are capable of measuring the consumption rate of solid fuel using a new technique.

According to a first aspect of the present invention, there is provided a fuel system for achieving the above object, which includes a solid fuel, which is combusted by being given a fluid oxidant to generate an exothermic reaction, wherein the solid fuel is non-toxic. an electrode network that is conductive and made of a conductive material and shrinks as the solid fuel burns; measuring means for measuring a physical quantity of the electrode network; consumption rate calculation means for deriving the consumption rate of the solid fuel, wherein the electrode network has a lattice structure having a plurality of rod-shaped portions each formed of a conductive resin; As the solid fuel burns, the number of rod-shaped portions decreases, and the electrical physical quantity changes .

A hybrid rocket engine according to a second aspect of the invention that meets the above object has an engine case provided with an injector, and an oxidant supply means for supplying a fluid oxidant into the engine case via the injector. In the above, provided in the engine case, a non-conductive solid fuel, an electrode network formed of a conductive material and shrinking as the solid fuel burns, and a measuring means for measuring a physical quantity of the electrode network and consumption rate calculation means for deriving the consumption rate of the solid fuel based on changes in the measured values of the measurement means , wherein the electrode network comprises a plurality of rod-shaped portions each formed of a conductive resin. It has a lattice structure, and the number of rod-like portions of the lattice structure decreases as the solid fuel burns, and the electrical physical quantity changes.

A method of manufacturing a fuel device according to a third aspect of the present invention, which meets the above object, uses a three-dimensional printer to produce a solid fuel based on an insulating composite filament material and a conductive filament material, and shrinks as the solid fuel burns. the solid fuel is combusted with a fluid oxidizer, the electrode network shrinks as the solid fuel burns, and the electrode network shrinks as the solid fuel burns, and and a grid structure having a plurality of rod-shaped portions each formed of a conductive resin, wherein the grid structure reduces the number of rod-shaped portions as the solid fuel burns, and the electrical physical quantity obtain a variable fuel system.

A fuel device according to a first invention and a hybrid rocket engine according to a second invention are an electrode network formed of a conductive material and shrinking as a non-conductive solid fuel burns, and a physical quantity of the electrode network is measured. and a consumption speed calculation means for deriving the solid fuel consumption speed based on the change in the measurement value of the measurement means, so that the solid fuel consumption speed can be measured. is the engine.
A method for manufacturing a fuel device according to a third aspect of the present invention uses a three-dimensional printer to produce a solid fuel and an electrode that shrinks as the solid fuel burns, based on an insulating composite filament material and a conductive filament material. Through the step of forming each region of the network, the solid fuel is combusted given the fluid oxidant, resulting in a fuel system in which the electrode network shrinks with the combustion of the solid fuel, thus increasing the consumption rate of the solid fuel. Suitable for manufacturing non-traditional fuel systems that can be scaled.

1A and 1B are explanatory diagrams of a fuel system according to a first embodiment of the present invention; FIG. It is a block diagram showing the connection of the measuring means of the same fuel system. It is an explanatory view of a hybrid rocket engine according to a second embodiment of the present invention. It is a block diagram showing the connection of the measurement means and the oxidant supply means of the same hybrid rocket engine. It is an explanatory view of equipment used in the first experiment. It is explanatory drawing of the installation used by the 2nd experiment. It is explanatory drawing of the installation used by the 3rd experiment.

Next, specific embodiments of the present invention will be described with reference to the attached drawings for better understanding of the present invention.
As shown in FIGS. 1A, 1B, and 2, a fuel system 10 according to a first embodiment of the present invention has a solid fuel 11 which is a fluid oxidizer 12. A device that burns and causes an exothermic reaction, comprising an electrode network 13 formed of a conductive material and shrinking as the solid fuel 11 burns, and a measuring means 14 that measures the physical quantity of the electrode network 13 and consumption rate calculation means 15 for deriving the consumption rate of the solid fuel 11 based on changes in the measured values of the measurement means 14 . A detailed description will be given below.

The solid fuel 11 is non-conductive and has a cylindrical shape as shown in FIGS. 1(A) and 1(B). A through hole 16 into which the oxidant 12 flows is provided along the axis of the solid fuel 11 , and boundary layer combustion occurs within the through hole 16 . In the present embodiment, the solid fuel 11 contains at least one (one type) of thermoplastic elastomer, oxidant particles, and metal particles.

