JP2022087139A - Grain for hybrid rockets and method for producing the same - Google Patents

Abstract

To provide a grain for hybrid rockets that achieves an improved thrust during combustion while maintaining ease of production.SOLUTION: A grain for hybrid rockets 10 has a plural layers of solid fuel 11 laminated in a radial direction in a cross-sectional circle of the grain 10, and a combustible partition 12 for separating the layers of the solid fuel 11. The partition 12 is composed of a one-side sheet having a tabular sheet and a wavy sheet joined together at a contact point of both.SELECTED DRAWING: Figure 2

Description

The present invention relates to a grain (solid fuel product) for a hybrid rocket and a method for producing the same.

Conventionally, three types of rocket engine methods are mainly known: a liquid fuel rocket, a solid fuel rocket, and a hybrid rocket. In order for a rocket to gain thrust in a space with low oxygen concentration, it needs fuel and an oxidizer to burn it. A liquid fuel rocket has a liquid fuel and an oxidant, a solid fuel rocket has a solid fuel and an oxidant, and a hybrid rocket has a solid fuel and a liquid oxidant. In the present specification, this solid fuel product as a whole is referred to as "grain".

One or more combustion spaces are formed in the grain for the hybrid rocket. The hybrid rocket can obtain thrust by supplying a liquid oxidant to the combustion space of the grain, burning the grain, and injecting the gas generated by the combustion phenomenon from the nozzle. Since the solid fuel and the liquid oxidant are structurally separated in the hybrid rocket, it is easier to manufacture than the liquid fuel rocket and the solid fuel rocket, and the solid fuel and the liquid oxidant are easily managed. It has the advantage of high safety and easy control of combustion. On the other hand, a hybrid rocket has a disadvantage that the specific impulse (impulse of thrust obtained by using a unit weight propellant) is lower than that of a liquid fuel rocket, for example, and it is difficult to generate thrust. In this way, the hybrid rocket is easy to manufacture and has excellent safety and controllability, but it has a low thrust, so it can be used as an engine for a sounding rocket that measures data during ballistic flight, for example. many.

As described above, the hybrid rocket has the disadvantage of low thrust, but as a device to compensate for this, for example, as disclosed in Patent Document 1 and Patent Document 2, the solid fuel itself is spirally wound. It is known to form and form voids between each layer. It is said that by providing a gap between the layers of the solid fuel wound in a spiral shape in this way, the combustion efficiency of the solid fuel can be improved and a large thrust can be generated.

Japanese Unexamined Patent Publication No. 55-144494 Japanese Unexamined Patent Publication No. 55-144495

By the way, in the invention described in Patent Document 1, a solid fuel of a corrugated plate is laminated and integrated on one side of a solid fuel of a flat plate, and the solid fuel is wound in a spiral shape, but has a certain thickness (for example, 1 mm). It is difficult to process a certain solid fuel itself into a corrugated plate shape and integrate it with a flat plate, and there is a problem that the merit of a hybrid rocket, which is easy to manufacture, is impaired. For example, the contact area between the flat plate and the corrugated sheet must be adhered with a low-temperature adhesive, but when such an adhesive is used, the shape of the corrugated sheet must be maintained until the adhesive is completely solidified. However, there is a problem that it is difficult to efficiently and continuously produce a grain in which a flat plate and a corrugated plate are integrated.

Further, in the invention described in Patent Document 2, a protrusion-shaped spacer is formed on one side of a flat plate-shaped solid fuel, and the solid fuel is wound in a spiral shape. There is a problem that sufficient voids in each layer cannot be secured. In fact, it is not possible to maintain the voids of each layer as in Patent Document 1 only by forming the protruding spacers formed on the surface of the solid fuel as in Patent Document 2. As a result, in the structure of Patent Document 2, it is considered that the effect of improving the combustion efficiency is limited.

Therefore, it is a main object of the present invention to improve the combustion efficiency of the grain and the thrust at the time of combustion while maintaining the ease of manufacturing in the grain for a hybrid rocket.

As a result of diligent studies on means for solving the problems of the prior invention, the inventor of the present invention forms a partition wall with a simple one-stage sheet in which a flat plate sheet and a wavy sheet are joined, and the partition wall creates voids between layers of solid fuel. By forming it, we obtained the finding that it is possible to provide grains that are easy to manufacture and have high fuel efficiency. Then, the present inventor came up with the idea that the problems of the conventional invention could be solved based on the above findings, and completed the present invention. Specifically, the present invention includes the following configurations or steps.

A first aspect of the invention relates to a grain 10 for a hybrid rocket. The grain 10 according to the present invention includes a solid fuel 11 and a partition wall 12. The grain 10 has a substantially cylindrical shape, and one or a plurality of combustion spaces S are formed along the central axis A thereof. The "substantially cylindrical shape" is a cylindrical shape (see FIG. 6) having a closed outer circumference and a substantially cylindrical shape in which the sheet is spirally wound (see FIG. 2 etc.). include. The solid fuel 11 is laminated over a plurality of layers in the radial direction R in the cross-sectional circle of the grain. The solid fuel may be integrated or may be separated into a plurality of solid fuels. The partition wall 12 is a flammable material that separates each layer of the solid fuel 11 in the radial direction R of the grain 10. The partition wall 12 is composed of a single-stage sheet in which a flat plate-shaped sheet 13 and a wavy sheet 14 are joined at a contact point 15 of both. The solid fuel 11 and the partition wall 12 may be made of different materials or may be made of the same material.

