Multi-scale full-coupling transient prediction method for porous interface phase change sweating cooling effect

Abstract

The invention relates to a multi-scale full-coupling transient prediction method for a porous interface phase change sweating cooling effect, and belongs to the technical field of thermal protection of a leading edge end material of a hypersonic aircraft. The problems that in aircraft phase change sweating cooling numerical simulation in the prior art, phase change porous interface full coupling information is lost, and heat and drag reduction effect prediction is not accurate are solved. The method comprises the following steps: determining physical parameters, boundary conditions and initial conditions of a porous interface; constructing a porous interface phase change sweating full-coupling model; obtaining a predicted porous interface phase change sweating multi-physical field based on a porous interface phase change sweating full coupling model; and based on the porous interface phase change sweating multi-physical field, the cooling efficiency of a porous interface phase change sweating blowing area and a blowing trailing edge area, the porous interface phase change sweating transient blowing ratio, the total consumption of a coolant and the porous interface phase change sweating friction resistance reduction effect are obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal protection of leading edge end materials of hypersonic aircraft, and specifically relates to a multi-scale fully coupled transient prediction method for porous interface phase change sweating cooling effect, and in particular to a multi-scale fully coupled transient prediction method for high enthalpy porous interface phase change sweating cooling effect. Background Art

[0002] The advance prediction of product material properties, environmental conditions, etc. can reduce R&D costs and time, optimize material design and processing technology, and improve product quality and safety. This is particularly important in the aerospace field.

[0003] During the re-entry phase of a spacecraft, the cruising phase of a high-speed vehicle, and the operation of a rocket engine nozzle, key components are usually faced with significant high aerodynamic heat loads and the resulting material degradation problem. Therefore, as an efficient active thermal management method, transpiration cooling technology, especially phase change transpiration cooling using liquid coolants that can undergo phase change, has aroused widespread research interest in recent years. Studies have shown that this technology has flexible coolant control, efficient surface protection, and the potential to reduce the friction of the vehicle surface.

[0004] In the application of thermal protection system, the air outside the aircraft is high-speed flow, and its Mach number is usually greater than 5; the temperature near the wall of the hot air channel area (the wall of the porous interface close to the leading edge of the aircraft) is usually high, up to 2000K. Therefore, the coupled prediction of the phase change sweating cooling effect of the porous interface under the environment of external high-speed multi-phase, multi-component flow and low-speed multi-phase, multi-component flow inside the porous medium is difficult to achieve. Some studies have tried to overcome the difficulties of numerical simulation of phase change sweating cooling by adding assumptions to simplify mathematical models, regional decoupling, iterative coupling and other methods, such as difficulties in high-speed two-phase flow simulation, heat and mass transfer modeling at the interface, and variable updating between free flow and porous areas, and reasonably analyze the thermal protection effect based on the calculation results. For example, the method of simulating the porous medium area separately can be used to reasonably predict the interface heat flow to predict the thermal protection effect under different working conditions; the multi-region iterative coupling strategy can be used to transfer heat flux density and temperature in both directions through the interface for iterative solution. However, these studies mainly considered the heat transfer at the interface, but ignored the mass transfer of air and water vapor at the interface and the related shear stress. Therefore, the two-way interaction between the external air and the fluid inside the porous region, such as air intrusion, convection, mixing, and outflow of air and water vapor, cannot be taken into account. At the same time, under the assumption of continuous scale of porous media, the interface pore scale information is not available. In addition, the iterative coupling method can only obtain a steady-state solution, but the key transient information is missing. Therefore, for the high-enthalpy porous interface phase change sweating, a fully coupled numerical simulation method is urgently needed to predict the transient heat reduction and drag reduction effects. Summary of the invention

[0005] In view of the above problems, the present invention provides a multi-scale fully coupled transient prediction method for the phase change sweating cooling effect of porous interfaces, which solves the problems of missing phase change porous interface fully coupled information and inaccurate prediction of heat reduction and drag reduction effect in the prior art of aircraft phase change sweating cooling effect prediction. Firstly, based on DuMu x The platform is used to improve and establish a numerical model to realize the calculation of bidirectional coupling of phase change porous interface under given pore structure, incoming flow conditions and coolant conditions; at the same time, by analyzing the calculation results, the transient cooling efficiency, transient blowing ratio, total coolant consumption over a period of time and reduction effect of near-wall friction resistance of the phase change porous interface under given pore structure, incoming flow conditions and coolant conditions are obtained, which is of great significance in the comprehensive performance evaluation of phase change sweating cooling and the pore structure design of porous media, and provides technical support for the mechanism research and engineering design of sweating cooling.

