A fast calculation method of three-dimensional elliptical distribution temperature field mass grid

Abstract

The application provides a fast calculation method of a three-dimensional elliptical distribution temperature field mass grid, comprising the following steps: S1: according to the irradiation direction of a temperature field heat source, two two-dimensional sections are selected in a three-dimensional grid of a test plate, and two-dimensional temperature field numerical simulation is carried out on the two-dimensional sections; S2: a series of virtual concentric ellipses are inserted as interpolation lines in the three-dimensional grid of the test plate layer by layer along the thickness direction of the test plate, and the interpolation lines are valued according to the numerical simulation results of the two-dimensional sections; S3: one point P on a plane of one layer in the thickness direction of the test plate is sequentially selected, and the shortest distances from the point P to the adjacent two interpolation lines are calculated; S4: linear interpolation or linear extrapolation is carried out on the temperature at the point P; and S5: the steps S3-S4 are repeatedly executed until the calculation states of all points on all layers in the thickness direction of the test plate are completed. Through the fast calculation method of the three-dimensional elliptical distribution temperature field mass grid, the problem of slow numerical simulation calculation speed of the mass three-dimensional grid is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of numerical simulation, in particular to a fast calculation method of three-dimensional elliptical distribution temperature field mass grid. BACKGROUND

[0002] Reflective thermal insulation coating is an important functional coating for the surface of ship hulls, oil and gas equipment, buildings and other facilities, which can effectively reflect and block the energy of solar radiation, reduce the temperature of the facility surface from the source, and prevent heat transfer to the interior of the facility. At present, people mostly use the self-made simple reflective thermal insulation temperature difference test device according to the US military standard MIL-E-46136 to test, and the design of each device is quite different. The test results of the reflective thermal insulation coating are often not comparable, and only the existing sample plates of certain thickness can be tested, which has a long test period, high cost, and is not conducive to the accelerated development of reflective thermal insulation coating research.

[0003] Numerical simulation refers to a numerical analysis method that uses a computer to solve the approximate solution of a model by combining numerical methods such as finite elements and finite differences. When performing numerical simulation, the continuous distribution of the object to be solved over time and space is generally first discretized, and then the differential equation is converted into a linear algebraic equation system for solving. Numerical simulation can reveal the distribution and evolution law of temperature field, stress field and other fields, greatly shorten the test period, save experimental cost, and guide the optimization of formula, process and other aspects, and has a wide application in scientific research and production. Numerical simulation of the temperature field of the reflective thermal insulation coating sample plate is an effective virtual test method for studying the thermal insulation temperature difference of the reflective thermal insulation coating.

[0004] HG / T 4341-2012 Hot Reflective Thermal Insulation Coatings for Metal Surfaces describes a method for testing the thermal insulation temperature difference: (1) At room temperature, a 500-1000W infrared heating lamp is used as a heat source to irradiate the test plate (the coating is a few tens of microns to a few hundred microns of paint film; the substrate is a millimeter-thick carbon steel, aluminum alloy, etc.) for 1h (or longer), simulate the temperature field of the test plate, and obtain the temperature of the lower surface of the substrate; (2) Under the same conditions, simulate the temperature field of the blank test plate (bare substrate), and obtain the temperature of the lower surface of the blank test plate; (3) Use ΔT = T 空 -T 试 The thermal insulation performance of the coating is evaluated. Since the test plate is a regular cuboid, its upper surface receives approximately uniform irradiation from the infrared lamp, and the other surfaces exchange heat with the environment by convection. It can be seen that the temperature field of each cross section in the thickness direction of the test plate is elliptically distributed.

