Chapter 11	MULTIPLE-CYCLE ANALYSIS
	Setting Up Multiple Cycles in es-ice

Chapter 11 MULTIPLE-CYCLE ANALYSIS

The following tutorial model files are used in this chapter:

save_es-ice.3-starsetup (created in Chapter 4) save_ice

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

The tutorial in this chapter details the process of defining multiple cycles in an es-ice simulation. This process produces a .evn file for one engine cycle and then reuses the previously specified events for each additional cycle. The resulting advantage is a more efficient simulation set-up. Creating an ‘events’ file in pro-STAR can be time consuming due to the large number of commands that need to be executed. Also, covering more than one engine cycle in an events file uses an excessive amount of memory.

In this example, the model is set up to cover two full engine cycles, requiring a simulation over 1,440 degrees CA. The necessary steps are outlined below:

1.Specify the multiple-cycle parameters via the Star Setup panel

2.Continue the model set-up using the Star Controls panel, as illustrated in Chapter 6 of this volume

3.Finish the model set-up via the pro-STAR GUI, by specifying the simulation run time in the Run Time Controls panel

Setting Up Multiple Cycles in es-ice

The only action needed to define a multiple-cycle case is specification of the multiple-cycle parameter in the Star setup panel. The simulation duration, and hence the number of cycles covered, is defined when completing the model set-up in pro-STAR.

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Setting Up Multiple Cycles in pro-STAR

Start up es-ice and read in the model data:

•Make the directory containing the save_es-ice.3-starsetup file the current working directory

•Launch es-ice in the usual manner

•In the Select panel, click Read Data

•In the Read Tool, click the ellipsis (...) button next to the Resume file box

•Select model file (save_es-ice.3-starsetup) from the file browser. The model geometry appears in the Geometry panel.

To define the model as a multiple-cycle case:

•In the Select panel, click Star Setup

•In the Star setup panel, select the Multiple cycles toggle button

•Ensure that the Reset smoothers and Use Star controls toggle buttons are selected

•Select the latest pro-STAR version from the

drop-down menu at the bottom of the panel

• Click Star setup

When Star setup is complete, the model file can be saved.

•In the Write Tool, save the model as save_es-ice.multipleCycles

The next step is to specify the Star Controls parameters, described in Chapter 6 of this volume. When complete, continue with the next section of this chapter.

Setting Up Multiple Cycles in pro-STAR

The pro-STAR set-up for a multiple-cycle model is similar to that for single-cycle cases. The only exception is the Run Time Control parameters which are set to cover more than one engine cycle.

Start up pro-STAR and import the es-ice model.

•Launch pro-STAR in the usual manner

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	Setting Up Multiple Cycles in pro-STAR

•From the pro-STAR menu bar, select Panels > es-ice

•Click Resize. This will create a new param.prp file using MEMORY commands.

•Click Model. This will read in the model boundaries, cells, couples and vertices exported from es-ice. It will also read the initial and boundary conditions and set some model defaults.

•Click Events. This will create the necessary pro-STAR ‘events’. The result is a <casename>.evn file.

Next, set the analysis controls to use the recommended settings for a trimmed model.

•Go to panel Analysis Controls > Solution Method

•Set the Under Relaxation for Pressure Correction to 0.5, as shown in Figure 11-1

•Click Apply

Figure 11-1 Under-relaxation for pressure correction

Set the output control parameters as shown in Figure 11-2:

•Go to panel Analysis Controls > Analysis Output

•In the Post tab, set Output Frequency to 10 and Backup Frequency to 300

•Click Apply

•In the Transient tab, set the Starting at time (degCA) to 320 degrees CA and the Output interval (degCA) to 5 degrees CA

•Click Apply

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Figure 11-2 Post and transient analysis output settings

The run-time controls can now be set so as to cover two engine cycles, which equate to 1440 degrees CA. When the solver is running, the events file will be re-used at the start of the second cycle.

•Go to Analysis Preparation > Run Time Controls

• Check that Run time controls set to Run for

• Set Time (deg) to 1440 to cover two engine cycles

• Click Apply

Finally, write the geometry and problem files in the usual manner.

•From the pro-STAR menu bar, select

File > Save Geometry

•Set the Geometry Scale Factor to

0.001 to convert the model to mm

•Click Apply, followed by Close

• From the pro-STAR menu bar, select

File > Save Problem

•Click Save

The set-up in pro-STAR is now complete.

•Click Quit > Save & Quit to close pro-STAR

The solver can now be run, as described in Chapter 8 of this volume

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