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32.3.8 Define/Models/Species/Autoignition...

The Define/Models/Species/Autoignition menu item opens the Autoignition Model panel. See Chapter  19 for details.



Autoignition Model Panel


The Autoignition Model panel allows you to set the parameters related to the Knock Model or the Ignition Delay Model.

If Species Transport is selected in the Species Model panel, turn on Volumetric under Reactions. With this model selected, only the Ignition Delay Model can be enabled.

figure

Controls

Model   contains options to disable or enable models.
Off   disables the model.

Knock Model   enables the knock model. With the Premixed Combustion or Partially Premixed Combustion models selected, only the Knock Model can be turned on.

Ignition Delay Model   enables the ignition delay model.

Options   contains two correlation options that exist with each model.
Douaud   option is used for knock in spark ignition engines. The modeling parameters that are specified in the GUI for this option are the Pre Exponential, Pressure Exponent, Activation Temperature, Octane Number, and Octane Exponent (Equation  19.2-2).

Generalized   enables generalized correlation described by Equation  19.2-3. It requires the same parameters as in the ignition delay model.

Hardenburg   enables Hardenburg correlation, which is used for heavy-duty diesel engines. This option is activated only for the ignition delay model.

Model Prameters   contains parameters related to the selected model.
See Section  19.2.3 for the details about the parameters in this panel.
Fuel Species   lists the available species.

Pre-Exponential   see Equation  19.2-3 and Equation  19.2-2.

Activation Temperature   see Equation  19.2-2).

Pressure Exponent   see Equation  19.2-3 and Equation  19.2-2.

Octane Number   see Equation  19.2-3 and Equation  19.2-2.

Octane Number Exponent   see Equation  19.2-3 and Equation  19.2-2).

Activation Energy   see Equation  19.2-3 and Equation  19.2-5.

Temperature Exponent   see Equation  19.2-3.

RPM Exponent   see Equation  19.2-3.

Equivalence Ratio Exponent   see Equation  19.2-3.

figure

Options   contains two correlation options that exist with this model.

Douaud   enables Douaud correlation (Equation  19.2-2) used for knock in SI engines.

Generalized   option (Equation  19.2-3) in the knock model require the same parameters as in the ignition delay model.


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