Analysis Method and Application of Flow Characteristics in Tank under the Action of Flexible Stirring Mechanism

Abstract

The present application relates to the field of biological fermentation technology, and discloses a method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism and its application. Among them, the method includes: constructing a fluid domain simulation module in the tank and a solid domain simulation module of the flexible stirring mechanism; generating a liquid phase acting force based on the fluid domain simulation module, and iterating the first boundary condition of the solid domain simulation module based on the liquid phase acting force; generating a deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating the second boundary condition of the fluid domain simulation module based on the deformation displacement; constructing a fluid-structure interaction model based on the fluid domain simulation module and the solid domain simulation module, and obtaining an analysis result of the flow characteristics based on the fluid-structure interaction model, solving the technical problem of how to accurately simulate the flow characteristics in the tank under the action of the flexible stirring mechanism.

Description

Technical Field

[0001] This application relates to the field of biological fermentation technology, and particularly to a method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism and its application. Background Art

[0002] Related fermentation methods can be divided into two types according to different action mechanisms: mechanical stirring fermentation method and pit composting fermentation method. The mechanical stirring fermentation method applies an external force to the fermentation broth, so better flow effects can be obtained. The strong shear force caused by the traditional rigid stirring mechanism during operation will lead to a significant reduction in biological activity, thereby affecting the ethanol yield. The flexible stirring mechanism is proposed to solve this problem and optimize the mass transfer effect. Among them, the blade material of the rigid stirring mechanism is a rigid material, which can maintain a stable shape and structure during stirring. The blade of the flexible stirring mechanism is a flexible blade, which has good flexibility and elasticity and will produce certain deformation during stirring. The deformation of the flexible blade can enhance the fluid disturbance and improve the mixing efficiency. However, the related simulation methods cannot accurately reflect the flow characteristics in the tank under the action of the flexible stirring mechanism. Summary of the Invention

[0003] This application provides a method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism and its application. It solves the technical problem of how to accurately simulate the flow characteristics in the tank under the action of the flexible stirring mechanism and achieves the technical effect of improving the simulation accuracy.

[0004] To achieve the above object, the main technical solutions adopted in this application include:

[0005] In a first aspect, an embodiment of this application provides a method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism. The method includes: constructing a fluid domain simulation module in the tank and a solid domain simulation module of the flexible stirring mechanism; generating a liquid-phase acting force based on the fluid domain simulation module, and iterating the first boundary condition of the solid domain simulation module based on the liquid-phase acting force; generating a deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating the second boundary condition of the fluid domain simulation module based on the deformation displacement; constructing a fluid-structure interaction model based on the fluid domain simulation module and the solid domain simulation module, and obtaining a flow characteristic analysis result based on the fluid-structure interaction model.

[0006] The method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism provided in this embodiment includes: constructing a fluid domain simulation module for the fluid in the tank and a solid domain simulation module for the flexible stirring mechanism; generating a liquid-phase acting force based on the fluid domain simulation module, and iterating the first boundary condition of the solid domain simulation module based on the liquid-phase acting force; generating a deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating the second boundary condition of the fluid domain simulation module based on the deformation displacement; constructing a fluid-structure interaction model based on the fluid domain simulation module and the solid domain simulation module, and obtaining an analysis result of the flow characteristics based on the fluid-structure interaction model, which solves the technical problem of how to accurately simulate the flow characteristics in the tank under the action of the flexible stirring mechanism.

[0007] Optionally, constructing the fluid domain simulation module for the fluid in the tank and the solid domain simulation module for the flexible stirring mechanism includes: obtaining the geometric model of the fluid domain in the tank and the geometric model of the solid domain of the flexible stirring mechanism; performing structured grid division on the geometric model of the fluid domain and the geometric model of the solid domain to obtain a fluid domain grid and a solid domain grid respectively; constructing the fluid domain simulation module based on the fluid domain grid; and constructing the solid domain simulation module based on the solid domain grid.

[0008] Optionally, the minimum orthogonal quality of the discrete elements in the fluid domain grid and the solid domain grid is greater than 0.35, the average orthogonal quality is greater than 0.9, the maximum skewness is less than 0.65, and the average skewness is less than 0.15; the relative distance between the fluid domain boundary grid nodes and the solid domain boundary is less than 1, where the solid domain boundary is determined by the geometric model of the solid domain.

[0009] Optionally, the relative distance between the fluid domain boundary grid nodes and the solid domain boundary is determined in the following manner: calculating the absolute distance between each fluid domain boundary grid node and the solid domain boundary; calculating the ratio of each absolute distance to the element length of the solid domain boundary; identifying the maximum ratio among the ratios, and taking the maximum ratio as the relative distance between the fluid domain boundary grid nodes and the solid domain boundary.

