NORA Tables

You can locate the tables on the Siemens Support Center at: .

When a version is selected in the Major Releases panel, the Simcenter STAR-CCM+ Application Specific Solutions folder appears on the left side, in which you can find the In-Cylinder_EmissionLibraries_NORA.tar.gz archive. Both NORA tables are stored within this archive.

NORA library for H2

The main reasons to use the H2 NORA library are the following:

• The enthalpy level of H2 is very different from conventional fuel and the NORA tables have been generated as a function of enthalpy and not unburnt temperature to take into account heat losses. The scaled enthalpy, evaluated for H2, is wrong if the minimum and maximum enthalpy values are taken from the NORA auxiliary library generated for C7H16.
• Comparing H2 and C7H16, the same mixture fraction yields a significantly different equivalence ratio value. With equilibrium species being very sensitive to equivalence ratio, and fuel mixture fraction previously being used as an input in the C7H16 NORA library, the correct equivalence ratio values are now used instead.
• NOx equilibrium values can be quite different for H2 compared to C7H16.

NORA Table

NORA tables contain information about relaxation times and the equilibrium fuel mass fractions of NO, NO2, and N2O. These values are used to calculate the source terms for each of the NOx species.

Properties

Save Table in .sim File

When activated, stores the NORA table in the sim file. When deactivated, the NORA table is not stored in the .sim file—which is useful to save disk space when using the same NORA table in different .sim files, or when auto-saving many sim files. If the NORA table is required for future use, you must export it manually by right-clicking the NORA table node and selecting Export Table. Then save it separately from the .sim file.

Path for Table Read

Specifies the file path location of the NORA table file that has been exported from Simcenter STAR-CCM+ and saved previously. Useful to reduce the .sim file size and save disk space when several .sim files use the same NORA table.

Displayed Library

Specifies which of the three available tables is displayed:

Auxiliary Library	Typically, this library contains enthalpy bounds that are involved in the Equilibrium Library and the Relaxation Time library.
Equilibrium Library	Contains the equilibrium mass fractions of NO, NO2 and N2O.
Relaxation Time	Contains the relaxation times—the times required for different values of NOx mass fractions to return to their equilibrium values.

Context Menu

Import Table

Adds the NORA table.

Delete Table

Removes the NORA definition.

Final Table Grid Size

When a NORA table is loaded, the independent variables that are included within the NORA table are listed as sub-nodes, each displaying a read-only value for the number of grid points in the NORA table.

Right-Click Actions

Edit

The variables that are displayed are read-only.

Refresh

Refreshes the list of variables—for example, after deleting and reloading a new NORA table.

NORA XY Plots

Properties

The NORA table XY plots share some of the properties of the regular XY plots, with the addition of the properties that are described below. See Plot Properties Reference

X-Axis Variable

Allows you to select from the grid resolution variables that are available which is used for the X-axis. For example, Egr^2, Log(Pressure [bar]), Log(Zf), Normalized Enthalpy, Zf Segregation Factor.

Child Nodes

See:

• Data Series: Managing Data in a Plot
• Axes: Axis Properties Reference
• Legend: Legend Properties Reference

Right-Click Actions

New Plot

Creates an XY Plot which allows you to visualize the variable that you select from the stored NORA table—appears as a [Variable] child node.

Displayed Library	XY plots available to specify
Equilibrium Library	YNOEQ Chemical equilibrium mass fraction of NO. YNO2EQ Chemical equilibrium mass fraction of NO2. YN2OEQ Chemical equilibrium mass fraction of N2O.
Auxiliary Library	HMIN Minimum table enthalpy. HMAX Maximum table enthalpy.
Relaxation Time Library	TAU[1–18] The relaxation times in log format.