As described above, the grain 10 according to the present invention includes a flammable partition wall 12 composed of a one-stage sheet in addition to the solid fuel 11. In this respect, the grain 10 according to the present invention is different from the grain described in Patent Document 1 in which the solid fuel itself has only a one-stage structure in which a flat plate and a corrugated plate are integrated. In the present invention, the one-stage structure partition wall 12 has a gap V formed in a portion where the flat plate sheet 13 and the wavy sheet 14 are separated from each other. Therefore, by inserting the partition wall 12 between the solid fuels 11, the solid fuel The combustion efficiency between 11 can be improved. That is, in order to improve the thrust of the grain 10 during combustion, it is important to increase the speed at which the combustion surface of the solid fuel 11 recedes from the center of the grain 10 toward the outer periphery. At this time, by arranging the partition wall 12 in which the gap V is formed by the one-stage structure between the layers of the solid fuel 11, the recession speed of the solid fuel 11 can be increased. Further, since the flat plate-shaped sheet 13 and the corrugated sheet 14 constituting the partition wall 12 do not need to have a thickness, each of them can be made into a relatively thin sheet shape. Therefore, the one-stage sheet obtained by joining the flat plate-shaped sheet 13 and the corrugated sheet 14 can be easily processed and manufactured by using, for example, a known corrugated cardboard corrugator. Further, the one-stage sheet constituting the partition wall 12 can be easily wound into a spiral shape, or processed into various shapes such as a circular cross section, a quadrangle cross section, and a polygonal cross section. By constructing the partition wall 12 that separates the solid fuel 11 by the one-stage sheet that is easy to manufacture and process in this way, it is possible to improve the thrust at the time of combustion while maintaining the ease of manufacturing the grain 10.

In the grain 10 according to the present invention, it is preferable that the partition wall 12 is arranged so that the wavy sheet 14 faces inward. The fact that the wavy sheet 14 faces inward means that the wavy sheet 14 faces the center of the grain 10 among the flat plate-shaped sheet 13 and the wavy sheet 14 constituting the partition wall 12. By arranging the partition wall 12 with the wavy sheet 14 facing inward in this way, the solid fuel 11 can be easily held by the wavy sheet 14. Further, in the case of this arrangement, the outer peripheral surface of the grain 10 becomes the flat plate-shaped sheet 13. As a result, the outer peripheral surface of the grain 10 easily adheres to the inner peripheral surface of the motor case 20 (cylinder) of the rocket engine 100, and the gas generated during combustion efficiently passes through the grain 10. In particular, since the partition wall 12 has a one-stage structure, the outer peripheral surface of the grain 10 can be brought into close contact with the inner peripheral surface of the motor case 20 by the compression recovery force of the structure itself.

In the grain 10 according to the present invention, the partition wall 12 may be configured by spirally winding a one-stage sheet. Thereby, if one single-stage sheet is prepared, the partition wall 12 can be easily formed. In addition, the one-stage sheet can be easily wound in a spiral shape.

The grain 10 according to the present invention may be configured by arranging a partition wall 12 and a cylindrical single-stage sheet over a plurality of layers. That is, a plurality of cylindrical single-stage sheets having different diameters may be prepared and arranged so that the cylinder having a small diameter is housed in the cylinder having a large diameter. Even with such a structure, the partition wall 12 can be easily formed.

The grain 10 according to the present invention may further include a flammable partition wall 16. The partition wall 16 is formed along the radial direction R of the grain 10 in order to partition the storage space of the solid fuel 11 in the circumferential direction C of the grain 10. By providing the partition wall 16 in this way, it is possible to prevent the solid fuel 11 from being displaced. Further, the strength of the grain 10 is also improved by providing the partition wall 16. The partition wall 16 is the embodiment in which the partition wall 12 is formed by spirally winding the above-mentioned single-stage sheet, and the embodiment in which the partition wall 12 is formed by arranging the cylindrical single-stage sheet over a plurality of layers. It can be applied to both. Further, the partition wall 16 may have a simple flat plate shape, or may be composed of a single-stage sheet (single-stage structure) like the partition wall 12. Further, the partition wall 16 may have a truss structure in which one corrugated sheet is sandwiched between two flat sheets and the contact points of the sheets are joined.

In the grain 10 according to the present invention, the solid fuel 11 may be filled between the partition walls 12. The filling means a state in which the solid fuel 11 is arranged substantially without a gap between the wavy sheet 14 of one partition wall 12 and the flat plate sheet 13 of another partition wall 12 facing the wavy sheet 14. For example, by placing the solid fuel 11 on one side of the one-stage sheet and then winding the one-stage sheet while winding the solid fuel 11 to form the partition wall 12, the solid fuel 11 is filled between the partition walls 12. .. Alternatively, the solid fuel 11 may be filled between the partition walls 12 by winding the one-stage sheet to form the partition wall 12 and then pouring the material of the solid fuel 11 between the partition walls 12 to solidify the partition wall 12. Even when the solid fuel 11 is filled between the partition walls 12 in this way, the solid fuel 11 can be efficiently burned because the partition wall 12 itself has a one-stage structure including the void V.

