Evaluating 43-inch generator rotor thermal behavior using computational fluid dynamics (cfd) techniques

摘要

This paper explains results of a computational fluid dynamics (CFD) analysis to evaluate ventilation and temperature fo rotors being modified to prevent cracking at ventilation holes. The analysis is an important element in one utility's management of an aging fleet of rotors. Much has been written about the structural considerations concerning axial vent hole cracking in certain generator rotors. This paper covers the analysis of ventilation and temperature changes resulting from modifications in end turn blocking and slot filler design. The results show the velocity, pressure and temperature distribution in the rotor with comparison of conditions before and after the modifications to address vent hole cracking. The 4-million cell CFD model takes into account heat conduction within the rotor, convection to the ventilating gas and the rise in temperature of the gas as it picks up heat from the rotor. The analysis was useful in improving the redesign to reduce both the hotspot and average temperautre of the rotor winding.