Rigid-flexible coupling heat-proof skirt for load reduction of reusable rocket engine jet pipe

Abstract

The invention discloses a rigid-flexible coupling heat-proof skirt for load reduction of a reusable rocket engine nozzle. The rigid-flexible coupling heat-proof skirt comprises a sleeve, a heat-proof skirt pressing plate, an upper pressing plate, a lower pressing plate and a flexible heat-proof skirt belt, wherein the sleeve is connected with the rocket tail section; the flexible heat-proof skirt band is arranged in the sleeve; the outer edge of the flexible heat-proof skirt belt is tightly pressed on the sleeve by the heat-proof skirt pressing plate; the heat-proof skirt pressing plate, the flexible heat-proof skirt belt and the sleeve are laminated, pressed and connected; the upper pressing plate is connected with a fireproof plate of the rocket engine; the inner edge of the flexible heat-proof skirt belt is tightly pressed on the upper pressing plate by the lower pressing plate; the lower pressing plate, the flexible heat-proof skirt belt and the upper pressing plate are connected in a stacked and pressed mode. The transverse load of the engine jet pipe is greatly reduced.

Description

Technical Field

[0001] The invention relates to a rigid-flexible coupling heat-resistant skirt for reducing the load on a nozzle of a reusable rocket engine, and belongs to the technical field of aerospace systems. Background Art

[0002] Reusable rockets use the aerodynamic drag generated by the high-speed incoming flow impacting the rocket body to decelerate during the reentry aerodynamic deceleration phase. The rocket body base and engine nozzle face the incoming flow, which is equivalent to the blunt body windward structure. After being impacted by the incoming flow, a detached shock wave is generated and a local high pressure is formed in the central area of ​​the rocket body heat protection bottom. This pressure acts on the base and the engine, resulting in a huge radial outward expansion force and axial force on the rocket body nozzle. At the same time, the heat protection skirt needs to withstand a large external pressure load, and the deformation of the heat protection skirt acts on the connection between it and the engine, which will also generate local radial force and axial force. Under the above combined effects, the return phase load exceeds the load-bearing capacity of the engine and servo mechanism. In order to reduce the load requirements for the servo mechanism and the engine, it is necessary to carry out load optimization design. On this basis, the heat protection skirt is adaptively designed according to the load optimization plan to form a rigid-flexible coupled heat protection skirt.

[0003] Currently, domestic thermal skirts are only suitable for disposable rockets and do not need to withstand the mechanical and thermal loads brought by the high-speed flow in the return phase. They are generally flexible structures, and their materials only need to adapt to the thermal flow environment of the ascent phase, and their shape and size only need to meet the engine swing requirements.

[0004] Foreign reusable rockets use a purely rigid structure. When the engine swings, the rigid structure that swings with the engine requires a large amount of movement space and has a heavy structure.

[0005] The rigid-flexible coupled heat protection skirt structure takes into account the functions of heat protection in the return section, load bearing and reduction of engine nozzle load. It requires little space and its mass is greatly reduced compared to the rigid heat protection skirt.

[0006] According to the flight profile characteristics and load requirements of reusable rockets, the functions of heat skirts include:

[0007] 1) Thermal insulation: In addition to thermal insulation during the ascent, thermal insulation also needs to be maintained during engine ignition and aerodynamic heating during the return stage.

[0008] 2) Follow-up: The flexible part of the heat protection skirt swings with the engine, and its relaxation length should meet the space coordination requirements of the engine swing;

[0009] 3) Load-bearing: In addition to being able to withstand the mechanical and thermal loads of the ascent and return sections, it also needs to adapt to the load-bearing requirements of the engine and servo mechanism. This requirement is mainly met through the dimensional shape of the rigid structure of the heat skirt and the deformation shape of the flexible structure under dynamic pressure.

[0010] Design index requirements include:

[0011] 1) The thermal insulation capacity meets the maximum temperature constraint of the tail cabin space.

[0012] 2) The length of the heat protection skirt should meet the maximum swing angle requirement of the engine.

