Method of data transfer between fluid domain and solid domain in fluid-solid coupling simulation

Abstract

The present invention discloses a method for data transmission between a fluid domain and a solid domain during a fluid-solid coupling simulation process, and belongs to the technical field of fluid-solid coupling simulation of impeller machinery. The method comprises: obtaining data information on the known data side of the fluid-solid coupling interface to form a known data set; obtaining data information on the unknown data side of the fluid-solid coupling interface to form an unknown data set; selecting a target node in the unknown data set; finding the three nodes 1, 2, and 3 closest to the target node in the known data set; determining the distance d from the target node to the plane where nodes 1, 2, and 3 are located, and if d is less than or equal to a preset threshold, calculating the target node data; selecting the next target node in the unknown data set, and repeating the above steps until all nodes in the unknown data set obtain corresponding data information. The present invention can realize accurate data transmission at any grid scale, and does not significantly increase the time of data mapping.

Description

Technical Field

[0001] The invention relates to the technical field of fluid-solid coupling simulation of turbomachinery, and in particular to a method for data transmission between a fluid domain and a solid domain in a fluid-solid coupling simulation process. Background Art

[0002] In the process of fluid-solid coupling simulation, accurate data transfer between the fluid interface and the solid interface is a key link. However, in the process of fluid-solid coupling simulation, the meshes of the fluid domain and the solid domain are usually generated separately, which leads to mismatch of mesh nodes on both sides of the interface between the fluid domain and the solid domain. Data transfer is required, which requires the use of data mapping / interpolation technology. The quality of the data mapping method directly affects the fidelity of data transfer, and thus affects the accuracy of the simulation results.

[0003] In the prior art, taking the transfer of fluid domain data to solid domain data as an example, the common practice is: search for the fluid node closest to the target solid node at the fluid-solid interface, and then assign the value of the fluid node to the target solid node. A further improvement method is: search for several fluid nodes closest to the target solid node, then calculate the corresponding shape function, and finally weight the data of the target solid node.

[0004] The data required in the above method include: the mesh node coordinates and corresponding data of the fluid domain at the interface, and the mesh node coordinates of the solid domain at the interface. Generally, the above method can obtain good interpolation accuracy. However, in the field of turbomachinery, when the thickness of the blade is small and the mesh scales of the fluid domain and the solid domain at the interface are quite different (such as Figure 1 As shown in the figure), the nearest node found at this time may be located on the other side wall of the blade (as shown in the figure). Figure 2 As shown in the figure, it is difficult to obtain good interpolation accuracy, or even get wrong results.

[0005] It should be noted that in the field of turbomachinery, especially on the surface of blades or other thin-walled structures, data transfer between fluid domains and solid domains has its own particularity: because some structures are very thin, when the grid scale is not enough, it is very likely that the grid node closest to the target grid node is located on the surface on the other side of the structure, which will cause erroneous data to be transferred to the target node. Reducing the grid scale and increasing the number of grids will significantly increase the computational cost. Therefore, there is currently no good solution for how to effectively and accurately transfer data between fluid-solid grids on the surface of thin blades / thin-walled structures. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for data transfer between fluid domain and solid domain in fluid-solid coupling simulation process, which can effectively and accurately transfer data between fluid-solid grids on the surface of thin blades / thin-wall structures.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A method for data transmission between a fluid domain and a solid domain during a fluid-solid coupling simulation process, comprising:

[0009] Step 1: Acquire the data information on the known data side of the fluid-solid coupling interface to form a known data set;

[0010] Step 2: Obtain data information on the unknown data side of the fluid-solid coupling interface to form an unknown data set;

[0011] Step 3: Select a target node in the unknown data set;

[0012] Step 4: Find the node closest to the target node in the known data set through calculation as node 1, and record its node number, coordinates and data;

[0013] Step 5: Find all units including node 1 as unit set 1 according to the node number of node 1 and its unit number information;

[0014] Step 6: Find the node closest to the target node other than node 1 among all the nodes included in unit set 1 as node 2, and record its node number, coordinates and data;

[0015] Step 7: Find all units including node 1 and node 2 as unit set 2 according to the node numbers of node 1 and node 2 and their unit number information;

[0016] Step 8: Find the node closest to the target node other than node 1 and node 2 among all nodes included in unit set 2 as node 3, and record its node number, coordinates and data;

[0017] Step 9: Determine the distance d from the target node to the plane where nodes 1, 2, and 3 are located. If d is greater than the preset threshold, remove node 1 from the known data set and re-execute steps 4-9; otherwise, execute step 10;

[0018] Step 10: Calculate the target node data using the data of nodes 1, 2, and 3 in the known data set or the cells where nodes 1, 2, and 3 are located;

[0019] Step 11: Recover all data in the known data set;

[0020] Step 12: Select the next target node in the unknown data set and repeat steps 4-11 until all nodes in the unknown data set obtain corresponding data information.

