Help for setting 3D boundary condition in compressing water vapor
 

Dear all here,
I am a beginner to simulate 3D single stage axial compressor compressing water vapor under vacuum but got some difficulties with the boundary condition setting.

Known values I have are, compressor inlet total pressure (970Pa), mass flow rate, inlet total temperature and compressor's geometric size, blade rotating rpm. What I want to calculate out is, outlet total pressure, temperature. When I am using Fluent for the calculation, I have some points not clear:

1) should I set operating pressure to be 0? I understand the absolute pressure would be added based on this operating pressure and if I put 0 in operating pressure but put gauge pressure in inlet gauge pressure, it should be fine, am my understanding right?

2) I set inlet as mass flow rate, according to my understand to gauge pressure, I put the total inlet pressure value into initial gauge pressure, is it right?

3) I am not sure how to set up outlet, outlet pressure might be right choice, but I have little idea what I should do with the gauge pressure, should it be the static pressure as the same value as inlet?

4) To make pressure convergence, should I set pressure desensitization as standard mode?

Could some one here give me some advise? that would be highly appreciated.
BTW, the flow would be sub-sonic.
Thanks advance.