[0006] The present invention provides a multi-scale fully coupled transient prediction method for porous interface phase change sweating cooling effect, and the specific steps are as follows: Step 1, determining the physical models of the hot air channel region and the porous medium region of the porous interface; Step 2, determining the boundary conditions and initial conditions of the hot air channel area and the porous medium area; Step 3, based on the physical models of the hot air channel region and the porous medium region in step 1, and the boundary conditions and initial conditions in step 2, a fully coupled model of porous interface phase change sweating is constructed; Step 4, inputting the physical model of the porous interface to be measured, the boundary conditions and initial conditions of the hot air channel area and the coolant inlet, and the time step and total time length of the transient calculation into the fully coupled model based on the porous interface phase change sweating to obtain the predicted porous interface phase change sweating multi-physical field; Step 5, based on the porous interface phase change sweating multi-physics field, obtain the cooling efficiency of the porous interface phase change sweating blowing area and the blowing trailing edge area; Step 6, based on the porous interface phase change sweating multi-physics field, obtain the porous interface phase change sweating transient blowing ratio and the total coolant consumption; Step 7, based on the porous interface phase change sweating multi-physics field, obtain the porous interface phase change sweating friction reduction effect.

[0007] Optionally, the physical parameters of the hot air channel area include the length, height, width and number of grid nodes in each section of the hot air channel; the physical parameters of the porous medium area include the number of pores, the shape of the pores, the shape of the pore throat section, the size of the radius of the inscribed sphere in the pore body and the size of the radius of the inscribed circle in the pore throat section.

[0008] Optionally, the boundary conditions of the hot air channel area include a simulation reference pressure, a hot air channel inlet and outlet pressure difference, a hot air channel inlet temperature, and a hot air channel inlet air concentration; For the porous medium region, the boundary conditions are the boundary conditions of coolant supply, which include the coolant inlet liquid phase pressure and coolant inlet temperature, coolant inlet liquid content and coolant inlet component fugacity; The initial conditions include the initial temperature, initial pressure, initial velocity and initial component distribution in the hot air channel area; the initial water level, initial temperature, initial pressure and initial component distribution in the porous medium area.

[0009] Optionally, the specific steps of constructing the fully coupled model of porous interface phase change sweating in step 3 are: Establish the governing equations of the hot air channel region under the finite volume method and the governing equations of the porous medium region under the fully coupled model of porous interface phase change sweating, as well as the constitutive relations of the fully coupled model of two-phase flow in porous media and porous interface phase change sweating; Based on the interface coupling conditions of the hot air channel region and the porous medium region, and the boundary conditions of the channel hot air inlet and outlet and the coolant inlet; the control equations, constitutive relations, the boundary conditions and initial conditions of the hot air channel region and the coolant inlet are assembled to obtain a large matrix equation; the large matrix equation is iteratively solved to obtain a multi-scale fully coupled transient solution code; The multi-scale fully coupled transient solution code is compiled to obtain a porous interface phase change sweating fully coupled model of porous interface phase change sweating cooling effect.

[0010] Optionally, the obtained predicted porous interface phase change sweating multi-physics field includes predicted hot air channel bottom temperature, predicted coolant inlet mass flux, predicted hot air channel inlet mass flux, gradient distribution at the interface between the hot air channel and the porous medium region, and mixed gas dynamic viscosity distribution at the interface between the hot air channel and the porous medium region.

[0011] Optionally, the cooling efficiency of the porous interface phase change sweat blowing area and the blowing trailing edge area in step 5 is expressed as:

[0012] in, Indicates cooling efficiency; T∞ , T and Tc They are respectively the predicted hot air inlet temperature, the predicted hot air channel bottom temperature and the predicted coolant inlet temperature.

