Heat exchange device for sub-orbital aircraft load under dynamic acceleration condition

Abstract

The invention belongs to the technical field of space flight and aviation heat dissipation, and particularly relates to a heat exchange device for a sub-orbital aircraft load under a dynamic acceleration condition, which comprises a flexible heat pipe, an evaporation section of the flexible heat pipe is coupled with a packaging structure of a heat source through a high heat conduction fixing piece, and a condensation section of the flexible heat pipe is connected with a sliding device through a heat insulation fixing piece; the flexible heat pipe is filled with working fluid. The sliding device is in sliding connection with the bottom wall of the cylindrical shell, responds to centrifugal force generated by dynamic acceleration of the aircraft and drives the condensation section of the flexible heat pipe to move to the position opposite to the acceleration direction along the bottom wall of the cylindrical shell; through the combination of the sliding device and the flexible heat pipe, the condensation section is driven by centrifugal force to move to the bottom in the acceleration direction, a high-temperature area is formed, the temperature layout in the cylindrical shell is actively optimized, the circulation efficiency of hot air rising and cold air sinking is remarkably improved, and the traditional natural convection efficiency bottleneck is broken through; and an innovative solution is provided for thermal management of the spacecraft under the high-dynamic working condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace heat dissipation, and particularly relates to a device for enhancing natural convection heat transfer of a suborbital vehicle payload under dynamic acceleration conditions, and is particularly applicable to scenarios where the heat source position is adaptively adjusted to optimize the temperature gradient distribution and improve the natural convection heat dissipation efficiency. Background Art

[0002] A suborbital vehicle refers to a vehicle that enters space (usually referring to the Karman line with a height exceeding 100 kilometers), but does not enter a stable orbit around the Earth. It usually flies along a parabolic or elliptical orbit, with the highest point outside the atmosphere, but the trajectory will eventually return to the ground; its motion is divided into the following stages: during the ascent stage, it is launched by a rocket or booster, and the speed increases rapidly and rises into space; during the brief weightless state, due to the free-fall characteristics of the trajectory, at the flight apex, the spacecraft interior will experience a microgravity environment for several minutes; when returning to the atmosphere, since it does not reach orbital speed, the vehicle will re-enter the atmosphere along a ballistic trajectory and eventually land.

[0003] Due to the high-speed re-entry into the atmosphere, the aerodynamic heating of a suborbital vehicle increases sharply, and the air is compressed to form a shock wave, resulting in an increase in heat transfer. The temperature of the outer surface of the payload compartment can reach 1000°C to 2000°C. The main thermal challenges are external high-temperature protection and internal temperature control; to resist external high temperatures, the outside of the suborbital vehicle uses heat-insulating materials, transpiration cooling, etc. to dissipate heat; this results in the payload compartment inside usually being a closed space, lacking active heat dissipation resources, and often relying only on natural heat dissipation, and it is desired that this natural heat dissipation can make the temperature inside the compartment as uniform as possible, that is, the temperature difference between the central heat source and the payload compartment wall and inside the payload compartment is reduced to prevent structural damage and ensure that the payload and personnel are not affected by extreme temperatures.

[0004] That is, in the existing aircraft structure, the payload compartment lacks an active heat dissipation device and only relies on natural air circulation, which will lead to uneven temperature distribution, too large a temperature difference between the central heat source and the payload compartment wall, and easily increase the risk of payload instability or even damage.

[0005] Just under such a background, the present invention proposes a heat exchange device for a suborbital vehicle payload under dynamic acceleration conditions, which can optimize the heat source distribution under dynamic acceleration conditions, maintain a temperature difference layout conducive to natural convection, significantly improve the heat dissipation efficiency, reduce the maximum temperature difference, and make the temperature distribution uniform, and has important engineering application value. Summary of the Invention

[0006] The present invention aims to provide a heat transfer device for suborbital vehicle payloads that enhances natural convection heat transfer. Through the synergistic effect of flexible heat pipes and sliding devices, the position of the condensation section is adaptively adjusted under dynamic acceleration conditions to reconstruct the temperature gradient and flow field distribution, significantly reducing the maximum temperature difference and improving the heat dissipation efficiency. The specific technical solution is as follows:

