CN119637069B

CN119637069B - Microchannel device for phase change sweating and application method

Info

Publication number: CN119637069B
Application number: CN202411812851.6A
Authority: CN
Inventors: 胡文杰; 吴昌聚; 胡国暾; 石伟; 邱云龙; 陈伟芳
Original assignee: Zhejiang University ZJU; Beijing Institute of Astronautical Systems Engineering
Current assignee: Zhejiang University ZJU; Beijing Institute of Astronautical Systems Engineering
Priority date: 2024-12-10
Filing date: 2024-12-10
Publication date: 2025-09-16
Anticipated expiration: 2044-12-10
Also published as: CN119637069A

Abstract

The invention discloses a micro-channel device for phase change sweating and an application method, and belongs to the technical field of aircraft heat protection. The structure is composed of a solid inner wall, a transport phase change layer and a sweating outer wall surface from inside to outside in sequence, and mainly comprises a bottom plate, a porous rib wall, a solid outer wall, an inlet runner, a main runner, a branch runner and the like. The bottom plate is an entity inner wall and plays roles in supporting and transporting; the flow channel can be divided into an inlet flow channel, a main flow channel and a branch flow channel, and the cooling medium sequentially passes through the inlet flow channel, the main flow channel and the branch flow channel; the cooling medium is ejected into the external flow field through the porous rib walls which are arranged periodically; the invention has the characteristics of integrated structure, thin thickness, uniform perspiration and high efficiency, and can provide a new way for long-time cross-domain navigation heat protection of high-speed aircrafts.

Description

Microchannel device for phase change sweating and application method

Technical Field

The invention relates to the technical field of high-speed aircraft heat protection, in particular to a micro-channel device for phase change sweating and an application method.

Background

When the aircraft is flown in a dense atmosphere at high mach numbers for a long period of time, the temperature of the exterior surfaces of the aircraft may reach approximately 3000 degrees celsius under the influence of pneumatic heating. In order to ensure that the aircraft fuselage and its internal environment work properly within the allowable temperature range, an effective structural thermal protection design is required. The sweating cooling has the advantages of reducing the surface aerodynamic resistance, reducing the surface infrared target characteristics, resisting oxidation and ablation and the like, and is now a key technology for active heat protection of various high-speed aircrafts in aerospace.

Aircraft designs are often pursued to be extremely lightweight to achieve higher, faster, more distant goals. When the sweatcooling technology is applied to large-area areas of an aircraft, serious limitations on thickness and weight are faced. Therefore, the large area sweat structure should be as thin as possible. The thermal protection of large areas requires uniform sweating and internal uniform cooling, which puts high demands on uniform distribution of cooling medium within the structure. Meanwhile, the reliability and completeness requirements of the thin-wall type heat protection structure meet the requirements of engineering application.

Patent CN117324638a discloses a laminated sheet sweating cooling structure, which realizes sweating cooling by transporting to a porous surface layer through a solid substrate with a four-level effusion cavity transporting channel. This solution allows a uniform distribution of the cooling medium under defined thickness and area dimensions. But this structure has some problems. First, in such a dendritic multi-stage distribution flow channel structure, clogging of the upper flow channel may cause insufficient supply of the lower flow channel cooling medium or even drying, thereby causing failure of the corresponding surface local area to achieve sweat cooling. Secondly, the liquid cooling medium has flow instability caused by phase change in the transportation process and increases the dryness of the path, so that the phenomenon that a local flow passage is blocked by bubbles and is difficult to wet is caused, and the problem of uneven distribution of cooling working media can occur in each stage of liquid collecting cavities. Finally, the spanwise area of the structure is limited in expansion, i.e., it is difficult to further expand the spanwise area under given thickness constraints.

Disclosure of Invention

Aiming at the requirements of high-speed aircraft on heat protection performance and the size constraint of a thin-wall heat protection structure, the invention aims to overcome the defects of the prior art and provide a micro-channel device for phase change sweating and an application method. The device can realize uniform transportation of cooling medium while meeting thickness dimension constraint, reduce the risk of difficult sweating of local surface caused by local flow channel blockage or insufficient medium transportation capacity, realize uniform sweating cooling effect and have better spreading area dimension expansion capacity.

