A method for predicting pressure drop in layered porous structures along the heat source direction

Abstract

The present invention belongs to the technical field of porous structure heat exchangers and proposes a method for predicting the pressure drop of a layered porous structure along the direction of a heat source. The method comprises establishing physical models of single-porosity porous structures of different specifications, calculating the pressure drop of each single-porosity porous structure at different inlet fluid velocities, and establishing a model between the inlet fluid velocity and pressure drop of a single-porosity porous structure; constructing a layered porous structure model, determining the total inlet fluid flow rate, and determining the actual flow rate of each layer of single-porosity porous structure in the layered porous structure model; obtaining the actual inlet fluid velocity and actual pressure drop of each layer of single-porosity porous structure; averaging the actual pressure drops of each layer of single-porosity porous structure to obtain the pressure drop of a layered gradient porous structure along the direction of a heat source. The present invention comprehensively considers the actual flow rate and actual velocity of each single-porosity porous structure, greatly reducing experimental and simulation costs and improving prediction speed.

Description

Technical Field

[0001] The invention belongs to the technical field of porous structure heat exchangers, and specifically discloses a method for predicting the pressure drop of a layered porous structure along a heat source direction. Background Art

[0002] As a new type of compact heat exchanger, porous structure heat exchangers have shown great application potential in thermal management systems of devices such as aircraft, high-speed ships and high-speed trains due to their unique structure and excellent heat transfer performance. However, porous structure heat exchangers face a problem that needs to be solved in practical applications, namely the large pressure drop, which seriously limits the widespread application of porous structure heat exchangers. In the design and optimization process of porous structure heat exchangers, pressure drop is one of the key factors affecting their performance. Excessive pressure drop not only increases the energy consumption of the system, but also reduces the heat transfer efficiency, thereby weakening the advantages of the heat exchanger in the thermal management system. In order to reduce the pressure drop while maintaining the efficient heat transfer performance of the heat exchanger, changing the arrangement of the porous structure along the heat source direction while ensuring that the overall porosity remains unchanged has been proven to be an effective method. This arrangement can improve the fluid flow characteristics, thereby reducing the pressure drop and improving the overall heat transfer performance.

[0003] However, there are still obvious deficiencies in the prediction of pressure drop for layered gradient porous structures arranged along the direction of the heat source. Existing pressure drop prediction methods mainly rely on simulation or experimental means. Although simulation methods can simulate the fluid flow and pressure drop characteristics of porous structures to a certain extent, their accuracy and reliability are limited by various factors such as model assumptions, calculation accuracy, and boundary conditions. Experimental methods require a large amount of experimental equipment, time, and manpower investment, and the universality of experimental results is limited, making it difficult to directly apply them to the design of heat exchangers with different working conditions and structures. Therefore, whether it is through simulation or experimental means to obtain pressure drop data for non-uniform structures, it takes a lot of time and money, which undoubtedly increases the difficulty of research and development and optimization of porous structure heat exchangers, and limits their wide application in actual engineering.

[0004] In summary, the existing technology lacks an effective and efficient method for predicting the pressure drop of layered porous structures arranged along the direction of the heat source. The lack of such a prediction method makes it difficult to quickly and accurately evaluate the pressure drop performance of different structural arrangement schemes during the design and optimization of porous structure heat exchangers, which in turn affects the performance optimization and promotion of heat exchangers. Therefore, developing a method that can quickly and accurately predict the pressure drop of layered porous structures arranged along the direction of the heat source is of great practical significance for promoting the widespread application of porous structure heat exchangers in thermal management systems of devices such as aircraft, high-speed ships and high-speed trains. Summary of the Invention

[0005] In order to solve the problems in existing layered porous structure pressure drop prediction, such as complex prediction methods, high costs and inability to make rapid and accurate predictions, the present invention proposes a pressure drop prediction method for layered porous structures along the heat source direction.

