In-tank flow characteristic analysis method under action of flexible stirring mechanism and application of in-tank flow characteristic analysis method

Abstract

The invention relates to the technical field of biological fermentation, and discloses a method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism and application of the method, and the method comprises the following steps: 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 a first boundary condition of the solid domain simulation module based on the liquid phase acting force; generating deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating a second boundary condition of the fluid domain simulation module based on the deformation displacement; and constructing a fluid-solid coupling model on the basis of the fluid domain simulation module and the solid domain simulation module, and obtaining a flow characteristic analysis result on the basis of the fluid-solid coupling model, thereby solving the technical problem of how to accurately simulate the in-tank flow characteristics under the action of the flexible stirring mechanism.

Description

Technical Field

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

[0002] According to the 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 external force to the fermentation liquid, so that better flow effect can be obtained. The strong shearing effect 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 the stirring process. The blade of the flexible stirring mechanism is a flexible blade with good flexibility and elasticity, and will produce a certain deformation during the stirring process. The deformation of the flexible blade can enhance the disturbance of the fluid and improve the mixing efficiency. However, the relevant simulation method cannot accurately reflect the flow characteristics in the tank under the action of the flexible stirring mechanism. Summary of the invention

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

[0004] In order to achieve the above objectives, the main technical solutions adopted in this application include: In the first aspect, an embodiment of the present application provides a method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism, the method comprising: constructing a fluid domain simulation module in the tank and a solid domain simulation module of the flexible stirring mechanism; based on the fluid domain simulation module, generating a liquid phase force, and based on the liquid phase force, iterating a first boundary condition of the solid domain simulation module; based on the solid domain simulation module, generating a deformation displacement of the flexible stirring mechanism, and based on the deformation displacement, iterating a second boundary condition of the fluid domain simulation module; based on the fluid domain simulation module and the solid domain simulation module, constructing a fluid-solid coupling model, and based on the fluid-solid coupling model, obtaining flow characteristics analysis results.

[0005] The method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism provided in this embodiment 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 force based on the fluid domain simulation module, and iterating a first boundary condition of the solid domain simulation module based on the liquid phase force; generating a deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating a second boundary condition of the fluid domain simulation module based on the deformation displacement; constructing a fluid-solid coupling model based on the fluid domain simulation module and the solid domain simulation module, and obtaining flow characteristic analysis results based on the fluid-solid coupling model, thereby solving the technical problem of how to accurately simulate the flow characteristics in the tank under the action of a flexible stirring mechanism.

[0006] Optionally, constructing a fluid domain simulation module for the fluid in the tank and a solid domain simulation module for the flexible stirring mechanism includes: acquiring a fluid domain geometric model in the tank and a solid domain geometric model of the flexible stirring mechanism; performing structured meshing on the fluid domain geometric model and the solid domain geometric model to obtain a fluid domain mesh and a solid domain mesh, respectively; constructing the fluid domain simulation module based on the fluid domain mesh; and constructing the solid domain simulation module based on the solid domain mesh.

[0007] Optionally, the minimum orthogonal quality of discrete units 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 node and the solid domain boundary is less than 1, wherein the solid domain boundary is determined by the solid domain geometric model.

[0008] Optionally, the relative distance between the fluid domain boundary grid node and the solid domain boundary is determined in the following manner: calculating the absolute distance between each of the fluid domain boundary grid nodes and the solid domain boundary; calculating the ratio of each of the absolute distances to the unit length of the solid domain boundary; identifying the maximum ratio among the ratios, and using the maximum ratio as the relative distance between the fluid domain boundary grid node and the solid domain boundary.

[0009] Optionally, the method also includes: obtaining multiple different grid numbers, wherein the maximum grid number is 3-4 times the minimum grid number; based on each of the grid numbers, performing structured grid division on the fluid domain geometric model and the solid domain geometric model to obtain the corresponding fluid-solid coupling model; based on each of the fluid-solid coupling models, obtaining the corresponding turbulent kinetic energy distribution result of the fluid in the tank; identifying the target distribution result that meets the preset standard in each of the turbulent kinetic energy distribution results, and determining the grid number corresponding to the target distribution result as the target grid number, and constructing the target fluid-solid coupling model according to the target grid number.

