non premixed combustion
 

i have simulate a not premixed combustion model for methane (ch4) and air.
using pdf model and k-e RNG for viscouse model.
temperature of fuel is 1112 k and air 600 k.
but combustion dosen't construct.
temperature of interaction doesn't increase and air & methane only mixed but doesn't interacted with each other.
what am i do?
thank you