Source of the default Specific Speed for pumps and turbines

Applies To 
Product(s): HAMMER
Version(s): CONNECT Edition, V8i
Area:  Modeling
Original Author: Jesse Dringoli, Bentley Technical Support Group


In the Transient tab of a pump definition, there are several default selections available for Specific Speed. What is the source of the 4-quadrant characteristic curves behind these specific speeds?

Also - what is the source of the curves behind the default Specific Speeds for turbines



For Pumps, the specific speeds 25, 94 and 145 (SI units) were derived from data published by Stepanoff (1957), as well as personal correspondance, in terms of relative Q and N along lines of constant head and torque throughout the entire operating range.

The other default specific speeds are from Thorley, A.R.D and A. Chaudry., "Pump Characteristics for Transient Flow Analysis", Department of Mechnical Engineering & Aeronautics, City University, London ECIV OHB


For turbines, the specific speeds 115, 170 and 230 (SI units) are from published data from the US Bureau of Reclamation (USBR).

See Also

Estimating the Specific Speed of a Pump or Turbine