The technical scheme for achieving the aim of the invention is as follows:

the micro-channel device for phase change sweating has a three-layer jogged structure, namely a bottom plate, a rib wall and a solid outer wall in sequence, wherein the left side and the right side are periodically arranged multi-connected structures;

The porous rib walls and the solid rib walls are arranged in parallel at intervals, and the solid rib walls are positioned at one side or the other side of one of the multi-joint structures and are staggered to play a role in blocking;

the outer wall of the entity is provided with cross rib plates which are distributed vertically and horizontally at intervals, the cross rib plates are distributed in a staggered manner, and the gaps of the cross rib plates are filled by porous rib walls;

the bottom plate, the porous rib wall, the solid rib wall and the transverse rib plate of the solid outer wall form a branch flow channel in a surrounding mode;

The bottom plate, the end face of the solid rib wall, the end face of the porous rib wall and the longitudinal rib plates of the solid outer wall form a main runner in a surrounding manner, and the main runner and the branch runner are positioned on the same plane and are mutually perpendicular;

The main runner and the branch runner are used for conveying cooling medium, and cooling the heat protection structure through convection heat transfer and medium phase change;

the bottom plate is provided with a cooling medium inlet, an inlet runner and a main runner inlet;

The porous rib wall is flush with the outer surface of the solid outer wall to form a sweating outer wall surface.

The inner side of the bottom plate is provided with a cooling medium inlet which is connected with a liquid supply pipeline, and the liquid cooling medium input by the cooling medium inlet is distributed to each main runner through each main runner inlet by the internal inlet runners which are distributed in parallel.

The cooling medium enters the micro-channel device from the cooling medium inlet of the bottom plate to finally flow out of the porous rib wall, is subjected to a liquid-to-two-phase mixed state, and finally becomes a series of gaseous transition states;

the cooling medium is mainly in a liquid state when transported in an inlet runner in the bottom plate, then enters a main runner and a branch runner for transporting the phase-change layer to generate phase change, and cooling of the structure is realized through convection heat transfer and phase change heat absorption;

the cooling working medium in the branch flow channel can only flow out through the porous rib walls at the two sides, further changes phase into gas state in the flowing process of the porous structure and enters the external flow field, and a continuous gas film is formed on the near wall surface.

The integral structure of the device is formed by a laser selective melting additive manufacturing technology, wherein the porosity and the pore size of the porous rib wall are regulated and controlled by the additive manufacturing technology.

The device expands the size according to the heat protection requirement of the wall surface and the structural characteristics of the wall surface of the aircraft, namely, the flow channel structures of all stages are distributed in a periodic structure, and the area size is changed by changing the number of periods.

The micro-channel device for phase change sweating regulates the heat protection performance of the structure by designing each flow channel and the structure size and combining the regulation of the flow of the cooling medium.

The sectional areas of the branch flow channel, the main flow channel and the inlet flow channel of the micro-channel device for phase change sweating should be sequentially increased.

The application method of the micro-channel device for phase change sweating,

The liquid cooling medium enters the micro-channel structure from the cooling medium inlet on the bottom plate, is conveyed through the cascade flow channel network of the inlet flow channel, the main flow channel and the branch flow channel, is uniformly distributed in the conveying phase-change layer, realizes structural cooling through convection heat transfer and phase change, and finally, the gaseous working medium diverges from the porous rib wall to enter the external flow field to form a gas film, changes the near-wall flow field structure and reduces the input aerodynamic heat;

Each main runner is connected with one inlet runner at one side only through a main runner inlet and is distributed in a staggered way, namely, the cooling medium of the adjacent main runners is sourced from different inlet runners, so that the flowing directions of the cooling medium in every two adjacent main runners are opposite; the cooling medium in every two adjacent branch flow channels is sourced from the adjacent main flow channels, namely, the cooling medium at the two sides of each porous rib wall is sourced from the adjacent main flow channels, and the flow directions in the branch flow channels at the two sides are opposite; the cooling medium is supplied to the branch channels on two sides of the main channel by each main channel, and inlets of the corresponding branch channels on two sides are distributed in a staggered way;

The invention has the beneficial effects that:

