阅读说明：本技术 一种环状波纹柔性防热套及其制备方法 (Annular corrugated flexible heat-proof sleeve and preparation method thereof ) 是由 艾进 张权 郑张宜 张天胤 谢道成 葛新成 沈亚东 于 2020-12-31 设计创作，主要内容包括：本发明实施例提供了一种环状波纹柔性防热套及其制备方法,所述防热套为环形且沿圆周方向呈波浪形,所述防热套沿圆周方向包括:力学增强层：具有相对设置的第一表面和第二表面；柔性耐热层：与所述第一表面相贴合；反热辐射层：为铝粉掺杂硅橡胶,所述反热辐射层与所述第二表面相贴合。所述方法包括：获得具有腔体的模具,所述腔体为环形且沿圆周方向呈波浪形；将所述模具的内表面喷涂脱膜剂后,将所述柔性耐热层、力学增强层和反热辐射层铺在所述腔体内,加热加压,后脱模获得。该防热套具有一定弹性、强度和抗烧蚀性,安装在尾段与发动机摆动喷管之间的环形间隙部位,以防止喷管出口高温燃流反窜入尾段舱内以及飞行过程中尾段底部防热。(The embodiment of the invention provides an annular corrugated flexible heat-proof sleeve and a preparation method thereof, wherein the heat-proof sleeve is annular and is wavy along the circumferential direction, and the heat-proof sleeve comprises a mechanical enhancement layer: having oppositely disposed first and second surfaces; flexible heat-resistant layer: the first surface is attached; a heat-reflecting radiation layer: the aluminum powder is doped with silicon rubber, and the heat-reflecting radiation layer is attached to the second surface. The method comprises the following steps: obtaining a die with a cavity, wherein the cavity is annular and is wavy along the circumferential direction; and after spraying a release agent on the inner surface of the mold, paving the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer in the cavity, heating and pressurizing, and demolding to obtain the heat-resistant composite material. The heat-proof sleeve has certain elasticity, strength and ablation resistance, and is arranged at an annular gap part between the tail section and the engine swinging spray pipe to prevent high-temperature combustion flow at the outlet of the spray pipe from reversely flowing into a tail section cabin and prevent the bottom of the tail section from being heated in the flying process.)

1. The utility model provides a flexible heat shield of annular ripple, its characterized in that, the heat shield is the annular and is the wave along the circumferencial direction, the heat shield includes along the circumferencial direction:

mechanical enhancement layer: having oppositely disposed first and second surfaces;

flexible heat-resistant layer: the first surface is attached;

a heat-reflecting radiation layer: the aluminum powder is doped with silicon rubber, and the heat-reflecting radiation layer is attached to the second surface.

2. The flexible heat shield of claim 1, wherein the ratio of the thicknesses of the flexible heat-resistant layer, the mechanical-enhancement layer, and the heat-reflective radiation layer is: (0.7-0.8): (2.2-2.3): (0.7-0.8).

3. The annular corrugated flexible heat-proof sleeve as claimed in claim 1, wherein the aluminum powder doped silicone rubber contains 1-5% by mass of aluminum powder.

4. The flexible heat shroud of claim 1, wherein said flexible heat resistant layer is silicone rubber.

5. The annular corrugated flexible heat shroud as claimed in claim 1, wherein said mechanical reinforcement layer is silica glass fiber reinforced glue.

6. A method of making an annularly corrugated flexible heat shroud as claimed in any one of claims 1 to 5, wherein said method includes:

obtaining a die with a cavity, wherein the cavity is annular and is wavy along the circumferential direction; the die comprises an upper die and a lower die which are connected;

after spraying a release agent on the surfaces of the upper die and the lower die, paving the flexible heat-resistant layer, the mechanical enhancement layer and the heat-reflecting radiation layer on the surface of the lower die, and then closing the lower die and the upper die to obtain a composite material blank;

and (3) heating and pressurizing the composite material blank, and then demolding to obtain the annular corrugated flexible heat-proof sleeve.

