Figure 19-12 Two-stroke trimmed cylinder template

At this stage, you can also merge the vertices on small-scale edges to improve the cell connectivity:

•Ensure the VMerge drop-down menu is set to

Edges

•In the Trim panel, enter 0.05 in the box next to

the VMerge button and click VMerge

• Click Put to put the updated template back into the trim database

Assembling the trimmed template

The final stage in generating a trimmed template is to add an extrusion layer and then assemble the full model:

•In the Trim panel, set Extrusion to 0.3

•Click Assemble

•When the child process is complete, the trimmed template is loaded into the Template panel, as shown in Figure 19-13

Figure 19-13 Two-stroke trimmed and assembled template

To display the extrusion layer, create a section plot through the centre of the cylinder, as shown in Figure 19-14:

•Enter the following commands to define the section, by specifying a point on the section plane and the direction of the normal to that plane:

SPoint, 0, 0, 0 SNormal, 0, 1, 0

• In the Plot Tool, change the display mode from Hidden to Section

•Set the Views option to View 0, 1, 0

Figure 19-14 Cross-section showing the extrusion layer

Running Star Setup

Run Star Setup to store the geometry data obtained so far and generate the files used in pro-STAR and STAR:

•In the Select panel, click Star Setup to open the Star setup panel

•Deselect the Use unwarper toggle button

•Select the Reset smoothers toggle button

•Select pro-STAR 4.20 from the pro-STAR drop-down menu

•Click Star setup

Checking the mesh

The Create Result panel generates the computational meshes used in STAR at specified crank angles. You can then check the mesh quality and validity before starting the analysis. The following description shows how to check the computational mesh at BDC and TDC.

To create a mesh at BDC:

•In the Select panel, click Create Result

•In the Create Result panel, set Angle (deg) to 540

•Select the Interpolate toggle button

•Click Create Result to create the mesh

at 540 degrees crank angle. Note that a result.d540.0.dbs file is created in the working directory. This is a database-format file containing the mesh at the specified crank angle

•When the child process is complete, click Read Result to read the mesh into the General Workspace window, as shown in Figure 19-15

•Enter command, Check, NegVolume to check that there are no cells with negative volumes

Figure 19-15 Two-stroke engine at 540 degrees crank angle

•Repeat the above process with Angle (deg) set to 720 to check the computational mesh at TDC, as shown in Figure 19-16

Figure 19-16 Two-stroke engine at 720 degrees crank angle