Method for detecting fluid flow field distribution in multi-tail-pipe pipeline

Abstract

The invention provides a detection method for fluid flow field distribution in a multi-tail-pipe pipeline. The detection method comprises the following steps: constructing a multi-tail-pipe pipeline model and a multi-tail-pipe fluid model; after construction is completed, the multi-tail-pipe pipeline model and the multi-tail-pipe fluid model are assembled to form a model pipeline; and then creating load and boundary conditions, introducing the load and boundary conditions into the model pipeline, and calculating fluid flow field distribution in the model pipeline to obtain a detection result. According to the detection method provided by the invention, the problem of non-uniform distribution of flow fields among a plurality of tail pipes in a polymer processing technology taking a non-Newtonian fluid as a stock solution can be well detected, and the distribution of the flow fields in the tail pipes is detected through a simulation test in combination with consideration of a plurality of parameters; and a reference scheme is provided for the improvement of a polymer processing technology according to a detection result, so that the product quality problem caused by non-uniform flow velocity distribution of different tail pipes is accurately and quickly solved, and the production efficiency is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flow field detection, and in particular, relates to a method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline. Background Art

[0002] In polymer processing technology, polymer solutions are easy to process and shape, and are often used as raw materials. However, compared with powders and particles, the flow characteristics of the polymer solutions themselves and the flow field disturbance caused by the coupling between the pipelines will also bring certain problems to the production process. For example, in the industrial spinning process, in order to improve production efficiency and save production costs, parallel spinning is usually used for production operations, that is, multiple tail pipes are used for spinning operations at the same time, which can produce more fibers in the same time. In addition, it is also beneficial to improve the stability of the production line. For example, when a single tail pipe fails, the remaining tail pipes can continue to operate, thereby improving the reliability and stability of the production system. In large-scale spinning processes, in order to improve the quality and consistency of fibers and facilitate management, the post-processing process of the solution flowing out of different tail pipes of the same fiber is basically consistent. At this time, the uniformity of the flow field distribution of the fluid between different tail pipes is extremely important. When the flow field is unevenly distributed, there will be certain differences in the liquid content flowing out of different tail pipes. Under the condition of completely consistent post-processing, if the difference in the volume of liquid flowing out at the same time is large, it will seriously affect the quality of the product. For example, in the case of polyacrylonitrile spinning carbon fiber precursor, under the same traction and coagulation bath conditions, excessive volume of fluid liquid will lead to the phenomenon of yarn doubling during the drawing process of the precursor, resulting in the failure of complete coagulation inside the fiber, resulting in broken wires during the drawing process, or contact with the spinneret under the influence of gravity, resulting in broken wires; when the volume of the outflowing liquid is small, it will cause the fiber to become locally thinner during the stretching process, resulting in stress concentration, and then causing broken wires, seriously affecting the quality of the precursor. In addition to the spinning industry, flow field disturbances can also cause serious problems in other polymer processing technologies. For example, in the process of co-extrusion to make multi-layer films, if the flow field is unevenly distributed, it will also lead to uneven thickness of a certain layer, which will affect the mechanical properties, air permeability and moisture resistance of the film; in the multi-layer pipe extrusion process, the uneven flow field may lead to poor adhesion of different material layers, resulting in stratification, which seriously affects the physical properties and service life of the pipe; in the melt extrusion process, the uneven flow field distribution may cause the melt to fail to mix fully in some areas, resulting in color difference and uneven physical properties of the final material. Therefore, polymer processing industries such as the spinning industry usually use equal length and equal distance to reduce the uneven flow field distribution caused by flow field disturbances when designing pipelines. However, the flow field distribution in the pipe is a practical problem affected by multiple factors. In addition to being affected by the pipe structure parameters, it is also related to the rheological properties of the fluid itself. In particular, most fluids in the spinning industry are non-Newtonian fluids, whose dynamic viscosity changes with the shear rate, and the disturbance of the flow field increases, further increasing the difficulty of flow field detection in the pipe. In addition, for non-Newtonian fluids, especially polymer solutions, different dynamic viscosities indicate different conformations of polymer segments, and different conformations will also have a serious impact on the quality of polymer products. Therefore, when testing the flow field distribution of the fluid in the tube, it is also necessary to test the distribution of fluid viscosity in each tail tube. At present, there is no good method to effectively test the flow field distribution between different tail tubes.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The first purpose of the present invention is to provide a method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline. The method provides a finite element simulation method that can be used to test the flow field distribution state of the fluid in different tail pipes, comprehensively considers the influence of the fluid properties and pipeline parameters, and more realistically reflects the flow field distribution of the fluid in the pipeline.

