[cheetthe1]

I am trying to set up a

combustor
followed by a converging section
followed by a relatively long straight pipe at near-sonic condition
followed by a dump/expansion region attached downstream.

The combustor is supposed to operate at pressure of 5atm, however I struggle to get the pressure set right. I am using mass flow inlets (conditions scaled so that they result in p=5atm) and pressure outlet (1atm) at the expansion region (external flow).

Any advice how to get the pressure set correctly? What happens upon initializing is that pressure builds up at the converging sections, leading to overall pressure build-up in the combustor beyond 5atm.

Thank you,
Bernie