[0007] The present invention provides a heat transfer device for suborbital vehicle payloads under dynamic acceleration conditions, comprising:

[0008] A flexible heat pipe, the evaporation section of which is coupled to the encapsulation structure of the heat source through a high thermal conductivity fixing member, and the condensation section is connected to the sliding device through a heat insulation fixing member, and the interior of the flexible heat pipe is filled with a working fluid;

[0009] A sliding device, which is slidably connected to the bottom wall of the cylindrical shell, and in response to the centrifugal force generated by the dynamic acceleration of the vehicle, drives the condensation section of the flexible heat pipe to move along the bottom wall of the cylindrical shell to a position opposite to the acceleration direction;

[0010] A convection enhancement structure, comprising a connecting member and a cylindrical shell, the connecting member connecting the encapsulation structure of the heat source and the cylindrical shell and forming an air circulation channel;

[0011] Wherein, the condensation section of the flexible heat pipe forms a high-temperature region under dynamic acceleration, and by reconstructing the temperature gradient and flow field distribution inside the cylindrical shell, the natural convection heat transfer efficiency of the heat source is enhanced.

[0012] In an alternative embodiment, a capillary structure is provided inside the tube wall of the flexible heat pipe.

[0013] In an alternative embodiment, the capillary structure includes any one of a fiber mesh structure, a porous material structure, a thin film capillary structure, a spiral tube type capillary structure, a carbon nanotube or a nanofiber capillary structure.

[0014] In an alternative embodiment, the working fluid is liquid ammonia with a purity of 99.999%.

[0015] In an alternative embodiment, the sliding device includes a chute and a slider;

[0016] The chute is opened on the bottom wall of the cylindrical shell;

[0017] One end of the slider is engaged in the chute, and the other end is fixedly connected to the condensation section of the flexible heat pipe through a heat insulation fixing member.

[0018] In an alternative embodiment, the opening path of the chute includes one of opening along the radial direction of the bottom wall of the cylindrical shell, opening along the circumferential direction of the bottom wall of the cylindrical shell, opening in a random shape along the bottom wall of the cylindrical shell, or a combination of one or more of these opening methods.

[0019] In an optional embodiment, the high thermal conductivity fixing member is a copper gasket, and the thermal insulation fixing member is a gasket made of ceramic fiber.

[0020] In an optional embodiment, the packaging structure of the cylindrical shell and the heat source are both split structures, and the cylindrical shell is locked by a lock after being combined.

[0021] In an optional embodiment, the connecting member includes a connecting plate and / or a connecting rod.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention combines a sliding device with a flexible heat pipe, utilizes centrifugal force to drive the condensation section to move to the bottom in the acceleration direction, forms a high-temperature area, and actively optimizes the temperature layout in the cylindrical shell. This dynamic adaptive adjustment ensures that the heat source is always located at the bottom which is conducive to natural convection, significantly enhances the circulation efficiency of hot air rising and cold air sinking, and reduces the maximum temperature difference around the heat source from 27.3°C to 24.8°C, a decrease of 9.16%. It combines the passive heat transfer of the flexible heat pipe with the active adjustment of the sliding device, optimizes the temperature field and flow field distribution in real time, breaks through the bottleneck of traditional natural convection efficiency, and provides an innovative solution for spacecraft thermal management under high dynamic conditions, solving the heat dissipation problem of suborbital spacecraft under drastic acceleration changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is an oblique isometric cross-sectional view of the heat exchange device of the present invention;

[0026] Figure 2 It is a cross-sectional view of the heat exchange device of the present invention;

[0027] Figure 3 This is a schematic diagram of the split-type opening and closing structure of the heat exchange device of the present invention;

[0028] Figure 4 This is a schematic diagram of the heat exchange process of the flexible heat pipe of the present invention;

