Watershed Sub-block Grid Division Method and Device

Abstract

The present application discloses a method and device for dividing a basin into blocks and meshes, which relates to the technical field of aircraft design. The method includes: constructing a complete solid model according to design requirements; wherein, the complete solid model includes a gap basin solid model, an aircraft aerodynamic shape solid model and an outer basin solid model; setting surface mesh division parameters, and performing surface mesh division on the complete solid model based on the surface mesh division parameters to obtain a surface mesh model; setting a boundary layer in the outer basin of the surface mesh model, setting the division parameters of the inner mesh of the boundary layer to perform volume mesh division, and generating a volume mesh model; importing the volume mesh model into fluid dynamics software, setting basin connectivity and flow conditions to perform simulation, and obtaining an aerodynamic data set. The problem that the division of unstructured meshes in the prior art has high requirements for the experience of technicians and easily leads to completely untrustworthy calculation results is solved. The accuracy and reliability of aerodynamic calculation results can be improved.

Description

Technical Field

[0001] This application relates to the technical field of aircraft design, and particularly to a method and device for dividing a domain into blocks and generating grids. Background Art

[0002] Computational grids are mainly divided into structured grids and unstructured grids. Structured grids have a relatively small error when compared with the results of wind tunnel tests in practical applications, and thus are widely used. They can meet the design requirements of flight control laws and flight requirements, and have high reliability. However, structured grids take a long time to generate grids, and there are limitations in generating grids for complex shapes. Therefore, unstructured grids were proposed in the 1960s. Utilizing the powerful computing power of computers, a large amount of work can be completed by computers, which has obvious advantages compared with structured grids and can save a large amount of time for designers. Moreover, unstructured grids have good adaptability to models and can better generate grids for regions with complex shapes.

[0003] However, unstructured grids have very high requirements for the experience of technicians. Improper grid generation can lead to completely untrustworthy calculation results. Especially for the aerodynamic shape at gaps such as control surfaces, when using conventional unstructured grids for generation, there are two situations when setting the boundary layer. One is that at gaps such as control surfaces, the boundary layer is compressed, and the grid distribution is severely uneven (as shown in Figure 3 ); the other is that the total height of the boundary layer is insufficient (as shown in Figure 4 ). After a large number of repeated calculations and comparative analyses, it is shown that improper setting of the boundary layer has a significant impact on the aerodynamic calculation results, leading to completely untrustworthy calculation results. Summary of the Invention

[0004] Embodiments of this application provide a method and device for dividing a domain into blocks and generating grids, which solve the problem in the prior art that the generation of unstructured grids has high requirements for the experience of technicians and is likely to lead to completely untrustworthy calculation results.

[0005] In a first aspect, embodiments of this application provide a method for dividing a domain into blocks and generating grids, including: constructing a complete solid model according to design requirements; wherein, the complete solid model includes a gap domain solid model, an airframe aerodynamic shape solid model, and an outer domain solid model; setting surface grid generation parameters, and generating a surface grid model by performing surface grid generation on the complete solid model based on the surface grid generation parameters; setting a boundary layer in the outer domain of the surface grid model, setting the grid generation parameters in the boundary layer to perform volume grid generation, and generating a volume grid model; importing the volume grid model into fluid dynamics software, and setting domain connectivity and flow conditions to perform simulation, so as to obtain an aerodynamic data set.

[0006] In combination with the first aspect, in a possible implementation manner, the constructing of the complete entity model according to the design requirements includes: based on the design requirements, constructing an airframe aerodynamic shape entity model of the aerodynamic shape; determining the boundary of the external flow field according to the size and shape of the airframe aerodynamic shape entity model, and constructing an external flow field entity model of the external flow field; identifying the gap between the main wing surface and the rudder surface in the airframe aerodynamic shape entity model, and if the gap meets the preset gap condition, constructing the gap flow field entity model; merging the gap flow field entity model, the airframe aerodynamic shape entity model and the external flow field entity model, and performing a common node operation on the overlapping surfaces of the merged models to obtain the complete entity model.

