For pumps and compressors, matching the machine's performance curve to the system's frictional resistance prevents severe operating faults like choking or system surge. The Dangers of Surge, Choke, and Cavitation
Fluid shear forces acting on the non-bladed surfaces of rotating discs.
O. E. Baljé’s Turbomachines: A Guide to Design, Selection and Theory
The Cordier Diagram plots Specific Speed against Specific Diameter. By calculating the desired flow and head, engineers look up the optimum position on the Cordier curve to instantly determine whether an axial, radial, or mixed-flow layout will yield the highest operating efficiency. 5. Performance Limits and Aerodynamic Losses