[0005] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: A method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline, the detection method comprising the following steps: Construct multi-tail pipe pipeline model and multi-tail pipe fluid model; After the construction is completed, the multi-tail pipe pipeline model and the multi-tail pipe fluid model are assembled to form a model pipeline; Then, loads and boundary conditions are created and introduced into the model pipeline, and the flow field distribution of the fluid in the model pipeline is calculated to obtain the detection result; Wherein, the steps of assembling are: Importing the multi-tail pipe pipeline model and the multi-tail pipe fluid model, and creating face-to-face parallel constraints on the multi-tail pipe pipeline model and the multi-tail pipe fluid model; After the creation is completed, a reference point is randomly selected on the multi-tail pipe fluid model and the multi-tail pipe pipeline model, and then the two reference points are translated so as to overlap, and the multi-tail pipe fluid model is embedded in the multi-tail pipe pipeline model after rotation.

[0006] In the present invention, the multi-tail pipe pipeline model and the multi-tail pipe fluid model are established by any software with modeling function that is currently available or developed in the future, wherein the number of tail pipes of a multi-tail pipe pipeline of the present invention can be 2-n. The present invention establishes a model pipeline through finite element modeling, introduces the model pipeline into a simulated fluid environment, and establishes a simulated flow field model by simulating a real fluid environment. Loads and boundary conditions are created for the model according to actual working conditions or preset working conditions, so that the model pipeline can obtain accurate detection results in a scene close to the real one, and then the simulation result information such as flow velocity and flow direction of the fluid in the multi-tail pipe pipeline at different times and different positions can be obtained, and the flow field state of the fluid in the multi-tail pipe pipeline at different times and different positions can be judged according to the simulation result information, and then the stability and uniformity of the fluid flow field can be judged, and an accurate detection method is provided for wet spinning processes such as polyester fiber, polyamide fiber, polyacrylonitrile fiber, polyimide fiber, nylon fiber, polystyrene fiber, sodium alginate fiber, etc. using non-Newtonian fluid as the stock solution, as well as polymer processing processes such as co-extrusion of multi-layer film, multi-layer pipe extrusion, production, spraying, and melt extrusion of composite materials.

[0007] Preferably, as a further specific implementation manner, the reference point is respectively the center point of the top circular surface of the first tail pipe of the multi-tail pipe fluid model and the multi-tail pipe pipeline model.

[0008] In the assembly process of the present invention, the multi-tail pipe pipeline model and the multi-tail pipe fluid model are imported into the assembly module at a specific assembly module in the software, and then a reference surface is arbitrarily selected on the multi-tail pipe pipeline model, and a corresponding reference surface is selected on the multi-tail pipe fluid model based on the reference surface, wherein the reference surfaces are all a horizontal cross-section formed by the tops of multiple tail pipes in the multi-tail pipe pipeline model, and a parallel constraint is established between the two surfaces so that the two reference surfaces remain parallel, and the mutual movement of the multi-tail pipe pipeline model and the multi-tail pipe fluid model in one direction is restricted, so that the pipeline model and the fluid model can only perform a 180° or 360° rotation operation at the same time and cannot be rotated separately, and then a standard surface is created so that the multi-tail pipe pipeline model and the multi-tail pipe fluid model are consistent in any direction, so that the original three-dimensional assembly becomes a two-dimensional assembly, which simplifies the assembly process and makes the assembly effect more accurate, so that the multi-tail pipe fluid model is better embedded in the multi-tail pipe pipeline model.

[0009] Preferably, as a further specific implementation, the step of creating a plane-to-plane parallel constraint is: selecting a reference plane on the multi-tail pipe pipeline model and the multi-tail pipe fluid model respectively, and establishing a parallel constraint between the two planes.

[0010] Preferably, as a further specific implementation manner, the reference planes are selected from cross sections of tops of multiple tail pipes of the multi-tail pipe pipeline model and the multi-tail pipe fluid model.

[0011] After the face-to-face parallel constraint is created, a reference point is first randomly selected on the multi-tail pipe pipeline model, and then a corresponding reference point is selected on the multi-tail pipe fluid model based on the reference point. When the reference points are all center points of the top cross section of the first tail pipe in the arrangement of multiple tail pipes, the assembly achieved is simpler, and the two reference points can be better accurately overlapped after translation. Then, after rotation, the multi-tail pipe fluid model can be better embedded in the multi-tail pipe pipeline model.

