Derivation of the Torque—Speed Characteristic of a Reaction Turbine

Abstract

When a reaction turbine is coupled to a generator or when an electric motor is coupled to a pump, the torque–speed characteristic of the runner needs to be known so that the control engineer can analyse the system for stability and optimal operation. The currently used one-dimensional vector analysis applies only where there is smooth flow in the inlet of the machine. This paper modifies and extends this analysis to apply to a variable flow situation which occurs when the load on the machine is not equal to the optimal specified load. Runaway speed and starting torque of the machine can also be calculated using this analysis.