Numerical Study of Windage Power Loss for One Salient Pole Hydro Generator

In order to determine the impact of different rotor construction elements on windage losses, computational fluid dynamics study for one salient pole generator is performed. Fully predictive approach was employed to simulate air flow distribution through the machine for three different rotor configurations. Simulation results are compared with measurements and agreement of -1.2% for losses and -2.4% for flow rate were achieved. Analysis showed that between 84% and 90% of total windage loss can be attributed to two built-in centrifugal fans and poles that generate pressure required to establish necessary cooling air flow. Regardless of the rotor configuration, poles contribution to total windage losses is always significant and ranges from 29% to 80%. It has been shown that decrease of tangential velocity component in front of the inlet in interpolar space, dictated by the fan, can increase the poles losses regardless of the decrease of air flow rate through the interpolar space.