[0021] Furthermore, the step 9 includes: if the number of removed nodes reaches a preset number, increasing the preset threshold, restoring all data in the known data set, and re-executing steps 4-9.

[0022] Furthermore, the step 10 comprises:

[0023] Step 101: determining a shape function according to data of a target node and nodes 1, 2, and 3, or according to node data in a unit where the target node and nodes 1, 2, and 3 are located;

[0024] Step 102: Calculate the data of the target node based on the shape function and nodes 1, 2, 3, or based on the shape function and the node data in the unit where nodes 1, 2, 3 are located.

[0025] Furthermore, in step 102, the data of the target node:

[0026]

[0027] Among them, P i is the parameter to be sought, N j and P j are the shape function and parameters of the jth node in the selected nodes, respectively, and m is the number of selected nodes.

[0028] Furthermore, the method further comprises:

[0029] Step 13: Check whether the data transfer result is accurate. If it is accurate, go to step 14;

[0030] Step 14: Output the unknown data set.

[0031] Furthermore, the step 13 includes: if it is inaccurate, reducing the preset threshold and returning to step 3.

[0032] Furthermore, in step 13, the method for verifying whether the data transfer result is accurate is:

[0033] Use node numbers, coordinates and unit numbers to draw the obtained data of unknown data into a cloud map, and compare it with the cloud map of the data of known data to verify whether the obtained data is accurate;

[0034] Alternatively, the node set on the unknown data side, including the data in the unknown data set obtained in step 12, is used as the known data set, and the other side is used as the unknown data set. The data recalculated on the other side is obtained through the above steps 1-12, and then compared with the known data on the other side. If the difference between the two meets the accuracy requirements, the data transfer result is accurate.

[0035] The present invention has the following beneficial effects:

[0036] If the existing data mapping technology wants to achieve accurate data transfer between the fluid domain and the solid domain on the surface of thin blades / thin-walled structures, it is necessary to ensure that there is sufficient grid density on both sides, that is, the grid scale must be sufficiently small relative to the thickness scale of the blade, which will undoubtedly significantly increase the calculation cost of the simulation. Compared with the prior art, the method of data transfer between the fluid domain and the solid domain during the fluid-solid coupling simulation of the present invention can effectively and accurately transfer data between the fluid-solid grids on the surface of thin blades / thin-walled structures, and can achieve accurate data transfer at any grid scale without significantly increasing the data mapping time (compared with the increase in calculation time caused by increasing the number of grids, the data mapping time is very short). BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of meshes of a fluid domain and a solid domain on a fluid-solid interface surface of an example blade in the prior art;

[0038] Figure 2 A schematic diagram of possible problems in applying the interpolation technology in the prior art to thin blades / thin-wall structures;

[0039] Figure 3 It is a flow chart of the method for data transmission between the fluid domain and the solid domain in the fluid-solid coupling simulation process of the present invention;

[0040] Figure 4 A flow chart of an embodiment of a method for data transmission between a fluid domain and a solid domain during a fluid-solid coupling simulation process of the present invention;

[0041] Figure 5 This is a comparison diagram of interpolation results for thin blade surface data between the present invention and the prior art. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0043] The present invention provides a method for data transmission between a fluid domain and a solid domain in a fluid-solid coupling simulation process. Figure 3 As shown, including:

[0044] Step 1: Obtain the data information on the known data side of the fluid-solid coupling interface (data mapping interface) to form a known data set;

[0045] Step 2: Obtain data information on the unknown data side of the fluid-solid coupling interface to form an unknown data set;

[0046] Step 3: Select a target node in the unknown data set;

[0047] Step 4: Find the node closest to the target node in the known data set through calculation as node 1, and record its node number, coordinates and data;

