Duplex plunger pump flow field simulation method of spherical annular oil film

Abstract

The invention discloses a duplex plunger pump flow field simulation method for a spherical surface annular oil film, and the method employs the functions of volume extraction, mirroring and the like in SpaceClaim software to extract an internal drainage basin of a duplex plunger pump according to the working principle of the duplex axial plunger pump, greatly improves the model building efficiency, and improves the simulation precision of the duplex axial plunger pump. During modeling, a spherical annular oil film between a cylinder body and a valve plate is considered, ICEM software is proposed to carry out grid division on the spherical annular oil film, after a Nastran type grid file is exported, grid assembly is carried out in PumpLinx software, and reference is further provided for design and optimization of the plunger pump. The method comprises the following steps: 1, establishing a duplex plunger pump geometric model; step 2, establishing a duplex plunger pump drainage basin; step 3, carrying out mesh division on the drainage basin of the duplex plunger pump; step 4, establishing a drainage basin grid contact pair; 5, selecting a simulation model and setting corresponding parameters; 6, setting fluid simulation parameters; 7, simulation is started; and 8, analyzing a result.

Description

Technical Field

[0001] The invention belongs to the technical field of plunger pump modeling and CFD simulation, and in particular relates to a flow field simulation method of a double-connected plunger pump of a spherical annular oil film. Background Art

[0002] In excavators and concrete pump trucks, double-coupled plunger pumps are usually used as power units. The pressure oil is delivered to the hydraulic cylinder and hydraulic motor through a multi-way valve and a piping system. Under the condition of synchronous control of the speed of the double pumps, the double-coupled plunger pump can not only realize the separate operation of the double pumps and supply different hydraulic actuators with action respectively, but also under specific working conditions, the double pump confluence function enables the hydraulic actuators to complete the corresponding actions faster. Therefore, it is widely used in the field of construction machinery.

[0003] Currently, most of the research on the structural optimization and working characteristics of duplex axial piston pumps is done through experiments, which has the disadvantages of high cost, long cycle, and low simulation accuracy. In addition, most of the existing flow field simulation analyses of spherical flow distribution piston pumps ignore the spherical oil film, resulting in low simulation accuracy and the inability to obtain parameters on the oil film. The PumpLinx software can only generate planar oil film grids and cannot divide the spherical oil film. Therefore, it is necessary to consider the flow field simulation method of the duplex axial piston pump with spherical annular oil film to study the duplex axial piston pump. Summary of the invention

[0004] In view of the shortcomings of the above background technology, the purpose of the present invention is to provide a double-coupled plunger pump flow field simulation method for a spherical annular oil film. This method is based on the working principle of the double-coupled axial piston pump and uses the "volume extraction" and "mirror" functions in the SpaceClaim software to extract the internal flow domain of the double-coupled plunger pump, which greatly improves the efficiency of model establishment. The spherical annular oil film between the cylinder body and the distribution plate is considered during modeling, and it is proposed to use the ICEM software to mesh the spherical annular oil film. After exporting the Nastran type mesh file, the mesh is assembled in the PumpLinx software, and the flow domain between the bottom of the cylinder waist hole and the plunger is considered to be divided, and contact pairs are established to make the plunger pump flow field simulation more accurate, and further provide a reference for the design and optimization of the plunger pump.

[0005] To solve the above technical problems, the purpose of the present invention is achieved as follows:

[0006] A double-piston pump flow field simulation method for a spherical annular oil film comprises the following steps: step one: establishing a double-piston pump geometric model; step two: establishing a double-piston pump flow domain; step three: meshing the double-piston pump flow domain; step four: establishing flow domain mesh contact pairs; step five: selecting a simulation model and setting corresponding parameters; step six: setting fluid simulation parameters; step seven: starting simulation; and step eight: analyzing results.

[0007] On the basis of the above scheme and as a preferred scheme of the above scheme: the geometric model of the double plunger pump in step 1 is composed of a front pump, a rear pump and a shared intermediate body, wherein the intermediate body shares an oil suction port, and the two oil discharge ports are used separately, the rotating shafts of the front pump and the rear pump are connected by a coupling to meet the synchronous control of the speed of the two pumps, and the front pump and the rear pump have separate variable mechanisms, which can realize the separate operation and confluence operation of the two pumps;

[0008] The structures of the two pumps are identical and mirror-symmetrical. Each pump consists of a distribution plate, a cylinder body, a plunger, a sliding shoe and a swash plate. Each pump has nine plungers. When the parts are assembled, the inclination angle of the swash plate is set to 0°, and a plunger hole of the cylinder body is facing the inner dead center of the distribution plate. When the geometric model is established, the origin is located at the intersection of the cross section in the intermediate body and the rotation axis, which is convenient for the subsequent extraction of the plunger flow domain and the assembly of the spherical annular oil film. The rotation axis is located on the Z axis of the three-dimensional coordinate system, and it rotates from the positive semi-axis of the X axis to the positive semi-axis of the Y axis to meet the right-hand rule; finally, the assembly is appropriately simplified and saved as an X_T neutral file for use in the SpaceClaim software flow domain extraction.