[0010] Optionally, the method further includes: obtaining a plurality of different grid numbers, where the maximum grid number is 3-4 times the minimum grid number; performing structured grid division on the geometric model of the fluid domain and the geometric model of the solid domain based on each grid number to obtain the corresponding fluid-structure interaction model; obtaining the corresponding turbulent kinetic energy distribution result of the fluid in the tank based on each fluid-structure interaction model; identifying the target distribution result that meets the preset standard among the turbulent kinetic energy distribution results, and determining the grid number corresponding to the target distribution result as the target grid number, and constructing a target fluid-structure interaction model according to the target grid number.

[0011] Optionally, the method further includes: obtaining an axial velocity simulation result of the fluid in the tank based on the target fluid-structure interaction model; if the error between the axial velocity simulation result and the corresponding axial velocity test result is less than a specified error, determining that the target fluid-structure interaction model meets the accuracy requirement.

[0012] Optionally, the specified error is set to 15%, and the data transmission rate between the fluid domain simulation module and the solid domain simulation module is greater than 95%.

[0013] Optionally, constructing the fluid domain simulation module in the tank includes: setting the fluid in the tank as a single-phase fluid; using the standard k-epsilon two-equation model to simulate the turbulent characteristics of the fluid in the tank; using the SIMPLE algorithm, pressure second-order format spatial discretization, and momentum second-order upwind format spatial discretization to perform simulation analysis on the fluid in the tank.

[0014] Optionally, the method further includes: combining tanks with different structures and stirring mechanisms of different types to obtain multiple different tank-stirring mechanism combinations; for each group of the tank-stirring mechanism combinations, generating corresponding flow characteristic analysis results based on the fluid-structure interaction model; determining a target tank-stirring mechanism combination based on each of the flow characteristic analysis results.

[0015] In a second aspect, an embodiment of the present application provides a method for designing a bioreactor, applying the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism described above.

[0016] In a third aspect, an embodiment of the present application provides a computer device, including: a memory and a processor, which are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to execute the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism described above.

[0017] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, on which computer instructions are stored, and the computer instructions are used to cause a computer to execute the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism described above.

[0018] In a fifth aspect, an embodiment of the present application provides a computer program product, including computer instructions, and the computer instructions are used to cause a computer to execute the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism described above. Description of the Drawings

[0019] To more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a flowchart of the analysis method for the flow characteristics in the tank under the action of the flexible stirring mechanism provided by the embodiment of the present application;

[0021] Figure 2 It is a schematic diagram of the fluid domain grid provided by the embodiment of the present application;

[0022] Figure 3 It is a schematic diagram of the solid domain grid provided by the embodiment of the present application;

[0023] Figure 4 It is a curve graph of the turbulent kinetic energy distribution of the first division scheme provided by the embodiment of the present application;

[0024] Figure 5 It is a curve graph of the turbulent kinetic energy distribution of the second division scheme provided by the embodiment of the present application;

[0025] Figure 6 It is a curve graph of the turbulent kinetic energy distribution of the third division scheme provided by the embodiment of the present application;

[0026] Figure 7 It is a curve graph of the turbulent kinetic energy distribution of the fourth division scheme provided by the embodiment of the present application;

[0027] Figure 8 It is a curve graph of the velocity distribution obtained from the simulation and test provided by the embodiment of the present application;

[0028] Figure 9 It is a cloud diagram of the velocity distribution in the tank of the rigid six-blade straight vane disk turbine impeller at a rotational speed of 150 r / min provided by the embodiment of the present application;

[0029] Figure 10 It is a cloud diagram of the velocity distribution in the tank of the flexible six-blade straight vane disk turbine impeller at a rotational speed of 150 r / min provided by the embodiment of the present application;

[0030] Figure 11 It is a cloud diagram of the velocity distribution in the tank of the rigid six-blade straight vane disk turbine impeller at a rotational speed of 300 r / min provided by the embodiment of the present application;

[0031] Figure 12 It is a cloud diagram of the velocity distribution in the tank of the flexible six-blade straight vane disk turbine impeller at a rotational speed of 300 r / min provided by the embodiment of the present application;

[0032] Figure 13 It is a comparison chart of the power consumption per unit product under different simulation conditions with a liquid phase viscosity of 15 mPa provided by the embodiments of the present application;

[0033] Figure 14 It is a comparison chart of the power consumption per unit product under different simulation conditions with a liquid phase viscosity of 50 mPa provided by the embodiments of the present application;

[0034] Figure 15 It is a schematic structural diagram of a computer device provided by the embodiments of the present application. Detailed implementation manners

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present application.

[0036] Under the global background of the greenhouse effect and environmental pollution, fuel ethanol has shown great application potential and market value in replacing traditional fossil fuels. Currently, fuel ethanol is usually anaerobically fermented by the biological method, and its fermentation broth raw materials mainly come from agricultural waste including straw, sugar beet, sorghum, and rotten fruits. The fermentation steps include raw material treatment, sugar hydrolysis, solid filtration, biological fermentation, and separation and purification. Among them, the fermentation effect is directly related to the utilization rate of raw materials and the yield of ethanol products. According to different action mechanisms, the related fermentation methods can be divided into two types: mechanical stirring fermentation method and pit composting fermentation method. The mechanical stirring fermentation method applies an external force to the fermentation broth, so a better flow effect can be obtained.

