Gas-phase sweating cooling thermal protection system and method with flow self-adaptive control function

Abstract

The invention discloses a gas-phase sweating cooling thermal protection system with self-adaptive flow control. The gas-phase sweating cooling thermal protection system comprises a porous structure, a compact material structure, a porous structure inner cavity, a sweating agent supply pipeline, a pressure regulating device, a sweating agent gas source and an electronic control system. The invention further discloses a flow self-adaptive control gas phase sweating cooling thermal protection method, and when the thermal environment state is stabilized, the sweating agent supply flow q of the sweating agent gas source is determined according to the pneumatic heat flow Q on the outer side of the porous structure, the pneumatic pressure P1 on the outer side of the porous structure and the pressure P2 of an inner cavity of the porous structure; in an unstable thermal environment state, pre-judging changes of Q and P1 at the next moment, and adjusting q in advance; meanwhile, the temperature T of the porous structure is monitored, and when T rises to be higher than the upper limit of the optimal temperature interval, the sweating agent flow increment is started till T falls to the lower limit of the optimal temperature interval. The pneumatic thermal protection requirement can be efficiently met with the lower sweating agent flow requirement, and the pneumatic thermal protection device has wide application prospects in the technical field of pneumatic thermal protection.

Description

Technical Field

[0001] The invention relates to a sweating cooling thermal protection system for realizing flow adaptive control based on a three-degree-of-freedom collaborative feedback mechanism, and belongs to the technical field of pneumatic thermal protection. Background Art

[0002] Gas-phase transpiration cooling technology is an efficient active control thermal protection technology. During the transpiration cooling process, the transpiration agent flows out from the outer surface of the structure to form an induced airflow, thereby reducing the aerodynamic heating heat flow. Therefore, the aerodynamic heating heat flow can be controlled by controlling the flow of the transpiration agent. On the other hand, the transpiration cooling technology needs to carry auxiliary masses such as transpiration agents, which improves the compensation of the thermal protection system. Therefore, how to meet the aerodynamic thermal protection requirements with low compensation and high efficiency is the key issue of transpiration cooling technology.

[0003] In the current implementation of transpiration cooling technology, a discrete step-type transpiration agent flow supply strategy is often used to cope with the ever-changing thermal environment. Although this solution is effective, as a conservative design method, it will waste transpiration agent flow at specific times and local locations, increasing the compensation of the thermal protection system. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects and provide a gas-phase transpiration cooling thermal protection system and method with flow adaptive control, which solves the technical problem that the current transpiration cooling technology will cause waste of transpiration agent flow at specific times and local locations. The present invention can efficiently meet the aerodynamic thermal protection requirements with lower transpiration agent flow requirements, and has broad application prospects in the field of aerodynamic thermal protection technology.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a diaphoretic cooling thermal protection system that realizes flow adaptive control based on a three-degree-of-freedom collaborative feedback mechanism. The system obtains real-time perception of the aerodynamic heating heat flow (degree of freedom 1), aerodynamic pressure (degree of freedom 2), and structural temperature (degree of freedom 3) outside the heat protection structure through three methods: comprehensive pre-stored data retrieval, real-time data measurement, and rapid iterative calculation, and then regulates the supply pressure of the diaphoretic agent according to the time-varying characteristics of each degree of freedom. Therefore, compared with previous solutions, the present invention can efficiently meet the requirements of aerodynamic thermal protection with a lower diaphoretic agent flow demand.

