High Inlet Relative Mach Number Centrifugal Compressor Impeller Design

This document presents an overview of impeller inlet relative Mach number, how the parameter is calculated, and its importance as an indicator of impeller performance. Comments are also offered regarding the comparison of inlet relative Mach numbers obtained from different compressor vendors. A sample impeller is used to illustrate the various methods used to calculate the inlet relative Mach number. Test data for that impeller is also offered to indicate the performance map achievable with high Mach number designs. Please note that this document is not intended to be an all-inclusive treatment of the subject; rather, it summarizes the OEM’s methodologies and perspective.