[0007] In combination with the first aspect, in a possible implementation manner, the setting of the surface mesh division parameters includes: setting the minimum size of the surface mesh so that it satisfies a first ratio with the minimum size of the airframe aerodynamic shape entity model; setting the maximum size of the external flow field entity model so that its ratio with the wingspan of the airframe satisfies a second ratio, and setting the maximum size of the airframe aerodynamic shape entity model as the mean aerodynamic chord length; setting the growth rate of the surface mesh of the airframe aerodynamic shape entity model and the gap flow field entity model as a preset threshold, and the number of grid cells corresponding to the minimum size in the airframe aerodynamic shape entity model and the gap flow field entity model is not less than the preset number of grids.

[0008] In combination with the first aspect, in a possible implementation manner, after the surface mesh division of the complete entity model based on the surface mesh division parameters, it further includes: if the divided surface mesh does not meet the quality requirements, iteratively moving the grid nodes in the surface mesh until the surface mesh meets the quality requirements; and / or, marking the grid nodes in the surface mesh that do not meet the quality requirements, and merging the adjacent grids involved in the grid nodes that do not meet the quality requirements; and / or, deleting the grid nodes in the surface mesh that do not meet the quality requirements, and re-performing surface mesh division on the area of the deleted grid nodes.

[0009] In combination with the first aspect, in a possible implementation manner, the setting of the division parameters of the grids within the boundary layer for volume mesh division includes: determining the height of the first layer of grids within the boundary layer and the height of other grids according to the mean aerodynamic chord length; setting the growth rate of the grids within the boundary layer and the number of layers of the boundary layer; determining the sizes of the volume grids within the boundary layer according to the growth rate of the grids within the boundary layer, the height of the first layer of grids, and the number of layers of the boundary layer to perform volume mesh division.

[0010] In combination with the first aspect, in a possible implementation manner, determining the height of the first layer of grids in the boundary layer and the heights of other grids according to the mean aerodynamic chord length includes: setting the height of the first layer of grids in the boundary layer based on the mean aerodynamic chord length; determining the heights of the other grids according to the mean aerodynamic chord length and the Reynolds number.

[0011] In combination with the first aspect, in a possible implementation manner, after generating the volume mesh model, it further includes: obtaining the mesh skewness of the volume meshes in the volume mesh model; evaluating whether the mesh skewness meets a preset skewness.

[0012] In a second aspect, an embodiment of the present application provides a watershed block mesh generation device, including: a construction module for constructing a complete solid model according to design requirements; wherein, the complete solid model includes a gap watershed solid model, an airframe aerodynamic shape solid model, and an outer watershed solid model; a surface mesh generation module for setting surface mesh generation parameters and performing surface mesh generation on the complete solid model based on the surface mesh generation parameters to obtain a surface mesh model; a volume mesh generation module for setting a boundary layer in the outer watershed of the surface mesh model, setting the division parameters of the grids in the boundary layer to perform volume mesh generation, and generating a volume mesh model; a simulation module for importing the volume mesh model into a computational fluid dynamics software, setting the watershed connection and flow conditions for simulation to obtain an aerodynamic data set.

[0013] In a third aspect, an embodiment of the present application provides a device, the device includes: a processor; a memory for storing processor-executable instructions; when the processor executes the executable instructions, it implements the method as described in the first aspect or any possible implementation manner of the first aspect.

[0014] In a fourth aspect, an embodiment of the present application provides a non-volatile computer-readable storage medium, the non-volatile computer-readable storage medium includes computer programs or instructions for storage, and when the computer programs or instructions are executed, the method as described in the first aspect or any possible implementation manner of the first aspect is implemented.

[0015] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0016] In the embodiment of the present application, a gap flow domain entity model is separately established for the gap. By setting a boundary layer for the outer flow domain and generating a volume mesh, problems such as boundary layer compression and insufficient total boundary layer height at the gap are avoided. Further, in the subsequent fluid dynamics calculation process, by setting the flow domain connection, it can be ensured that the connected flow domains become a whole flow domain for calculation. This effectively solves the problem that the division of unstructured grids in the prior art has high requirements for the experience of technicians and is likely to lead to completely untrustworthy calculation results. Furthermore, the accuracy and reliability of the aerodynamic calculation results are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments of the present application or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a flowchart of a method for dividing a flow domain block grid provided by an embodiment of the present application;