In the grain 10 according to the present invention, the solid fuel 11 may have a rod shape. In addition to the columnar shape, the rod shape includes a square columnar shape, a pentagonal columnar shape, and other polygonal columnar shapes. In this case, when the joint portion between the flat plate-shaped sheet 13 and the corrugated sheet 14 is the valley portion 14a and the portion where the corrugated sheet 14 is separated from the flat plate-shaped sheet 13 is the mountain portion 14b, the solid fuel 11 is used. It is preferably inserted in the valley portion 14a between the two peak portions 14b. The rod-shaped solid fuel 11 does not have to be inserted into all of the valley portions 14a of the one-stage sheet, and there is no problem even if there is a valley portion 14a into which the solid fuel 11 is not inserted. For example, the solid fuel 11 may be placed on the valley portion 14a of the one-stage sheet, and then the one-stage sheet may be wound while the solid fuel 11 is involved to form the partition wall 12. Alternatively, the solid fuel 11 may be inserted between the valley portions 14a of the one-stage sheet after the one-stage sheet is wound to form the partition wall 12. In this way, by inserting the rod-shaped solid fuel 11 between the valleys 14a of the one-stage sheet, the gap V between the solid fuels 11 can be maintained, so that each solid fuel 11 can be efficiently burned. .. Further, even when the rod-shaped solid fuel 11 is inserted, the misalignment of the solid fuel 11 in the grain 10 can be prevented. Further, by forming the solid fuel 11 into a rod shape, the surface area of the solid fuel 11 as a whole is increased, so that the combustion speed of the solid fuel 11 can be increased.

The grain 10 according to the present invention may have a higher oxygen content in the layer of the solid fuel 11 located on the outermost side of the grain 10 than in the layer of the solid fuel 11 located on the innermost side of the grain 10. As the combustion of the grain 10 progresses, the oxidant may be insufficient for the solid fuel 11, but the oxidant deficiency can be compensated for by adjusting the oxygen content of the solid fuel 11 in the outer layer to be high.

In the grain 10 according to the present invention, one or a plurality of combustion spaces S are formed so as to extend along the central axis A direction thereof. When there is only one combustion space S in the grain 10, it is preferable that the combustion space S is formed on the central axis A of the grain 10. On the other hand, when there are a plurality of combustion spaces S of the grain 10, those combustion spaces S need not be necessarily formed on the central axis A as long as they are parallel to the central axis A of the grain 10. Further, in another embodiment, the combustion space S may be formed in a spiral shape in the grain 10.

A second aspect of the present invention relates to a method for producing grains for a hybrid rocket. In the manufacturing method according to the present invention, first, a flammable single-stage sheet is manufactured by joining the flat sheet 13 and the corrugated sheet 14 at the contact point 15 of both (first step). Next, the one-stage sheet is wound while the solid fuel 11 is wound, or the solid fuel 11 is inserted into the layer formed by the one-stage sheet after the one-stage sheet is wound, so that the grain 10 is in the radial direction R. The solid fuel 11 is laminated over a plurality of layers (second step). As a result, a partition wall 12 composed of a single-stage sheet is formed between the layers of the solid fuel 11.

According to the present invention, it is possible to provide a grain for a hybrid rocket in which the thrust at the time of combustion is improved while maintaining the ease of manufacture.

FIG. 1 schematically shows the structure of a hybrid rocket equipped with grains. FIG. 2 shows the cross-sectional structure of the grain according to the first embodiment of the present invention. FIG. 3 shows the cross-sectional structure of the grain partition wall shown in FIG. FIG. 4 shows a perspective view of the partition wall shown in FIG. FIG. 5 is a grain according to the second embodiment, and shows a cross-sectional structure of the grain in which a plurality of rod-shaped solid fuels are inserted into the partition wall shown in FIG. FIG. 6 shows the cross-sectional structure of the grain partition according to the third embodiment of the present invention. FIG. 7 shows a perspective view of a grain partition wall according to a fourth embodiment of the present invention. FIG. 8 shows a cross-sectional structure of a grain partition according to a fifth embodiment of the present invention. FIG. 9 schematically shows an example of a combustion space that can be formed by the partition wall shown in FIG. FIG. 9A shows an example in which two combustion spaces are formed in a straight line, and FIG. 9B shows an example in which two combustion spaces are formed in a double helix. .. FIG. 10 shows a modified example of the grain. FIG. 10A shows an example in which a solid propellant is laminated on the inner peripheral surface of the grain, and FIG. 10B shows an example in which the oxygen content of the solid fuel constituting the grain is changed. There is.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the forms described below, and includes those appropriately modified from the following forms to the extent apparent to those skilled in the art.

FIG. 1 shows the main components of the hybrid rocket 100. As shown in FIG. 1, the hybrid rocket 100 includes a grain 10, a motor case 20, an oxidant tank 30, an injection nozzle 40, and an explosive 50. The grain 10 is generally formed in a cylindrical shape, and a combustion space S is formed inside the grain 10. The motor case 20 is a container for accommodating the grain 10, and is designed to have a strength that can withstand the high-pressure gas generated when the grain 10 is burned. The oxidant tank 30 is a container filled with a liquid oxidant, is connected to the front end side of the motor case 20, and supplies the liquid oxidant into the combustion space S of the grain 10. Examples of liquid oxidants are liquid oxygen and nitrous oxide. The injection nozzle 40 functions as an injection port for gas generated by the combustion of the grain 10, and is connected to the rear end side of the motor case 20. The explosive 50 is arranged in the combustion space S of the grain 10.

