Carbonized ablative material surface heat flow identification method, device, equipment, medium and product

Abstract

The invention discloses a carbonized ablative material surface heat flow identification method, device and equipment, a medium and a product, and relates to the field of carbonized ablative materials.The method comprises the steps that the temperature time domain history of the bottom face of a carbonized ablative material to be measured within a preset time period is obtained; according to the temperature time domain process and a thickness identification model, solving a thickness time domain process when the carbonized ablative material to be measured is not pyrolyzed; and solving the surface heat flow of the to-be-measured carbonized ablative material according to the thickness time domain history when the to-be-measured carbonized ablative material is not pyrolyzed and a heat flow identification model to obtain the surface heat flow of the to-be-measured carbonized ablative material. The method can improve the recognition precision of the heat flow on the surface of the ablative material.

Description

Technical Field

[0001] The present application relates to the field of carbonized ablative materials, and in particular to a method, device, equipment, medium and product for identifying surface heat flow of carbonized ablative materials. Background Art

[0002] Thermal load identification is a key issue that needs to be paid attention to in the design and maintenance of spacecraft thermal protection structures. Due to the harsh aerodynamic thermal environment faced by spacecraft when flying in the atmosphere, it is basically impossible to place sensors on the surface of the thermal protection structure to directly identify the thermal load. At present, when the industry is identifying the surface heat flux of the thermal protection structure, sensors are placed inside the thermal protection structure to collect temperature information, and the sensitivity matrix between the surface heat flux and the internal temperature is inverted to infer the surface heat flux.

[0003] The ablation material involves complex physical and chemical changes during the ablation process. The nonlinearity between the surface load and the bottom surface response is high. When solving the sensitivity matrix, a clear sensitivity matrix cannot usually be obtained. Therefore, when using this low-definition sensitivity matrix for calculation on the ablation material, the recognition accuracy of the heat flow on the surface of the ablation material is also very low. Summary of the invention

[0004] The purpose of the present application is to provide a method, device, equipment, medium and product for identifying the surface heat flow of a carbonized ablative material, which can improve the identification accuracy of the surface heat flow of the ablative material.

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

[0006] In a first aspect, the present application provides a method for identifying heat flow on the surface of a carbonized ablative material, comprising:

[0007] Obtaining the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period;

[0008] Solving the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed according to the temperature time domain history and the thickness identification model; wherein the material properties of the thickness identification model are the same as the material properties of the carbonized ablative material to be tested when it has not been pyrolyzed, and the initial size of the thickness identification model is the same as the size of the carbonized ablative material to be tested when it has not been pyrolyzed, and the upper surface temperature of the thickness identification model is a fixed temperature, and the fixed temperature is the temperature at which the carbonized ablative material to be tested begins to pyrolyze;

[0009] The surface heat flux of the carbonized ablative material to be tested is solved according to the thickness time domain history when the carbonized ablative material to be tested has not been pyrolyzed and the heat flow identification model, so as to obtain the surface heat flux of the carbonized ablative material to be tested; wherein the material properties of the heat flow identification model in the three stages of no pyrolysis, pyrolysis and completion of pyrolysis are the same as the material properties of the carbonized ablative material to be tested.

[0010] In a second aspect, the present application provides a device for identifying heat flow on the surface of a carbonized ablative material, comprising:

[0011] An acquisition module, used to acquire the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period;

[0012] A thickness solving module, used for solving the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed according to the temperature time domain history and the thickness identification model; wherein the material properties of the thickness identification model are the same as the material properties of the carbonized ablative material to be tested when it has not been pyrolyzed, and the initial size of the thickness identification model is the same as the size of the carbonized ablative material to be tested when it has not been pyrolyzed, and the upper surface temperature of the thickness identification model is a fixed temperature, and the fixed temperature is the temperature at which the carbonized ablative material to be tested begins to pyrolyze;

[0013] The heat flow solving module is used to solve the surface heat flow of the carbonized ablative material to be tested according to the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed and the heat flow identification model, so as to obtain the surface heat flow of the carbonized ablative material to be tested; wherein 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 ablative material to be tested.

[0014] In a third aspect, the present 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-mentioned method for identifying heat flow on the surface of carbonized ablative material.

[0015] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned method for identifying the surface heat flow of carbonization-type ablative materials.

