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Building the Mesh

This section describes the step-by-step procedure for preparing the mesh for the swash plate piston pump. The Rotor Template Mesher is used to create the piston-cylinder assembly mesh and the General Mesher is used to create the mesh for the inlet, outlet and the valve plate.

Inlet and Outlet Meshes Select General Mesher in the Mesh Panel. Select CAD Surfaces inlet_inlet, inlet_mgi, inlet_walls, outlet_mgi, outlet_outlet, outlet_walls in the Geometric Entities Panel and click Add Surfaces icon for CAD Surfaces in the Properties Panel. Enter the Maximum Cell Size as 0.01, Minimum Cell Size as 0.001 and Cell Size on Surfaces as 0.005 in the Properties Panel. Click Create Mesh. A new mesh mesh is created under Built Meshes in the Geometric Entities Panel. The meshed volumes inlet and outlet are generated under Volumes.

Figure 6.427 - Inlet and Outlet mesh settings

Valve plate Mesh Select General Mesher in the Mesh Panel. Select Advanced Mode for Setup Options drop-down list. Select CAD Surfaces vp_mgi_pistons, vp_mgi_ports, vp_walls in the Geometric Entities Panel and click Add Surfaces icon for CAD Surfaces in the Properties Panel. Enter Maximum Cell Size as 0.005, Minimum Cell Size as 0.001 and Cell Size on Surfaces as 0.0025 in the Properties Panel. Select Combined with Patches for Sub-feature Options drop-down list. Select No for Volume Order by Size drop-down list. Click Create Mesh. A new mesh vp is created under Built Meshes and vp_1, vp_2, vp_3, vp_4 and vp_5 are generated under Volumes in the Geometric Entities Panel. Select Split/Combine Geometry or Grid in the Mesh Panel. Select vp_1, vp_2, vp_3, vp_4 and vp_5 under Volumes. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as valve_plate. Select the Boundaries as shown in Table 6.19. Select Combine from the Operation drop-down list in the Properties Panel. Click Combine and rename with corresponding names as in Table 6.19.

Figure 6.428 - Valve plate mesh settings

Boundaries	Rename as
vp_walls_1, vp_walls_2, vp_walls_3, vp_walls_4 and vp_walls_5	vp_walls
vp_mgi_pistons_1, vp_mgi_pistons_2, vp_mgi_pistons_3, vp_mgi_pistons_4, vp_mgi_pistons_5	vp_mgi_pistons
vp_mgi_ ports_1, vp_mgi_ ports_2, vp_mgi_ ports_3, vp_mgi_ ports_4, vp_mgi_ ports_5	vp_mgi_ ports

Table 6.19 - Combine and rename Boundaries

 

´	Note: Two connected Volumes, such as the inlet and valve plate, or valve plate and outlet cannot be meshed together using the General Mesher.

 

Piston - cylinder assembly Mesh Select Rotor Template Mesher in the Mesh Panel. Select Swash Plate Piston from the Rotor Type drop-down list in the Properties Panel Select CAD Surfaces piston_end and piston_wall in the Geometric Entities Panel, click Add Surfaces icon for Piston Wall in the Properties Panel. Similarly select CAD Surfacepiston_cylinder for Cylinder Wall, piston_cap for Cylinder Cap, and piston_mgi for Cylinder MGI. Enter the parameters as follows. Number of Pistons: 9 Rotational Axis Vector: 0,0,1 Swash Plate Center: 0,0,-0.2 Maximum Cell Size: 0.01 Minimum Cell Size: 0.001 Cell Size on Surfaces: 0.005 Click Build Swash Plate Piston Mesh. The new mesh piston is created under Built Meshes in the Geometric Entities Panel. The meshed volume piston is generated under Volumes.

Figure 6.429 - Piston - cylinder mesh settings

Note: The geometry contains only one piston. The mesh for all the pistons specified under Number of Pistons is automatically generated by the Rotor Template Mesher. The imported geometry does not include any leakage gap by default. The parameters for the gaps can be adjusted by selecting Advanced Mode under Setup Options in the Properties Panel.

 

Figure 6.430 - Inlet and Outlet mesh

Figure 6.431 - Valve plate mesh

Figure 6.432 - Piston-cylinder assembly mesh

Create interfaces

In this section, the Mismatched Grid Interfaces (MGIs) are generated between Boundaries.

The steps to create the MGIs are shown below :

1. Geometric Entities Panel > Volumes > Boundaries, elect Boundaries as shown in Table 6.20.

2. Click Connect Selected Boundaries via MGI icon to create the MGI entities (see, Figure 6.433).

A group display of entities can be viewed using the Group Entities by Volumes/Types icon at Geometric Entities Panel toolbar.

Connecting interfaces	Boundaries	Entity
Ports and valve plate	inlet_mgi, outlet_mgi and vp_mgi_ports	MGI01
Pistons and valve plate	piston_mgi and vp_mgi_pistons	MGI02

Table 6.20 - Creating interfaces

 

The new entities are created under MGI in Volumes (see, Figure 6.434).

Figure 6.433 - Connecting interfaces

Figure 6.434 - Created interfaces

 

Note: If MGIs are created by connecting the wrong boundaries, delete the created MGIs by clicking on Delete Selected Geometric Entity icon and recreate the MGIs.