[prashanth_kasarla]

I am new to CFX.
I am working on centrifugal compressor for small turbojet engines.
I created the geometry using bladegen, meshed it in turbogrid(only one blade with periodic boundary). 1.5 million cells.
geometry has three domains: 1.Inlet 2. Impeller 3. outlet
inlet and outlet are stationary and impeller is rotating at 43250 RPM.
interfaces are connected using frozen rotor.
It is a steady state problem. Total energy including viscous dissipation is used. ideal gas.
Inlet boundary conditions are Stagnation pressure and Stagnation temperature.
Outlet - mass flow or static pressure.
I need to plot performance of compressor for different mass flow rates.
From basic calculations the design exit pressure is 400 kpa. so, I varied exit pressure from (200 kpa-380 kpa) from results it is observed that mass flow is almost constant around(5.2 kg/sec) . After 380 kpa solution is not converging below 10^-3 and mass flow is observed to be very low(0.75 kg/sec).
I tried with mass outlet boundary condition(4.2-5 kg/sec) - but this is having converging issues. I cannot find what is problem with mass flow boundary condition at exit.

In Solver control advanced options,compressible control and High speed numerics is switched on.

please help me with this problem i am working on this for past 1 month.
thanks in advance

[turbo]

Beyond 380kPa, your compressor approaches stall.