阅读说明：本技术 一种相变发汗冷却热防护结构及其构建方法 (Phase-change sweating cooling heat protection structure and construction method thereof ) 是由 胥蕊娜 姜培学 程志龙 于 2020-07-27 设计创作，主要内容包括：本发明涉及一种相变发汗冷却热防护结构及其构建方法,涉及飞行器热防护技术领域,包括：外层梯度孔隙发汗载体、内层梯度孔隙发汗载体、缓冲仓、压力仓和冷却剂管道；热负荷分布在外层梯度孔隙发汗载体的外表面上,外层梯度孔隙发汗载体的第一端热负荷温度高于外层梯度孔隙发汗载体的第二端热负荷温度；缓冲仓设置在外层梯度孔隙发汗载体和内层梯度孔隙发汗载体之间；压力仓设置在内层梯度孔隙发汗载体的外表面上；冷却剂管道设置在压力仓上；外层梯度孔隙发汗载体和内层梯度孔隙发汗载体根据热负荷分布规律控制冷却剂的流量。采用本发明可以改善相变发汗冷却过程中热负荷分布与实际冷却量不匹配的问题。(The invention relates to a phase-change sweating cooling thermal protection structure and a construction method thereof, relating to the technical field of thermal protection of aircrafts and comprising the following steps: the outer layer gradient pore sweating carrier, the inner layer gradient pore sweating carrier, the buffer bin, the pressure bin and the coolant pipeline; the heat load is distributed on the outer surface of the outer layer gradient pore sweating carrier, and the heat load temperature of the first end of the outer layer gradient pore sweating carrier is higher than that of the second end of the outer layer gradient pore sweating carrier; the buffer bin is arranged between the outer-layer gradient pore sweating carrier and the inner-layer gradient pore sweating carrier; the pressure chamber is arranged on the outer surface of the inner-layer gradient pore sweating carrier; the coolant pipeline is arranged on the pressure bin; the outer layer gradient pore sweating carrier and the inner layer gradient pore sweating carrier control the flow of the coolant according to the heat load distribution rule. The invention can solve the problem that the distribution of the heat load is not matched with the actual cooling amount in the phase-change sweating cooling process.)

1. A phase change transpiration cooling thermal protection structure, comprising: the outer layer gradient pore sweating carrier, the inner layer gradient pore sweating carrier, the buffer bin, the pressure bin and the coolant pipeline;

a thermal load distribution on an outer surface of the outer gradient pore sweating carrier, a first end thermal load temperature of the outer gradient pore sweating carrier being higher than a second end thermal load temperature of the outer gradient pore sweating carrier; the buffer bin is arranged between the outer layer gradient pore sweating carrier and the inner layer gradient pore sweating carrier; the pressure bin is arranged on the outer surface of the inner-layer gradient pore sweating carrier; the coolant pipeline is arranged on the pressure bin;

the inner-layer gradient pore sweating carrier controls the flow of the coolant entering the buffer bin according to a heat load distribution rule; the pressure chamber is used for driving the coolant in the coolant pipeline into the inner-layer gradient pore sweating carrier; the coolant undergoes a phase change in the inner gradient pore sweating carrier; the outer layer gradient pore sweating carrier controls the flow of the coolant flowing out of the outer layer gradient pore sweating carrier according to a heat load distribution rule.

2. The phase-change transpiration cooled heat shield of claim 1, further comprising support ribs disposed within the surge bin for connecting and supporting the outer gradient pore transpiration carrier and the inner gradient pore transpiration carrier.

3. The phase-change transpiration cooled heat shield of claim 1, further comprising sealing rings disposed at ports of the outer gradient pore transpiration carrier, the inner gradient pore transpiration carrier, and the surge bin; the sealing ring is used for sealing the outer layer gradient pore sweating carrier, the inner layer gradient pore sweating carrier and the buffer bin.