[0005] In the prior art, mesh plays an important role in numerical simulation, and mainstream numerical simulation methods such as finite difference, finite volume, finite element and boundary element are all based on mesh as a calculation object. Under the premise of ensuring mesh quality, the number of meshes is generally considered according to the computing resources in general research and engineering, and high-precision calculation results must come from high-density meshes. However, the processing capacity of PC for massive three-dimensional (billion and above) meshes is weak, and the calculation speed is slow, which restricts the application of numerical simulation in high-precision micro-size multi-mesh cases. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to provide a fast calculation method for massive meshes of a three-dimensional elliptical distribution temperature field, aiming at solving the problem of slow numerical simulation calculation speed for massive three-dimensional meshes in the prior art, and making it possible to rely on PC for high-precision numerical simulation of the heat insulation temperature difference of reflective heat insulation coating.

[0007] To solve the above technical problems, the present application provides a fast calculation method for massive meshes of a three-dimensional elliptical distribution temperature field, comprising the following steps:

[0008] S1: According to the irradiation direction of the temperature field heat source, two two-dimensional sections are selected in the three-dimensional mesh of the test plate, the two-dimensional temperature field numerical simulation is carried out on the two-dimensional sections, and the numerical simulation results are obtained;

[0009] S2: A series of virtual concentric ellipses are inserted as interpolation lines in the three-dimensional mesh of the test plate along the thickness direction of the test plate, and the interpolation lines are valued according to the numerical simulation results of the two-dimensional sections;

[0010] S3: A point P on a plane in the thickness direction of the test plate is sequentially selected, and the shortest distances from the point P to its adjacent two interpolation lines are calculated;

[0011] S4: Linear interpolation or linear extrapolation is performed on the temperature at the point P;

[0012] S5: Steps S3-S4 are repeated until the calculation state of all points on all layers in the thickness direction of the test plate is completed;

[0013] S6: The three-dimensional temperature field results of all points are output.

[0014] Preferably, in step S1, corresponding to the three-dimensional Cartesian coordinate system of the three-dimensional mesh, the thickness direction of the test plate is set as the X-axis direction, and according to the distribution of the temperature field simulation boundary condition, the XOY and XOZ central sections of the cuboid test plate are selected for numerical simulation calculation of the heat transfer process temperature field.

[0015] Preferably, the assigning of the interpolation line in step S2 comprises setting the semi-major axis a[i] and / or semi-minor axis b[i] of the elliptical interpolation line according to the geometric size of the three-dimensional grid.

[0016] Preferably, step S3 comprises the following specific operation steps:

[0017] S31: sequentially selecting a YOZ plane in the thickness direction of the test plate in a three-dimensional Cartesian coordinate system;

[0018] S32: sequentially selecting one target point P(y, z) on the YOZ plane;

[0019] S33: judging whether the target point P(y, z) is located outside the largest virtual ellipse on the YOZ plane;

[0020] S34: if yes, calculating the shortest distance d m from the target point P(y, z) to the largest ellipse and the shortest distance d m-1 from the target point P(y, z) to the next outer ellipse, respectively; if no, calculating the shortest distance d i from the target point P(y, z) to the i-th ellipse and the shortest distance d i+1 from the target point P(y, z) to the (i+1)-th ellipse, respectively.

[0021] Preferably, in step S3, if there is an analytical solution for the shortest distance from the point P to the interpolation line, the analytical method is used for solving, if there is no analytical solution for the shortest distance from the point P to the interpolation line or there is an analytical solution but the analytical difficulty is greater than a preset difficulty, the numerical solving method is used for solving.

[0022] Preferably, in step S34, the shortest distance d i from the target point P(y, z) to the i-th ellipse is solved by the following numerical solving method:

[0023] S341: calculating the angle θ of the line connecting the target point P(y, z) and the center point (y0, z0) of the ellipse and the horizontal axis Y, and the calculation formula is as follows:

[0024]

[0025] S342: dividing the interval (θ-α, θ+α) into N small intervals, and the angle size of each small interval is Taking α=15°, N is calculated by the following formula:

[0026] N=[(PI·a[i]·b[i])];

[0027] S343: Take N points on the i-th ellipse, with corresponding coordinates (a[i]·cos(τ[i]), b[i]·sin(τ[i])), where the value of τ[i] is calculated using the following formula:

[0028]

[0029] S344: Select one of these N points sequentially, and the distance d′ from the target point P(y, z) to that point. i Calculate using the following formula:

[0030]

[0031] S345: Calculate d′ corresponding to these N points. i After calculating the values, compare and select the smallest d′. i The value is used as the shortest distance d from the target point P(y, z) to the i-th ellipse. i Numerical solution.

