Help setting up combustor problem

Tom

Hello all,

I'm modeling a simple combustor and have problems with setting up the initial conditions. The combustor operates on natural gas. The compressor pressure ratio is 2 and mass flow is 0.30 kg/s. Air velocity entering the combustor is calculated to be approx 65 m/s and fuel velocity from nozzles is 80 m/s. Excess air is 600%. The problem is that when I set up 65 m/s as inlet air velocity, once converged, the absolute pressure at inlet is less than 202 650 Pa (about 130 000 Pa), but I think the pressure at inlet should not change. Pressure losses in the combustor are about 3%. I'm not sure what I should use as operating pressure, maybe this is causing the problem. Does anyone have experience with combustor modeling? Any help would greatly be appreciated.

Tom