[0012] Preferably, as a further specific implementation, the load mainly includes concentrated force, bending moment, pressure, surface load, body force and gravity; the boundary conditions include symmetry, antisymmetry, displacement, angle of rotation, velocity, angular velocity and acceleration.

[0013] Preferably, as a further specific implementation, the load is pressure and gravity, and the boundary conditions are velocity and displacement.

[0014] In the present invention, the selection of loads and boundary conditions is very important. This is because the setting of loads and boundary conditions is a simplification of the actual working conditions. Inaccurate settings will affect the accuracy of the test results to a certain extent. When the loads are pressure and gravity, the flow of the fluid in the pipeline is powered by them, which can more realistically reflect the migration of the fluid based on the simplification of the on-site working conditions, and the boundary conditions can well simulate the actual working conditions of the processing technology, such as limiting the movement of the pipeline to avoid affecting the distribution of the fluid due to displacement of the pipeline.

[0015] Preferably, as a further specific implementation, the step of constructing a multi-tail pipe pipeline model is: Drawing an initial pipeline model: first drawing a basic figure, and then rotating or stretching the basic figure 360 ​​degrees to obtain the initial pipeline model; Drawing a curved pipe structure: drawing a sweep path at one end of the initial pipe model, then intercepting a surface at the top of the initial pipe model, and sweeping the surface along the sweep path to obtain the curved pipe structure of the initial pipe model; After the curved pipe structure is drawn, the multi-tail pipe pipeline model is obtained.

[0016] Preferably, as a further specific implementation, the step of constructing the multi-tail pipe fluid model is: Drawing the initial pipeline model: introducing the Euler domain, first drawing the basic graphics, and then rotating or stretching the basic graphics 360 degrees to obtain the initial pipeline model; Drawing a curved pipe structure: drawing a sweep path at one end of the initial pipe model, then intercepting a surface at the top of the initial pipe model, and sweeping the surface along the sweep path to obtain the curved pipe structure of the initial pipe model; After the curved pipe structure is drawn, the multi-tail pipe fluid model is obtained.

[0017] In the above scheme, a pipeline model is constructed by simulation, and the pipeline model is placed in a simulation environment to simulate the real fluid environment to calculate the distribution of the fluid flow field in the pipeline, so as to obtain the simulation result information such as the flow velocity and flow direction of the fluid in the pipeline at different times and positions. Subsequently, the flow field state of the fluid in the container at different times and positions is judged according to the simulation detection result information, and then the stability and uniformity of the fluid flow field are judged. When it is found through the test results that the fluid flow field distribution in the multi-tail pipe pipeline is uneven, the model structure and other parameters can be modified to repeat the simulation test until a stable flow field that meets the requirements of the process is found, thereby providing reliable modification suggestions for the actual production process and saving a lot of trial and error time and economic costs for the polymer processing technology.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline. The method provides a finite element simulation method that can be used to test the flow field distribution state of the fluid in different tail pipes, comprehensively considers the influence of the fluid properties and pipeline parameters, and more realistically reflects the flow field distribution of the fluid in the pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] By reading the detailed description of the preferred embodiment below, various other advantages and benefits will become clear to those of ordinary skill in the art. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment and are not considered to be limitations of the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings.

[0020] Figure 1 A schematic flow chart of a method for detecting flow field distribution of a fluid in a multi-tail pipe pipeline of the present invention; Figure 2 The multi-tail pipe pipeline model with five tail pipes drawn in Example 1; Figure 3 The multi-tail pipe pipeline model with eight tail pipes drawn in Example 1; Figure 4 The multi-tail pipe flow model with five tail pipes drawn in Example 1; Figure 5 The multi-tail pipe flow model with eight tail pipes drawn in Example 1; Figure 6The flow field distribution state of each tail pipe having five tail pipes measured in Example 1; Figure 7 : is the flow field distribution state of each tail pipe having eight tail pipes measured in Example 1; Figure 8 The flow field distribution state of each tail pipe having five tail pipes measured after reducing the viscosity in Example 1; Fig. 9 This is the flow field distribution state of each tail pipe having eight tail pipes measured after reducing the viscosity in Example 1. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In order to more clearly explain the technical solution of the present invention, it is described in the form of specific embodiments below.

