A lightweight porous media sandwich structure for permeable nozzles

Abstract

The application discloses a light porous medium sandwich structure for a permeable nozzle, and belongs to the field of aerospace technology. The structure can keep the temperature of the porous medium material at the permeable section at a safe level, and ensure the structural integrity of the permeable nozzle. An embedded cold water pipe is arranged in the light porous medium sandwich and the structure of the nozzle base section. The outer surface of the porous medium sandwich is a sheet type carbon-carbon composite material, and the material is provided with uniformly distributed air holes with small diameters, which can ensure the structural strength, the air permeability of the permeable section, the thrust compensation effect of the permeable nozzle, and the like. The ring pipeline formed by multiple circular loops in the application can effectively provide a heat exchange area, and the existence of the wetting water holes enables the coolant to wet the porous medium. The open circulation flow of the coolant can continuously cool the permeable section, effectively inhibit the temperature rise of the porous medium material in the high-altitude working environment, and improve the working stability of the nozzle and prolong the service life of the nozzle.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology, specifically relating to a lightweight porous media sandwich structure for permeable nozzles. Background Technology

[0002] To improve the overall ballistic thrust performance of engines, height-compensating nozzles have been extensively studied. The permeable height-compensating nozzle (hereinafter referred to as the permeable nozzle) is a new type of height-compensating nozzle. It has the same profile as traditional nozzles, but its expansion section consists of a base section and a permeable nozzle. The base section has the same structure as a traditional bell-shaped nozzle, while the permeable section uses a perforated plate material or a porous medium material. Permeable nozzles have advantages such as continuous profile, high reliability, simple structure, no need for mechanical devices, and continuous compensation. However, under high-altitude conditions, a small amount of exhaust gas may leak from the permeable section, causing the wall temperature of the permeable section to reach approximately 3000K. If the permeable section uses a perforated plate structure, i.e., densely packed small-diameter holes are drilled into the metal wall, the heat resistance of the permeable section is better in this case. When the permeable section uses a porous medium, there are more serious thermal protection problems. With current technology, the porous media material in the permeable section can be made of ceramic or metal materials. These materials are prone to oxidation or melting at high temperatures of 3000K, which damages the pore structure of the porous media and reduces the performance of the permeable nozzle. Summary of the Invention

[0003] This invention provides a lightweight porous media sandwich structure for permeable nozzles, which solves the thermal protection problem of permeable nozzles, keeps the temperature of the porous media material at a safe level, and ensures the structural integrity of the permeable nozzle.

[0004] The technical solution adopted in this invention is:

[0005] A lightweight porous media sandwich structure for a permeable nozzle includes a base section, a permeable section, and an embedded cold water pipe; the permeable section adopts a lightweight porous media sandwich structure with multiple vent holes on its surface, and the embedded cold water pipe is disposed within the lightweight porous media and the inner wall of the base section.

[0006] Compared with the prior art, the present invention has the following advantages:

[0007] 1. The present invention uses carbon-carbon composite material as the nozzle shell, which can significantly reduce weight while ensuring the structural strength of the nozzle wall;

[0008] 2. The outer surface of the porous media interlayer of the present invention is a thin sheet carbon-carbon composite material with uniformly distributed, small-diameter vent holes. This ensures the structural lightness without affecting the air permeable section and guarantees the thrust compensation effect of the permeable nozzle.

[0009] 3. The surrounding pipeline composed of multiple circular loops in this invention can effectively provide a certain heat exchange area. The presence of wetting water holes allows the coolant to wet the porous medium. The open circulation of the coolant can continuously cool the permeable section, effectively suppressing the temperature rise of the porous medium material in the high-altitude working environment.

[0010] 4. This invention can solve the problem of high-altitude overheating in the permeable section of a permeable nozzle, improve the working stability of the nozzle, and extend the service life of the permeable section. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0012] Figure 2 This is a schematic diagram of the embedded cold water pipe structure of the present invention;

[0013] Figure 3 This is a detailed diagram of the surrounding pipeline of the embedded cold water pipe of the present invention;

[0014] Figure 4 This is a cross-sectional view of the lightweight porous media sandwich structure of the present invention;

[0015] The components include: 1. base section; 2. permeable section; 3. inlet pipe; 4. surrounding pipe; 5. immersion water hole; 6. outlet pipe; 7. vent hole; 8. porous medium; and 9. carbon-carbon composite material shell. Detailed Implementation

[0016] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings.

[0017] In this embodiment, the permeable nozzle is only a schematic diagram. The length of the permeable section is determined based on the actual engine combustion chamber parameters and the engine's flight altitude. For ease of description, all solid walls of the nozzle are defined as the basic section, and the portion that allows airflow between the inside and outside of the wall is defined as the permeable section.

[0018] according to Figure 1 The overall structure of the permeable nozzle is divided into a basic section 1 and a permeable section 2.

[0019] The section with multiple vent holes 7 is the permeable section 2. The diameter of the vent holes 7 is in the range of 0.25 mm to 1 mm, and the porosity is in the range of 0.1 to 0.2.

[0020] The permeable section 2 adopts a lightweight porous media sandwich structure, and the embedded cold water pipe is installed in the lightweight porous media sandwich and in the inner wall of the foundation section 1.

