2.2. Energy transfer in region A
Analysis of the three regions can be performed by beginning with region A, where most of the useful work is done. Flow conditions at the boundaries of this most important and efficient region can then be used to define conditions for regions B and C. Fig. 11 shows the velocity diagram for the mean (mass averaged) streamline through the two stages of the impeller with terminology corresponding to Fig. 10. In the equations that follow, note that subscripts i and o refer to the inner and outer blade stations, respectively. The net ideal total pressure rise across the impeller is given by the first and second stage total pressure rise based on the Euler compressor equation