[0023] Example 1 As mentioned above, in order to detect the flow field distribution effect between multiple tail tubes in the spinning process, the relevant technology usually needs to complete the construction of the production line before conducting relevant tests. However, since it is extremely difficult to adjust and modify the production line after it is built, the trial and error cost of this detection method is extremely high, the experimental cycle is long, and the viscosity distribution at different positions in the pipeline at different times cannot be dynamically obtained during the detection process. In view of this, the present invention provides a method for detecting the flow field distribution of fluid in a multi-tail tube pipeline. The method constructs a simulated pipeline and places the pipeline in a simulated fluid environment for detection, so that the flow field state and viscosity distribution of the fluid in the pipeline at different times and different positions can be accurately obtained, and then the stability and uniformity of the fluid flow field can be judged.

[0024] According to one aspect of an embodiment of the present invention, a method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline is provided, and the reliability detection method can be implemented based on any existing or future developed finite element analysis software. The finite element analysis software includes but is not limited to Hyperworks, Abaqus, Soildworks, etc.

[0025] Figure 1 A schematic flow chart showing a method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline of the present invention is shown as follows: Figure 1As shown, the specific detection steps of a method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline of the present invention are as follows: First, construct a multi-tail pipe pipeline model and a multi-tail pipe fluid model; the initial pipeline model can be constructed according to GBT 20801-2020 (Pressure Piping Specification-Industrial Piping), or it can be modified by the user entering custom parameters. The pipeline model can be obtained through modeling software such as Hyperworks, Abaqus, Soildworks and other modeling software.

[0026] Optionally, the multi-tail pipe pipeline model and the multi-tail pipe fluid model can be established by any existing or future developed software with modeling function. The number of tail pipes of a multi-tail pipe pipeline of the present invention can be 2-n, and the structural parameters of the pipeline can be controlled by input parameters. For example, in this embodiment, Abaqus can be used to establish a multi-tail pipe pipeline model and a multi-tail pipe fluid model, and a pipeline cross-section diagram is drawn using a sketch tool in the Abaqus software. In an embodiment of the present invention, a rectangle of the pipeline cross-section diagram is drawn using a sketch tool, and then the initial pipeline model is obtained by rotating 360° with the length of the rectangle as the central axis, wherein Figure 2 The pipeline model with five tail pipes drawn in this embodiment, Figure 3 The pipeline model with eight tail pipes drawn in this embodiment; Then, based on the initial pipeline model, a cross-sectional view of the tail pipe is drawn on the software sketch according to the input structural parameters, and then the cross-sectional view is stretched to obtain a plurality of tail pipes at the top of the initial pipeline model; Draw a sweep path in the software sketch to supplement the elbow structure of a section of the initial pipeline model. The radius of the sweep path can be obtained according to the pipeline size and the GB / T5632-2008 (flared combined elbow pipe joint) standard. The front elbow structure can be drawn by sweeping the pipeline interface along the sweep path. The multi-tail pipe pipeline model is completed by sweeping. In Abaqus software, the fluid region modeling is carried out in accordance with the method of multi-tail pipe model, the Euler domain is introduced, and the multi-tail pipe fluid model is constructed by using power law model, Carreau Yasuda model, Cross model, Herschel-Bulkley model, rheological curve and state equation model.

