A method, device, equipment, medium and product for identifying surface heat flow of carbonized ablative material

Abstract

This application discloses a method, apparatus, device, medium, and product for identifying the surface heat flux of carbonized ablation materials, relating to the field of carbonized ablation materials. The method includes: acquiring the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period; calculating the thickness time-domain history of the carbonized ablation material under test when pyrolysis has not occurred based on the temperature time-domain history and a thickness identification model; and calculating the surface heat flux of the carbonized ablation material under test based on the thickness time-domain history of the carbonized ablation material under test when pyrolysis has not occurred and the heat flux identification model to obtain the surface heat flux of the carbonized ablation material under test. This application can improve the accuracy of identifying the surface heat flux of ablation materials.

Description

Technical Field

[0001] This application relates to the field of carbonized ablation materials, and in particular to a method, apparatus, equipment, medium, and product for identifying surface heat flow of carbonized ablation materials. Background Technology

[0002] Thermal load identification is a key issue in the design and maintenance of spacecraft thermal protection structures. Due to the harsh aerodynamic and thermal environment faced by spacecraft during atmospheric flight, it is practically impossible to place sensors on the surface of the thermal protection structure to directly identify thermal loads. Currently, the industry standard for surface heat flow identification of thermal protection structures involves placing sensors inside the structure to collect temperature information, inverting the sensitivity matrix between surface heat flow and internal temperature, and then deducing the surface heat flow.

[0003] Ablation of materials involves complex physicochemical changes during the ablation process. The nonlinearity between surface load and bottom response is high. When solving for the sensitivity matrix, a clear sensitivity matrix is ​​usually not obtained. Therefore, when using such a low-clarity sensitivity matrix for calculation on ablation materials, the accuracy of identifying the surface heat flow of the ablation material is also very low. Summary of the Invention

[0004] The purpose of this application is to provide a method, apparatus, equipment, medium, and product for identifying heat flow on the surface of carbonized ablation materials, which can improve the accuracy of heat flow identification on the surface of ablation materials.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] In a first aspect, this application provides a method for identifying the surface heat flow of a carbonized ablation material, including:

[0007] Obtain the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period;

[0008] The thickness time-domain history of the tested carbonized ablation material before pyrolysis is calculated based on the temperature time-domain history and the thickness identification model. The material properties of the thickness identification model are the same as those of the tested carbonized ablation material before pyrolysis, and the initial size of the thickness identification model is the same as that of the tested carbonized ablation material before pyrolysis. The upper surface temperature of the thickness identification model is a fixed temperature, which is the temperature at which the tested carbonized ablation material begins to pyrolyze.

[0009] The surface heat flow of the carbonized ablation material under test is obtained by solving the thickness time-domain history and heat flow identification model when the carbonized ablation material under test has not undergone pyrolysis. The heat flow identification model has the same material properties as the carbonized ablation material under test in the three stages of no pyrolysis, pyrolysis and pyrolysis completion.

[0010] Secondly, this application provides a heat flow identification device for the surface of carbonized ablation materials, comprising:

[0011] The acquisition module is used to acquire the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period.

[0012] The thickness calculation module is used to calculate the thickness time-domain history of the tested carbonized ablation material before pyrolysis based on the temperature time-domain history and the thickness identification model; wherein, the material properties of the thickness identification model are the same as those of the tested carbonized ablation material before pyrolysis, and the initial size of the thickness identification model is the same as that of the tested carbonized ablation material before pyrolysis; the upper surface temperature of the thickness identification model is a fixed temperature, which is the temperature at which the tested carbonized ablation material begins to pyrolyze;

[0013] The heat flux calculation module is used to solve for the surface heat flux of the carbonized ablation material under test based on the thickness time-domain history and heat flux identification model when the carbonized ablation material under test has not undergone pyrolysis, so as to obtain the surface heat flux of the carbonized ablation material under test; wherein, the material properties of the heat flux identification model are the same as the material properties of the carbonized ablation material under test in the three stages of no pyrolysis, pyrolysis and pyrolysis completion.

[0014] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method for identifying the surface heat flow of carbonized ablation materials.

[0015] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for identifying heat flow on the surface of carbonized ablation materials.

[0016] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method for identifying the surface heat flow of carbonized ablation materials.

[0017] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0018] This application provides a method, apparatus, equipment, medium, and product for identifying the surface heat flow of carbonized ablation materials. The method involves dividing the carbonized ablation material under test into linear and nonlinear parts and solving the inverse problem sequentially to obtain the surface heat flow. In the linear part, the temperature time-domain history of the bottom surface of the carbonized ablation material and the thickness identification model are used to solve for the linear thickness of the carbonized ablation material before pyrolysis, thus obtaining the thickness time-domain history of the carbonized ablation material before pyrolysis. In the nonlinear part, the heat flow identification model and the thickness time-domain history of the carbonized ablation material before pyrolysis are used to solve for the surface heat flow. When solving for the surface heat flow, since the linear part is not considered, the distance between the upper and lower surfaces of the heat flow identification model is reduced, the heat transfer path is shortened, and the response between the surface load and the lower surface is more sensitive, allowing for a more accurate solution for the surface heat flow, thereby obtaining a more precise heat flow identification result. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an application environment diagram of a method for identifying surface heat flow of carbonized ablation materials according to an embodiment of this application;

[0021] Figure 2 A schematic flowchart illustrating a method for identifying surface heat flux of a carbonized ablation material according to an embodiment of this application;

[0022] Figure 3 for Figure 2 A detailed flowchart illustrating the steps for solving the time-domain history of the thickness of the carbonized ablation material under test when pyrolysis has not occurred.