[0013] Optionally, in step 6, the porous interface phase change sweating transient blowing ratio BR The expression is:

[0014] in, ρcUc represents the predicted coolant inlet mass flux; ρhUh represents the predicted mass flux at the hot air channel inlet; Indicates the coolant inlet location; Indicates the location of the hot air channel inlet.

[0015] Optionally, the total consumption of the porous interface phase change sweat coolant The expression is:

[0016] in, Ttotal is the total cooling time; ρcUc represents the predicted coolant inlet mass flux; ρhUh represents the predicted mass flux at the hot air channel inlet; Indicates the coolant inlet location.

[0017] Optionally, in step 7, the porous interface phase change sweating friction reduction effect Cf The expression is:

[0018] in, is the dynamic viscosity distribution of the mixed gas at the interface between the hot air channel and the porous medium area, The gas at the bottom wall of the hot air channel x The component of the directional velocity, is the mainstream density of the hot air channel air; represents the coefficient of surface friction; Indicates the hot air channel area y Direction coordinates; Indicates the bottom wall position of the hot air channel; Indicates the mainstream position of air in the hot air channel area.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The multi-scale fully coupled transient prediction method of the present invention is a multi-scale fully coupled method, in which a phase change dynamic pore network model is used to model the porous medium area under a preset local thermal equilibrium, a finite volume method is used to model the hot air channel area, and their discrete equations are installed in the same matrix to achieve fully coupled calculations, successfully simulating the high enthalpy phase change porous interface of sweat cooling.

[0020] 2. The multi-scale fully coupled transient prediction method of the present invention can capture the phase change process caused by the intrusion and temperature rise of external hot air in porous media, the wetting of liquid water in porous interfaces, and the transient evolution of the external cooling film caused by the convective mixing of free-flow air and water vapor on the interface.

[0021] 3. The multi-scale fully coupled transient prediction method of the present invention can analyze the cooling efficiency of the blowing area and the blowing trailing edge area of ​​the sweating porous interface, the transient blowing ratio and total coolant consumption of the sweating porous interface, and the friction reduction effect of the sweating porous interface for specific pore structures, boundary conditions and initial conditions, thereby improving the accuracy of the prediction results.

[0022] 4. The multi-scale fully coupled transient prediction method of the present invention can be applied to hypersonic aircraft, especially aircraft with a Mach number greater than 5, whose surface enthalpy value can be greater than 1MJ, that is, it constitutes a multi-scale fully coupled transient prediction method for high-enthalpy porous interface phase change sweating cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0024] Figure 1 A flow chart of constructing a fully coupled model of porous interface phase change sweating for the multi-scale fully coupled transient prediction method of the present invention; Figure 2 A schematic diagram of the physical model, boundary conditions and initial conditions of the multi-scale fully coupled transient prediction method of the present invention; Figure 3 The cooling efficiency result diagram of the sweating porous interface blowing area and the blowing trailing edge area in the embodiment of the present invention; Figure 4 This is a result diagram of transient blowing ratio of the sweating porous interface in an embodiment of the present invention; Figure 5 This is a diagram showing the effect of reducing friction on the sweating porous interface in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0026] A specific embodiment of the present invention, as Figure 1-Figure 5 , discloses a multi-scale fully coupled transient prediction method for the porous interface phase change sweating cooling effect, the specific steps are as follows: Step 1: Determine the physical model of the porous interface.

[0027] Specifically, the physical model of the porous interface includes the hot air channel region and the porous medium region; the physical parameters of the hot air channel region include the hot air channel length, height, width and the number of grid nodes in each segment; the physical parameters of the porous medium region include the number of pores, pore body shape, pore throat cross-sectional shape, the size of the pore body inscribed sphere radius and the size of the pore throat cross-sectional inscribed circle radius.

[0028] Furthermore, the physical parameters defined on each grid segment in the hot air channel area are solved by the finite volume method.

[0029] Step 2: Determine the boundary conditions and initial conditions of the hot air channel area and the porous medium area.

[0030] Specifically, the boundary conditions of the hot air channel area include the simulation reference pressure, the hot air channel inlet and outlet pressure difference, the hot air channel inlet temperature and the hot air channel inlet air concentration; For the porous medium region, the boundary conditions are the boundary conditions of coolant supply, which include the coolant inlet liquid phase pressure and coolant inlet temperature, coolant inlet liquid content and coolant inlet component fugacity.