4. The phase change transpiration cooled thermal shield structure of claim 1, wherein the outer gradient porosity transpiration support is a porous structure having a porosity or pore size at a first end of the outer gradient porosity transpiration support that is greater than a porosity or pore size at a second end of the outer gradient porosity transpiration support.

5. The phase-change transpiration cooled thermal shield as recited in claim 4, wherein the gradient pore transpiration support is ceramic.

6. The phase change transpiration cooled thermal shield structure of claim 1, wherein the inner gradient porosity transpiration support is a porous structure having a porosity or pore size at a first end greater than a porosity or pore size at a second end of the inner gradient porosity transpiration support.

7. The phase-change transpiration cooling thermal protection structure of claim 6, wherein the inner gradient pore transpiration support is made of a refractory metal material.

8. The phase-change transpiration cooled thermal shield of claim 1, wherein the support ribs are disposed proximate the first end of the outer gradient pore transpiration carrier.

9. A method for constructing a phase-change sweating cooling thermal protection structure is characterized by comprising the following steps:

constructing a porous medium pore-skeleton interface curved surface equation of the gradient pore sweating carrier; the gradient pore sweating carrier comprises an outer layer gradient pore sweating carrier and an inner layer gradient pore sweating carrier;

determining a pore-framework interface equation, a pore part equation and a framework part equation according to the porous medium pore-framework interface surface equation;

establishing a mathematical model between pore parameters and characteristic parameters of the pore-skeleton interface equation; the porosity parameters include porosity and pore size;

obtaining the pore structure type, the change function of the pore parameters and the boundary equation of the gradient pore sweating carrier in the mathematical model;

iteratively calculating characteristic parameters of the pore-skeleton interface equation according to the pore structure type, the change function of the pore parameters, the boundary equation of the gradient pore sweat carrier, the pore part equation and the skeleton part equation in the mathematical model;

and constructing the gradient pore sweating carrier according to a boundary equation of the gradient pore sweating carrier, the characteristic parameters of the pore-skeleton interface equation and the pore-skeleton interface equation.

Technical Field

The invention relates to the technical field of thermal protection of aircrafts, in particular to a phase-change sweating cooling thermal protection structure and a construction method thereof.

Background

The hypersonic aircraft (Mach number Ma >5) and the high-thrust carrying platform are key links for guaranteeing national security and strategic benefit systems, and have great strategic significance and economic and social values. With the great improvement of the flight Mach number and the thrust, the thermal barrier becomes one of key technical bottlenecks and core problems which restrict the long-term flight and the reusability of the hypersonic aircraft in an extreme environment. The transpiration cooling has the advantages of strong cooling capacity, low coolant consumption, capability of realizing active control and the like, and is regarded as one of the technologies which are most hopeful to meet the thermal protection requirement of the hypersonic aircraft. The key components of the hypersonic aircraft (such as nose cone, wing leading edge, air inlet duct, and scramjet engine fuel injection support plate) bear extremely high heat load and are unevenly distributed, which causes the following problems: (1) the heat load borne by the surface of the sweating carrier is not matched with the actual cooling capacity seriously, so that the phenomenon of local ablation or coolant waste is caused, and the phenomenon is one of the main obstacles for limiting the phase-change sweating cooling efficiency and the improvement of the limit heat flow density; (2) when phase change sweating cooling brings high cooling capacity, unstable phase change process of the phase change sweating cooling under non-uniform heat load can cause large-amplitude temperature oscillation, steam blocking phenomenon appearing in a high heat flow density area enables pressure in a sweating carrier to fluctuate, further a gas-liquid interface is pushed to move back and forth, large-amplitude temperature oscillation appears on a cooled wall surface, and reliability and stability of a sweating cooling system face huge challenges. Under the constraint of the weight of the thermal protection system, the phase-change sweating cooling system is guaranteed to operate efficiently and reliably in a severe service environment, and the method has extremely important practical significance. The invention patent ZL201510205142.6 in China proposes a hypersonic aircraft nose cone based on a composite cooling mode, which is composed of a body made of high-temperature-resistant alloy or ceramic materials and in a microporous structure and two chambers, wherein a central hole is formed in the front edge of the nose cone to control the distribution amount of a coolant. The invention relates to a Chinese patent ZL201610990611.4, which provides a thermal protection structure for the front edge of a hypersonic vehicle, and is based on capillary force self-suction and self-adaptive sweating cooling technology, and the suction amount of a coolant can be automatically regulated and controlled according to thermal load. However, the above patent does not address the suppression of the phase change sweating cooling temperature oscillation problem. Therefore, it is necessary to provide a method for simultaneously solving the problems of poor matching between the local heat load and the cooling capacity of the phase-change sweating cooling and serious temperature oscillation.