[0016] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned method for identifying the surface heat flow of carbonization-type ablative materials.

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

[0018] The present application provides a method, device, equipment, medium and product for identifying the surface heat flow of a carbonized ablative material. The method divides the carbonized ablative material to be tested into two parts, linear and nonlinear, and solves the inverse problem in sequence to obtain the surface heat flow of the carbonized ablative material to be tested. In the linear part, the linear thickness of the carbonized ablative material to be tested before pyrolysis is solved by using the temperature time domain history of the bottom surface of the carbonized ablative material to be tested and a thickness identification model, so as to obtain the thickness time domain history of the carbonized ablative material to be tested before pyrolysis. In the nonlinear part, the surface heat flow of the carbonized ablative material to be tested is solved by using the heat flow identification model and the thickness time domain history of the carbonized ablative material to be tested before pyrolysis. When solving the surface heat flow, since the linear part is not considered, the distance between the upper surface and the bottom surface of the heat flow identification model is reduced, and the heat transfer path of the heat is shortened, so that the response between the surface load and the bottom surface is more sensitive, and the surface heat flow can be solved more accurately, thereby obtaining a heat flow identification result with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is an application environment diagram of a method for identifying heat flow on the surface of a carbonized ablative material in one embodiment of the present application;

[0021] Figure 2 A schematic diagram of a process for identifying heat flow on the surface of a carbonized ablative material provided in one embodiment of the present application;

[0022] Figure 3 for Figure 2 A detailed flow chart of the steps for solving the thickness time domain history of the carbonized ablation material to be tested when no pyrolysis occurs;

[0023] Figure 4 A schematic diagram of a time domain history thickness solution result of a thickness identification model provided in one embodiment of the present application;

[0024] Figure 5 A schematic diagram of heat flow identification results of a carbonized ablative material surface provided in one embodiment of the present application;

[0025] Figure 6 A comparison chart of the surface heat flow identification results provided by an embodiment of the present application and the identification results by the traditional method;

[0026] Figure 7A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0029] The surface heat flow identification method of carbonization ablative material provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store the data that the server 104 needs to process. The data storage system can be set up separately, or it can be integrated on the server 104, or it can be placed on the cloud or other servers. The terminal 102 can send the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period to the server 104. After the server 104 receives the temperature time domain history, for the temperature time domain history, the server 104 solves the thickness time domain history of the carbonized ablation material to be tested when it is not pyrolyzed according to the temperature time domain history and the thickness recognition model, and obtains the thickness time domain history of the carbonized ablation material to be tested when it is not pyrolyzed, and solves the surface heat flow of the carbonized ablation material to be tested according to the thickness time domain history of the carbonized ablation material to be tested when it is not pyrolyzed and the heat flow recognition model, and obtains the surface heat flow of the carbonized ablation material to be tested. The server 104 can feedback the obtained surface heat flow of the carbonized ablation material to be tested to the terminal 102. In addition, in some embodiments, the surface heat flow identification method of carbonized ablative material can also be implemented independently by the server 104 or the terminal 102. 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 the temperature time domain history.

[0030] The terminal 102 may be, but is not limited to, various desktop computers, laptop computers, smart phones, and tablet computers. The server 104 may be implemented as an independent server or a server cluster consisting of multiple servers, or may be a cloud server.

[0031] In an exemplary embodiment, Figure 2As shown, a method for identifying the surface heat flow of a carbonized ablative material is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or can be executed by a terminal and a server together. In the embodiment of the present application, the method is applied to Figure 1 The server 104 in the example is used as an example to illustrate, including the following steps 201 to 203. Among them:

[0032] Step 201 : obtaining the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period.

[0033] In order to obtain the temperature time domain history that can fully describe the response change, the temperature time domain history within a preset time period is collected by a thermocouple sensor arranged on the bottom surface of the carbonization type ablation material to be tested.

[0034] Step 202 : solving the thickness time domain history of the carbonized ablation material to be tested when it is not pyrolyzed according to the temperature time domain history and the thickness identification model.

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

[0036] The heat transfer control equation of the thickness identification model is expressed as:

[0037]

[0038] The boundary condition expression of the thickness identification model is:

[0039]

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

[0041] Among them, W fix is 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 to be tested before pyrolysis respectively, W(x, t) is the temperature field of the carbonized ablation material to be tested with a thickness of x at time t, 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.