[0048] Step 5: Find all units including node 1 as unit set 1 according to the node number of node 1 and its unit number information;

[0049] Step 6: Find the node closest to the target node other than node 1 among all the nodes included in unit set 1 as node 2, and record its node number, coordinates and data;

[0050] Step 7: Find all units including node 1 and node 2 as unit set 2 according to the node numbers of node 1 and node 2 and their unit number information;

[0051] Step 8: Find the node closest to the target node other than node 1 and node 2 among all nodes included in unit set 2 as node 3, and record its node number, coordinates and data;

[0052] Step 9: Determine the distance d from the target node to the plane where nodes 1, 2, and 3 are located. If d is greater than the preset threshold, remove node 1 from the known data set and re-execute steps 4-9; otherwise, execute step 10;

[0053] In this step, by reasonably selecting the preset threshold, it can be effectively ensured that the target node and the selected node are located on the same side of the blade, thereby ensuring the accuracy of data transmission; the preset threshold can be set to 10% of the maximum thickness of the thin blade / thin-wall structure. This value depends on the situation, and the appropriate threshold can also be found through multiple attempts.

[0054] As an optional embodiment, step 9 may include:

[0055] If the number of removed nodes reaches a preset number, the preset threshold is increased, all data in the known data set is restored, and steps 4-9 are re-executed.

[0056] In this embodiment, the preset number can be flexibly set as needed, for example, it can be set to the number of all nodes in the known data set. However, to improve computing efficiency, it is preferably smaller than the number of all nodes in the known data set, for example, it can be set to 8, 9, 10, etc.

[0057] Step 10: Calculate the target node data using the data of nodes 1, 2, and 3 in the known data set or the cells where nodes 1, 2, and 3 are located;

[0058] As an optional embodiment, this step 10 preferably includes:

[0059] Step 101: determining a shape function according to data of a target node and nodes 1, 2, and 3, or according to node data in a unit where the target node and nodes 1, 2, and 3 are located;

[0060] If the data of nodes 1, 2, and 3 are used, the shape function can be expressed as follows:

[0061]

[0062] Wherein, N1, N2 and N3 are the shape functions of nodes 1, 2 and 3 respectively, S1 is the area of ​​the triangle formed by the projection point i' of the target node i in the plane formed by nodes 1, 2, 3 and nodes 2 and 3, S2 is the area of ​​the triangle formed by the projection point i' of the target node i in the plane formed by nodes 1, 2, 3 and nodes 1 and 3, S3 is the area of ​​the triangle formed by the projection point i' of the target node i in the plane formed by nodes 1, 2, 3 and nodes 1 and 2, S=S1+S2+S3.

[0063] If the node data in the unit where nodes 1, 2, and 3 are located is used (it can be all the nodes in the unit, that is, the 8 nodes in the following formula, or some of the nodes in the unit), the shape function can be expressed as:

[0064]

[0065] Among them, s, t, and r are the local coordinates of the target node i in the unit. For any point in the structural unit or on the unit surface, -1≤r, s, t≤1.

[0066] Step 102: Calculate the data of the target node based on the shape function and nodes 1, 2, 3, or based on the shape function and the node data in the unit where nodes 1, 2, 3 are located.

[0067] In this step, the calculation formula for the data of target node i can be as follows:

[0068]

[0069] Among them, P i is the parameter to be sought, N j and P j are the shape function and parameters (known) of the jth node in the selected nodes, and m is the number of selected nodes.

[0070] Step 11: Recover all data in the known data set;

[0071] In this step, the removed node data is restored to the known data set.

[0072] Step 12: Select the next target node in the unknown data set and repeat steps 4-11 until all nodes in the unknown data set obtain corresponding data information.

[0073] To improve the accuracy of data transmission, as an optional embodiment, the above method may further include:

[0074] Step 13: Check whether the data transfer result is accurate. If it is accurate, go to step 14;

[0075] Step 14: Output the unknown data set.

[0076] Preferably, the above step 13 includes:

[0077] If it is inaccurate, reduce the preset threshold and return to step 3.

[0078] Furthermore, in the above step 13, the verification method for whether the data transmission result is accurate can be the following two verification methods:

[0079] One verification method is: using the node number, coordinates and unit number to draw the data obtained from the unknown data set into a cloud map, and compare it with the cloud map of the data in the known data set to verify whether the obtained data is accurate;

[0080] Another verification method is: use the node set on the unknown data side, including the data in the unknown data set obtained in step 12, as the known data set, and the other side as the unknown data set, obtain the recalculated data on the other side through the method described in the above steps 1-12, and then compare it with the known data on the other side. If the difference between the two meets the accuracy requirements, the data transfer result is accurate.