[0031] The initial conditions include the initial temperature, initial pressure, initial velocity and initial component distribution in the hot air channel area; the initial water level, initial temperature, initial pressure and initial component distribution in the porous medium area.

[0032] It can be understood that the initial water level height of the porous medium region is a water level height set in the initial state of the simulation, thereby starting the simulation.

[0033] Step 3: Construct a fully coupled model of porous interface phase change sweating.

[0034] Optionally, establish the control equations of the hot air channel region under the finite volume method and the control equations of the porous medium region under the porous interface phase change sweating full coupling model, the constitutive relationship of the two-phase flow in the porous medium and the porous interface phase change sweating full coupling model; based on the interface coupling conditions of the hot air channel region and the porous medium region, the boundary conditions and initial conditions of the channel hot air inlet and outlet and the coolant inlet; use the DuMux platform The control equations, constitutive relations, boundary conditions and initial conditions of the hot air channel area and the coolant inlet are assembled to obtain a large matrix equation; the large matrix equation is iteratively solved to obtain a multi-scale fully coupled transient solution code to achieve a multi-scale fully coupled transient solution; finally, CMake is used to compile the above multi-scale fully coupled transient solution code under the Ubuntu system to obtain a porous interface phase change sweating fully coupled model (i.e., a multi-scale fully coupled transient solver) of the porous interface phase change sweating cooling effect.

[0035] Exemplarily, the porous interface phase change sweating fully coupled model solver of the porous interface phase change sweating cooling effect is used to predict the temperature, velocity, pressure, mole fraction of water vapor, etc. in the hot air channel area; the liquid phase volume fraction, liquid phase pressure, gas phase pressure, mole fraction of air, etc. in the porous medium area.

[0036] The porous interface phase change sweating fully coupled model of the present invention can be applied to hypersonic aircraft, and its surface enthalpy value can be greater than 1MJ, that is, it constitutes a porous interface phase change sweating fully coupled model of high enthalpy porous interface phase change sweating cooling effect.

[0037] Specifically, the governing equations of the hot air channel region under the finite volume method include the momentum equation, the component transport equation and the energy equation; the governing equations of the porous medium region under the phase change dynamic pore network model include the momentum equation, the component transport equation and the energy equation.

[0038] Understandably, see Figure 2 The hot air channel area includes a hot air channel inlet, a hot air channel and a hot air channel outlet; the hot air channel area is located at the outer wall surface of the device where the porous medium area is arranged; and the coolant inlet is arranged on the inner side of the porous medium area.

[0039] Exemplarily, the porous interface is disposed at the leading edge end of the aircraft (ie, the sweat blowing area).

[0040] See also Figure 1 The fully coupled model of porous interface phase change sweating cooling effect is solved. At the beginning of the solution process, the initial fields of the two regions (i.e., the hot air channel region and the porous medium region) are obtained according to the set conditions, including the temperature in the hot air channel region. ,pressure and the mole fraction of air ,in, k ∈water, air, and the temperature in the porous media region TPNM , Liquid pressure , Liquid saturation and the mole fraction of air . Secondly, the transient simulation is advanced at the specified time step. Then, all discrete equations are assembled into a large linear system under the coupling manager framework and solved simultaneously by Newton's method iteration; next, the liquid saturation in the throat is updated under the updated primary variable Distribution status, determine the hydraulic conductivity of the new throat (in, α ∈ l , g ) for further simulation; Newton iterations are performed at each time step until the residual is less than 10-6.

[0041] Furthermore, the momentum equation of the hot air channel region is:

[0042] in, , , , and are the density, velocity, dynamic viscosity, shear tensor and pressure of the fluid in the hot air channel region, respectively; is the three-dimensional equivalent volume force; Indicates the current time.

[0043] Furthermore, the component transport equation in the hot air channel region is:

[0044] in, k Represents the components in the environment where the aircraft is located k The components of the aircraft environment are water vapor air and air water. k ∈water,air; , , and For components k The mole fraction, molar mass, mass fraction and diffusion coefficient of . Furthermore, the energy equation of the hot air channel area is:

[0045] in, , , and are the thermal conductivity, temperature, specific internal energy and specific enthalpy of the gas in the hot air channel area, respectively.