Disclosure of Invention

The invention aims to provide a phase-change sweating cooling heat protection structure and a construction method thereof, which are used for solving the problem that the heat load distribution is not matched with the actual cooling capacity in the phase-change sweating cooling process.

In order to achieve the purpose, the invention provides the following scheme:

a phase change transpiration cooled thermal protection structure comprising: the outer layer gradient pore sweating carrier, the inner layer gradient pore sweating carrier, the buffer bin, the pressure bin and the coolant pipeline;

a thermal load distribution on an outer surface of the outer gradient pore sweating carrier, a first end thermal load temperature of the outer gradient pore sweating carrier being higher than a second end thermal load temperature of the outer gradient pore sweating carrier; the buffer bin is arranged between the outer layer gradient pore sweating carrier and the inner layer gradient pore sweating carrier; the pressure bin is arranged on the outer surface of the inner-layer gradient pore sweating carrier; the coolant pipeline is arranged on the pressure bin;

the inner-layer gradient pore sweating carrier controls the flow of the coolant entering the buffer bin according to a heat load distribution rule; the pressure chamber is used for driving the coolant in the coolant pipeline into the inner-layer gradient pore sweating carrier; the coolant undergoes a phase change in the inner gradient pore sweating carrier; the outer layer gradient pore sweating carrier controls the flow of the coolant flowing out of the outer layer gradient pore sweating carrier according to a heat load distribution rule.

Optionally, the phase-change sweating cooling heat protection structure further comprises a support rib, the support rib is arranged in the buffer bin, and the support rib is used for connecting and supporting the outer gradient pore sweating carrier and the inner gradient pore sweating carrier.

Optionally, the phase-change sweating cooling thermal protection structure further comprises sealing rings, and the sealing rings are arranged at the ports of the outer-layer gradient pore sweating carrier, the inner-layer gradient pore sweating carrier and the buffer bin; the sealing ring is used for sealing the outer layer gradient pore sweating carrier, the inner layer gradient pore sweating carrier and the buffer bin.

Optionally, the outer gradient pore sweat carrier is a porous structure, and the porosity or pore diameter of the first end of the outer gradient pore sweat carrier is greater than the porosity or pore diameter of the second end of the outer gradient pore sweat carrier.

Optionally, the outer gradient pore sweating carrier is made of ceramic.

Optionally, the inner gradient pore sweat carrier is a porous structure, and the porosity or pore diameter of the first end of the inner gradient pore sweat carrier is larger than the porosity or pore diameter of the second end of the inner gradient pore sweat carrier.

Optionally, the inner-layer gradient pore sweating carrier is made of a high-temperature-resistant metal material.

Optionally, the support ribs are disposed proximate to the first end of the outer gradient pore sweat carrier.