[0029] Figure 5 Comparison of temperature cloud diagrams with and without flexible heat pipes under the same heat source conditions;

[0030] Figure 6 Comparison of velocity contour maps with and without a flexible heat pipe under the same heat source conditions;

[0031] Figure 7 Comparison of pressure contour maps with and without a flexible heat pipe under the same heat source conditions;

[0032] In the figure: 1. Flexible heat pipe; 2. Encapsulation structure; 3. High - thermal - conductivity fixing part; 4. Heat - insulation fixing part; 501. Slide groove; 502. Slide block; 6. Cylindrical shell; 7. Capillary structure; 8. Lock; 9. Connecting piece; 10. Hinge. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Please refer to Figures 1-7 As shown, in this embodiment, the present invention provides a heat - exchange device for a sub - orbital vehicle payload under dynamic acceleration conditions, including: a flexible heat pipe 1, whose evaporation section is coupled with the encapsulation structure 2 of the heat source through a high - thermal - conductivity fixing part 3, and the condensation section is connected to a sliding device through a heat - insulation fixing part 4, and the interior of the flexible heat pipe 1 is filled with a working fluid; a sliding device, which is slidably connected to the bottom wall of the cylindrical shell 6, responds to the centrifugal force generated by the dynamic acceleration of the vehicle, and drives the condensation section of the flexible heat pipe 1 to move along the bottom wall of the cylindrical shell 6 to a position opposite to the acceleration direction; a convective - enhancement structure, including a connecting piece 9 and a cylindrical shell 6, the connecting piece 9 connects the encapsulation structure 2 of the heat source and the cylindrical shell 6, and forms an air - circulation channel; wherein, the condensation section of the flexible heat pipe 1 forms a high - temperature region under dynamic acceleration, and by reconstructing the temperature gradient and flow - field distribution in the cylindrical shell 6, the natural - convection heat - exchange efficiency of the heat source is enhanced.

[0035] Inside the payload compartment of the vehicle, scientific instruments, communication equipment, weapon systems, cargo, or other mission - critical components are encapsulated using the encapsulation structure 2. These components generate heat during use or transportation during flight due to vibration or power consumption, such as power amplifiers, microwave / millimeter - wave power devices, etc. Especially under harsh conditions of high temperature and lack of active heat - dissipation resources, the above - mentioned components can far from meet the heat - dissipation requirements only through the natural - convection mechanism, and it is easy to cause component damage or failure due to insufficient heat - dissipation capacity and heat accumulation.

[0036] Specifically, in this embodiment, the encapsulation structure 2 encapsulating the heat source is erected and fixed in the middle of the cylindrical shell 6 by the connecting member 9 from above, and the cylindrical shell 6 can be fixed in the exact middle of the aircraft payload bay. Among them, for the convenience of payload encapsulation, the entire encapsulation structure 2 and the cylindrical shell 6 can be designed in a split type. As Figure 3 shown, two split-designed cylindrical shells 6 can be rotatably connected together by welding hinges 10 on both sides of the cylindrical shell 6, and the split-designed encapsulation structure 2 is also fixed inside the cylindrical shell 6 by the connecting member 9 through welding. Therefore, when the cylindrical shell 6 is rotated and opened with the hinge 10 as the center, the inside of the encapsulation structure 2 will also be exposed. At this time, it is convenient to load the payload devices that need to be transported or carried into the encapsulation structure 2. After loading, rotate the cylindrical shell 6 in the reverse direction, and use the lock 8 welded to the opening and closing side of the cylindrical shell 6 to fix and lock the two cylindrical shells 6. At this time, the encapsulation structure 2 inside the cylindrical shell 6 will also close with the closing of the cylindrical shell 6, thus completing the payload encapsulation.