[0010] Optionally, the method further includes: obtaining an axial velocity simulation result of the fluid in the tank based on the target fluid-solid coupling 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-solid coupling model meets the accuracy requirements.

[0011] 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%.

[0012] Optionally, construct a fluid domain simulation module in the tank, including: setting the fluid in the tank as a single-phase fluid; using a standard k-epsilon two-equation model to simulate the turbulent characteristics of the fluid in the tank; and using a SIMPLE algorithm, a second-order spatial discretization of pressure format, and a second-order upwind spatial discretization of momentum to simulate and analyze the fluid in the tank.

[0013] Optionally, the method further includes: combining tanks with different structures and different types of stirring mechanisms to obtain multiple groups of different tank-stirring mechanism combinations; for each group of the tank-stirring mechanism combinations, generating corresponding flow characteristic analysis results based on the fluid-solid coupling model; and determining the target tank-stirring mechanism combination based on each of the flow characteristic analysis results.

[0014] In a second aspect, an embodiment of the present application provides a method for designing a biological fermentation tank, which uses the method for analyzing flow characteristics within the tank under the action of the above-mentioned flexible stirring mechanism.

[0015] In a third aspect, an embodiment of the present application provides a computer device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the above-mentioned method for analyzing flow characteristics in a tank under the action of the flexible stirring mechanism by executing the computer instructions.

[0016] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having computer instructions stored thereon, wherein the computer instructions are used to enable a computer to execute the method for analyzing flow characteristics within a tank under the action of the above-mentioned flexible stirring mechanism.

[0017] In a fifth aspect, an embodiment of the present application provides a computer program product, comprising computer instructions, wherein the computer instructions are used to enable a computer to execute the above-mentioned method for analyzing flow characteristics in a tank under the action of the flexible stirring mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A flow chart of a method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism provided in an embodiment of the present application; Figure 2 A schematic diagram of a fluid domain grid provided in an embodiment of the present application; Figure 3 A schematic diagram of a solid domain grid provided in an embodiment of the present application; Figure 4 A turbulent kinetic energy distribution curve diagram of the division scheme 1 provided in the embodiment of the present application; Figure 5 A turbulent kinetic energy distribution curve diagram of the second division scheme provided in the embodiment of the present application; Figure 6 A turbulent kinetic energy distribution curve diagram of the division scheme 3 provided in the embodiment of the present application; Figure 7 A turbulent kinetic energy distribution curve diagram of the fourth division scheme provided in the embodiment of the present application; Figure 8 A velocity distribution curve obtained by simulation and experiment provided in the embodiment of the present application; Fig. 9 A velocity distribution cloud diagram of a rigid six-straight-blade disc turbine impeller provided in an embodiment of the present application at a rotation speed of 150 r / min in a tank; Fig.10 A cloud diagram of the velocity distribution in the tank of the flexible six-straight-blade disc turbine provided in the embodiment of the present application at a rotation speed of 150 r / min; Fig.11 A velocity distribution cloud diagram of a rigid six-straight-blade disc turbine provided in an embodiment of the present application at a rotation speed of 300 r / min in a tank; Fig.12 A velocity distribution cloud diagram of the flexible six-straight-blade disc turbine provided in an embodiment of the present application at a rotation speed of 300 r / min in the tank; Fig.13 A comparison chart of unit product power consumption under different simulated working conditions with a liquid viscosity of 15 mPa provided in the embodiment of the present application; Fig.14 A comparison chart of unit product power consumption under different simulated working conditions with a liquid viscosity of 50 mPa provided in the embodiment of the present application; Fig.15It is a structural diagram of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0021] Under the global background of greenhouse effect and environmental pollution, fuel ethanol has shown great application potential and market value in replacing traditional fossil fuels. At present, fuel ethanol is usually produced by anaerobic fermentation using biological methods. The raw materials of fermentation liquid mainly come from agricultural waste including straw, beets, sorghum, and rotten fruits. The fermentation steps include raw material processing, 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 the different mechanisms of action, the relevant fermentation methods can be divided into two types: mechanical stirring fermentation method and pit composting fermentation method. The mechanical stirring fermentation method applies external force to the fermentation liquid, so as to obtain better flow effect.