When launching the hybrid rocket 100, the liquid oxidant in the oxidant tank 30 is supplied to the combustion space S of the grain 10 and the explosive 50 is ignited. As a result, the grain 10 (combustible material) starts combustion with the explosive 50 as the first heat source and the oxygen contained in the liquid oxidant as the combustible material. When the grain 10 burns, gas is generated in the motor case 20, and when the pressure in the motor case 20 becomes a predetermined value or more, the combustion gas is injected from the injection nozzle 40. This gives thrust to the hybrid rocket 100. The combustion of the grain 10 proceeds from the center toward the outer circumference so that the combustion space S gradually expands. When all the grain 10 burns or the liquid oxidant in the oxidant tank 30 runs out, the combustion of the grain 10 ends. The combustion of the grain 10 can also be stopped by stopping the supply of the liquid oxidant from the oxidant tank 30 to the grain 10.

The present invention mainly relates to the grain 10 contained in the hybrid rocket 100. However, it is also possible to extend the scope of the present invention to the hybrid rocket 100 equipped with the grain 10. In that case, known motor cases 20, an oxidant tank 30, a liquid oxidant, an injection nozzle 40, and an explosive 50 can be used. Hereinafter, the grain 10 will be described in detail.

2 to 4 show the grain 10 according to the first embodiment of the present invention. As shown in FIG. 2, the grain 10 includes a solid fuel 11 and a partition wall 12. As shown in FIGS. 2 to 4, the grain 10 is formed in a substantially columnar shape, and a combustion space S is provided at the center thereof. Further, in FIG. 4, the central axis of the columnar grain 10 is indicated by reference numeral A, the radial direction is indicated by reference numeral R, and the circumferential direction is indicated by reference numeral C.

The solid fuel 11 is laminated over a plurality of layers when viewed in the radial direction R of the grain 10. A partition wall 12 is provided to separate each layer of the solid fuel 11 in the radial direction R. The grain 10 according to the present invention basically has a multi-layer structure of the solid fuel 11 separated by such a partition wall 12.

As the material of the solid fuel 11, for example, a hydrocarbon-based polymer generally used in a hybrid rocket or the like may be adopted. For example, as the solid fuel 11, it is preferable to use a polyolefin resin such as polyethylene, polypropylene, and an ethylene / propylene copolymer. In addition, examples of the solid fuel 11 include polybutadiene resins such as terminal hydroxyl group polybutadiene and terminal carboxyl group polybutadiene; polyester resins such as polyester type polyurethane and polyether type polyurethane; polyester resins such as polylactic acid and polyethylene terephthalate; acrylonitrile. Polyacrylonitrile-based resins such as homopolymers and acrylonitrile copolymers; polyvinyl chloride resins; poly (meth) acrylic acid ester-based resins such as polymethylmethacrylate; polyisobutylene; epoxy resins; paraffin and the like can also be used. Further, a combination of fat and oil and an amino acid-based gelling agent, or a combination of ethanol and calcium acetate can also be used.

The thickness of each layer of the solid fuel 11 can be appropriately adjusted, but it is preferably thicker than the flat plate-shaped sheet 13 and the wavy sheet 14 described later. For example, the thickness of each layer of the solid fuel 11 is preferably 0.1 mm or more, and may be 0.25 mm or more, 0.5 mm or more, or 1 mm or more. The upper limit of the thickness of each layer of the solid fuel 11 is preferably 200 mm or less, and may be 150 mm or less, 20 mm or less, 15 mm or less, 5 mm or less, or 3 mm or less. Specifically, the preferable thickness differs depending on the form of the solid fuel 11. For example, when the solid fuel 11 is in the form of a sheet, the thickness of each layer is preferably 0.1 mm or more, more preferably 0.25 mm or more. Further, since it is easy to wind together with the one-stage sheet, the upper limit of the thickness of each layer of the solid fuel 11 is preferably 5 mm or less, and more preferably 3 mm or less. When the solid fuel 11 has a rod shape, the thickness of each layer is preferably 0.5 mm or more, and more preferably 1 mm or more, because it is not necessary to use a large number of rod-shaped fuels that are too thin. The upper limit of the thickness of each layer of the solid fuel 11 is preferably 20 mm or less, more preferably 15 mm or less. On the other hand, when the material of the solid fuel 11 having fluidity is poured between the partition walls 12 and then solidified for use, the thickness of each layer is preferably 0.1 mm or more, more preferably 0.25 mm or more. The upper limit of the thickness of each layer of the solid fuel 11 is preferably 200 mm or less, more preferably 150 mm or less.

The structure of the partition wall 12 is shown in detail in FIG. The partition wall 12 is composed of a single-stage sheet. This one-stage sheet has a structure in which a flat plate-shaped sheet 13 and a wavy sheet 14 are joined at a contact point 15 of both. At the contact point 15, the flat plate-shaped sheet 13 and the wavy sheet 14 may be joined by applying an adhesive, or the flat plate-shaped sheet 13 and the wavy sheet 14 may be locally heated by heat-sealing to melt. It may be joined by letting them join.

In the one-stage sheet constituting the partition wall 12, the flat plate-shaped sheet 13 and the wavy sheet 14 are joined at the contact point 15, but are partially separated from each other. Therefore, a gap V is formed between the flat plate-shaped sheet 13 and the wavy sheet 14. Further, the wavy sheet 14 repeats undulations periodically, and the flat plate-shaped sheet 13 is attached to one side thereof. Therefore, in the one-stage sheet, a valley portion 14a is formed at the contact point 15 (joint portion) between the flat plate-shaped sheet 13 and the corrugated sheet 14, and a mountain portion 14b is formed at the portion where the flat plate-shaped sheet 13 and the corrugated sheet 14 are peeled off. It will be formed.