[0042] Step 203 , solving the surface heat flux of the carbonized ablation material to be tested according to the thickness time domain history of the carbonized ablation material to be tested when it is not pyrolyzed and the heat flux identification model, to obtain the surface heat flux of the carbonized ablation material to be tested.

[0043] 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 carbonization-type ablation material to be tested.

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

[0045]

[0046]

[0047] The boundary condition expression of the heat flow identification model is:

[0048]

[0049] Among them, ρ2, C2 and k2 are the density, specific heat and thermal conductivity of the carbonized ablation material to be tested during pyrolysis, ρ3, C3 and k3 are the density, specific heat and thermal conductivity of the carbonized ablation material to be tested at the stage of pyrolysis completion, C g is the specific heat of the gas generated by the pyrolysis of the carbonized ablation material to be tested, h g is the enthalpy value of the gas generated during the pyrolysis of the carbonized ablation material to be tested, are the gas mass flow rates generated by the carbonized ablation material during pyrolysis and at the completion of pyrolysis, W char is the pyrolysis completion temperature of the carbonized ablation material to be tested, W ablation 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 surface temperature of the carbonized material to be tested, that is, the temperature of the heat flow identification model at x=L, L is the thickness time domain history of the heat flow identification model, and W(0,t) is the temperature time domain history of the heat flow identification model at x=0.

[0050] The present application solves the surface heat flow of the carbonized ablation material to be tested by constructing a thickness identification model and a heat flow identification model, thereby improving the accuracy of the heat flow identification result.

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

[0052] Step 301, setting 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: assuming that the bottom coordinate of the thickness identification model is x=0, then x=0 is an adiabatic boundary condition; and x=d is a fixed temperature, i.e., a constant temperature boundary condition.

[0054] Step 302, calculating the initial bottom surface temperature time domain history of the thickness identification model according to the initial thickness time domain history. Specifically including steps 31 to 37:

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

[0056]

[0057] Step 32, divide the space corresponding to the initial thickness time domain history into multiple small intervals and multiple space nodes; specifically, divide the space interval of the initial thickness time domain history d(t) into N small intervals, then N+1 space nodes are obtained, and each small interval, that is, the space step length Δx(t) is:

[0058]

[0059] Step 33, updating the space in each time step and calculating 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, using a forward difference algorithm to update the time of each spatial node in the temperature field.

[0061] Specifically, the time derivatives are discretized 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, using the central difference algorithm to update the position of each spatial node in the temperature field.

[0065] Specifically, the central difference algorithm is used to discretize the second-order spatial derivative:

[0066]

[0067] Step 36, according to the updated time and updated 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,

[0068] According to formula (11) and formula (12), formula (1) is updated 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] Constant temperature boundary equation: W N =W fix ;

[0073] Adiabatic boundary equation: W1 = W0;

[0074] Among them, W fix is a fixed temperature, W N is the temperature field of the thickness identification model at x=N*Δx(t), W1 is the temperature field of the thickness identification model at x=1*Δx(t), and W0 is the temperature field of the thickness identification model at x=0.

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

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

[0077] Step 37, obtaining the time domain history of the initial bottom surface temperature of the thickness identification model according to the temperatures of all spatial nodes in the thickness identification model at all times.

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

[0079] Step 303, 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.

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

[0081]

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

[0083] The first sensitivity matrix J1 is constructed according to the excitation-response relationship between the thickness time domain history and the bottom surface temperature time domain history of the thickness recognition model. The expression of the first sensitivity matrix J1 is:

[0084]

[0085] Step 304: determine a linear thickness update formula according to the temperature target function, the bottom surface temperature time domain history and the first sensitivity matrix.

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

[0087]

[0088] Where I is the identity matrix, d j+1 is the thickness time domain history of the thickness recognition model after the j+1th update, Y(t) is the temperature time domain history, J1 j is the first sensitivity matrix at the jth update, W(0, t) j is the time domain history of the bottom surface temperature of the thickness identification model after the jth update.

[0089] Step 305 , calculating the function value of the temperature target function according to the initial bottom surface temperature time domain history and the temperature time domain history.

[0090] Substitute the set 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 target function is calculated using the time domain history of the initial bottom surface temperature, the stopping criteria used when judging the function value of the temperature target function is the first stopping condition; in the iterative update process, the function value of the temperature target function is calculated, and the function value of the temperature target function is judged, and the stopping criteria used at this time is the first preset condition.