[0013] 3) Adapt to the extreme lateral load capacity of the first stage engine.

[0014] 4) Adapt to the maximum output force of the first-level servo mechanism.

[0015] 5) Withstand the external pressure load of the return section.

[0016] 6) Bear the cross-sectional load of the connection surface between the heat skirt, tail section and engine. Summary of the invention

[0017] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine, and to achieve a significant reduction in the lateral load on the engine nozzle.

[0018] The technical solution of the present invention is:

[0019] The present invention discloses a rigid-flexible coupling heat-resistant skirt for reducing the load of a reusable rocket engine nozzle, comprising: a sleeve, a heat-resistant skirt pressure plate, an upper pressure plate, a lower pressure plate and a flexible heat-resistant skirt belt; wherein:

[0020] The sleeve is connected to the tail section of the rocket;

[0021] The flexible heat-proof skirt is placed in the sleeve;

[0022] The heat-proof skirt pressing plate presses the outer edge of the flexible heat-proof skirt belt onto the sleeve;

[0023] The heat-proof skirt pressing plate, the flexible heat-proof skirt belt and the sleeve are laminated and pressed tightly together;

[0024] The upper pressure plate is connected to the fireproof plate of the rocket engine;

[0025] The lower pressing plate presses the inner edge of the flexible heat-proof skirt against the upper pressing plate;

[0026] The lower pressing plate, the flexible heat-proof skirt and the upper pressing plate are stacked and pressed tightly together.

[0027] Furthermore, in the above heat-proof skirt, the sleeve comprises an upper end frame, a barrel section, a sleeve heat-proof layer and a lower end frame; wherein,

[0028] The upper frame is connected to the rocket tail section;

[0029] The barrel section is in the shape of an obliquely cut cylinder, with a horizontal upper end surface and an inclined lower end surface;

[0030] The inner surfaces of the upper and lower edges of the barrel section are connected to the upper end frame and the lower end frame respectively;

[0031] The lower end frame is connected to the outer edge of the flexible heat-proof skirt;

[0032] The sleeve heat protection layer is bonded and cured on the outer surface of the barrel section.

[0033] Furthermore, in the above-mentioned heat-proof skirt, the flexible heat-proof skirt belt is formed by laminating silicone rubber-coated glass cloth, flexible insulation felt and silicone rubber-coated Kevlar, and the number of layers and the lamination order are determined according to the heat-proof and load-bearing properties of the material.

[0034] Furthermore, in the above-mentioned heat-proof skirt, the upper pressure plate, the lower pressure plate and the heat-proof skirt pressure plate all adopt a double-layer design; the upper layer is a stainless steel metal structure responsible for bearing, and the lower layer is fiberglass plus a heat-proof coating responsible for heat protection and insulation.

[0035] Furthermore, in the above-mentioned heat-proof skirt, the flexible heat-proof skirt belt is a 360° variable-section rotating body.

[0036] Furthermore, in the above-mentioned heat-proof skirt, the length of the inner and outer cross-sections of the flexible heat-proof skirt is calculated by the formula:

[0037]

[0038] in, is the length of the inner section of the flexible heat-proof skirt, Ri is the radius of the inner compressive deformation state, Hi is the height of the inner compressive deformation state, Li is the length of the inner compressive deformation state, and hi is the inner length of the sleeve at the inner side of the flexible heat-proof skirt; is the outer cross-sectional length of the flexible heat-proof skirt, Ro is the radius of the outer compressive deformation state, Ho is the height of the outer compressive deformation state, Lo is the length of the outer compressive deformation state, ho is the inner length of the sleeve at the outer side of the flexible heat-proof skirt; di is the height difference of the inner flexible heat-proof skirt connection point, do is the height difference of the outer flexible heat-proof skirt connection point.

[0039] Furthermore, in the above-mentioned heat protection skirt, the inclination angle of the lower end surface of the sleeve is designed according to the aerodynamic pressure difference, and the sleeve generatrix on the side with high pressure is longer; the greater the pressure difference, the greater the inclination angle, which is suitable for peripheral swinging engines in a high internal and external pressure difference environment; if there is no pressure difference, the inclination angle is zero, and the sleeve shape is a straight cylinder, which is suitable for central engines that are overall in the high pressure area.