[0032] Preferably, step S4 includes the following specific calculation steps:

[0033] S41: Determine whether the target point P(y, z) is located within the largest virtual ellipse on the selected YOZ plane;

[0034] S42: If so, based on the di and di+1 values ​​of the target point P(y, z), determine the temperature T of the target point P(y, z). (y，z) Performing linear interpolation, we get:

[0035]

[0036] Among them, T i and T i+1 Let be the temperatures of the i-th ellipse and the (i+1)-th ellipse, respectively;

[0037] S43: If not, based on the d of the target point P(y, z) m value and d m-1 The value of the temperature T at the target point P(y, z). (y，z) Performing linear extrapolation, we get:

[0038]

[0039] Among them, T m and T m-1 These are the temperatures of the largest and second-largest ellipse, respectively.

[0040] Preferably, step S6 outputs a three-dimensional temperature field file in Tecplot data format, which includes at least the three-dimensional coordinates and temperature values ​​of each grid.

[0041] Preferably, in combination with the heat insulation temperature difference numerical simulation of the reflective heat insulation coating, step S1 comprises the following specific operation steps:

[0042] S11: According to the irradiation direction of the temperature field heat source, the test plate is divided into a uniform grid, and a two-dimensional temperature field is solved by using a finite difference method explicit format;

[0043] S12: Corresponding to the three-dimensional Cartesian coordinate system of the three-dimensional divided grid, the thickness direction of the test plate is set as the X-axis direction, and according to the boundary condition distribution of the temperature field simulation, the XOY and XOZ central sections of the cuboid test plate are selected for numerical simulation calculation of the heat transfer process temperature field.

[0044] Preferably, in the heat insulation temperature difference numerical simulation of the reflective heat insulation coating, the test plate size is 300mm*200mm*2mm, the coating thickness is 0.1mm, the divided grid size is 20um, the total grid number is 1550000000, the explicit solving method is adopted, and the maximum time step is 7.8*10 -6 s.

[0045] Compared with the prior art, the three-dimensional elliptical distribution temperature field mass grid fast calculation method has the following beneficial effects:

[0046] The existing numerical simulation calculation method has a high demand for computer computing power when processing a mass (such as a billion and above) three-dimensional grid, and the calculation speed is slow. The method can greatly reduce the calculation amount without changing the grid size, and can quickly obtain a three-dimensional numerical simulation result under the premise of ensuring high accuracy, thereby providing a new idea for high-precision numerical simulation of a three-dimensional high-density micro-size mass grid. BRIEF DESCRIPTION OF DRAWINGS

[0047] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The illustrations among the drawings serve to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0048] Figure 1 FIG. 1 is a flowchart of a three-dimensional elliptical distribution temperature field mass grid fast calculation method according to an embodiment of the present application;

[0049] Figure 2 FIG. 2 is a schematic diagram of the position and coordinate system of a substrate-reflective heat insulation coating according to an embodiment of the present application;

[0050] Figure 3 FIG. 3 is a schematic diagram of selecting an XOY central section and an XOZ central section according to an embodiment of the present application;

[0051] Figure 4A distribution diagram of the inserted virtual ellipse in the three-dimensional grid for the series of virtual ellipses described in Embodiment 1 of the present application;

[0052] Figure 5 For Figure 4 A distribution diagram of the inserted virtual ellipse in the YOZ plane corresponding to any layer grid in the thickness direction (X-axis) of the test plate;