The electrode network 13 has a plurality of grid structures 17 arranged within the solid fuel 11 and is connected to a DC power supply 18 . Each lattice structure 17 has a plurality of rod-shaped portions 19. In each lattice structure 17, each rod-shaped portion 19 is parallel to the axis of the solid fuel 11 and arranged at equal pitches in the radial direction of the solid fuel 11. connected in parallel.
A lattice structure group in which a plurality of lattice structures 17 are radially arranged is arranged at the same position in the axial direction of the solid fuel 11 , and the plurality of lattice structure groups are arranged in the axial direction of the solid fuel 11 . located in different positions.

In the present embodiment, each rod-shaped portion 19 is made of a conductive resin containing at least one (one type) of graphene , graphite, carbon fiber, metal powder, and metal fiber. As the inner wall of the solid fuel 11 recedes (the through-hole 16 expands) due to combustion of the solid fuel 11 (boundary layer combustion), each lattice structure 17 is formed into a rod-like shape. As the number of portions 19 decreases, the electrical resistance value decreases in inverse proportion (that is, the electrical physical quantity changes). Therefore, the electrical resistance value of the lattice structure 17 is inversely proportional to the thickness of the solid fuel 11 (the distance from the inner wall to the outer wall).

As shown in FIG. 2, the electrode network 13 is connected to a measuring means 14 for measuring the electrical resistance value of the electrode network 13, and the measuring means 14 acquires the measured value of the measuring means 14 from the measuring means 14. A consumption speed calculation means 15 composed of a CPU, a memory, etc. is connected.
When the solid fuel 11 is burning, the measuring means 14 measures the electrical resistance value of the electrode network 13 supplied with a DC current from the DC power supply 18, and the consumption rate calculating means 15 calculates the measured value of the measuring means 14. That is, the consumption speed (decrease speed) of the solid fuel 11 is derived based on the amount of change per unit time of the electrical resistance value of the electrode network 13 .

Since the temperature of the lattice structure 17 rises by energization, each lattice structure 17 functions as a heater for warming the solid fuel 11 in addition to the function of changing the electrical resistance value of the entire electrode network 13 as the solid fuel 11 is consumed. It also has the function of

Next, a hybrid rocket engine 30 according to a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. In the hybrid rocket engine 30, the same components as those of the fuel system 10 are denoted by the same reference numerals, and detailed descriptions thereof are omitted (this point is the same below).
As shown in FIG. 3, the hybrid rocket engine 30 has an engine case 32 provided with an injector 31 and an oxidant supply means 33 for supplying a fluid oxidant 12 into the engine case 32 via the injector 31. ing.

The solid fuel 11 and all grid structures 17 are provided within the engine case 32 . The engine case 32 has an injector 31 at one end and a nozzle 34 at the other end. As shown in FIG. 4, the oxidant supply means 33 composed of CPU, memory, etc. derives the consumption rate of the solid fuel 11 based on the change in the electrical resistance value of the electrode network 13 measured by the measurement means 14. A consumption rate calculation means 15 is connected. The oxidant supply means 33 adjusts the supply amount of the oxidant 12 based on the consumption rate of the solid fuel 11 derived by the consumption rate calculation means 15 to control the exothermic reaction caused by the combustion of the solid fuel 11 .

The fuel system 10 also uses a three-dimensional (3D) printer to print the solid fuel 11 and the area of the electrode network 13 that shrinks as the solid fuel 11 burns, based on the insulating composite filament material and the conductive filament material. (In the present embodiment, each lattice structure 17) can be manufactured through a step of forming each. Note that not only the grid structure 17 but also the entire electrode network 13 may be made of a conductive resin containing at least one of graphene , graphite, carbon fiber, metal powder, and metal fiber.

In the embodiment described above, insulating thermoplastic filaments are used as the material of the solid fuel 11 and thermoplastic conductive filaments are used as the material of the electrode network 13 . In addition, thermoplastic binders and binders that double as fuel have also been used. Thermoplastic elastomers are used as thermoplastic materials, but are not limited to, for example, polymethyl methacrylate (PMMA), polyethylene, polysulfide (PS), polyvinyl chloride (PVC), polyurethane ( PU ), Polybutadiene acrylonitrile acrylate (PBAN), polybutadiene acrylic acid (PBAA), carboxyl-terminated polybutadiene (CTPB), hydroxyl-terminated polybutadiene (HTPB), nitrocellulose and the like may be used.

As the oxidizing agent, ammonium perchlorate (AP), ammonium nitrate (AN), potassium perchlorate (KP), nitronium perchlorate (NP) may be used.