[0022] The fermentation tank in the mechanical stirring fermentation method includes a tank body and a stirring mechanism. The stirring mechanism includes a blade and a stirring shaft. According to the different materials of the blades, 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 blade material of the rigid stirring mechanism is a rigid material, which can maintain a stable shape and structure during the stirring process. The blade material of the flexible stirring mechanism is a flexible blade, which has good flexibility and elasticity and will produce a certain deformation during the stirring process. The deformation of the flexible blade can enhance the disturbance of the fluid and improve the mixing efficiency. The strong shearing effect 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. However, the relevant simulation method cannot accurately reflect the flow characteristics in the tank under the action of the flexible stirring mechanism.

[0023] An embodiment of the present application provides a method for analyzing 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 a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0024] Please refer to Figure 1 , Figure 1 : is a flow chart of a method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism provided in an embodiment of the present application. Figure 1 As shown, the process includes the following steps: Step S1, constructing a fluid domain simulation module in the tank and a solid domain simulation module of the flexible stirring mechanism.

[0025] Among them, there is a fluid (which can be a fermentation liquid) in the tank, and the fluid domain refers to the space area occupied by the fluid in the tank. The fluid domain simulation module is used to simulate or calculate the flow characteristics, pressure distribution, temperature change and other physical quantities of the fluid in the tank. The solid domain refers to the space area occupied by the flexible stirring mechanism. The flexible stirring mechanism includes a stirring shaft, a flexible blade and a connecting part for connecting the two. The solid domain simulation module is used to simulate or calculate the stress, strain, deformation and other physical quantities of the flexible stirring mechanism. There is an interaction between the fluid and the flexible stirring mechanism.

[0026] Step S3: Generate liquid phase force based on the fluid domain simulation module, and iterate the first boundary condition of the solid domain simulation module based on the liquid phase force.

[0027] The liquid phase force refers to the force exerted by the fluid in the tank on the boundary of the solid domain. The flow field is calculated using the fluid domain simulation model to obtain the flow field data solution set. The liquid phase force in the flow field data solution set is extracted, and the first boundary condition (i.e., mechanical boundary condition) of the solid domain simulation module is iterated based on the liquid phase force to reflect the influence of the flow field on the deformation of the flexible blade.

[0028] Step S5: generating a deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating a second boundary condition of the fluid domain simulation module based on the deformation displacement.

[0029] Among them, the liquid phase force generated by the fluid will cause the flexible blade to deform and produce deformation displacement. The deformation of the flexible blade will in turn affect the flow field. In the solid domain simulation module, the deformation displacement of the flexible stirring mechanism under the action of the fluid is calculated. Based on the deformation displacement, the second boundary condition of the fluid domain simulation module is iterated to reflect the influence of the deformation of the flexible blade on the fluid flow field.

[0030] Step S7, constructing a fluid-solid coupling model based on the fluid domain simulation module and the solid domain simulation module, and obtaining flow characteristic analysis results based on the fluid-solid coupling model.

[0031] Among them, the fluid-solid coupling model is used to simultaneously analyze how the flow of the fluid affects the deformation of the flexible stirring mechanism, and how the deformation of the flexible stirring mechanism in turn affects the flow of the fluid. The flow characteristics analysis results include flow velocity distribution, etc. By constructing the fluid-solid coupling model, an accurate simulation of the influence of the flexible stirring mechanism on the flow characteristics of the fluid in the tank is achieved, which can be used to optimize the fermentation tank, including the design of the tank body and the flexible stirring mechanism, and improve the mass transfer effect.

[0032] 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. Repeating steps S3-S5, bidirectional fluid-solid coupling is achieved, and the flow characteristics of the fluid in the tank are analyzed based on the converged fluid-solid coupling model.