[0007] A flow adaptively controlled gas phase transpiration cooling thermal protection system comprises: a porous structure, a dense material structure, a porous structure inner cavity, a transpiration agent supply pipeline, a pressure regulating device, a transpiration agent gas source and an electronic control system;

[0008] The dense material structure and the porous structure are combined to form a hollow structure, and the internal cavity of the hollow structure is the inner cavity of the porous structure;

[0009] A diaphoretic gas source located outside the inner cavity of the porous structure is connected to the inner cavity of the porous structure through a diaphoretic supply pipeline, and the diaphoretic gas source is used to supply diaphoretics to the inner cavity of the porous structure;

[0010] A pressure regulating device is provided on the diaphoretic agent supply pipeline;

[0011] The electronic control system pre-stores the aircraft status data, and obtains the aerodynamic heat flux Q outside the porous structure and the aerodynamic pressure P1 outside the porous structure by checking the MAP diagram of the pre-stored aircraft status data in real time; the electronic control system simultaneously measures the temperature T of the porous structure and the pressure P2 of the inner cavity of the porous structure in real time, and controls the pressure regulating device according to the temperature T of the porous structure, the pressure P2 of the inner cavity of the porous structure, the aerodynamic heat flux Q outside the porous structure and the pneumatic pressure P1 outside the porous structure, thereby realizing real-time control of the diaphoretic flow rate q supplied by the diaphoretic gas source.

[0012] A method for heat protection by gas phase sweating cooling with flow adaptive control is implemented by using the above-mentioned heat protection system for gas phase sweating cooling with flow adaptive control, comprising:

[0013] S1 determines the thermal environment state of the aircraft. If the aircraft is in a stable thermal environment state, proceed to step S2; otherwise, proceed to step S3;

[0014] The S2 electronic control system determines the flow rate q of the diaphoretic agent supplied by the diaphoretic agent source according to the temperature T of the porous structure 1, the pneumatic heat flow Q outside the porous structure, the pneumatic pressure P1 outside the porous structure, the pressure P2 inside the porous structure, and the pre-set temperature control target T_goal of the porous structure;

[0015] The S3 electronic control system predicts the changes in the aerodynamic heat flow Q and the aerodynamic pressure P1 outside the porous structure at the next moment, and adjusts the diaphoretic air source to supply the diaphoretic flow rate q in advance according to the predicted results.

[0016] Furthermore, in step S1, the method for determining whether the aircraft is in a stable thermal environment state includes:

[0017] Set the current time as t. When the change rates of the aerodynamic heat flux Q and the aerodynamic pressure P1 outside the porous structure in the time period from t-2s to t+2s are both less than or equal to 20%, it is considered that the aircraft is in a stable thermal environment state at the current time.

[0018] Furthermore, in step S2, when the aerodynamic heat flux Q on the outside of the porous structure, the aerodynamic pressure P1 on the outside of the porous structure, and the pressure P2 in the inner cavity of the porous structure are known, Q, P1, and P2 are used as boundary conditions to comprehensively solve the control equations of velocity and density, the Kays model of sweating heat flux, and the control equation of temperature to obtain the supply flow rate q of the sweating agent corresponding to the porous structure surface temperature control target T_goal.

[0019] Furthermore, the governing equations for velocity and density are:

[0020]

[0021] p=ρR g T

[0022]

[0023] The Kays model of sweating and heat flow reduction is:

[0024]

[0025] The governing equation for temperature is:

[0026]

[0027] Where R is the ratio of the net heat flow of sweating to the heat flow without sweating, F is the dimensionless outflow rate of the local sweating agent, St0 is the heat transfer Stanton number when there is no sweating; t,ρ, p, T,c p , S are time, density, speed, pressure, external force, temperature, specific heat, and heat source, respectively. The subscripts s and f represent solid and fluid, and ε p ,μ,K D ,K F ,k eff They are porosity, viscosity, Darcy permeability, Forchheimer permeability, and effective thermal conductivity, is the unit matrix; ▽ is the Laplace mathematical operator, R g is the ideal gas constant.

[0028] Q is used as the outer boundary condition of the control equation of temperature, and P1 and P2 are used as the inner and outer pressure boundary conditions of the control equation of velocity and density to obtain the sweating agent flow rate q.