[0019] Figure 2 It is a schematic structural diagram of a device for dividing a flow domain block grid provided by an embodiment of the present application;

[0020] Figure 3 It is a schematic diagram showing boundary layer compression during unstructured grid division provided by an embodiment of the present application;

[0021] Figure 4 It is a schematic diagram showing insufficient total boundary layer height during unstructured grid division provided by an embodiment of the present application;

[0022] Figure 5 It is an example diagram of an aircraft aerodynamic outer shape entity model provided by an embodiment of the present application;

[0023] Figure 6 It is an example diagram of an outer flow domain entity model provided by an embodiment of the present application;

[0024] Figure 7 It is an example diagram of a gap flow domain entity model provided by an embodiment of the present application;

[0025] Figure 8 It is an example diagram of a complete entity model provided by an embodiment of the present application;

[0026] Figure 9 It is an example diagram of a surface mesh without performing co - node operation provided by an embodiment of the present application;

[0027] Figure 10 It is an example diagram of a surface mesh model provided by an embodiment of the present application;

[0028] Figure 11 An example diagram of the mesh for structured mesh generation provided by an embodiment of the present application;

[0029] Figure 12 An example diagram of the mesh divided by the method of the present application provided by an embodiment of the present application;

[0030] Figure 13 An example diagram of filling the gap between the rudder surface and the main wing surface provided by an embodiment of the present application;

[0031] Figure 14 Provided by an embodiment of the present application Figure 11 Flow chart of the mesh generation method;

[0032] Figure 15 Provided by an embodiment of the present application Figure 11 Local flow chart of the mesh generation method;

[0033] Figure 16 Provided by an embodiment of the present application Figure 12 Flow chart of the mesh generation method;

[0034] Figure 17 Provided by an embodiment of the present application Figure 12 Local flow chart of the mesh generation method;

[0035] Figure 18 Provided by an embodiment of the present application Figure 3 Flow chart of the mesh generation method;

[0036] Figure 19 Provided by an embodiment of the present application Figure 3 Local flow chart of the mesh generation method;

[0037] Figure 20 Provided by an embodiment of the present application Figure 4 Flow chart of the mesh generation method;

[0038] Figure 21 Provided by an embodiment of the present application Figure 4 Local flow chart of the mesh generation method;

[0039] Figure 22 Provided by an embodiment of the present application Figure 13 Flow chart of the mesh generation method. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0041] The following explanations are made for some of the technologies involved in the embodiments of the present application to facilitate understanding. It should be considered that they are merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, some descriptions of well-known functions and structures are omitted in the following description.

[0042] Figure 1 is a flowchart of a method for dividing a basin into blocks and meshing, including steps 101 to 104. Among them, Figure 1 This is only one execution order shown in the embodiments of the present application and does not represent the only execution order of the method for dividing a basin into blocks and meshing. In the case where the final result can be achieved, Figure 1 the steps shown can be executed in parallel or reversed.

[0043] Step 101: Construct a complete solid model according to the design requirements. Among them, the complete solid model includes a gap basin solid model, an airframe aerodynamic shape solid model, and an outer basin solid model. In the embodiments of the present application, based on the design requirements, an airframe aerodynamic shape solid model of the aerodynamic shape is constructed. The boundary of the outer basin is determined according to the size and shape of the airframe aerodynamic shape solid model, and the outer basin solid model of the outer basin is constructed. Identify the gap between the main wing surface and the rudder surface in the airframe aerodynamic shape solid model. If the gap meets the preset gap condition, a gap basin solid model is constructed. The gap basin solid model, the airframe aerodynamic shape solid model, and the outer basin solid model are merged, and the common node operation is performed on the overlapping surfaces of the merged models to obtain a complete solid model.

[0044] Specifically, in the present application, a CFD (Computational Fluid Dynamics) calculation model pre-processing software (such as a computer-aided design modeling software such as CAD) is used to construct an airframe aerodynamic shape solid model (including components such as the main wing, tail wing, and fuselage) according to the design requirements respectively, and save it, as Figure 5 shown is the airframe aerodynamic shape solid model provided by the present application.