[0009] On the basis of the above scheme and as a preferred scheme of the above scheme: the internal fluid domain of the double plunger pump in step 2 includes: the oil suction flow channel, the oil discharge flow channel, the distribution plate flow channel, the spherical annular oil film, the plunger flow channel and the cylinder plunger hole constitute the flow channel domain, and the flow domain extraction is mainly carried out through the SpaceClaim "volume extraction" function.

[0010] On the basis of the above scheme and as the preferred scheme of the above scheme: in the process of modeling the fluid domain in step 2, the modeling of the fluid part inside the sliding shoe is ignored, so the flow rate provided by the fluid volume is smaller than the actual flow rate; when using the PumpLinx software for simulation in step 2, it is necessary to calculate that the length of the plunger is 16mm when the swash plate is 0°, in preparation for the subsequent import of the PumpLinx software;

[0011] In step 2, in order to ensure the accuracy of subsequent simulation, it is necessary to cut the top of the cylinder and the plunger position in the SpaceClaim software;

[0012] In step 2, an oil film thickness of 0.02 mm needs to be retained between the plunger flow area and the distribution plate flow area. Use SOLIDWORKS software to establish a three-dimensional model of the annular spherical oil film, assemble and position it with the distribution plate flow area and the plunger flow area, and then only retain the annular spherical oil film model and physically suppress all other models. The spherical oil film is saved in STL format.

[0013] On the basis of the above scheme and as a preferred scheme of the above scheme: in step three, it is necessary to use ICEM software to divide the spherical annular oil film grid, and finally convert the generated grid into an unstructured grid and export the Nastran grid type.

[0014] On the basis of the above scheme and as the preferred scheme of the above scheme: in step three, the oil suction flow channel, oil discharge flow channel, and distribution plate flow channel flow area are divided using the general grid tool of the PumpLinx software, and the appropriate relative or absolute maximum grid size, minimum grid size, and surface grid size are set. The grids of the damping holes and damping grooves on the distribution plate need to be encrypted, and the flow area composed of the cylinder body and the plunger needs to be divided using the "Rotor TemplateMesher" grid template provided by the PumpLinx software, and the number of plungers, rotation vector, relative maximum grid size, relative minimum grid size, and relative surface grid size are set.

[0015] On the basis of the above scheme and as a preferred scheme of the above scheme: in step three, the spherical annular oil film Nastran Grid file saved by the ICEM software needs to be imported for grid assembly.

[0016] On the basis of the above scheme and as the preferred scheme of the above scheme: in step four, it is necessary to establish the oil suction flow channel, the oil discharge flow channel and the distribution plate flow area contact pair, the distribution plate flow area and the oil film contact pair, the oil film and the plunger flow area contact pair, the cylinder top and the cylinder body phase exchange area (Cylinder Cap Remain) and the cylinder top flow area (Cylinder Cap) contact pair, and the cylinder top and the cylinder body phase exchange area (Cylinder Cap Remain) and the cylinder surface (Cylinder Wall) contact pair.

[0017] On the basis of the above scheme and as the preferred scheme of the above scheme: in step five, a simulation model and corresponding parameter settings are selected, the simulation model includes a turbulence model and a cavitation model, and the parameter settings include residual convergence accuracy, discrete format and relaxation factor in the turbulence model; residual convergence accuracy, discrete format, relaxation factor and cavitation model type in the cavitation model; dynamic viscosity, density, temperature, elastic modulus and saturated vapor pressure in the oil parameters.

[0018] On the basis of the above scheme and as a preferred scheme of the above scheme: the fluid simulation parameters in step six include the inclination angle, rotation speed, and rotation direction of the swash plate in the operating parameters; the inlet pressure, outlet pressure, and oil film leakage pressure in the boundary conditions; and the solver type, number of iterations, solution time, and file automatic saving frequency in the solution parameters.

[0019] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0020] (1) Use SpaceClaim software to extract volume, and process the plunger pump flow basin model through operations such as stretching, splitting, and mirroring, which greatly improves the modeling speed.

[0021] (2) The Cylinder Cap area is segmented and contact pairs are established separately to improve the accuracy of the simulation model.