[0033] The method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism provided in this embodiment 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 force based on the fluid domain simulation module, and iterating a first boundary condition of the solid domain simulation module based on the liquid phase force; generating a deformation displacement of the flexible stirring mechanism based on the solid domain simulation module, and iterating a second boundary condition of the fluid domain simulation module based on the deformation displacement; constructing a fluid-solid coupling model based on the fluid domain simulation module and the solid domain simulation module, and obtaining flow characteristic analysis results based on the fluid-solid coupling model, thereby solving the technical problem of how to accurately simulate the flow characteristics in the tank under the action of a flexible stirring mechanism.

[0034] In some embodiments, constructing a fluid domain simulation module for the fluid in the tank and a solid domain simulation module for the flexible stirring mechanism includes: acquiring a fluid domain geometric model in the tank and a solid domain geometric model of the flexible stirring mechanism; performing structured meshing on the fluid domain geometric model and the solid domain geometric model to obtain a fluid domain mesh and a solid domain mesh, respectively; constructing the fluid domain simulation module based on the fluid domain mesh; and constructing the solid domain simulation module based on the solid domain mesh.

[0035] Among them, structured meshing includes two steps: regular division and structured discretization. Regularly divide the fluid domain geometry model and the solid domain geometry model so that they are composed of several geometric bodies with regular shapes, which is conducive to the subsequent structured discretization. Structured discretization is performed on the regularly divided fluid domain geometry model and solid domain geometry model to form structured fluid domain mesh and solid domain mesh. Please refer to Figure 2 and Figure 3 , Figure 2 A schematic diagram of a fluid domain grid provided in an embodiment of the present application, Figure 3Schematic diagram of the solid domain mesh provided in the embodiment of the present application. For example, for a six-blade disc turbine rigid fermenter, its fluid domain mesh is as follows Figure 2 As shown, the inner diameter of the tank is 300 mm, the height of the liquid phase in the tank is 300 mm, and the inner wall of the tank is equipped with four sets of baffles with a width of 30 mm, a height of 300 mm, and a thickness of 4 mm; its solid domain mesh is as follows Figure 3 As shown, the corresponding stirring mechanism uses a central axis six straight blade disc turbine 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 division on the fluid domain geometric model and the solid domain geometric model, the grid of the interface between the fluid domain and the solid domain is matched, which is conducive to improving computational efficiency and accuracy.

[0036] In some embodiments, the minimum orthogonal quality of discrete cells 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 node and the solid domain boundary is less than 1, wherein the solid domain boundary is determined by the solid domain geometric model.

[0037] Among them, after the fluid domain and solid domain are divided and discretized regularly, the minimum orthogonal quality of the discrete unit 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, so as to ensure the mesh quality of the fluid domain mesh and the solid domain mesh, which is conducive to ensuring the simulation accuracy. The relative distance between the fluid domain boundary mesh node and the solid domain boundary in the fluid domain mesh is set to be less than 1, so that the fluid domain and the solid domain have a good match at the fluid-solid coupling interface.

[0038] In some embodiments, the relative distance between the fluid domain boundary grid node and the solid domain boundary is determined in the following manner: calculating the absolute distance between each of the fluid domain boundary grid nodes and the solid domain boundary; calculating the ratio of each of the absolute distances to the unit length of the solid domain boundary; identifying the maximum ratio among the ratios, and using the maximum ratio as the relative distance between the fluid domain boundary grid node and the solid domain boundary.

[0039] The fluid domain and the solid domain are usually divided by different grids. Even if the same grid is used, there may be node mismatch problems at the fluid-solid coupling interface after discretization. By controlling the relative distance from the fluid domain boundary grid node to the solid domain boundary to be less than 1, the fluid domain and the solid domain have a better match at the coupling interface. The calculation formula for the relative distance from the fluid domain boundary grid node to the solid domain boundary is: In the above formula, is the relative distance from the boundary mesh node of the fluid domain to the boundary of the solid domain, is the absolute distance from the boundary mesh node of the fluid domain to the boundary of the solid domain, is the element length at the boundary of the solid domain.

[0040] In some embodiments, the method also includes: obtaining multiple different grid numbers, wherein the maximum grid number is 3-4 times the minimum grid number; based on each of the grid numbers, performing structured grid division on the fluid domain geometric model and the solid domain geometric model to obtain the corresponding fluid-solid coupling model; based on each of the fluid-solid coupling models, obtaining the corresponding turbulent kinetic energy distribution result of the fluid in the tank; identifying the target distribution result that meets the preset standard in each of the turbulent kinetic energy distribution results, and determining the grid number corresponding to the target distribution result as the target grid number, and constructing the target fluid-solid coupling model according to the target grid number.