[0045] According to the size and shape of the aerodynamic configuration, determine the boundary of the outer flow domain (i.e., the flow domain outside the flow domain corresponding to the gap flow domain solid model). The boundary of the outer flow domain should be large enough to contain all key flow characteristics and reduce the influence of the boundary on the simulation results. Use CAD (Computer-Aided Design) software to construct a three-dimensional solid model of the outer flow domain containing the aerodynamic configuration, that is, the outer flow domain solid model, and ensure seamless docking between the outer flow domain solid model and the airframe aerodynamic configuration solid model, such as Figure 6 The outer flow domain solid model provided by the present application is shown.

[0046] Identify the gap between the control surface and the main wing surface in the airframe aerodynamic configuration solid model. When the gap meets the preset gap condition, use CAD software to construct a three-dimensional solid model of the gap, that is, the gap flow domain solid model, and ensure that the size and shape of the gap flow domain solid model conform to the actual situation, such as Figure 7 The gap flow domain solid model provided by the present application is shown. Here, the preset gap condition is exemplarily set to be less than or equal to 0.005c, where c represents the mean aerodynamic chord length.

[0047] Import the gap flow domain solid model, the airframe aerodynamic configuration solid model, and the outer flow domain solid model into CAD software to ensure the correct positioning of each model in space. Then merge these three models, identify all overlapping surfaces in the merged model, and use the co-node or stitching function of CAD software to convert these overlapping surfaces into co-node surfaces for co-node operations to obtain a complete solid model. The nodes on the co-node surfaces will share the same coordinates, thereby ensuring the continuity of the complete solid model in flow simulation, such as Figure 8 The complete solid model provided by the present application is shown. If no co-node operation is performed on the merged model, the grids at the overlapping surfaces will not be co-noded, as Figure 9 shown, and it will be impossible to generate volume grids.

[0048] Step 102: Set the surface mesh division parameters, and perform surface mesh division on the complete solid model based on the surface mesh division parameters to obtain a surface mesh model. In the embodiment of the present application, setting the surface mesh division parameters includes: setting the minimum size of the surface mesh to satisfy a first ratio with the minimum size of the airframe aerodynamic configuration solid model. Set the maximum size of the outer flow domain solid model to satisfy a second ratio with the wingspan of the airframe, and set the maximum size of the airframe aerodynamic configuration solid model to the mean aerodynamic chord length. Set the growth rate of the surface meshes of the airframe aerodynamic configuration solid model and the gap flow domain solid model to a preset threshold, and the number of grid cells corresponding to the minimum size in the airframe aerodynamic configuration solid model and the gap flow domain solid model is not less than the preset number of grids.

[0049] Exemplarily, the first ratio is 1 / 3, that is, the minimum size of the surface mesh is set to 1 / 3 of the minimum size of the physical model of the airframe aerodynamic shape. The second ratio is 10, that is, the maximum size of the outer flow domain physical model is set to 10 times the wingspan of the airframe. The preset threshold is 1.2, that is, the growth rate of the surface meshes of the physical model of the airframe aerodynamic shape and the gap flow domain physical model is exemplarily set to 1.2, and the preset number of meshes is exemplarily set to 3, that is, the number of mesh elements corresponding to the minimum size in the physical model of the airframe aerodynamic shape and the gap flow domain physical model is not less than 3.

[0050] Based on the above-set surface mesh division parameters, perform surface mesh division on the complete physical model to obtain a surface mesh model, as Figure 10 shown. In addition, evaluate whether the divided surface mesh model meets the quality requirements. If the divided surface mesh does not meet the quality requirements, iteratively move the mesh nodes in the surface mesh until the surface mesh meets the quality requirements. And / or, mark the mesh nodes in the surface mesh that do not meet the quality requirements, and merge the adjacent meshes involved in the mesh nodes that do not meet the quality requirements. And / or, delete the mesh nodes in the surface mesh that do not meet the quality requirements, and re-perform surface mesh division on the area where the deleted mesh nodes are located. Among them, the quality requirements are exemplarily set such that the skewness of the surface mesh is less than or equal to 0.65.