Aluminum (Al), beryllium (Be), magnesium (Mg), and boron (B) can be used as metal fuels. Toluene diisocyanate (TDI), paraquinonedioxime (PQD), etc. may be used as curing and crosslinking agents.

As a binding additive, 1,2-tris(2-methyladezilinyl) phosphine oxide or the like may be used. As plasticizers, dioctyl adipate, nitroglycerin , trimethylolethane trinitrate (TMETN), triethylene glycol dinitrate (TEGDN), diethylene glycol dinitrate (DEGDN), diethyl phthalate (DEP), triacene (TA ), polyurethane (PU), etc. may be used. Further, ferric oxide, lead salicylate (PbSa), copper salicylate (CuSa), etc. may be used as a burning rate catalyst.

Fullerene, carbon black, graphite, graphene, carbon fiber, carbon nanotube, metal filler, and the like can be used as the conductive material.

Next, experiments conducted on the present invention will be described.
In the first experiment, the solid fuel 11 and the grid structure 17 were fabricated as shown in FIG. 5 using a conductive resin mixed with graphene and an insulating resin as raw materials and using a three-dimensional printer. The fabrication was performed after verifying the dimension (pitch) L1 between the lattice structures 17 in the axial direction of the solid fuel 11 and the length L2 of the rod-like portions 19 . Then, the injector 31, the nozzle 34, and other parts constituting the hybrid rocket engine were prototyped. This confirms that a three-dimensional printer can be used to fabricate solid fuels and lattice structures, as well as other parts.

In the second experiment, as shown in FIG. 6, the consumption rate of the solid fuel 11 was measured for the fuel device 40 in which the lattice structures 17 were arranged on both sides of the through-hole 16 centering on the through-hole 16 of the solid fuel 11. verified that it is possible.
While the solid fuel 11 is burning, the voltage of one grid structure 17 is measured with a voltmeter 41, and the thickness of the solid fuel 11 in the region where the other grid structure 17 is provided is measured using an ultrasonic thickness gauge 42. measured. A voltmeter 41 and an ultrasonic thickness gauge 42 are connected to a computer 44 via a data logger 43, and the voltage value of one lattice structure 17 is compared with the measurement value of the ultrasonic thickness gauge 42 to determine whether the solid fuel 11 It was confirmed whether the measurement of the consumption rate of

In the third experiment, as shown in FIG. 7, in a fuel device 50 having lattice structure groups provided at different positions in the axial direction of the solid fuel 11, the solid fuel 11 was combusted. The consumption rate of the solid fuel 11 was measured in real time by measuring the voltage of the grid structure 17 with the voltmeter 41 over the entire axial direction of the solid fuel 11 . In this experiment, in addition to the voltmeter 41 corresponding to each lattice structure 17, a flow meter 53 attached to an introduction pipe 52 for supplying a gaseous oxidant to the through-hole 16 via an injector 31, A thermometer 54 for measuring temperature and a pressure gauge 55 for measuring pressure on the gas blowing side of the injector 31 are provided. The measured values of each voltmeter 41 , flow meter 53 , thermometer 54 and pressure gauge 55 were collected by computer 44 via data logger 43 .

Then, after the combustion treatment of the solid fuel 11, the shape of the solid fuel 11 is measured by a shape measurement method based on water level measurement using a laser rangefinder, and the thickness of the solid fuel 11 after combustion treatment (distance from the inner wall to the outer wall) was derived, and based on the real-time measurement of the consumption rate of the solid fuel 11, it was confirmed whether the thickness of the solid fuel 11 was accurately measured.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all modifications of conditions that do not deviate from the gist of the present invention are within the scope of the present invention.
For example, the electrode network may shrink as the solid fuel burns and may not have a grid structure.
Moreover, the physical quantity of the electrode network measured by the measuring means is not limited to the electrical resistance value, and may be, for example, the voltage value.
Furthermore, the conductive resin forming the rod-shaped portions of the grid structure may not contain graphene , graphite, carbon fiber, metal powder or metal fiber, and the solid fuel may be thermoplastic elastomer, oxidant particles or metal It does not have to contain particles.

