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CN-122021425-A - STL format-based simulation method for wall-attached flow heat transfer of model in flow channel

CN122021425ACN 122021425 ACN122021425 ACN 122021425ACN-122021425-A

Abstract

The invention provides a simulation method for wall-attached flow heat transfer in a flow channel based on an STL (standard deviation) format model, which is suitable for simulating a core disturbance structure of a light high-efficiency heat exchanger in the aviation field and can accurately predict the flow heat exchange performance of an inserted disturbance structure in the flow channel under a turbulent flow working condition. The method comprises the steps of establishing a three-dimensional model in an STL format, dividing grids of the model serving as a disturbance structure in a flow channel, and calculating hydrodynamic simulation. The invention realizes the adherence treatment of the STL format model by developing a set of complete method from the three-dimensional model establishment to the CFD simulation, and effectively solves the problems of flow and heat transfer at the juncture of the wall surface and the disturbance structure. A set of method is provided for directly meshing the STL-format model, and compared with the traditional STL-format three-dimensional model converted into a solid format and wall surface seam-leaving operation, the method is more similar to the application under the actual working condition. An effective method is provided for promoting the wide application of the three-dimensional model in the STL format in the CFD field.

Inventors

  • ZHANG XIYAN

Assignees

  • 太原理工大学

Dates

Publication Date
20260512
Application Date
20260123

Claims (9)

  1. 1. The simulation method for the wall-attached flow heat transfer in the flow channel based on the STL format model is characterized by comprising the following steps: Step 1, acquiring a three-dimensional STL format file through a three-dimensional model in the STL format, and determining a simulation target, wherein the three-dimensional STL format file comprises all geometric information of the three-dimensional model; step 2, checking grid division defects in the three-dimensional STL format file and positioning defect points, repairing the defect points through geometric modeling until the defects which obstruct grid division and flow heat transfer calculation in the three-dimensional STL format file are not existed, and obtaining a first model; Step 3, deleting the boundary surface which is repeated with the inner wall surface of the runner in the first model, determining the position of the inlet and the outlet of the runner and the distance between the inlet and the outlet of the runner and the first model, establishing the complete inner wall surface of the runner, and ensuring that no defect point exists at the intersection of the inner wall surface of the runner and the first model; Step 4, dividing grids, namely, densifying the grid distribution of the contact parts between the model and the fluid and between the wall surface and the fluid, ensuring that boundary layer information is fully captured, and performing grid quality inspection after grid division is completed, so that the requirement of next calculation is met; And 5, importing the grid file obtained in the step 4 into a streaming heat transfer simulation system to perform simulation calculation.
  2. 2. The simulation method according to claim 1, wherein the geometric information in step 1 includes model porosity and triangular plate density.
  3. 3. The simulation method according to claim 1, wherein in step 3, topology optimization is performed after deleting the boundary surface overlapping the inner wall surface of the flow channel in the first model, so as to ensure that the inner wall surface of the flow channel and the model are closely attached.
  4. 4. The simulation method according to claim 1, wherein the distances between the positions of the inlet and the outlet of the flow channel and the corresponding end surfaces of the first model in the step 3 are all greater than 5 times of the characteristic length.
  5. 5. A simulation method according to claim 1, wherein when the flow passage section is rectangular, the characteristic length is a side length of the rectangle.
  6. 6. The simulation method according to claim 1, wherein in step 4, the mesh distribution of the contact portion between the densifying model and the fluid and between the wall surface and the fluid is specifically that the overall mesh size is maximum, the mesh of the inner wall surface of the flow channel is minor, and the mesh of the wall surface of the model is minimum.
  7. 7. The simulation method according to claim 6, wherein in step 4, the number of nodes at which the model and the inner wall surface of the flow path intersect increases when the mesh is densified.
  8. 8. The simulation method according to claim 1, wherein in step 4, the grid quality inspection and display are all above 0.3, which meets further calculation requirements.
  9. 9. The simulation method according to claim 1, wherein step 5, the grid file obtained in step 4 is imported into CFD software for processing, initial conditions and boundary conditions are set, a calculation model is selected, and data is collected after data convergence.

Description

STL format-based simulation method for wall-attached flow heat transfer of model in flow channel Technical Field The invention belongs to the field of computational fluid dynamics numerical simulation, and relates to a simulation method for wall-attached flow heat transfer in a flow channel based on an STL (standard test language) format model. Background The heat exchanger applied in the aviation field has the characteristics of light weight, high efficiency and the like, the application of the novel porous structure in the heat exchanger core is the development direction of future aviation heat exchangers, the cost of experimental research heat exchange structure is high, and the designability is limited. Therefore, researching the flow heat transfer performance of the heat exchanger core structure through a simulation method is a preferred path for saving cost and efficiently designing. Computational fluid dynamics (Computation Fluid Dynamics, CFD for short) is a discipline for researching the spatial physical characteristics of steady fluid motion and the space-time physical characteristics of unsteady fluid motion by solving a mathematical equation describing fluid motion through a computer by utilizing a numerical method, revealing the physical law of fluid motion. The STL file format is a three-dimensional graphics file format that serves rapid prototyping techniques. The STL file is composed of a plurality of triangle patch definitions, each triangle patch definition including three-dimensional coordinates of each of the triangle's points and normal vectors of the triangle patches. The three-dimensional model in the STL format has remarkable advantages in the field of additive manufacturing engineering, but the three-dimensional model in the STL format usually faces the problems of surface defects, incomplete bonding with a defined wall surface and the like when grid division software is imported. Aiming at the surface defect of the three-dimensional model in the STL format during grid division, a learner proposes to convert the STL format into an entity format such as STP and the like, so that the problem of the surface defect can be effectively solved, but a large amount of consumed calculation resources and differences between the entity model and an original STL model cannot be ignored, and aiming at the problem of incomplete fitting between the STL three-dimensional model and a defined wall surface, a certain gap is reserved between the defined wall surface and the three-dimensional model on the basis of using the STL format three-dimensional model, which can lead to the difference between heat transfer between the wall surface and the model and the actual working condition, and the difference between the damage of a disturbance structure and the actual working condition of a flow boundary layer. The simulation method for the wall-attached flow heat transfer in the flow channel based on the STL format model is significant. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a simulation method for adhering to flowing heat transfer in a runner based on a model in an STL format, which can effectively solve the defect problem of a three-dimensional model in the STL format in CFD simulation, and the simulation result of the novel method has better matching degree with the experimental result. The specific technical scheme of the invention is that the simulation method for the wall-attached flow heat transfer of the STL-format-based model in the flow channel comprises the following steps: Step 1, acquiring a three-dimensional STL format file through a three-dimensional model in the STL format, and determining a simulation target, wherein the three-dimensional STL format file comprises all geometric information of the three-dimensional model; step 2, checking grid division defects in the three-dimensional STL format file and positioning defect points, repairing the defect points through geometric modeling until the defects which obstruct grid division and flow heat transfer calculation in the three-dimensional STL format file are not existed, and obtaining a first model; And step 3, deleting the boundary surface which is repeated with the inner wall surface of the flow channel in the first model, wherein the step provides a foundation for realizing the wall-attached flow heat transfer of the model. Establishing a complete flow channel inner wall surface, and ensuring that no defect point exists at the intersection of the flow channel inner wall surface and the first model; Step 4, dividing grids, namely, densifying the grid distribution of the contact parts between the model and the fluid and between the wall surface and the fluid, ensuring that boundary layer information is fully captured, and performing grid quality inspection after grid division is completed, so that the requirement of next calculation is met; And 5, importing the grid file obtained in t