Further, in FIG. 3, the thickness of the flat plate _- shaped sheet 13 is indicated by reference numeral T1, and the thickness of the corrugated sheet ₁₄ is indicated by reference numeral T2. The thickness T ₁ of the flat sheet 13 and the thickness T ₂ of the wavy sheet 14 are, for example, 0.05 mm or more, respectively, considering that the one-stage sheet is provided with sufficient strength to maintain a gap between the solid fuels 11. , 0.07 mm or more, 0.1 mm or more, 0.15 mm or more, 0.2 mm or more, or 0.25 mm or more is preferable. On the other hand, if the sheets 13 and 14 are too thick, it becomes difficult to process and manufacture the one-stage sheet. Therefore, the thicknesses T ₁ and T ₂ of the sheets 13 and 14 are preferably less than 1 mm, respectively, specifically. It is preferably 0.9 mm or less, 0.8 mm or less, 0.7 mm or less, 0.6 mm or less, or 0.5 mm or less. The thicknesses of the flat plate-shaped sheet 13 and the corrugated sheet 14 may be the same or different from each other.

Further, in FIG. 3, the distance between the contact point 15 (joint portion) between the corrugated sheet 14 and the flat plate sheet 13 is indicated by reference numeral P. Since the wavy sheet 14 is undulating at a constant cycle, the interval P is also basically constant. The interval P is not particularly limited and may be appropriately adjusted according to the size of the grain 10 and the hybrid rocket 100 on which the grain 10 is mounted. For example, the interval P can be 1 mm or more, 2 mm or more, or 3 mm or more, and the upper limit thereof may be 10 mm or less, 8 mm or less, or 6 mm or less.

Further, in FIG. 3, the height of the gap V formed between the wavy sheet 14 and the flat plate sheet 13 is indicated by the reference numeral H. The height H of the gap V is also not particularly limited, and may be appropriately adjusted according to the size of the grain 10 and the hybrid rocket 100 on which the grain 10 is mounted. For example, the height H of the gap V can be 0.3 mm or more, 0.5 mm or more, or 1 mm or more, and the upper limit thereof may be 10 mm, 5 mm or less, or 3 mm or less.

The wavy sheet 14 and the flat plate sheet 13 constituting the one-stage sheet are each made of a flammable material. As the material of each of the sheets 13 and 14, for example, flammable paper or thermoplastic resin can be selected. As a raw material for paper, wood such as hardwood and coniferous wood, and vegetable fibers such as used paper, hemp, mulberry, mitsumata, and bamboo can be used. The thermoplastic resin forming the sheets 13 and 14 includes a polyolefin resin, a polybutadiene resin, a polyurethane resin, a polyester resin, a polyacrylonitrile resin, and a polyvinyl chloride resin, as in the solid fuel 11 described above. , Poly (meth) acrylic acid ester-based resin, polyisobutylene, epoxy resin, and hydrocarbon-based polymers such as paraffin may be used. The corrugated sheet 14 and the flat plate sheet 13 may be made of the same kind of material or may be made of different materials. Further, although the one-stage sheet constituting the partition wall 12 and the solid fuel 11 can be formed of the same material, they may be formed of different materials.

Such a one-stage sheet can be easily processed and manufactured by using a known corrugated cardboard corrugator (for example, Japanese Patent Application Laid-Open No. 58-153631). For example, when both the flat plate-shaped sheet 13 and the corrugated sheet 14 are made of thermoplastic resin, the corrugated sheet 14 is obtained by thermoforming the heated corrugated roll with a resin original plate in a wavy shape, and the heated corrugated roll is formed. A flat sheet 13 and a corrugated sheet 14 may be introduced between the roll and the flat press roll, and both sheets 13 and 14 may be thermocompression bonded. This makes it possible to industrially produce a one-stage sheet in which the flat sheet 13 and the corrugated sheet 14 are joined without using an adhesive. However, it is also possible to adopt a method of adhering the flat sheet 13 and the corrugated sheet 14 using an adhesive.

In the first embodiment shown in FIGS. 2 to 4, the spiral partition wall 12 is formed by winding the one-stage sheet. The partition wall 12 is arranged so that the corrugated sheet 14 faces inward and the flat plate sheet 13 faces outward. The solid fuel 11 is filled between the spiral partition walls 12. As a result, a plurality of layers of the solid fuel 11 are formed in the radial direction of the grain 10 toward R. In the present embodiment, in each layer, the solid fuel 11 is in close contact with the flat sheet 13 of one partition wall 12 and the wavy sheet 14 of the next partition wall 12. However, since the gap between the layers of the solid fuel 11 can be maintained by the compression recovery force in the height direction of the wavy sheet 14 of the one-stage sheet, the combustion efficiency of the solid fuel 11 can be improved and a large thrust can be obtained at the time of combustion. ..

In the embodiment shown in FIG. 2, the solid fuel 11 has three or four layers, but the number of layers of the solid fuel 11 depends on the size of the grain 10 and the hybrid rocket 100 on which the solid fuel 11 is mounted. It can be adjusted as appropriate. For example, the number of layers of the solid fuel 11 is not particularly limited, but for example, three or more layers are preferable.

The grain 10 according to the present embodiment can be manufactured, for example, by placing the solid fuel 11 on the one-stage sheet before winding and then winding the solid fuel 11 in a spiral shape while winding the solid fuel 11. can. As another method, after winding the one-stage sheet in a spiral shape, the material of the solid fuel 11 having fluidity is poured between the partition walls 12 formed by the one-stage sheet, and then the material of the solid fuel 11 is solidified. Can also produce grain 10.