7. The annular corrugated flexible heat-proof sleeve as claimed in claim 6, wherein the spraying is performed for 2-3 times, the time interval between two adjacent spraying is 15-20 min, and the total spraying amount is 45-55 g/m²。

8. The method for preparing the annular corrugated flexible heat-proof sleeve according to claim 6, wherein the heating temperature is 100-175 ℃, and the heating time is 0.5-1.5 h.

9. The method for preparing the annular corrugated flexible heat-proof sleeve as claimed in claim 6, wherein the pressure is controlled to be 180-220 t during the pressurization.

10. The method for preparing the annular corrugated flexible heat-proof sleeve as claimed in claim 6, wherein in the die assembly, the gap between the upper die and the lower die after die assembly is controlled to be less than or equal to 0.05 mm.

Technical Field

The invention belongs to the technical field of heat-proof sleeve composite materials, and particularly relates to an annular corrugated flexible heat-proof sleeve and a preparation method thereof.

Background

When the engine works, the outlet of the spray pipe generates heat flow with the temperature of about 600 ℃, and the heat flow can reversely flow into the tail section cabin during the attitude adjustment or the flight process. Therefore, the heat release sleeve is required to be arranged between the tail section and the engine spray pipe, the heat-proof sleeve is made of glass fiber reinforced plastic materials and is made of rigid materials, the spray pipe needs to swing when the engine works, the rigid materials are poor in elasticity, the normal work of the spray pipe cannot be achieved, and the ablation resistance performance is poor.

Therefore, how to provide an annular corrugated flexible heat-proof sleeve with good elasticity, good ablation resistance and certain strength and a preparation method thereof becomes a technical problem to be solved urgently.

Disclosure of Invention

The invention provides an annular corrugated flexible heat-proof sleeve and a preparation method thereof, wherein the heat-proof sleeve has certain elasticity, strength and ablation resistance, and is arranged at an annular gap part between a tail section and an engine swinging spray pipe so as to prevent high-temperature combustion flow at the outlet of the spray pipe from reversely flowing into a tail section cabin and prevent the bottom of the tail section from being heated in the flight process.

In order to solve the above technical problem, an embodiment of the present invention provides an annular corrugated flexible heat-proof jacket, where the heat-proof jacket is annular and wavy along a circumferential direction, and the heat-proof jacket includes:

mechanical enhancement layer: having oppositely disposed first and second surfaces;

flexible heat-resistant layer: the first surface is attached;

a heat-reflecting radiation layer: the aluminum powder is doped with silicon rubber, and the heat-reflecting radiation layer is attached to the second surface.

Further, the thickness ratio of the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer is as follows: (0.7-0.8): (2.2-2.3): (0.7-0.8).

Further, the mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 1-5%.

Further, the flexible heat-resistant layer is silicon rubber.

Further, the mechanical enhancement layer is quartz glass fiber reinforced glue.

The embodiment of the invention provides a preparation method of an annular corrugated flexible heat-proof sleeve, which comprises the following steps:

obtaining a die with a cavity, wherein the cavity is annular and is wavy along the circumferential direction; the die comprises an upper die and a lower die which are connected;

after spraying a release agent on the surfaces of the upper die and the lower die, paving the flexible heat-resistant layer, the mechanical enhancement layer and the heat-reflecting radiation layer on the surface of the lower die, and then closing the lower die and the upper die to obtain a composite material blank;

and (3) heating and pressurizing the composite material blank, and then demolding to obtain the annular corrugated flexible heat-proof sleeve.

Furthermore, in the spraying, the spraying frequency is 2-3 times, the time interval between two adjacent spraying is 15-20 min, and the total spraying amount is 45-55 g/m²。

Further, the heating temperature is 100-175 ℃, and the heating time is 0.5-1.5 h.

Furthermore, in the pressurization, the pressure is controlled to be 180-220 t.

