CFD SIMULATIONS OF OIL IMMERSED AND DRY TYPE TRANSFORMERS

Abstract

At Siemens the in-house CFD code UniFlow is employed to investigate fluid flow and heat transfer in oil immersed and dry type transformers as well as transformer components like windings, cores, tank walls, and radiators. We outline its physical models and numerical solution methods. As an oil transformer application of the method, the simulation of oil flow and heat transfer in 5 windings of a prototype transformer with ONAN/ONAF cooling mode is described. It corresponds to a heat run test with the total losses. Furthermore, we outline an application to an AFWF cast resin transformer prototype operated at ships in an enclosure. The ventilator driven air flow is cooled by sea water. In addition to the LV and HV windings the core is simulated. Here also the heat radiation makes a significant contribution to the heat transfer.