Solid rocket engine long tail nozzle and its external heat insulation device

Abstract

The application relates to a solid rocket engine long tail nozzle and an outer heat insulation device thereof, wherein the outer heat insulation device comprises a front support frame, a rear support frame, an inner heat insulation cylinder and an outer heat insulation cylinder; the front support frame is provided with a long tail nozzle front section mounting hole, the outer side of the long tail nozzle front section mounting hole is provided with an inner heat insulation cylinder front end mounting groove and an outer heat insulation cylinder front end mounting groove; the rear support frame is provided with a long tail nozzle rear section mounting hole, the outer side of the long tail nozzle rear section mounting hole is provided with an inner heat insulation cylinder rear end mounting groove and an outer heat insulation cylinder rear end mounting groove; the outer side of the long tail nozzle rear section mounting hole is provided with an inner baffle and an outer baffle in the axial direction; the two ends of the inner heat insulation cylinder are connected with the inner heat insulation cylinder front end mounting groove and the inner heat insulation cylinder rear end mounting groove respectively; and the two ends of the outer heat insulation cylinder are connected with the outer heat insulation cylinder front end mounting groove and the outer heat insulation cylinder rear end mounting groove respectively. The outer heat insulation device in the application has the advantages of simple structure, low negative mass, good heat insulation performance, easy bonding forming, good environmental adaptability, effective limiting, flame and heat flow backflow prevention and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of rocket engines, and particularly relates to a solid rocket engine long tail nozzle and an external heat insulation device thereof. BACKGROUND

[0002] In recent years, due to the limitation of installation space or the requirement of static stability, the solid rocket engine long tail nozzle is more and more widely used in tactical missiles. In order to prevent the temperature of the long tail nozzle shell from being too high during the working of the solid rocket engine, which leads to the decrease of the shell strength and the influence on the working reliability of the electronic instruments and equipment around the long tail nozzle, the surface temperature of the long tail nozzle shell of the solid rocket engine is generally strictly limited, and the long tail nozzle needs to be heat protected.

[0003] At present, the conventional heat protection of the long tail nozzle is to increase a hard ablation-resistant layer in the long tail nozzle shell (a rubber heat insulation layer can be added in the middle if necessary) to achieve the purpose of heat protection. When the hard ablation-resistant layer is heated, most of the heat transferred from the gas is absorbed through the phase change (melting, evaporation and sublimation) and high-temperature decomposition of the material of the hard ablation-resistant layer. Since the products of the phase change and thermal decomposition continuously escape and wash away from the surface of the heat insulation layer, not only the heat is taken away, but also the gas does not contact the solid wall, thereby reducing the heat transfer coefficient and the temperature of the gas near the surface, greatly weakening the heat flow to the protected member, and achieving the purpose of heat insulation. At the same time, the small thermal conductivity coefficient and poor thermal conductivity of the hard ablation-resistant layer can further achieve the purpose of heat insulation. The solid rocket engine with short working time can achieve the heat protection requirement by using the conventional structure.

[0004] However, when the conventional structure is used for the solid rocket engine with long working time, some problems exist. Since the working time is long, the heat exchange amount at the long tail nozzle is very large. If the surface temperature of the long tail nozzle shell is to be reached, the thickness of the hard ablation-resistant layer will be very thick, which greatly increases the negative mass and reduces the performance of the solid rocket engine. SUMMARY

[0005] The present application aims to provide a solid rocket engine long tail nozzle and an external heat insulation device thereof, so as to solve the problems of large negative mass and high temperature of the long tail nozzle of the solid rocket engine working for a long time under the existing heat protection structure.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] An external heat insulation device of a solid rocket engine long tail nozzle, comprising a front support frame, a rear support frame, an inner heat insulation cylinder and an outer heat insulation cylinder.

[0008] The front support frame is provided with a long tail nozzle front section mounting hole, and the outer side of the long tail nozzle front section mounting hole is provided with an inner heat insulation cylinder front end mounting groove and an outer heat insulation cylinder front end mounting groove.