A phase-change sweating cooling thermal protection structure construction method comprises the following steps:

constructing a porous medium pore-skeleton interface curved surface equation of the gradient pore sweating carrier; the gradient pore sweating carrier comprises an outer layer gradient pore sweating carrier and an inner layer gradient pore sweating carrier;

determining a pore-framework interface equation, a pore part equation and a framework part equation according to the porous medium pore-framework interface surface equation;

establishing a mathematical model between pore parameters and characteristic parameters of the pore-skeleton interface equation; the porosity parameters include porosity and pore size;

obtaining the pore structure type, the change function of the pore parameters and the boundary equation of the gradient pore sweating carrier in the mathematical model;

iteratively calculating characteristic parameters of the pore-skeleton interface equation according to the pore structure type, the change function of the pore parameters, the boundary equation of the gradient pore sweat carrier, the pore part equation and the skeleton part equation in the mathematical model;

and constructing the gradient pore sweating carrier according to a boundary equation of the gradient pore sweating carrier, the characteristic parameters of the pore-skeleton interface equation and the pore-skeleton interface equation.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

the invention provides a phase-change sweating cooling heat protection structure and a construction method thereof. In addition, the outer layer gradient pore sweating carrier can enable gas to be smoothly discharged from a position with smaller flow resistance, and effectively avoids the phenomenon of local steam blockage.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic view of a phase change transpiration cooling thermal shield of the present invention;

FIG. 2 is a cross-sectional view of a phase change transpiration cooled thermal shield according to the invention;

FIG. 3 is a flow chart of a method for constructing a phase-change sweating cooling thermal protection structure according to the present invention;

FIG. 4 is a schematic diagram of a method for constructing a phase-change sweating cooling thermal protection structure according to the present invention.

Description of the symbols:

1-outer layer gradient pore sweating carrier, 2-buffer bin, 3-support rib, 4-inner layer gradient pore sweating carrier, 5-coolant pipeline, 6-pressure bin and 7-sealing ring.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a phase-change sweating cooling heat protection structure and a construction method thereof, which are used for solving the problem that the heat load distribution is not matched with the actual cooling capacity in the phase-change sweating cooling process.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1, a represents a sectional view of the phase-change sweating cooling thermal protection structure along the direction a, the phase-change sweating cooling thermal protection structure provided by the invention comprises: the outer layer gradient pore sweating carrier 1, the inner layer gradient pore sweating carrier 4, the buffer bin 2, the pressure bin 6 and the coolant pipeline 5.

The heat load is distributed on the outer surface of the outer layer gradient pore sweating carrier 1, and the heat load temperature of the first end of the outer layer gradient pore sweating carrier 1 is higher than the heat load temperature of the second end of the outer layer gradient pore sweating carrier 1; the buffer bin 2 is arranged between the outer layer gradient pore sweating carrier 1 and the inner layer gradient pore sweating carrier 4; the pressure chamber 6 is arranged on the outer surface of the inner-layer gradient pore sweating carrier 4; a coolant pipe 5 is provided on the pressure chamber 6, the coolant pipe 5 being used for supply of coolant in the phase change transpiration cooling heat shield structure. The phase-change sweating cooling heat protection structure further comprises a support rib 3, the support rib 3 is arranged in the buffer bin 2, and the support rib 3 is used for connecting and supporting the outer layer gradient pore sweating carrier 1 and the inner layer gradient pore sweating carrier 4. As shown in fig. 2, the support ribs 3 are discretely arranged in the surge bin 2 in an in-line or staggered arrangement. The coolant is aviation kerosene, liquid oxygen, liquid hydrogen, water, propylene glycol or alcohol.

The inner-layer gradient pore sweating carrier 4 controls the flow of the coolant entering the buffer bin 2 according to the heat load distribution rule; the pressure chamber 6 is used for driving the coolant in the coolant pipeline 5 into the inner-layer gradient pore sweat carrier 4; the pressure bin 6 is also used for collecting liquid coolant; the coolant undergoes phase change in the inner gradient pore sweating carrier 4; the outer layer gradient pore sweating carrier 1 controls the flow of the coolant flowing out of the outer layer gradient pore sweating carrier 1 according to the heat load distribution rule.