[0037] As Figures 1 to 3 shown, in order to facilitate the flow of air on the surface of the encapsulation structure 2 and improve the heat exchange efficiency between the encapsulation structure 2 and the air inside the cylindrical shell 6, the encapsulation structure 2 can be designed as a spherical shape, so that the air can flow more smoothly along the surface of the encapsulation structure 2. At the same time, in order to ensure the smooth flow of air inside the cylindrical shell 6, when the encapsulation structure 2 is fixedly installed inside the cylindrical shell 6 by the connecting member 9, there should be enough gaps between the connecting members 9 to form an air circulation channel with enough space for air to freely flow, and try to avoid installing the connecting member 9 below the encapsulation structure 2, so as to avoid interfering with the movement of the flexible heat pipe 1 below the encapsulation structure 2 and make the heat exchange space below the encapsulation structure 2 spacious and unobstructed. Specifically, the connecting member 9 can be plate-shaped or rod-shaped.

[0038] Furthermore, the two ends of the flexible heat pipe 1 are respectively connected to the encapsulation structure 2 and the sliding device, and during the heat dissipation process, the condensation section of the flexible heat pipe 1 needs to swing in response to the direction of the aircraft acceleration. Therefore, the installation stability of the flexible heat pipe 1 is also one of the important considerations. Optionally, the evaporation section of the flexible heat pipe 1 is welded to the lower end surface of the encapsulation structure 2 through a highly thermally conductive fixing member 3, and the condensation section of the flexible heat pipe 1 is glued to the sliding device through a heat-insulating fixing member 4. Among them, the highly thermally conductive fixing member 3 can be a copper gasket, and the heat of the encapsulation structure 2 is quickly transferred to the evaporation section of the flexible heat pipe 1 by using the high thermal conductivity of metallic copper. In addition, the heat-insulating fixing member 4 can be a gasket made of ceramic fiber to utilize the heat insulation ability of ceramic fiber to prevent the heat in the flexible heat pipe 1 from being transferred to the cylindrical shell 6 through the sliding device.

[0039] Furthermore, to ensure the efficiency of the internal heat convection in the cylindrical shell 6, the condensation section of the flexible heat pipe 1 needs to be restricted to the bottom wall of the cylindrical shell 6 to prevent the condensation section from moving into the hot air area, which would weaken the heat dissipation capacity of the flexible heat pipe 1. Optionally, the sliding device includes a chute 501 and a slider 502; the chute 501 and the slider 502 can be engaged through a special-shaped structure. For example, the cross-section of the slider 502 is designed as a T shape to ensure that the slider 502 can slide freely along the chute 501 while preventing the slider 502 from disengaging from the chute 501, thereby keeping the condensation section of the flexible heat pipe 1 always restricted to the bottom wall of the cylindrical shell 6.

[0040] Optionally, the opening path of the chute 501 is not unique. It can be a straight line opened along the radial direction of the bottom wall of the cylindrical shell 6, a circular ring opened along the circumferential direction of the bottom wall of the cylindrical shell 6, or a random shape, or even a combination of the above opening paths, as long as it ensures that the slider 502 can slide smoothly in the chute 501 in response to the acceleration of the aircraft. In this embodiment, a simulation experiment is conducted with the opening path of the chute 501 being a straight line opened along the radial direction of the bottom wall of the cylindrical shell 6 as an example.

[0041] The flexible heat pipe 1 can be a common stainless steel bellows, which belongs to the prior art. The specific structure and working principle will not be elaborated here. To ensure the working fluid in the flexible heat pipe 1 can flow smoothly between the condensation section and the evaporation section, a capillary structure 7 is also provided inside the pipe wall of the flexible heat pipe 1 to utilize the capillary phenomenon to achieve the transfer of the working fluid. Optionally, the working fluid can be liquid ammonia with a purity of 99.999%.

