摘要：At Siemens, an in-house CFD （computational fluid dynamics） code UniFlow is used 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. This paper outlines its physical models and numerical solution methods. Furthermore, for oil-immersed transformers, it presents an application to a HV （high voltage） winding in a traction transformer of locomotives, cooled by synthetic ester.