[0009] The rear support is provided with a long tail nozzle rear section mounting hole, and the outer side of the long tail nozzle rear section mounting hole is provided with an inner heat insulation cylinder rear end mounting slot and an outer heat insulation cylinder rear end mounting slot; the outer side of the long tail nozzle rear section mounting hole is axially provided with an inner baffle and an outer baffle;

[0010] The two ends of the inner heat insulation cylinder are connected with the inner heat insulation cylinder front end mounting slot and the inner heat insulation cylinder rear end mounting slot respectively; the two ends of the outer heat insulation cylinder are connected with the outer heat insulation cylinder front end mounting slot and the outer heat insulation cylinder rear end mounting slot respectively.

[0011] Preferably, the inner diameter of the front part of the long tail nozzle front section mounting hole decreases from outside to inside, and the inner diameter of the rear part of the long tail nozzle front section mounting hole is the same.

[0012] Preferably, the bottom of the inner heat insulation cylinder front end mounting slot is circumferentially uniformly provided with a plurality of inner heat insulation cylinder front end arc-shaped positioning holes, the inner heat insulation cylinder front end is circumferentially uniformly provided with a plurality of inner heat insulation cylinder front end arc-shaped positioning plug plates, and the plurality of inner heat insulation cylinder front end arc-shaped positioning plug plates are connected with the plurality of inner heat insulation cylinder front end arc-shaped positioning holes.

[0013] Preferably, the bottom of the outer heat insulation cylinder front end mounting slot is circumferentially uniformly provided with a plurality of outer heat insulation cylinder front end arc-shaped positioning holes, the outer heat insulation cylinder front end is circumferentially uniformly provided with a plurality of outer heat insulation cylinder front end arc-shaped positioning plug plates, and the plurality of outer heat insulation cylinder front end arc-shaped positioning plug plates are connected with the plurality of outer heat insulation cylinder front end arc-shaped positioning holes.

[0014] Preferably, the inner heat insulation cylinder front end arc-shaped positioning hole is a through hole, and the outer heat insulation cylinder front end arc-shaped positioning hole is a through hole.

[0015] Preferably, the outer surface of the front support is axially provided with an inner heat insulation cylinder front end socket and an outer heat insulation cylinder front end socket, the inner heat insulation cylinder front end mounting slot is arranged in the inner heat insulation cylinder front end socket, and the outer heat insulation cylinder front end mounting slot is arranged in the outer heat insulation cylinder front end socket.

[0016] Preferably, the bottom of the inner heat insulation cylinder rear end mounting slot is circumferentially uniformly provided with a plurality of inner heat insulation cylinder rear end arc-shaped positioning holes, the inner heat insulation cylinder rear end is circumferentially uniformly provided with a plurality of inner heat insulation cylinder rear end arc-shaped positioning plug plates, and the plurality of inner heat insulation cylinder rear end arc-shaped positioning plug plates are connected with the plurality of inner heat insulation cylinder rear end arc-shaped positioning holes.

[0017] Preferably, the bottom of the outer heat insulation cylinder rear end mounting slot is circumferentially uniformly provided with a plurality of outer heat insulation cylinder rear end arc-shaped positioning holes, the outer heat insulation cylinder rear end is circumferentially uniformly provided with a plurality of outer heat insulation cylinder rear end arc-shaped positioning plug plates, and the plurality of outer heat insulation cylinder rear end arc-shaped positioning plug plates are connected with the plurality of outer heat insulation cylinder rear end arc-shaped positioning holes.

[0018] Preferably, the outer surface of the rear support frame is provided with an inner heat insulation cylinder rear end socket and an outer heat insulation cylinder rear end socket in the axial direction, the inner heat insulation cylinder rear end mounting groove is arranged in the inner heat insulation cylinder rear end socket, and the outer heat insulation cylinder rear end mounting groove is arranged in the outer heat insulation cylinder rear end socket.

[0019] Preferably, the inner heat insulation cylinder rear end arc-shaped positioning hole is a blind hole, and the outer heat insulation cylinder rear end arc-shaped positioning hole is a blind hole.

[0020] Preferably, the distance between the inner baffle and the outer baffle is 5-20 mm.

[0021] A solid rocket engine long tail nozzle comprises the outer heat insulation device described in any of the above.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] 1. The hard phenolic resin material adopted in the present application is simple in structure and easy to obtain, has the characteristics of high temperature resistance, low thermal conductivity and high strength, and the whole preparation process does not involve complex process steps, and the finished product rate is high.