[0006] The present invention provides a method for predicting the pressure drop of a layered porous structure along a heat source direction, comprising the following steps:

[0007] S1. Establishing physical models of porous structures of different single porosity specifications, respectively, calculating the pressure drop of each porous structure of the single porosity at different inlet fluid velocities, and establishing a model between the inlet fluid velocity and pressure drop of the porous structure of the single porosity;

[0008] S2. Constructing a hierarchical porous structure model, confirming the total flow rate of the inlet fluid flowing into the hierarchical porous structure model, and confirming the actual flow rate of each layer of the hierarchical porous structure model with a single porosity;

[0009] S3. Determine the actual inlet fluid velocity of each layer of the single-porosity porous structure based on the actual flow rate of each layer of the single-porosity porous structure obtained in step S2, and determine the actual pressure drop of each layer of the single-porosity porous structure in the layered porous structure model based on the model between the inlet fluid velocity and pressure drop of the single-porosity porous structure obtained in step S1;

[0010] S4. averaging the actual pressure drops of the porous structures with a single porosity in each layer obtained in step S3 to obtain the pressure drop of the layered gradient porous structure along the heat source direction.

[0011] According to a method for predicting the pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S1, the single porosity porous structure is selected from one of a Weaire-Phelan lattice structure, a Kelvin lattice structure, and a BCC lattice structure.

[0012] According to a method for predicting a pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S1, the porosity range of the single-porosity porous structure is: 0.7~0.95.

[0013] According to a method for predicting the pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S1, the model between the inlet fluid velocity and the pressure drop of the porous structure with a single porosity is shown in formula (1):

[0014] (1)

[0015] in, It represents the pressure drop per unit length, represents the inlet fluid velocity, represents a linear constant, represents the quadratic constant.

[0016] According to a method for predicting the pressure drop of a layered porous structure along the direction of a heat source in some embodiments of the present application, in step S2, the layered porous structure model is formed by stacking single-porosity porous structures of different porosities along the direction of the heat source, and the connecting rods of two layers of single-porosity porous structures are in a stepped transition or a smooth transition.

[0017] According to a method for predicting a pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S2, the total flow rate of the inlet fluid flowing into the layered porous structure model is as shown in formula (2):

[0018] (2)

[0019] in, represents the total inlet fluid flow rate of the layered porous structure model, represents the fluid density, represents the inlet fluid velocity, Indicates the fluid inlet cross-sectional area.

[0020] According to a method for predicting the pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S2, the actual flow rate of each layer of the single porosity porous structure in the layered porous structure model is as shown in formula (3) and formula (4):

[0021] (3)

[0022] (4)

[0023] in, represents the total inlet fluid flow of the layered porous structure model, represents the actual flow rate entering the first layer of the single porosity porous structure, represents the actual flow rate entering the second layer of the single porosity porous structure, represents the pressure drop of the first layer of a single porosity porous structure, Represents the pressure drop of the second layer of the single porosity porous structure.

[0024] According to a method for predicting a pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S3, the actual inlet fluid velocity of each layer of the single-porosity porous structure obtained in step S2 is obtained as shown in formulas (5) and (6):

[0025] (5)

[0026] (6)

[0027] in, represents the actual inlet fluid velocity of the first layer of the single porosity porous structure, represents the actual flow rate entering the first layer of the single porosity porous structure, represents the total inlet fluid flow of the layered porous structure model, represents the inlet fluid velocity, represents the actual inlet fluid velocity of the second layer of the single porosity porous structure, Represents the actual flow rate entering the second layer of single porosity porous structure.

[0028] According to a method for predicting the pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S3, the pressure drop of each layer of a single porosity porous structure in the layered porous structure model is obtained as shown in formula (7) and formula (8):

[0029] (7)

[0030] (8)

[0031] in, represents the actual pressure drop of the first layer of the porous structure with a single porosity, The linear constant representing the first layer of the porous structure with a single porosity, represents the actual inlet fluid velocity of the first layer of the single porosity porous structure, represents the quadratic constant of the first layer of single porosity porous structure, represents the actual pressure drop of the second layer of the single porosity porous structure, represents the linear constant of the second layer single porosity porous structure, represents the actual inlet fluid velocity of the second layer of the single porosity porous structure, The quadratic constant representing the second layer of the single porosity porous structure.