[0022] (3) Use ICEM software to perform high-quality meshing on the spherical annular oil film, save it as a Nastran mesh type and import it into PumpLinx software. This can improve the simulation accuracy of the duplex plunger pump and optimize the flow distribution structure through the characteristics of the spherical annular oil film.

[0023] (4) By setting the simulation parameters of the duplex piston pump, under the condition of the same speed, not only the same load and the same swash plate inclination angle of the dual pump outlets can be realized, but also different loads and different swash plate inclination angles of the dual pump outlets can be realized, which can meet the simulation requirements of the working characteristics of the duplex axial piston pump and can also meet the visualization of the internal flow of the piston pump, thereby improving the efficiency of structural optimization design, shortening the product development cycle, and saving R&D costs.

[0024] (5) This method can not only be used to study double-piston pumps, but can also be used for single spherical distribution piston pumps, which has a certain universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the flow chart of a double-piston pump flow field simulation method for a spherical oil film proposed by the present invention;

[0026] Figure 2 A schematic diagram of the flow region division of a double-type plunger pump cylinder body and plungers according to an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the overall flow area of ​​a double plunger pump according to an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of a meshing surface of a double plunger pump Pumplinx plunger of an embodiment of the present invention;

[0029] Figure 5 Schematic diagram of mesh division of a spherical annular oil film with a thickness of 0.02 mm for a double plunger pump according to an embodiment of the present invention;

[0030] in Figure 5 -a represents the establishment of a geometric topology interface. Figure 5 -b represents the block after the oil film geometry is divided into O-type blocks; Figure 5 -c represents the interface for line and surface association; Figure 5 -d represents the interface for node settings; Figure 5 -e stands for viewing the mesh quality interface;

[0031] Figure 6 It is a schematic diagram of the overall flow basin grid of a double plunger pump according to an embodiment of the present invention;

[0032] Figure 7 It is a schematic diagram of the watershed grid data interaction surface of a double plunger pump according to an embodiment of the present invention;

[0033] Figure 8 It is a schematic diagram of the outlet flow rate and plunger chamber pressure characteristic curve of the double plunger pump according to an embodiment of the present invention;

[0034] in Figure 8 -a, 8-b, 8-c are the characteristic curves of the instantaneous flow rate, average flow rate at the outlet of the front pump and the rear pump, and the pressure of the plunger cavity when the operating parameters are: inlet pressure 0.3Mpa, speed 1800rpm, load 30Mpa, and swash plate inclination angle 16.2°;

[0035] Figure 8 -d, 8-e, 8-f are characteristic curves of the instantaneous flow rate, average flow rate at the outlet of the front pump and the rear pump, and the pressure of the plunger cavity when the operating parameters are inlet pressure of 0.3Mpa, speed of 1800rpm, front pump load of 30Mpa, swash plate inclination of 16.2°, rear pump load of 20Mpa, and swash plate inclination of 12°;

[0036] Fig. 9 The characteristic curve diagram of the instantaneous flow rate, gas volume fraction and oil film pressure of the double plunger pump of the embodiment of the present invention;

[0037] Fig. 9 -a, 9-b, 9-c are characteristic curves of the instantaneous flow rate, gas volume fraction and oil film pressure of the single plunger of the front pump and the rear pump respectively when the double plunger pump of the embodiment of the present invention is under the working parameters of: inlet pressure 0.3Mpa, speed 2000rpm, load 35Mpa, swash plate inclination angle 16.2°;

[0038] Fig.10The cloud diagram of the volume percentage of gas cavitation occurring at the damping groove position when the double plunger pump according to the embodiment of the present invention is in the working condition parameters: inlet pressure 0.3Mpa, speed 2000rpm, load 35Mpa, swash plate inclination angle 16.2°; DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to specific embodiments in conjunction with the accompanying drawings;

[0040] like Figure 1 As shown, a double-piston pump flow field simulation method for a spherical oil film according to an embodiment of the present invention includes the following specific implementation steps.

[0041] (1) Step 1: Establish the geometric model of the double piston pump

[0042] The geometric model of the double-coupled plunger pump is mainly composed of a front pump, a rear pump and a shared intermediate body, in which a common oil suction port is shared on the intermediate body, and two oil discharge ports are used separately. The rotating shafts of the two pumps are connected by a coupling to meet the synchronous control of the speed of the two pumps. Each pump has a separate variable mechanism, which can realize the separate operation and combined operation of the two pumps. Figure 6 .

