Hello, I am working on my final project to the school. I've chosen a simulation of turbocharger by Garrett. I tried couple of settings but I think the results are not right and I would like to get some advice from experienced users.

I would like to be able to make a compressor map like this https://www.garrettmotion.com/wp-content/uploads/2018/05/Comp-Map-GT-2860R.jpg 

First setting: 

Inlet: enviromental pressure

outlet: outlet volume flow

I used this tutorial https://hawkridgesys.com/blog/solidworks-turbocharger 

Problem of this setting: I could not get mass flow rate more than 20 lb/min and the pressure ration was decreasing with increasing outlet volume flow.

I read that the outlet volume flow is not a good idea but I do not know how to setup a boundary conditions to get a right data. As a output I should be able to get pressure ratio (outlet/inlet) and mass flow rate. I should be able to make a compressor map from link https://www.garrettmotion.com/wp-content/uploads/2018/05/Comp-Map-GT-2860R.jpg 

Thank you very much.