[0037] The fermentation tank in the mechanical stirring fermentation method includes a tank body and a stirring mechanism. The stirring mechanism includes a paddle and a stirring shaft. According to the different materials of the paddle, the fermentation tank is divided into a rigid fermentation tank and a flexible fermentation tank. The stirring mechanisms of the rigid fermentation tank and the flexible fermentation tank are a rigid stirring mechanism and a flexible stirring mechanism respectively. The paddle of the rigid stirring mechanism is made of a rigid material and can maintain a stable shape and structure during stirring. The paddle of the flexible stirring mechanism is a flexible paddle, which has good flexibility and elasticity and will produce a certain deformation during stirring. The deformation of the flexible paddle can enhance the disturbance of the fluid and improve the mixing efficiency. The strong shear force caused by the traditional rigid stirring mechanism during operation will cause a significant reduction in biological activity, thereby affecting the ethanol yield. The flexible stirring mechanism is proposed to solve this problem and optimize the mass transfer effect. However, the related simulation methods cannot accurately reflect the flow characteristics in the tank under the action of the flexible stirring mechanism.

[0038] An embodiment of the present application provides a method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0039] Please refer to Figure 1 , Figure 1 which is a flowchart of the method for analyzing the flow characteristics in a tank under the action of the flexible stirring mechanism provided by the embodiment of the present application. As Figure 1 shown, the process includes the following steps:

[0040] Step S1, construct a fluid domain simulation module in the tank and a solid domain simulation module of the flexible stirring mechanism.

[0041] Among them, there is fluid (which can be fermentation broth) in the tank. The fluid domain refers to the spatial region occupied by the fluid in the tank. The fluid domain simulation module is used to simulate or calculate physical quantities such as the flow characteristics, pressure distribution, and temperature change of the fluid in the tank. The solid domain refers to the spatial region occupied by the flexible stirring mechanism. The flexible stirring mechanism includes a stirring shaft, flexible blades, and a connecting component for connecting the two. The solid domain simulation module is used to simulate or calculate physical quantities such as the stress, strain, and deformation of the flexible stirring mechanism. There is an interaction between the fluid and the flexible stirring mechanism.

[0042] Step S3, based on the fluid domain simulation module, generate a liquid-phase acting force, and based on the liquid-phase acting force, iterate the first boundary condition of the solid domain simulation module.

[0043] Among them, the liquid-phase acting force refers to the acting force of the fluid in the tank on the boundary of the solid domain. Use the fluid domain simulation model to perform flow field calculations to obtain a solution set of flow field data. Extract the liquid-phase acting force from the solution set of flow field data, and iterate the first boundary condition (i.e., the mechanical boundary condition) of the solid domain simulation module based on the liquid-phase acting force to reflect the influence of the flow field on the deformation of the flexible blades.

[0044] Step S5, based on the solid domain simulation module, generate the deformation displacement of the flexible stirring mechanism, and based on the deformation displacement, iterate the second boundary condition of the fluid domain simulation module.

[0045] Among them, the liquid-phase acting force generated by the fluid will cause the flexible blades to deform and generate a deformation displacement. The deformation of the flexible blades will in turn affect the flow field. In the solid domain simulation module, calculate the deformation displacement of the flexible stirring mechanism under the action of the fluid. Based on the deformation displacement, iterate the second boundary condition of the fluid domain simulation module to reflect the influence of the deformation of the flexible blades on the fluid flow field.

[0046] Step S7: Based on the fluid domain simulation module and the solid domain simulation module, construct a fluid-structure interaction model, and based on the fluid-structure interaction model, obtain the analysis results of the flow characteristics.

[0047] Among them, the fluid-structure interaction model is used to simultaneously analyze how the fluid flow affects the deformation of the flexible stirring mechanism and how the deformation of the flexible stirring mechanism in turn affects the fluid flow. The analysis results of the flow characteristics include the velocity distribution, etc. By constructing the fluid-structure interaction model, an accurate simulation of the influence of the flexible stirring mechanism on the flow characteristics of the fluid in the tank is realized, which can be used to optimize the fermenter, including the design of the tank body and the flexible stirring mechanism, and improve the mass transfer effect.

[0048] For example, by setting the number of iterations and the step size, in each iteration, based on the first boundary condition of the iteration, the solid domain simulation module recalculates the deformation displacement of the blade, and based on the second boundary condition of the iteration, the fluid domain simulation module recalculates the flow field. Repeat steps S3 - S5 to achieve two-way fluid-structure interaction, and based on the converged fluid-structure interaction model, analyze the flow characteristics of the fluid in the tank.

