The ignition delay time, 
, is a function of local conditions, namely the fuel,
pressure and temperature. You may either specify a custom correlation
by CEL or chose from the built-in empirical correlations.
The ignition delay time of gasoline can be modeled using the empirical correlation by Douaud and Eyzat [183]:
 | (7–107) |
where the octane number, 
, is a user input
parameter for the model. The correlation has been calibrated for the
octane number range 
.
The ignition delay time of Diesel fuel can be modeled using the empirical correlation by Hardenberg and Hase [185]:
 | (7–108) |
where
The user input parameters are the mean piston speed, 
, the engine velocity in rounds per minute, 
, and the cetane number of the fuel, 
. The apparent activation energy, 
, has been calibrated for cetane number
in the range 
.