[0053] Figure 6 A solving flowchart of solving the shortest distance from a point to an ellipse by using a numerical solving method for one of the virtual ellipses described in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned objects, technical solutions and advantages of the present application more clear and easy to understand, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein of the present application only constitute part of the embodiments of the present application, which are only used to explain the present application and do not constitute a limitation on the present application. In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0055] Embodiment 1

[0056] Referring to Figures 1-6 As shown in the drawings, the present application proposes a fast calculation method of three-dimensional ellipse distribution temperature field mass grid, comprising the following steps:

[0057] S1: According to the irradiation direction of the temperature field heat source, two two-dimensional sections (XOY, XOZ) are selected in the three-dimensional grid of the test plate, the two-dimensional temperature field numerical simulation is carried out on the two-dimensional sections, and the numerical simulation results are obtained;

[0058] S2: A series of virtual concentric ellipses are inserted as interpolation lines in the three-dimensional grid of the test plate along the thickness direction (X-axis) of the test plate, and the interpolation lines are valued according to the numerical simulation results of the two-dimensional sections (XOY, XOZ);

[0059] S3: A point P on a layer plane (YOZ plane) in the thickness direction (X-axis) of the test plate is sequentially selected, and the shortest distances from the point P to its adjacent two interpolation lines are calculated respectively;

[0060] S4: The temperature at the point P is linearly interpolated or linearly extrapolated;

[0061] S5: Steps S3-S4 are repeatedly executed until the calculation state of all points on all layers in the thickness direction (X-axis) of the test plate is completed;

[0062] S6: The three-dimensional temperature field results of all points are output.

[0063] Specifically, the existing numerical simulation calculation method has high demand for computer computing power when processing massive (such as the order of one billion and above) three-dimensional grids, and the calculation speed is slow, the present application converts three-dimensional numerical simulation into two-dimensional numerical simulation and then interpolates to obtain three-dimensional numerical simulation results, which can ensure high calculation precision and greatly reduce the calculation amount and speed up the calculation efficiency without changing the grid size, providing a new idea for high-precision numerical simulation of three-dimensional high-density micro-size massive grids.

[0064] Taking a PC with CPU i7 12700H / 20 threads and RAM 16G as an example, the traditional finite difference method needs thousands of hours to calculate the temperature field of the same model, while the three-dimensional elliptical distribution temperature field massive grid fast calculation method provided by the present application only needs more than ten hours, and the calculation efficiency is improved by hundreds of times.

[0065] Therefore, the three-dimensional elliptical distribution temperature field massive grid fast calculation method can effectively solve the problem of slow numerical simulation calculation speed for massive three-dimensional grids in the prior art, and make it possible to rely on PC for high-precision numerical simulation of the heat insulation temperature difference of reflective heat insulation coating.

[0066] Preferably, in step S1, corresponding to the three-dimensional Cartesian coordinate system of the three-dimensional grid, the thickness direction of the test plate is set as the X-axis direction, and the XOY and XOZ central sections of the cuboid test plate are selected for numerical simulation calculation of the temperature field in the heat transfer process according to the boundary condition distribution of the temperature field.

[0067] Specifically, in step S1, the selection of the two-dimensional section needs to be appropriate so as to assign values to the interpolation line according to the numerical simulation results of the two-dimensional section in subsequent step S2. As one of the preferred examples of step S1, when the thickness direction of the test plate is set as the X-axis direction, the XOY and XOZ central sections of the cuboid test plate can be selected for numerical simulation calculation of the temperature field in the heat transfer process.

