How can I simulate CO combution process in chamber which walls are water cooled? How can I define mixture of gases and reactions insie chamber and pure water stream inside walls? please help regards p.s I use Fluent soft.

The best way to setup the problem would be to first model the combustion chamber with multiphase flow and combustion inside.To satisfy the boundary condition define some sort of heat flux BC on the boundary based on a staandard heat transfer coefficient and once you have success with this add the water cooled walls