[0092] If yes, execute step 306 ; if no, execute step 307 .

[0093] Step 306: If the function value of the temperature target function is less than a preset value, determine that the initial thickness time domain history is the thickness time domain history of the carbonized ablation material to be tested when no pyrolysis occurs.

[0094] Specifically, the function value of the temperature objective function satisfies the stopping criterion, the stopping criterion is the first stopping condition, and the first stopping condition is that the function 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 function value of the temperature objective function is greater than or equal to the preset value, the initial thickness time domain history is updated using the linear thickness update formula until the function value of the temperature objective function meets the first preset condition; wherein 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 the stop preset value.

[0097] If the function value of the temperature objective function does not meet the stopping criterion, that is, the function value of the temperature objective function is greater than or equal to the preset value, the linear thickness update formula (16) is used to update the initial thickness time domain history until the function 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 when the carbonized ablation material to be tested has not been pyrolyzed.

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

[0099] |S(d j+1 )-S(d j )|≤1%(18);

[0100] Among them, S(d j+1 ) is the temperature objective function calculated in the j+1th update process, S(d j ) is the temperature objective function calculated during the j-th update process.

[0101] In an exemplary embodiment, the process of using the bottom surface temperature of the carbonized ablation material to be tested to identify the surface heat flux is as follows: Figure 3 As shown, the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period is obtained, a thickness recognition model is established, and the initial value of the thickness time domain history of the carbonized ablation material to be tested when no pyrolysis occurs is given, the bottom surface temperature time domain history is calculated according to the initial values ​​of the temperature time domain history and the thickness time domain history, and the function value of the temperature target function is calculated according to the initial values ​​of the temperature time domain history and the thickness time domain history; it is judged whether the stopping criterion is met, and the stopping criterion is the first stopping condition at this time; if yes, the thickness time domain history is output, and the thickness time domain history output at this time is the initial value of the thickness time domain history; if not, the first sensitivity matrix is ​​calculated according to 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 recognition model are updated according to the estimated value of the thickness time domain history, and the function value of the temperature target function is recalculated, and the execution is repeated until the function value of the temperature target function meets the first preset condition, and the first preset condition is the stopping criterion at this time.

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

[0103] Step 401, initializing the surface heat flux of the carbonization-type ablation material to be tested and the temperature field of the heat flux identification model to obtain the initial value of the heat flux and the initial value of the temperature field.

[0104] Step 402 , constructing a heat flow objective function with the goal of minimizing the difference between the thickness time-domain history of the carbonized ablation material to be tested when it is not pyrolyzed and the thickness time-domain history of the linear part material in 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:

[0106]

[0107] Wherein, D is the thickness time-domain history of the linear part material in the heat flow identification model, and d is the thickness time-domain history outputted in step 202, that is, the thickness time-domain history of the carbonized ablation material to be tested when no pyrolysis occurs.

[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 between the surface heat flux and the thickness time history of the linear part material. The expression of the second sensitivity matrix J2 is:

[0110]

[0111] Step 403, determining a heat flow update formula according to the heat flow objective function, the time domain history of the thickness of the linear part material in the heat flow identification model, and the second sensitivity matrix.

[0112] Differentiate the heat flow objective function S(Q) with respect to Q and make it equal to 0, and substitute the Taylor expansion of D with respect to Q to obtain the heat flow update formula:

[0113]

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

[0115] Step 404, calculate the time domain history of the thickness of the linear part material in the heat flow identification model according to the initial value of the heat flow, the initial value of the 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.

[0116] The boundary conditions of the heat flow identification model can be set as follows: suppose the bottom coordinate of the heat flow identification model is x=0, then x=0 is the adiabatic boundary condition; the upper surface coordinate of the heat flow identification model is x=L, and heat flow is loaded at x=L, which is the heat flow boundary condition.

[0117] Specifically including steps S1 to S7:

[0118] Step S1, dividing the preset time period into multiple time steps, specifically, dividing the preset time period into t total The computation time of 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 space nodes; specifically, divide the space interval of the thickness time domain history L into N small intervals, then N+1 space nodes are obtained, and each small interval, that is, the space step length is:

[0121]

[0122] Step S3, updating the space in each time step and calculating 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, using a forward difference algorithm to update the time of each spatial node in the temperature field.