[0049] The method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism provided in this embodiment includes: constructing a fluid domain simulation module for the fluid in the tank and a solid domain simulation module for the flexible stirring mechanism; generating a liquid phase acting force based on the fluid domain simulation module, and iterating the first boundary condition of the solid domain simulation module based on the liquid phase acting force; generating the deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating the second boundary condition of the fluid domain simulation module based on the deformation displacement; constructing a fluid-structure interaction model based on the fluid domain simulation module and the solid domain simulation module, and obtaining the analysis results of the flow characteristics based on the fluid-structure interaction model, which solves the technical problem of how to accurately simulate the flow characteristics in the tank under the action of the flexible stirring mechanism.

[0050] In some embodiments, constructing the fluid domain simulation module for the fluid in the tank and the solid domain simulation module for the flexible stirring mechanism includes: obtaining the geometric model of the fluid domain in the tank and the geometric model of the solid domain of the flexible stirring mechanism; performing structured grid division on the geometric model of the fluid domain and the geometric model of the solid domain to obtain a fluid domain grid and a solid domain grid respectively; constructing the fluid domain simulation module based on the fluid domain grid; and constructing the solid domain simulation module based on the solid domain grid.

[0051] Among them, structured grid generation includes two steps: regular division and structured discretization. Regularly dividing the fluid domain geometric model and the solid domain geometric model so that they are respectively composed of several geometric bodies with regular shapes is beneficial for subsequent structured discretization. Structurally discretizing the fluid domain geometric model and the solid domain geometric model after regular division respectively to form a structured fluid domain grid and a solid domain grid. Please refer to Figure 2 and Figure 3 , Figure 2 which is a schematic diagram of the fluid domain grid provided by the embodiment of the present application, Figure 3 and Figure 2 which is a schematic diagram of the solid domain grid provided by the embodiment of the present application. For example, for a six-straight-blade disk turbine rigid fermenter, its fluid domain grid is as shown in Figure 3 . The inner diameter of the tank body is 300 mm, the height of the liquid phase in the tank is 300 mm, and four groups of baffles with a width of 30 mm, a height of 300 mm, and a thickness of 4 mm are equipped on the inner wall surface of the tank; its solid domain grid is as shown in

[0052] . The corresponding stirring mechanism is a central shaft type six-straight-blade disk turbine impeller with a blade diameter of 130 mm. Structured grids are superior to unstructured grids in terms of computational efficiency and accuracy. Based on the fluid domain grid, a fluid domain simulation module is established to calculate the fluid flow characteristics. Based on the solid domain grid, a solid domain simulation module is established to calculate the deformation of the solid structure (flexible stirring mechanism). By performing structured grid generation on the fluid domain geometric model and the solid domain geometric model, the grids at the interface between the fluid domain and the solid domain are matched, which is beneficial for improving the computational efficiency and accuracy.

[0053] Among them, after regular division and structured discretization of the fluid domain and the solid domain, the minimum orthogonal quality of the discrete elements should be greater than 0.35, the average orthogonal quality should be greater than 0.9, the maximum skewness should be less than 0.65, and the average skewness should be less than 0.15 to ensure the grid quality of the fluid domain grid and the solid domain grid, which is beneficial for ensuring the simulation accuracy. Set the relative distance between the fluid domain boundary grid nodes in the fluid domain grid and the solid domain boundary to be less than 1, so that the fluid domain and the solid domain have a good matching degree at the fluid-structure interaction interface.

[0054] In some embodiments, the relative distance between the fluid domain boundary grid nodes and the solid domain boundary is determined as follows: calculate the absolute distance between each of the fluid domain boundary grid nodes and the solid domain boundary; calculate the ratio of each of the absolute distances to the element length of the solid domain boundary; identify the maximum ratio among each of the ratios, and take the maximum ratio as the relative distance between the fluid domain boundary grid nodes and the solid domain boundary.

[0055] Wherein, the fluid domain and the solid domain are usually divided using different meshes. Even if the same mesh is used for division, node mismatches may occur at the fluid-structure interaction interface after discretization. By controlling the relative distance from the fluid domain boundary grid nodes to the solid domain boundary to be less than 1, the fluid domain and the solid domain have a better matching degree at the coupling interface. The calculation formula for the relative distance from the fluid domain boundary grid nodes to the solid domain boundary is:

[0056]

[0057] In the above formula, is the relative distance from the fluid domain boundary grid nodes to the solid domain boundary, is the absolute distance from the fluid domain boundary grid nodes to the solid domain boundary, is the element length of the solid domain boundary.

[0058] In some embodiments, the method further includes: obtaining a plurality of different mesh numbers, wherein the maximum mesh number is 3 - 4 times the minimum mesh number; based on each of the mesh numbers, performing structured mesh division on the fluid domain geometric model and the solid domain geometric model to obtain the corresponding fluid-structure interaction model; based on each of the fluid-structure interaction models, obtaining the corresponding turbulent kinetic energy distribution result of the fluid in the tank; identifying the target distribution result that meets the preset criteria among each of the turbulent kinetic energy distribution results, and determining the mesh number corresponding to the target distribution result as the target mesh number, and constructing a target fluid-structure interaction model according to the target mesh number.