In practical application, the phase-change sweating cooling heat protection structure further comprises a sealing ring 7, wherein the sealing ring 7 is arranged at the port parts of the outer-layer gradient pore sweating carrier 1, the inner-layer gradient pore sweating carrier 4 and the buffer bin 2; the sealing ring 7 is used for sealing the outer layer gradient pore sweating carrier 1, the inner layer gradient pore sweating carrier 4 and the buffer bin 2.

In practical application, the outer gradient pore sweat carrier 1 is a porous structure, and the porosity or pore diameter of the first end of the outer gradient pore sweat carrier 1 is larger than the porosity or pore diameter of the second end of the outer gradient pore sweat carrier 1. The porosity or pore size of the outer gradient pore sweat carrier 1 decreases gradually from the first end to the second end. The outer layer gradient pore sweating carrier 1 is made of ceramic.

In practical application, the inner gradient pore sweat carrier 4 is a porous structure, and the porosity or pore diameter of the first end of the inner gradient pore sweat carrier 4 is larger than that of the second end of the inner gradient pore sweat carrier 4. The inner gradient porosity sweat carrier 4 has a porosity or pore size that decreases gradually from the first end to the second end. The inner layer gradient pore sweating carrier 4 is made of high temperature resistant metal material.

In practical application, the support ribs 3 are disposed near the first end of the outer gradient pore sweat carrier 1.

The phase-change sweating cooling heat protection structure can be a flat plate structure or a shape structure of a nose cone and a nozzle throat part of the supersonic aircraft.

The principle of the phase-change sweating cooling heat protection structure is as follows:

the liquid coolant enters the pressure chamber through the coolant pipeline, and permeates into the inner gradient pore sweating carrier under the driving of pressure, the inner gradient pore sweating carrier is of a porous structure, wherein the pore diameter of a first end with high heat load temperature is larger than that of a second end, so that the inner gradient pore sweating carrier can realize the distribution of the coolant under the nonuniform heat load as required, the coolant is collected in the buffer chamber and then enters the outer gradient pore sweating carrier, when the heat load temperature is higher, the liquid coolant completes the phase change process in the inner gradient pore sweating carrier, at the moment, gas (the viscosity of the gas is higher, the steam blockage phenomenon is easy to generate, the temperature oscillation is caused) is in the buffer chamber, the outer gradient pore sweating carrier is of a porous structure, wherein the pore diameter of the first end is larger than that of the second end, therefore, the outer gradient pore sweating carrier can enable the gas to be smoothly discharged from a position with smaller flow resistance, the phenomenon of local steam blockage is effectively avoided, the coolant finally enters the high-temperature high-speed main flow, a layer of compact air film is formed on the protected wall surface, heat transfer from the main flow to the protected wall surface is blocked, and the thermal protection effect is achieved.

As shown in fig. 3, the method for constructing a phase-change transpiration cooling thermal protection structure provided by the invention comprises the following steps:

step 101: constructing a porous medium pore-skeleton interface curved surface equation of the gradient pore sweating carrier; the gradient pore sweating carrier comprises an outer layer gradient pore sweating carrier and an inner layer gradient pore sweating carrier.

Step 102: and determining a pore-framework interface equation, a pore part equation and a framework part equation according to the porous medium pore-framework interface curved surface equation.

Step 103: establishing a mathematical model between pore parameters and characteristic parameters of a pore-skeleton interface equation; the porosity parameters include porosity and pore size.

Step 104: and obtaining the pore structure type, the change function of the pore parameters and the boundary equation of the gradient pore sweating carrier in the mathematical model.

Step 105: and (3) according to the pore structure type, the change function of the pore parameters, the boundary equation of the gradient pore sweat carrier, the pore part equation and the skeleton part equation in the mathematical model, iteratively calculating the characteristic parameters of the pore-skeleton interface equation.

Step 106: and constructing the gradient pore sweating carrier according to a boundary equation of the gradient pore sweating carrier, the characteristic parameters of the pore-skeleton interface equation and the pore-skeleton interface equation.

