Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
In this paper a method of temperature front measurement is proposed to quantify flow distribution within the cooling ducts of a power transformer winding. The winding will be prefilled with transformer oil at a certain temperature, and oil at another temperature pumped into the system. Velocities can then be estimated by keeping track of the oil temperature change in the oil ducts using temperature sensors. Due to the effect of buoyancy, the velocity field will not be constant during the temperature front measurement but with the help of transient CFD modeling the variation can be taken into account. The method has been successfully tested on a mock-up model of a transformer oil-guided disc winding section, and a comparison has been performed with steady state measurements using Laser Doppler Anemometry as well as both steady and unsteady CFD modeling results. Application of the temperature front method in real transformers will also be discussed.