[0024] 2. The present application uses air for heat insulation, which not only reduces the mass of the device, but also has good heat insulation performance.

[0025] 3. The arc-shaped positioning holes designed on the front support frame and the rear support frame effectively ensure the axial positioning of the inner and outer heat insulation cylinders, and further enhance the environmental adaptability of the device.

[0026] 4. The double-layer baffle designed at the tail effectively prevents the abnormal temperature rise of the outer heat insulation cylinder caused by the backflow of the flame and the heat flow. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural schematic diagram of the present application;

[0028] Figure 2 is a structural schematic diagram of the front support frame in the present application;

[0029] Figure 3 is an outer end surface schematic diagram of the front support frame in the present application;

[0030] Figure 4 is an inner end surface schematic diagram of the front support frame in the present application;

[0031] Figure 5 is a structural schematic diagram of the rear support frame in the present application;

[0032] Figure 6 is an inner end surface schematic diagram of the rear support frame in the present application;

[0033] Figure 7 is a structural schematic diagram of the inner insulation cylinder in the application;

[0034] Figure 8 is a structural schematic diagram of the outer insulation cylinder in the application;

[0035] Figure 9 is a structural schematic diagram of a solid rocket engine long tail nozzle in the application. DETAILED DESCRIPTION

[0036] Example One:

[0037] Referring to Figures 1 to 5 An outer insulation device of a solid rocket engine long tail nozzle comprises a front support frame 2, a rear support frame 3, an inner insulation cylinder 4 and an outer insulation cylinder 5.

[0038] The front support frame 2 is provided with a long tail nozzle front section mounting hole, which comprises a front support frame arc surface and a rear head shell arc surface section bonding surface 2-1 and a front support frame straight cylinder section and a long tail nozzle shell straight cylinder section bonding surface 2-2, and is fixed on the outer surface of the head of the solid rocket engine rear head shell and the long tail nozzle shell 1 by adhesive; the outer side of the long tail nozzle front section mounting hole is provided with an inner insulation cylinder front end mounting groove 2-4 and an outer insulation cylinder front end mounting groove 2-3; the inner insulation cylinder front end mounting groove 2-4 and the outer insulation cylinder front end mounting groove 2-3 are both annular;

[0039] The rear support frame 3 is provided with a long tail nozzle rear section mounting hole, which comprises a rear support frame cylinder section and a long tail nozzle shell straight cylinder section bonding surface 3-1, and is fixed on the outer surface of the tail of the solid rocket engine rear head and the long tail nozzle shell 1 by adhesive; the outer side of the long tail nozzle rear section mounting hole is provided with an inner insulation cylinder rear end mounting groove 3-3 and an outer insulation cylinder rear end mounting groove 3-2; the outer side of the long tail nozzle rear section mounting hole is provided with an inner baffle 3-5 and an outer baffle 3-4 along the axial direction; the inner insulation cylinder rear end mounting groove 3-3 and the outer insulation cylinder rear end mounting groove 3-2 are both annular;

[0040] The inner heat insulation cylinder 4 is made of hard phenolic resin, and the two ends of the inner heat insulation cylinder are respectively designed with steps of 5-20 mm. The two ends of the inner heat insulation cylinder 4 are tightly connected with the inner heat insulation cylinder front end mounting groove 2-4 and the inner heat insulation cylinder rear end mounting groove 3-3 through adhesive. The outer heat insulation cylinder 5 is made of hard phenolic resin, and the two ends of the outer heat insulation cylinder are respectively designed with steps of 5-10 mm. The two ends of the outer heat insulation cylinder 5 are tightly connected with the outer heat insulation cylinder front end mounting groove 2-3 and the outer heat insulation cylinder rear end mounting groove 3-2 through adhesive. The two ends of the inner heat insulation cylinder 4 are respectively provided with an inner heat insulation cylinder and front support frame bonding surface 4-1 and an inner heat insulation cylinder and rear support frame bonding surface 4-2, which are fixed in the middle layer of the front support frame and the rear support frame through adhesive. The two ends of the outer heat insulation cylinder 5 are respectively provided with an outer heat insulation cylinder and front support frame bonding surface 5-1 and an outer heat insulation cylinder and rear support frame bonding surface 5-2, which are fixed in the outermost layer of the front support frame and the rear support frame through adhesive. The solid rocket engine long tail nozzle is located in the core layer, as shown in Figure 9

