A method for predicting the pressure drop of a continuous gradient porous structure along the flow direction

Abstract

The present invention belongs to the technical field of porous structure heat exchangers, and provides a method for predicting the pressure drop of a continuous gradient porous structure along the flow direction, including calculating the pressure drop of each single porosity porous structure at different inlet fluid velocities, establishing a correlation between the inlet fluid velocity and the pressure drop of the single porosity porous structure; calculating the inertial coefficient and the permeability coefficient of each single porosity porous structure; plotting the inertial coefficient - porosity diagram and the permeability coefficient - porosity diagram and performing linear fitting to obtain the inertial coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve; calculating the average inertial coefficient and the average permeability coefficient; constructing a continuous gradient porous structure model, inputting the average inertial coefficient and the average permeability coefficient into the continuous gradient porous structure model to obtain a continuous gradient porous structure prediction model, and predicting the pressure drop of the continuous gradient porous structure. The present invention can reduce the experimental and simulation costs and has a faster prediction speed.

Description

Technical Field

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

[0002] The pressure drop is a very important index in the design of porous structure heat exchangers, which involves key issues such as energy consumption in the heat exchange system used. The porous structure in the porous structure heat exchanger includes a uniform porous structure and a non-uniform porous structure. Currently, the pressure drop prediction models for the uniform porous structure include the Ergun equation, the Darcy equation, and the Darcy-Forchheimer equation, etc. In recent years, the research on the non-uniform porous structure has become a hot topic, and someone has invented a modeling method for the continuous gradient structure. For example, Patent CN117906417A discloses a porous medium heat exchanger based on a lattice unit structure with a gradient skeleton diameter. However, there are few reports on the method for predicting the pressure drop of a continuous gradient porous structure along the flow direction. Currently, most of the pressure drop data predictions for the continuous gradient porous structure can only be obtained through experimental or simulation methods, and it is impossible to quickly and accurately predict the pressure drop of the continuous gradient porous structure along the flow direction. Moreover, the experimental method requires 3D printing, which greatly increases the cost, and the quality of 3D printing varies, making it impossible to accurately obtain the pressure drop value. In view of the above existing problems, it is very necessary to research and design a new method for predicting the pressure drop of a continuous gradient porous structure along the flow direction to overcome the problems existing in the pressure drop prediction of the existing continuous gradient porous structure. Summary of the Invention

[0003] In order to solve the problems existing in the pressure drop prediction of the existing continuous gradient porous structure, such as complex prediction method and inability to quickly and accurately predict, the present invention proposes a method for predicting the pressure drop of a continuous gradient porous structure along the flow direction.

[0004] The present invention provides a method for predicting the pressure drop of a continuous gradient porous structure along the flow direction, including the following steps:

[0005] S1. Physically model porous structures with different specifications of single porosity respectively, calculate the pressure drop of each of the single-porosity porous structures at different inlet fluid velocities respectively, and establish a correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure;

[0006] S2. According to the correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure obtained in step S1, calculate the inertial coefficient and the permeability coefficient of each of the single-porosity porous structures respectively;

[0007] S3. Based on the inertia coefficient and permeability coefficient obtained in step S2, draw an inertia coefficient - porosity graph and a permeability coefficient - porosity graph respectively. After the drawing is completed, linearly fit the data in the inertia coefficient - porosity graph and the permeability coefficient - porosity graph respectively to obtain an inertia coefficient - porosity fitting curve and a permeability coefficient - porosity fitting curve;

[0008] S4. According to the inertia coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve obtained in step S3, calculate the average inertia coefficient and the average permeability coefficient of all the single - porosity porous structures established in step S1;

[0009] S5. Construct a continuous - gradient porous structure model, input the average inertia coefficient and the average permeability coefficient obtained in step S4 into the continuous - gradient porous structure model to obtain a continuous - gradient porous structure prediction model, and predict the pressure drop of the continuous - gradient porous structure through the continuous - gradient porous structure prediction model.