[0043] The main structure of the double pumps is the same. Each plunger pump is composed of a distribution plate, a cylinder body, a plunger, a sliding shoe, and a swash plate. Each plunger pump has nine plungers. When the parts are assembled, the inclination angle of the swash plate is set to 0°, and a plunger hole of the cylinder body is facing the inner dead center of the distribution plate. When establishing the geometric model, the origin position is at the intersection of the cross section in the intermediate body and the rotation axis, which is convenient for the subsequent extraction of the plunger flow field and the assembly of the spherical annular oil film. The rotation axis is located on the Z axis of the three-dimensional coordinate system, and rotates from the positive semi-axis of the X axis to the positive semi-axis of the Y axis, satisfying the right-hand rule;

[0044] Finally, the assembly is appropriately simplified and saved as an X_T neutral file for use in watershed extraction using the SpaceClaim software.

[0045] (2) Step 2: Establish a double plunger pump watershed

[0046] Usually, when fluid simulation analysis is performed, the flow domain is usually the external flow domain. It is necessary to establish an external flow field, and then the simulation flow domain can be obtained through Boolean operations. However, in the present invention, since the working flow domain of the double-coupled plunger pump is the internal flow domain, it is necessary to use SpaceClaim software to extract the flow domain of the internal flow channel according to the working principle of the double-coupled plunger pump. The main internal flow domains include: the oil suction flow channel, the oil discharge flow channel, the distribution plate flow channel, the flow channel between the cylinder body and the plunger, and the spherical annular oil film flow domain.

[0047] In particular, the spherical annular oil film flow area cannot be ignored. Considering the spherical annular oil film can not only improve the simulation accuracy, but also optimize the plunger pump structure according to the data on the oil film. Since the PumpLinx software cannot divide the spherical annular oil film grid, it is necessary to draw the spherical annular oil film model separately and perform grid division.

[0048] (2.1) Extraction of oil suction channel, oil discharge channel and distribution plate flow area

[0049] First, import the X_T neutral file of the duplex assembly into the watershed extraction of SpaceClaim software, and physically suppress the components that are not related to the watershed extraction. Since the front and rear pumps of the duplex plunger pump have the same structure, the corresponding watersheds are mirror-symmetric through the intermediate body. Only the watershed of the front pump can be extracted, and the watershed of the rear pump can be obtained through the "mirror" function. The symmetrical watersheds in the following operations are all obtained through the "mirror" function.

[0050] (2.1.1) Extraction of oil suction channel flow area

[0051] Click "Prepare" and "Volume Extraction" in the SpaceClaim software, select the oil inlet of the intermediate body of the plunger pump and the surface in contact with the distribution plate as the closed surface, then click any surface of the closed volume of the oil suction channel and click "Finish".

[0052] (2.1.2) Extraction of oil drainage channel basin

[0053] Click "Prepare" and "Volume Extraction" in the SpaceClaim software in sequence, select the oil discharge port of the piston pump intermediate body, the control valve contact surface, and the distribution plate contact surface as the closed surface, then click any surface of the closed volume of the oil discharge channel and click "Finish".

[0054] (2.1.3) Flow distribution plate flow area extraction

[0055] Click "Prepare" and "Volume Extraction" in the SpaceClaim software in sequence, select the two end faces of the distribution plate as the closed surfaces, click the waist groove of the distribution plate, the low-pressure waist groove, and the vibration reduction hole as the internal surfaces, and click "Finish".

[0056] (2.2) Plunger and cylinder flow area extraction

[0057] (2.2.1) Assembly

[0058] When using the PumpLinx software for simulation, the length of the top of the cylinder waist groove and the bottom of the plunger of the imported plunger pump flow model is required to be the length when the inclined plate inclination angle is 0°, that is, Figure 2The axial length of the middle piston pump is to ensure that the maximum displacement of the piston pump and the accuracy of the simulation can be met during simulation. The axial length of the piston pump used in this invention is calculated to be 16mm, and then a reference surface is established to assemble the cylinder body and one of the plungers.

[0059] (2.2.2) Watershed extraction

[0060] Click "Prepare" and "Volume Extraction" in the SpaceClaim software, select the bottom surface of the cylinder waist groove and the bottom surface of the plunger ball head as the closed surface, click one of the flow basin surfaces, and click "Finish".

[0061] (2.2.3) Watershed segmentation

[0062] Since the Pumpl inx software cannot identify the part of the cylinder cap that contacts the cylinder, in order to ensure the accuracy of the simulation, the cylinder cap remains need to be cut out, and the top of the cylinder and the plunger position need to be cut, such as Figure 2 shown.