[0027] in Figure 4 FIG. 1 is a fluid region with five tail pipes and a fluid model constructed using a power law model drawn in an embodiment of the present invention. Figure 5 A fluid region with eight tail pipes and a fluid model constructed using a power law model are drawn in an embodiment of the present invention; After the model is established, the material properties of the multi-tail pipe and the fluid filled in the multi-tail pipe can be input into the property module in the Abaqus software. Optionally, the material properties of the pipe can be density, Poisson's ratio, elastic modulus, yield strength, etc.; the material properties of the fluid can be viscosity, density, state equation parameters, specific heat capacity, thermal conductivity, mass diffusion coefficient, etc.; Specifically, in the embodiment of the present invention, the Abaqus software is used to input the property parameters of the pipeline and the fluid in the property module, wherein the property parameters of the pipeline are density, elastic modulus and Poisson's ratio, and the property parameters of the fluid are density, state equation parameters and viscosity; the parameters of common materials can be queried in the "Handbook of Common Material Parameters for Finite Element Analysis"; Then, the multi-tail pipe pipeline model and the multi-tail pipe fluid model are assembled. In the assembly module of the Abaqus software, the multi-tail pipe pipeline model and the multi-tail pipe fluid model are firstly imported into the assembly module respectively, and a reference surface is selected on the multi-tail pipe pipeline model. In an embodiment of the present invention, the reference surface on the multi-tail pipe pipeline model is selected as a horizontal section formed by the tops of multiple tail pipes. Then, a corresponding reference surface is selected on the multi-tail pipe fluid model, and a parallel constraint is established between the two surfaces so that the two reference surfaces remain parallel, thereby limiting the mutual movement of the multi-tail pipe pipeline model and the multi-tail pipe fluid model in one direction, so that the multi-tail pipe pipeline model and the multi-tail pipe fluid model can only perform a 180° or 360° rotation operation at the same time and cannot perform a separate rotation operation, thereby creating a standard surface, so that the multi-tail pipe pipeline model and the multi-tail pipe fluid model are consistent in any direction, so that the original three-dimensional assembly becomes a two-dimensional assembly, simplifying the assembly process while making the assembly effect more accurate, so that the multi-tail pipe fluid model is better embedded in the multi-tail pipe pipeline model; After the face-to-face parallel constraint is created, a reference point is randomly selected on the multi-tail pipe pipeline model and the multi-tail pipe fluid model. Specifically, in the embodiment of the present invention, the reference point is selected as the center point of the circular cross section of the top of the first tail pipe among the multi-tail pipes evenly arranged on the multi-tail pipe pipeline model. Then, a corresponding reference point is selected on the multi-tail pipe fluid model. Then, a translation tool is used in the Abaqus software to make the two reference points coincide. After the coincidence, the rotation tool can be used to embed the multi-tail pipe fluid model into the multi-tail pipe pipeline model. Then, loads and boundary conditions were created in Abaqus software to simulate the real fluid environment and establish a simulation flow field model; Optionally, the load may be concentrated force, bending moment, pressure, surface load, body force and gravity, etc.; the boundary condition may be symmetry, antisymmetry, displacement, angle, velocity, angular velocity and acceleration, etc.; specifically, in this embodiment, the load is pressure and gravity, and the boundary condition is velocity and displacement; through such a setting, the simulated pipeline is set to be completely fixed, that is, the movement of the pipeline is restricted, Then, the calculation task is submitted in the job module of the Abaqus software. After the calculation is completed, the detection result of the simulated pipeline can be obtained in the visualization module. In the visualization module, the simulation result information such as the flow velocity and flow direction of the fluid in the pipeline at different times and positions can be obtained. In this embodiment, the specific initial detection results of each tail pipe of the model with five tail pipes and the model with eight tail pipes are shown as follows: Figure 6 and Figure 7 As shown, the same range is selected to calculate the average flow velocity in the tail pipe, and the results are shown in Table 1 and Table 2: Table 1 Average flow velocity in different tail pipes of five tail pipe models

[0028] Table 2 Average flow velocity in different tail pipes of eight tail pipe models

[0029] Through the above test results, it can be clearly observed that the average flow velocity in the two tail pipes at both ends is significantly greater than that in other tail pipes in both pipelines, and the model with eight tail pipes has a more uneven distribution of flow velocity between different tail pipes than the model with five tail pipes, and the uniformity of the flow field in the tail pipes is worse. This is because the increase in the number of tail pipes enhances the disturbance of the flow field between different tail pipes; the average outflow velocity of the two tail pipes is significantly greater than that of other tail pipes, which will cause more solution to be sprayed out from the two tail pipes, resulting in the phenomenon of fiber doubling during the drawing process, causing the fiber to not be completely solidified inside, and the phenomenon of broken wires during the drawing process; at the same time, the flow field disturbance in the tail pipe is large, which will also have a certain impact on the quality of the silk thread. The analysis results are accurate and consistent with the actual observation phenomenon, indicating that the test results are accurate and have a certain reference value, further verifying the effectiveness of the fluid simulation model.

