Design of a pressure ratio 5 centrifual compressor

The designing study on a pressure ratio 5 centrifugal compressor has been done by the IDV numerical simulation for the entire flow field included impeller,diffuser and volute of the compressor.It shows that the study on transonic diffuser is the same important as the impeller,and a transonic diffuser would be chocked two times when the speed is been increased.The first choke has an important effects on the region of compressor mass flow;and the second choke would determined the limited loadness of impeller,so as the limited pressure ratio and speed of compressor.The chart map was obtained by IDV numerical simulation,which shows that the design point is in the high efficiency region,and stage efficiency is 0.85 at design point(pressure ratio 5.0,mass flow 2.0 m3/s),and the surge margin is up to 0.17.