[0063] (2.3) Establishment of spherical annular oil film flow domain

[0064] Use SOLIDWORKS software to build a three-dimensional model of the annular spherical oil film, and use the "component", "assembly" and "tangent" functions in SpaceClaim software to position it with the distribution plate flow area and the bottom of the cylinder. Only the annular spherical oil film model is retained, and all other models are physically suppressed. This step is to enable the subsequent mesh to be imported into the PumpLinx software to be directly and accurately positioned with other flow areas. Then the spherical annular oil film model is saved as STEP format to prepare for ICEM meshing.

[0065] (2.4) Assembly of the overall watershed model

[0066] like Figure 3 The final overall flow area of ​​the plunger pump is shown. Finally, the remaining parts of the spherical annular oil film model are physically suppressed and saved as an STL surface file format that can be recognized by the PumpLinx software.

[0067] (3) Step 3: Grid division of double plunger pump flow basin

[0068] (3.1) Importing the plunger pump watershed model and naming the surface

[0069] (3.1.1) Importing the plunger pump flow basin model

[0070] Open the PumpLinx software, create a new simulation example, click "Import / ExportGeometry or Grid" under the "Mesh" option and select "Import Surface", and finally click "Import Surface From STLTriangulation Files" to import the STL surface file saved in (2.4) into the PumpLinx software.

[0071] (3.1.2) Name of plunger pump flow basin model surface

[0072] Since the imported STL plunger pump watershed surface file is a whole, it is necessary to use the "Spl it / Combine Geometry or Grid" function under the "Mesh" option. Specifically, through the "Spl it by Angle", "Spl it Disconnected" and "Combine" functions, the plunger pump watershed is divided into the suction channel watershed Inlet, the discharge channel watershed Outlet_1, Outlet_2, the distribution plate watershed VP_1, VP_2 (including: L_VP1, H_VP1, Damping1, L_VP2, H_VP2, Damping2), the plunger watershed Piston-1, Piston-2, and the Cyl inder Cap Remain_1, Cyl inder CapRemain_2.

[0073] (3.2) Grid division of oil suction channel, oil discharge channel and distribution plate flow area

[0074] (3.2.1) Grid division of oil suction channel and oil discharge channel

[0075] Click "Mesh", "General Mesher", "Normal Mode", "Absolute" in sequence, select all surfaces of the oil suction and discharge channel, set the "Maxium Cel Size" to 2mm, the "Minium Cel Size" to 0.2mm, and the "Cel Size on Surfaces" to 1.5mm, and finally click "Create Mesh".

[0076] (3.2.2) Grid division of flow distribution plate basin

[0077] (3.2.2.1) Grid division of the flow area of ​​high pressure waist groove of the distribution plate

[0078] Click "Mesh", "General Mesher", "Normal Mode", "Absolute" in sequence, select all surfaces of the high-pressure waist-shaped trough basin, set "Maxium Cel Size" to 1.5mm, "Minium Cel Size" to 0.008mm, and "Cel Size on Surfaces" to 0.7mm. Due to the existence of triangular damping grooves, refinement and encryption are required. Click "Create a refinement zone", set the encrypted mesh size to 0.3mm, set the diagonal coordinates to (23,-27,67.5) and (8,-45,75.5), and finally click "Create Mesh".

[0079] (3.2.2.2) Grid division of low-pressure waist-shaped trough flow area of ​​distribution plate

[0080] Click "Mesh", "General Mesher", "Normal Mode" and "Absolute" in sequence, select all surfaces of the low-pressure waist-shaped trough basin, set "Maxium Cel Size" to 1.5mm, "Minium Cel Size" to 0.008mm, and "Cel Size on Surfaces" to 0.7mm. Due to the existence of vibration reduction holes, refinement and encryption are required. Click "Create arefinement zone" and set the encrypted mesh size to 0.3mm. Set the diagonal coordinates to (-10, 30, 58.5) and (-22.5, 37, 59.8) respectively, and finally click "Create Mesh".

[0081] (3.2.2.3) Grid division of vibration reduction hole flow area

[0082] Click "Mesh", "General Mesher", "Normal Mode", "Absolute" in sequence, select all the faces of the vibration damping hole, set the "Maxium Cel Size" to 0.5mm, the "Minium Cel Size" to 0.008mm, the "Cel Size on Surfaces" to 0.3mm, and finally click "Create Mesh".

