problem H2O and CO2 concentrations
 

Hi everybody.

I am doing a simulation of the Jet-A combustion. For that. i designed my own geometry, and i specified the requirements conditions in the combustion chamber. Everything seems to be well set up, but the mass concentrations profile which i get it doesn't make sense.

Enclosed you can find the mass concentration profile.

My doubts are: Why the H2O and CO2 mass fractions go up and down???? As far as i know, once the combustion takes place, the concentrations of the products are constant...

Due to that, I'm facing problems in pressure conditions and temperature inside of the combustion chamber, since the more the concentrations change, the more the volume change,and with that the pressure,temperature, velocity...

whether you know how i can solve this problem or explain me why this occur, i would really appreciate.