[0041] Setting different numbers of grids has a great impact on the efficiency and accuracy of simulation calculations. Too many grids will slow down the simulation calculations, and too few grids will reduce the accuracy of simulation calculations. Setting the maximum number of grids to 3-4 times the minimum number of grids so that the possible grid sensitivity range is covered is conducive to improving calculation efficiency while ensuring calculation accuracy. The turbulent kinetic energy distribution results can be used to evaluate the simulation accuracy of the fluid-solid coupling model. The more consistent the distribution of turbulent kinetic energy is, the higher the accuracy of the fluid-solid coupling model. The target number of grids is the minimum number of grids under the premise of ensuring simulation accuracy. By comparing the turbulent kinetic energy distribution results under different numbers of grids, it is helpful to find the target number of grids that takes into account both calculation efficiency and accuracy.

[0042] For example, we can obtain multiple different numbers of grids, which are 320,000 (recorded as division scheme 1), 520,000 (recorded as division scheme 2), 820,000 (recorded as division scheme 3), and 1.14 million (recorded as division scheme 4). Different numbers of grids correspond to different fluid-structure interaction models. Please refer to Figure 4-Figure 7 , where the relative radius in the horizontal axis refers to the ratio of the distance from the point to the central axis of the tank to the radius of the tank. Figure 4 This is a turbulent kinetic energy distribution curve diagram of the division scheme 1 provided in the embodiment of the present application, Figure 5 This is a turbulent kinetic energy distribution curve diagram of the second division scheme provided in the embodiment of the present application, Figure 6 This is a turbulent kinetic energy distribution curve diagram of the division scheme 3 provided in the embodiment of the present application, Figure 7 The turbulent kinetic energy distribution curve of the division scheme four provided in 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 division schemes one and two, the turbulent kinetic energy distribution on both sides of the central stirring shaft shows obvious asymmetry, and there is a significant difference between the maximum and minimum turbulent kinetic energy near the wall; when using division schemes three and four, the turbulent kinetic energy distribution on both sides of the central stirring shaft is better in symmetry, and the error of the numerical simulation results of turbulent kinetic energy at the same position is less than 10%. It can be considered that the fluid-solid coupling model using division scheme three has a higher accuracy.

[0043] In some embodiments, the method further includes: obtaining an axial velocity simulation result of the fluid in the tank based on the target fluid-solid coupling 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-solid coupling model meets the accuracy requirements.

[0044] Through the target fluid-structure coupling 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 coupling model can be verified. The specified error can be set to 15%. Please refer to Figure 8 , Figure 8 The velocity distribution curve obtained by simulation and experiment provided in the embodiment of the present application is shown in FIG. Figure 8 As shown in the figure, taking the flexible stirring mechanism of six straight-blade disc turbine (abbreviated as RT) as an example, the rotation speeds are set to 150 r / min and 300 r / min respectively, and the axial velocity simulation results and axial velocity test results at different positions are compared. Figure 8 It is found that the errors of the axial velocity distribution obtained by experiment and simulation at different positions are kept within 15%, indicating that the target fluid-solid coupling model provided by the embodiment of the present application can more accurately reflect the flow conditions in the real tank. By setting the monitoring curve 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-solid coupling model is achieved.

[0045] In some embodiments, the data transmission rate between the fluid domain simulation module and the solid domain simulation module is greater than 95%.

[0046] When performing the above-mentioned bidirectional fluid-solid coupling, 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, it is kept above 95%, indicating that it has a good data transmission effect, which is conducive to ensuring the reliability of the simulation.

[0047] In some embodiments, a fluid domain simulation module in the tank is constructed, including: setting the fluid in the tank to a single-phase fluid; using a standard k-epsilon two-equation model to simulate the turbulent characteristics of the fluid in the tank; and using a SIMPLE algorithm, a second-order spatial discretization of pressure format, and a second-order upwind spatial discretization of momentum to simulate and analyze the fluid in the tank.