[0023] Figure 4 This is a schematic diagram of the time-domain history thickness solution result of a thickness identification model provided in an embodiment of this application;

[0024] Figure 5 This is a schematic diagram of the surface heat flow identification results of a carbonized ablation material according to an embodiment of this application;

[0025] Figure 6 A comparison diagram of surface heat flow identification results and conventional methods provided in an embodiment of this application;

[0026] Figure 7This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The surface heat flow identification method for carbonized ablation materials provided in this application embodiment can be applied to, for example... Figure 1 In the application environment shown, terminal 102 communicates with server 104 via a network. A data storage system can store the data that server 104 needs to process. The data storage system can be set up independently, integrated into server 104, or placed in the cloud or on other servers. Terminal 102 can send the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period to server 104. After receiving the temperature time-domain history, server 104, based on the temperature time-domain history and a thickness identification model, solves for the thickness time-domain history of the carbonized ablation material under test when pyrolysis has not occurred, obtaining the thickness time-domain history of the carbonized ablation material under test when pyrolysis has not occurred. Then, based on the thickness time-domain history of the carbonized ablation material under test when pyrolysis has not occurred and a heat flow identification model, server 104 solves for the surface heat flow of the carbonized ablation material under test, obtaining the surface heat flow of the carbonized ablation material under test. Server 104 can then feed back the obtained surface heat flow of the carbonized ablation material under test to terminal 102. In addition, in some embodiments, the heat flow identification method for the surface of carbonized ablation materials can also be implemented by the server 104 or the terminal 102 separately. For example, the terminal 102 can directly process the temperature time-domain history, or the server 104 can obtain the temperature time-domain history from the data storage system and process it.

[0030] The terminal 102 can be, but is not limited to, various desktop computers, laptops, smartphones, and tablets. The server 104 can be implemented using a standalone server or a server cluster consisting of multiple servers, or it can be a cloud server.

[0031] In one exemplary embodiment, such as Figure 2As shown, a method for identifying surface heat flux of carbonized ablation materials is provided. This method is executed by a computer device, specifically a terminal or server, or both. In this embodiment, the method is applied to... Figure 1 Taking server 104 as an example, the explanation includes the following steps 201 to 203. Wherein:

[0032] Step 201: Obtain the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period.

[0033] To obtain a temperature time-domain history that can fully describe the response changes, a thermocouple sensor placed on the bottom surface of the carbonized ablation material under test collects the temperature time-domain history within a preset time period.

[0034] Step 202: Solve the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis based on the temperature time-domain history and thickness identification model.

[0035] The material properties of the thickness identification model are the same as those of the carbonized ablation material under test before pyrolysis, and the initial size of the thickness identification model is the same as that of the carbonized ablation material under test before pyrolysis. The upper surface temperature of the thickness identification model is a fixed temperature, which is the temperature at which the carbonized ablation material under test begins to pyrolyze.

[0036] The expression for the heat transfer control equation of the thickness identification model is:

[0037]

[0038] The expression for the boundary conditions of the thickness recognition model is:

[0039]

[0040] W(d,t)=W fix (3);

[0041] Among them, W fix For a fixed temperature, d represents the thickness time-domain history of the thickness identification model, ρ1, C1, and k1 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test before pyrolysis, respectively, W(x,t) represents the temperature field of the carbonized ablation material under test at time t with thickness x, W(0,t) represents the bottom surface temperature time-domain history of the thickness identification model, and W(d,t) represents the temperature time-domain history of the thickness identification model at x = d.

[0042] Step 203: Solve the surface heat flow of the carbonized ablation material under test based on the thickness time-domain history and heat flow identification model when the carbonized ablation material under test has not undergone pyrolysis, and obtain the surface heat flow of the carbonized ablation material under test.

[0043] The heat flow identification model has the same material properties as the tested carbonized ablation material in all three stages: no pyrolysis, pyrolysis, and pyrolysis completion.

[0044] The expressions for the heat transfer control equations and the corresponding temperature field conditions of the heat flow identification model are as follows:

[0045]

[0046]

[0047] The expression for the boundary conditions of the heat flux identification model is:

[0048]

[0049] Wherein, ρ2, C2, and k2 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test during pyrolysis, respectively; ρ3, C3, and k3 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test during the pyrolysis completion stage, respectively; and C... g h represents the specific heat of the gas produced during the pyrolysis of the carbonized ablation material to be tested. g The enthalpy is the value of the gas produced during the pyrolysis of the carbonized ablation material to be tested. W represents the gas mass flow rate generated during pyrolysis and at the completion stage of pyrolysis of the tested carbonized ablation material, respectively. char W represents the pyrolysis completion temperature of the carbonized ablation material to be tested. ablation denoted as ε, where ε is the ablation temperature of the carbonized material to be tested, Q is the surface heat flux, ε is the surface emissivity, σ is the Stefan-Boltzmann constant, W(L,t) is the time-domain history of the upper surface temperature of the carbonized material to be tested, i.e., the temperature of the heat flux identification model at x = L, L is the thickness time-domain history of the heat flux identification model, and W(0,t) is the temperature time-domain history of the heat flux identification model at x = 0.

