Reuse thermal protection device and method for bottom of first sub-stage of rocket

Abstract

The invention provides a reusable thermal protection device and method for the bottom of a first sub-stage of a rocket. The reuse thermal protection device used for the bottom of the first sub-stage of the rocket comprises a heat protection plate and a heat insulation plate, the heat protection plate and the heat insulation plate are fixed to each other, a heat insulation cavity is formed between the heat insulation plate and the heat protection plate after being fixed, when the rocket flies, the heat protection plate absorbs and insulates heat, and after the rocket is recycled, the heat insulation cavity is formed between the heat insulation plate and the heat protection plate. After the heat-proof plate is replaced, the next rocket launching is continued; the heatproof plate comprises a base plate, a coating and a thermal radiation heat insulation layer. The coating is arranged on the first surface of the base plate and used for absorbing heat when the rocket flies; the heat radiation and heat insulation layer is arranged on the second surface of the base plate and used for reducing the heat radiation exchange amount between the heat protection plate and the heat insulation plate when the rocket flies; the first surface and the second surface are the surfaces, opposite to each other, of the heatproof plate. And the heat-proof plate can be replaced and repeatedly used for rocket launching, so that the purpose of reducing the cost is achieved.

Description

Technical Field

[0001] This invention belongs to the field of rocket technology, and in particular relates to a reusable thermal protection device and method for the bottom of a rocket first stage. Background Technology

[0002] In recent decades, launch vehicle design and improvements have primarily focused on requirements such as high efficiency and high reliability. The adoption of reusable designs has significantly reduced space launch costs and has guided the technological development direction of the launch vehicle field. Countries and related companies have recognized that simply modifying existing expendable rockets using existing technological approaches is no longer sufficient for future needs. Reusable design has become a key technological feature of next-generation launch vehicles.

[0003] Currently, reusable rockets are partially reusable, meaning that after the first stage returns to Earth, it is inspected and then launched again. To increase payload capacity, the first stage often uses multiple engines in parallel. When multiple engines operate in parallel, the exhaust gases from the main engine and boosters shear and mix with each other, forming a complex flow field structure. This interference leads to uneven heat distribution in the bottom region, creating localized high-temperature areas. During the first stage's reentry, the interaction between the engine exhaust and the incoming airflow results in a significantly higher heat flux at the bottom of the reentry phase compared to the ascent phase.

[0004] Currently, the heat shielding method for the bottom of the first stage of rockets is based on the ablation principle. When the jet impacts and radiates onto the surface of the heat shield, it generates high-temperature ablation, which removes a large amount of heat. Therefore, selecting an appropriate heat shield thickness can ensure that the temperature on the back of the heat shield remains below 110°C. However, such heat shields are expensive. For expendable rockets, the heat shield will burn up during reentry. But for reusable rockets, if such expendable heat shields are still used, they need to be completely removed and replaced with new heat shields after the first stage returns, increasing the reuse cost of reusable rockets. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a reusable thermal protection device and method for the bottom of the first stage of a rocket, which at least partially solves the problem of high cost in the prior art.

[0006] In a first aspect, the present disclosure provides a reusable thermal protection device for the bottom of the first stage of a rocket, including a heat shield and a heat insulation plate. The heat shield and the heat insulation plate are fixed to each other, and a heat insulation cavity is formed between the fixed heat insulation plate and the heat shield. When the rocket is in flight, the heat shield absorbs and isolates heat. When the rocket is recovered, the heat shield is replaced and can be used for the next rocket launch. The heat shield includes a substrate, a coating, and a heat radiation insulation layer; the coating is disposed on a first surface of the substrate for absorbing heat during rocket flight; the heat radiation insulation layer is disposed on a second surface of the substrate for reducing the amount of heat radiation exchange between the heat shield and the insulation plate during rocket flight; the first surface and the second surface are surfaces of the heat shield that are opposite to each other.

[0007] Optionally, the surface of the heat insulation plate facing the heat protection plate is covered with a heat radiation insulation layer.

[0008] Optionally, the insulation board is a glass fiber composite board.

[0009] Optionally, the side of the heat insulation plate facing the heat protection plate is provided with a groove, and the groove area is provided with air holes that penetrate through both sides of the thickness direction of the heat insulation plate and communicate with the heat insulation cavity.

[0010] Optionally, the diameter of the pores is 1.5~2.5mm, multiple pore arrays are arranged, the spacing between adjacent pores is 15mm, and the porosity of the heat insulation plate in its groove area is 0.73%.

