Characteristic coefficient

In turbomachinery engineering, various characteristic coefficients are used to characterise operating behaviour and design type. These coefficients are derived from the physical quantities according to the affinity laws. The characteristic coefficients are dimensionless numbers used to perform the quantitative or qualitative evaluation of a condition.

Coefficients characterising the operating point

• φ    Flow coefficient
• ψ    Head coefficient
• λ     Performance coefficient
• Sr   Strouhal number 

Coefficients characterising different pump designs

• n_s  Specific speed