[0050] This application improves the accuracy of heat flow identification results by constructing a thickness identification model and a heat flow identification model to solve the surface heat flow of the carbonized ablation material under test.

[0051] In an exemplary embodiment, step 202 includes steps 301-307:

[0052] Step 301: Set the initial thickness time-domain history of the thickness recognition model.

[0053] The boundary conditions of the thickness identification model can be set as follows: if the coordinates of the bottom surface of the thickness identification model are x = 0, then x = 0 is an adiabatic boundary condition; and x = d is a fixed temperature boundary condition.

[0054] Step 302: Calculate the initial bottom surface temperature time-domain history of the thickness identification model based on the initial thickness time-domain history. Specifically, this includes steps 31-37:

[0055] Step 31: Divide the preset time period into multiple time steps. Specifically, divide the preset time period into t... total The computation time is divided into M time steps, then the Δt for each time step is:

[0056]

[0057] Step 32: Divide the space corresponding to the initial thickness time-domain history into multiple small intervals and multiple spatial nodes; specifically, divide the spatial interval of the initial thickness time-domain history d(t) into N small intervals, resulting in N+1 spatial nodes, and the spatial step size Δx(t) of each small interval is:

[0058]

[0059] Step 33: Update the space at each time step and calculate the position of each spatial node; specifically, the position x of each spatial node. i (t)=i*Δx(t), where i=0, 1, 2,...,N.

[0060] Step 34: Update the time of each spatial node in the temperature field using the forward difference algorithm.

[0061] Specifically, the discrete-time derivative is obtained using the forward difference algorithm:

[0062]

[0063] Among them, W i n =W(i*Δx(t), n*Δt), n=0, 1, 2,...,M.

[0064] Step 35: Update the position of each spatial node in the temperature field using the central difference algorithm.

[0065] Specifically, the second-order spatial derivative is discretized using the central difference algorithm:

[0066]

[0067] Step 36: Based on the updated time and position of each spatial node, the heat transfer control equation of the thickness identification model, and the boundary conditions of the thickness identification model, obtain the temperature of all spatial nodes within the thickness identification model at all times.

[0068] Based on formulas (11) and (12), we update formula (1) to obtain:

[0069]

[0070] The spatial step size Δx(t) must be updated according to d(t) at each time step.

[0071] Update the known boundary conditions to a discrete format:

[0072] isothermal boundary equation: W N =W fix ;

[0073] Adiabatic boundary equation: W1 = W0;

[0074] Among them, W fix To maintain a constant temperature, W N W1 represents the temperature field of the thickness identification model at x = N*Δx(t), W2 represents the temperature field of the thickness identification model at x = 1*Δx(t), and W3 represents the temperature field of the thickness identification model at x = 0.

[0075] Initialize the temperature field and set W 0 =W initial W initial The initial temperature is given at time t=0. The boundary conditions are not covered by the temperature field initialization.

[0076] Iterative calculations are performed according to formula (13). When n=0, all the right-hand side of formula (13) is known, and the left-hand side is calculated. The left-hand side represents the temperature of the right-hand side after the time interval Δt. N calculations are performed at each time step, traversing all spatial nodes. There are a total of M time steps, and a total of M*N calculations are performed to obtain the temperature of all spatial nodes at all times.

[0077] Step 37: Obtain the initial bottom surface temperature time-domain history of the thickness recognition model based on the temperatures of all spatial nodes within the thickness recognition model at all times.

[0078] The temperature at x=0 on the bottom surface of the thickness recognition model is determined by using the temperatures of all spatial nodes at all times, and the boundary conditions of the thickness recognition model are updated.

[0079] Step 303: Construct a temperature objective function with the goal of minimizing the difference between the bottom surface temperature time-domain history and the temperature time-domain history.

[0080] Specifically, the temperature objective function S(d) of the thickness recognition model is set based on the least squares principle, and a regularization term is introduced to reduce the instability caused by measurement errors. The expression of the temperature objective function is as follows:

[0081]

[0082] Where Y(t) is the temperature time-domain history, W(0,t) is the bottom surface temperature time-domain history of the thickness identification model, T is the transpose of the matrix, and α is the regularization coefficient, which is a constant 0.1 in the thickness identification model.

[0083] Based on the excitation-response relationship between the thickness time-domain history and the bottom surface temperature time-domain history of the thickness identification model, a first sensitivity matrix J1 is constructed. The expression for the first sensitivity matrix J1 is:

[0084]

[0085] Step 304: Determine the linear thickness update formula based on the temperature objective function, the time-domain history of the bottom surface temperature, and the first sensitivity matrix.

[0086] Differentiating the temperature objective function S(d) with respect to d and setting it to 0, and substituting the Taylor expansion of the bottom surface temperature time-domain history W(0,t) with respect to d, we obtain the linear thickness update formula for the thickness time-domain history d of the thickness recognition model:

[0087]

[0088] Where I is the identity matrix, d j+1 Y(t) represents the time-domain history of the thickness recognition model after the (j+1)th update, and Y(t) represents the time-domain history of the temperature. j Let W(0, t) be the first sensitivity matrix at the j-th update. j This represents the time-domain history of the bottom surface temperature of the thickness identification model after the j-th update.