[0051] Specifically, evaluating the quality of the surface mesh model includes indicators such as mesh size, shape, skewness, etc. Use a gradient-based optimization algorithm to iteratively adjust the positions of the mesh nodes multiple times to improve the shape and size of the surface mesh. After each iteration, re-evaluate the quality of the surface mesh model to ensure that each adjustment is effective until the surface mesh model meets the quality requirements.

[0052] Or, mark the mesh nodes of the mesh elements in the surface mesh model with a skewness greater than 0.65. For adjacent mesh elements with similar shapes and high skewness, merge them into a larger mesh element, and re-evaluate the quality of the merged surface mesh model.

[0053] Or, for mesh nodes that cannot improve the quality by moving the mesh nodes or merging the mesh elements, they can be deleted. After deletion, use an appropriate mesh generation method (such as re-meshing, adaptive mesh generation, etc.) to re-generate the meshes in these areas.

[0054] Step 103: Set a boundary layer in the outer flow domain of the surface mesh model, set the division parameters of the mesh in the boundary layer to perform volume mesh division, and generate a volume mesh model. In the embodiment of the present application, after obtaining the surface mesh model, a suitable boundary layer is set specifically for the outer flow domain.

[0055] In the embodiments of the present application, the height of the first layer of grids in the boundary layer and the height of other grids are determined according to the mean aerodynamic chord length. The growth rate of the grids in the boundary layer and the number of layers of the boundary layer are set. The sizes of the volume grids in the boundary layer are determined according to the growth rate of the grids in the boundary layer, the height of the first layer of grids, and the number of layers of the boundary layer, so as to perform volume grid division.

[0056] Specifically, the height of the first layer of grids in the boundary layer is set based on the mean aerodynamic chord length; the height of other grids is determined according to the mean aerodynamic chord length and the Reynolds number. Exemplarily, the height of the first layer of grids in the boundary layer is set to c×10 -5 . Those skilled in the art should be aware that the height of the first layer of grids in the boundary layer here should be small enough to capture the flow details in the boundary layer, but not too small to avoid over-dense grids and increased computational burden.

[0057] The calculation formula for the height of other grids is as follows:

[0058] .

[0059] In the formula, represents the height of other grids, represents the mean aerodynamic chord length, and Re represents the Reynolds number.

[0060] The growth rate of the grids in the boundary layer is exemplarily set to [1.2, 2]. The growth rate determines how the sizes of the grids in the boundary layer increase as the distance from the object surface increases. A smaller growth rate means that the grids are denser in the boundary layer and can capture the flow details more accurately. The number of layers of the boundary layer is exemplarily set to 16 to ensure sufficient resolution in the boundary layer to capture the flow characteristics.

[0061] Using the boundary layer grid generation tool in the CFD software, the volume grids of the boundary layer are set according to the above-determined division parameters (the height of the first layer of grids, the growth rate, and the number of layers). Ensure that the volume grids of the boundary layer are smoothly transitioned with the surface grids to avoid excessive gradients or gaps at the grid junctions.

[0062] In addition, the grid skewness of the volume grids in the volume grid model is obtained. Evaluate whether the grid skewness meets the preset skewness. The preset skewness here is exemplarily set to 0.95.

[0063] Step 104: Import the volume mesh model into the computational fluid dynamics (CFD) software, set the domain connectivity and flow conditions for simulation, and obtain the aerodynamic dataset. In the embodiment of the present application, the generated volume mesh model is imported into the CFD software, the interfaces between the connected domains are found and selected, and the types of these interfaces are set to Interior (internal, indicating that the interface allows the fluid to pass through freely, making the connected domains equivalent to a single overall domain). This means that these interfaces are where the fluid can pass through freely, thus ensuring that the connected domains are treated as a single overall domain. Set the flow conditions such as pressure, temperature, and velocity, and set the angle of attack, sideslip angle of the aircraft aerodynamic external shape solid model, as well as other boundary conditions and initial conditions, and finally perform the simulation.

[0064] After the calculation is completed, extract the aerodynamic forces and moments that vary with the angle of attack / sideslip angle, analyze their aerodynamic performance, and form an aerodynamic dataset for use in the design of the flight control law and the performance / handling and stability analysis of the aircraft.