Furthermore, in the die assembly, the gap between the upper die and the lower die after die assembly is controlled to be less than or equal to 0.05 mm.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

the embodiment of the invention provides an annular corrugated flexible heat-proof sleeve and a preparation method thereof, wherein the annular corrugated flexible heat-proof sleeve is made of three layers of materials, and the flexible heat-resistant layer can enable the annular corrugated flexible heat-proof sleeve to have certain flexibility so as to protect a spray pipe from swinging; the mechanical enhancement layer can improve the strength of the annular corrugated flexible heat-proof sleeve, and the strength range is 2-6 MPa; the heat-reflecting radiation layer is formed by dispersing aluminum powder in silicon rubber, and the aluminum powder-doped silicon rubber is cured along with the rubber, mainly has good dispersibility, and then can be randomly changed in shape; and the silicon rubber can be vulcanized in the heating and pressurizing process to form a continuous metal film, the silicon rubber is covered, and the reflection can be formed on heat, so that the silicon rubber has good ablation resistance.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an annular corrugated flexible heat-proof sleeve according to an embodiment of the present invention;

FIG. 2 is a top view of an annular corrugated flexible heat shroud according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method for manufacturing the annular corrugated flexible heat-proof jacket according to an embodiment of the present invention;

FIG. 4 is a temperature profile of ablation resistance test;

in the figure, 1-an upper die, 2-a lower die, 3-a flexible heat-resistant layer, 4-a mechanical enhancement layer, 5-a heat-reflecting radiation layer and 6-a cavity;

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.

Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

In order to solve the technical problems, the embodiment of the invention provides the following general ideas:

according to a typical implementation manner of the embodiment of the invention, an annular corrugated flexible heat-proof sleeve is provided, the heat-proof sleeve is annular and is wavy along the circumferential direction, and the heat-proof sleeve comprises the following components along the circumferential direction:

mechanical enhancement layer: having oppositely disposed first and second surfaces;

flexible heat-resistant layer: the first surface is attached;

a heat-reflecting radiation layer: the aluminum powder is doped with silicon rubber, and the heat-reflecting radiation layer is attached to the second surface.

In the present embodiment, the first and second embodiments are described,

the flexible heat-resistant layer can enable the annular corrugated flexible heat-proof sleeve to have certain flexibility, so that the spray pipe is protected from swinging;

the mechanical enhancement layer can improve the strength of the annular corrugated flexible heat-proof sleeve, and the strength range reaches 2-6 MPa, so that the product can be resisted to bear violent swinging during working;

the heat-reflecting radiation layer is formed by dispersing aluminum powder in silicon rubber, and the aluminum powder-doped silicon rubber is cured along with the rubber, mainly has good dispersibility, and then can be randomly changed in shape; and the silicon rubber can be vulcanized in the heating and pressurizing process to form a continuous metal film, the silicon rubber is covered, and the reflection can be formed on heat, so that the silicon rubber has good ablation resistance and has good ablation resistance.

As an implementation manner of the embodiment of the present invention, a thickness ratio of the flexible heat-resistant layer, the mechanical enhancement layer, and the heat-reflecting radiation layer is: (0.7-0.8): (2.2-2.3): (0.7-0.8). The reason why the thickness ratio is set within the range is to provide sufficient heat resistance, ablation resistance, strength, and the like; the flexible heat-resistant layer is too thick, so that the strength is easily too low, and the ablation amount is easily large due to too small thickness; the mechanical enhancement layer is too thick, so that the elasticity is insufficient easily, and is too small, so that the strength is low easily; the product strength is low due to the fact that the thickness of the heat reflection radiation layer is too large, cracks are easy to generate, the appearance quality is poor, and the back surface temperature is high due to the fact that the thickness of the heat reflection radiation layer is too small;

as an implementation manner of the embodiment of the present invention, the thicknesses of the flexible heat-resistant layer, the mechanical enhancement layer, and the heat-reflecting radiation layer are 0.75mm, 2.25mm, and 0.75mm, respectively;