[0040] Furthermore, in the above-mentioned heat-proof skirt, the sleeve, the heat-proof skirt pressure plate, the upper pressure plate and the lower pressure plate are rigid structures, and the flexible heat-proof skirt belt is a flexible structure.

[0041] Furthermore, in the above-mentioned heat-proof skirt, the heat-proof skirt pressure plate, the upper pressure plate and the lower pressure plate are all connected by a multi-piece overlapping manner.

[0042] The beneficial effects of the present invention and the prior art are:

[0043] (1) The present invention provides a heat skirt load optimization design scheme and structural form that utilizes the variable length design of the heat skirt flexible structure along the circumferential direction and the difference in shape after being compressed to increase the outer side lateral bending moment and reduce the inner side lateral bending moment, thereby achieving a significant reduction in the lateral load of the engine nozzle;

[0044] (2) The present invention provides a design that utilizes the variable height of the rigid structure of the heat shield skirt along the circumferential direction to reduce the aerodynamic pressure difference in the internal space thereof, adjust the deformable length of the flexible heat shield skirt, and achieve the adjustment of the load distribution in the rigid structure, thereby reducing the radial outward expansion force and axial force acting on the engine nozzle, as well as the load transmitted to the servo mechanism;

[0045] (3) The present invention adopts the combined load reduction technology of complex mechanical and thermal load analysis and structural design at the bottom of the reusable rocket return stage to design a new type of thermal skirt structure that is suitable for the selection and laying of thermal skirt materials in the continuous mechanical and thermal environment of the reusable rocket ascent stage and return stage, and combines a rigid sleeve with a flexible thermal insulation design;

[0046] (4) The present invention proposes a rigid-flexible coupling heat-resistant skirt structure, which achieves the functional requirements of heat protection, load bearing, and engine nozzle load reduction in the ascent and return stages of reusable rockets at a relatively low cost in space and weight, and promotes the low-cost and rapid transformation of disposable rockets to reusable rockets;

[0047] (5) The present invention can be widely applied to the design of lateral load reduction and high-reliability heat-resistant skirts for engines of various types of reusable rockets. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of heat protection skirt load optimization of the present invention;

[0049] Figure 2 Schematic diagram of the heat protection skirt structure of the peripheral swing engine of the present invention; (a) is a schematic diagram of the oblique cross-section sleeve, (b) is a schematic diagram of the heat protection skirt structure of the peripheral swing engine;

[0050] Figure 3 Schematic diagram of the central engine heat protection skirt structure of the present invention; (a) is a schematic diagram of a flat cross-section sleeve, (b) is a schematic diagram of the central engine heat protection skirt structure;

[0051] Figure 4 It is a schematic diagram of the heat-proof skirt structure of the present invention;

[0052] Figure 5 Schematic diagram of the connection between the heat-proof skirt and the tail section of the present invention;

[0053] Figure 6 Schematic diagram of the connection between the heat protection skirt and the engine of the present invention;

[0054] Figure 7 It is a schematic diagram of the connection between the lower pressing plate, the flexible heat-proof skirt and the upper pressing plate of the present invention;

[0055] Figure 8 It is a schematic diagram of the connection between the heat-proof skirt pressing plate, the flexible heat-proof skirt belt and the sleeve of the present invention;

[0056] Fig. 9 It is a schematic diagram of the structure of the upper pressing plate of the present invention;

[0057] Fig.10 It is a schematic diagram of the structure of the lower pressing plate of the present invention;

[0058] Fig.11 The flexible heat-proof skirt belts of the present invention are of different deformations; (a) is a flexible heat-proof skirt belt with a constant cross-section, and (b) is a flexible heat-proof skirt belt with a variable cross-section;