[0048] Among them, when constructing the fluid domain simulation module, the reaction system must be determined first. The embodiment of this application simulates the anaerobic ethanol biological fermentation process, and the fermentation raw material is the filtered fermentation liquid. Therefore, in the fluid domain simulation module, the fluid in the tank is set to a single-phase reaction system. At the same time, there are many turbulence models and solution algorithms for solving. The embodiment of this application uses the standard k-epsilon two-equation turbulence model, SIMPLE algorithm, and second-order discrete format to improve the solution accuracy of the fluid domain simulation module. Those skilled in the art can choose according to actual needs.

[0049] In some embodiments, in the fluid domain simulation model, a multi-threaded parallel transient solution based on a pressure basis is used, and stirring power monitoring is used to determine the solution progress. After the solution is completed, a stable flow field data solution set is obtained. Based on the stable flow field data solution set, fluid-solid bidirectional coupling is performed to improve the efficiency of the simulation.

[0050] In some embodiments, the method further includes: combining tanks of different structures and different types of stirring mechanisms to obtain multiple groups of different tank-stirring mechanism combinations; for each group of the tank-stirring mechanism combinations, generating corresponding flow characteristic analysis results based on the fluid-solid coupling model; and determining the target tank-stirring mechanism combination based on each of the flow characteristic analysis results.

[0051] Different tank-stirring mechanism combinations will have a significant impact on the flow characteristics in the tank, and thus affect the yield 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 the simulation analysis of the above-mentioned fluid-solid coupling model. For the rigid stirring mechanism, since its blades are rigid and do not deform under the action of the fluid, on the basis of the above-mentioned fluid-solid coupling model, the fluid-solid coupling part needs to be removed, and then the corresponding flow characteristic analysis results need to be simulated. By simulating 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.

[0052] Please refer to Figure 9-12 , Fig. 9 A velocity distribution cloud diagram of a rigid six-straight-blade disc turbine provided in an embodiment of the present application at a rotation speed of 150 r / min in a tank; Fig.10 A cloud diagram of the velocity distribution in the tank of the flexible six-straight-blade disc turbine provided in the embodiment of the present application at a rotation speed of 150 r / min; Fig.11 A velocity distribution cloud diagram of a rigid six-straight-blade disc turbine provided in an embodiment of the present application at a rotation speed of 300 r / min in a tank; Fig.12 This is a velocity distribution cloud diagram of the flexible six straight blade disc turbine provided in the embodiment of the present application at a speed of 300 r / min. Figure 9-12 As shown in the figure, at the same speed, when a flexible stirring mechanism is used, the circulation under the blades can better penetrate the bottom of the fermenter and the area under the blades, and can better circulate the materials in this area. The circulation effect is significantly enhanced compared to the rigid stirring mechanism, avoiding the existence of a stirring blind area that cannot be reached by the circulation, resulting in a low proportion of some materials participating in the reaction. When the stirring speed is further increased, when a flexible stirring mechanism is used, the circulation effect under the stirring blades is further enhanced, and the optimized mass transfer characteristics of the flexible stirring mechanism are more significant.

[0053] In some embodiments, in the process of determining the optimal target tank body-stirring mechanism combination, it is also necessary to comprehensively consider the equipment test results, that is, it is necessary to consider the product output and unit product power consumption (equipment power consumption when producing unit product). The embodiment of the present application selects unit product power consumption as an indicator to evaluate the working effect of fermentation tanks equipped with different stirring mechanisms. Among them, unit product power consumption The calculation formula is: In the above formula, is the motor speed, is the torque value under load conditions, is the torque value under no-load conditions, is the volume of the material being mixed, The total quality of the produced product.

[0054] In some embodiments, the simulated working conditions of different tank-stirring mechanism combinations are shown in Table 1.

