No abstract

No abstract

No abstract

Abstract: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.

At Siemens the in-house CFD code UniFlow is used to analyse fluid flow and heat transfer in oilimmersed and dry-type transformers, as well as transformer components like windings, cores, tank walls, and radiators. It can be employed to perform steady state as well as transient analyses. This paper describes its physical models and numerical solution methods. Moreover, it presents an application to a valve winding of a HVDC transformer, cooled by mineral oil. This study is aimed at finding the flow induced pressure loss in the winding and the static ring assembly below and above the winding. The investigation includes isothermal runs with different inlet velocity and a conjugate heat transfer run with a conductor representation. In the isothermal simulations a steady state is established and the pressure loss is an almost linear function of the inlet velocity. In the run involving heat transfer, the high buoyancy forces hamper the development of a steady state and the possibility to calculate a flow induced pressure loss.