[0059] Setting different mesh numbers has a great impact on the efficiency and accuracy of the simulation calculation. Too many mesh numbers will cause the simulation calculation speed to slow down, and too few mesh numbers will cause the simulation calculation accuracy to decrease. Setting the maximum mesh number to be 3 - 4 times the minimum mesh number enables covering the possible mesh sensitivity interval, which is beneficial to improving the calculation efficiency while ensuring the calculation accuracy. The turbulent kinetic energy distribution result can be used to evaluate the simulation accuracy of the fluid-structure interaction model. The more consistent the distribution of the turbulent kinetic energy is, the higher the accuracy of the fluid-structure interaction model represents. The target mesh number is the minimum mesh number under the premise of ensuring the simulation accuracy. By comparing the turbulent kinetic energy distribution results under different mesh numbers, it is beneficial to find the target mesh number that takes into account both the calculation efficiency and the accuracy.

[0060] For example, multiple different numbers of grids are obtained, which are 320,000 (denoted as partitioning scheme one), 520,000 (denoted as partitioning scheme two), 820,000 (denoted as partitioning scheme three), and 1,140,000 (denoted as partitioning scheme four) respectively. Different numbers of grids correspond to different fluid-structure interaction models. Please refer to Figures 4 - 7 , where the relative radius in the abscissa refers to the ratio of the distance from the selected point to the central axis of the tank body to the radius of the tank body. Figure 4 This is the turbulent kinetic energy distribution curve graph of partitioning scheme one provided by the embodiment of the present application. Figure 5 This is the turbulent kinetic energy distribution curve graph of partitioning scheme two provided by the embodiment of the present application. Figure 6 This is the turbulent kinetic energy distribution curve graph of partitioning scheme three provided by the embodiment of the present application. Figure 7 This is the turbulent kinetic energy distribution curve graph of partitioning scheme four provided by the embodiment of the present application. As the number of grids increases, the error becomes smaller and smaller, and the turbulent kinetic energy distribution tends to be consistent. When using partitioning scheme one and partitioning scheme two, the turbulent kinetic energy distributions on both sides of the central stirring shaft show obvious asymmetry, and there are obvious differences between the maximum and minimum values of the turbulent kinetic energy near the wall surface; when using partitioning scheme three and partitioning scheme four, the symmetry of the turbulent kinetic energy distributions on both sides of the central stirring shaft is better, and the error of the numerical simulation results of the turbulent kinetic energy at the same position is less than 10%. It can be considered that the fluid-structure interaction model using partitioning scheme three already has a relatively high accuracy.

[0061] In some embodiments, the method further includes: based on the target fluid-structure interaction model, obtaining the axial velocity simulation result of the fluid in the tank; if the error between the axial velocity simulation result and the corresponding axial velocity test result is less than the specified error, it is determined that the target fluid-structure interaction model meets the accuracy requirement.

[0062] By using the target fluid-structure interaction model, the axial velocity simulation results at different positions in the tank are obtained. By comparing with the corresponding test results, the accuracy and reliability of the target fluid-structure interaction model can be verified. Among them, the specified error can be set to 15%. Please refer to Figure 8 , Figure 8 This is the velocity distribution curve graph obtained by simulation and test provided by the embodiment of the present application. As Figure 8 shown, taking the flexible stirring mechanism of a six-blade straight vane disk turbine (abbreviated as RT) as an example, the rotational speeds are set to 150 r / min and 300 r / min respectively. By comparing the axial velocity simulation results and axial velocity test results at different positions, from Figure 8It is found that at different positions, the errors of the axial velocity distributions obtained through experiments and simulations are all kept within 15%, indicating that the target fluid-structure interaction model provided by the embodiments of the present application can relatively accurately reflect the actual flow conditions in the tank. By setting monitoring curves to obtain the flow velocity changes at different positions and comparing the obtained simulation data with the experimental data, the accuracy evaluation of the target fluid-structure interaction model is realized.

[0063] In some embodiments, the data transmission rate between the fluid domain simulation module and the solid domain simulation module is greater than 95%.

[0064] When performing the above-mentioned two-way fluid-structure interaction, within a unit time step, the liquid phase force calculated in the fluid domain simulation module is used as the first boundary condition of the solid domain simulation module and input into the solid domain simulation module for solution; within the same time step, the deformation displacement of the flexible stirring mechanism calculated in the solid domain simulation module is used as the second boundary condition of the fluid domain simulation module and input into the fluid domain simulation module for calculation. By monitoring the data transmission rate between the fluid domain simulation module and the solid domain simulation module and keeping it above 95%, it shows that there is a good data transmission effect, which is beneficial to ensuring the reliability of the simulation.

