Chapter 10 USING THE AUTOMATIC 2D TEMPLATE

The following tutorial data files are used in this chapter:

AUTO_2D/geometry.dbs

AUTO_2D/vlift01.dat (Valve 1 lift profile)

AUTO_2D/vlift02.dat (Valve 2 lift profile)

AUTO_2D/vlift03.dat (Valve 3 lift profile)

AUTO_2D/vlift04.dat (Valve 4 lift profile)

PANELS/training.pnl

The model created at the end of this tutorial is saved to file: save_es-ice.auto2d

This tutorial demonstrates the process of generating a 2D base mesh using the automatic 2D template feature. This generates an unstructured uniform mesh for each valve section that is much quicker to produce compared to the manual method of creating structured meshes. The automatic method is also better suited to complex cylinder geometries, as you are not constrained by the requirements of structured meshes.

The problem in this case is a diesel engine with a flat cylinder head and one injector in the centre of the cylinder. These characteristics make the geometry ideal for automatic 2D template meshing.

The tutorial highlights several capabilities of automatic 2D template meshing, giving you the ability to rapidly produce high-quality, unstructured meshes. These capabilities include:

•Simple input parameters for producing an initial mesh

•Mesh refinement with a user-defined point, radius and mesh size multiplier

•Inclusion of features on the cylinder head, by placing a mesh line on important details and thus improving cell quality in these areas

•Additional input parameters for greater control over the mesh generation

The steps necessary to set up the tutorial are summarised below:

1.Importing the geometry surface

2.Modifying special cell sets in the geometry

3.Modeling the valve

4.Creating the automatic 2D template

5.Refining the 2D template around the injector

6.Adding features to the automatic 2D template

7.Using additional parameters for detailed control of the automatic 2D template creation

As a prerequisite, it is recommended that you complete Chapter 3 of this volume to familiarize yourself with the es-ice facilities for importing the engine geometry and modelling valves.

Importing the Geometry Surface

To import the geometry surface mesh:

•Launch es-ice in the usual manner

•In the Select panel, click Read Data

•In the Read Tool, click the ellipsis (...) next to the DBase box and select geometry.dbs via the file browser

•Click the ellipsis (...) next to the Get box and select 1 Surface via the database browser

•In the Plot Tool, click CPlot

The engine geometry surface will appear in the Geometry window as shown in Figure 10-1

Figure 10-1 Geometry window: Imported geometry surface

Defining Special Cell Sets in the Geometry

In the following steps, you will use the supplied training user panel to issue the appropriate commands instead of typing them into es-ice (see Chapter 2, “User panels” in the User Guide volume).

To open the training panel:

•From the menu bar, select Panels > Directory

•Enter the directory location of the supplied user panel (training.pnl)

•From the menu bar, select Panels > training

Next, you need to modify three special, numbered cell sets that identify certain key surfaces on the geometry.

•Enter the following command to isolate the cylinder cells, as shown in Figure 10-2

CSet, Newset, Type, Cursor

Figure 10-2 Cylinder shell selection

•In the training panel, click Cylinder Shells to save the cylinder wall shells to

CSet 1

•Repeat the previous steps to save the piston shells to Piston Shells and the entire trimming surface to Trimming Shells, as shown in Figure 10-3 and Figure 10-4.

•Note that the trimming shells include all the geometry surface shells and line cells but do not include the valves (these are modelled in the next section).

Figure 10-3 Piston shell selection

Figure 10-4 Trimming shell selection

Modelling the Valves

Generally, valve modelling in es-ice determines the valve shape and the direction of valve motion. For the automatic 2D template, this step defines a ring of vertices on the valve diameter that facilitate the valve motion.

To model the valves:

•Enter the following command to collect all geometry shells into the current CSet

CSet, All

•Make sure the Geometry window is active and then choose a more suitable viewpoint by entering:

View, 0, 0, 1

•In the Select panel, click Create Template

•In the Create Template panel, click Valve profile

•In the Create valve profile panel, ensure that Valve 1 is selected from the drop-down menu and the Coordinate system is set to 11

•Click Select and then pick the Valve 1 surface shells (+x, +y quadrant) in the Geometry window, as shown in Figure 10-5.

Figure 10-5 Selecting Valve 1

•Click Create profile

•Repeat the previous steps for Valve 2 (-x, +y quadrant), Valve 3 (-x, -y quadrant), and Valve 4 (+x, -y quadrant). In each case, make sure you select Valve 2, Valve 3 and Valve 4 from the drop-down menu in the Create valve profile panel.

Creating valve profiles generates a spline representing the calculated shape of the