[0046] Furthermore, the momentum equation in the porous medium region is:

[0047] in, k Represents the components in the environment where the aircraft is located k , the components of the aircraft's environment are water vapor air and air water; Yes α In the throat ij Traffic volume; Yes α In the throat ij The hydraulic conductivity of Yes α In the i The pressure of each pore; Yes α In the j The pressure of each pore; α ∈ g , l ( g For gas phase and l is liquid phase), ij For connecting hole i and pore body j The throat.

[0048] Further, α In the throat ij The average flow rate The expression is:

[0049] in, Yes α In the throat ij flow cross-sectional area.

[0050] It is understood that the pores are pores in the porous medium region.

[0051] Furthermore, the component transport equation in the porous medium region is:

[0052] in, Indicates the volume of the pore; It is a component k In the phase α The mole fraction in the table Show components k The molar mass of Indicates the phase in the pore α density; Yes α Volume fraction of Indicates phase α Flow rate in the throat; It is a component k In the phase α Medium diffusion mass flux; Indicates phase α The size of the flow cross-sectional area; Represents the components at the interface between the two regions (hot air channel region and porous medium region) k The quality source term.

[0053] Furthermore, under the preset local thermal equilibrium, the energy equation of the porous medium region is:

[0054] in, V i It is i The volume of a pore; , , and is the specific heat of the skeleton material in the porous medium region, i Porous phase α The thermal conductivity, j Porous phase α The thermal conductivity of the material and the thermal conductivity of the skeleton material; ε It represents the porosity, which indicates the volume of all pores and their proportion in the overall porous medium volume; Yes α Volume fraction of Indicates phase α Specific internal energy; Indicates the density of the skeleton material; represents the temperature in the porous medium region; Indicates hole body i The temperature inside; Indicates hole body j The temperature inside; Indicates phase α The specific enthalpy of Indicates phase α Flow rate in the throat; Indicates components k In the phase α Specific internal energy in; represents the energy source term at the interface between the two regions; Indicates phase α In the throat ij The size of the flow cross-sectional area; Indicates throat ij The length of the size.

[0055] Furthermore, the constitutive relations of the fully coupled model of two-phase flow in porous media and phase change sweating at porous interfaces are used to solve the governing equations in the above-mentioned porous media region.

[0056] Specifically, the constitutive relations of the fully coupled model of two-phase flow in porous media and phase change at porous interfaces include the liquid pressure in the porous media , gas phase pressure and liquid volume fraction relationship.

[0057] Furthermore, the liquid phase pressure in the pores of the porous medium is determined according to Laplace's law. , gas phase pressure and liquid volume fraction The relationship is expressed as:

[0058] in, and are the liquid phase pressure and gas phase pressure of the pore body respectively; Indicates the capillary pressure of the pore body (capillary pressure refers to the additional pressure on the curved surface of the capillary (here, the pore body) caused by the rise or fall of the liquid level); Indicates liquid phase l volume fraction.

[0059] The liquid phase in the porous medium region l Capillary pressure The expression is:

[0060] in, , and are the liquid pressure, gas pressure and capillary pressure of the pore body; and is the surface tension coefficient of liquid water in the pore and the inscribed sphere radius of the pore; Indicates that the above 10-2< slPN The equation is linearly extended in the range <1 - 10-6.

[0061] Furthermore, the interface coupling conditions between the hot air channel region and the porous medium region, the interface coupling conditions including the mass conservation interface coupling conditions and the momentum conservation interface coupling conditions, are used to couple and solve the control equations in the above two regions.

[0062] It is understandable that if Figure 2 As shown, the interface refers to the area where the hot air channel and the porous medium area meet.

[0063] Specifically, for the mass conservation interface coupling condition, the flow at the interface is continuous and the expression is:

[0064] in, The interface and the pore i The location of the connection; is the length of a finite volume method computational grid; is the normal vector of the interface pointing toward the free stream.

[0065] Specifically, for the momentum conservation interface coupling condition, the pressure in the two regions is continuous in the normal direction, and the expression is:

[0066] In the tangential direction, the Beavers-Joseph interface slip condition is used:

[0067] in, is the slip constant parameter, and It is a hole i Tangent vector and pore throat at interface ij The direction of pointing; The expression is pore throat ij The gas flow velocity in .