[0032] According to a method for predicting the pressure drop of a layered porous structure along a heat source direction in some embodiments of the present application, in step S4, the pressure drop of the layered gradient porous structure along the heat source direction is as shown in formula (9):

[0033] (9)

[0034] in, represents the pressure drop of the layered gradient porous structure along the heat source direction, represents the actual pressure drop of the first layer of the porous structure with a single porosity, It represents the actual pressure drop of the second layer of the single porosity porous structure.

[0035] The present invention proposes a method for predicting the pressure drop of a layered porous structure along the direction of a heat source. Based on the pressure drop of a porous structure with a uniform single porosity, the method can quickly and accurately predict the pressure drop of layered porous structures arranged along the direction of a heat source in a variety of gradient ranges. The method does not require simulation means and experimental means, which greatly reduces the experimental and simulation costs. The method can also quickly and effectively determine the actual flow rate of each layer of the layered porous structure based on the pressure drop of the porous structure with a single porosity, and then determine the actual inlet fluid velocity of each layer of the layered porous structure, providing a basis for research that needs to be based on this parameter. The data obtained by the prediction method of the present invention is in good agreement with the simulation data, with a maximum error of less than 2.5%. It can be widely used in the design of engineering porous structure flow devices, such as the design of porous media heat exchangers and porous media purifiers. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of a flow chart of a method for predicting pressure drop of a layered porous structure along a heat source direction according to the present invention;

[0037] Figure 2 Schematic diagram of the structure of the layered porous structure model in Example 1 of the present invention;

[0038] Figure 3 is the actual flow rate of each layer of the porous structure with a single porosity in Example 2 of the present invention;

[0039] Figure 4 is the actual inlet fluid velocity of each layer of the single porosity porous structure in Example 2 of the present invention;

[0040] Figure 5 This is a comparison chart of the predicted pressure drop and the actual simulated pressure drop in Example 2 of the present invention;

[0041] Figure 6 This is a comparison chart of the predicted pressure drop and the actual simulated pressure drop in Example 3 of the present invention;

[0042] Figure 7 This is a comparison chart of the predicted pressure drop and the actual simulated pressure drop in Example 4 of the present invention;

[0043] Figure 8 This is a comparison chart of the predicted pressure drop and the actual simulated pressure drop in Example 5 of the present invention. DETAILED DESCRIPTION

[0044] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0045] Example 1: This example provides a method for predicting the pressure drop of a layered porous structure along the direction of the heat source. Figure 1 As shown, the following steps are included:

[0046] S1. Establishing physical models of porous structures of different single porosity specifications, respectively, calculating the pressure drop of each porous structure of the single porosity at different inlet fluid velocities, and establishing a model between the inlet fluid velocity and pressure drop of the porous structure of the single porosity;

[0047] As a preferred embodiment of the present invention, specifically, the pressure drop of each porous structure with a single porosity at different inlet fluid velocities can be obtained through experiments, simulations, literature data or theoretical formulas. The porous structure with a single porosity is selected from one of a Weaire-Phelan lattice structure, a Kelvin lattice structure and a BCC lattice structure. The porosity range of the porous structure with a single porosity is 0.7 to 0.95. The correlation between the inlet fluid velocity and the pressure drop of the porous structure with a single porosity can be fitted into a quadratic function curve with a constant term of 0, as shown in formula (1):

[0048] (1)

[0049] in, is the pressure drop per unit length, represents the inlet fluid velocity, represents a linear constant, Represents the quadratic constant. Different single porosity porous structures correspond to different a and b, which can be obtained based on the actual fitting curve.

[0050] S2. Constructing a hierarchical porous structure model, confirming the total flow rate of the inlet fluid flowing into the hierarchical porous structure model, and confirming the actual flow rate of each layer of the hierarchical porous structure model with a single porosity;

[0051] As a preferred embodiment of this invention, specifically, Figure 2 As shown, the layered porous structure model is formed by stacking single-porosity porous structures of different porosities along the direction of the heat source, and the connecting rods of the two layers of single-porosity porous structures are stepped transitions or smooth transitions;

[0052] The total flow rate of the inlet fluid flowing into the hierarchical porous structure model is shown in formula (2):

[0053] (2)

[0054] in, represents the total inlet fluid flow of the layered porous structure model, represents the fluid density, represents the inlet fluid velocity, Indicates the fluid inlet cross-sectional area;

[0055] The actual flow rate of each layer of the single porosity porous structure in the hierarchical porous structure model is shown in formula (3) and formula (4):

[0056] (3)

[0057] (4)

[0058] in, represents the total inlet fluid flow of the layered porous structure model, represents the actual flow rate entering the first layer of the single porosity porous structure, represents the actual flow rate entering the second layer of the single porosity porous structure, represents the pressure drop of the first layer of a single porosity porous structure, Represents the pressure drop of the second layer of the single porosity porous structure.