[0055] Table 1 As shown in Table 1, eight simulation conditions are defined, among which the rigid fermenter and the flexible fermenter correspond to four simulation conditions respectively. The four simulation conditions corresponding to the rigid fermenter are: simulation conditions 1, 2, 5, and 6, among which simulation condition 1 adopts a rigid six-straight-blade disc turbine propeller; the liquid phase viscosity is 15 mPa·s; simulation condition 2 adopts a rigid six-straight-blade disc turbine propeller and a liquid phase viscosity of 50 mPa·s; simulation condition 5 adopts a rigid six-slant-blade turbine propeller and a liquid phase viscosity of 15 mPa·s; simulation condition 6 adopts a rigid six-slant-blade turbine propeller and a liquid phase viscosity of 50 mPa·s. The four simulation conditions corresponding to the flexible fermentation tank are: simulation conditions 3, 4, 7, and 8. Among them, simulation condition 3 adopts a flexible six-straight-blade disc turbine propeller with a liquid phase viscosity of 15 mPa·s; simulation condition 4 adopts a flexible six-straight-blade disc turbine propeller with a liquid phase viscosity of 50 mPa·s; simulation condition 7 adopts a flexible six-slanted-blade turbine propeller with a liquid phase viscosity of 15 mPa·s; simulation condition 8 adopts a flexible six-slanted-blade turbine propeller with a liquid phase viscosity of 50 mPa·s.

[0056] Please refer to Fig.13 and Fig.14 , Fig.13 A comparison chart of unit product power consumption under different simulated working conditions with a liquid viscosity of 15 mPa provided in an embodiment of the present application. Fig.14 This is a comparison chart of unit product power consumption under different simulated working conditions with a liquid viscosity of 50 mPa provided in the embodiment of the present application. Fig.13 As shown in the figure, in the anaerobic ethanol production process, as the stirring speed increases, the power consumption per unit product shows an exponential growth law. The faster the stirring speed, the greater the increase in power consumption per unit product. Under the same viscosity, by comparing the power consumption per unit product of the rigid and flexible stirring mechanisms when the same stirring mechanism type is used, it is found that the flexible stirring mechanism can effectively reduce the power consumption per unit product. Under different viscosities, by comparing the contribution rate of the flexible stirring mechanism to reducing the power consumption of the equipment when the same stirring mechanism type is used, it is found that when the liquid phase viscosity is 15 mPa, the flexible stirring mechanism can reduce the power consumption per unit product by 3%-6%, and when the liquid phase viscosity is 50 mPa, the flexible stirring mechanism can reduce the power consumption per unit product by 8%-15%. Therefore, the use of a flexible stirring mechanism can effectively reduce the power consumption of equipment and production costs in the anaerobic ethanol production process, and this optimization effect is more significant when the liquid phase viscosity is higher.

[0057] In summary, according to the simulation results of the fluid-solid coupling model, the flexible stirring mechanism has better mass transfer effect than the rigid stirring mechanism; according to the experimental analysis of different tank-stirring mechanism combinations, the use of 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.

[0058] It should be understood that there are many kinds of software for constructing geometric models, for example, Solidworks, SpaceClaim, DesignModel, etc. can be used to construct fluid domain geometric models and solid domain geometric models; there are many kinds of software for structured meshing, for example, ICEM, HyperMesh, etc. can be used for structured meshing, and Fluent Meshing, ANSYS Meshing can be used for unstructured meshing; there are many kinds of software for simulation calculations, for example, ANSYS, COMSOL, OpenForm, etc. can be used to simulate the flow characteristics inside the tank, and technical personnel in this field can choose according to actual needs.

[0059] The embodiment of the present application also provides a method for designing a biological fermentation tank, which uses the method for analyzing the flow characteristics in the tank under the action of the flexible stirring mechanism as described above.

[0060] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0061] The fluid-structure interaction model in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0062] See also Fig.15 , Fig.15 is a schematic diagram of the structure of a computer device provided in an embodiment of the present application, such as Fig.15As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional 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 group of blade servers, or a multi-processor system). Fig.15 A processor 10 is taken as an example.

[0063] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0064] The memory 20 stores instructions executable by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0065] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application 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-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via 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.

[0066] 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 also include a combination of the above types of memory.

[0067] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0068] The embodiment of the present application also provides a computer-readable storage medium. The above method according to the embodiment of the present application can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can 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 a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0069] The embodiment of the present application provides a computer program product, which includes computer instructions, which are stored in a computer-readable storage medium. A processor of a 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 method of any embodiment of the present application.

