[cfd user]

hi,
i am trying to model simple problem of hydrogen dispersion.
something like the model of methane and air model that exist in the tutorial guide of fluent. one inlet of air with slow velocity and small inlet of hydrogen with laminer velocity. the model is cyliner that open in the other side with outflow. i use traniset and laminer finite rate.
in fluent user guide that is a sentence that say:
"If you introduce fuel to an oxidant, spontaneous ignition does not occur unless the temperature of the mixture exceeds the activation energy threshold required to maintain combustion"

when i choose the temp of the inlet gas 300k there is ignition but it's not suppose to happen. spontaneous ignition suppose to happen in at least 500 k of hydrogen!

i hope someone can help
thank very much!!!