Post-Combustion CFD simulation in rocket nozzle
 

Hi guys,

i am trying so simulate a species transport problem through a convergent divergent nozzle with fluent. My fluid is a mixture out of H2O(vapor), OH, H, O, H2, O2.
I have the mass fraction of each specie after the combustion in a combustion chamber.

I defined a reaction mechanism with 14 Reactions. (Arrhenius Rate)
Ideal gas for density.
Polynomial cp for every species.

Pressure-Inlet:Gauge Total Pressure: 3e+6 Pa; Initial Pressure 2.9e6; total Temperatur of 3650 K

Pressure Outlet: 0 Pa
Operating Pressure: 0 Pa

I am using a density based, axissymmetric solver with species transport, EDC reaction and k-e-turbulence model.


My Problem, because im no chemical expert:
The mass fractions of each specie changes drastically after the first mesh node. I have an instant jump in every mass fraction and my Temperatur jumps from ~3600K to 4700K.
I think its because i have an very high inlet temperatur so the mixture is combusting after the first mesh node...
but how can i produce a mixture model, which isnt combusting? I mean the combustion should take place in the combustion chamber and i want to simulate the downstream condition with the in CEA calculated mass fractions.

i hope someone cann help me. if i should describe my problem more accurate plz tell me.

best regards

I am also stuck in the similar kind of problem. I want to model combustion gases through CD nozzle. I have only nozzle and external atmosphere around it in which pressure is 1000 Pa. Please help me in this regard.