Chapter 6 STAR SET-UP in es-ice

The model at the beginning of this chapter can be resumed from file: save_es-ice.3-starsetup

The following tutorial data files are used in this chapter:

TRIMMING_TUTORIALS/manifold.dbs

TRIMMING_TUTORIALS/cylinder-3600.dat

TRIMMING_TUTORIALS/intake-3600.dat

TRIMMING_TUTORIALS/exhaust-3600.dat

The model at the end of this chapter is saved to file: save_es-ice.4-final

es-ice is designed to set up and run moving mesh problems for engine simulation as quickly and efficiently as possible. For this reason, the Star Controls panel (initially implemented in es-ice version 2.00) is designed to minimise the additional information needed to set-up a CFD analysis via the pro-STAR interface.

The Star Controls panel will supply the following items:

•Modifications to valve lift profiles

•Further changes to Star Setup parameters (Engine RPM, Start (deg), Stop (deg))

•Modifications to cylinder compression ratio

•Addition of static meshes to the initially generated mesh (e.g. manifolds)

•Combustion model data, in particular:

•Fuel type

•Model calibration parameters

•Ignition timing and location

•Knock and soot models

•Initial conditions for the cylinder and ports:

•Velocity

•Pressure

•Temperature

•Turbulence

•Gas composition

•Boundary conditions for individual cylinder and port boundaries:

•Adiabatic, fixed and mapped temperature walls

•Flow rate

•Pressure

•Temperature

•Turbulence

•Gas composition

•Post-processing set-up

•Time step controls

•Special files needed for importing the model into pro-STAR

Load Model

The Load model view loads the model into the Controls Workspace window.

•Click Load model on the left of the Star Controls panel (see Figure 6-1)

•Click Load model

Figure 6-1 Star Controls panel: Load model view

Analysis Set-up

The Analysis setup view is used to specify preliminary combustion model settings and parameters that define the initial scalar composition. The mass fractions of these scalars are calculated when you go through the “Write Data” section at the end of this chapter.

To complete the Analysis setup stage for this tutorial:

•Click Analysis setup on the left of the Star Controls panel (see Figure 6-2)

•Check that the Combustion toggle button is selected so that you can include a combustion model in the problem set-up

•Set the combustion model to ECFM-3Z, spark

•Set the fuel type to n-octane / iso-octane and Premixed

•Set the Mixture option to Phi and enter 1.3 for the air-fuel ratio

•Set the EGR definition to Air+Exhaust and enter 5% in the adjacent box to specify that 5% of the intake charge is recirculated exhaust gas

Figure 6-2 Star Controls panel: Analysis setup view

Valve Lifts

The Valve lifts view allows you to shift and modify the valve lift profile using anchors and multipliers. You can also adjust some of the Star Setup parameters and the compression ratio.

In this tutorial, no changes are required as the vlift01.dat and vlift02.dat files initially imported into the model in Chapter 4 are correctly set up.

To display the relevant data via the Valve lifts view:

•Click Valve lifts on the left of the Star Controls panel, as shown in Figure 6-3

Figure 6-3 Star Controls panel: Valve lifts view

Assembly

The Assembly view allows you to add static meshes, such as manifolds and replacement ports, that need to be included in the overall model. In the following steps, you will add static meshes representing the intake and exhaust manifolds:

•Click Assembly on the left of the Star Controls panel (see Figure 6-4)

•Click the ellipsis (...) next to Database file and select manifold.dbs via the file browser

•Click the ellipsis (...) next to Database ID and select 1 Intake Manifold via the database browser

•Click Get to load the intake manifold into the Controls Workspace window

•Click the ellipsis (...) next to Database ID and select 2 Exhaust Manifold via the database browser

•Click Get to load the exhaust manifold into the Controls Workspace window

The es-ice output window will display the following commands:

IceTemplate, Controls, Pieces, DBRead, "manifold.dbs", 1

IceTemplate, Controls, Pieces, DBRead, "manifold.dbs", 2

These commands indicate that the intake manifold cells have been read into es-ice.

Figure 6-4 Star Controls panel: Assembly view

If you wish to perform additional mesh-change operations on any other part, use the General Workspace window. After making the required changes, click Load to load the current cell set from the General Workspace into the Controls Workspace window. All cells in the Controls Workspace window will form the version of the mesh that can be imported into pro-STAR.

After the two manifolds are imported into the Controls Workspace window, create cell couples joining the ports to the manifolds:

•In the Plot Tool, deselect the Fill toggle button

•With the Controls Workspace window active, enter the following commands

CSet, All

CPlot

•In the Star Controls panel, select the Partial toggle button

•This option permits coupling of part of the intake manifold to the intake port (see Figure 6-5)

•Click CP Match

•In the Controls Workspace window, click an interior face, as shown in Figure 6-5

Interior Face

Figure 6-5 Creating cell couples

es-ice temporarily creates patches, then cell couples and then plots the new cell connectivity. If the cell couples are incorrectly defined, you can undo the coupling by clicking Undo. Note that the interior faces between these two bodies will disappear after you have successfully created the cell couples.

Continue to couple the manifolds to the ports as follows:

•In the Star Controls panel, deselect the Partial toggle button and click CP

Match

•In the Controls Workspace window, pick an interior face between the exhaust port and exhaust manifold

•In the Star Controls panel, click CP Transform to transform cells containing master/slave coupled cell faces into polyhedral cells

•CP Transform deletes the cell couples and replaces them with one-to-one connections between cell faces, as shown in Figure 6-6.

•Click Finish to finish defining cell connectivity and pro-STAR moving-mesh “events”