[0089] Step 305: Calculate the function value of the temperature objective function based on the initial bottom surface temperature time-domain history and the temperature time-domain history.

[0090] Substitute the initial bottom surface temperature time-domain history and the collected temperature time-domain history into formula (14) to calculate the function value of the temperature objective function, and determine whether the function value of the temperature objective function meets the stopping criterion.

[0091] The stopping criteria include a first preset condition and a first stopping condition. When the function value of the temperature objective function is calculated using the initial bottom surface temperature time-domain history, the stopping criterion used to judge the function value of this temperature objective function is the first stopping condition. During the iterative update process, the function value of the temperature objective function is calculated, and the function value of the temperature objective function is judged. At this time, the stopping criterion used is the first preset condition.

[0092] If yes, proceed to step 306; otherwise, proceed to step 307.

[0093] Step 306: If the value of the temperature objective function is less than the preset value, then the initial thickness time-domain history is determined to be the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis.

[0094] Specifically, the value of the temperature objective function satisfies the stopping criterion, which is the first stopping condition. The first stopping condition is that the value of the temperature objective function is less than a preset value, and its expression is:

[0095] S(d) < 0.1 (17).

[0096] Step 307: If the value of the temperature objective function is greater than or equal to a preset value, then the initial thickness time-domain history is updated using the linear thickness update formula until the value of the temperature objective function satisfies a first preset condition; wherein, the first preset condition is that the difference between the value of the temperature objective function calculated in two adjacent update processes is less than a stop preset value.

[0097] If the value of the temperature objective function does not meet the stopping criterion, that is, if the value of the temperature objective function is greater than or equal to the preset value, then the initial thickness time-domain history is updated using the linear thickness update formula (16) until the value of the temperature objective function meets the first preset condition, and the updated thickness time-domain history is output. At this time, the first preset condition is the stopping criterion, and the updated thickness time-domain history is the thickness time-domain history of the carbonized ablation material to be tested when it has not undergone pyrolysis.

[0098] The expression for the first preset condition is:

[0099] |S(d j+1 )-S(d j )|≤1%(18);

[0100] Wherein S(d j+1 Let S(d) be the temperature objective function calculated during the (j+1)th update process. j ) is the temperature objective function calculated during the j-th update process.

[0101] In an exemplary embodiment, the process of identifying surface heat flow using the bottom surface temperature of the carbonized ablation material to be measured is as follows: Figure 3 As shown, the temperature time-domain history of the bottom surface of the carbonized ablation material under test is obtained within a preset time period. A thickness identification model is established, and the initial value of the thickness time-domain history of the carbonized ablation material under test when no pyrolysis occurs is given. The temperature time-domain history of the bottom surface is calculated based on the initial values ​​of the temperature time-domain history and the thickness time-domain history, and the function value of the temperature objective function is calculated based on the initial values ​​of the temperature time-domain history and the thickness time-domain history. It is then determined whether the stopping criterion is met, which is the first stopping condition. If yes, the thickness time-domain history is output, and the output thickness time-domain history is the initial value of the thickness time-domain history. If no, the first sensitivity matrix is ​​calculated based on the initial value of the thickness time-domain history, and then the estimated value of the thickness time-domain history is calculated according to the linear thickness update formula. The boundary conditions of the thickness identification model are updated based on the estimated value of the thickness time-domain history, and the function value of the temperature objective function is recalculated. This process is repeated until the function value of the temperature objective function meets the first preset condition, which is the stopping criterion.

[0102] In an exemplary embodiment, step 203 includes steps 401-407:

[0103] Step 401: Initialize the surface heat flow and temperature field of the heat flow identification model of the carbonized ablation material to be tested, and obtain the initial values ​​of the heat flow and temperature field.

[0104] Step 402: Construct a heat flow objective function with the goal of minimizing the difference between the thickness time-domain history of the carbonized ablation material before pyrolysis and the thickness time-domain history of the linear part of the heat flow identification model.

[0105] Specifically, the heat flow objective function S(Q) of the heat flow identification model is set based on the least squares principle, and a regularization term is introduced to reduce the instability caused by measurement errors. The expression of the heat flow objective function is as follows:

[0106]

[0107] Where D is the thickness time-domain history of the linear part of the material in the heat flow identification model, and d is the thickness time-domain history output in step 202, which is the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis.

[0108] In the heat flow identification model, the regularization coefficient α is taken as a constant of 0.001.

[0109] The second sensitivity matrix J2 is constructed based on the excitation-response relationship of the surface heat flow and the thickness time-domain history of the linear portion of the material. The expression for the second sensitivity matrix J2 is as follows:

[0110]

[0111] Step 403: Determine the heat flow update formula based on the heat flow objective function, the thickness time-domain history of the linear part of the material in the heat flow identification model, and the second sensitivity matrix.

[0112] Differentiating the heat flux objective function S(Q) with respect to Q and setting it to 0, then substituting the Taylor expansion of D with respect to Q into the formula, we obtain the heat flux update formula:

[0113]

[0114] Where I is the identity matrix, Q k+1 Let Y(t) be the surface heat flux after the (k+1)th update, and let J2 be the temperature time-domain history. k Let D be the second sensitivity matrix at the k-th update. k This represents the time-domain history of the thickness of the linear component of the material in the heat flow identification model after the kth update.

