# Turbine specific speed

## Description

The specific speed value (radian/second) for a turbine is the speed of a geometrically similar turbine which would produce one unit of the specific speed of a turbine is given by the manufacturer (along with other ratings) and will always refer to the point of maximum efficiency.

Related formulas## Variables

n_{s} | Turbine specific speed (dimensionless) (dimensionless) |

n | Wheel speed (in rpm) (dimensionless) |

P | Power (in kW) (dimensionless) |

H | Water head (in m) (dimensionless) |