[0068] Step 4, the physical parameters of the porous interface to be tested, the boundary conditions and initial conditions of the hot air channel area and the coolant inlet, and the time step and total time of the transient calculation are input into the fully coupled model based on the porous interface phase change sweating. After the transient iterative solution, the predicted porous interface phase change sweating multi-physical field is obtained.

[0069] Specifically, the multi-physics field for predicting the phase change of porous interface includes predicting the temperature at the bottom of the hot air channel (at the wall of the porous interface near the leading edge of the aircraft in the hot air channel area) T , coolant inlet predicted mass flux ρcUc , predicted mass flux at the hot air channel inlet ρhUh , is the gas at the bottom wall of the hot air channel x Component of directional velocity , is the mainstream density of the hot air channel air , hot air channel and porous media area junction x Direction speed y Directional gradient distribution Dynamic viscosity distribution of mixed gas at the interface between hot air channel and porous medium area wait.

[0070] in, x Direction and y Direction Figure 2 In x Direction and y direction.

[0071] Step 5, based on the porous interface phase change sweating multi-physics field, obtain the cooling efficiency of the porous interface phase change sweating blowing area and the blowing trailing edge area, which is used to identify the high and low temperature extremes at the wall of the porous interface close to the leading edge end of the aircraft in the hot air channel area.

[0072] Furthermore, the cooling efficiency of the porous interface phase change sweat blowing area and the blowing trailing edge area is expressed as:

[0073] in, Indicates cooling efficiency; T∞ , T and Tc They are respectively the predicted hot air inflow temperature, the predicted temperature at the bottom of the hot air channel (at the wall of the porous interface close to the leading edge end of the aircraft in the hot air channel area) and the predicted coolant inlet temperature.

[0074] It is understandable that the predicted hot air inflow temperature T∞ The predicted coolant inlet temperature is obtained from the hot air channel inlet temperature in the boundary conditions of the hot air channel region in step 4. Tc Obtained from the coolant inlet temperature in the boundary conditions of the porous medium region in step 4.

[0075] Step 6, based on the porous interface phase change sweating multi-physics field, obtain the porous interface phase change sweating transient blowing ratio and total coolant consumption.

[0076] Specifically, the porous interface phase change sweating transient blowing ratio BR The expression is:

[0077] in, ρcUc represents the predicted coolant inlet mass flux; ρhUh represents the predicted mass flux at the hot air channel inlet; Indicates the coolant inlet location; Indicates the location of the hot air channel inlet.

[0078] Specifically, the total consumption of the porous interface phase change sweat coolant The expression is:

[0079] in, Ttotal is the total cooling time.

[0080] Step 7, based on the porous interface phase change sweating multi-physics field, obtain the porous interface phase change sweating friction reduction effect, which is used to determine the degree of reduction of interface shear stress caused by blowing.

[0081] It can be understood that the blowing is at the interface between the porous medium area and the hot air channel area. During the process of the gas inside the porous medium flowing to the hot air channel, the gas at the interface has y The flow will cause the connection between the wall and the hole to x Direction speed.

[0082] The gas at the bottom wall of the hot air channel obtained based on the solver x The component of the velocity in the direction of the hot air channel and the porous medium area is obtained. x Direction speed y The distribution of directional gradient and dynamic viscosity of mixed gas at the interface of hot air channel and porous medium area can be used to obtain the magnitude of interfacial shear stress and the dynamic viscosity of the mixture, thereby obtaining the effect of reducing friction of sweating porous interface, which is used to judge the degree of reduction of interfacial shear stress brought by blowing.

[0083] Specifically, the expression of the surface friction coefficient of porous interface phase change sweating is:

[0084] in, is the dynamic viscosity distribution of the mixed gas at the junction of the hot air channel area and the porous medium area, The gas at the bottom wall of the hot air channel x The component of the directional velocity, is the mainstream density of the hot air channel air; represents the coefficient of surface friction; Indicates the hot air channel area y Direction coordinates; Indicates the bottom wall position of the hot air channel; Indicates the mainstream position of air in the hot air channel area.