[0115] Step 404: Calculate the time-domain thickness history of the linear part of the material in the heat flow identification model based on the initial heat flow value, the initial temperature field value, the heat transfer control equation of the heat flow identification model, the boundary conditions of the heat flow identification model, and the corresponding temperature field conditions.

[0116] The boundary conditions of the heat flux identification model can be set as follows: if the coordinates of the bottom surface of the heat flux identification model are x = 0, then x = 0 is the adiabatic boundary condition; if the coordinates of the top surface of the heat flux identification model are x = L, then heat flux is applied at x = L, which is the heat flux boundary condition.

[0117] Specifically, this includes steps S1-S7:

[0118] Step S1: Divide the preset time period into multiple time steps. Specifically, the preset time period is t. total The computation time is divided into M time steps, then each time step is:

[0119]

[0120] Step S2: Divide the space corresponding to the thickness of the heat flow identification model into multiple small intervals and multiple spatial nodes; specifically, divide the spatial interval of the thickness time-domain history L into N small intervals, resulting in N+1 spatial nodes, and the spatial step size of each small interval is:

[0121]

[0122] Step S3: Update the space at each time step and calculate the position of each spatial node; specifically, the position x of each spatial node. i=i*Δx, where i=0, 1, 2,...,N.

[0123] Step S4: Update the time of each spatial node in the temperature field using the forward difference algorithm.

[0124] Specifically, the discrete-time derivative is obtained using the forward difference algorithm:

[0125]

[0126] Among them, W i n =W(i*Δx,n*Δt), n=0, 1, 2,...,M.

[0127] Step S5: Update the position of each spatial node in the temperature field using a differential algorithm.

[0128] Specifically, the first spatial derivative is discretized using the backward difference algorithm:

[0129]

[0130] Discretize the second spatial derivative using the central difference algorithm:

[0131]

[0132] Step S6: Based on the updated time and position of each spatial node, the heat transfer control equation of the heat flow identification model, and the boundary conditions of the heat flow identification model, obtain the temperature of all spatial nodes within the heat flow identification model at all times.

[0133] Based on formulas (24), (25), and (26), we update formulas (4), (5), and (6) to obtain:

[0134]

[0135] To simulate the mass loss process of the carbonized ablation material under heat flow, the thickness time-domain history L of the heat flow identification model is a function of temperature:

[0136]

[0137] Among them, L n+1 To determine the thickness time-domain history of the heat flow identification model at time step n+1, H(·) is the Heaviside function, defined as:

[0138]

[0139] Accordingly, the spatial step size Δx must be updated according to L at each time step.

[0140] Update the known boundary conditions to a discrete format:

[0141] Heat flow boundary equation:

[0142] Adiabatic boundary equation: W1=W0(33);

[0143] in, W1 represents the temperature field of the heat flow identification model at time step n and x = N*Δx, W2 represents the temperature field of the heat flow identification model at x = 1*Δx, and W3 represents the temperature field of the heat flow identification model at x = 0.

[0144] Initialize the temperature field and set W 0 =W initial W initial Let t be the initial temperature at time t=0.

[0145] Iterative calculations are performed using formulas (27), (28), and (29). Based on the temperature of a spatial node at time step n, formula (27), (28), or (29) is chosen to calculate the temperature of that spatial node at time step n+1. Clearly, when n=0, the right side of the formula is known, and the left side can be calculated. The left side represents the temperature of the right side after the time interval Δt. N calculations are performed at each time step, traversing all spatial nodes. A total of M time steps are used, and M*N calculations are performed to obtain the temperatures of all spatial nodes at all times.

[0146] Step S7: Obtain the time-domain thickness history of the linear component material in the heat flux identification model based on the temperatures of all spatial nodes at all times within the model. The expression for the time-domain thickness history D of the linear component material in the heat flux identification model is:

[0147] D = arg x {W(x,t)=W fix}(34);

[0148] Where, arg x For all cases where W(x,t) = W fix A subset of x that holds true.

[0149] Step 405: Calculate the function value of the heat flow objective function based on the thickness time-domain history of the carbonized ablation material before pyrolysis and the thickness time-domain history of the linear part of the material in the heat flow identification model.

[0150] Step 406: If the function value of the heat flow objective function is less than the preset value, then the initial value of the heat flow is determined to be the surface heat flow of the carbonized ablation material to be tested.

[0151] Set the heat flow stop criteria, which include a second preset condition and a second stop preset value.

[0152] The heat flux objective function value is less than the preset value, i.e., the second stop preset value, expressed as:

[0153] S(Q) < 0.1(35);

[0154] If the function value of the heat flow objective function satisfies the heat flow stopping criterion, that is, the function value of the heat flow objective function is less than the preset value, then the initial value of the heat flow is determined to be the surface heat flow of the carbonized ablation material to be tested.

[0155] Step 407: If the function value of the heat flux objective function is greater than or equal to a preset value, then update the initial value of the heat flux according to the heat flux update formula until the function value of the heat flux objective function satisfies the second preset condition; wherein, the second preset condition is that the difference between the function values ​​of the heat flux objective function calculated in two adjacent update processes is less than a stop preset value.