[0059] Fig.12 1. It is a diagram showing the relationship between the design dimensions of the heat-proof skirt of the present invention; (a) the microelement dimensions and force diagram of the flexible heat-proof skirt, and (b) the dimension relationship between the inner and outer cross-sectional lengths of the flexible heat-proof skirt and the inner and outer lengths of the sleeve. DETAILED DESCRIPTION

[0060] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0061] like Figure 4 As shown, the present invention discloses a rigid-flexible coupling heat-resistant skirt for reducing the load of a reusable rocket engine nozzle, comprising: a sleeve, a heat-resistant skirt pressure plate 5, an upper pressure plate 6, a lower pressure plate 7 and a flexible heat-resistant skirt belt 8;

[0062] in,

[0063] The sleeve is connected to the tail section of the rocket;

[0064] The flexible heat-proof skirt 8 is placed in the sleeve;

[0065] The heat-proof skirt pressing plate 5 presses the outer edge of the flexible heat-proof skirt belt 8 onto the sleeve;

[0066] The heat-proof skirt pressing plate 5, the flexible heat-proof skirt belt 8 and the sleeve are stacked and pressed tightly together;

[0067] The upper pressure plate 6 is connected to the fireproof plate of the rocket engine;

[0068] The lower pressing plate 7 presses the inner edge of the flexible heat-proof skirt 8 onto the upper pressing plate 6;

[0069] The lower pressing plate 7, the flexible heat-proof skirt 8 and the upper pressing plate 6 are stacked and tightly connected.

[0070] Preferably, the sleeve comprises an upper end frame 1, a barrel section 2, a sleeve heat protection layer 3 and a lower end frame 4; wherein,

[0071] The upper frame 1 is connected to the rocket tail section;

[0072] The barrel section 2 is in the shape of an obliquely cut cylinder, with a horizontal upper end surface and an inclined lower end surface;

[0073] The inner surfaces of the upper and lower edges of the barrel section 2 are connected to the upper end frame 1 and the lower end frame 4 respectively;

[0074] The lower end frame 4 is connected to the outer edge of the flexible heat-proof skirt 8;

[0075] The sleeve heat protection layer 3 is bonded and cured on the outer surface of the barrel section 2 .

[0076] Preferably, the flexible heat-proof skirt 8 is formed by laminating silicone rubber-coated glass cloth, flexible heat-insulating felt and silicone rubber-coated Kevlar, and the number of layers and the lamination sequence are determined according to the heat-proof and load-bearing properties of the materials.

[0077] Preferably, the upper pressure plate 6, the lower pressure plate 7 and the heat-proof skirt pressure plate 5 all adopt a double-layer design; the upper layer is a stainless steel metal structure responsible for bearing, and the lower layer is fiberglass with a heat-proof coating responsible for heat protection and insulation.

[0078] Preferably, the flexible heat-proof skirt 8 is a 360° variable-section spiral body, and the cross-sectional length is designed according to the pneumatic pressure difference, with the cross-sectional length being shorter on the side with greater pressure.

[0079] According to the rigid-flexible coupling heat-resistant skirt for reusable rocket engine nozzle load reduction according to claim 1, it is characterized in that the inner and outer cross-sectional lengths of the flexible heat-resistant skirt belt 8 are calculated by the formula:

[0080]

[0081] in, is the length of the inner section of the flexible heat-proof skirt, Ri is the radius of the inner compressive deformation state, Hi is the height of the inner compressive deformation state, Li is the length of the inner compressive deformation state, and hi is the inner length of the sleeve at the inner side of the flexible heat-proof skirt; is the outer cross-sectional length of the flexible heat-proof skirt, Ro is the radius of the outer compressive deformation state, Ho is the height of the outer compressive deformation state, Lo is the length of the outer compressive deformation state, ho is the inner length of the sleeve at the outer side of the flexible heat-proof skirt; di is the height difference of the inner flexible heat-proof skirt connection point, do is the height difference of the outer flexible heat-proof skirt connection point.