[0065] The present application uses a domain-blocking unstructured grid generation method to solve the problems of insufficient boundary layer height or boundary layer compression at the gaps in existing unstructured grid generation. As Figure 11 shown, it is the grid of structured grid generation. As Figure 12 shown, it is the grid generated by the method of the present application. The grids of the boundary layers at the gaps between the control surface and the main wing surface are basically the same for both.

[0066] If the gap between the control surface and the main wing surface is filled, it can ensure that the boundary layer is properly set during unstructured grid generation. As Figure 13 shown, but it will make the flow field at the gap inconsistent with the actual situation, resulting in errors in the calculation results such as an overestimated lift and an underestimated drag.

[0067] As Figure 14 and Figure 15 shown are the streamline diagrams of the grid generation method in Figure 11 (structured grid). The height of its boundary layer is properly set, and boundary layer compression occurs at the gap between the control surface and the main wing. As Figure 16 and Figure 17 shown are the streamline diagrams of the grid generation method in Figure 12 (the domain-blocking unstructured grid of the present application). As Figure 18 and Figure 19 shown are the streamline diagrams of the grid generation method in Figure 3 (unstructured grid with boundary layer compression). The streamlines are significantly curved at the gap, affecting the aerodynamic calculation results. As Figure 20 and Figure 21 shown are the streamline diagrams of the grid generation method in Figure 4Streamline diagram of the grid generation method in (unstructured grid, total height of the boundary layer is insufficient), where the height of the boundary layer is less than the calculation result. As Figure 22 shown in Figure 13 the calculation result of the grid generation method in (unstructured grid, gap filled), there is no streamline at the gap in the streamline diagram of the filled gap, which does not conform to the actual flow.

[0068] As shown below, Tables 1, 3, and 5 are the aerodynamic calculation results of the same aircraft's aerodynamic shape using different grid generation methods (except for different grid generation methods, other calculation settings are exactly the same). Table 1 shows the drag coefficients at angles of attack of 0°, 2°, and 4°. Table 3 shows the lift coefficients at angles of attack of 0°, 2°, and 4°. Table 5 shows the pitching moment coefficients at angles of attack of 0°, 2°, and 4°. Calculate the Figure 12 , Figure 3 , Figure 4 , Figure 13 relative errors between the calculation results of the unstructured grid shown in Figure 11 and the structured grid shown in

[0069] The calculation method of the relative error is as follows:

[0070] Relative error = (unstructured grid - structured grid) / structured grid, and the calculation results are shown in Tables 2, 4, and 6 respectively.

[0071] Table 1 Drag Coefficient Table

[0072]

[0073] Table 2 Relative Error Table of Drag Coefficient

[0074]

[0075] Table 3 Lift Coefficient Table

[0076]

[0077] Table 4 Relative Error Table of Lift Coefficient

[0078]

[0079] Table 5 Pitching Moment Table

[0080]

[0081] Table 6 Relative Error Table of Pitching Moment

[0082]

[0083] Based on the above analysis, the relative error between the calculation results of the basin-block unstructured grid of this application and the calculation results of the structured grid is small, with high reliability, meeting the requirements of engineering design.

[0084] Although this application provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative labor. The step sequence listed in this embodiment is only one way among the execution sequences of numerous steps and does not represent the only execution sequence. When the actual device or client product is executed, it can be executed in the method sequence shown in this embodiment or the accompanying drawings or executed in parallel (for example, in an environment of parallel processors or multi-threaded processing).

[0085] As Figure 2 shown, the embodiment of this application also provides a device 200 for basin-block grid division. The device includes: a construction module 201, a surface grid division module 202, a volume grid division module 203, and a simulation module 204, which are specifically as follows.

[0086] The construction module 201 is used to construct a complete entity model according to design requirements. Among them, the complete entity model includes a gap basin entity model, an airframe aerodynamic shape entity model, and an outer basin entity model.

[0087] The surface grid division module 202 is used to set surface grid division parameters and perform surface grid division on the complete entity model based on the surface grid division parameters to obtain a surface grid model.

[0088] The volume grid division module 203 is used to set an attached layer in the outer basin of the surface grid model, set the division parameters of the grids in the attached layer to perform volume grid division, and generate a volume grid model.