[0041] The curvature of the front support frame arc surface and the rear head shell arc surface segment bonding surface 2-1 is determined by the curvature of the outer surface of the solid rocket engine rear head shell, so as to ensure that the two can be tightly fitted. The diameter of the front support frame straight cylinder segment and the long tail nozzle shell straight cylinder segment bonding surface 2-2 is determined by the outer diameter of the solid rocket engine long tail nozzle shell, so as to ensure that the two can be tightly fitted. The diameter of the rear support frame cylinder segment and the long tail nozzle shell straight cylinder segment bonding surface 3-1 is determined by the outer diameter of the solid rocket engine long tail nozzle shell, so as to ensure that the two can be tightly fitted.

[0042] The outer heat insulation device is tightly bonded with the solid rocket engine through adhesive, and normal pressure air is filled between the inner heat insulation cylinder 4 and the solid rocket engine rear head and long tail nozzle shell 1, and normal pressure air is filled between the outer heat insulation cylinder 5 and the inner heat insulation cylinder 4.

[0043] Preferably, the inner diameter of the front part of the long tail nozzle front segment mounting hole decreases from outside to inside, and the inner diameter of the rear part of the long tail nozzle front segment mounting hole is the same.

[0044] Referring to Figure 3 , Figure 7 , the bottom of the inner heat insulation cylinder front end mounting groove 2-4 is uniformly distributed with four inner heat insulation cylinder front end arc positioning holes 2-6 in the circumferential direction, and the inner heat insulation cylinder front end is uniformly distributed with four inner heat insulation cylinder front end arc positioning inserts 4-3 in the circumferential direction. The four inner heat insulation cylinder front end arc positioning inserts 4-3 are connected with the four inner heat insulation cylinder front end arc positioning holes 2-6. The central angle corresponding to the inner heat insulation cylinder front end arc positioning insert 4-3 is 20°-60°.

[0045] Referring to Figure 3 , Figure 8 ​The bottom of the outer heat insulation cylinder front end installation groove 2-3 is circumferentially and uniformly provided with four outer heat insulation cylinder front end arc-shaped positioning holes 2-5, and the outer heat insulation cylinder front end is circumferentially and uniformly provided with four outer heat insulation cylinder front end arc-shaped positioning plug plates 5-3, and the four outer heat insulation cylinder front end arc-shaped positioning plug plates 5-3 are connected with the four outer heat insulation cylinder front end arc-shaped positioning holes 2-5. The central angle of the outer heat insulation cylinder front end arc-shaped positioning plug plate 5-3 corresponding to the circle is 20°-60°.

[0046] Preferably, the inner heat insulation cylinder front end arc-shaped positioning hole 2-6 is a through hole with a central angle of 20°-60°, and the outer heat insulation cylinder front end arc-shaped positioning hole 2-5 is a through hole with a central angle of 20°-60°. Limiting for the inner heat insulation cylinder and the outer heat insulation cylinder.

[0047] Referring to Figure 2 The front support frame is made of hard phenolic resin material, has high temperature resistance, low thermal conductivity and high strength. The outer surface of the front support frame is axially provided with an inner heat insulation cylinder front end socket and an outer heat insulation cylinder front end socket, the inner heat insulation cylinder front end installation groove 2-4 is arranged in the inner heat insulation cylinder front end socket, and the outer heat insulation cylinder front end installation groove 2-3 is arranged in the outer heat insulation cylinder front end socket. The depth of the inner heat insulation cylinder front end installation groove 2-4 and the outer heat insulation cylinder front end installation groove 2-3 is about 6-10mm.