[0029] T in the above temperature control equation s That is, the temperature T of the porous structure. The present invention reduces the temperature of the structure by controlling the flow rate of the sweating agent. In the calculation equation, one flow rate value corresponds to one T s Value; when T sWhen the value reaches T_goal, the flow value obtained is the desired one.

[0030] Furthermore, in step S3, the electronic control system pre-stores the pneumatic heat flow Q outside the porous structure and the pneumatic pressure P1 outside the porous structure at the next moment;

[0031] When Q or P1 increases at the next moment, the diaphoretic flow rate and pressure are increased in advance; when it is predicted that Q or P1 will decrease, the diaphoretic flow rate and pressure are reduced in advance.

[0032] Furthermore, when executing step S2 and step S3, when the temperature T of the porous structure is greater than or equal to the upper limit of the preset optimal temperature range, the diaphoretic agent supply flow rate is increased based on the original diaphoretic agent supply conditions until the temperature T of the porous structure drops to the lower limit of the optimal temperature range, and the original diaphoretic agent supply conditions are restored.

[0033] Furthermore, the upper limit of the optimal temperature range is determined according to the service temperature of the porous structural material and the engineering design safety factor;

[0034] The increased diaphoretic supply flow rate based on the original diaphoretic supply conditions is recorded as the diaphoretic supply increment, and the optimal temperature range satisfies the following conditions:

[0035] The period during which the temperature of the porous structure gradually decreases from the upper limit of the optimal temperature interval to the lower limit of the optimal temperature interval under the action of the sweating agent supply increment, and then the sweating agent supply increment decreases to zero and the temperature of the porous structure gradually increases from the lower limit of the optimal temperature interval to the upper limit of the optimal temperature interval is regarded as a cycle;

[0036] In a periodic time period, the method for determining the lower limit of the optimal temperature interval is that its value can minimize the full-cycle time average of the increase in the supply of the perspiration agent.

[0037] Furthermore, a multi-objective optimization method is used to obtain the lower limit value of the optimal temperature range under given aerodynamic heat flux and aerodynamic pressure boundary conditions, and simultaneously determine the incremental value of the diaphoretic supply.

[0038] Furthermore, the pore structure surface temperature control target T_goal takes the upper limit value of the optimal temperature range.

[0039] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0040] (1) The present invention provides a gas-phase sweat cooling thermal protection system with adaptive flow control, which can sense the three degrees of freedom of heat flow, pressure and structural temperature outside the structure in real time, laying a foundation for meeting the thermal protection requirements of aircraft with lower mass compensation;

[0041] (2) The present invention provides a gas-phase transpiration cooling thermal protection method with flow adaptive control, which takes into account various conditions of stable and unstable flight of the aircraft, and achieves the purpose of saving transpiration agent on the basis of achieving a stable thermal protection effect;

[0042] (3) The present invention obtains the control target of the optimal temperature range based on a multi-objective optimization method, further avoids the waste of the diaphoretic agent by regulating the diaphoretic agent flow supply increment, and effectively improves the engineering application efficiency of the diaphoretic agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of a gas phase sweating cooling thermal protection system with flow adaptive control according to the present invention. DETAILED DESCRIPTION

[0044] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0045] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0046] Gas-phase transpiration cooling technology has significant advantages in thermal protection performance. In response to time-varying thermal environment characteristics, the traditional step-type transpiration agent flow supply strategy will result in a waste of transpiration agent mass and increase the compensation of the entire system. The present invention perceives the three degrees of freedom of heat flow, pressure and structural temperature on the outside of the structure in real time, faces the constant or time-varying external thermal environment and structural temperature response characteristics, takes the maximum temperature of the structure as the basic constraint, and takes reducing the transpiration agent mass compensation as the core goal. The control method of the pressure control device is given by adopting the idea of ​​"real-time feedback control of net heat flow, real-time monitoring and regulation of structural temperature, and early supply cut-off in the face of low back pressure". The new scheme can meet the thermal protection needs of the aircraft with lower mass compensation.