[0068] More specifically, in combination with the numerical simulation of the heat insulation temperature difference of the reflective heat insulation coating, the test plate can be first divided into uniform grids. The position and coordinate system of the substrate-heat insulation coating can be as shown in Figure 2 , wherein the thickness direction of the test plate (X-axis) corresponds to the irradiation direction of the heat source of the temperature field, the substrate size is 300mmx200mmx2mm, the coating thickness is 0.1mm, the grid size is 20μm, the total number of grids is 1550000000, the explicit solution method is adopted, and the maximum time step is 7.8x10 -6 s. Further, the two-dimensional section is selected as Figure 3As shown, the finite difference method explicit format is used for two-dimensional temperature field numerical simulation calculation of the XOY plane and the XOZ plane of the test plate, and then the two-dimensional temperature field simulation calculation result of the virtual concentric ellipse can be obtained in the subsequent step S2.

[0069] Preferably, the step S2 of assigning the interpolation line includes setting the semi-major axis a[i] and / or the semi-minor axis b[i] of the elliptical interpolation line according to the geometric size of the three-dimensional grid.

[0070] Specifically, referring to Figures 4-5 As shown, for the y direction, the semi-major axis of the i-th ellipse is obtained per unit length, and the semi-major axis is recorded in the array a[i]; for the z direction, the semi-minor axis of the i-th ellipse is set according to the geometric length ratio of the y axis and the z axis and is recorded in the array b[i]. Wherein, the numerical result of the grid point in the long axis direction of the ellipse is known, and the numerical result of the grid point in the short axis direction of the ellipse can be obtained by linear interpolation of adjacent grid points.

[0071] Preferably, the step S3 includes the following specific operation steps:

[0072] S31: In the three-dimensional Cartesian coordinate system, sequentially select a YOZ plane along the thickness direction (X axis) of the test plate;

[0073] S32: Sequentially select one target point P(y,z) on the YOZ plane of the layer;

[0074] S33: Determine whether the target point P(y,z) is located outside the largest virtual ellipse on the YOZ plane of the layer;

[0075] S34: If yes, calculate the shortest distance d m of the target point P(y,z) to the largest ellipse m-1 and the shortest distance d i of the target point P(y,z) to the next outer ellipse; if not, calculate the shortest distance d i+1 of the target point P(y,z) to the i-th ellipse and the (i+1)-th ellipse adjacent to the inside and outside, respectively.

[0076] As one of the preferred embodiments of the step S3, if the shortest distance of the point P to the interpolation line has an analytical solution, the analytical method is used for solving, if the shortest distance of the point P to the interpolation line does not have an analytical solution, or although it has an analytical solution but the analytical difficulty is greater than the preset difficulty, the numerical solving method is used for solving.

[0077] Specifically, the analytical solution refers to the solution obtained by strict formula, and the calculation accuracy is slightly higher than the numerical solution. Under the premise of ensuring high calculation accuracy, the calculation amount can be greatly reduced and the calculation efficiency can be improved.

[0078] Preferably, referring to Figure 6As shown, in step S34, the shortest distance d from the target point P(y, z) to its adjacent i-th ellipse is... i The following numerical solution method is used to solve the problem:

[0079] S341: Calculate the angle θ between the line connecting the target point P(y, z) and the center point (y0, z0) of the ellipse and the horizontal Y-axis. The calculation formula is as follows:

[0080]

[0081] S342: Divide the interval (θ-α, θ+α) into N equal subintervals, where the angle of each subinterval is... Taking α = 15°, N is calculated using the following formula:

[0082] N = [(PI·[i]·b[i])];

[0083] S343: Take N points on the i-th ellipse, with corresponding coordinates (a[i]·cos(τ[i]), b[i]·sin(τ[i])), where the value of τ[i] is calculated using the following formula:

[0084]

[0085] S344: Select one of these N points sequentially, and the distance d′ from the target point P(y, z) to that point. i Calculate using the following formula:

[0086]

[0087] S345: Calculate d′ corresponding to these N points. i After calculating the values, compare and select the smallest d′. i The value is used as the shortest distance d from the target point P(y, z) to the i-th ellipse. i Numerical solution.