[0083] (3.3) Grid division of plunger and cylinder flow area

[0084] (3.3.1) Plunger mesh division

[0085] The software's built-in inclined disk piston pump plunger meshing module can be used to quickly and accurately perform meshing. The specific operations are as follows: first, the plunger flow basin surface is segmented, such as Figure 4 As shown, click "Mesh", "Rotor TemplateMesher", "Rotor Type" in turn, select the "Swash Plate Piston" template, select "Piston Wall", "Cylinder Wall", "Cyl inder Cap", and "Cyl inder MGI" in turn, set the "Number of Pistons" to 9, "Rotat ional Axis Vector" to (0,0,1), and "Swash Plate Center" to (0,0,183.5). Since the piston mesh size is a relative value, set the "Maxium Cel Size" to 0.005, "Minium Cel Size" to 0.0001, and "Cel Size on Surfaces" to 0.002, and finally click "Create Swash Plate Piston Mesh".

[0086] Cylinder cap, piston surface, cylinder surface, oil film interaction surface (Cylinder MGI);

[0087] (3.3.2) Cylinder Cap Remain Meshing

[0088] Click "Mesh", "General Mesher", "Normal Mode", "Absolute" in turn, select all faces of Cyl inderCap Remain, set "Maxium Cel Size" to 1.5mm, "Minium Cel Size" to 0.025mm, "Cel Size on Surfaces" to 0.7mm, and finally click "Create Mesh".

[0089] (3.4) Spherical annular oil film mesh division

[0090] (3.4.1) Modify the work path

[0091] Open the ICEM software and click "Change Working Directory" under the "File" option.

[0092] (3.4.2) Pre-processing

[0093] First, set the unit. Click "Settings" under "Model / Units" and select "Millimeters". Then click "ImportModel" under the "File" option and select the saved oil film STEP file. Finally, you need to establish the geometric topology, such as Figure 5 -a, click "Repair Geometry" under the "Geometry" option, change the "Tolerence" under the "Build Topology" option to 0.002mm, and then "Apply".

[0094] (3.4.3) Create Part

[0095] The purpose of establishing Part is to facilitate the subsequent block association. Click "Parts" under the "Model" option, then right-click "Create Part" and name the four faces of the oil film "Gap_Piston_MGI", "Gap_VP_MGI", "Gap_NEI_Outlet" and "Gap_WAI_Outlet" respectively.

[0096] (3.4.4) Block creation and segmentation

[0097] Click "Blocking", then name the block, select "CreateBlock" to select the entire oil film model, and finally click "Apply" to generate the block; click "Spl it Block" under the "Blocking" option to select "O grid Block", then click "Seclect Block(s)" to select the Block generated in the previous step, click "Seclect Face(s)" to select the two surfaces in the oil film thickness direction, and finally click "Apply", click "Delete Block" to delete the redundant ones in the middle, and the final block is as follows Figure 5 -b.

[0098] (3.4.5) Association

[0099] Figure 5 -c stands for association interface. Click "Blocking", select "Associate", and then select "Associate Edge to Curve" under "Edit Associates" to associate the line on the block to the corresponding edge of the geometry; then select "Associate Face to Surface" to associate the face on the block to the Part established in (3.4.3) in sequence.

[0100] (3.4.6) Meshing and quality

[0101] Set the number of nodes, click "Blocking", select "Pre-Mesh Params", "MeshingParameters", "Edge Params" in turn, such as Figure 5 -d represents the node setting interface. Set the number of nodes in the oil film radius direction to 51, the number of nodes in the thickness direction to 5, and the number of nodes in the circumferential direction to 101. Finally, click "Apply", then click "Model", "Blocking", "Pre-Mesh" to generate the pre-mesh, then click "Pre-Mesh Quality Histograms" under the "Blocking" option, and select "Orthogonal Quality" as the mesh evaluation standard, such as Figure 5 -e is the final mesh quality.

[0102] (3.4.7) Oil film grid export

[0103] Right-click "Pre-Mesh", select "Convert to Unstruct Mesh", then click "FEASolve Opt ions" "Setup Analysis Type", select the analysis type as "NASTRAN", and finally click "Write / ViewInputFile".

[0104] (3.5) Grid assembly

[0105] Click "Mesh" "Import / Export Geometry or Grid" "Import Grid" "ImportGrid From Nastran Grid Files" to import the grid generated in (3.4.7). Finally, you will get the following: Figure 6 The overall flow basin grid of the piston pump.

[0106] (4) Step 4: Establishing contact pairs of watershed grids

[0107] Select the surfaces that touch different watersheds, click "Geometric Entities" and "Connect Selected Boundaries via MGI" in turn, and finally generate the following Figure 7 Grid data interaction surface.

[0108] (5) Step 5: Select simulation model and corresponding parameter settings

[0109] (5.1) Selection of simulation model

[0110] Click "Model" "Select Modules" in sequence to add the "Turbulence" model and the "Cavitation" model.