[0047] The present invention provides an engineering control technology solution for sweat cooling.

[0048] Aircraft flying at high speeds will encounter the problem of aerodynamic heating, which will cause the temperature of the structure to rise and exceed the material limit. Transpiration cooling technology is an efficient thermal protection technology that protects the structural safety of high-speed aircraft during flight.

[0049] The principle of the sweating cooling technology is to design the outer shell structure into a porous structure so that the sweating agent can flow out from the inside to the outside through the porous structure. When the sweating agent flows out of the porous structure at a certain flow rate, it can directly reduce the aerodynamic heating heat flow and form a protection for the aircraft shell structure; at the same time, when the sweating agent flows in the heated and heated porous structure, it can also take away the heat of the porous structure in the form of convection, reduce the temperature of the porous structure, and form a second protection mechanism for the aircraft shell structure.

[0050] The invention discloses a flow adaptively controlled gas phase sweating cooling thermal protection system, comprising a porous structure, a dense material structure, a porous structure inner cavity, a sweating agent supply pipeline, a pressure regulating device, a sweating agent gas source and an electronic control system. The present invention also discloses a gas-phase sweating cooling thermal protection method with flow adaptive control, including judging the flight thermal environment state of the aircraft, when the aircraft is in a stable thermal environment state, determining the sweating agent flow rate q supplied by the sweating agent source according to the aerodynamic heat flow Q outside the porous structure, the aerodynamic pressure P1 outside the porous structure and the pressure P2 inside the porous structure; in an unstable thermal environment state, predicting the changes of Q and P1 outside the porous structure at the next moment, and adjusting the sweating agent flow rate q supplied by the sweating agent source in advance according to the prediction result; at the same time, in the stable and unstable thermal environment states, monitoring the temperature T of the porous structure, when T rises above the upper limit of the optimal temperature range, starting the sweating agent flow rate increment until T drops to the lower limit of the optimal temperature range; the method for determining the lower limit of the optimal temperature range is to ensure that the average time consumption rate of the sweating agent flow rate is the lowest through a multi-objective optimization method. The present invention can efficiently meet the requirements of aerodynamic thermal protection with a lower sweating agent flow rate demand, and has broad application prospects in the field of aerodynamic thermal protection technology.

[0051] like Figure 1 The present invention provides a gas-phase sweating cooling thermal protection system with adaptive flow control, comprising a porous structure 1, a dense material structure 2, a porous structure inner cavity 3, a sweating agent supply pipeline 4, a pressure regulating device 5, a sweating agent gas source 6, and an electronic control system 7. The electronic control system 7 stores the state parameters of the thermal environment and the aerodynamic pressure at different times, and can measure the porous structure temperature and inner cavity pressure in real time. The electronic control system 7 realizes the perception of the heat flow outside the porous structure, the outer pressure, and the structural temperature by three methods: comprehensive retrieval of pre-stored data, measurement of real-time data, and rapid iterative calculation. The dense material structure 2 is close to the outer side of the aircraft shell, and the porous structure 1 is located outside the dense material structure 2.

[0052] The present invention also provides a gas phase sweating cooling heat protection method with flow adaptive control, which specifically includes:

[0053] When the aircraft is flying stably, the aerodynamic heating heat flow and aerodynamic pressure on the outer surface of the porous structure are relatively stable. At this time, the flow rate of the sweating agent can be controlled at a stable level to achieve a stable thermal protection effect.

[0054] In this state, the method for calculating and determining the perspiration agent flow rate is:

[0055] Equation 1:

[0056]

[0057] p=ρR g T

[0058]

[0059] Equation 2:

[0060]

[0061] Equation 3:

[0062]

[0063] Equation group 1 is the control equation of velocity and density, which describes the flow process of the sweating agent in the porous shell structure. Under the conditions of known inner pressure and outer pressure, the outflow rate and distribution of the sweating agent on the outer surface of the porous shell can be solved.