as an implementation manner of the embodiment of the invention, the mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 1-5%. The arrangement is favorable for fully dispersing aluminum powder in the adhesive film and easily forming a continuous metal film;

as an implementation manner of the embodiment of the present invention, the flexible heat-resistant layer is silicon rubber. The silicon rubber is a good flexible heat-resistant material because of flexibility and heat resistance;

as an implementation manner of the embodiment of the present invention, the mechanical enhancement layer is quartz glass fiber reinforced glue. The quartz glass fiber reinforced glue is made of crystal or pure SiO₂Is a quartz glass fiber reinforced material prepared by melting and drawing or rod drawing and other methods, and SiO thereof₂The content reaches 99.9 percent. Because the adhesive film contains quartz glass fiber, the hardness after molding reaches 40-60;

as an implementation mode of the embodiment of the invention, the crest distance of two adjacent waves of the annular corrugated flexible heat-proof sleeve is 20-40mm, the distance of two connected wave troughs is 20-40mm, and the number of the waves is 2; the difference value between the inner diameter and the outer diameter of the annular corrugated flexible heat-proof sleeve is 400 mm. The reason for this is: the wave shape is adapted to the shape of the annular gap between the tail section and the engine nozzle in the prior art; therefore, the heat shield can be used at the annular gap part between the tail section and the engine jet pipe to prevent high-temperature combustion flow at the outlet of the jet pipe from reversely flowing into the tail section cabin and prevent the bottom of the tail section from being heated in the flying process.

According to another exemplary embodiment of the present invention, there is provided a method for manufacturing the annular corrugated flexible heat-proof jacket, the method including:

s1, obtaining a die with a cavity, wherein the cavity is annular and is wavy along the circumferential direction; the die comprises an upper die and a lower die which are connected;

s2, spraying a release agent on the surfaces of the upper die and the lower die, paving the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer on the surface of the lower die, and then closing the lower die and the upper die to obtain a composite material blank;

in the step S2, in the step S,

the mold release agent comprises one of PMR and LPT-02, and is convenient for demolding after subsequent heating and pressurization;

in the spraying process, the spraying frequency is 2-3 times, the time interval of two adjacent spraying is 15-20 min, and the total spraying amount is 45-55 g/m². The arrangement is favorable for the release agent to be fully cured on the surface of the mould to form a uniform film;

in the laying process, because the flexible heat-resistant layer is of an annular (including a circular ring shape and an elliptical ring shape) and has a corrugated structure, the whole silicon rubber cannot be used for laying, so that the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer are laid on the surfaces of the upper die and the lower die in a split mode, and the method comprises the following steps: cutting: cutting the heat-resistant layer, the mechanical enhancement layer and the heat-reflecting radiation layer in sequence according to a product development diagram; layering: paving a heat-resistant layer, a mechanical enhancement layer and a heat-reflecting radiation layer in sequence: specifically, heat-resistant layers are clockwise layered along the circumferential direction of the die, and the lapping width of each heat-resistant layer adhesive film is 60-100 mm; after finishing, performing mechanical reinforcement layer laying, wherein the lapping positions of the mechanical reinforcement layer laying and the heat-resistant layer are required to be staggered, namely the lapping positions between the layers are not allowed to be overlapped; after finishing, performing heat reflection radiation layer layering, wherein the lapping positions of the heat reflection radiation layer layering and the mechanical enhancement layer are required to be staggered, namely the lapping positions among the layers are not allowed to be overlapped;

and S3, heating and pressurizing the composite material blank, and demolding to obtain the annular corrugated flexible heat-proof sleeve.