[0085] It can be understood that the smaller the surface friction coefficient of the porous interface phase change sweating is, the better the effect of reducing the friction resistance of the porous interface phase change sweating is.

[0086] In order to illustrate the effectiveness of the method proposed in the present invention, the above technical solution of the present invention is described in detail below through a specific embodiment, and the specific implementation steps are as follows: The first step, such as Figure 1 As shown, a fully coupled model of high enthalpy porous interface phase change sweating is constructed.

[0087] In the second step, the specific method for determining the parameters of the physical model of high enthalpy porous interface phase change sweating is to establish the params.input input file and input the physical control parameters of the hot air channel and the porous medium area. For the hot air channel, it mainly includes a channel length of 20 mm, a height of 4 mm, a width of 0.4 mm, and a number of grid nodes of 138×28; for the porous medium area, it mainly includes a porous medium length of 10 mm, a height of 10 mm, a number of pores in the porous medium along the height direction of 20, a number of pores along the length direction of 20, a pore shape of a cube, a pore throat cross-section shape of a square, a pore body inscribed circle radius of 150 μm, and a pore throat cross-section inscribed circle radius of 40 μm. The specific physical model obtained is as follows Figure 2 shown.

[0088] The third step is to determine the boundary conditions and initial conditions of the thermal environment and coolant supply. The specific method is: based on the params.input input file in the second step, continue to input the boundary conditions and initial condition parameters of the hot air channel and the porous medium area. For the hot air channel, it mainly includes the simulation base pressure of 105 Pa, the hot air channel inlet and outlet pressure difference of 1000 Pa, the hot air channel inlet temperature of 1500 K, and the hot air channel inlet air mole fraction of 1; for the porous medium area, it mainly includes the coolant inlet liquid phase pressure difference of 400 Pa, the coolant inlet temperature of 300 K, the coolant inlet liquid content of 1, the coolant inlet water vapor component fugacity of 1.004×105 Pa, and the initial water level height of the porous medium area of ​​6.897×10-3 m.

[0089] The fourth step is to solve the transient multi-physics field of high enthalpy porous interface phase change sweating. The specific method is: based on the params.input input file in the third step, continue to input the initial simulation time step, the maximum simulation time step, and the total simulation time size. After obtaining the complete params.input input file, run the high enthalpy porous interface phase change sweating fully coupled solver to solve the simulation calculation results under the input conditions.

[0090] The fifth step is to obtain the cooling efficiency of the blowing area and the blowing trailing edge area of ​​the sweating porous interface.

[0091] The cooling efficiency is calculated as Figure 3 As shown, it can be found that the blowing area has a fluctuating cooling efficiency, and the cooling efficiency of the blowing trailing edge gradually decreases.

[0092] Step 6: Obtain the transient blowing ratio and total coolant consumption of the sweating porous interface. The transient blowing solution is Figure 4 As shown, it can be found that in the initial state, the blowing ratio fluctuates greatly due to the infiltration of liquid and the rise of water level; after that, when it stabilizes, the blowing ratio stabilizes at a lower position.

[0093] The seventh step is to obtain the analysis of the friction reduction effect of the sweating porous interface. The friction coefficient is solved as Figure 5 As shown, it can be found that wall blowing can effectively reduce surface friction.

[0094] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A multi-scale fully coupled transient prediction method for the phase change sweating cooling effect of porous interfaces, characterized in that: The specific steps are as follows: Step 1, determining the physical models of the hot air channel region and the porous medium region of the porous interface; Step 2, determining the boundary conditions and initial conditions of the hot air channel area and the porous medium area; Step 3, based on the physical models of the hot air channel region and the porous medium region in step 1, and the boundary conditions and initial conditions in step 2, a fully coupled model of porous interface phase change sweating is constructed; Step 4, inputting the physical model of the porous interface to be measured, the boundary conditions and initial conditions of the hot air channel area and the coolant inlet, and the time step and total time length of the transient calculation into the fully coupled model based on the porous interface phase change sweating to obtain the predicted porous interface phase change sweating multi-physical field; Step 5, based on the porous interface phase change sweating multi-physics field, obtain the cooling efficiency of the porous interface phase change sweating blowing area and the blowing trailing edge area; Step 6, based on the porous interface phase change sweating multi-physics field, obtain the porous interface phase change sweating transient blowing ratio and the total coolant consumption; Step 7, based on the porous interface phase change sweating multi-physics field, obtain the porous interface phase change sweating friction reduction effect.