[0042] The heat source is located in the middle of the cylindrical shell 6. It is difficult for the cold wall surface of the bottom space of the cylindrical shell 6 to contact hot air, so the space utilization rate at the bottom is insufficient. Under low Rayleigh number conditions, hot air only needs a relatively small cold wall surface area to be completely cooled, so the phenomenon of low space utilization rate at the bottom is more obvious. Arranging the condensation section of a flexible heat pipe 1 at the lower end of the open space, the heat of the main heat source is transferred to its condensation section through the action of the flexible heat pipe 1, which can generate a new vortex, thus enhancing natural convection. When the magnitude and direction of the acceleration of the aircraft change, due to the existence of the sliding pair in the sliding device, the condensation section of the flexible heat pipe 1 can always remain at the corresponding bottom position. At the same time, arranging the evaporation section of a flexible heat pipe 1 near the heat source can break the thermal boundary layer near the heat source, thereby changing the flow pattern and enhancing heat transfer.

[0043] Specifically, when the aircraft is accelerating in a certain direction during flight, the generated acceleration will cause the condensation section of the flexible heat pipe 1 to move along the bottom wall chute 501 of the slider 502 in the sliding device to a position opposite to the acceleration. At this time, the heat generated by the heat source in the encapsulation structure 2 will be sequentially transferred to the encapsulation structure 2, the high thermal conductivity fixing member 3, and the evaporation section of the flexible heat pipe 1 through heat transfer; the working fluid in the flexible heat pipe 1 can absorb heat from the evaporation section, and the working fluid after absorbing heat will heat up and evaporate, and diffuse to the relatively lower temperature condensation section under a small pressure difference to release latent heat and condense into a liquid state, and the released heat will be dissipated to the outside through the tube wall of the flexible heat pipe 1; the liquid working fluid will flow towards the evaporation section of the flexible heat pipe 1 under the action of the capillary structure 7 to absorb heat again, thereby realizing further heat dissipation of the heat source. In addition, after the heat is transported to the condensation section through the flexible heat pipe 1, a new vortex will be formed in the condensation section to promote air circulation and strengthen natural convection.

[0044] Please refer to Figures 5-7 the simulation data shown below:

[0045] Among them, in state 1, there is no flexible heat pipe 1 and the acceleration direction is vertically downward;

[0046] in state 2, there is a flexible heat pipe 1 and the acceleration direction is vertically downward;

[0047] in state 3, there is a heat pipe but the heat pipe is a rigid heat pipe, the length direction of the heat pipe is perpendicular to the bottom wall of the cylindrical shell 6 and the acceleration direction is 45° obliquely downward to the right;

[0048] in state 4, there is a flexible heat pipe 1 and the acceleration direction is 45° obliquely downward to the right.

[0049] Combined with Figures 5-7 the simulation results, it can be known that the highest temperatures on the outer surface of the encapsulation structure 2 in states 1, 2, 3, and 4 are 500.4K, 499.0K, 499.1K, and 497.9K respectively, and the maximum temperature differences ∆T max are 27.3°C, 25.9°C, 26.0°C, and 24.8°C respectively. From this, we can draw the following conclusions:

[0050] First, in the case of having a heat pipe under the same acceleration direction, the highest temperature is the lowest;

[0051] Second, when the acceleration direction changes, for the flexible heat pipe 1 whose condensation section position can change with the acceleration direction compared with the rigid heat pipe with a fixed condensation section, its highest temperature is lower;

[0052] Third, when under the conditions of the same acceleration direction and magnitude, increasing the heat pipe can reduce the maximum temperature difference by 5.13%, and increasing the flexible heat pipe 1 can reduce the maximum temperature difference by 9.16%;

[0053] Combined with the temperature contour and velocity contour, it can be seen that in the embodiment of adding the flexible heat pipe 1 according to the present invention, the highest temperature is the lowest, the convection range is the widest, and the maximum temperature difference ∆T max is the smallest.

[0054] Therefore, the simulation data and the above structural mechanism analysis jointly prove that the present invention can significantly improve the heat dissipation efficiency of the load and reduce the maximum temperature difference around the load by using the dynamic acceleration condition under the harsh heat dissipation conditions where the load is at a high temperature and lacks active heat dissipation resources, which has positive significance and engineering application value for the stability of the load state.