Further, as shown in the perspective view of FIG. 4, in the grain 10 according to the present embodiment, the contact point 15 (joint portion) between the flat plate-shaped sheet 13 of the one-stage sheet forming the partition wall 12 and the corrugated sheet 14 is a grain. It is formed in a straight line so as to extend parallel to the central axis A of 10. Making the contact point 15 parallel to the central axis A of the grain 10 in this way is the easiest method for processing the one-stage sheet into a spiral shape due to the structure of the one-stage sheet.

Subsequently, another embodiment of the grain 10 according to the present invention will be described. The other embodiment will be described focusing on the differences from the first embodiment described above. In another embodiment, the same elements as those in the first embodiment described above are designated by the same reference numerals, and the details thereof will be omitted.

FIG. 5 shows the cross-sectional structure of the grain 10 according to the second embodiment of the present invention. The grain 10 according to the second embodiment has the same structure of the partition wall 12 as that of the first embodiment, but the layer structure of the solid fuel 11 is different from that of the first embodiment. That is, as shown in FIG. 2, in the second embodiment, a plurality of rod-shaped (particularly columnar) solid fuels 11 are adopted. By inserting and arranging such rod-shaped solid fuels 11 between the partition walls 12, a layer of the solid fuels 11 is formed.

More specifically, the rod-shaped solid fuel 11 is arranged in the valley portion 14a between the two peak portions 14b in the one-stage sheet forming the partition wall 12 (see FIG. 3). By inserting the solid fuel 11 into the valley portion 14a of the one-stage sheet in this way, it is possible to prevent the position of the solid fuel 11 from being displaced after the grain 10 is completed.

In the embodiment shown in FIG. 5, the rod-shaped solid fuel 11 is arranged in almost all the valleys 14a of the one-stage sheet, but it is not always necessary to do so. For example, the valley portion 14a in which the solid fuel 11 is arranged and the valley portion 14a in which the solid fuel 11 is not arranged may be alternately arranged. It is also possible to change the ratio of the valley portion 14a in which the solid fuel 11 is arranged for each layer. For example, in the layer near the center of the grain 10, the proportion of the valley portion 14a in which the solid fuel 11 is arranged can be increased, and in the layer near the outer periphery of the grain 10, the proportion of the valley portion 14a in which the solid fuel 11 is arranged can be decreased. ..

FIG. 6 shows the cross-sectional structure of the partition wall 12 of the grain 10 according to the third embodiment of the present invention. Although the solid fuel 11 is not shown in FIG. 6, in the third embodiment, the method of filling the solid fuel 11 between the partition walls 12 shown in FIG. 2 and the partition wall shown in FIG. 5 are shown. Either of the methods of inserting a plurality of rod-shaped solid fuels 11 between the 12 may be adopted.

As shown in FIG. 6, in the third embodiment, instead of winding the one-stage sheet in a spiral shape, first, a plurality of cylinders composed of the one-stage sheet are prepared. Multiple cylinders have different diameters, and a small diameter cylinder is placed inside a large diameter cylinder. At this time, a plurality of cylinders composed of one-stage sheets are arranged concentrically. In this way, the partition wall 12 over a plurality of layers can be formed by the plurality of tubular single-stage sheets.

Further, in the third embodiment, a flammable partition wall 16 formed along the radial direction R is further provided in order to partition the storage space for the solid fuel 11 in the circumferential direction C of the grain 10. By providing such a partition wall 16, the distance between the cylindrical partition walls 12 can be maintained. In the example shown in FIG. 6, each partition wall 16 is formed in a simple flat plate shape. However, the partition wall 16 can also be formed by a single-stage sheet like the partition wall 12. As the flammable material of the partition wall 16, for example, the same material as the flat plate-shaped sheet 13 or the corrugated sheet 14 forming the one-stage sheet may be adopted.

In the example shown in FIG. 6, four layers for storing the solid fuel 11 are formed by five cylindrical single-stage sheets (partition walls 12), and the partition walls 16 arranged in each layer are arranged in a straight line. They are lined up. However, the arrangement of the partition wall 16 of each layer is not limited to this, and for example, the partition wall 16 may be arranged so as to be shifted to the left or right for each layer. Further, in the example shown in FIG. 6, the number of partition walls 16 arranged in each layer is the same (specifically, 12), but the number of partition walls 16 in each layer may be different. For example, in order to unify the size of the storage space of the solid fuel 11, it is possible to reduce the number of partition walls 16 in the inner layer and increase the number of partition walls 16 in the outer layer.

FIG. 7 shows a perspective view of the partition wall 12 of the grain 10 according to the fourth embodiment of the present invention. Although the solid fuel 11 is not shown in FIG. 7, in the fourth embodiment, the method of filling the solid fuel 11 between the partition walls 12 shown in FIG. 2 and the partition wall shown in FIG. 5 are shown. Either of the methods of inserting a plurality of rod-shaped solid fuels 11 between the 12 can be adopted.

Although it is easy to understand by comparing FIGS. 7 and 4, in the fourth embodiment shown in FIG. 7, unlike the first embodiment shown in FIG. 4, the flat plate-shaped sheet 13 and the wavy one-stage sheet forming the partition wall 12 are wavy. The contact point 15 (joint portion) of the sheet 14 is tilted at a predetermined angle θ with respect to the central axis A of the grain 10. The angle θ at which the contact point 15 is tilted with respect to the central axis A is preferably 5 to 35 degrees. By inclining the contact point 15 in this way, the gap V between the flat plate sheet 13 and the corrugated sheet 14 is also inclined in parallel with the contact point 15. As a result, a swirling flow of combustion gas can be generated in the combustion space S when the solid fuel 11 is burned, and the solid fuel 11 can be uniformly burned. Further, by swirling the combustion gas, the injection direction of the combustion gas is stabilized and the obtained thrust is also stabilized.