[0010] According to a method for predicting the pressure drop of a continuous - gradient porous structure along the flow direction according to some embodiments of the present application, in step S1, the single - porosity porous structure is selected from one of the Weaire - Phelan lattice structure, the Kelvin lattice structure, and the BCC lattice structure.

[0011] According to a method for predicting the pressure drop of a continuous - gradient porous structure along the flow direction according to some embodiments of the present application, in step S1, the porosity range of the single - porosity porous structure is: 0.7~0.95.

[0012] According to a method for predicting the pressure drop of a continuous - gradient porous structure along the flow direction according to some embodiments of the present application, in step S1, the correlation formula between the inlet fluid velocity and the pressure drop of the single - porosity porous structure is as shown in formula (1):

[0013] (1)

[0014] Wherein, represents the pressure drop per unit length, represents the dynamic viscosity of the fluid, represents the permeability coefficient, represents the inlet fluid velocity, represents the density of the fluid, represents the inertia coefficient.

[0015] A method for predicting pressure drop of a continuous gradient porous structure along the flow direction according to some embodiments of the present application. In step S2, calculating the inertial coefficient and permeability coefficient of each of the single-porosity porous structures includes plotting the pressure drop and inlet fluid velocity data of each specification of the single-porosity porous structure in a pressure-drop vs. velocity diagram, fitting the data in the pressure-drop vs. velocity diagram, respectively obtaining the pressure-drop vs. velocity curves of each specification of the single-porosity porous structure, and interpreting the first-order coefficient and second-order coefficient of each of the pressure-drop vs. velocity curves through the correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure to obtain the inertial coefficient and permeability coefficient of the single-porosity porous structure.

[0016] A method for predicting pressure drop of a continuous gradient porous structure along the flow direction according to some embodiments of the present application. In step S3, the coefficient of determination of the linear fitting is greater than 0.999.

[0017] A method for predicting pressure drop of a continuous gradient porous structure along the flow direction according to some embodiments of the present application. In step S4, the average permeability coefficient of the single-porosity porous structure is as shown in formula (2):

[0018] (2)

[0019] Wherein, represents the average permeability coefficient, represents the porosity at the end along the flow direction, represents the porosity at the start along the flow direction, represents the permeability coefficient, represents the functional expression of the permeability coefficient-porosity fitting curve.

[0020] A method for predicting pressure drop of a continuous gradient porous structure along the flow direction according to some embodiments of the present application. In step S4, the average inertial coefficient of the single-porosity porous structure is as shown in formula (3):

[0021] (3)

[0022] Wherein, represents the average inertial coefficient, represents the porosity at the end along the flow direction, represents the porosity at the start along the flow direction, represents the inertial coefficient, represents the functional expression of the inertial coefficient-porosity fitting curve.

[0023] A method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to some embodiments of the present application. In step S5, the porosity of the continuous gradient porous structure varies continuously according to a linear function along the flow direction.

[0024] A method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to some embodiments of the present application. In step S5, the prediction model of the continuous gradient porous structure is shown in formula (4):

[0025] (4)

[0026] Where, represents the predicted pressure drop per unit length, represents the dynamic viscosity of the fluid, represents the average permeability coefficient, represents the inlet fluid velocity, represents the density of the fluid, represents the average inertia coefficient.