[0064] Equation group 2 is the Kays model for calculating the heat flow reduction of sweating, which describes the heat flow reduction process of the sweating agent induced outflow. By knowing the outflow flow distribution of the sweating agent and the heat flow distribution on the surface of the structure when there is no sweating, the net heat flow and its distribution on the surface of the structure when the sweating agent is outflowing can be obtained. In the formula, R is the ratio of the net heat flow of sweating to the heat flow without sweating, and F is the dimensionless outflow flow of the local sweating agent.

[0065] Equation group 3 is the governing equation for temperature, which describes the heat transfer process between the porous structure and the internal flowing diaphoretic agent. By knowing the outer net heat flow boundary condition, the outflow temperature and distribution of the diaphoretic agent on the outer surface of the porous shell can be solved, and the temperature field of the porous shell can be solved.

[0066] The symbols of the three equations all use the common engineering symbols.

[0067] By comprehensively solving equations 1, 2, and 3, and taking the aerodynamic heat flux Q outside the porous structure 1 and the aerodynamic pressure P1 outside the porous structure 1 as the boundary conditions of the equations, the supply perspiration agent flow rate q corresponding to the porous structure surface temperature control target T_goal can be obtained.

[0068] The porous structure surface temperature control target T_goal should be within the optimal temperature range described below; preferably, its value can be selected as the upper limit of the optimal temperature range.

[0069] When the aircraft experiences non-stable conditions such as large acceleration and attitude changes, the aerodynamic heating heat flow and aerodynamic pressure on the outer surface of the porous structure will also change significantly. The technical solution for sweating cooling control in this changing state is as follows:

[0070] Action is taken in advance based on the predicted information of aerodynamic heat flow and aerodynamic pressure. When the aerodynamic heat flow is predicted to increase, the diaphoretic flow rate is increased in advance to improve the thermal stability; when the aerodynamic heat flow is predicted to decrease, the diaphoretic flow rate is reduced in advance to save the amount of diaphoretic. When the aerodynamic pressure is predicted to increase, the diaphoretic supply pressure is increased in advance to avoid the problem of short-term insufficient diaphoretic supply after the aerodynamic pressure increases; when the aerodynamic pressure is predicted to decrease, the diaphoretic supply pressure is reduced in advance to make full use of the residual pressure release in the diaphoretic cavity to achieve the purpose of saving diaphoretic.

[0071] The prediction information of aerodynamic heat flow and aerodynamic pressure comes from the retrieval of pre-stored data. The calculation and control module pre-stores the database information of the aircraft's trajectory, flight attitude, time, and the distribution data information of aerodynamic heat flow and aerodynamic pressure. During the flight, real-time data values ​​can be obtained through retrieval calculation. In this way, the prediction of aerodynamic heat flow and aerodynamic pressure can be realized.

[0072] During the control process under the aforementioned stable and unstable states, the temperature of the key position of the porous structure is measured synchronously and in real time. The key position may be the highest temperature position, the weak structure temperature point, etc. The temperature T of the porous structure 1 measured in real time by the electronic control system 7 is the temperature of the key position. Transpiration cooling can reduce the heat flow by a certain proportion, but it cannot completely reduce the aerodynamic heat flow to zero. Therefore, under the action of the net heat flow after sweating, the temperature of the porous structure continues to increase. At this time, by measuring the temperature of the structure in real time, when the peak value of the measured structure temperature reaches the upper limit of the "optimal temperature interval", the flow supply is increased on the basis of the original diaphoretic supply conditions, that is, the diaphoretic flow supply increment is started to realize the cooling control of the structure until the temperature peak drops to the lower limit of the optimal temperature interval, and the diaphoretic flow supply increment is stopped.