[0065] In some embodiments, constructing the fluid domain simulation module in the tank includes: setting the fluid in the tank as a single-phase fluid; using the standard k-epsilon two-equation model to simulate the turbulent characteristics of the fluid in the tank; using the SIMPLE algorithm, second-order pressure spatial discretization, and second-order upwind spatial discretization of momentum to perform simulation analysis on the fluid in the tank.

[0066] Among them, when constructing the fluid domain simulation module, it is first necessary to determine the reaction system. The embodiments of the present application simulate the anaerobic ethanol bioreaction process, and the fermentation raw material is the filtered fermentation broth. Therefore, in the fluid domain simulation module, the fluid in the tank is set as a single-phase reaction system. At the same time, there are various turbulent models and solution algorithms for solving. The embodiments of the present application select the standard k-epsilon two-equation turbulent model, the SIMPLE algorithm, and the second-order discretization format to improve the solution accuracy of the fluid domain simulation module, and those skilled in the art can select according to actual needs.

[0067] In some embodiments, in the fluid domain simulation model, based on the pressure-based multithreaded parallel transient solution, the stirring power is monitored to judge the solution progress, and a stable flow field data solution set is obtained after the solution is completed. Based on the stable flow field data solution set, the fluid-structure two-way coupling is performed, which can improve the simulation efficiency.

[0068] In some embodiments, the method further includes: combining tanks with different structures and stirring mechanisms of different types to obtain multiple different tank-stirring mechanism combinations; for each group of the tank-stirring mechanism combinations, generating corresponding flow characteristic analysis results based on the fluid-structure interaction model; and determining a target tank-stirring mechanism combination based on each of the flow characteristic analysis results.

[0069] Different tank-stirring mechanism combinations will have a greater impact on the flow characteristics inside the tank, thereby affecting the productivity of the entire fermentation process and the power consumption of the equipment. For the flexible stirring mechanism, the corresponding flow characteristic analysis results can be directly obtained through simulation analysis using the above fluid-structure interaction model. For the rigid stirring mechanism, since its impeller blades are rigid and do not deform under the action of the fluid, based on the above fluid-structure interaction model, the fluid-structure interaction part needs to be removed and then the corresponding flow characteristic analysis results are obtained through simulation. By performing simulations on different tank-stirring mechanism combinations respectively, the corresponding flow characteristic analysis results are obtained. Based on each of the flow characteristic analysis results, the optimal target tank-stirring mechanism combination is determined.

[0070] Please refer to Figures 9 - 12 , Figure 9 which is the in-tank velocity distribution contour map of the rigid six-straight-blade disk turbine impeller provided by the embodiment of the present application at a rotational speed of 150 r / min; Figure 10 which is the in-tank velocity distribution contour map of the flexible six-straight-blade disk turbine impeller provided by the embodiment of the present application at a rotational speed of 150 r / min; Figure 11 which is the in-tank velocity distribution contour map of the rigid six-straight-blade disk turbine impeller provided by the embodiment of the present application at a rotational speed of 300 r / min; Figure 12 which is the in-tank velocity distribution contour map of the flexible six-straight-blade disk turbine impeller provided by the embodiment of the present application at a rotational speed of 300 r / min. As Figures 9 - 12 shown, at the same rotational speed, when a flexible stirring mechanism is adopted, the circulation below the impeller blades can better penetrate through the bottom of the fermentation tank and the area below the impeller blades, and can better circulate the materials in this area. Its circulation effect is significantly enhanced compared with that when a rigid stirring mechanism is adopted, avoiding the existence of stirring blind spots that cannot be reached by the circulation, which results in a low proportion of some materials participating in the reaction. When the stirring rotational speed is further increased, when a flexible stirring mechanism is adopted, the circulation effect below the stirring impeller blades is further enhanced, and the optimized mass transfer characteristics of the flexible stirring mechanism are more significant.

[0071] In some embodiments, in the process of determining the optimal combination of the target tank body - stirring mechanism, it is also necessary to comprehensively consider according to the equipment test results, that is, it is necessary to consider the product output and the power consumption per unit product (the equipment power consumption when producing a unit product). In the embodiments of the present application, the power consumption per unit product is selected as an index to evaluate the working effects of fermenters equipped with different stirring mechanisms. Among them, the power consumption per unit product is calculated by the formula:

[0072]

[0073] In the above formula, is the motor speed, is the torque value under the load condition, is the torque value under the no-load condition, is the volume of the material to be stirred, is the total mass of the produced product.

[0074] In some embodiments, the simulated working conditions of different combinations of tank body - stirring mechanism are shown in Table 1.