In the step S3, in the step S,

the heating temperature is 100-175 ℃, and the heating time is 0.5-1.5 h. If the heating temperature is less than 100 ℃, the heating time is less than 0.5h, the silicon rubber is easy to be insufficiently vulcanized; if the heating temperature is higher than 175 ℃ and the heating time is longer than 1.5h, the silicone rubber is easy to be over-vulcanized, and the material is hard;

specifically, the room temperature is heated to 175 ℃, the heat preservation time is 1h, the temperature rise time is 2h, and the temperature rise rate is 70-80 ℃/h;

and in the pressurization, the pressure is controlled to be 180-220 t. If the pressure is too low, the heat-resistant layer, the mechanical enhancement layer and the heat-reflecting radiation layer are not fused enough, layering is easy, and rubber is heated and flows to overflow the die due to overlarge pressure, so that material shortage is caused;

in the die assembly, the gap between the upper die and the lower die after die assembly is controlled to be less than or equal to 0.05 mm. The arrangement is favorable for controlling the thickness of the product;

the following will explain in detail a ring-shaped corrugated flexible heat-proof jacket and a method for manufacturing the same according to the present invention with reference to examples, comparative examples and experimental data.

Example 1

The embodiment of the invention provides a preparation method of an annular corrugated flexible heat-proof sleeve, which comprises the following specific steps:

1. spraying a release agent:

spraying the release agent on the surface of the upper die 1 and the surface of the lower die 2 by a low-pressure spray gun for 2 times at an interval of 15min, wherein the total spraying amount of the upper die is 50g/m²The total spraying amount of the lower die is 50g/m²。

2. Layering:

silicon rubber, quartz glass fiber reinforced rubber and aluminum powder-doped silicon rubber are sequentially paved on the surface of a cavity of a lower die 2, and the layers are lapped to form a heat-resistant layer 3, a mechanical enhancement layer 4 and a heat-reflecting radiation layer 5, wherein the lapping width is 60mm, and the interlayer lapping strength is staggered. The thicknesses of the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer are respectively as follows: 0.75mm, 2.25mm, 0.75 mm. The mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 1%;

3. die assembly:

the upper die 1 and the lower die 2 are clamped.

4. And (3) vulcanization:

the curing system is as follows: heating the mixture to 175 ℃, keeping the temperature for 1h, heating the mixture for 2h, and heating the mixture at a rate of 70 ℃/h; the pressure was 200T.

5. Demolding:

and after vulcanization, opening the mold, and cutting the flash to obtain the annular corrugated flexible heat-proof sleeve.

Example 2

The embodiment of the invention provides a preparation method of an annular corrugated flexible heat-proof sleeve, which comprises the following specific steps:

1. spraying a release agent:

spraying the release agent on the surface of the upper die 1 and the surface of the lower die 2 by a low-pressure spray gun for 3 times at an interval of 16min, wherein the total spraying amount of the upper die is 45g/m²The total spraying amount of the lower die is 45g/m²。

2. Layering:

silicon rubber, quartz glass fiber reinforced rubber and aluminum powder-doped silicon rubber are sequentially paved on the surface of a cavity of a lower die 2, and the layers are lapped to form a heat-resistant layer 3, a mechanical enhancement layer 4 and a heat-reflecting radiation layer 5, wherein the lapping width is 80mm, and the interlayer lapping strength is staggered. The thicknesses of the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer are respectively as follows: 0.7mm, 2.2mm, 0.7 mm. The mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 5%;

3. die assembly:

the upper die 1 and the lower die 2 are clamped.

4. And (3) vulcanization:

the curing system is as follows: heating the mixture to 170 ℃ at room temperature, keeping the temperature for 1.5h, heating the mixture for 2.5h at a heating rate of 75 ℃/h; the pressure was 205T.

5. Demolding:

and after vulcanization, opening the mold, and cutting the flash to obtain the annular corrugated flexible heat-proof sleeve.