INDUSTRIAL APPLICABILITY According to the present invention, a simple fuel flow measurement system that can be mounted on a rocket body can be realized. This method can be applied not only to simple cylindrical solid fuel, but also to hybrid rockets with complex solid fuel shapes, such as CAMUI hybrid rockets and end-burning hybrid rockets, by devising the shape of the rudder resistance structure. be. Combining this measurement system with hybrid rocket thrust, acid-fuel ratio control technology, and reignition technology will realize a hybrid rocket engine system that is highly safe and capable of advanced control. This will greatly reduce security risks in various aspects of space development, such as rocket launches and microsatellites, and dramatically reduce the time, manpower, technology, and aircraft costs. It can contribute to the reduction of technology maintenance costs.
More specifically, it will be possible to research and develop a vertical take-off and landing hybrid rocket that can automatically control thrust while maintaining high efficiency and has low explosiveness. It can also be applied to hybrid rocket thrusters for piggyback micro-satellites that are capable of advanced control. Since it becomes possible to grasp the shape of the solid fuel during coasting, it is particularly useful for missions that require multiple flame-extinguishing and re-ignition, such as changing the orbital surface, as it will lead to grasping the mass characteristics of the propulsion system. It is believed that there is.

10: Fuel device, 11: Solid fuel, 12: Oxidant, 13: Electrode network, 14: Measuring means, 15: Consumption rate calculating means, 16: Through hole, 17: Grid structure, 18: DC power supply, 19: Rod-shaped part 30: Hybrid rocket engine 31: Injector 32: Engine case 33: Oxidant supply means 34: Nozzle 40: Fuel device 41: Voltmeter 42: Ultrasonic thickness gauge 43: Data Logger, 44: Computer, 50: Fuel device, 52: Introduction pipe, 53: Flow meter, 54: Thermometer, 55: Pressure gauge

Claims (9)

In a fuel system having a solid fuel that is combusted by a fluid oxidant to produce an exothermic reaction,
the solid fuel is non-conductive,
an electrode network formed of an electrically conductive material and shrinking as the solid fuel burns;
a measuring means for measuring a physical quantity of the electrode network;
Consumption speed calculation means for deriving the consumption speed of the solid fuel based on changes in the measured values of the measurement means ,
The electrode network has a lattice structure having a plurality of rod-shaped portions each formed of a conductive resin, and the number of the rod-shaped portions of the lattice structure decreases as the solid fuel burns, A fuel device characterized by a change in electrical physical quantity . 2. A fuel system according to claim 1 , wherein said conductive resin comprises at least one of graphene , graphite, carbon fiber, metal powder and metal fiber. 3. A fuel system according to claim 1 or 2 , wherein the solid fuel comprises at least one of thermoplastic elastomer, oxidant particles and metal particles. In a hybrid rocket engine having an engine case provided with an injector and an oxidant supplying means for supplying an oxidant of a fluid into the engine case via the injector,
a non-conductive solid fuel provided within the engine case;
an electrode network formed of an electrically conductive material and shrinking as the solid fuel burns;
a measuring means for measuring a physical quantity of the electrode network;
Consumption speed calculation means for deriving the consumption speed of the solid fuel based on changes in the measured values of the measurement means ,
The electrode network has a lattice structure having a plurality of rod-shaped portions each formed of a conductive resin, and the number of the rod-shaped portions of the lattice structure decreases as the solid fuel burns, A hybrid rocket engine characterized by changes in electrical physical quantities . 5. A hybrid rocket engine according to claim 4 , wherein said conductive resin includes at least one of graphene , graphite, carbon fiber, metal powder and metal fiber. 6. A hybrid rocket engine according to claim 4 or 5 , wherein said solid fuel comprises at least one of thermoplastic elastomer, oxidant particles and metal particles. Using a three-dimensional printer, based on the insulating composite filament material and the conductive filament material, through the step of forming a solid fuel and an electrode network region that shrinks as the solid fuel burns, the solid fuel is a grid that is given a fluid oxidant and burns, the electrode network shrinks as the solid fuel burns, and the electrode network comprises a plurality of rod-shaped portions each formed of a conductive resin; A method of manufacturing a fuel device, comprising: obtaining a fuel device having a structure, wherein the number of rod-shaped portions of the lattice structure decreases as the solid fuel burns, and the electrical physical quantity changes. . 8. The method of manufacturing a fuel device according to claim 7 , wherein part or all of said electrode network is made of a conductive resin containing at least one of graphene , graphite, carbon fiber, metal powder and metal fiber. A method of manufacturing a fuel device, characterized by: 9. A method of manufacturing a fuel system according to claim 7 or 8 , wherein said solid fuel includes at least one of thermoplastic elastomer, oxidant particles and metal particles.

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