[0048] Referring to Figure 6 , Figure 7 The bottom of the inner heat insulation cylinder rear end installation groove 3-3 is circumferentially and uniformly provided with four inner heat insulation cylinder rear end arc-shaped positioning holes 3-7, and the inner heat insulation cylinder rear end is circumferentially and uniformly provided with four inner heat insulation cylinder rear end arc-shaped positioning plug plates 4-4, and the four inner heat insulation cylinder rear end arc-shaped positioning plug plates 4-4 are connected with the four inner heat insulation cylinder rear end arc-shaped positioning holes 3-7.

[0049] Referring to Figure 6 , Figure 8 The bottom of the outer heat insulation cylinder rear end installation groove 3-2 is circumferentially and uniformly provided with four outer heat insulation cylinder rear end arc-shaped positioning holes 3-6, and the outer heat insulation cylinder rear end is circumferentially and uniformly provided with four outer heat insulation cylinder rear end arc-shaped positioning plug plates 5-4, and the four outer heat insulation cylinder rear end arc-shaped positioning plug plates 5-4 are connected with the four outer heat insulation cylinder rear end arc-shaped positioning holes 3-6.

[0050] Referring to Figure 5 The outer surface of the rear support frame is axially provided with an inner heat insulation cylinder rear end socket and an outer heat insulation cylinder rear end socket, the inner heat insulation cylinder rear end installation groove 3-3 is arranged in the inner heat insulation cylinder rear end socket, and the outer heat insulation cylinder rear end installation groove 3-2 is arranged in the outer heat insulation cylinder rear end socket. The depth of the inner heat insulation cylinder rear end installation groove 3-3 is about 10-15mm, and the depth of the outer heat insulation cylinder front end installation groove 3-2 is about 5-10mm.

[0051] Preferably, the rear end arc-shaped positioning hole 3-7 of the inner heat insulation cylinder is a blind hole with a central angle of 20°-60°, and the rear end arc-shaped positioning hole 3-6 of the outer heat insulation cylinder is a blind hole with a central angle of 20°-60°. The limiting position for the inner heat insulation cylinder and the outer heat insulation cylinder.

[0052] Preferably, the rear support frame 3 is made of hard phenolic resin, and the rear support frame is provided with an inner baffle 3-5 and an outer baffle 3-4 along the axial direction, the outer baffle is used to block the backflow of the flame and heat flow sprayed by the nozzle, and the distance between the inner baffle 3-5 and the outer baffle 3-4 is 5-20 mm, which is used to separate the high-temperature transmission of the outer baffle to the outer heat insulation cylinder 5.

[0053] The preparation method of the outer heat insulation device of the long-tail nozzle of the solid rocket engine comprises the following steps:

[0054] 1) Installation of the front support frame 2: coat adhesive on the inner and outer surfaces of the bonding surface 2-1 of the arc surface of the front support frame and the arc surface segment of the rear head shell, and coat adhesive on the inner and outer surfaces of the bonding surface 2-2 of the straight cylinder segment of the front support frame and the straight cylinder segment of the long-tail nozzle shell, then put the front support frame 2 on the solid rocket engine rear head and the long-tail nozzle shell, press tightly, rotate for more than two turns, fill the adhesive uniformly in the bonding position, clean the overflowed adhesive in time during the rotation process, and carry out the next operation after solidification and molding.

[0055] 2) Installation of the inner heat insulation cylinder 4: coat adhesive on the inner and outer surfaces of the bonding surface 4-1 of the inner heat insulation cylinder and the front support frame, put it into the groove 2-4 of the front support frame for placing the inner heat insulation cylinder, insert about 2 / 3 deep, then rotate for more than two turns, fill the adhesive uniformly in the bonding position, clean the overflowed adhesive in time during the rotation process, finally align the rear end arc-shaped positioning plug 4-4 of the inner heat insulation cylinder with the front end arc-shaped positioning hole 2-6 of the inner heat insulation cylinder, press tightly, and carry out the next operation after solidification and molding.

[0056] 3) Installation of the outer heat insulation cylinder 5: coat adhesive on the inner and outer surfaces of the bonding surface 5-1 of the outer heat insulation cylinder and the front support frame, put it into the front end mounting groove 2-3, insert about 2 / 3 deep, then rotate for more than two turns, fill the adhesive uniformly in the bonding position, clean the overflowed adhesive in time during the rotation process, finally align the front end arc-shaped positioning plug 5-3 of the outer heat insulation cylinder with the bottom of the groove of the front support frame and the front end arc-shaped positioning hole 2-5 of the outer heat insulation cylinder, press tightly, and carry out the next operation after solidification and molding.

