The paper deals with the computer simulation of the Diesel fuel spray combu
stion under the similar conditions as in Diesel engines. A mathematical mod
el of the spray propulsion and combustion is treated which allows the obser
vation of the phenomena in the spray during its movement through air. Fuel
droplets of the spray are vaporized due to the transfer of heat from hot ai
r. In a certain moment when required conditions are met selfignition of mix
ture occurs. In order to determine the points where selfignitions occurs fi
rst, we have introduced the term "ignition probability" referring to the lo
cal air ratio and fuel dispersion in the spray.