Creating the Spray Zone

Figure 23-6 Events parameters and Cylinder parameters panels

Creating the Spray Zone

In this section you will create a dummy sector mesh from which you can extract a spray zone mesh suitable for the ELSA model. This spray zone will be used at a later stage in this tutorial. You will also use the Sector panel to define cell counts and distributions within the template mesh. For definitions and illustrations of these parameters, see Chapter 6, “Axisymmetric Sector Meshing” in the User Guide.

To create the spray zone mesh:

•In the Create Template panel, click Make Sector

•In the Sector panel (see Figure 23-7), select Trimmed, spray from the drop-down menu at the top-left of the panel

•Set Azimuthal cone angle to 22.5

•Set Number of holes to 8

•Set Azimuthal cells to 9 and 18

•Select the Modify prisms toggle button and make sure that its value is set to 2

•Deselect the Include injector cells toggle button

•Select the Edit toggle button

•Set Source R, Z, diameter to 1.5, -1.2 and 1

•Set Spray extent to 15

•Set Axis angle to 13

•Set Planar cone angle to 26

•Set Radial cells to 6, 36 and 10

•Set Axial cells to 180, 30 and 4

•Click Create 2D

Figure 23-7 Sector panel for spray zone mesh

At this stage, you can create an edge that defines the top of the cylinder without the spray zone mesh. This edge is converted to a spline which will be used at a later stage in the tutorial. To create this spline:

•Zoom into the top of the cylinder mesh

•Enter the following command to create an edge that defines the bottom of the injector, the edges of the spray zone and the cylinder head, as shown in Figure 23-8

Edge, 1, Cursor

Figure 23-8 Spray zone edge

•Enter the following command to create Spline 3 from Edge 1

Spline, 3, Edge, 1

•In the Plot Tool, activate the Geometry window from the drop-down menu

•Click CPlot and zoom into Spline 3 near the spray zone

•Enter the following command to create spline break points in places where there should be sharp corners, as shown in Figure 23-9

SBreak

3

4

1

2

Figure 23-9 Spline break points

Next, create the dummy sector mesh and isolate the spray zone:

•In the Sector panel, click Trim

•When the corresponding child process is complete, click Get sector

•In the Plot Tool, set the Views option to View 0, -1, 0

•Enter the following command to isolate the spray zone cells by drawing a polygonal zone around them, as shown in Figure 23-10

CSet, Newset, Zone

Figure 23-10 Polygonal zone around spray zone cell

Figure 23-11 shows the spray zone cells.

Figure 23-11 Spray zone cells

Finally, modify some cells so that they match the nozzle shape and export the spray zone so that it can be used later on in the tutorial:

•Enter the following command to import a spline that represents the nozzle. This spline will be used as a guide for modifying cells in the spray zone.

Spline, Read, injector_hole.spl

•In the Plot Tool, deselect the Fill toggle button and click DPlot to display the spray zone and nozzle together

•Zoom into the area close to the nozzle, as shown in Figure 23-12

Figure 23-12 Nozzle spline and mesh

•Enter the following command to create diagonal mesh lines that approximate the nozzle, as shown in Figure 23-13.

CutHex, Cursor

Figure 23-13 Nozzle with modified cells

This operation creates a mesh line across a quad face between two picked vertices. Therefore, you can only use the CutHex command to cut one cell face at a time.

•Enter the following command to select vertices that are closest to the nozzle, as shown in Figure 23-14

VSet, Newset, Cursor

Figure 23-14 Nozzle vertices