[0082] Preferably, the inclination angle of the lower end surface of the sleeve is designed according to the aerodynamic pressure difference, and the sleeve generatrix is ​​longer on the side with higher pressure; the greater the pressure difference, the greater the inclination angle, which is suitable for peripheral swing engines in an environment with high internal and external pressure difference; if there is no pressure difference, the inclination angle is zero, and the sleeve is shaped like a straight cylinder, which is suitable for central engines that are overall in a high pressure area.

[0083] Preferably, the sleeve, the heat-resistant skirt pressure plate 5, the upper pressure plate 6, and the lower pressure plate 7 are rigid structures, and the flexible heat-resistant skirt belt 8 is a flexible structure; the rigid structure bears the complex mechanical and thermal loads of the return segment of the reusable rocket, and reduces the aerodynamic pressure difference in its internal space by designing the inclination angle of the sleeve cross section, and adjusts the deformable length of the flexible heat-resistant skirt; the flexible structure bears the complex mechanical and thermal loads, and affects its shape under the action of the incoming flow by designing its cross-sectional length, thereby balancing the radial outward expansion force on a part of the engine nozzle, thereby achieving the purpose of reducing the load acting on the engine nozzle.

[0084] Preferably, the ply design of the flexible heat-proof skirt 8 adapts to the mechanical and thermal environment of the flight profile. The outer layer is staggered with flexible insulation felt with strong thermal insulation performance and silicone rubber coated glass cloth with good thermal protection performance, which can withstand the heat flow of the ascent and return sections and create a good temperature environment for the inner layer material; the inner layer is staggered with silicone rubber coated glass cloth with good thermal protection performance and Kevlar with strong bearing capacity, which still has the ability to withstand the mechanical and thermal load of the return section after the outer layer material is damaged and loses function.

[0085] Preferably, the heat-proof skirt pressure plate 5, the upper pressure plate 6 and the lower pressure plate 7 are all connected by overlapping multiple pieces, which is convenient for processing and installation on the fireproof plate in the middle of the engine nozzle. The structural thickness of the overlapping part is halved and then overlapped and connected with bolts. The overall thickness remains unchanged and has good continuity.

[0086] Example

[0087] The heat skirt optimizes the height-to-length ratio to achieve load reduction for the reusable rocket engine nozzle. The load optimization ideas for the heat skirt are shown in Figure 1 .

[0088] The load adaptability design of the height of the upper and lower connecting surfaces of the flexible heat-resistant skirt 8 is realized by using the variable height design of the rigid sleeve along the circumferential direction, and the load adaptability design of the length of the flexible heat-resistant skirt is realized by using the variable length design of the flexible heat-resistant skirt between the upper and lower pressure plates 7 along the circumferential direction. According to the load optimization results, the load optimization schemes of the heat-resistant skirt of the peripheral swing engine and the central engine are different. The heat-resistant skirt structure is as follows: Figure 2-Figure 3 shown.

[0089] The heat-proof skirt is composed of a sleeve, a heat-proof skirt pressure plate 5, an upper pressure plate 6, a lower pressure plate 7 and a flexible heat-proof skirt belt 8. The sleeve includes an upper end frame 1, a barrel section 2, a sleeve heat-proof layer 3 and a lower end frame 4. Figure 4 Shown is a connection and heat protection product located between the tail section and the engine.

[0090] The connection between the heat-proof skirt and the tail section is achieved by connecting the upper end frame 1 of the heat-proof skirt sleeve to the tail section bottom plate 52, and the connection between the heat-proof skirt and the engine is achieved by connecting the upper pressure plate 6 to the engine fireproof plate 61. Figure 5-Figure 6 shown.

[0091] like Figure 5 As shown, the upper end frame 1 of the sleeve is connected to the tail section bottom plate 52 of the rocket through bolts 53, washers 54 and self-locking nuts 55.

[0092] like Figure 6 As shown, the engine fireproof plate 61 is connected to the upper layer 62 (metal bearing layer) of the upper pressure plate and the lower layer 63 (non-metal heat protection layer) of the upper pressure plate by bolts 64, washers 65 and self-locking nuts 66.