[0027] A method for predicting the pressure drop of a continuous gradient porous structure along the flow direction proposed by the present invention can obtain the pressure drop parameters of the continuous gradient porous structure without other simulation or experimental means under the condition of determining the pressure drop parameters of the single-porosity porous structure, and can obtain the pressure drop in any gradient range. The present invention also proves that for a continuous gradient structure, as long as the average inertia coefficient and average permeability coefficient of its variable characteristic parameters in the interval are determined, the macroscopic characteristics of the continuous gradient structure can be obtained, providing an idea for research other than the flow resistance characteristics of the continuous gradient structure. And the pressure drop prediction data obtained by the prediction method of the present invention is accurate, has great application potential, and can effectively guide the design of porous structure flow components, such as the design of porous medium heat exchangers and porous medium cold plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic flow chart of a method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to the present invention;

[0029] Figure 2 is a schematic structural diagram of a continuous gradient porous structure in Embodiment 1 of the present invention;

[0030] Figure 3 is a schematic diagram of the pressure drop - velocity curve of a single-porosity porous structure of each specification fitted in Embodiment 2 of the present invention;

[0031] Figure 4 is a schematic diagram of the inertia coefficient - porosity fitting curve of a single-porosity porous structure of each specification fitted in Embodiment 2 of the present invention;

[0032] Figure 5Schematic diagram of the permeability coefficient - porosity fitting curve of the single - porosity porous structure of each specification fitted in Embodiment 2 of the present invention;

[0033] Figure 6 Comparison diagram of the predicted pressure drop and the actual simulated pressure drop of the first continuous - gradient porous - structure model in Embodiment 2 of the present invention;

[0034] Figure 7 Comparison diagram of the predicted pressure drop and the actual simulated pressure drop of the second continuous - gradient porous - structure model in Embodiment 2 of the present invention;

[0035] Figure 8 Comparison diagram of the predicted pressure drop and the actual simulated pressure drop of the third continuous - gradient porous - structure model in Embodiment 2 of the present invention;

[0036] Figure 9 Comparison diagram of the predicted pressure drop and the actual simulated pressure drop of the fourth continuous - gradient porous - structure model in Embodiment 2 of the present invention. Detailed implementation manners

[0037] The following further describes in detail the implementation manners of the present invention in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0038] Embodiment 1. This embodiment provides a method for predicting the pressure drop of a continuous - gradient porous structure along the flow direction, as Figure 1 shown, including the following steps:

[0039] S1. Physically model single - porosity porous structures of different specifications respectively, calculate the pressure drops of each single - porosity porous structure at different inlet fluid velocities respectively, and establish the correlation expressions between the inlet fluid velocity and the pressure drop of each single - porosity porous structure respectively;

[0040] As a preference of this embodiment, specifically, the pressure drops of each single - porosity porous structure at different inlet fluid velocities can be obtained through experiments, simulations, literature data or theoretical formulas. The single - porosity porous structure is selected from one of the Weaire - Phelan lattice structure, Kelvin lattice structure and BCC lattice structure; the porosity range of the single - porosity porous structure is: 0.7 - 0.95; the form of the correlation expression between the inlet fluid velocity and the pressure drop of the single - porosity porous structure is a quadratic function with a constant term of 0, as shown in formula (1):

[0041] (1)

[0042] Among them, represents the pressure drop per unit length, represents the dynamic viscosity of the fluid, represents the permeability coefficient, represents the inlet fluid velocity, represents the density of the fluid, represents the inertia coefficient.

[0043] S2. According to the correlation formula between the inlet fluid velocity and the pressure drop of each single-porosity porous structure obtained in step S1, the inertia coefficient and the permeability coefficient of each single-porosity porous structure are obtained respectively;

[0044] As a preference of this embodiment, specifically, calculating the inertia coefficient and the permeability coefficient of each single-porosity porous structure includes plotting the pressure drop and inlet fluid velocity data of each specification of the single-porosity porous structure in a pressure-drop - velocity diagram, fitting the data in the pressure-drop - velocity diagram, respectively obtaining the pressure-drop - velocity curves of each specification of the single-porosity porous structure, and interpreting the first-order coefficient and the second-order coefficient of each pressure-drop - velocity curve through the correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure to obtain the inertia coefficient and the permeability coefficient of the single-porosity porous structure. As can be seen from formula (1), the dynamic viscosity of the fluid is known, and the permeability coefficient can be obtained through the first-order coefficient of the correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure , the density of the fluid is known, and the inertia coefficient can be obtained through the second-order coefficient of the correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure .

[0045] S3. According to the inertia coefficient and the permeability coefficient obtained in step S2, an inertia coefficient - porosity diagram and a permeability coefficient - porosity diagram are respectively plotted. After the plotting is completed, the data in the inertia coefficient - porosity diagram and the permeability coefficient - porosity diagram are respectively linearly fitted to obtain an inertia coefficient - porosity fitting curve and a permeability coefficient - porosity fitting curve;

[0046] As a preference of this embodiment, specifically, the coefficient of determination of the linear fitting is greater than 0.999.

[0047] S4. According to the inertia coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve obtained in step S3, the average inertia coefficient and the average permeability coefficient of all specifications of the single-porosity porous structures established in step S1 are calculated;

[0048] As a preference of this embodiment, specifically, the average permeability coefficient of the single-porosity porous structure is as shown in formula (2):

[0049] (2)

[0050] Wherein, represents the average permeability coefficient, represents the porosity at the end along the flow direction, represents the initial porosity along the flow direction, represents the permeability coefficient, represents the functional expression of the permeability coefficient - porosity fitting curve;

[0051] The average inertia coefficient of a single - porosity porous structure is as shown in formula (3):

[0052] (3)

[0053] wherein, represents the average inertia coefficient, represents the porosity at the end along the flow direction, represents the initial porosity along the flow direction, represents the inertia coefficient, represents the functional expression of the inertia coefficient - porosity fitting curve.

[0054] S5. Construct a continuous - gradient porous - structure model, input the average inertia coefficient and average permeability coefficient obtained in step S4 into the continuous - gradient porous - structure model to obtain a continuous - gradient porous - structure prediction model, and predict the pressure drop of the continuous - gradient porous structure through the continuous - gradient porous - structure prediction model;

[0055] As a preference of this embodiment, specifically, as Figure 2 shown, the porosity of the continuous - gradient porous structure varies continuously according to a linear function along the flow direction;

[0056] The continuous - gradient porous - structure prediction model is as shown in formula (4):

[0057] (4)

[0058] wherein, represents the predicted pressure drop per unit length, represents the dynamic viscosity of the fluid, represents the average permeability coefficient, represents the inlet fluid velocity, represents the density of the fluid, represents the average inertia coefficient.

[0059] Embodiment 2. This embodiment provides a method for predicting the pressure drop of a continuous - gradient porous structure along the flow direction, including the following steps:

[0060] Physical models of single-porosity porous structures with different specifications were established respectively. The cell size was 5 mm for all, and the porosities were 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95 respectively. The ANSYS Fluent software was used to perform simulations to calculate the pressure drops of each single-porosity porous structure in the inlet fluid velocity range of 10 - 25 m / s, and a correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure was established, such as formula (1) in Example 1. The pressure drop and inlet fluid velocity data of each specification of the single-porosity porous structure were plotted in a pressure drop - velocity diagram, and the data in the pressure drop - velocity diagram were fitted. As Figure 3 shown, the pressure drop - velocity curves of each specification of the single-porosity porous structure were obtained respectively. By interpreting the first-order coefficient and the second-order coefficient of each pressure drop - velocity curve through the correlation formula between the inlet fluid velocity and the pressure drop of the single-porosity porous structure, the inertial coefficient and the permeability coefficient of the single-porosity porous structure were obtained.

[0061] According to the inertial coefficient and the permeability coefficient obtained in step S2, an inertial coefficient - porosity diagram and a permeability coefficient - porosity diagram were plotted respectively. After plotting, the data in the inertial coefficient - porosity diagram and the permeability coefficient - porosity diagram were linearly fitted respectively. The fitting determination coefficient of the linear fitting was greater than 0.999, and an inertial coefficient - porosity fitting curve and a permeability coefficient - porosity fitting curve were obtained. The inertial coefficient - porosity fitting curve was as Figure 4 shown, and the permeability coefficient - porosity fitting curve was as Figure 5 shown. The average inertial coefficient and the average permeability coefficient of all specifications of the single-porosity porous structure were calculated through formula (2) and formula (3) in Example 1.

