The specific speed (Ns) of a turbine is defined as the speed of a geometrical turbine that develops unit power (P) when working under a unit head (H) and is given by:
1
Ns = \(\rm\frac{N \sqrt{H}}{P^{5 / 4}}\)
2
Ns = \(\rm\frac{N \sqrt{P}}{\sqrt{H}}\)
3
Ns = \(\rm\frac{N P}{H^{5 / 4}}\)
4
Ns = \(\rm\frac{N \sqrt{P}}{H^{5 / 4}}\)