Further, in the fourth embodiment shown in FIG. 7, when a plurality of rod-shaped solid fuels 11 are inserted between the partition walls 12, the rod-shaped solid fuel 11 is in contact with the flat plate-shaped sheet 13 and the wavy sheet 14. It is preferable to arrange it along the point 15. That is, the rod-shaped solid fuel 11 is also inserted between the partition walls 12 together with the contact point 15 in a state of being inclined at a predetermined angle θ with respect to the central axis A of the grain 10.

FIG. 8 shows the cross-sectional structure of the partition wall 12 of the grain 10 according to the fifth embodiment of the present invention. Although the illustration of the solid fuel 11 is omitted in FIG. 8, in the fifth embodiment, the method of filling the solid fuel 11 between the partition walls 12 shown in FIG. 2 and the partition wall 12 shown in FIG. 5 Either of the methods of inserting a plurality of rod-shaped solid fuels 11 between them can be adopted.

As shown in FIG. 8, the partition wall 12 in the fifth embodiment is designed to form a first combustion space S1 and a second combustion space S2 in a substantially cylindrical grain 10. That is, in the example shown in FIG. 8, the partition wall 12 is composed of the first to fifth single-stage sheets 12 (a) to 12 (e). The first single-stage sheet 12 (a) is spirally wound so as to form the outer circumference of the grain 10. The second single-stage sheet 12 (b) is arranged inside the first single-stage sheet 12 (a) and is spirally wound so as to form the first combustion space S1. The third single-stage sheet 12 (c) is arranged inside the first single-stage sheet 12 (a) and is spirally wound so as to form the second combustion space S2. In the illustrated example, the first combustion space S1 and the second combustion space S2 have substantially the same diameter, but the diameters of these spaces S1 and S2 can be different. Further, the fourth and fifth single-stage sheets 12 (d) and 12 (e) are arranged inside the first single-stage sheet 12 (a), and the first single-stage sheet 12 (a) and the second and second single-stage sheets 12 (a) are arranged. The shape is bent or curved at an appropriate portion so as to fill the gap between the single-stage sheets 12 (b) and 12 (c) of 3. In this way, it is also possible to form the partition wall 12 by using the plurality of single-stage sheets 12 (a) to 12 (e).

Up to this point, the grain 10 in which the combustion efficiency of the solid fuel 11 has been improved by forming the void V between the layers of the solid fuel 11 by using the partition wall 12 having a one-stage structure has been described. Depending on the method, a grain having high combustion efficiency can be obtained even though the void V is also filled with the solid fuel. Specifically, for example, the combination of the one-stage sheet wound material or the cylindrical object shown in FIGS. 3, 6, 7 and 8 is impregnated with the material of the fluid solid fuel 11 and then the material of the solid fuel 11. The grain 10 is produced by solidifying. In this case, the solid fuel is also filled in the region corresponding to the void V shown in FIG.

Examples of the fluid solid fuel include epoxy resin, paraffin typified by wax, a combination of fat and oil with an amino acid gelling agent, a combination of ethanol and calcium acetate, and the like among the above-mentioned solid fuel 11. .. Of these, the combinations of paraffin represented by wax, the combination of fats and oils with an amino acid-based gelling agent, and the combination of ethanol and calcium acetate are all lower than those described above as materials for the wavy sheet 14 and the flat sheet 13. Has a melting point. For example, when a sheet made of a thermoplastic resin is used as the one-stage sheet and a flammable material having a melting point lower than that of the one-stage sheet is used as the solid fuel 11, the one-stage sheet melts and has holes when the grain 10 is burned. Combustible gas, that is, the liquefied solid fuel 11 is ejected into the combustion space to promote combustion and increase the retreat speed. Further, the combination of the epoxy resin, the fat and oil and the amino acid gelling agent, and the combination of ethanol and calcium acetate all have a higher oxygen content than those described above as the materials of the wavy sheet 14 and the flat plate sheet 13. For example, when the oxygen content in the solid fuel 11 is higher than the oxygen content in the one-stage sheet, the oxygen supply amount in the grain 11 increases as the combustion progresses, which is preferable because the recession rate further increases. .. The oxygen content will be described later.

When the material of the solid fuel 11 having fluidity is impregnated between the partition walls 12 and then solidified for use, the thickness of the solid fuel 11 layer is preferably 0.1 mm or more, preferably 0.25 mm or more. Is more preferable. The upper limit of the thickness of each layer of the solid fuel 11 is preferably 200 mm or less, more preferably 150 mm or less.

FIG. 9 schematically shows a grain 10 provided with two combustion spaces S1 and S2. In the example shown in FIG. 9A, the two combustion spaces S1 and S2 extend linearly in parallel with the central axis of the grain 10, respectively. On the other hand, in the example shown in FIG. 9B, the two combustion spaces S1 and S2 extend in a spiral shape, respectively, and a double helix is formed by these combustion spaces S1 and S2. In FIG. 9B, in addition to the positional relationship between the combustion spaces S1 and S2 on the top surface and the bottom surface of the grain 10, the positional relationship between the combustion spaces S1 and S2 on the two cut surfaces between them is schematically shown. Represents. As described above, the combustion spaces S1 and S2 of the grain 10 are not limited to a linear shape, but may be a spiral shape. By making the combustion spaces S1 and S2 of the grain 10 spiral, a swirling flow of combustion gas can be generated.