[0059] S3. Determine the actual inlet fluid velocity of each layer of the single-porosity porous structure based on the actual flow rate of each layer of the single-porosity porous structure obtained in step S2, and determine the actual pressure drop of each layer of the single-porosity porous structure in the layered porous structure model based on the model between the inlet fluid velocity and pressure drop of the single-porosity porous structure obtained in step S1;

[0060] As a preferred embodiment of the present invention, specifically, the actual inlet fluid velocity of each layer of the porous structure with a single porosity obtained in step S2 is obtained as shown in formulas (5) and (6):

[0061] (5)

[0062] (6)

[0063] in, represents the actual inlet fluid velocity of the first layer of the single porosity porous structure, represents the actual flow rate entering the first layer of the single porosity porous structure, represents the total inlet fluid flow of the layered porous structure model, represents the inlet fluid velocity, represents the actual inlet fluid velocity of the second layer of the single porosity porous structure, represents the actual flow rate entering the second layer of the single porosity porous structure;

[0064] The pressure drop of each layer of the single porosity porous structure in the layered porous structure model is shown in formula (7) and formula (8):

[0065] (7)

[0066] (8)

[0067] in, represents the actual pressure drop of the first layer of the porous structure with a single porosity, The linear constant representing the first layer of the porous structure with a single porosity, represents the actual inlet fluid velocity of the first layer of the single porosity porous structure, represents the quadratic constant of the first layer of single porosity porous structure, represents the actual pressure drop of the second layer of the single porosity porous structure, represents the linear constant of the second layer single porosity porous structure, represents the actual inlet fluid velocity of the second layer of the single porosity porous structure, The quadratic constant representing the second layer of the single porosity porous structure.

[0068] S4. Taking the average of the actual pressure drop of each layer of the porous structure with a single porosity obtained in step S3, the pressure drop of the layered gradient porous structure along the heat source direction is obtained;

[0069] As a preferred embodiment of this invention, specifically, the pressure drop of the layered gradient porous structure along the heat source direction is as shown in formula (9):

[0070] (9)

[0071] in, represents the pressure drop of the layered gradient porous structure along the heat source direction, represents the actual pressure drop of the first layer of the porous structure with a single porosity, It represents the actual pressure drop of the second layer of the single porosity porous structure.

[0072] Example 2. This example provides a method for predicting the pressure drop of a layered porous structure along the direction of the heat source. The method in Example 1 is used, and the difference from the method mentioned in Example 1 is that the physical models of single-porosity porous structures of different specifications established in this example are: Weaire-Phelan lattice structure single-porosity porous structures with porosities of 0.75 and 0.95, respectively, and the cell size is 5 mm. The pressure drop of each single-porosity porous structure in the inlet fluid velocity range of 10-25 m / s is calculated by simulation. The layered porous structure model includes a stacked single-porosity porous structure with a Weaire-Phelan lattice structure of 0.75 porosity and a single-porosity porous structure with a Weaire-Phelan lattice structure of 0.95 porosity. The length of the layered porous structure model along the heat source direction is 10 mm, and the two layers each account for 50%. The actual flow rate of each layer of single-porosity porous structure in this example is as follows: Figure 3 In this embodiment, the relationship between the actual inlet fluid velocity and the theoretical inlet fluid velocity of each layer of the single porosity porous structure is as follows: Figure 4 shown.

[0073] In this embodiment, a real layered model was also established, including a Weaire-Phelan lattice structure with a single porosity porous structure of 0.75 and a Weaire-Phelan lattice structure with a single porosity porous structure of 0.95. The layered porous structure model was 10 mm long along the heat source direction, with each layer accounting for 50%. Fluent software was used to simulate the pressure drop. In this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop was 1.1%. Figure 5 shown.