[0070] The models or modules described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may 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.

[0071] For the convenience of description, the above modules are described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0072] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, models or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt 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.) containing computer-usable program codes.

[0073] The present application is described with reference to the flowcharts and / or block diagrams of the methods, models, and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes 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 a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0074] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0075] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0076] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity or device including the element.

[0077] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0078] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0079] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism, characterized in that: The method comprises: Constructing a fluid domain simulation module in the tank and a solid domain simulation module of the flexible stirring mechanism; Generate a liquid phase force based on the fluid domain simulation module, and iterate a first boundary condition of the solid domain simulation module based on the liquid phase force; Based on the solid domain simulation module, generating a deformation displacement of the flexible stirring mechanism, and based on the deformation displacement, iterating a second boundary condition of the fluid domain simulation module; A fluid-solid coupling model is constructed based on the fluid domain simulation module and the solid domain simulation module, and a flow characteristic analysis result is obtained based on the fluid-solid coupling model.

2. The method according to claim 1, characterized in that Constructing a fluid domain simulation module of the fluid in the tank and a solid domain simulation module of the flexible stirring mechanism, including: Acquire a fluid domain geometric model in the tank and a solid domain geometric model of the flexible stirring mechanism; Performing structured grid division on the fluid domain geometric model and the solid domain geometric model to obtain a fluid domain grid and a solid domain grid respectively; Based on the fluid domain grid, construct the fluid domain simulation module; Based on the solid domain grid, the solid domain simulation module is constructed.

3. The method according to claim 2, characterized in that The minimum orthogonal quality of the discrete units 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 node and the solid domain boundary is less than 1, wherein the solid domain boundary is determined by the solid domain geometric model.

4. The method according to claim 3, characterized in that The relative distance between the fluid domain boundary grid node and the solid domain boundary is determined as follows: Calculating the absolute distance between each of the fluid domain boundary grid nodes and the solid domain boundary; Calculating the ratio of each of the absolute distances to the unit length of the solid domain boundary; A maximum ratio among the ratios is identified, and the maximum ratio is used as the relative distance between the fluid domain boundary grid node and the solid domain boundary.

5. The method according to claim 2, characterized in that: The method further comprises: Get multiple different grid numbers, where the maximum grid number is 3-4 times the minimum grid number; Based on each of the grid numbers, structured grid division is performed on the fluid domain geometric model and the solid domain geometric model to obtain the corresponding fluid-solid coupling model; Based on each of the fluid-solid coupling models, a corresponding turbulent kinetic energy distribution result of the fluid in the tank is obtained; A target distribution result that meets a preset standard is identified in each of the turbulent kinetic energy distribution results, and the number of grids corresponding to the target distribution result is determined as the target number of grids. According to the target number of grids, a target fluid-solid coupling model is constructed.

6. The method according to claim 5, characterized in that The method further comprises: Based on the target fluid-solid coupling model, obtaining an 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 a specified error, it is determined that the target fluid-solid coupling model meets the accuracy requirement.

7. The method according to claim 6, characterized in that 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%.

8. The method according to any one of claims 1 to 7, characterized in that Construct a fluid domain simulation module in the tank, including: The fluid in the tank is set to be a single-phase fluid; A standard k-epsilon two-equation model is used to simulate the turbulent flow characteristics of the fluid in the tank; The SIMPLE algorithm, second-order spatial discretization of pressure and second-order upwind spatial discretization of momentum are used to simulate and analyze the fluid in the tank.

9. The method according to claim 1, characterized in that: The method further comprises: Combining tanks of different structures with different types of stirring mechanisms to obtain multiple groups of different tank-stirring mechanism combinations; For each tank-stirring mechanism combination, generating corresponding flow characteristic analysis results based on the fluid-solid coupling model; Based on the analysis results of each of the flow characteristics, a target tank-stirring mechanism combination is determined.

10. A method for designing a biological fermentation tank, characterized in that: A method for analyzing flow characteristics in a tank under the action of a flexible stirring mechanism as described in any one of claims 1 to 9 is used.

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