[0011] Optionally, a protruding heat insulation pad is provided on the surface of the heat insulation plate facing the heat protection plate, and an installation component is provided inside the heat insulation pad for installing the heat protection plate.

[0012] Optionally, it also includes a structural crossbeam for mounting the protective device onto the rocket.

[0013] Optionally, the coating is an ablation-type heat-resistant coating, the substrate is a composite phenolic substrate, and the heat radiation insulation layer is stainless steel foil.

[0014] Optionally, the thickness of the composite phenolic substrate is 3~5mm, the thickness of the ablation-type heat-resistant coating is 3~6mm, and the thickness of the stainless steel foil is 0.05mm.

[0015] In a second aspect, the present disclosure also provides a method for reusable thermal protection at the bottom of a rocket first stage, wherein the reusable thermal protection device described in any of the first aspects is installed at the bottom of the rocket first stage. During the entire flight of the first stage of the rocket, the first stage of heat protection is provided by the substrate and coating. After absorbing the heat flow, the coating begins to ablate and decompose, thereby reducing the heat flow transferred to the substrate. After the substrate is heated, the heat radiation is transferred to the surrounding structure. The heat radiation insulation layer provided on the second surface of the substrate reduces the amount of heat radiation exchange. After the first stage of the rocket is recovered, the heat shield is removed and replaced with a new one for the next flight launch mission.

[0016] The present invention provides a reusable thermal protection device and method for the bottom of the first stage of a rocket. The reusable thermal protection device for the bottom of the first stage of a rocket has a heat shield plate installed on a heat insulation plate. After the rocket is recovered, the heat shield plate can be disassembled and replaced for the next rocket launch, thereby achieving the purpose of reducing costs. Attached Figure Description

[0017] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0018] Figure 1 A schematic diagram of the structure of a reusable thermal protection device for the bottom of a rocket first stage provided in an embodiment of this disclosure; Among them, 1-coating; 2-substrate; 3-stainless steel foil; 4-insulation board; 5-structural beam; 6-pore; 7-groove; 8-insulation pad. Detailed Implementation

[0019] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0020] It should be understood that the following specific examples illustrate the implementation of this disclosure, and those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0021] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0022] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The illustrations only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0023] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0024] like Figure 1 As shown, this embodiment discloses a reusable thermal protection device for the bottom of the first stage of a rocket, including a heat shield and a heat insulation plate 4. The heat shield and the heat insulation plate 4 are fixed together, and a heat insulation cavity is formed between the fixed heat insulation plate and the heat shield. When the rocket is in flight, the heat shield absorbs and isolates heat. After the rocket is recovered, the heat shield is replaced and can be used for the next rocket launch. The heat insulation cavity formed between the heat shield and the heat shield is connected to the atmospheric environment. The gas in the heat insulation cavity isolates the heat, thereby reducing the heat transferred to the heat shield and preventing the high temperature outside the rocket from damaging the heat shield.

[0025] The heat shield includes a substrate 2, a coating 1, and a heat radiation insulation layer. The coating 1 is disposed on a first surface of the substrate 2 to absorb heat during rocket flight. The heat radiation insulation layer is disposed on a second surface of the substrate 2 to reduce the amount of heat radiation exchange between the heat shield and the insulation plate 4 during rocket flight. The first and second surfaces are arranged opposite to each other; the first and second surfaces are the surfaces of the heat shield that are opposite to each other.

[0026] The surface of the heat insulation board 4 facing the heat shield is covered with a heat radiation insulation layer. The heat insulation board 4 is a fiberglass composite board. A groove 7 is provided on the side of the heat insulation board facing the heat shield, and air holes 6 are formed in this groove 7, penetrating both sides of the heat insulation board in the thickness direction and communicating with the heat insulation cavity. During rocket flight, the groove 7 is filled with air, which insulates against heat, and the air holes 6 are used to reduce the pressure difference between the inside and outside of the groove 7. The diameter of the air holes 6 is 1.5~2.5mm, and multiple air holes 6 are arranged in an array, with an adjacent air hole spacing of 15mm. The porosity of the heat insulation board 4 in the groove 7 area is 0.73%.

[0027] A protruding heat insulation pad 8 is provided on the surface of the heat insulation plate 4 facing the heat protection plate. The heat insulation pad 8, the heat protection plate and the heat insulation plate 4 form a heat insulation cavity in the groove 7. An installation component is provided in the heat insulation pad 8, and the installation component is used to install the heat protection plate.

[0028] The device also includes a structural beam 5, which is used to mount the protective device onto the rocket. The heat shield 4 is bolted to the structural beam 5.

