You are here: Fluid Machinery Templates and Tutorials > Crescent Pump > Mesher > Crescent Chamber Meshing

Crescent Chamber Meshing

This section explains the settings for the crescent chamber mesh generated using the Rotor Template Mesher. This involves selection of the surfaces, directional characteristics of the mesh and other advanced mesh settings.

The parameters related to Crescent meshing can be accessed by setting the Setup Options to Advanced Mode, as shown in Figure 6.295.

Inner Rotor

This is used to assign the inner rotor of the crescent pump as follows:

• Select the inner rotor surface under CAD Surfaces in the Geometric Entities Panel.
• Click Add Surfaces icon to the right of Inner Rotor, or click Select Inner Rotor in the Properties Panel.

Outer Rotor

This is used to assign the outer rotor of the crescent pump as follows:

• Select the outer rotor surface under CAD Surfaces in Geometric Entities Panel.
• Click Add Surfaces  icon to the right of Outer Rotor, or click Select Outer Rotor in the Properties Panel.

Crescent Inside Wall

This is used to assign the crescent inside wall as follows:

• Select the crescent inside wall surface under CAD Surfaces in Geometric Entities Panel.
• Click Add Surfaces icon to the right of Crescent Inside Wall, or click Select Crescent Inside Wall in the Properties Panel.

Crescent Outside Wall

This is used to assign the crescent outside wall as follows:

• Select the crescent outside wall surface under CAD Surfaces in Geometric Entities Panel.
• Click Add Surfaces icon to the right of Crescent Outside Wall, or click Select Crescent Outside Wall in the Properties Panel.

Note:  Simerics-MP+ automatically cycles from one operation to the next in the sequence: Select Inner Rotor, Select Outer Rotor, Select Crescent Inside Wall, Select Crescent Inside Wall to Build Crescent Mesh. For the Build Crescent Mesh option to be available, the rotor and crescent inside and outside wall surfaces must first be assigned. The picking sequence can be repeated/reset in the event that a boundary is incorrectly identified or a new mesh is desired. The boundary conditions are automatically set by the template for the assigned surfaces.

Rotor Mesh Size

This allows to control the resolution of the mesh created in the crescent pumping chamber as: Coarse Normal Fine User Input

Figure 6.296 - Rotor mesh size-Crescent

The control parameters associated with User Input (see, Figure 6.296) are: Points in Rotational Direction: Corresponds to the number of cell nodes in the rotational direction along the circumference of the pumping chamber. The number of control cells in this direction is (Points in Rotational Direction – 1). Points in Radial Direction: Corresponds to the number of cell nodes in the radial direction from the center to the edge of the pumping chamber. The number of control cells in this direction is (Points in Radial Direction – 1). Points in Axial Direction: Corresponds to the number of cell nodes in the axial direction from the bottom to the top of the pumping chamber. The number of control cells in this direction is (Points in Axial Direction – 1).

Figure 6.298 - User input mesh size-Crescent

 

Number of Inner Teeth: Specify the number of teeth in the inner rotor. Number of Outer Teeth: Specify the number of teeth in the outer rotor.

Figure 6.299 - Inner and Outer teeth-Crescent

Note:Although the Number of Inner Teeth or Number of Outer Teeth do not affect the mesh generation, they are typically specified during the meshing operation and then automatically copied over to the Pump Configuration menu.

Rotational Axis Vector

The direction of the axis of rotation of the inner rotor in the laboratory reference frame, specified in coordinates.

Inner Rotor Center The center point of the inner rotor in the pump. In practice, it can be specified anywhere along the axis of symmetry in coordinates. Outer Rotor Center The center point of the outer rotor in the pump. In practice, it can be specified anywhere along the axis of symmetry in coordinates.

Figure 6.301 - Inner and Outer rotor centers-Crescent

 

Mesh Center (0 Inner, 1 Outer)

The mesh center is a reference point used in the mesh generation process. It is the origin of the mesh coordinate system. It lies along a line connecting the inner and outer rotor centers and ranges between 0 and 1; 0 being the inner rotor center and 1 being the outer rotor center. This parameter can be used to adjust the mesh, when meshing difficulties arise. The default value of 0.5 (the average of the inner and outer rotor center coordinates) should be used for most cases (see Figure 6.295).

Gear Deformation This deforms one of the rotors when two rotors get close to each another, to avoid collision. The Outer Gear (corresponds to outer rotor) or the Inner Gear (corresponds to inner rotor) can be deformed by specifying a Minimum Gap Size.

Figure 6.302 - Gear deformation- Crescent