The medium conveying runner network with the structure can be divided into three stages of an inlet runner, a main runner and a branch runner. Spatially, each stage of flow channels is staggered, such as parallel staggered inlet flow channels, each having an independent cooling medium inlet. In the middle transport phase change layer, main flow channels connected with different inlet flow channels are staggered, and branch flow channels connected with different main flow channels are also staggered. This allows adjacent channels to still provide cooling medium in the event of a localized blockage or damage to a portion of a channel of a given stage. For example, when one branch channel is blocked, the adjacent branch channels at two sides can still provide cooling medium for the porous rib walls at two sides of the blocked branch channel due to the fact that the cooling medium is sourced from the other channel network. If one main runner is blocked, the porous rib walls in the multi-connected structures at two sides of the main runner can still supply liquid through the adjacent main runner to avoid drying. If one inlet flow passage is blocked, the adjacent inlet flow passage can still provide cooling medium for the porous rib wall in the transport phase change layer. The staggered arrangement mode of the multi-stage flow channels can realize relatively uniform heat protection performance and improve the safety and reliability of operation.

The invention has the characteristics of integrated structure, thin thickness, uniform sweating and high efficiency, and can provide a new way for long-time cross-domain navigation heat protection of high-speed aircrafts.

Drawings

FIG. 1 is a schematic view of the micro-channel structure for phase change sweating, and arrows are schematic views of the sweating direction.

Fig. 2 is a schematic view of the bottom plate 1 and part of the flow channels of the microchannel structure, and arrows show the flow direction of the cooling medium.

FIG. 3 is a top view of a microchannel structured floor structure with arrows indicating the direction of flow of the cooling medium.

Fig. 4 is a bottom view of the bottom plate structure of the microchannel structure, with arrows indicating the flow direction of the cooling medium.

Fig. 5 is a schematic diagram of the phase change sweating layer structure, and arrows are schematic diagrams of the flow direction and the sweating direction of the cooling medium.

FIG. 6 is a schematic diagram of the transport of the cooling medium in the phase change sweat layer, with arrows indicating the direction of flow of the cooling medium.

Fig. 7 is an area expansion schematic of a phase-change sweat-releasing microchannel structure.

In the figure, a bottom plate 1, a cooling medium inlet 1.1, a main channel inlet 1.2, a porous rib wall 2, a solid rib wall 3, a solid outer wall 4, an inlet channel 5, a main channel 6, and a branch channel 7.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the detailed description and the accompanying drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention as claimed.

A micro-channel structure for phase change sweating is shown in figure 1, and comprises a solid inner wall, a transport phase change layer and a sweating outer wall surface from inside to outside. The bottom plate 1 is a solid inner wall and plays a role of structural support, and an inlet runner 5 in the bottom plate can transport cooling medium. The porous rib wall 2 and the solid rib wall 3 are connected on the bottom plate 1 to form a transport phase change layer, a cooling medium is distributed to a main runner 6 and a branch runner 7 which are formed by structural connection through an inlet runner 5 for transport, and cooling of the heat protection structure is realized through convection heat transfer and medium phase change. The porous rib wall 2 is connected with the solid outer wall 4 and keeps the outer surface flush, forming an outer perspiration wall surface with the perspiration areas distributed in a staggered and discrete manner. The cooling medium in the gas-liquid mixed state enters the porous structure of the porous rib wall 2 through the branch flow passages 7 at the two sides of the porous rib wall 2 to further fully perform phase change and absorb heat, and the cooling medium becomes gas and diverges into an external flow field to form a gas film as shown by arrows in the figure.

Fig. 2 shows a sectional view of the structure of the base plate 1, fig. 3 and 4 show a top view and a bottom view, respectively, of the base plate 1, on the bottom side of which a cooling medium inlet 1.1 is arranged, which can be connected to the liquid supply line of the cooling system by means of different connection forms, parallel inlet channels 5 being arranged in the structure, each inlet channel 5 having a corresponding cooling medium inlet 1.1. The cooling medium flows in the inlet channels 5 and is distributed into the upper main channels 6 via the main channel inlets 1.2 arranged at intervals, so that the cooling medium flows in opposite directions between adjacent main channels 6, i.e. counter-channels. According to the main runner 6, the base plate 1 can be partially embedded, the cross-sectional area of the runner is increased within a limited width, and the medium conveying capacity is enhanced. The inlet flow channels 5 are a plurality of main flow channels for conveying cooling medium, and the sectional area of the inlet flow channels is larger than that of the main flow channels 6 to a certain extent.