[0124] Specifically, the time derivatives are discretized 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, using a differential algorithm to update the position of each spatial node in the temperature field.

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

[0129]

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

[0131]

[0132] Step S6, obtaining the temperature of all spatial nodes in the heat flow identification model at all times according to the updated time and updated 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,

[0133] According to formulas (24), (25), and (26), formulas (4), (5), and (6) are updated to obtain:

[0134]

[0135] In order to simulate the mass loss process of the carbonized ablation material under the action of 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 is the thickness time domain history of the heat flow identification model at the n+1 time step, H(·) is the Heaviside function, defined as:

[0138]

[0139] Correspondingly, 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, is the temperature field of the heat flow identification model at n time steps and x=N*Δx, W1 is the temperature field of the heat flow identification model at x=1*Δx, and W0 is 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 is the initial temperature at time t=0.

[0145] Perform iterative calculations according to formulas (27), (28) and (29). According to the temperature of the spatial node at time step n, select formula (27) or formula (28) or formula (29) to calculate the temperature of the spatial node at time step n+1. Obviously, when n=0, the right side of the formula is completely known, and the left side can be calculated. The left side is the temperature of the right side after the time interval Δt. Perform N calculations for each time step, traversing all spatial nodes. There are M time steps in total, and a total of M*N calculations are performed to obtain the temperature of all spatial nodes at all times.

[0146] Step S7, obtaining the thickness time history of the linear part material in the heat flow identification model according to the temperature of all spatial nodes in the heat flow identification model at all times. The expression of the thickness time history D of the linear part material in the heat flow identification model is:

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

[0148] Among them, arg x For all such that W(x,t)=W fix The subset of x for which .

[0149] Step 405 , calculating the function value of the heat flow objective function according to the thickness time-domain history of the carbonized ablation material to be tested before pyrolysis and the thickness time-domain history of the linear part material in the heat flow identification model.

[0150] Step 406: 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 carbonization-type ablation material to be tested.

[0151] A heat flow stop criterion is set, wherein the heat flow stop criterion includes a second preset condition and a second stop preset value.

[0152] The function value of the heat flow objective function is less than the preset value, that is, the second stop preset value, and the expression is:

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

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

[0155] Step 407, if the function value of the heat flow objective function is greater than or equal to the preset value, the heat flow initial value is updated according to the heat flow update formula until the function value of the heat flow objective function meets the 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 the stop preset value.

[0156] If the function value of the heat flow objective function does not meet the heat flow stop criterion, that is, the function value of the heat flow objective function is greater than or equal to the preset value, the heat flow initial value is updated using the heat flow update formula (21), and the updated heat flow value becomes Q k+1 , the boundary conditions are changed accordingly, and the new boundary conditions become formula (34) until the function value of the heat flow objective function meets the second preset condition, and the thickness time domain history D of the linear part material in the new heat flow identification model is calculated according to the new boundary conditions k+1 .

[0157]

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

[0159] |S(Q k+1 )-S(Q k )|≤1% (38).

[0160] In an exemplary embodiment, a carbonized ablative material is used as an example to study the surface heat flow. According to the temperature time domain history of the bottom surface of the carbonized ablative material, the linear part is first solved to obtain the thickness time domain history of the thickness recognition model, such as Figure 4 As shown. Figure 4 It can be seen that the thickness time domain history of the thickness identification model has a high accuracy. The thickness time domain history result of the thickness identification model is used as input to solve the nonlinear part, such as Figure 5 As shown. Figure 5 It can be concluded that the identified surface heat flow is almost completely consistent with the actual heat flow, which shows the effectiveness of the surface heat flow identification method for carbonized ablative material provided by the present application. In order to more fully demonstrate the advantages of the surface heat flow identification method for carbonized ablative material provided by the present application, Figure 6 The comparison of the surface heat flow identification results of the carbonization-type ablative material surface heat flow identification method provided by the present application and the traditional method is shown in FIG.

[0161] Based on the same inventive concept, the embodiment of the present application also provides a carbonized ablative material surface heat flow identification device for implementing the carbonized ablative material surface heat flow identification method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more carbonized ablative material surface heat flow identification device embodiments provided below can refer to the limitations of the carbonized ablative material surface heat flow identification method above, and will not be repeated here.