[0081] Compared with the prior art, the method of data transfer between the fluid domain and the solid domain during the fluid-solid coupling simulation of the present invention can effectively and accurately transfer data between the fluid-solid grids on the surface of thin blades / thin-wall structures, can achieve accurate data transfer at any grid scale, and does not significantly increase the data mapping time (compared with the increase in calculation time caused by increasing the number of grids, the data mapping time is very short).

[0082] The method for data transmission between the fluid domain and the solid domain during the fluid-solid coupling simulation of the present invention is described in detail below with a specific example.

[0083] like Figure 4 As shown, taking the transmission of fluid domain pressure data to solid domain as an example, the present invention provides a method for transmitting data at the interface between the fluid domain and the solid domain of a thin blade during a fluid-solid coupling simulation, comprising the following steps:

[0084] Step 1: Extract the data on one side of the fluid domain (known data side), including node number, coordinate, pressure and unit number, to form a known data set;

[0085] Step 2: Extract the node coordinates on one side of the solid domain (the unknown data side) to form an unknown data set;

[0086] Step 3: Select a target node i from the nodes on the solid domain side of the fluid-structure interaction interface;

[0087] Step 4: Calculate the distance from the target node i to each node in the fluid domain side data set, find the fluid node closest to the target node i (referred to as node 1), and record its node number, coordinates, and pressure;

[0088] Step 5: Find all fluid units including node 1 (referred to as unit set 1) according to the numbering information of node 1 and the unit numbering information;

[0089] Step 6: Find the node closest to the target node i (called node 2) among all the fluid nodes contained in unit set 1 except node 1, and record its node number, coordinates and pressure;

[0090] Step 7: Find all fluid units including node 1 and node 2 (referred to as unit set 2) according to the numbering information of node 1 and node 2 and combined with the unit numbering information;

[0091] Step 8: Find the node closest to the target node i (called node 3) among all the fluid nodes included in unit set 2 except node 1 and node 2, and record its node number, coordinates and pressure;

[0092] Step 9: Determine the distance d from the target node to the plane where the fluid nodes 1, 2, and 3 are located. If d is greater than the preset threshold, remove node 1 from the fluid domain side data set and re-execute steps 4-9; otherwise, execute step 10; if the distance obtained by traversing all nodes in the fluid domain data set (in fact, traversal is not necessary here, and a limit can be set to be more efficient, such as when the number of removed nodes reaches 10) is still greater than the preset threshold, then re-select a larger threshold, restore all data in the known data set, and re-execute steps 4-9;

[0093] In this step, the preset threshold is used to determine whether the target solid node is located on the plane formed by the selected fluid nodes. In this embodiment, the initial threshold can be selected as 10% of the maximum thickness of the blade tip (this value depends on the situation, and a suitable threshold can be found through multiple attempts, and is not limited to 10% of the maximum thickness of the blade tip).

[0094] Step 10: The pressure of the target node i is obtained by weighted calculation using the pressures of the fluid nodes 1, 2, and 3. This step 10 specifically includes the following steps:

[0095] Step 101: According to the coordinates of the target node i and nodes 1, 2, and 3, the shape function is obtained as follows:

[0096]

[0097] Among them, l i It represents the length of the line segment between nodes i and j.

[0098] Step 102: Calculate the pressure of target node i based on the shape function and the pressure results of nodes 1, 2, and 3:

[0099]

[0100] Among them, P i is the pressure of target node i, N j and P j are the shape functions and pressures (known) corresponding to nodes 1, 2, and 3 respectively.