[0062] In this embodiment, four continuous gradient porous structure models were constructed. The gradient porosity ranges of the four continuous gradient porous structure models were: 0.8 - 0.9, 0.75 - 0.95, 0.7 - 0.9, and 0.85 - 0.95.

[0063] The first continuous gradient porous structure model: The initial porosity along the flow direction was 0.9, the final porosity along the flow direction was 0.8, and the porosity gradient along the flow direction changed uniformly. The average inertial coefficient and the average permeability coefficient were obtained by averaging the inertial coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve in the porosity range of 0.8 - 0.9 respectively. And the obtained average inertial coefficient and average permeability coefficient were substituted into formula (4) of the continuous gradient porous structure prediction model in Example 1 to obtain the predicted pressure drops at different inlet fluid velocities. In addition, in this implementation, a three-dimensional gradient model of a continuous gradient porous structure with an actual gradient porosity range of 0.8 - 0.9 was established and simulated to obtain pressure drop data. As Figure 6As shown, in this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop is 1.8%.

[0064] The second continuous gradient porous structure model: The initial porosity along the flow direction is 0.95, the final porosity along the flow direction is 0.75, and the porosity gradient along the flow direction changes uniformly. The average inertia coefficient and the average permeability coefficient are obtained by averaging the inertia coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve in the porosity range of 0.75 - 0.95, respectively. Then, the obtained average inertia coefficient and average permeability coefficient are substituted into formula (4) of the continuous gradient porous structure prediction model in Example 1 to obtain the predicted pressure drops at different inlet fluid velocities. In addition, in this implementation, a three-dimensional gradient model of a continuous gradient porous structure with an actual gradient porosity range of 0.75 - 0.95 is established and simulated to obtain pressure drop data. As Figure 7 shown, in this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop is 3.0%.

[0065] The third continuous gradient porous structure model: The initial porosity along the flow direction is 0.9, the final porosity along the flow direction is 0.7, and the porosity gradient along the flow direction changes uniformly. The average inertia coefficient and the average permeability coefficient are obtained by averaging the inertia coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve in the porosity range of 0.7 - 0.9, respectively. Then, the obtained average inertia coefficient and average permeability coefficient are substituted into formula (4) of the continuous gradient porous structure prediction model in Example 1 to obtain the predicted pressure drops at different inlet fluid velocities. In addition, in this implementation, a three-dimensional gradient model of a continuous gradient porous structure with an actual gradient porosity range of 0.7 - 0.9 is established and simulated to obtain pressure drop data. As Figure 8 shown, in this embodiment, the maximum error between the predicted pressure drop and the actual simulated pressure drop is 1.7%.

[0066] The fourth continuous gradient porous structure model: The initial porosity along the flow direction is 0.95, the final porosity along the flow direction is 0.85, and the porosity gradient along the flow direction changes uniformly. The average inertia coefficient and the average permeability coefficient are obtained by averaging the inertia coefficient - porosity fitting curve and the permeability coefficient - porosity fitting curve in the porosity range of 0.85 - 0.95, respectively. Then, the obtained average inertia coefficient and average permeability coefficient are substituted into formula (4) of the continuous gradient porous structure prediction model in Example 1 to obtain the predicted pressure drops at different inlet fluid velocities. In addition, in this implementation, a three-dimensional gradient model of a continuous gradient porous structure with an actual gradient porosity range of 0.85 - 0.95 is established and simulated to obtain pressure drop data. As Figure 9 shown, in this embodiment, the maximum error between the predicted pressure drop value and the actual simulated pressure drop value is 1.4%.