[0156] If the function value of the heat flux objective function does not satisfy the heat flux stopping criterion, that is, the function value of the heat flux objective function is greater than or equal to the preset value, then the initial value of the heat flux is updated using the heat flux update formula (21), and the updated heat flux value becomes Q. k+1 The boundary conditions were changed accordingly, and the new boundary conditions became formula (34) until the function value of the heat flow objective function satisfies the second preset condition. Based on the new boundary conditions, the time-domain history D of the thickness of the linear part of the material in the new heat flow identification model was calculated. k+1 .

[0157]

[0158] The expression for the second preset condition is:

[0159] |S(Q k+1 )-S(Q k )|≤1% (38).

[0160] In an exemplary embodiment, a surface heat flow study was conducted using a carbonized ablation material as an example. Based on the temperature time-domain history of the bottom surface of the carbonized ablation material, the linear part was first solved to obtain the thickness time-domain history of the thickness identification model, such as... Figure 4 As shown. From Figure 4 As can be seen, the thickness recognition model achieves high accuracy in solving the time-domain thickness history. Using the time-domain thickness history results of this thickness recognition model as input, the nonlinear part is solved, such as... Figure 5 As shown. From Figure 5 The results show that the identified surface heat flow almost perfectly matches the actual heat flow, demonstrating the effectiveness of the surface heat flow identification method for carbonized ablation materials provided in this application. To further demonstrate the advantages of the surface heat flow identification method for carbonized ablation materials provided in this application, in... Figure 6 The paper presents a comparison of the surface heat flow identification results using the method for identifying the surface heat flow of carbonized ablation materials provided in this application and conventional methods.

[0161] Based on the same inventive concept, this application also provides a device for identifying the surface heat flow of carbonized ablation materials to implement the above-described method for identifying the surface heat flow of carbonized ablation materials. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the device for identifying the surface heat flow of carbonized ablation materials provided below can be found in the limitations of the method for identifying the surface heat flow of carbonized ablation materials described above, and will not be repeated here.

[0162] In one exemplary embodiment, a heat flow identification device for the surface of a carbonized ablation material is provided, comprising:

[0163] The acquisition module is used to acquire the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period.

[0164] The thickness calculation module is used to calculate the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis, based on the temperature time-domain history and the thickness identification model. The material properties of the thickness identification model are the same as those of the carbonized ablation material under test when it has not undergone pyrolysis, and the initial size of the thickness identification model is the same as that of the carbonized ablation material under test when it has not undergone pyrolysis. The upper surface temperature of the thickness identification model is a fixed temperature, which is the temperature at which the carbonized ablation material under test begins to pyrolyze.

[0165] The heat flux calculation module is used to solve for the surface heat flux of the carbonized ablation material under test based on the thickness time-domain history and heat flux identification model when the carbonized ablation material under test has not undergone pyrolysis, so as to obtain the surface heat flux of the carbonized ablation material under test; wherein, the material properties of the heat flux identification model are the same as the material properties of the carbonized ablation material under test in the three stages of no pyrolysis, pyrolysis and pyrolysis completion.

[0166] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 7As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs in the non-volatile storage media. The database stores the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for identifying the surface heat flow of carbonized ablation materials.