[0057] 4) After installation, support frame 3: In the inner heat insulation cylinder and the rear support frame bonding surface 4-2, the outer heat insulation cylinder and the rear support frame bonding surface 5-2 inner and outer surface paste adhesive, the rear support frame cylinder section and the long tail nozzle shell straight section bonding surface 3-1 inner surface paste adhesive; The inner heat insulation cylinder rear end installation slot 3-3 and the outer heat insulation cylinder rear end installation slot 3-2 are inserted into the inner heat insulation cylinder 4 and the outer heat insulation cylinder 5 about 2 / 3 deep, then rotate more than two weeks, so that the adhesive is evenly filled in the bonding place, clean the overflowed adhesive in time during the rotation process, finally the inner heat insulation cylinder rear end arc positioning hole 3-7 and the outer heat insulation cylinder rear end arc positioning hole 3-6 are aligned with the inner heat insulation cylinder rear end arc positioning plug 4-4 and the outer heat insulation cylinder rear end arc positioning plug 5-4, and then the force is pressed tightly, and the long time working solid rocket engine nozzle outer heat insulation device is obtained after solidification.

[0058] Example two:

[0059] The solid rocket engine long tail nozzle of the embodiment comprises the outer heat insulation device of example one, and the outer heat insulation device is sleeved on the outer surface of the solid rocket engine long tail nozzle.

[0060] The technical content of the outer heat insulation device is understood with reference to the disclosed content of example one, and the embodiment will not be described here.

[0061] The application has been applied to multiple long time working solid rocket engines, and the heat protection effect is good. For example, the outer wall temperature of a certain type of engine can be reduced from 483 DEG C to 103 DEG C by adopting the outer heat insulation device, and the temperature is reduced by about 380 DEG C; while the conventional outer protection device of the same weight can reduce the temperature from 483 DEG C to 227 DEG C, and the temperature is reduced by about 250 DEG C; in order to achieve the same protection effect, the weight of the conventional outer protection device will increase by about 160%; it is shown that the outer heat insulation device has smaller negative mass and better heat insulation performance.

[0062]

[0063]

[0064] In summary, the beneficial effects of the application are:

[0065] 1) The material adopted in the application has simple structure and is easy to obtain, the material has the characteristics of high temperature resistance, low thermal conductivity and high strength, and the whole preparation process does not involve complex process steps, and the yield is high.

[0066] 2) The application internally adopts air for heat insulation, which not only reduces the mass of the device, but also has good heat insulation performance.

[0067] 3) The application designs a sector hole on the support frame, which effectively ensures the axial positioning of the inner and outer heat insulation cylinders, and further enhances the environmental adaptability of the device.

[0068] 4) The invention is designed with double-layer baffle at the tail, which effectively prevents the abnormal temperature rise of the outer insulation cylinder caused by the backflow of flame and heat flow.

Claims

1. An external heat insulation device for the long tail nozzle of a solid rocket motor, characterized in that: Includes front support frame, rear support frame, inner insulation cylinder and outer insulation cylinder; The front support frame is provided with a mounting hole for the front section of the long tail nozzle, and the outer side of the mounting hole for the front section of the long tail nozzle is provided with a mounting groove for the front end of the inner insulation cylinder and a mounting groove for the front end of the outer insulation cylinder. The rear support frame is provided with a mounting hole for the rear section of the long tail nozzle. The outer side of the mounting hole for the rear section of the long tail nozzle is provided with a mounting groove for the rear end of the inner insulation cylinder and a mounting groove for the rear end of the outer insulation cylinder. An inner baffle and an outer baffle are provided along the axial direction on the outer side of the mounting hole for the rear section of the long tail nozzle. The two ends of the inner heat insulation cylinder are respectively connected to the front mounting groove of the inner heat insulation cylinder and the rear mounting groove of the inner heat insulation cylinder; the two ends of the outer heat insulation cylinder are respectively connected to the front mounting groove of the outer heat insulation cylinder and the rear mounting groove of the outer heat insulation cylinder; atmospheric pressure air is filled between the inner heat insulation cylinder and the rear end cap and long tail nozzle shell of the solid rocket motor, and atmospheric pressure air is filled between the outer heat insulation cylinder and the inner heat insulation cylinder.