2. The multi-scale fully coupled transient prediction method according to claim 1, characterized in that: The physical parameters of the hot air channel area include the length, height, width and number of grid nodes in each section of the hot air channel; the physical parameters of the porous medium area include the number of pores, pore shape, pore throat cross-sectional shape, the size of the pore body inscribed sphere radius and the size of the pore throat cross-sectional inscribed circle radius.

3. The multi-scale fully coupled transient prediction method according to claim 1, characterized in that: The boundary conditions of the hot air channel area include the simulation reference pressure, the pressure difference between the hot air channel inlet and outlet, the hot air channel inlet temperature and the hot air channel inlet air concentration; For the porous medium region, the boundary conditions are the boundary conditions of coolant supply, which include the coolant inlet liquid phase pressure and coolant inlet temperature, coolant inlet liquid content and coolant inlet component fugacity; The initial conditions include the initial temperature, initial pressure, initial velocity and initial component distribution in the hot air channel area; the initial water level, initial temperature, initial pressure and initial component distribution in the porous medium area.

4. The multi-scale fully coupled transient prediction method according to claim 1, characterized in that: The specific steps for constructing the fully coupled model of porous interface phase change sweating in step 3 are: Establish the governing equations of the hot air channel region under the finite volume method and the governing equations of the porous medium region under the fully coupled model of porous interface phase change sweating, as well as the constitutive relations of the fully coupled model of two-phase flow in porous media and porous interface phase change sweating; Based on the interface coupling conditions of the hot air channel region and the porous medium region, and the boundary conditions of the channel hot air inlet and outlet and the coolant inlet; the control equations, constitutive relations, the boundary conditions and initial conditions of the hot air channel region and the coolant inlet are assembled to obtain a large matrix equation; the large matrix equation is iteratively solved to obtain a multi-scale fully coupled transient solution code; The multi-scale fully coupled transient solution code is compiled to obtain a porous interface phase change sweating fully coupled model of porous interface phase change sweating cooling effect.

5. The multi-scale fully coupled transient prediction method according to claim 1, characterized in that: The obtained predicted porous interface phase change sweating multi-physics fields include the predicted hot air channel bottom temperature, the coolant inlet predicted mass flux, the hot air channel inlet predicted mass flux, the gradient distribution at the interface between the hot air channel and the porous medium area, and the mixed gas dynamic viscosity distribution at the interface between the hot air channel and the porous medium area.

6. The multi-scale fully coupled transient prediction method according to claim 5, characterized in that: The expression of the cooling efficiency of the porous interface phase change sweat blowing area and the blowing trailing edge area in step 5 is: in, Indicates cooling efficiency; T∞ , T and Tc They are respectively the predicted hot air inlet temperature, the predicted hot air channel bottom temperature and the predicted coolant inlet temperature.

7. The multi-scale fully coupled transient prediction method according to claim 5, characterized in that: The transient blowing ratio of porous interface phase change sweating in step 6 BR The expression is: in, ρcUc represents the predicted coolant inlet mass flux; ρhUh represents the predicted mass flux at the hot air channel inlet; Indicates the coolant inlet location; Indicates the location of the hot air channel inlet.

8. The multi-scale fully coupled transient prediction method according to claim 5, characterized in that: Total consumption of coolant by phase change of porous interface The expression is: in, Ttotal is the total cooling time; ρcUc represents the predicted coolant inlet mass flux; ρhUh represents the predicted mass flux at the hot air channel inlet; Indicates the coolant inlet location.

9. The multi-scale fully coupled transient prediction method according to claim 5, characterized in that: The effect of reducing friction due to sweating at porous interface phase change in step 7 Cf The expression is: in, is the dynamic viscosity distribution of the mixed gas at the interface between the hot air channel and the porous medium area, The gas at the bottom wall of the hot air channel x The component of the directional velocity, is the mainstream density of the hot air channel air; represents the coefficient of surface friction; Indicates the hot air channel area y Direction coordinates; Indicates the bottom wall position of the hot air channel; Indicates the mainstream position of air in the hot air channel area.

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