[0074] Example 3. This example provides a method for predicting the pressure drop of a layered porous structure along the direction of a heat source. The method in Example 1 is used, but the difference from the method mentioned in Example 1 is that the physical models of single-porosity porous structures of different specifications established in this example are: Weaire-Phelan lattice structure single-porosity porous structures with porosities of 0.8 and 0.9, respectively, and the cell size is 5 mm. The pressure drop of each single-porosity porous structure is calculated by simulation when the inlet fluid velocity is in the range of 10-25 m / s. The layered porous structure model includes a stacked Weaire-Phelan lattice structure single-porosity porous structure with a porosity of 0.8 and a Weaire-Phelan lattice structure single-porosity porous structure with a porosity of 0.9. The length of the layered porous structure model along the direction of the heat source is 10 mm, and the two layers each account for 50%.

[0075] In this embodiment, a real layered model was also established, including a Weaire-Phelan lattice structure with a single porosity porous structure of 0.8 and a Weaire-Phelan lattice structure with a single porosity porous structure of 0.9. The layered porous structure model was 10 mm long along the heat source direction, with each layer accounting for 50%. Fluent software was used to simulate the pressure drop. In this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop was 0.9%. Figure 6 shown.

[0076] Example 4. This example provides a method for predicting the pressure drop of a layered porous structure along the direction of a heat source. The method in Example 1 is used, but the difference from the method mentioned in Example 1 is that the physical models of single-porosity porous structures of different specifications established in this example are: Weaire-Phelan lattice structures with porosities of 0.75 and 0.95, respectively, and the cell size is 5 mm. The pressure drop of each of the single-porosity porous structures is calculated by simulation when the inlet fluid velocity is in the range of 10-25 m / s. The layered porous structure model includes a stacked Weaire-Phelan lattice structure single-porosity porous structure with a porosity of 0.75 and a Weaire-Phelan lattice structure single-porosity porous structure with a porosity of 0.95. The length of the layered porous structure model along the direction of the heat source is 20 mm, and the two layers each account for 50%.

[0077] In this embodiment, a real layered model was also established, including a Weaire-Phelan lattice structure with a single porosity porous structure of 0.75 and a Weaire-Phelan lattice structure with a single porosity porous structure of 0.95. The layered porous structure model was 20 mm long along the heat source direction, with each layer accounting for 50%. Fluent software was used to simulate the pressure drop. In this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop was 1.45%. Figure 7 shown.

[0078] Example 5. This example provides a method for predicting the pressure drop of a layered porous structure along a heat source. The method used in Example 1 is employed, differing from that in that the physical models established for the single-porosity porous structures of different specifications in this example are: Weaire-Phelan lattice structures with porosities of 0.75 and 0.95, respectively, and a cell size of 5 mm. The pressure drop of each single-porosity porous structure is calculated through simulation for an inlet fluid velocity range of 10-25 m / s. The layered porous structure model includes stacked Weaire-Phelan lattice structure single porosity porous structures with a porosity of 0.75 and Weaire-Phelan lattice structure single porosity porous structures with a porosity of 0.95. The length of the layered porous structure model along the heat source direction is 20 mm, and the Weaire-Phelan lattice structure single porosity porous structures with a porosity of 0.75 account for 75%, and the Weaire-Phelan lattice structure single porosity porous structures with a porosity of 0.95 account for 25%.

[0079] This embodiment also establishes a real layered model, including a Weaire-Phelan lattice structure with a single porosity porous structure of 0.75 and a Weaire-Phelan lattice structure with a single porosity porous structure of 0.95. The length of the layered porous structure model along the heat source direction is 20 mm, the Weaire-Phelan lattice structure with a single porosity porous structure of 0.75 accounts for 75%, and the Weaire-Phelan lattice structure with a single porosity porous structure of 0.95 accounts for 25%. Fluent software is used to simulate and obtain the pressure drop. In this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop is 1.45%. Figure 8 shown.

[0080] The embodiments of the present invention are presented for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as suited for specific applications.