[0075] Table 1

[0076]

[0077] As shown in Table 1, a total of eight simulated working conditions are defined. Among them, the rigid fermenter and the flexible fermenter respectively correspond to four simulated working conditions. The four simulated working conditions corresponding to the rigid fermenter are: simulated working condition 1, 2, 5, 6. Among them, in simulated working condition 1, a rigid six-straight-blade disk turbine impeller is used; the liquid phase viscosity is 15 mPa·s; in simulated working condition 2, a rigid six-straight-blade disk turbine impeller is used and the liquid phase viscosity is 50 mPa·s; in simulated working condition 5, a rigid six-inclined-blade turbine impeller is used and the liquid phase viscosity is 15 mPa·s; in simulated working condition 6, a rigid six-inclined-blade turbine impeller is used and the liquid phase viscosity is 50 mPa·s. The four simulated working conditions corresponding to the flexible fermenter are: simulated working condition 3, 4, 7, 8. Among them, in simulated working condition 3, a flexible six-straight-blade disk turbine impeller is used and the liquid phase viscosity is 15 mPa·s; in simulated working condition 4, a flexible six-straight-blade disk turbine impeller is used and the liquid phase viscosity is 50 mPa·s; in simulated working condition 7, a flexible six-inclined-blade turbine impeller is used and the liquid phase viscosity is 15 mPa·s; in simulated working condition 8, a flexible six-inclined-blade turbine impeller is used and the liquid phase viscosity is 50 mPa·s.

[0078] Please refer to Figure 13 and Figure 14 , Figure 13 is a comparison chart of the power consumption per unit product under different simulated working conditions with a liquid phase viscosity of 15 mPa provided by the embodiments of the present application. Figure 14 is a comparison chart of the power consumption per unit product under different simulated working conditions with a liquid phase viscosity of 50 mPa provided by the embodiments of the present application. As Figure 13As shown in the figure, during the anaerobic ethanol production process, with the increase of the stirring speed, the power consumption per unit product shows an exponential growth pattern. The faster the stirring speed, the greater the increase in the power consumption per unit product. At the same viscosity, by comparing the power consumption per unit product of rigid and flexible stirring mechanisms with the same type of stirring mechanism, it is found that using a flexible stirring mechanism can effectively reduce the power consumption per unit product. At different viscosities, by comparing the contribution rate of the flexible stirring mechanism to reducing the equipment power consumption with the same type of stirring mechanism, it is found that when the liquid phase viscosity is 15 mPa, using a flexible stirring mechanism can reduce the power consumption per unit product by 3% - 6%, and when the liquid phase viscosity is 50 mPa, using a flexible stirring mechanism can reduce the power consumption per unit product by 8% - 15%. Therefore, using a flexible stirring mechanism can effectively reduce the equipment power consumption and production cost during the anaerobic ethanol production process, and this optimization effect is more significant when the liquid phase viscosity is higher.

[0079] In summary, according to the simulation results of the fluid - solid coupling model, the mass transfer effect of the flexible stirring mechanism is better than that of the rigid stirring mechanism; according to the experimental analysis of different tank - stirring mechanism combinations, using a flexible stirring mechanism can effectively reduce the power consumption per unit product. Combining the simulation results and experimental results of the fluid - solid coupling model, the target tank - stirring mechanism combination with good mass transfer effect and low equipment power consumption can be determined.

[0080] It should be understood that there are various software for constructing geometric models. For example, Solidworks, SpaceClaim, DesignModel, etc. can be used to construct the geometric models of the fluid domain and the solid domain; there are various software for structured mesh generation. For example, ICEM, HyperMesh, etc. can be used for structured mesh generation, and Fluent Meshing, ANSYS Meshing can be used for unstructured mesh generation; there are various software for simulation calculations. For example, ANSYS, COMSOL, OpenForm, etc. can be used to simulate the flow characteristics in the tank, and those skilled in the art can select according to actual needs.

[0081] The embodiment of the present application also provides a method for designing a bioreactor, which applies the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism as described above.

[0082] The further function descriptions of the above - mentioned various modules and units are the same as those in the corresponding above - mentioned embodiments, and will not be repeated here.

[0083] The fluid-structure interaction model in this embodiment is presented in the form of functional units. Here, the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and a memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0084] Please refer to Figure 15 , Figure 15 which is a schematic structural diagram of a computer device provided by an embodiment of the present application. As Figure 15 shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including a high-speed interface and a low-speed interface. Each component communicates with each other using different buses and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed within the computer device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some alternative embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a set of blade servers, or a multi-processor system). Figure 15 In

[0085] which, a processor 10 is taken as an example.

[0086] The processor 10 can be a central processing unit, a network processor, or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above hardware chip can be an application specific integrated circuit, a programmable logic device, or a combination thereof. The above programmable logic device can be a complex programmable logic device, a field programmable gate array, a general array logic, or any combination thereof.

[0087] The memory 20 may include a program storage area and a data storage area. The program storage area may store an operating system and application programs required for at least one function. The data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 may optionally include a memory remotely disposed relative to the processor 10, and these remote memories may be connected to the computer device through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0088] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk, or a solid-state drive; the memory 20 may further include a combination of the above types of memories.

[0089] The computer device further includes a communication interface 30 for communicating the computer device with other devices or a communication network.