2. The external insulation device according to claim 1, characterized in that: The inner diameter of the front part of the mounting hole of the long tail nozzle decreases from the outside to the inside, while the inner diameter of the rear part of the mounting hole of the long tail nozzle remains the same.

3. The external insulation device according to claim 1, characterized in that: The bottom of the mounting groove at the front end of the inner insulation cylinder has a plurality of arc-shaped positioning holes at the front end of the inner insulation cylinder evenly distributed along the circumference. The front end of the inner insulation cylinder has a plurality of arc-shaped positioning plates evenly distributed along the circumference. The plurality of arc-shaped positioning plates at the front end of the inner insulation cylinder are connected to the plurality of arc-shaped positioning holes at the front end of the inner insulation cylinder.

4. The external insulation device according to claim 3, characterized in that: The bottom of the mounting groove at the front end of the external insulation cylinder has a plurality of arc-shaped positioning holes at the front end of the external insulation cylinder evenly distributed along the circumference. The front end of the external insulation cylinder has a plurality of arc-shaped positioning plates evenly distributed along the circumference. The plurality of arc-shaped positioning plates at the front end of the external insulation cylinder are connected to the plurality of arc-shaped positioning holes at the front end of the external insulation cylinder.

5. The external insulation device according to claim 4, characterized in that: The arc-shaped positioning hole at the front end of the inner insulation cylinder is a through hole, and the arc-shaped positioning hole at the front end of the outer insulation cylinder is a through hole.

6. The external insulation device according to claim 3 or 4, characterized in that: The outer surface of the front support frame is provided with an inner insulation cylinder front end socket and an outer insulation cylinder front end socket along the axial direction. The inner insulation cylinder front end mounting groove is disposed in the inner insulation cylinder front end socket, and the outer insulation cylinder front end mounting groove is disposed in the outer insulation cylinder front end socket.

7. The external insulation device according to claim 1, characterized in that: The bottom of the mounting groove at the rear end of the inner insulation cylinder has a plurality of arc-shaped positioning holes at the rear end of the inner insulation cylinder evenly distributed along the circumference. The rear end of the inner insulation cylinder has a plurality of arc-shaped positioning plates evenly distributed along the circumference. The plurality of arc-shaped positioning plates at the rear end of the inner insulation cylinder are connected to the plurality of arc-shaped positioning holes at the rear end of the inner insulation cylinder.

8. The external insulation device according to claim 7, characterized in that: The bottom of the mounting groove at the rear end of the external insulation cylinder has a plurality of arc-shaped positioning holes at the rear end of the external insulation cylinder evenly distributed along the circumference. The rear end of the external insulation cylinder has a plurality of arc-shaped positioning plates evenly distributed along the circumference. The plurality of arc-shaped positioning plates at the rear end of the external insulation cylinder are connected to the plurality of arc-shaped positioning holes at the rear end of the external insulation cylinder.

9. The external insulation device according to claim 7 or 8, characterized in that: The outer surface of the rear support frame is provided with an inner insulation cylinder rear end socket and an outer insulation cylinder rear end socket along the axial direction. The inner insulation cylinder rear end mounting groove is disposed in the inner insulation cylinder rear end socket, and the outer insulation cylinder rear end mounting groove is disposed in the outer insulation cylinder rear end socket.

10. The external insulation device according to claim 8, characterized in that: The arc-shaped positioning hole at the rear end of the inner insulation cylinder is a blind hole, and the arc-shaped positioning hole at the rear end of the outer insulation cylinder is a blind hole.

11. The external insulation device according to claim 1, characterized in that: The distance between the inner baffle and the outer baffle is 5 to 20 mm.

12. A long tail nozzle for a solid rocket motor, characterized in that: Includes the external heat insulation device as described in any one of claims 1-11, wherein the external heat insulation device is fitted onto the outer surface of the long tail nozzle of a solid rocket motor.

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