[0073] Here, a new concept of "optimal temperature control range" is introduced: although transpiration cooling can reduce the temperature of the structure, the temperature control target is too low, which is not conducive to the radiation heat dissipation capacity of the outer surface of the structure (radiation heat flux is a function of the fourth power of the surface temperature. The lower the surface temperature, the lower the radiation heat dissipation capacity), resulting in a waste of transpiration agent. Therefore, a maximum temperature control range is needed to avoid the waste of transpiration agent.

[0074] The upper limit of the interval is determined by combining the service temperature of the material and taking into account the designer's engineering design safety factor; the lower limit of the interval is determined in that the maximum temperature of the structure gradually decreases from the upper limit of the interval to the lower limit of the interval under the action of the sweating agent supply increment, and then the sweating agent supply increment drops to zero, and the structure temperature gradually rises from the lower limit of the interval to the upper limit of the interval. In this periodic time period, the time-averaged value of the sweating agent supply increment is the smallest. At this time, the lower limit of the interval is the optimal lower limit of the interval. The lower limit of the interval and the upper limit of the interval together constitute the optimal temperature control interval.

[0075] The calculation and determination of the perspiration agent flow supply increment is simultaneously calculated and determined in the calculation process of the lower limit of the aforementioned "optimal temperature control interval". It is essentially a multi-objective optimization problem under given aerodynamic heat flow and aerodynamic pressure boundary conditions. The result data set can be obtained in advance by parallel calculation using high-performance computers and pre-stored in the form of a database for real-time query and retrieval.

[0076] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0077] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A gas phase sweating cooling thermal protection system with flow adaptive control, characterized in that: include: A porous structure (1), a dense material structure (2), an inner cavity of the porous structure (3), a diaphoretic agent supply pipeline (4), a pressure regulating device (5), a diaphoretic agent gas source (6) and an electronic control system (7); The dense material structure (2) and the porous structure (1) are combined to form a hollow structure, and the internal cavity of the hollow structure is the porous structure inner cavity (3); A diaphoretic gas source (6) located outside the porous structure inner cavity (3) is connected to the porous structure inner cavity (3) via a diaphoretic supply pipeline (4), and the diaphoretic gas source (6) is used to supply diaphoretic agent to the porous structure inner cavity (3); A pressure regulating device (5) is provided on the diaphoretic agent supply pipeline (4); The electronic control system (7) pre-stores aircraft status data, and obtains the aerodynamic heat flow Q outside the porous structure (1) and the aerodynamic pressure P1 outside the porous structure (1) by real-time querying the MAP diagram of the pre-stored aircraft status data; the electronic control system (7) simultaneously measures the temperature T of the porous structure (1) and the pressure P2 of the inner cavity (3) of the porous structure in real time, and controls the pressure regulating device (5) according to the temperature T of the porous structure (1), the pressure P2 of the inner cavity (3) of the porous structure, the aerodynamic heat flow Q outside the porous structure (1) and the aerodynamic pressure P1 outside the porous structure (1), thereby achieving real-time control of the flow rate q of the diaphoretic agent supplied by the diaphoretic agent gas source (6).

2. A gas phase sweating cooling heat protection method with flow adaptive control, characterized in that: The method is implemented by using a gas phase sweating cooling thermal protection system with flow adaptive control as claimed in claim 1, comprising: S1 determines the thermal environment state of the aircraft. If the aircraft is in a stable thermal environment state, proceed to step S2; otherwise, proceed to step S3; The S2 electronic control system (7) determines the flow rate q of the diaphoretic agent supplied by the diaphoretic agent source (6) according to the temperature T of the porous structure (1), the pneumatic heat flow Q outside the porous structure (1), the pneumatic pressure P1 outside the porous structure (1), the pressure P2 of the inner cavity (3) of the porous structure, and the temperature control target T_goal of the porous structure set in advance; The S3 electronic control system (7) predicts the changes in the pneumatic heat flow Q and the pneumatic pressure P1 outside the porous structure (1) at the next moment, and adjusts the diaphoretic gas source (6) to supply the diaphoretic flow rate q in advance according to the predicted results.

3. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 2, characterized in that: In step S1, the method for determining whether the aircraft is in a stable thermal environment state includes: The current moment is set as t. When the change rates of the aerodynamic heat flux Q outside the porous structure (1) and the aerodynamic pressure P1 outside the porous structure (1) in the time period from t-2s to t+2s are both less than or equal to 20%, it is considered that the aircraft is in a stable thermal environment state at the current moment.

4. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 2, characterized in that: In step S2, when the aerodynamic heat flux Q on the outside of the porous structure (1), the aerodynamic pressure P1 on the outside of the porous structure (1), and the pressure P2 in the inner cavity (3) of the porous structure are known, Q, P1 and P2 are used as boundary conditions to comprehensively solve the control equations of velocity and density, the Kays model of sweating heat flux and the control equation of temperature to obtain the supply sweating agent flow rate q corresponding to the porous structure surface temperature control target T_goal.

5. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 4, characterized in that: The governing equations for velocity and density are: p6ρR g T The Kays model of sweating and heat flow reduction is: The governing equation for temperature is: Where R is the ratio of the net heat flow of sweating to the heat flow without sweating, F is the dimensionless outflow rate of the local sweating agent, St0 is the heat transfer Stanton number when there is no sweating; t,ρ, p, T,c p , S are time, density, speed, pressure, external force, temperature, specific heat, and heat source, respectively. The subscripts s and f represent solid and fluid, and ε p ,μ,K D ,K F ,k eff They are porosity, viscosity, Darcy permeability, Forchheimer permeability, and effective thermal conductivity, is the identity matrix; is the Laplace operator, R g is the ideal gas constant; Using Q as the outer boundary condition of the temperature control equation, and using P1 and P2 as the inner and outer pressure boundary conditions of the velocity and density control equations, the perspiration agent flow rate q corresponding to the porous structure surface temperature control target T_goal is obtained.

6. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 2, characterized in that: In step S3, the electronic control system (7) pre-stores the pneumatic heat flow Q outside the porous structure (1) and the pneumatic pressure P1 outside the porous structure (1) at the next moment; When Q or P1 increases at the next moment, the diaphoretic flow rate is increased in advance; when it is predicted that Q or P1 will decrease, the diaphoretic flow rate is reduced in advance.

7. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 4, characterized in that: When executing step S2 and step S3, when the temperature T of the porous structure (1) is greater than or equal to the upper limit of the preset optimal temperature range, the diaphoretic agent supply flow rate is increased based on the original diaphoretic agent supply conditions until the temperature T of the porous structure (1) drops to the lower limit of the optimal temperature range, thereby restoring the original diaphoretic agent supply conditions.

8. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 7, characterized in that: The upper limit of the optimal temperature range is determined according to the service temperature of the porous structural material and the engineering design safety factor; The increased diaphoretic supply flow rate based on the original diaphoretic supply conditions is recorded as the diaphoretic supply increment, and the optimal temperature range satisfies the following conditions: The period during which the temperature of the porous structure (1) gradually decreases from the upper limit of the optimal temperature interval to the lower limit of the optimal temperature interval under the action of the sweating agent supply increment, and then the sweating agent supply increment decreases to zero and the temperature of the porous structure (1) gradually increases from the lower limit of the optimal temperature interval to the upper limit of the optimal temperature interval is regarded as a cycle; In a periodic time period, the method for determining the lower limit of the optimal temperature interval is that its value can minimize the full-cycle time average of the increase in the supply of the perspiration agent.

9. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 8, characterized in that: A multi-objective optimization method is used to obtain the lower limit of the optimal temperature range under given aerodynamic heat flux and aerodynamic pressure boundary conditions, and simultaneously determine the incremental value of the diaphoretic supply.

10. The method for heat protection of gas phase sweating cooling with adaptive flow control according to claim 9, characterized in that: The porous structure surface temperature control target T_goal takes the upper limit of the optimal temperature range.

Images