[0101] Step 11: Restore all data in the fluid domain dataset;

[0102] Step 12: Select the next target node on the solid domain side and repeat steps 4-11 until the pressure of all nodes on the solid domain side is obtained;

[0103] Step 13: Check whether the obtained solid domain node pressure is accurate. If there is distortion, reselect a smaller preset threshold and return to step 3;

[0104] In this step, one verification method is to use the node number, coordinate and element number to draw the obtained solid domain pressure as shown in Figure 5 The cloud map shown is compared with the fluid domain pressure cloud map to verify whether the obtained pressure is accurate; another more accurate verification method is: take the node set on the fluid domain side of the fluid-solid coupling interface as the unknown data set, and take the node set on the solid domain side, including the obtained pressure data as the known data set, obtain the node pressure on the fluid domain side through the method described in the above steps 1-12, and then compare it with the known node pressure on the fluid domain side. If the difference between the obtained fluid domain node pressure and the known fluid domain node pressure meets the accuracy requirement, it proves that the above-obtained solid domain side node pressure is accurate. The actual verification method includes but is not limited to the above two verification methods.

[0105] Step 14: Output the node pressure on the solid domain side.

[0106] Figure 5 is a comparison diagram of interpolation results of the present embodiment and the prior art for thin blade surface data, Figure 5 It can be clearly seen that the results of this embodiment are closer to known data results than the existing results.

[0107] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for data transmission between fluid domain and solid domain in fluid-solid coupling simulation of thin blades, characterized in that: include: Step 1: Acquire the data information on the known data side of the fluid-solid coupling interface to form a known data set; Step 2: Acquire data information on the unknown data side of the fluid-solid coupling interface to form an unknown data set, wherein the known data side is one of the fluid domain and the solid domain, and the unknown data side is the other of the fluid domain and the solid domain; Step 3: Select a target node in the unknown data set; Step 4: Find the node closest to the target node in the known data set through calculation as node 1, and record its node number, coordinates and pressure data; Step 5: Find all units including node 1 as unit set 1 according to the node number of node 1 and its unit number information; Step 6: Find the node closest to the target node other than node 1 among all nodes included in unit set 1 as node 2, and record its node number, coordinates and pressure data; Step 7: Find all units including node 1 and node 2 as unit set 2 according to the node numbers of node 1 and node 2 and their unit number information; Step 8: Find the node closest to the target node other than node 1 and node 2 among all nodes included in unit set 2 as node 3, and record its node number, coordinates and pressure data; Step 9: Determine the distance d from the target node to the plane where nodes 1, 2, and 3 are located. If d is greater than the preset threshold, remove node 1 from the known data set and re-execute steps 4-9; Otherwise, go to step 10; Step 10: Calculate the target node pressure data using the pressure data of nodes 1, 2, and 3 in the known data set or the unit where nodes 1, 2, and 3 are located; Step 11: Recover all data in the known data set; Step 12: Select the next target node in the unknown data set and repeat steps 4-11 until all nodes in the unknown data set obtain corresponding pressure data information.

2. The method according to claim 1, characterized in that The step 9 includes: if the number of removed nodes reaches a preset number, increasing the preset threshold, restoring all data in the known data set, and re-executing steps 4-9.

3. The method according to claim 1, characterized in that The step 10 comprises: Step 101: determining a shape function according to data of a target node and nodes 1, 2, and 3, or according to node data in a unit where the target node and nodes 1, 2, and 3 are located; Step 102: Calculate the pressure data of the target node based on the shape function and nodes 1, 2, 3, or based on the shape function and the node pressure data in the unit where nodes 1, 2, 3 are located.

4. The method according to claim 3, characterized in that In step 102, the pressure data of the target node: Among them, P i is the parameter to be sought, N j and P j are the shape function and parameters of the jth node in the selected nodes, respectively, and m is the number of selected nodes.

5. The method according to any one of claims 1 to 4, characterized in that: Also includes: Step 13: Check whether the pressure data transmission result is accurate. If it is accurate, go to step 14; Step 14: Output the pressure data of the unknown data set.

6. The method according to claim 5, characterized in that The step 13 includes: if it is inaccurate, reducing the preset threshold and returning to step 3.

7. The method according to claim 6, characterized in that In step 13, the method for verifying whether the pressure data transmission result is accurate is: The pressure data in the unknown data set is plotted into a cloud map using the node number, coordinates and unit number, and compared with the pressure data cloud map in the known data set to verify whether the pressure data is accurate; Alternatively, the node set on the unknown data side, including the pressure data in the unknown data set obtained in step 12, is used as the known data set, and the other side is used as the unknown data set. The recalculated pressure data of the other side is obtained through the above steps 1-12, and then compared with the known pressure data of the other side. If the difference between the two meets the accuracy requirements, the pressure data transmission result is accurate.

Images