[0029] In a specific application, the heat insulation plate 4 is located on top of the heat protection plate. The heat insulation plate 4 has a flat structure, and the surface facing the heat protection plate has protruding heat insulation pads 8. The heat insulation pads 8 and the heat insulation plate 4 are manufactured as a single unit. The heat insulation pads 8 contain bolt mounting blocks for bolt fastening to the heat protection plate. The height of the heat insulation pads 8 is 8~12mm. Stainless steel foil 3 is adhered to the opposing surfaces of the heat insulation plate 4 and the heat protection plate.

[0030] Coating 1 is an ablation-type heat-resistant coating, substrate 2 is a composite phenolic substrate, and the heat radiation insulation layer is stainless steel foil 3. The thickness of the composite phenolic substrate is 3-5 mm, and the thickness can be 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc. The thickness of the ablation-type heat-resistant coating is 3-6 mm, and the thickness can be 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc. The stainless steel foil 3 is 0.05 mm thick. The stainless steel foil 3 is bonded to the back side of the composite phenolic substrate (i.e., the second surface mentioned above) using high-temperature adhesive. In a specific embodiment, the thickness of the composite phenolic substrate is 5 mm, the thickness of the ablation-type heat-resistant coating is 3 mm, and the thickness of the stainless steel foil 3 is 0.05 mm.

[0031] In one specific application, an ablation-type heat-resistant coating is sprayed onto the substrate 2, and stainless steel foil 3 is adhered to the inner surface (i.e., the second surface of the substrate facing the heat insulation plate). The stainless steel foil 3 is used to reduce heat radiation exchange. The heat insulation plate 4 is made of a material with low thermal conductivity and is bolted to the substrate 2. The heat insulation plate 4 is also bolted to the structural beam 5. Inlet and outlet vents 6 are provided on the heat insulation plate 4 to reduce the internal and external pressure difference. Stainless steel foil 3 is also adhered to the surface of the heat insulation plate 4 adjacent to the heat insulation plate to reduce the amount of heat radiation exchange.

[0032] This embodiment also discloses a reusable thermal protection method for the bottom of the first stage of a rocket, wherein the reusable thermal protection device disclosed in this embodiment is installed at the bottom of the first stage of the rocket. During the entire flight of the first stage of the rocket, the first stage of heat protection is provided by the substrate 2 and the coating 1. After absorbing the heat flow, the coating 1 begins to ablate and decompose, thereby reducing the heat flow transferred to the substrate 2. After the substrate 2 is heated, the heat radiation is transferred to the surrounding structure. The heat radiation insulation layer provided on the second surface of the substrate 2 reduces the amount of heat radiation exchange. After the first stage of the rocket is recovered, the heat shield is removed and replaced with a new one for the next flight launch mission.

[0033] The thermal protection method achieves graded thermal protection, forming two levels of protection at the bottom of the first stage. First, a heat shield provides the initial thermal protection, creating a high-temperature zone. Then, a heat shield further reduces the temperature of this zone. Simultaneously, the gas within the heat shield cavity isolates the temperature, and the low thermal conductivity of the heat shield itself further reduces the temperature to below 110°C. The heat shield is disassembled and replaced after the first stage re-entries, resulting in higher efficiency. The ablated heat shield is then coated for reuse, achieving a reusable thermal protection system at the bottom of the first stage.

[0034] The first stage of the rocket's flight includes the ascent and reentry phases. First-stage heat protection relies on the substrate 2 and its ablative heat-resistant coating. The ablative coating absorbs heat and then undergoes ablation, reducing the heat transfer to the substrate 2. After heating up, the substrate 2 emits high-temperature thermal radiation, primarily transferred to surrounding structures such as the heat shield 4. Because stainless steel foil 3 is adhered to the surfaces of both the substrate 2 and the heat shield 4, the amount of heat radiation exchange is reduced, resulting in less heat transfer compared to solid-state heat conduction. During the ascent and reentry of the first stage, the air within the groove 7 further isolates the heat. The pressure difference between the inside and outside of the groove 7 is regulated by the air intake and exhaust ports 6.

[0035] After the first stage of the launch vehicle is recovered, the heat shield is removed. Since heat shield 4 absorbs little heat, it will not suffer structural ablation damage. Only a new heat shield needs to be installed to form a new first stage bottom heat shield for the next launch mission. The old heat shield, after removing any remaining ablation-type heat shield coating, can be recoated with a new ablation-type heat shield coating for use on other recovered first stages, thus enabling the rocket's relaunch.