[0167] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0168] In one exemplary embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0169] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0170] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0171] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0172] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0173] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0174] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0175] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for identifying surface heat flux of carbonized ablation materials, characterized in that, The method for identifying surface heat flux of carbonized ablation materials includes: Obtain the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period; The thickness time-domain history of the tested carbonized ablation material before pyrolysis is calculated based on the temperature time-domain history and thickness identification model. Specifically, this includes: setting an initial thickness time-domain history for the thickness identification model; calculating the initial bottom surface temperature time-domain history of the thickness identification model based on the initial thickness time-domain history; constructing a temperature objective function with the goal of minimizing the difference between the bottom surface temperature time-domain history and the temperature time-domain history; determining a linear thickness update formula based on the temperature objective function, the bottom surface temperature time-domain history, and a first sensitivity matrix; calculating the function value of the temperature objective function based on the initial bottom surface temperature time-domain history and the temperature time-domain history; if the function value of the temperature objective function is less than a preset value, then the initial thickness time-domain history is determined to be the thickness time-domain history of the tested carbonized ablation material before pyrolysis. The initial thickness time-domain history is updated using the linear thickness update formula if the value of the temperature objective function is greater than or equal to a preset value, until the value of the temperature objective function satisfies a first preset condition. The first preset condition is that the difference between the values ​​of the temperature objective function calculated in two adjacent update processes is less than a stop preset value. The material properties of the thickness identification model are the same as those of the tested carbonized ablation material before pyrolysis, and the initial size of the thickness identification model is the same as that of the tested carbonized ablation material before pyrolysis. The upper surface temperature of the thickness identification model is a fixed temperature, which is the temperature at which the tested carbonized ablation material begins pyrolysis. The expression for the heat transfer control equation of the thickness identification model is: The expression for the boundary conditions of the thickness recognition model is: W(d,t)=W fix ; Among them, W fix For a fixed temperature, d is the thickness time-domain history of the thickness identification model, ρ1, C1 and k1 are the density, specific heat and thermal conductivity of the carbonized ablation material under test when it has not undergone pyrolysis, respectively, W(x,t) is the temperature field of the carbonized ablation material under test at time t with thickness x, W(0,t) is the bottom surface temperature time-domain history of the thickness identification model, and W(d,t) is the temperature time-domain history of the thickness identification model at x=d. The expressions for the heat transfer control equations and the corresponding temperature field conditions of the heat flow identification model are as follows: The expression for the boundary conditions of the heat flux identification model is: Wherein, ρ2, C2, and k2 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test during pyrolysis, respectively; ρ3, C3, and k3 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test during the pyrolysis completion stage, respectively; and C... g h represents the specific heat of the gas produced during the pyrolysis of the carbonized ablation material to be tested. g The enthalpy is the value of the gas produced during the pyrolysis of the carbonized ablation material to be tested. W represents the gas mass flow rate generated during pyrolysis and at the completion stage of pyrolysis of the tested carbonized ablation material, respectively. char W represents the pyrolysis completion temperature of the carbonized ablation material to be tested. ablation denoted as ε, where ε is the ablation temperature of the carbonized material to be tested, Q is the surface heat flux, ε is the surface emissivity, σ is the Stefan-Boltzmann constant, W(L,t) is the time-domain history of the upper surface temperature of the carbonized material to be tested, L is the thickness time-domain history of the heat flux identification model, and W(0,t) is the temperature time-domain history of the heat flux identification model at x=0. The surface heat flux of the carbonized ablation material under test is obtained by solving the surface heat flux of the carbonized ablation material under test based on the thickness time-domain history of the carbonized ablation material before pyrolysis and the heat flux identification model. Specifically, this includes: initializing the surface heat flux of the carbonized ablation material under test and the temperature field of the heat flux identification model to obtain initial values ​​for heat flux and temperature field; constructing a heat flux objective function with the goal of minimizing the difference between the thickness time-domain history of the carbonized ablation material under test before pyrolysis and the thickness time-domain history of the linear part of the material in the heat flux identification model; determining the heat flux update formula based on the heat flux objective function, the thickness time-domain history of the linear part of the material in the heat flux identification model, and the second sensitivity matrix; and determining the heat flux update formula based on the initial values ​​for heat flux, the initial values ​​for temperature field, the heat transfer control equation of the heat flux identification model, the boundary conditions of the heat flux identification model, and the corresponding temperature field conditions. The thickness time-domain history of the linear component material in the heat flow identification model is calculated; the function value of the heat flow objective function is calculated based on the thickness time-domain history of the carbonized ablation material under test before pyrolysis and the thickness time-domain history of the linear component material in the heat flow identification model; if the function value of the heat flow objective function is less than a preset value, the initial heat flow value is determined to be the surface heat flow of the carbonized ablation material under test; if the function value of the heat flow objective function is greater than or equal to the preset value, the initial heat flow value is updated according to the heat flow update formula until the function value of the heat flow objective function satisfies a second preset condition; wherein, the second preset condition is that the difference between the function values ​​of the heat flow objective function calculated in two adjacent update processes is less than a stop preset value; the material properties of the heat flow identification model in the three stages of no pyrolysis, pyrolysis, and pyrolysis completion are the same as the material properties of the carbonized ablation material under test.

2. The method for identifying surface heat flow of carbonized ablation materials according to claim 1, characterized in that, The initial bottom surface temperature time-domain history of the thickness identification model is calculated based on the initial thickness time-domain history, including: The preset time period is divided into multiple time steps; The space corresponding to the initial thickness time-domain history is divided into multiple small intervals and multiple spatial nodes; The space is updated at each time step, and the position of each spatial node is calculated; The forward difference algorithm is used to update the time of each spatial node in the temperature field; The position of each spatial node in the temperature field is updated using the central difference algorithm; Based on the updated time and position of each spatial node, the heat transfer control equation of the thickness identification model, and the boundary conditions of the thickness identification model, the temperature of all spatial nodes in the thickness identification model at all times is obtained. The initial bottom surface temperature time-domain history of the thickness recognition model is obtained based on the temperatures of all spatial nodes within the model at all times.

3. The method for identifying surface heat flow of carbonized ablation materials according to claim 1, characterized in that, The expression for the temperature objective function is: Where S(d) is the temperature objective function, d is the thickness time-domain history of the thickness identification model, Y(y) is the temperature time-domain history, α is the regularization coefficient, W(0,t) is the bottom surface temperature time-domain history of the thickness identification model, and T is the transpose of the matrix. The expression for the heat flux objective function is: Where S(Q) is the heat flow objective function, and D is the thickness time-domain history of the linear part of the material in the heat flow identification model.