[0162] In an exemplary embodiment, a device for identifying heat flow on the surface of a carbonized ablative material is provided, comprising:

[0163] The acquisition module is used to obtain the temperature time domain history of the bottom surface of the carbonization type ablation material to be tested within a preset time period.

[0164] A thickness solving module is used to solve the thickness time domain history of the carbonized ablation material to be tested when it has not been pyrolyzed according to the temperature time domain history and the thickness identification model; wherein the material properties of the thickness identification model are the same as the material properties of the carbonized ablation material to be tested when it has not been pyrolyzed, and the initial size of the thickness identification model is the same as the size of the carbonized ablation material to be tested when it has not been pyrolyzed, and the upper surface temperature of the thickness identification model is a fixed temperature, and the fixed temperature is the temperature at which the carbonized ablation material to be tested begins to pyrolyze.

[0165] The heat flow solving module is used to solve the surface heat flow of the carbonized ablative material to be tested according to the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed and the heat flow identification model, so as to obtain the surface heat flow of the carbonized ablative material to be tested; wherein 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 ablative material to be tested.

[0166] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 7As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for identifying the surface heat flow of a carbonized ablation material is implemented.

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

[0168] In an exemplary embodiment, a computer device is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0169] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0170] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[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, stored data, displayed data, 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 relevant data must comply with relevant regulations.

[0172] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present 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 may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0173] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0174] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for identifying heat flow on the surface of a carbonized ablative material, characterized in that: The method for identifying heat flow on the surface of a carbonized ablative material comprises: Obtaining the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period; Solving the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed according to the temperature time domain history and the thickness identification model; wherein the material properties of the thickness identification model are the same as the material properties of the carbonized ablative material to be tested when it has not been pyrolyzed, and the initial size of the thickness identification model is the same as the size of the carbonized ablative material to be tested when it has not been pyrolyzed, and the upper surface temperature of the thickness identification model is a fixed temperature, and the fixed temperature is the temperature at which the carbonized ablative material to be tested begins to pyrolyze; The surface heat flux of the carbonized ablative material to be tested is solved according to the thickness time domain history when the carbonized ablative material to be tested has not been pyrolyzed and the heat flow identification model, so as to obtain the surface heat flux of the carbonized ablative material to be tested; wherein the material properties of the heat flow identification model in the three stages of no pyrolysis, pyrolysis and completion of pyrolysis are the same as the material properties of the carbonized ablative material to be tested.

2. The method for identifying heat flow on the surface of carbonized ablative material according to claim 1, characterized in that: The heat transfer control equation of the thickness identification model is expressed as: The boundary condition expression of the thickness identification model is: W(d,t)=W fix ; Among them, W fix is 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 to be tested when it is not pyrolyzed, W(x, t) is the temperature field of the carbonized ablation material to be tested at time t with a thickness of 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 of the heat transfer control equations of the heat flow identification model and the corresponding temperature field conditions are: The boundary condition expression of the heat flow identification model is: Among them, ρ2, C2 and k2 are the density, specific heat and thermal conductivity of the carbonized ablation material to be tested during pyrolysis, ρ3, C3 and k3 are the density, specific heat and thermal conductivity of the carbonized ablation material to be tested at the stage of pyrolysis completion, C g is the specific heat of the gas generated by the pyrolysis of the carbonized ablation material to be tested, h g is the enthalpy value of the gas generated during the pyrolysis of the carbonized ablation material to be tested, are the gas mass flow rates generated by the carbonized ablation material during pyrolysis and at the completion of pyrolysis, W char is the pyrolysis completion temperature of the carbonized ablation material to be tested, W ablation 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 surface temperature of the carbonized material to be tested, L is the thickness time domain history of the heat flow identification model, and W(0,t) is the temperature time domain history of the heat flow identification model at x=0.

3. The method for identifying heat flow on the surface of carbonized ablative material according to claim 2, characterized in that: Solving the thickness time domain history of the carbonized ablative material to be tested when it is not pyrolyzed according to the temperature time domain history and the thickness identification model includes: Set the initial thickness time domain history of the thickness recognition model; Calculating the initial bottom surface temperature time domain history of the thickness identification model according to the initial thickness time domain history; The temperature objective function is constructed with the goal of minimizing the difference between the bottom surface temperature time domain history and the temperature time domain history; Determine a linear thickness update formula according to the temperature target function, the bottom surface temperature time domain history and the first sensitivity matrix; Calculating a function value of a temperature target function according to the initial bottom surface temperature time domain history and the temperature time domain history; If the function value of the temperature target function is less than a preset value, determining that the initial thickness time domain history is the thickness time domain history when the carbonization type ablative material to be tested has not been pyrolyzed; If the function value of the temperature objective function is greater than or equal to the preset value, the initial thickness time domain history is updated using the linear thickness update formula until the function value of the temperature objective function meets the first preset condition; wherein 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 the stop preset value.