[0036] Compared to existing first-stage bottom heat shields, the thermal protection method in this embodiment utilizes the characteristic that thermal radiation has a lower heat flux than solid-state heat transfer. It employs graded thermal protection based on the temperature tolerance of the heat-resistant materials, dividing the protection range into high-temperature and medium-temperature zones. High-temperature thermal protection is achieved using a heat shield and an ablative thermal coating applied to its surface, while medium-temperature thermal protection is achieved using a heat insulation plate 4. The high-temperature and medium-temperature thermal protection zones are separated by a thermal radiation insulation layer. Upon rocket reentry, only the heat shield in the high-temperature zone needs to be replaced.

[0037] The thermal protection method in this embodiment utilizes the gradual temperature change from high to low in the bottom thermal protection system of the first stage of the rocket, dividing it into high-temperature and medium-temperature thermal protection zones. For reusable rockets, only the high-temperature ablation parts need to be replaced, abandoning the conventional bottom heat shield scheme for the entire rocket. This method is in line with the flight and operational characteristics of reusable rockets, reducing the reuse cost and assembly time of reusable rockets.

[0038] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0039] In this disclosure, relational terms such as first and second are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0040] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0041] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0042] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A reusable thermal protection device for the bottom of a rocket first stage, characterized in that, It includes a heat shield and a heat insulation plate, which are fixed to each other, and a heat insulation cavity is formed between the fixed heat insulation plate and the heat shield. When the rocket is in flight, the heat shield absorbs and insulates the heat. After the rocket is recovered, the heat shield is replaced and can be used for the next rocket launch. The heat shield includes a substrate, a coating, and a heat radiation insulation layer; the coating is disposed on a first surface of the substrate for absorbing heat during rocket flight; the heat radiation insulation layer is disposed on a second surface of the substrate for reducing the amount of heat radiation exchange between the heat shield and the insulation plate during rocket flight; the first surface and the second surface are surfaces of the heat shield that are opposite to each other.

2. The reusable thermal protection device for the bottom of the first stage of a rocket according to claim 1, characterized in that, The surface of the heat insulation board facing the heat protection board is covered with a heat radiation insulation layer.

3. The reusable thermal protection device for the bottom of the first stage of a rocket according to claim 2, characterized in that, The insulation board is a fiberglass composite board.

4. The reusable thermal protection device for the bottom of the first stage of a rocket according to claim 1, characterized in that, The heat insulation plate has a groove on the side facing the heat protection plate, and the groove area has air holes that penetrate both sides of the heat insulation plate in the thickness direction and communicate with the heat insulation cavity.

5. The reusable thermal protection device for the bottom of the first stage of a rocket according to claim 4, characterized in that, The diameter of the pores is 1.5~2.5mm, and multiple pores are arranged in an array with a spacing of 15mm between adjacent pores. The porosity of the heat insulation plate in its groove area is 0.73%.

6. The reusable thermal protection device for the bottom of the first stage of a rocket according to claim 1, characterized in that, A protruding heat insulation pad is provided on the surface of the heat insulation plate facing the heat protection plate. An installation component is provided inside the heat insulation pad, which is used to install the heat protection plate.

7. The reusable thermal protection device for the bottom of a rocket first stage according to claim 1, characterized in that, It also includes structural beams for mounting protective devices onto the rocket.

8. The reusable thermal protection device for the bottom of a rocket first stage according to claim 1, characterized in that, The coating is an ablation-type heat-resistant coating, the substrate is a composite phenolic substrate, and the heat radiation insulation layer is stainless steel foil.

9. The reusable thermal protection device for the bottom of the first stage of a rocket according to claim 8, characterized in that, The thickness of the composite phenolic substrate is 3~5mm, the thickness of the ablation-type heat-resistant coating is 3~6mm, and the thickness of the stainless steel foil is 0.05mm.

10. A reusable thermal protection method for the bottom of a rocket first stage, characterized in that, Install the reusable thermal protection device as described in any one of claims 1 to 9 at the bottom of the first stage of the rocket; During the entire flight of the first stage of the rocket, the first stage of heat protection is provided by the substrate and coating. After absorbing the heat flow, the coating begins to ablate and decompose, thereby reducing the heat flow transferred to the substrate. After the substrate is heated, the heat radiation is transferred to the surrounding structure, and the amount of heat radiation exchange is reduced by the heat radiation insulation layer provided on the second surface of the substrate. After the first stage of the rocket is recovered, the heat shield is removed and replaced with a new one for the next flight launch mission.

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