For the compressor maps for automotive turbochargers, the Corrected mass flow rate (at inlet) is given as abscissa. However, I wish to know the mass flow rate at the outlet. What is the relation in between them, given the Pressure ratio (2.5)
The mass flow across a turbocharger is constant:
If X kilogrammes of air go in then X kilogrammes of air come out.
However if the pressure is twice the inlet pressure then the output volume is smaller and the density is higher as well as the temperature is increased. This is one reason there are intercoolers as having too high an inlet temperature reduces the volumetric efficiency.
A good reference for the concepts and formulae you need is Engineering Thermodynamics, Work and Heat Transfer by Rogers & Mayhew (still have my original copy bought some 30 years ago).