[0021] The embedded cold water pipe located within the permeable section 2 has uniformly distributed wetting water holes 5. Some of the coolant inside the embedded cold water pipe can enter the lightweight porous medium interlayer through the wetting water holes 5, wetting the porous medium and improving the cooling efficiency through heat conduction and evaporation mechanisms.

[0022] The specific structure of the embedded cold water pipe is as follows: it includes an inlet pipe 3, an outlet pipe 6, and a surrounding pipe 4; the inlet pipe 3 and the outlet pipe 6 are embedded inside the wall of the foundation section 1 and in the lightweight porous medium interlayer of the permeable section 2. The inlet pipe 3 and the outlet pipe 6 extend along the spray pipe axis. The surrounding pipe 4 is composed of multiple circular loops and is embedded in the lightweight porous medium interlayer of the permeable section 2 in the circumferential direction. The multiple circular loops are connected to the inlet pipe 3 and the outlet pipe 6 respectively. Wetting holes 5 are evenly distributed on the surrounding pipe 4.

[0023] The diameter of the water immersion hole 5 is smaller than the diameter of the vent hole 7.

[0024] The permeable section 2 has a "sandwich" structure. The upper and lower layers of this structure are carbon-carbon composite material shells 9 with distributed vents, and the middle layer consists of a porous medium 8 containing an embedded cold water pipe. Each layer is 5 mm thick.

[0025] The distribution of the vent 7 is staggered from the distribution of the surrounding pipe 4.

[0026] The lightweight porous media sandwich structure used in permeable nozzles achieves the purpose of cooling the permeable section through the following steps:

[0027] When the engine's flight altitude rises to a certain level, the ambient pressure begins to be lower than the pressure on the inner wall of the permeable section of the nozzle. As a result, the combustion gases inside the nozzle will leak from the permeable section to the outside, causing the temperature in the permeable section, especially in the lightweight porous media interlayer, to rise.

[0028] When the gas inside the nozzle begins to leak, the coolant in the embedded cold water pipe begins to flow, circulating openly along the inlet pipe 3, the surrounding pipe 4, and the outlet pipe 6. The coolant, at a lower temperature, reaches the surrounding pipe 4 located inside the permeable section 2 via the inlet pipe. There, it absorbs heat through heat conduction with the high-temperature permeable section structure, cooling the porous media material surrounding the cold water pipe and consequently lowering the overall temperature of the porous media material. This prevents damage to the porous media material due to high temperatures and ensures the structural integrity of the permeable nozzle. As the coolant flows within the surrounding pipe 4, in addition to heat conduction with the high-temperature wall surface, some coolant enters the porous media through the wetting holes 5, wetting the porous media and enhancing its cooling efficiency through heat conduction and evaporation. This wetting behavior makes the coolant flow system an open circulation system. The remaining coolant in the surrounding pipe 4 leaves the high-temperature permeable section 2 through the outlet pipe 6, and after being cooled, it re-enters the surrounding pipe 4 along the inlet pipe 3 to further reduce the temperature of the permeable section 2, thus achieving open circulation flow in a continuous cycle.

[0029] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A lightweight porous media sandwich structure for permeable nozzles, characterized in that: It includes a base section (1), a permeable section (2), and an embedded cold water pipe; the permeable section (2) adopts a lightweight porous medium sandwich structure with multiple vent holes (7) on its surface. The embedded cold water pipe is set inside the lightweight porous medium (8) and inside the inner wall of the base section (1). Wetting water holes (5) are evenly distributed on the embedded cold water pipe located in the permeable section (2). Some of the coolant in the embedded cold water pipe can enter the lightweight porous medium sandwich through the wetting water holes (5).

2. The lightweight porous media sandwich structure for a permeable nozzle according to claim 1, characterized in that: The diameter of the vent (7) is in the range of 0.25 mm to 1 mm, and the porosity is in the range of 0.1 to 0.

2.

3. The lightweight porous media sandwich structure for a permeable nozzle according to claim 1, characterized in that: The embedded cold water pipe includes an inlet pipe (3), an outlet pipe (6), and a surrounding pipe (4). The inlet pipe (3) and the outlet pipe (6) are embedded inside the wall of the foundation section (1) and in the lightweight porous medium interlayer of the permeable section (2). The inlet pipe (3) and the outlet pipe (6) extend along the axial direction of the nozzle. The surrounding pipe (4) is composed of multiple circular loops and is embedded in the lightweight porous medium interlayer of the permeable section (2) in the circumferential direction. The multiple circular loops are connected to the inlet pipe (3) and the outlet pipe (6) respectively. Wetting holes (5) are evenly distributed on the surrounding pipe (4).

4. A lightweight porous media sandwich structure for a permeable nozzle according to claim 3, characterized in that: The diameter of the immersion water hole (5) is smaller than the diameter of the vent hole (7).

5. A lightweight porous media sandwich structure for a permeable nozzle according to claim 4, characterized in that: The upper and lower layers of the lightweight porous media sandwich structure of the permeable section (2) are carbon composite material shells (9), and the middle layer is composed of porous media (8) containing an embedded cold water pipe.

6. A lightweight porous media sandwich structure for a permeable nozzle according to claim 4, characterized in that: The distribution of the vent holes (7) is staggered from the distribution of the surrounding pipes (4).

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