You are here: Fluid Machinery Templates and Tutorials > Scroll Compressor > Mesher

6.14.2 Scroll Compressor Mesher

This section explains the settings available in the Scroll template, to generate the dynamic mesh for the rotor. The template enables the creation of mesh with appropriate quality and minimal user effort. The leakages in the crescent pump can also be defined and controlled while meshing. The mesh related settings are accessed as follows:

Mesh Panel > Rotor Template Mesher

The following mesh related settings are available in the Geometry Tab of Properties Panel as shown in Figure 6.785 and Figure 6.786

Create/Replace Mesh: Allows the user to select one of the following:

• New Mesh: To create a new mesh.

• Store Build Mesh: To store the mesh settings without generating any mesh.

• Replace: scroll: To replace the existing mesh with new mesh settings.

 

Mesh Name: Allows the user to name the mesh prior to mesh creation. This option is available when New Mesh or Store Build Mesh is selected under Create/Replace Mesh.

 

Setup Options: Allows the user to create the mesh using one of the following modes:

• Normal Mode: This mode provides standard access to the basic parameters to create the mesh.
• Advanced Mode: This mode provides full access to all the meshing parameters to create the mesh.

Rotor Type: Select Scroll from the drop-down list.

Figure 6.785 - Rotor type-Scroll

Figure 6.786 - Build scroll mesh

The available parameters related to this template can be accessed by setting the Setup Options as Advanced Mode, as shown in Figure 6.786.

Rotor

This is used to assign the rotor of the scroll as follows:

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

Stator

This is used to assign the stator of the scroll as follows:

• Select the stator surface under CAD Surfaces in Geometric Entities Panel.
• Click Add Surfaces icon to the right of Stator or click Select Stator in the Properties Panel.

Stator End

This parameter is used to identify the stator end surfaces of the scroll compressor as follows (surface for selection is shown in Figure 6.787):

• Select stator end surface under CAD Surfaces in Geometric Entities Panel.
• Click Add Surfaces icon to the right of Stator End or click Select Stator End in the Properties Panel.

 

 

 

 

Figure 6.787 - Stator end surface

Note: 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 scroll rotor as: Coarse Normal Fine User Input

Figure 6.788 - Rotor mesh size - Scroll

 

 

 

 

Figure 6.789 - Rotor mesh size-Scroll: Coarse, Fine and Normal

User Input

The control parameters associated with User Input (see Figure 6.788) are:

• Points in Rotational Direction: Corresponds to the number of cell nodes in the rotational direction along one single 360 degree revolution of the rotor (orbiting scroll). The total number of control cells for the whole rotor is dependent on the design of the rotor.
• Points in Radial Direction: Corresponds to the number of cell nodes in the radial direction from the center to the edge of the compression 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 compression chamber. The number of control cells in this direction is (Points in Axial Direction – 1).

Rotational Axis Vector

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

Rotation Radius Shrinkage (%)

This enables to shrink or enlarge the radius of the rotor relative to the rotor center in terms of percentage. This is used primarily to avoid volume boundary intersections between the stator and rotor surfaces during rotation or to provide the correct known clearances between the two. This parameter is necessary to provide very accurate coordinates for good rotational performance.

 

 

 

 

Figure 6.792 - Scroll shrinkage (%)

Rotor Center: This specifies the center of the rotor in coordinates.

Stator Center: This specifies the center of the stator in coordinates.

Tip Seal Mesh This provides extra leakage path which affects the performance of scroll compressors. It is added as a Volume based on the parameters defined for Tip Seal Mesh. The seal is assumed to always stay on the outer side. The associated parameters to define tip seal mesh and its position are: Tip Seal Mesh Groove Width Groove Depth Tip Seal Width Tip Seal Depth Axial Gap Tip Seal Start Angle

Figure 6.793 - Tip Seal Mesh

 

 

 

 

Figure 6.794 - Model with tip seal

 

Smooth Rotor Mesh  

This allows to improve the scroll compressor mesh using a mesh smoothing algorithm, which maximizes cell face orthogonality and optimizes the cell density distribution.

• Max Iterations: Specifies the number of iterations, the smoothing algorithm has to run for. The default value is 25, usually optimal for most cases. However, the user can adjust this to capture any desirable mesh characteristics.

• Relaxation (0 < r < 2): Specifies the percentage (i.e. 70% = 0.7 for relaxation value) of the calculated node (cell volume corner point) position displacement increment calculated during the smoothing process. The default value is 1.0.

Figure 6.796 - Relaxation

Figure 6.797 - Visual representation of relaxation

Once, the parameters of meshing are defined, click Build Scroll Mesh in the Geometry Tab of the Properties Panel. The Scroll mesh is created and added under the Built Meshes and corresponding Volumes in the Geometric Entities Panel. Also, Scroll module is added to the Model Panel.