[0067] The embodiments of the present invention are given for purposes of illustration and description, and are not exhaustive or limit the invention to the disclosed forms. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are chosen and described in order to best explain the principles of the invention and its practical application, and to enable those of ordinary skill in the art to understand the invention so as to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for predicting the pressure drop of a continuous gradient porous structure along the flow direction, characterized in that: The steps include: S1. 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 correlation between the inlet fluid velocity and the pressure drop of the single porosity porous structure; S2. calculating the inertia coefficient and permeability coefficient of each single porosity porous structure according to the correlation between the inlet fluid velocity and the pressure drop of the single porosity porous structure obtained in step S1; S3. According to the inertia coefficient and permeability coefficient obtained in step S2, a coefficient of inertia-porosity diagram and a permeability-porosity diagram are drawn respectively. After the drawing is completed, the data in the coefficient of inertia-porosity diagram and the permeability-porosity diagram are linearly fitted to obtain a coefficient of inertia-porosity fitting curve and a permeability-porosity fitting curve; S4. Calculate the average inertia coefficient and average permeability coefficient of the single porosity porous structure of all specifications established in step S1 according to the inertia coefficient-porosity fitting curve and permeability coefficient-porosity fitting curve obtained in step S3; S5. Construct a continuous gradient porous structure model, input the average inertia coefficient and average permeability coefficient obtained in step S4 into the continuous gradient porous structure model to obtain a continuous gradient porous structure prediction model, and predict the pressure drop of the continuous gradient porous structure by using the continuous gradient porous structure prediction model.

2. The method for predicting the pressure drop of a continuous gradient porous structure along the flow 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 continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In the step S1, the porosity range of the single porosity porous structure is: 0.7~0.

95.

4. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In step S1, the correlation between the inlet fluid velocity and the pressure drop of the single porosity porous structure is shown in formula (1): （1） in, is the pressure drop per unit length, represents the dynamic viscosity of the fluid, represents the permeability coefficient, is the inlet fluid velocity, represents the density of the fluid, represents the coefficient of inertia.

5. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 4, characterized in that: In step S2, the calculation of the coefficient of inertia and the coefficient of permeability of each single porosity porous structure includes plotting the pressure drop and inlet fluid velocity data of each specification of the single porosity porous structure in a pressure drop-velocity diagram, fitting the data in the pressure drop-velocity diagram to obtain the pressure drop-velocity curve of each specification of the single porosity porous structure, and interpreting the linear coefficient and the quadratic coefficient of each pressure drop-velocity curve through the correlation between the inlet fluid velocity and the pressure drop of the single porosity porous structure to obtain the coefficient of inertia and the permeability of the single porosity porous structure.

6. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In step S3, the fitting determination coefficient of the linear fitting is greater than 0.

999.

7. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In step S4, the average permeability coefficient of the single porosity porous structure is as shown in formula (2): （2） in, represents the average permeability coefficient, represents the end porosity along the flow direction, represents the initial porosity along the flow direction, represents the permeability coefficient, Function expression representing the permeability-porosity fitting curve.

8. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In step S4, the average inertia coefficient of the single porosity porous structure is as shown in formula (3): （3） in, represents the average inertia coefficient, represents the end porosity along the flow direction, represents the initial porosity along the flow direction, represents the inertia coefficient, Function expression representing the inertia coefficient-porosity fitting curve.

9. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In the step S5, the porosity of the continuous gradient porous structure along the flow direction changes continuously according to a linear function.

10. The method for predicting the pressure drop of a continuous gradient porous structure along the flow direction according to claim 1, characterized in that: In step S5, the continuous gradient porous structure prediction model is shown in formula (4): （4） in, represents the predicted pressure drop per unit length, represents the dynamic viscosity of the fluid, represents the average permeability coefficient, is the inlet fluid velocity, represents the density of the fluid, represents the mean inertia coefficient.

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