[0093] The heat-proof skirt pressing plate 5, the flexible heat-proof skirt belt 8 and the sleeve are stacked and pressed tightly, and the heat-proof skirt pressing plate presses the outer edge of the flexible heat-proof skirt belt 8 onto the sleeve; the lower pressing plate 7, the flexible heat-proof skirt belt 8 and the upper pressing plate 6 are stacked and pressed tightly, and the lower pressing plate 7 presses the inner edge of the flexible heat-proof skirt belt 8 onto the upper pressing plate 6, such as Figure 7-Figure 8 shown.

[0094] like Figure 7 As shown, the upper pressing plate upper layer 71 , the upper pressing plate lower layer 72 , the lower pressing plate upper layer 73 , the lower pressing plate lower layer 74 and the flexible heat-proof skirt 8 are connected by bolts 76 , washers 77 and self-locking nuts 78 .

[0095] like Figure 8 As shown, the sleeve lower end frame 4, the flexible heat-proof skirt belt 8, the heat-proof skirt pressure plate upper layer 83 and the heat-proof skirt pressure plate lower layer 84 are connected by bolts 87, washers 88 and self-locking nuts 89.

[0096] The pressure plate is used to press the flexible heat-resistant skirt 8 onto the connection structure. All the pressure plates, including the upper pressure plate 6, the lower pressure plate 7 and the heat-resistant skirt pressure plate 5, are designed in a double layer. The upper layer is a stainless steel metal structure responsible for bearing, and the lower layer is a fiberglass with a heat-resistant coating responsible for heat protection and insulation. The upper and lower pressure plates 7 are connected by overlapping multiple pieces, which is convenient for processing and installation on the fireproof plate in the middle of the engine nozzle. The thickness of the overlapping part is halved and then overlapped and connected with bolts. The overall thickness remains unchanged and has good continuity. Figure 9-10 shown.

[0097] The flexible heat-resistant skirt 8 is made of silicone rubber coated glass cloth + flexible thermal insulation felt + silicone rubber coated Kevlar, and the layer material and number of layers are adaptively designed according to the thermal environment and load conditions. Since the heat-resistant skirt needs to withstand a large aerodynamic external pressure load during return in addition to the heat flow environment conditions, its load-bearing adaptability and air tightness after high-temperature ablation need to be considered. The high strength performance of Kevlar and the airtightness of silicone rubber coated fabric are utilized. The shape of the heat-resistant skirt takes into account the deformation characteristics of the flexible body under static pressure, such as Fig.11 As shown, the shape change is related to the force transmission direction of its connection, which in turn affects the load optimization result and achieves the purpose of further load reduction.

[0098] The height H and length L of the flexible heat-proof skirt 8 are determined according to the load design requirements, such as Fig.12 As shown in a, the heat-resistant skirt microelement force relationship diagram shows that its height and length affect the pressure Ps, tension T, and lateral force F acting on the heat-resistant skirt. x1 and axial force F y1 The inner and outer cross-sectional lengths of the flexible heat-resistant skirt 8 and the inner and outer lengths of the sleeve are based on Fig.12 b Determined by the dimension relationship diagram. The inner section length of the flexible heat-resistant skirt 8 The radius Ri, height Hi, length Li, inner length hi of the sleeve under compression deformation, and the corresponding outer dimensions are Ro, Ho, length Lo, sleeve inner length ho. The height difference of the inner flexible heat-resistant skirt 8 connection point is di, and the height difference of the outer flexible heat-resistant skirt 8 connection point is do. The height differences di and do are determined according to the inner and outer lengths hi and ho of the sleeve and the engine installation position on the arrow. The distance from the engine swing center to the heat-resistant skirt installation plate is L, and the engine swing angle is α. It can be seen from the dimensional relationship diagram that the inner and outer cross-sectional lengths of the flexible heat-resistant skirt 8 are:

[0099]

[0100] Finally check the inner and outer section lengths of the flexible heat-resistant skirt 8 and They should not be less than the sum of the engine swing motion Lα and the initial distance between the connection points of the flexible heat protection skirt 8 to ensure that the length of the heat protection skirt can meet the maximum swing angle requirements of the engine.

