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Computational domain

This section explains the preparation of surfaces to create the domain. This is done with the operations splitting, combining and renaming of the surfaces.

Pump Surfaces

1. Select CAD Surfaces pump in the Geometric Entities Panel.
2. Select Split/Combine Geometry or Grid in the Mesh Panel.
3. Select Split Disconnected from the Operation drop-down list in the Properties Panel, click Split Disconnected. Ten new CAD Surfaces are created in the Geometric Entities Panel.
4. Rename the CAD Surfaces pump_01, pump_02, pump_03 and pump_04 as rotor_chamber, slider1, rotor and slider2 respectively.
5. Select CAD Surfaces pump_05 and pump_06. Select Combine from the Operation drop-down list in the Properties Panel.
6. Click Combine and rename as port. Similarly select CAD Surfaces pump_08, and pump_09, click Combine and rename as groove.
7. Rename the CAD Surfaces pump_07 and pump_10 as control and release respectively.

Port Surfaces Select CAD Surfaces port in the Geometric Entities Panel. Select Split by Angle from the Operation drop-down list in the Properties Panel. Enter 75 deg for Angle, click Split by Angle. Eight new CAD Surfaces are created in the Geometric Entities Panel. Select CAD Surfaces port_01, port_02, port_07, and port_08. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as port_walls. Similarly select CAD Surfaces pump_04 and pump_06, click Combine and rename as port_mgi_rotor. Rename CAD Surfaces port_03 and port_05 as port_inlet and port_outlet respectively.

Figure 6.254 - Port surfaces

Rotor Surfaces Select CAD Surfaces rotor in the Geometric Entities Panel. Select Split by Angle from the Operation drop-down list in the Properties Panel. Enter 75 deg for Angle and 20 for Maximum No. of Splits. Click Split by Angle. Twenty one new CAD Surfaces are created in the Geometric Entities Panel. Select CAD Surfaces rotor_03, rotor_04, rotor_05, rotor_06, rotor_07, rotor_08 and rotor_09. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as rotor_rotor. Select the remaining rotor CAD Surfaces, click Delete Selected Geometric Entity icon to delete the entities. Select CAD Surfaces rotor_chamber in the Geometric Entities Panel. Select Split by Angle from the Operation drop-down list in the Properties Panel. Enter 75 deg for Angle and 20 for Maximum No. of Splits. Click Split by Angle. Three new CAD Surfaces are created in the Geometric Entities Panel. Rename CAD Surfaces rotor_chamber_1 as rotor_chamber_wall Select CAD Surfaces rotor_chamber02 and rotor_chamber03. Click on Delete Selected Geometric Entity icon to delete the entities.

Figure 6.255 - Rotor surfaces

´	Note:  The surfaces are deleted as they are not needed to create the mesh.

 

Release Surfaces Select CAD Surfaces release in the Geometric Entities Panel. Select Split by Angle from the Operation drop-down list in the Properties Panel. Enter 75 deg for Angle, click Split by Angle. Three new CAD Surfaces are created in the Geometric Entities Panel. Rename CAD Surfaces release_01, release_02 and release_03 as release_wall, release_open and release_mgi_rotor respectively.

Figure 6.256 - Release surfaces

Control surfaces Select CAD Surfaces control in the Geometric Entities Panel. Select Split by Angle from the Operation drop-down list in the Properties Panel. Enter 75 deg for Angle, click Split by Angle. Three new CAD Surfaces are created in the Geometric Entities Panel. Rename the CAD Surfaces control_01, control_02 and control_03 as control_wall, control_inlet and control_mgi_slider respectively.		Figure 6.257 - Control surfaces
Groove surfaces Select CAD Surfaces groove in the Geometric Entities Panel. Select Split by Angle from the Operation drop-down list in the Properties Panel. Enter 75 deg for Angle, click Split by Angle. Six new CAD Surfaces groove_01 to groove_06 are created in the Geometric Entities Panel. Select CAD Surfaces groove_01 and groove_02. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as groove_wall. Similarly select CAD Surfaces groove_03 and groove_04. Click Combine and rename as groove_mgi_chamber. Select CAD Surfaces groove_05 and groove_06. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as groove_mgi_port.		Figure 6.258 - Groove surfaces

Note: In addition to the usual surface preparation for vane pump modelling, one needs to prepare the Surfaces/Boundaries for the slide bars. Since the mesh movement of the sliders is modelled using Rotation (1 DOF) module in conjunction with the Circumferential Valve module, the slider Boundaries is divided into the surfaces: Valve, Valve End, and Cylinders

 

Slider1 surfaces

1. Select CAD Surfacesslider1 in the Geometric Entities Panel.
2. Select Split by Angle from the Operation drop-down list in the Properties Panel.
3. Enter 75 deg for Angle, click Split by Angle. Six new CAD Surfaces slider1_01 to slider1_06 are created in the Geometric Entities Panel.
4. Rename slider1_01, slider1_02, slider1_03, slider1_04 and slider1_05 as slider1_ends, slider1_valve, slider1_top, slider1_bot and slider1_cylinder_in respectively.
5. Select CAD Surfaces slider1_valve and slider1_06.
6. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as slider1_valve.

Note: The Outer Cylinder needs to be split away from the slider1_ends, but this will require small splitting angles. The curved edges make it more difficult to separate surfaces, thus creating the necessity of using a small splitting angle. It is also recommended to limit the Maximum No. of Splits.

7. Split the CAD Surfaces of the Table 6.6 as follows.

• Geometric Entities Panel > Select the CAD Surfaces > Properties Panel > Select Split by Angle from the Operation drop-down list.
• Enter Angle > Enter Maximum No. of Splits > Click Split by Angle.

CAD Surfaces	Angle (deg)	Maximum No of Splits
slider1_ends	1	5
slider1_ends_02	0.1	2

Table 6.6 - Split/Rename Slider1 CAD surfaces

Select CAD Surfaces slider1_ends_02 and slider1_ends_02_02.

Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as slider1_cylinder_out. Similarly select remaining slider1_ends CAD Surfaces, click Combine and rename as slider1_endsrefer, Figure 6.259.

Slider2 surfaces

1. Select the CAD Surfaces slider2 in the Geometric Entities Panel.
2. Select Split by Angle from the Operation drop-down list in the Properties Panel.
3. Enter 75 deg for Angle, click Split by Angle. Six new CAD Surfaces are created in the Geometric Entities Panel.
4. Rename slider2_01, slider2_02, slider2_03, slider2_04 and slider2_05 as slider2_ends, slider2_valve, slider2_bot, slider2_top and slider2_cylinder_in respectively.
5. Select CAD Surfacesslider2_valve and slider2_06. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as slider2_valve.

Note: The Outer Cylinder needs to be split away from the slider2_ends, but this will require small splitting angles. The curved edges make it more difficult to separate surfaces, thus creating the necessity of using a small splitting angle. It is also recommended to limit the Maximum No. of Splits.

6. Select the CAD Surfaces slider2_ends in the Geometric Entities Panel.

7. Select Split by Angle from the Operation drop-down list in the Properties Panel.
8. Enter 1 deg for Angle and 5 for Maximum No. of Splits, click Split by Angle. Five new CAD Surfaces are created in the Geometric Entities Panel.
9. Select CAD Surfaces slider2_ends_03 and rename as slider2_cylinder_out.
10. Select the remaining slider2_ends CAD Surfaces. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as slider2_ends refer, Figure 6.260.

Figure 6.259 - Slider1 surfaces

Figure 6.260 - Slider2 surfaces