[0055] In addition, it is worth noting that obvious temperature gradient differences and non-uniform distribution characteristics of the velocity vector field can be observed in the area near the condensation section of the flexible heat pipe 1. This indicates that the heat transfer mechanism in this area has gradually changed to convective heat transfer, reflecting a significant increase in the convective motion intensity of the fluid in the cylindrical shell 6. Through vortex dynamics analysis, it can be known that this flow field reconstruction phenomenon effectively promotes the development and update of the thermal boundary layer. In particular, the newly generated vortex structure can effectively enhance the heat exchange efficiency in the area of the cylindrical shell 6, thereby improving the heat transfer performance of the present invention as a whole, reducing the maximum temperature difference, and achieving the core goal of a uniform temperature field.

[0056] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A heat exchange device for a suborbital vehicle payload under dynamic acceleration conditions, characterized in that Comprising: A flexible heat pipe (1), whose evaporation section is coupled with the encapsulation structure (2) of the heat source through a highly thermally conductive fixing member (3), and the condensation section is connected to the sliding device through a heat-insulating fixing member (4), and the interior of the flexible heat pipe (1) is filled with a working fluid; A sliding device, which is slidably connected to the bottom wall of the cylindrical housing (6), and in response to the centrifugal force generated by the dynamic acceleration of the aircraft, drives the condensation section of the flexible heat pipe (1) to move along the bottom wall of the cylindrical housing (6) to a position opposite to the acceleration direction; A convective enhancement structure, including a connecting member (9) and a cylindrical housing (6), the connecting member (9) connects the encapsulation structure (2) of the heat source and the cylindrical housing (6), and forms an air circulation channel; Wherein, the condensation section of the flexible heat pipe (1) forms a high-temperature region under dynamic acceleration, and by reconstructing the temperature gradient and flow field distribution in the cylindrical housing (6), the natural convective heat transfer efficiency of the heat source is enhanced.

2. The heat exchange device for a suborbital vehicle payload under dynamic acceleration conditions according to claim 1, characterized in that: A capillary structure (7) is provided inside the tube wall of the flexible heat pipe (1).

3. The heat exchange device for the payload of a suborbital vehicle under dynamic acceleration conditions according to claim 2, characterized in that: The capillary structure (7) includes any one of a fiber mesh structure, a porous material structure, a thin-film capillary structure (7), a spiral tube type capillary structure (7), a carbon nanotube or nanofiber capillary structure (7).

4. The heat exchange device for a suborbital vehicle payload under dynamic acceleration conditions according to claim 1, characterized in that: The working fluid is liquid ammonia with a purity of 99.999%.

5. The heat exchange device for the payload of a suborbital vehicle under dynamic acceleration conditions according to claim 1, characterized in that: The sliding device includes a chute (501) and a slider (502); The chute (501) is opened on the bottom wall of the cylindrical housing (6); One end of the slider (502) is engaged in the chute (501), and the other end is fixedly connected to the condensation section of the flexible heat pipe (1) through a heat-insulating fixing member (4).

6. The heat exchange device for the payload of a suborbital vehicle under dynamic acceleration conditions according to claim 5, wherein: The opening path of the chute (501) includes one of the following: radially opening along the bottom wall of the cylindrical housing (6), circumferentially opening along the bottom wall of the cylindrical housing (6), randomly shaped opening along the bottom wall of the cylindrical housing (6), or a combination of multiple opening methods.

7. The heat exchange device for the payload of a suborbital vehicle under dynamic acceleration conditions according to claim 1, characterized in that: The highly thermally conductive fixing member (3) is a copper gasket, and the heat-insulating fixing member (4) is a gasket made of ceramic fiber.

8. The heat exchange device for the payload of a suborbital aircraft under dynamic acceleration conditions according to claim 1, characterized in that: Both the cylindrical housing (6) and the encapsulation structure (2) of the heat source are split structures, and after the cylindrical housing (6) is assembled, it is locked by a lock (8).

9. The heat exchange device for a suborbital vehicle payload under dynamic acceleration conditions according to claim 1, characterized in that: The connecting member (9) includes a connecting plate and / or a connecting rod.

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