[0088] Specifically, through steps S341 to S345, this invention also proposes a numerical method for solving the shortest distance from point P to its adjacent elliptical interpolation line. It can be understood that in step S34, this numerical method not only applies to d... i Numerical solutions are applicable, but in practice, for d i+1 d m d m-1 Any one of them applies equally.

[0089] Preferably, step S4 includes the following specific calculation steps:

[0090] S41: Determine whether the target point P(y, z) is located within the largest virtual ellipse on the selected YOZ plane;

[0091] S42: If so, based on the target point P(y, z), d i value and d i+1 The value of the temperature T at the target point P(y, z). (y，z) Performing linear interpolation, we get:

[0092]

[0093] Among them, T i and T i+1 Let be the temperatures of the i-th ellipse and the (i+1)-th ellipse, respectively;

[0094] S43: If not, based on the d of the target point P(y, z) m value and d m-1 The value of the temperature T at the target point P(y, z). (y，z) Performing linear extrapolation, we get:

[0095]

[0096] Among them, T m and T m-1 These are the temperatures of the largest and second-largest ellipse, respectively.

[0097] Specifically, through further interpolation calculation of the temperature at point P in step S4, the temperature calculation results on the virtual ellipse corresponding to step S2 will be interpolated to obtain the temperature field T on each YOZ plane. (y，z) Repeat step S3 to obtain the temperature field T based on the YOZ plane of each layer. (y，z) The results of the three-dimensional numerical simulation are shown. Among them, the interpolation calculation for the target point P(y,z) is further subdivided into linear interpolation or linear extrapolation, which can ensure the smoothness of the three-dimensional numerical simulation results and prevent abnormal situations such as sudden changes in the numerical simulation results.

[0098] Preferably, step S6 outputs a three-dimensional temperature field file in Tecplot data format, which includes at least the three-dimensional coordinates and temperature values ​​of each grid.

[0099] Specifically, this invention has a wide range of applications and can be used in high-precision numerical simulations of three-dimensional high-density micro-sized massive meshes in multiple fields. It can also be used simultaneously with other algorithm optimization methods to further accelerate computation.

[0100] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A fast calculation method of three-dimensional elliptical distribution temperature field mass grid, characterized in that, Comprising the following steps: S1: According to the irradiation direction of the temperature field heat source, two two-dimensional sections are selected in the three-dimensional grid of the test plate, the two-dimensional temperature field numerical simulation is carried out on the two-dimensional sections, and the numerical simulation result is obtained; S2: Along the thickness direction of the test plate, a series of virtual concentric ellipses are inserted as interpolation lines in the three-dimensional grid of the test plate layer by layer, and the interpolation lines are valued according to the numerical simulation result of the two-dimensional section temperature field; S3: A point P on a plane in the thickness direction of the test plate is sequentially selected, and the shortest distances from the point P to its adjacent two interpolation lines are calculated respectively; S4: Linear interpolation or linear extrapolation is performed on the temperature at the point P; Step S4 comprises the following specific operation steps: S41: Determine whether the target point P(y, z) is located within the largest virtual ellipse on the selected YOZ plane; S42: If yes, the temperature of the target point P(y, z) is linearly interpolated according to the d i value and the d i+1 value of the target point P(y, z), and the result is: ； wherein, T1and T2are the temperatures of the i-th and (i+1)-th ellipses, respectively. S43: If not, based on the d of the target point P(y,z) m value and d m-1 Value, for the temperature at target point P(y,z) Performing linear extrapolation, we get: ； wherein, Tmax and Tmin are the temperature of the largest and second largest ellipse, respectively. S5: Steps S3-S4 are repeatedly executed until the calculation state of all points on all layers in the thickness direction of the test plate is completed; S6: Output the three-dimensional temperature field result of all points.

2. The method of claim 1, wherein, In step S1, corresponding to the three-dimensional Cartesian coordinate system of the three-dimensional grid, the thickness direction of the test plate is set as the X-axis direction, and according to the distribution of the temperature field simulation boundary condition, the XOY and XOZ two central sections of the cuboid test plate are selected for numerical simulation calculation of the temperature field in the heat transfer process.