As shown in fig. 5 and 6, which are respectively an axial view and a top view of an intermediate transport phase change layer structure with the bottom plate 1 and the solid outer wall 4 removed, each main runner 6 transports cooling working medium to the side runners 7 connected with the main runner 6 on both sides, the side runners on the same side are arranged at intervals, and the middle is the side runner 7 connected with the adjacent main runner 6. The opposite branch channels of the main channel 6 are arranged in a staggered manner, so that the opposite side of the channel opening is avoided, and the unstable characteristics of the flowing phase change process in the opposite branch channel 7, such as the mutual influence of pressure fluctuation, flow fluctuation and the like, are reduced. The flow directions of the branch flow channels 7 at the two sides of the porous rib wall 2 are opposite, the cooling working medium comes from the adjacent main flow channel 6 which flows reversely, and the cooling medium mixed with the gas and the liquid at the two sides can enter the structure of the porous rib wall 2 for further phase change so as to be dispersed into an external high-speed flow field. The countercurrent arrangement of the multistage flow channels ensures that the temperature of the axial along-path structure of the main flow channel is relatively uniform, and the flow of the cooling medium conveyed to each porous rib wall 2 along the path is complemented and more uniform through the branch flow channels 7 at the two sides. At the same time, the cooling medium input flow axially distributed by the single porous rib wall 2 structure is also relatively uniform. The uniform distribution and transportation of the cooling medium in the planar structure are realized to a certain extent, the uniform cooling medium is also provided for the structures of the porous rib walls 2, and the medium flow of the air film formed by the sweating areas of the outer wall surface is relatively uniform. Therefore, the in-plane thermal protection effect of the compact and interweaved multi-stage countercurrent flow passage structure is uniform. Meanwhile, the structural heat conduction can weaken local temperature fluctuation caused by two-phase flow instability caused by phase change to a certain extent.

Fig. 7 is a schematic view showing the area expansion of the microchannel structure for phase change sweating. The thin-wall micro-channel structure can be expanded in size according to the heat protection requirement of the wall surface and the structural characteristics of the wall surface of the aircraft, namely, the multi-joint structure is periodically distributed, and the area size can be changed by changing the number of periods. The illustration in the figure can be expanded in both the transverse direction and the longitudinal direction, and the number of the actually expanded multi-connected structure is not required to be a multiple of three. The structure can be used as a modularized component for assembly, is convenient for generalized design and batch assembly according to actual appearance and area, and finally is spliced and combined to form a large-area sweating cooling structure, so that the structure has a strong practical value.

The integral structure can be formed by a laser selective melting additive manufacturing technology, and the size of each structure can be adjusted according to different heat protection requirements and actual performance performances, such as the size of a runner, the wall thickness of the porous rib wall 2 and the like. Wherein the porosity and pore size of the porous rib wall 2 can be regulated and controlled by an additive manufacturing process to adapt to different heat protection requirements. The capillary transport capacity of the porous rib wall 2 structure can be improved through design and manufacture, and the medium transport performance in the structure is further improved.

The cooling medium of each porous rib wall 2 structure originates from the channel network of different main channels 6, so that the risk of structural damage caused by local heat transfer deterioration due to local channel blockage, increased flow resistance or local dry liquid is reduced to a certain extent. If one branch flow passage 7 is blocked, the adjacent branch flow passage 7 can still provide cooling medium. If one main runner 6 is blocked, the runner network where the adjacent main runner 6 is located can still provide cooling medium. If a pipeline where one inlet runner 5 is located is damaged, enough cooling medium cannot be provided, the adjacent inlet runner 5 can increase the flow rate, and the cooling medium is continuously provided for all the porous rib walls 2. The runner network structure design can realize relatively uniform heat protection performance and improve the safety and reliability of operation.

In practical engineering application, the regulation and control of the heat protection performance can be realized by regulating the flow of the cooling medium of different inlet channels 5.

Further combinations of the features of the above embodiments are possible, and for brevity, all of the possible combinations of features in the above embodiments are not described, however, they should be considered as being within the scope of the description provided herein, as long as there is no contradiction between these features.

