Specifying design point of a gas turbine: Lesson learnt.

1. Design point of the compressor for a gas turbine is specified at 100% RPM, 101325 Pascal inlet pressure and 288.15 at  0 Mach = ISA SLS
2. Design point performance of the compressor is specified as 3 numbers
1. Corrected mass flow rate
2. pressure ratio
3. efficiency
3. The inlet face of the compressor is at ISA SLS
4. If you have inlet pressure drop in the bell mouth inlet at ISA SLS, then actual mass flow rate seen by the compressor will be less than the corrected mass flow rate. 
5. For design point calculation, do not give inlet pressure drop in the bell mouth inlet.
6. If inlet pressure drop in the bell mouth inlet is zero, the actual mass flow rate and corrected mass flow rate will be same and it is easier to generate the compressor characteristics curve from CFD.  
7. Commercial softwares such as GSP change the design point Mach number automatically when you specify the inlet pressure drop. For example, if you give design point ISA SLS inlet pressure drop as 0.98, it will automatically raise Mach number to 0.17 and reduce the ambient temperature by 2 degrees. 
8. The raise in total pressure at the inlet due to Mach number compensates for the inlet pressure drop and the compressor corrected mass flow rate and actual mass flow rate are same. inlet face of compressor sees 101325 after the total pressure rise due to mach number and total pressure drop due to inlet pressure loss.
9. The reduction of ambient temperature by -2 degrees compensates for ram temperature rise and compressor inlet temperature  becomes 288.15 after Mach number total temperature rise 
10. If you want zero mach number with inlet pressure drop, use the "flight" option in GSP and not the design point calculation option.