Claims

1. A method for predicting the pressure drop of a layered porous structure along the direction of a heat source, characterized in that: The steps include: S1. Establishing physical models of porous structures of different single porosity specifications, respectively, calculating the pressure drop of each porous structure of the single porosity at different inlet fluid velocities, and establishing a model between the inlet fluid velocity and pressure drop of the porous structure of the single porosity; S2. Constructing a hierarchical porous structure model, confirming the total flow rate of the inlet fluid flowing into the hierarchical porous structure model, and confirming the actual flow rate of each layer of the hierarchical porous structure model with a single porosity; S3. Determine the actual inlet fluid velocity of each layer of the single-porosity porous structure based on the actual flow rate of each layer of the single-porosity porous structure obtained in step S2, and determine the actual pressure drop of each layer of the single-porosity porous structure in the layered porous structure model based on the model between the inlet fluid velocity and pressure drop of the single-porosity porous structure obtained in step S1; S4. Taking the average of the actual pressure drop of each layer of the porous structure with a single porosity obtained in step S3, the pressure drop of the layered gradient porous structure along the heat source direction is obtained; In step S2, the actual flow rate of each layer of the single porosity porous structure in the layered porous structure model is shown in formula (1) and formula (2): （1） （2） in, represents the total inlet fluid flow of the layered porous structure model, represents the actual flow rate entering the first layer of the single porosity porous structure, represents the actual flow rate entering the second layer of the single porosity porous structure, represents the pressure drop of the first layer of a single porosity porous structure, represents the pressure drop of the second layer of the single porosity porous structure; The layered porous structure model is formed by stacking single-porosity porous structures with different porosities along the direction of the heat source.

2. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In the step S1, the single porosity porous structure is selected from one of a Weaire-Phelan lattice structure, a Kelvin lattice structure and a BCC lattice structure.

3. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In the step S1, the porosity of the single-porosity porous structure ranges from 0.7 to 0.

95.

4. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In step S1, the model between the inlet fluid velocity and pressure drop of the single porosity porous structure is shown in formula (3): （3） in, It represents the pressure drop per unit length, represents the inlet fluid velocity, represents a linear constant, represents the quadratic constant.

5. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In step S2, there is a step transition or a smooth transition between the connecting rods of the two layers of the porous structure with a single porosity.

6. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In step S2, the total flow rate of the inlet fluid flowing into the hierarchical porous structure model is as shown in formula (4): （4） in, represents the total inlet fluid flow of the layered porous structure model, represents the fluid density, represents the inlet fluid velocity, Indicates the fluid inlet cross-sectional area.

7. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In step S3, the actual inlet fluid velocity of each layer of the single-porosity porous structure obtained in step S2 is obtained according to the actual flow rate of each layer of the single-porosity porous structure as shown in formulas (5) and (6): （5） （6） in, represents the actual inlet fluid velocity of the first layer of the single porosity porous structure, represents the actual flow rate entering the first layer of the single porosity porous structure, represents the total inlet fluid flow of the layered porous structure model, represents the inlet fluid velocity, represents the actual inlet fluid velocity of the second layer of the single porosity porous structure, Represents the actual flow rate entering the second layer of single porosity porous structure.

8. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In step S3, the pressure drop of each layer of the single porosity porous structure in the layered porous structure model is shown in formula (7) and formula (8): （7） （8） in, represents the actual pressure drop of the first layer of the porous structure with a single porosity, The linear constant representing the first layer of the porous structure with a single porosity, represents the actual inlet fluid velocity of the first layer of the single porosity porous structure, represents the quadratic constant of the first layer of single porosity porous structure, represents the actual pressure drop of the second layer of the single porosity porous structure, represents the linear constant of the second layer single porosity porous structure, represents the actual inlet fluid velocity of the second layer of the single porosity porous structure, The quadratic constant representing the second layer of the single porosity porous structure.

9. The method for predicting the pressure drop of a layered porous structure along the heat source direction according to claim 1, characterized in that: In step S4, the pressure drop of the layered gradient porous structure along the heat source direction is shown in formula (9): （9） in, represents the pressure drop of the layered gradient porous structure along the heat source direction, represents the actual pressure drop of the first layer of the porous structure with a single porosity, It represents the actual pressure drop of the second layer of the single porosity porous structure.

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