Claims

1. A microchannel device for phase change sweating, characterized by: a three-layer interlocking structure on the top and bottom, which is a bottom plate (1), a rib wall, and a solid outer wall (4) in sequence; a periodically arranged multi-link structure on the left and right; and the multi-link structure is expandable;

The rib wall comprises a porous rib wall (2) and a solid rib wall (3); the porous rib wall (2) and the solid rib wall (3) are arranged in parallel and spaced apart, and the solid rib wall (3) is located on one side or the other side of one of the multiple-linked structures, and is arranged in a staggered manner to play a barrier role;

The solid outer wall (4) is a rib plate distributed at intervals in the vertical and horizontal directions, the transverse rib plates are staggered, and the gaps between the rib plates are filled with the porous rib wall (2);

The bottom plate (1), the porous rib wall (2), the solid rib wall (3), and the transverse ribs of the solid outer wall (4) together form a branch channel (7);

The bottom plate (1), the end surface of the solid rib wall (3), the end surface of the porous rib wall (2), and the longitudinal ribs of the solid outer wall (4) together form a main flow channel (6); the main flow channel (6) and the branch flow channel (7) are located in the same plane and are perpendicular to each other;

The main channel (6) and the branch channel (7) are used to transport the cooling medium; the cooling of the thermal protection structure is achieved through convection heat transfer and medium phase change;

The bottom plate (1) is provided with a cooling medium inlet (1.1), an inlet flow channel (5), and a main flow channel inlet (1.2);

The outer surfaces of the porous rib wall (2) and the solid outer wall (4) are flush with each other, forming a sweating outer wall surface;

The inner side of the bottom plate (1) is provided with a cooling medium inlet (1.1) connected to a liquid supply pipeline, and parallel internal inlet flow channels (5) distribute the liquid cooling medium input from the cooling medium inlet (1.1) to each main flow channel (6) through each main flow channel inlet (1.2);

The cooling medium undergoes a series of transition states from a liquid state to a two-phase mixed state and finally to a gaseous state during the process of entering the microchannel device from the cooling medium inlet (1.1) of the bottom plate (1) to finally flowing out of the porous rib wall (2);

The cooling medium is mainly in liquid state when transported in the inlet flow channel (5) in the bottom plate (1), and then undergoes phase change when entering the main flow channel (6) and the branch flow channel (7) of the transport phase change layer, and realizes cooling of the structure through convection heat transfer and phase change heat absorption;

The cooling medium in the branch channel (7) can only flow out through the porous rib walls (2) on both sides, and further changes into a gaseous state during the flow of the porous structure, enters the external flow field, and forms a continuous gas film near the wall surface.

2. The microchannel device for phase change sweating according to claim 1 is characterized in that the overall structure of the device is formed by laser selective melting additive manufacturing technology, wherein the porosity and pore size of the porous rib wall (2) are controlled by the additive manufacturing process.

3. The microchannel device for phase change sweating as described in claim 1 is characterized in that the device is scalable based on the wall thermal protection requirements and the structural characteristics of the aircraft wall. That is, the flow channel structure at each level is distributed in a periodic structure, and the area size is changed by changing the number of periods.

4. The microchannel device for phase change perspiration according to claim 1, characterized in that the cross-sectional areas of the branch channel (7), the main channel (6), and the inlet channel (5) should increase in sequence.

5. The application method of the microchannel device for phase change perspiration according to claim 1, characterized in that:

The liquid cooling medium enters the microchannel structure from the cooling medium inlet (1.1) on the bottom plate (1), is transported through the cascade flow channel network of the inlet flow channel (5), the main flow channel (6), and the branch flow channel (7), and is evenly distributed in the transport phase change layer. The structure is cooled by convection heat transfer and phase change. Finally, the gaseous working medium diverges from the porous rib wall (2) into the external flow field, forming an air film, changing the near-wall flow field structure, and reducing the input aerodynamic heat.

Each main channel (6) is connected to the inlet channel (5) on one side only through the main channel inlet (1.2), and the cooling media are staggered, that is, the cooling media of adjacent main channels (6) are derived from different inlet channels (5), so that the cooling media in each two adjacent main channels (6) flow in opposite directions;

The cooling medium in each of two adjacent branch channels (7) originates from the adjacent main channel (6), that is, the cooling medium on both sides of each porous rib wall (2) originates from the adjacent main channel (6), and the flow directions in the branch channels (7) on both sides are also opposite;

Each main channel (6) supplies cooling medium to the branch channels (7) on both sides thereof, and the inlets of the branch channels (7) on both sides are staggered;

The medium of the sweating zones staggered and discretely distributed on the sweating outer wall is derived from each porous rib wall (2);

The non-sweating solid outer wall (4) structure achieves cooling through air film insulation, structural heat conduction, and heat transfer through the internal flow channel.