[0111] (5.2) Model simulation parameter setting

[0112] (5.2.1) Turbulence model parameter setting

[0113] Click "Model", "Flow", "Turbulence" in sequence to set the convergence residual to 0.1, the velocity and pressure relaxation factors to 0.2, and keep the rest as default.

[0114] (5.2.2) Cavitation model parameter setting

[0115] Click "Model", "Flow", "Cavitation" in sequence, set the convergence residual to 0.1, set the cavitation model to "Equilibrium Dissolve Gas Model", open the "Cavitation Damage Model" option, and keep the rest as default.

[0116] (5.2.3) Oil parameter setting

[0117] Select all "Volumes" in "Geometric Entities", click the "Model" option in "Properties", and then set the oil density "Density" under "Common" to 870kg / m 3 , the gas mass fraction is designed to be 9e-05, the elastic modulus "Liquid Bulk Modulus" is set to 1500Mpa, the reference pressure "Liquid Reference Pressure" is one atmosphere 0.101325Mpa, the saturated vapor pressure "Saturation Pressure" is set to 0.0035Mpa, the temperature "Temperature" is set to 50℃, and the gravity "Gravity Force" is set to 9800mm / s2 along the negative direction of the Y axis.

[0118] (6) Step 6: Set fluid simulation parameters

[0119] (6.1) Working condition parameter setting

[0120] Click "Model", "Common", "Swash Plate Piston", select "Extended Mode" and set it to "Reference Pump", select "Revolutions" type in "Time Definition", set "Number of Revolutions" to 3, and set "Time Steps Per Piston Rotation" to 40, which means that a plunger pump rotates 360° in one cycle, and each sub-step rotates 1°, for a total of 3 simulations; in "Pump Configuration", set "Swash Plate Normal" to (0, 0.212556, 1) to represent a swash plate inclination of 12°; in "Angular Velocity Definition", according to the right-hand rule, set "Rotational Direction" to "Counterclockwise" and the rotation speed "Rotational Speed" to 1500rpm, then set the Cyl inder Cap Remain motion parameters, click "Geometric Entities", select the "Cyl inder Cap Remain" volume model, and then click "Common" "Volume The speed and direction of "Remesh" and "Rotation" remain consistent with the overall.

[0121] (6.2) Boundary condition setting

[0122] Set the oil suction port to Inlet, with a size of 0.3Mpa, set the two oil discharge ports to Outlet, with a size of 30Mpa, and set the oil film outlet to Outlet, with a size of 0.3Mpa.

[0123] (7) Step 7: Simulation starts

[0124] Click "Simulation", select "Start From Initial Values", set "Result SavingFrequency" to 180 steps, and finally click "Start" to start the simulation.

[0125] (8) Step 8: Result Analysis

[0126] Click "AddXY-Plot" to add the data curve graphs you need to view, such as the instantaneous flow rate at the outlet, the average flow rate, and the curve graph of the plunger cavity pressure versus the plunger rotation angle. Figure 8 As shown in the figure, the plunger outlet flow rate, gas volume fraction, and oil film pressure are plotted against the plunger rotation angle. Fig. 9 As shown in the figure, the cavitation cloud diagram is as follows: Fig.10 As shown, if you need to simulate a spherical distribution piston pump with other structures, just follow the above steps. If you need to simulate different working conditions, just adjust the corresponding parameters.

[0127] The method of the present invention can realize the characteristic analysis of different working parameters of the double-type plunger pump, and can be used as a reference for design optimization. Compared with the traditional design and numerical simulation methods, the efficiency and accuracy of design and simulation can be improved. The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A double plunger pump flow field simulation method for a spherical annular oil film, characterized in that: The following steps are involved: Step 1: Establish the geometric model of the duplex plunger pump; Step 2: Establish a double plunger pump watershed; Step 3: Grid division of the double plunger pump watershed; Step 4: Establishment of watershed grid contact pairs; Step 5: Select the simulation model and corresponding parameter settings; Step 6: Set fluid simulation parameters; Step 7: Simulation starts; Step 8: Result analysis.

2. The double plunger pump flow field simulation method of spherical annular oil film according to claim 1 is characterized in that: The geometric model of the double-connected plunger pump in step 1 is composed of a front pump, a rear pump and a shared intermediate body, wherein the intermediate body shares an oil suction port, and the two oil discharge ports are used separately. The rotating shafts of the front pump and the rear pump are connected by a coupling to meet the synchronous control of the speed of the two pumps. The front pump and the rear pump have separate variable mechanisms, which can realize the separate operation and confluence operation of the two pumps; The structures of the two pumps are identical and mirror-symmetrical. Each pump consists of a distribution plate, a cylinder body, a plunger, a sliding shoe and a swash plate. Each pump has nine plungers. When the parts are assembled, the inclination angle of the swash plate is set to 0°, and a plunger hole of the cylinder body is facing the inner dead center of the distribution plate. When the geometric model is established, the origin is located at the intersection of the cross section in the intermediate body and the rotation axis, which is convenient for the subsequent extraction of the plunger flow domain and the assembly of the spherical annular oil film. The rotation axis is located on the Z axis of the three-dimensional coordinate system, and it rotates from the positive semi-axis of the X axis to the positive semi-axis of the Y axis to meet the right-hand rule; finally, the assembly is appropriately simplified and saved as an X_T neutral file for use in the SpaceClaim software flow domain extraction.