4. A device for identifying the surface heat flow of carbonized ablation materials, characterized in that, The surface heat flow identification device for carbonized ablation materials includes: The acquisition module is used to acquire the temperature time-domain history of the bottom surface of the carbonized ablation material under test within a preset time period. The thickness calculation module is used to calculate the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis, based on the temperature time-domain history and the thickness identification model. Specifically, the thickness calculation module includes: a first initialization module for setting the initial thickness time-domain history of the thickness identification model; a first calculation module for calculating the initial bottom surface temperature time-domain history of the thickness identification model based on the initial thickness time-domain history; a construction module for constructing a temperature objective function with the goal of minimizing the difference between the bottom surface temperature time-domain history and the temperature time-domain history; an update formula determination module for determining a linear thickness update formula based on the temperature objective function, the bottom surface temperature time-domain history, and the first sensitivity matrix; a second calculation module for calculating the function value of the temperature objective function based on the initial bottom surface temperature time-domain history and the temperature time-domain history; and a thickness time-domain history determination module for determining the thickness if the function value of the temperature objective function is less than... If a preset value is set, the initial thickness time-domain history is determined to be the thickness time-domain history of the carbonized ablation material under test before pyrolysis. The thickness time-domain history update module is used to update the initial thickness time-domain history using the linear thickness update formula if the function value of the temperature objective function is greater than or equal to the preset value, until the function value of the temperature objective function satisfies a first preset condition. The first preset condition is that the difference between the function values ​​of the temperature objective function calculated in two adjacent update processes is less than a stop preset value. The material properties of the thickness identification model are the same as those of the carbonized ablation material under test before pyrolysis, and the initial size of the thickness identification model is the same as that of the carbonized ablation material under test before pyrolysis. The upper surface temperature of the thickness identification model is a fixed temperature, which is the temperature at which the carbonized ablation material under test begins to pyrolyze. The expression for the heat transfer control equation of the thickness identification model is: The expression for the boundary conditions of the thickness recognition model is: W(d,t)=W fix ; Among them, W fix For a fixed temperature, d is the thickness time-domain history of the thickness identification model, ρ1, C1 and k1 are the density, specific heat and thermal conductivity of the carbonized ablation material under test when it has not undergone pyrolysis, respectively, W(x,t) is the temperature field of the carbonized ablation material under test at time t with thickness x, W(0,t) is the bottom surface temperature time-domain history of the thickness identification model, and W(d,t) is the temperature time-domain history of the thickness identification model at x=d. The expressions for the heat transfer control equations and the corresponding temperature field conditions of the heat flow identification model are as follows: The expression for the boundary conditions of the heat flux identification model is: Wherein, ρ2, C2, and k2 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test during pyrolysis, respectively; ρ3, C3, and k3 represent the density, specific heat, and thermal conductivity of the carbonized ablation material under test during the pyrolysis completion stage, respectively; and C... g h represents the specific heat of the gas produced during the pyrolysis of the carbonized ablation material to be tested. g The enthalpy is the value of the gas produced during the pyrolysis of the carbonized ablation material to be tested. W represents the gas mass flow rate generated during pyrolysis and at the completion stage of pyrolysis of the tested carbonized ablation material, respectively. char W represents the pyrolysis completion temperature of the carbonized ablation material to be tested. ablation denoted as ε, where ε is the ablation temperature of the carbonized material to be tested, Q is the surface heat flux, ε is the surface emissivity, σ is the Stefan-Boltzmann constant, W(L,t) is the time-domain history of the upper surface temperature of the carbonized material to be tested, L is the thickness time-domain history of the heat flux identification model, and W(0,t) is the temperature time-domain history of the heat flux identification model at x=0. The heat flux calculation module is used to solve for the surface heat flux of the carbonized ablation material under test based on the thickness time-domain history and heat flux identification model when the carbonized ablation material under test has not undergone pyrolysis, thereby obtaining the surface heat flux of the carbonized ablation material under test; the heat flux calculation module specifically includes: The second initialization module is used to initialize the surface heat flow and temperature field of the heat flow identification model of the carbonized ablation material to be tested, and to obtain the initial values ​​of the heat flow and the initial values ​​of the temperature field. The heat flux objective function construction module is used to construct a heat flux objective function with the objective of minimizing the difference between the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis and the thickness time-domain history of the linear part of the material in the heat flux identification model. The heat flux update formula determination module is used to determine the heat flux update formula based on the heat flux objective function, the thickness time-domain history of the linear part of the material in the heat flux identification model, and the second sensitivity matrix. The thickness time-domain history calculation module is used to calculate the thickness time-domain history of the linear part of the material in the heat flow identification model based on the initial value of heat flow, the initial value of temperature field, the heat transfer control equation of the heat flow identification model, the boundary conditions of the heat flow identification model, and the corresponding temperature field conditions. The heat flux objective function calculation module is used to calculate the function value of the heat flux objective function based on the thickness time-domain history of the carbonized ablation material under test when it has not undergone pyrolysis and the thickness time-domain history of the linear part of the material in the heat flux identification model. A surface heat flux determination module is used to determine the initial value of the heat flux as the surface heat flux of the carbonized ablation material to be tested if the function value of the heat flux objective function is less than a preset value. The surface heat flux update module is used to update the initial value of the heat flux according to the heat flux update formula if the function value of the heat flux objective function is greater than or equal to a preset value, until the function value of the heat flux objective function satisfies a second preset condition; wherein, the second preset condition is that the difference between the function values ​​of the heat flux objective function calculated in two adjacent update processes is less than a stop preset value; the material properties of the heat flux identification model are the same as those of the carbonized ablation material to be tested in the three stages of no pyrolysis, pyrolysis, and pyrolysis completion.

5. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the method for identifying the surface heat flow of carbonized ablation materials according to any one of claims 1-3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the method for identifying the surface heat flow of carbonized ablation materials as described in any one of claims 1-3.

7. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the method for identifying the surface heat flow of carbonized ablation materials as described in any one of claims 1-3.

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