Example 3

The embodiment of the invention provides a preparation method of an annular corrugated flexible heat-proof sleeve, which comprises the following specific steps:

1. spraying a release agent:

spraying the release agent on the surface of the upper die 1 and the surface of the lower die 2 by a low-pressure spray gun for 3 times at an interval of 16min, wherein the total spraying amount of the upper die is 55g/m²The total spraying amount of the lower die is 55g/m²。

2. Layering:

silicon rubber, quartz glass fiber reinforced rubber and aluminum powder-doped silicon rubber are sequentially paved on the surface of a cavity of a lower die 2, and the layers are lapped to form a heat-resistant layer 3, a mechanical enhancement layer 4 and a heat-reflecting radiation layer 5, wherein the lapping width is 80mm, and the interlayer lapping strength is staggered. The thicknesses of the flexible heat-resistant layer, the mechanical enhancement layer and the heat reflection radiation layer are respectively as follows: 0.8mm, 2.3mm, 0.8 mm. The mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 3%;

3. die assembly:

the upper die 1 and the lower die 2 are clamped.

4. And (3) vulcanization:

the curing system is as follows: heating the mixture to 170 ℃ at room temperature, keeping the temperature for 1.5h, heating the mixture for 2.5h at a heating rate of 80 ℃/h; the pressure was 205T.

5. Demolding:

and after vulcanization, opening the mold, and cutting the flash to obtain the annular corrugated flexible heat-proof sleeve.

Comparative example 1

This comparative example does not contain a heat-reflecting layer, and the other steps are the same as in example 1.

Comparative example 2

The mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber of the heat reflection radiation layer in the comparative example is 0.5%, and other steps are the same as those in example 1.

Comparative example 3

The mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber of the heat reflection radiation layer in the comparative example is 8%, and other steps are the same as those in example 1.

Experimental example 1

For the sake of easy comparison, each parameter of examples 1 to 3 and comparative examples 1 to 3 is tabulated in table 1;

TABLE 1

The properties of the annular corrugated flexible heat shield sleeves of examples 1 to 3 and comparative examples 1 to 3 are shown in table 2, wherein the test conditions for ablation resistance: the temperature profile for the ablation resistance test shown in FIG. 4 was used;

TABLE 2

Group of	Strength of	Indication of ablation resistance	Index of elasticity
				Example 1	4.5MPa	The ablation depth is 0.12mm, the back surface temperature is 78 DEG C	The inflation pressure is 11000Pa, and the fracture elongation is 343 percent
Example 2	2.89MPa	The ablation depth is 0.06mm, the back surface temperature is 63 DEG C	Inflation pressure 10500Pa, and elongation at break 325%
				Example 3	3.31MPa	The ablation depth is 0.03mm, the back surface temperature is 45 DEG C	Inflation pressure 11300Pa, elongation at break 309%
Comparative example 1	2.36MPa	The ablation depth is 1.1mm, the back surface temperature is 138 DEG C	Inflation pressure 8000Pa, and fracture elongation rate 430%
				Comparative example 2	2.40MPa	The ablation depth is 0.9mm, the back surface temperature is 108 DEG C	Inflation pressure 10000Pa and fracture elongation rate 265%
Comparative example 3	1.57MPa	The ablation depth is 0.05mm, the back surface temperature is 58 DEG C	The inflation pressure is 7000Pa, and the fracture elongation is 147%

From the data in table 2, it can be seen that:

in comparative example 1, the heat-reflecting radiation layer was not contained, and the other steps were the same as in example 1, and the defects of large ablation amount and high back temperature were observed;

in the comparative example 2, the mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 0.5 percent and is less than the range of 1-5 percent in the embodiment of the invention, and the other steps are the same as the embodiment 1, so that the defects of large ablation amount and high back temperature exist;

in the comparative example 3, the mass fraction of the aluminum powder in the aluminum powder-doped silicone rubber is 8% and is larger than the range of 1-5% in the embodiment of the invention, and the other steps are the same as those in the embodiment 1, so that the defect of low strength exists;

the annular corrugated flexible heat-proof sleeve prepared in the embodiment 1-the embodiment 3 has better elasticity, strength and ablation resistance; the nozzle is arranged at the annular gap part between the tail section and the engine swinging nozzle to prevent high-temperature fuel flow at the nozzle outlet from reversely flowing into the tail section cabin and prevent the bottom of the tail section from being heated in the flying process.

Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.