3. The double plunger pump flow field simulation method of spherical annular oil film according to claim 1 is characterized in that: The internal fluid domain of the duplex plunger pump in step 2 includes: the oil suction flow channel, the oil discharge flow channel, the distribution plate flow channel, the spherical annular oil film, the plunger flow channel and the flow domain composed of the cylinder plunger hole, and the flow domain extraction is mainly carried out through the SpaceClaim "volume extraction" function.

4. The method for simulating the flow field of a double-type plunger pump of a spherical annular oil film according to claim 3 is characterized in that: In step 2, the modeling of the fluid domain inside the sliding shoe is ignored, so the flow rate provided by the fluid volume is smaller than the actual flow rate; When using the PumpLinx software for simulation in step 2, it is necessary to calculate the length of the plunger to be 16 mm when the swash plate is 0°, in preparation for the subsequent import of the PumpLinx software; In step 2, in order to ensure the accuracy of subsequent simulation, it is necessary to cut the top of the cylinder and the plunger position in the SpaceClaim software; In step 2, an oil film thickness of 0.02 mm needs to be retained between the plunger flow area and the distribution plate flow area. Use SOLIDWORKS software to establish a three-dimensional model of the annular spherical oil film, assemble and position it with the distribution plate flow area and the plunger flow area, and then only retain the annular spherical oil film model and physically suppress all other models. The spherical oil film is saved in STL format.

5. The flow field simulation method of a double-type plunger pump of a spherical annular oil film according to claim 1 is characterized in that: In step three, ICEM software needs to be used to divide the spherical annular oil film mesh, and finally the generated mesh is converted into an unstructured mesh and exported to the Nastran mesh type.

6. The method for simulating the flow field of a double-type plunger pump of a spherical annular oil film according to claim 1, characterized in that: In step 3, the suction channel, discharge channel, and distribution plate channel flow areas are divided using the general grid tool of the PumpLinx software. The appropriate relative or absolute maximum grid size, minimum grid size, and surface grid size can be set. The meshes of the damping holes and damping grooves on the distribution plate need to be encrypted. The flow area composed of the cylinder body and the plunger needs to be divided using the "Rotor Template Mesher" grid template provided by the PumpLinx software. The number of plungers, rotation vector, relative maximum grid size, relative minimum grid size, and relative surface grid size must be set.

7. The method for simulating the flow field of a double-piston pump of a spherical annular oil film according to claim 1, characterized in that: Finally in step three, you need to import the spherical annular oil film Nastran Grid file saved by the ICEM software for grid assembly.

8. The method for simulating the flow field of a double-piston pump of a spherical annular oil film according to claim 1, characterized in that: In step four, it is necessary to establish the contact pairs between the oil suction flow channel, the oil discharge flow channel and the distribution plate flow area, the distribution plate flow area and the oil film, the oil film and the plunger flow area, the cylinder top and the cylinder body mutual exchange area (Cylinder Cap Remain) and the cylinder top flow area (Cylinder Cap), and the cylinder top and the cylinder body mutual exchange area (Cylinder Cap Remain) and the cylinder surface (Cylinder Wall).

9. The method for simulating the flow field of a double-piston pump of a spherical annular oil film according to claim 1, characterized in that: In step five, select the simulation model and corresponding parameter settings. The simulation model includes turbulence model and cavitation model. The parameter settings include residual convergence accuracy, discrete format and relaxation factor in turbulence model; residual convergence accuracy, discrete format, relaxation factor and cavitation model type in cavitation model; dynamic viscosity, density, temperature, elastic modulus and saturated vapor pressure in oil parameters.

10. The flow field simulation method of a double-piston pump of a spherical annular oil film according to claim 1, characterized in that: The fluid simulation parameters in step six include the swash plate inclination angle, rotation speed, and rotation direction in the operating parameters; the inlet pressure, outlet pressure, and oil film leakage pressure in the boundary conditions; and the solver type, number of iterations, solution time, and file automatic saving frequency in the solution parameters.

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