3. The method of claim 2, wherein the three-dimensional elliptical temperature field mass grid is calculated rapidly. The interpolation line valuation in step S2 includes: setting the semi-major axis a[i] and / or semi-minor axis b[i] of the ellipse interpolation line according to the geometric size of the three-dimensional grid.

4. The method of claim 3, wherein the three-dimensional elliptical temperature field mass grid is calculated rapidly. Step S3 comprises the following specific operation steps: S31: In the three-dimensional Cartesian coordinate system, a YOZ plane in the thickness direction of the test plate is sequentially selected; S32: A target point P(y, z) on the YOZ plane is sequentially selected; S33: Determine whether the target point P(y, z) is located outside the largest virtual ellipse on the YOZ plane. S34: If yes, calculate the shortest distance d of the target point P(y, z) to the maximum ellipse m and the shortest distance d of the target point P(y, z) to the next outer ellipse m-1 ; if no, calculate the shortest distance d of the target point P(y, z) to the i-th ellipse and the shortest distance d of the target point P(y, z) to the (i+1)-th ellipse i and d i+1 , which are adjacent to the inside and outside of the ellipse, respectively.

5. The method of claim 4, wherein the three-dimensional elliptical temperature field mass grid is calculated rapidly. In step S3, if there is an analytical solution for the shortest distance from the point P to the interpolation line, the analytical method is used for solving, if there is no analytical solution for the shortest distance from the point P to the interpolation line, or although there is an analytical solution but the analytical difficulty is greater than the preset difficulty, the numerical solving method is used for solving.

6. The method of claim 5, wherein the three-dimensional elliptical temperature field mass grid is calculated quickly. In step S34, the shortest distance d of the target point P(y, z) to its adjacent i-th ellipse i is solved by using the following numerical solution method: S341: Calculate the angle of the line connecting the target point P(y, z) and the ellipse center point (y0, z0) with the horizontal axis Y-axis The calculation formula is as follows: ； S342: divide the interval ( , ) into N sub-intervals, and the angle size corresponding to each sub-interval is , and , then N is calculated as follows: ； S343: Take N points on the i-th ellipse, and the corresponding coordinates are wherein The value of is calculated by the following formula: ； S344: sequentially select one of the N points, the distance d' from the target point P(y,z) to the point i The following formula is used for calculation: ； S345: After calculating the d' of the N points, compare and select the minimum d' as the numerical solution of the shortest distance d i from the target point P(y,z) to the i-th ellipse. i i ​​ 7. The method of claim 1, wherein the three-dimensional elliptical temperature field mass grid is calculated rapidly. The three-dimensional temperature field file output in step S6 is in tecplot data format, and at least contains three-dimensional coordinate and temperature value information of each grid.

8. The method of claim 1-6, wherein, In combination with the numerical simulation of the heat insulation temperature difference of the reflective heat insulation coating, step S1 comprises the following specific operation steps: S11: According to the irradiation direction of the temperature field heat source, the cuboid test plate is divided into uniform grid, and the two-dimensional temperature field is solved by using the finite difference method explicit format; S12: Corresponding to the three-dimensional Cartesian coordinate system of the three-dimensional divided grid, the thickness direction of the test plate is set as the X-axis direction, and according to the distribution of the temperature field simulation boundary condition, the XOY and XOZ two central sections of the cuboid test plate are selected for numerical simulation calculation of the temperature field in the heat transfer process.

9. The method of claim 8, wherein the three-dimensional elliptical temperature field mass grid is calculated rapidly. In the simulation of the heat insulation temperature difference of the reflective heat insulation coating, the size of the test plate is 300mm×200mm×2mm, the coating thickness is 0.1mm, the size of the sectioned grid is 20μm, the total number of grids is 1550000000, the explicit format solving method is adopted, and the maximum time step is 7.8×10 -6 s.

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