The invention also provides a specific method for constructing the phase-change sweating cooling thermal protection structure, as shown in fig. 4.

Step 1: a curved surface equation is provided for constructing a pore-skeleton interface of the porous medium, and the curved surface equation has four types, namely W type, P type, D type and G type, and is shown in formulas (1) to (4):

wherein a and b are constants, p (x, y, z) and q (x, y, z) are characteristic parameters of a pore-skeleton interface equation of the porous medium, and the pore distribution rule of the gradient pore sweat carrier can be adjusted by controlling the change of p (x, y, z) and q (x, y, z).

Step 2: obtaining G (x, y, z) ═ 0 as the pore-skeleton interface equation, G (x, y, z)>0 is the pore fraction equation, G (x, y, z)<0 is a skeleton part equation (vice versa), and a mathematical model is established between the pore parameters and characteristic parameters p (x, y, z) and q (x, y, z) of a pore-skeleton interface equation G (x, y, z) ═ 0, wherein the pore parameters comprise porosity and pore diameter d_pAs shown in equations (5) and (6), where V represents the volume.

＝V_G(x,y,z)＞0/(V_G(x,y,z)＜0+V_G(x,y,z)＞0) (5)

Wherein, is porosity, d is pore diameter, and p is a characteristic parameter.

And step 3: the user selects the pore structure type, and inputs the pore parameters porosity as a + bx/L (x is more than or equal to 0 and less than or equal to L) and pore diameter dp as c + dx/L (pore diameter unit is mum, x is more than or equal to 0 and less than or equal to L), and gives the gradient pore sweating carrier model boundary: length (L), width (W), and height (H); the porosity and pore size may also be constant. Wherein, is porosity, L is length of the gradient pore sweating carrier, a is porosity of the first end of the gradient pore sweating carrier, and b is change rate of the porosity along the x direction; dp is the pore diameter, c is the pore diameter of the first end of the gradient pore sweating carrier, d is the rate of change of the pore diameter along the x direction.

And 4, step 4: iteratively calculating characteristic parameters p (x, y, z) and q (x, y, z) in a pore-skeleton interface equation, and uniformly sampling the porosity and the pore diameter respectively for N times (N times)_iAnd d_pI, i ═ 1,2,3 … … N), and then the porosities were calculated, respectively_iAnd an aperture d_pI corresponds to p_iAnd q is_i. The calculation method comprises assigning initial values to equation characteristic parameters p (x, y, z) and q (x, y, z), calculating porosity according to equation (1), and calculating pore diameter d according to equation (2)_pThen calculating the residual error between the calculated value and the actual design value of the pore parameters, finishing iteration when the residual error is small enough, and outputting the characteristic parameter p of the equation_iAnd q is_i(ii) a Then according to p_iAnd q is_iAnd fitting curves p (x) and q (x), constructing a gradient pore sweating carrier based on a pore-skeleton interface equation and boundary conditions, and deriving a model.

The phase-change sweating cooling heat protection structure and the construction method thereof provided by the invention have the following advantages:

(1) the double-layer gradient pore sweating carrier can realize the distribution of cooling fluid as required under the nonuniform heat load, is favorable for improving the problem of poor matching of phase-change sweating cooling heat load distribution and cooling capacity, and can supplement the cooling liquid in a high heat flow density area in time, so that a gas-liquid interface is completely positioned in the gradient pore sweating carrier, and generated steam can be discharged from the position with larger porosity and pore diameter as soon as possible after being collected in a buffer bin, thereby avoiding the phenomenon of large-area steam blockage, and greatly reducing the temperature oscillation amplitude.

(2) The construction method of the phase-change sweating cooling thermal protection structure is simple in implementation process, can realize quantitative control on pore parameters (porosity and aperture), can flexibly change the appearance structure of the gradient pore sweating carrier, is not limited to a flat plate structure, and can also be a nose cone or nozzle throat structure of an ultrasonic aircraft, as long as the structure can be described by a mathematical equation.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.