[0089] The simulation module 204 is used to import the volume grid model into a fluid dynamics software, set basin connectivity and flow conditions to perform simulation, and obtain an aerodynamic data set.

[0090] Some modules in the device described in this application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform specific tasks or implement specific abstract data types. This application can also be practiced in a distributed computing environment, where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0091] The devices or modules described in the above application embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. For the convenience of description, when describing the above devices, they are divided into various modules according to functions and described separately. When implementing the application embodiments, the functions of each module can be implemented in the same or multiple software and / or hardware. Of course, the module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0092] The methods, devices or modules described in this application can be implemented in the form of computer-readable program codes. The controller can be implemented in any appropriate manner. For example, the controller can take the form of, for example, a microprocessor or a processor, and a computer-readable medium storing computer-readable program codes (such as software or firmware) executable by the (micro)processor, logic gates, switches, application specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program codes, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers to achieve the same function. Therefore, such a controller can be considered a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or structures within the hardware component.

[0093] The embodiments of this application also provide a device, which includes: a processor; a memory for storing executable instructions of the processor; when the processor executes the executable instructions, the method described in the embodiments of this application is implemented.

[0094] The embodiments of this application also provide a non-volatile computer-readable storage medium, on which a computer program or instructions are stored. When the computer program or instructions are executed, the method described in the embodiments of this application is implemented.

[0095] In addition, in each embodiment of the present invention, the functional modules can be integrated into one processing module, or each module can exist alone, or two or more modules can be integrated into one module.

[0096] The above storage medium includes, but is not limited to, random access memory (English: Random Access Memory; abbreviation: RAM), read-only memory (English: Read-Only Memory; abbreviation: ROM), cache (English: Cache), hard disk drive (English: Hard Disk Drive; abbreviation: HDD), or memory card (English: Memory Card). The memory can be used to store computer program instructions.

[0097] From the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary hardware. Based on such an understanding, the technical solution of the present application, in essence or the part that contributes to the prior art, can be embodied in the form of a software product, or can also be reflected in the implementation process of data migration. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the present application.

[0098] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. All or part of the present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, mobile communication terminals, multi-processor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and so on.

[0099] The above embodiments are only used to illustrate the technical solution of the present application, rather than limiting the present application; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solution described in the foregoing embodiments, or perform equivalent substitution on some or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the present application.

Claims

1. A method for dividing a watershed into blocks and grids, characterized in that: include: Constructing a complete entity model according to design requirements; wherein the complete entity model includes a gap flow domain entity model, an airframe aerodynamic shape entity model and an outer flow domain entity model; merging the gap flow domain entity model, the airframe aerodynamic shape entity model and the outer flow domain entity model, and performing a common node operation on the overlapping surfaces of the merged models to obtain the complete entity model; Setting surface meshing parameters, performing surface meshing on the complete solid model based on the surface meshing parameters to obtain a surface mesh model; wherein, setting the surface meshing parameters includes: setting a minimum size of the surface mesh so that its ratio to the minimum size of the airframe aerodynamic shape solid model satisfies a first ratio; setting a maximum size of the outer flow domain solid model so that its ratio to the airframe wingspan satisfies a second ratio, and setting the maximum size of the airframe aerodynamic shape solid model to the average aerodynamic chord length; setting the growth rate of the surface mesh of the airframe aerodynamic shape solid model and the gap flow domain solid model to a preset threshold, and the number of mesh units corresponding to the minimum size in the airframe aerodynamic shape solid model and the gap flow domain solid model is not less than a preset number of meshes; Setting a boundary layer in the outer flow domain of the surface grid model, setting the grid division parameters in the boundary layer to perform volume grid division, and generating a volume grid model, including: determining the height of the first layer of grids in the boundary layer and the heights of other grids according to the average aerodynamic chord length; Wherein, determining the height of the first layer of grids and the heights of other grids in the boundary layer according to the average aerodynamic chord length includes: setting the height of the first layer of grids in the boundary layer based on the average aerodynamic chord length; determining the heights of other grids according to the average aerodynamic chord length and the Reynolds number; The volume grid model is imported into fluid dynamics software, and flow domain connectivity and flow conditions are set for simulation to obtain an aerodynamic data set.