4. The method for identifying heat flow on the surface of carbonized ablative material according to claim 3, characterized in that: Calculating the initial bottom surface temperature time domain history of the thickness identification model according to the initial thickness time domain history includes: Divide the preset time period into multiple time steps; Dividing the space corresponding to the initial thickness time domain history into a plurality of small intervals and a plurality of space nodes; The space is updated in 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; According to the updated time and updated 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 time domain history of the initial bottom surface temperature of the thickness identification model is obtained according to the temperatures of all spatial nodes in the thickness identification model at all times.

5. The method for identifying heat flow on the surface of carbonized ablative material according to claim 2, characterized in that: The surface heat flow of the carbonized ablative material to be tested is solved according to the thickness time domain history when the carbonized ablative material to be tested has not been pyrolyzed and the heat flow identification model to obtain the surface heat flow of the carbonized ablative material to be tested, including: Initializing the surface heat flux of the carbonization-type ablation material to be tested and the temperature field of the heat flux identification model to obtain the initial value of the heat flux and the initial value of the temperature field; Constructing a heat flow objective function with the goal of minimizing the difference between the thickness time-domain history of the carbonized ablation material to be tested when it is not pyrolyzed and the thickness time-domain history of the linear part material in the heat flow identification model; Determine a heat flow update formula according to the heat flow objective function, the thickness time history of the linear part material in the heat flow identification model, and the second sensitivity matrix; Calculate the thickness time domain history of the linear part material in the heat flow identification model according to the heat flow initial value, the temperature field initial 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; Calculate the function value of the heat flow objective function according to the thickness time-domain history of the carbonized ablation material to be tested when it is not pyrolyzed and the thickness time-domain history of the linear part material in the heat flow identification model; If the function value of the heat flow objective function is less than a preset value, determining the heat flow initial value as the surface heat flow of the carbonization type ablation material to be tested; If the function value of the heat flow objective function is greater than or equal to the preset value, the heat flow initial value is updated according to the heat flow update formula until the function value of the heat flow objective function meets the 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 the stop preset value.

6. The method for identifying heat flow on the surface of carbonized ablative material according to claim 5, characterized in that: The expression of the temperature objective function is: Among them, S(d) is the temperature objective function, d is the thickness time domain history of the thickness recognition model, Y(t) 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 recognition model, and T is the transpose of the matrix; The expression of the heat flow objective function is: Among them, S(Q) is the heat flow objective function, and D is the thickness time history of the linear part of the material in the heat flow identification model.

7. A device for identifying heat flow on the surface of a carbonized ablative material, characterized in that: The surface heat flow identification device of the carbonization type ablative material comprises: An acquisition module, used to acquire the temperature time domain history of the bottom surface of the carbonized ablation material to be tested within a preset time period; A thickness solving module, used for solving the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed according to the temperature time domain history and the thickness identification model; wherein the material properties of the thickness identification model are the same as the material properties of the carbonized ablative material to be tested when it has not been pyrolyzed, and the initial size of the thickness identification model is the same as the size of the carbonized ablative material to be tested when it has not been pyrolyzed, and the upper surface temperature of the thickness identification model is a fixed temperature, and the fixed temperature is the temperature at which the carbonized ablative material to be tested begins to pyrolyze; The heat flow solving module is used to solve the surface heat flow of the carbonized ablative material to be tested according to the thickness time domain history of the carbonized ablative material to be tested when it has not been pyrolyzed and the heat flow identification model, so as to obtain the surface heat flow of the carbonized ablative material to be tested; wherein 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 ablative material to be tested.

8. A computer device comprising: 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 method for identifying the surface heat flow of a carbonized ablative material according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for identifying the surface heat flow of a carbonized ablative material according to any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for identifying the surface heat flow of a carbonized ablative material according to any one of claims 1 to 6 is implemented.

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