[0101] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

[0102] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in the field.

Claims

1. A rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine, characterized in that: include: A sleeve, a heat-resistant skirt pressure plate (5), an upper pressure plate (6), a lower pressure plate (7) and a flexible heat-resistant skirt belt (8); wherein, The sleeve is connected to the tail section of the rocket; The flexible heat-proof skirt (8) is placed in the sleeve; The heat-proof skirt pressing plate (5) presses the outer edge of the flexible heat-proof skirt belt (8) onto the sleeve; The heat-proof skirt pressing plate (5), the flexible heat-proof skirt belt (8) and the sleeve are stacked and pressed tightly together; The upper pressing plate (6) is connected to the fireproof plate of the rocket engine; The lower pressing plate (7) presses the inner edge of the flexible heat-proof skirt (8) onto the upper pressing plate (6); The lower pressing plate (7), the flexible heat-proof skirt (8) and the upper pressing plate (6) are stacked and tightly connected.

2. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The sleeve comprises an upper end frame (1), a sleeve section (2), a sleeve heat protection layer (3) and a lower end frame (4); wherein: The upper end frame (1) is connected to the rocket tail section; The barrel section (2) is in the shape of an obliquely cut cylinder, with a horizontal upper end surface and an inclined lower end surface; The inner surfaces of the upper and lower edges of the barrel section (2) are connected to the upper end frame (1) and the lower end frame (4) respectively; The lower end frame (4) is connected to the outer edge of the flexible heat-proof skirt (8); The sleeve heat protection layer (3) is bonded and cured on the outer surface of the barrel section (2).

3. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The flexible heat-proof skirt (8) is formed by laminating silicone rubber-coated glass cloth, flexible heat-insulating felt and silicone rubber-coated Kevlar, and the number of layers and the lamination sequence are determined according to the heat-proof and load-bearing properties of the materials.

4. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The upper pressing plate (6), the lower pressing plate (7) and the heat-proof skirt pressing plate (5) all adopt a double-layer design; the upper layer is a stainless steel metal structure responsible for bearing, and the lower layer is a glass fiber reinforced plastic with a heat-proof coating responsible for heat protection and heat insulation.

5. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The flexible heat-proof skirt (8) is a 360° variable-section rotating body.

6. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 5, characterized in that: The length of the inner and outer cross-sections of the flexible heat-proof skirt (8) is calculated by the formula: in, is the length of the inner section of the flexible heat-proof skirt, Ri is the radius of the inner compressive deformation state, Hi is the height of the inner compressive deformation state, Li is the length of the inner compressive deformation state, and hi is the inner length of the sleeve at the inner side of the flexible heat-proof skirt; is the outer cross-sectional length of the flexible heat-proof skirt, Ro is the radius of the outer compressive deformation state, Ho is the height of the outer compressive deformation state, Lo is the length of the outer compressive deformation state, ho is the inner length of the sleeve at the outer side of the flexible heat-proof skirt; di is the height difference of the inner flexible heat-proof skirt connection point, do is the height difference of the outer flexible heat-proof skirt connection point.

7. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The inclination angle of the lower end surface of the sleeve is designed according to the aerodynamic pressure difference, and the sleeve generatrix is ​​longer on the side with higher pressure; the greater the pressure difference, the greater the inclination angle, which is suitable for peripheral swinging engines in a high internal and external pressure difference environment; if there is no pressure difference, the inclination angle is zero, and the sleeve shape is a straight cylinder, which is suitable for central engines that are overall in the high pressure area.

8. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The sleeve, the heat-proof skirt pressure plate (5), the upper pressure plate (6) and the lower pressure plate (7) are rigid structures, and the flexible heat-proof skirt belt (8) is a flexible structure.

9. The rigid-flexible coupled heat-resistant skirt for reducing the load on the nozzle of a reusable rocket engine according to claim 1, characterized in that: The heat-proof skirt pressing plate (5), the upper pressing plate (6) and the lower pressing plate (7) are all connected by a multi-piece overlapping manner.

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