Computational investigation of flow and thermal characteristics of the rotor of large air-cooled turbo generators

Abstract

The present paper deals with an investigation of and thermal characteristics of the rotor of large air generators. The auto-circulated cooling system of the rotor is analyzed and flow characteristic of the cooling system is obtained. Thermal resistances and different losses are calculated complex geometry of the rotor is modeled using finite difference method by considering uniform nodes along the rotor body and rotor conductors. Then by employing a combination of line iterative method and the direct method, temperature distribution at different parts and convection coefficient in the airgap and radial subslots are evaluated. Results show that the flow convection coefficient are directly dependent upon the slots which have a dominant role on the cooling effect of the air. In addition, about 8 degrees of air temperature rise is reported as the air flows through the subslot. Furthermore, the air is subjected to approximately 25 degrees of temperature rise as passes from subslot to airgap through radial subslots. results are in good agreement with the available factory data.