[0030] Optionally, in the subsequent operation process, the model parameters can be modified to provide guidance for the spinning process design. When it is found that the flow field in the pipeline is unevenly distributed after detection, the model structure and other parameters can be modified to repeat the simulation test until a stable flow field that meets the requirements of the process is found, thereby providing reliable modification suggestions for the actual production process, saving a lot of trial and error time and economic costs for the spinning process; In this embodiment, through a series of simulations, it is found that reducing the viscosity of the fluid can significantly enhance the flow field stability of the fluid. When the viscosity of the fluid is reduced by one order of magnitude, the flow field stability is significantly improved. The specific test results of the improved tail pipe flow fields of the model with five tail pipes and the model with eight tail pipes are as follows: Figure 8 and Fig. 9 The average flow rate of each tail pipe is shown in Table 3 and Table 4. Compared with Table 1, Table 2, Figure 6 and Figure 7 It can be clearly observed that the velocity difference between the tail pipes is significantly reduced, and the uniformity of the flow field is greatly improved; Table 3 Average flow velocity in different tail pipes of five tail pipe models

[0031] Table 4 Average flow velocity in different tail pipes of eight tail pipe models

[0032] From the above data, it can be known that the detection method for the flow field distribution of the fluid in a multi-tail pipe pipeline provided by the present invention constructs a pipeline model by simulation, and places the pipeline model in a simulation environment to simulate the real fluid environment to calculate the flow field distribution of the fluid in the pipeline, thereby obtaining the simulation result information such as the flow velocity and flow direction of the fluid in the pipeline at different times and positions, and then judges the flow field state of the fluid in the container at different times and positions according to the simulation detection result information, and then judges the stability and uniformity of the fluid flow field. Subsequently, the initial model parameters can be modified to perform repeated detection during the detection process of the present invention, so as to obtain pipeline parameters with better effects, and the detection cycle is short, the cost is low, and the detection results are accurate, providing reliable modification suggestions for the actual production process.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting the flow field distribution of a fluid in a multi-tail pipe pipeline, characterized in that: The detection method comprises the following steps: Construct multi-tail pipe pipeline model and multi-tail pipe fluid model; After the construction is completed, the multi-tail pipe pipeline model and the multi-tail pipe fluid model are assembled to form a model pipeline; Then, loads and boundary conditions are created and introduced into the model pipeline, and the flow field distribution of the fluid in the model pipeline is calculated to obtain the detection result; Wherein, the steps of assembling are: Importing the multi-tail pipe pipeline model and the multi-tail pipe fluid model, and creating face-to-face parallel constraints on the multi-tail pipe pipeline model and the multi-tail pipe fluid model; After the creation is completed, a reference point is randomly selected on the multi-tail pipe fluid model and the multi-tail pipe pipeline model, and then the two reference points are translated so as to overlap, and the multi-tail pipe fluid model is embedded in the multi-tail pipe pipeline model after rotation.

2. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 1, characterized in that: The reference points are respectively the center points of the top circular surfaces of the first tail pipes of the multi-tail pipe fluid model and the multi-tail pipe pipeline model.

3. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 1, characterized in that: The step of creating a face-to-face parallel constraint is: selecting a reference surface on the multi-tail pipe pipeline model and the multi-tail pipe fluid model respectively, and establishing a parallel constraint between the two surfaces.

4. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 3, characterized in that: The reference surfaces are selected from cross sections of tops of multiple tail pipes of the multi-tail pipe pipeline model and the multi-tail pipe fluid model.

5. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 1, characterized in that: The loads mainly include concentrated force, bending moment, pressure, surface load, body force and gravity; the boundary conditions include symmetry, antisymmetry, displacement, rotation angle, velocity, angular velocity and acceleration.

6. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 5, characterized in that: The loads are pressure and gravity, and the boundary conditions are velocity and displacement.

7. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 1, characterized in that: The steps of constructing the multi-tail pipe pipeline model are: Drawing an initial pipeline model: first drawing a basic figure, and then rotating or stretching the basic figure 360 ​​degrees to obtain the initial pipeline model; Drawing a curved pipe structure: drawing a sweep path at one end of the initial pipe model, then intercepting a surface at the top of the initial pipe model, and sweeping the surface along the sweep path to obtain the curved pipe structure of the initial pipe model; After the curved pipe structure is drawn, the multi-tail pipe pipeline model is obtained.

8. The method for detecting the flow field distribution of fluid in a multi-tail pipe pipeline according to claim 1, characterized in that: The steps of constructing the multi-tail pipe fluid model are: Drawing the initial pipeline model: introducing the Euler domain, first drawing the basic graphics, and then rotating or stretching the basic graphics 360 degrees to obtain the initial pipeline model; Drawing a curved pipe structure: drawing a sweep path at one end of the initial pipe model, then intercepting a surface at the top of the initial pipe model, and sweeping the surface along the sweep path to obtain the curved pipe structure of the initial pipe model; After the curved pipe structure is drawn, the multi-tail pipe fluid model is obtained.

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