FIG. 10 shows a modified example of the grain 10 according to the present invention. The modification shown in FIG. 10 can be applied to any of the first to fifth embodiments described above. 10 (a) and 10 (b) show the cross-sectional structure of the grain 10.

In the modified example shown in FIG. 10A, the solid propellant 60 is further laminated on the inner peripheral surface of the above-mentioned grain 10 (including the solid fuel 11 and the partition wall 12). As described above, the grain 10 burns with a liquid oxidant as a combustion support, while the solid propellant 60 is a solid fuel and a solid oxidant bonded with a binder and burned by itself. do. Known solid fuels, solid oxidants, and binders constituting the solid propellant 60 may be used.

By laminating the solid propellant 60 on the inner peripheral surface of the substantially cylindrical grain 10 in this way, the rocket can obtain thrust in two stages. That is, in the first stage, thrust is applied to the rocket by burning the solid propellant 60 alone. Once the solid propellant 60 has finished burning, the rocket once loses thrust. Since the grain 10 does not burn by itself, the fire does not spread from the solid propellant 60 to the grain 10. After that, in the second stage, the liquid fuel is supplied from the oxidant tank 30 (see FIG. 1) to the combustion space S of the grain 10 and ignited again in the combustion space S, so that the grain 10 starts combustion. This allows the rocket to be thrust again. Therefore, for example, the solid propellant 60 is burned at the time of launch from the ground, and the liquid oxidizer is supplied at the time of returning from outer space or the atmosphere to burn the grain 10. You can switch.

In the modification shown in FIG. 10B, in the above-mentioned grain 10, the oxygen content in each layer of the solid fuel 11 is gradually increased from the center of the grain 10 toward the outer periphery. In the example of FIG. 10B, the grain 10 is divided into a first layer 10 (a), a second layer 10 (b), a third layer 10 (c), and a fourth layer 10 (d) in order from the center of the grain 10. ing. In this case, the oxygen content of each layer increases in the order of the first layer 10 (a), the second layer 10 (b), the third layer 10 (c), and the fourth layer 10 (d). In the hybrid rocket, a liquid oxidant is supplied to the combustion space S at the center of the grain 10 to burn the solid fuel 11 constituting the grain 10, but the supply amount of the liquid oxidant decreases toward the outer periphery of the grain 10. do. Therefore, the shortage of the liquid oxidant can be compensated by increasing the oxygen content toward the outer periphery of the grain 10.

The "oxygen content" referred to here is the content of oxygen atoms contained in the substance constituting the fuel expressed in mass%. Examples of the substance containing an oxygen atom include diglycidyl azide polymer, polyethylene glycol, polymethylmethacrylate, polyethylene terephthalate, epoxy resin, cellulose, ethanol, oil and fat and the like. The oxygen content can be determined by an elemental analysis method. Examples of the elemental analysis method include a method of quantifying the generated nitric oxide by burning a sample under anoxic conditions in a helium carrier at 1050 ° C.

As described above, in the present specification, in order to express the content of the present invention, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the above embodiment, and includes modifications and improvements which are obvious to those skilled in the art based on the matters described in the present specification.

10 ... Grain 11 ... Solid fuel 12 ... Bulk partition 13 ... Flat sheet 14 ... Wavy sheet 14a ... Tanibe 14b ... Yamabe 15 ... Contact point 16 ... Partition wall 20 ... Motor case 30 ... Oxidizing agent tank 40 ... Injection nozzle 50 ... Explosive 100 ... Hybrid rocket S ... Combustion space S1 ... First combustion space S2 ... Second combustion space V ... Void

Claims (10)

A grain for hybrid rockets
A solid fuel laminated over a plurality of layers in the radial direction in the cross-sectional circle of the grain,
Includes flammable bulkheads separating the layers of the solid fuel,
The partition wall is a grain composed of a single-stage sheet in which a flat sheet and a corrugated sheet are joined at a contact point between the two. The grain according to claim 1, wherein the partition wall is arranged so that the wavy sheet faces inward. The grain according to claim 1, wherein the partition wall is formed by winding the one-stage sheet. The grain according to claim 1, wherein the partition wall is formed by arranging the cylindrical single-stage sheet over a plurality of layers. The grain according to claim 1, further comprising a flammable partition wall formed along the radial direction to partition the storage space for the solid fuel in the circumferential direction of the grain. The grain according to claim 1, wherein the solid fuel is filled between the partition walls. The solid fuel is rod-shaped and has a rod shape.
When the joint portion between the flat plate-shaped sheet and the wavy sheet is a valley portion and the portion where the wavy sheet is separated from the flat plate-shaped sheet is a mountain portion in the one-stage sheet, the solid fuel has two mountain portions. The grain according to claim 1, which is inserted in the valley between the two. The grain according to claim 1, wherein the layer of the solid fuel located on the outermost side of the grain has a higher oxygen content than the layer of the solid fuel located on the innermost side of the grain. The grain according to claim 1, wherein the grain has one or more combustion spaces formed so as to extend along the central axis direction thereof. A method for manufacturing grains for hybrid rockets.
The process of manufacturing a flammable single-stage sheet in which a flat sheet and a corrugated sheet are joined at the contact point between the two,
By winding the one-stage sheet while entraining the solid fuel, or by inserting the solid fuel into the layer formed by the one-stage sheet after winding the one-stage sheet, a plurality of the solid fuels are wound in the radial direction of the grain. A manufacturing method that includes a step of laminating solid fuel over layers.

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