[0090] The embodiments of the present application further provide a computer-readable storage medium. The methods according to the embodiments of the present application may be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the methods described herein can be stored in such software processed on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium may be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium may also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by the computer, the processor, or the hardware, the methods shown in the above embodiments are implemented.

[0091] The embodiments of the present application provide a computer program product. The computer program product includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the methods of any embodiment of the present application.

[0092] The models or modules illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0093] For the convenience of description, when describing the above modules, they are divided into various units according to their functions for separate description. Of course, when implementing the present application, the functions of each unit can be implemented in one or more software and / or hardware.

[0094] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a model, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0095] The present application is described with reference to the flowcharts and / or block diagrams of methods, models, and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0096] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0097] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or steps for implementing the functions specified in one block or multiple blocks.

[0098] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, commodity or device comprising the said element.

[0099] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments.

[0100] The above are only the embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

[0101] Although the embodiments of the present application are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A method for analyzing the flow characteristics in a tank under the action of a flexible stirring mechanism, characterized in that The method includes: Constructing a fluid domain simulation module inside the tank and a solid domain simulation module of the flexible stirring mechanism, including obtaining a geometric model of the fluid domain inside the tank and a geometric model of the solid domain of the flexible stirring mechanism; performing structured grid division on the geometric model of the fluid domain and the geometric model of the solid domain to obtain a fluid domain grid and a solid domain grid respectively; constructing the fluid domain simulation module based on the fluid domain grid; constructing the solid domain simulation module based on the solid domain grid; by controlling the relative distance between the boundary grid nodes of the fluid domain grid and the solid domain boundary of the solid domain grid to be less than 1, enabling the fluid domain grid and the solid domain grid to be mesh-matched at the fluid-structure interaction interface, and the data transfer rate between the fluid domain simulation module and the solid domain simulation module to be greater than 95%; Among them, the relative distance between the boundary grid nodes of the fluid domain grid and the solid domain boundary of the solid domain grid is determined in the following manner: calculating the absolute distance between each of the boundary grid nodes of the fluid domain grid and the solid domain boundary; calculating the ratio of each of the absolute distances to the element length of the solid domain boundary; identifying the maximum ratio among each of the ratios, and taking the maximum ratio as the relative distance between the boundary grid node and the solid domain boundary; Generating a liquid-phase acting force based on the fluid domain simulation module, and iterating the first boundary condition of the solid domain simulation module based on the liquid-phase acting force; Generating the deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating the second boundary condition of the fluid domain simulation module based on the deformation displacement; Constructing a fluid-structure interaction model based on the fluid domain simulation module and the solid domain simulation module, and obtaining a flow characteristic analysis result based on the fluid-structure interaction model.

2. The method according to claim 1, characterized in that, The minimum orthogonality quality of the discrete elements in the fluid domain grid and the solid domain grid is greater than 0.35, the average orthogonality quality is greater than 0.9, the maximum skewness is less than 0.65, and the average skewness is less than 0.

15.

3. The method according to claim 1, wherein The method further includes: Obtaining multiple different numbers of grids, where the maximum number of grids is 3 - 4 times the minimum number of grids; Based on each number of grids, performing structured grid division on the geometric model of the fluid domain and the geometric model of the solid domain to obtain the corresponding fluid-structure interaction model; Based on each of the fluid-structure interaction models, obtaining the corresponding turbulent kinetic energy distribution result of the fluid inside the tank; Identifying a target distribution result that meets a preset standard among each of the turbulent kinetic energy distribution results, and determining the number of grids corresponding to the target distribution result as the target number of grids, and constructing a target fluid-structure interaction model according to the target number of grids.

4. The method according to claim 3, characterized in that, The method further includes: Obtaining the axial velocity simulation result of the fluid inside the tank based on the target fluid-structure interaction model; If the error between the axial velocity simulation result and the corresponding axial velocity test result is less than a specified error, it is determined that the target fluid-structure interaction model meets the accuracy requirements.

5. The method according to claim 4, wherein The specified error is set to 15%.

6. The method according to any one of claims 1-5, characterized in that, Constructing the fluid domain simulation module inside the tank includes: Setting the fluid inside the tank as a single-phase fluid; The standard k-epsilon two-equation model is used to simulate the turbulent characteristics of the fluid in the tank; The SIMPLE algorithm, second-order pressure spatial discretization, and second-order upwind spatial discretization of momentum are used to perform simulation analysis on the fluid in the tank.

7. The method according to claim 1, characterized in that The method further includes: Combining tanks with different structures and stirring mechanisms of different types to obtain multiple groups of different tank-stirring mechanism combinations; For each group of the tank-stirring mechanism combinations, based on the fluid-structure interaction model, corresponding flow characteristic analysis results are generated; Based on each of the flow characteristic analysis results, a target tank-stirring mechanism combination is determined.

8. A method for designing a biological fermentation tank, characterized in that, Apply the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism according to any one of claims 1-7.

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