2. The method according to claim 1, characterized in that The construction of a complete solid model according to design requirements also includes: Based on the design requirements, construct a solid model of the aerodynamic shape of the fuselage; Determine the boundary of the outer flow domain according to the size and shape of the aerodynamic shape entity model of the aircraft body, and construct the outer flow domain entity model of the outer flow domain; The gap between the main wing surface and the control surface in the aerodynamic shape entity model of the aircraft body is identified, and if the gap meets the preset gap condition, the gap flow domain entity model is constructed.

3. The method according to claim 1, characterized in that After performing surface meshing on the complete solid model based on the surface meshing parameters, the method further includes: If the divided surface mesh does not meet the quality requirements, the mesh nodes in the surface mesh are iteratively moved until the surface mesh meets the quality requirements; and / or, marking mesh nodes in the surface mesh that do not meet the quality requirements, and merging adjacent meshes involved in the mesh nodes that do not meet the quality requirements; And / or, mesh nodes that do not meet quality requirements in the surface mesh are deleted, and the surface mesh is re-divided in the area where the mesh nodes are deleted.

4. The method according to claim 1, characterized in that The step of setting the mesh partitioning parameters in the boundary layer to perform volume mesh partitioning includes: Determine the height of the first layer of grids and the heights of other grids in the boundary layer according to the average aerodynamic chord length; Setting the growth rate of the grid in the boundary layer and the number of layers of the boundary layer; The size of each volume grid in the boundary layer is determined according to the growth rate of the grid in the boundary layer, the height of the first layer of grids and the number of layers of the boundary layer, so as to perform volume grid division.

5. The method according to claim 1, characterized in that After the volume mesh model is generated, the method further includes: Get the mesh skewness of the volume mesh in the volume mesh model; Evaluate whether the grid skewness satisfies a preset skewness.

6. A watershed block grid division device, characterized in that: include: A construction module is used to construct a complete entity model according to design requirements; wherein the complete entity model includes a gap flow domain entity model, an airframe aerodynamic shape entity model and an outer flow domain entity model; the gap flow domain entity model, the airframe aerodynamic shape entity model and the outer flow domain entity model are merged, and a common node operation is performed on the overlapping surfaces of the merged models to obtain the complete entity model; A surface mesh division module, used for setting surface mesh division parameters, performing surface mesh division on the complete solid model based on the surface mesh division parameters to obtain a surface mesh model; wherein the setting of the surface mesh division parameters includes: setting the minimum size of the surface mesh so that its ratio with the minimum size of the airframe aerodynamic shape solid model satisfies a first ratio; setting the maximum size of the outer flow domain solid model so that its ratio with the airframe wingspan satisfies a second ratio, and setting the maximum size of the airframe aerodynamic shape solid model to the average aerodynamic chord length; setting the growth rate of the surface mesh of the airframe aerodynamic shape solid model and the gap flow domain solid model to a preset threshold, and the number of mesh units corresponding to the minimum size in the airframe aerodynamic shape solid model and the gap flow domain solid model is not less than the preset number of meshes; A volume mesh division module is used to set a boundary layer in the outer flow domain of the surface mesh model, set the mesh division parameters in the boundary layer to perform volume mesh division, and generate a volume mesh model, including: determining the height of the first layer of meshes in the boundary layer and the heights of other meshes according to the average aerodynamic chord length; Wherein, determining the height of the first layer of grids and the heights of other grids in the boundary layer according to the average aerodynamic chord length includes: setting the height of the first layer of grids in the boundary layer based on the average aerodynamic chord length; determining the heights of other grids according to the average aerodynamic chord length and the Reynolds number; The simulation module is used to import the volume grid model into the fluid dynamics software, set the flow domain connectivity and flow conditions for simulation, and obtain the aerodynamic data set.

7. A device for executing a watershed block grid partitioning method, characterized in that: include: processor; a memory for storing processor-executable instructions; When the processor executes the executable instructions, the method according to any one of claims 1 to 5 is implemented.

8. A non-volatile computer-readable storage medium, characterized in that: The device comprises a computer program or an instruction for storing the computer program or the instruction, which, when executed, enables the method according to any one of claims 1 to 5 to be implemented.

Images