An Eigenproblem Formulation for Heat Transfer Computation on Periodic Geometries

MARIO A. STORTI; JONATHAN DORELLA; LUCIANO GARELLI; GUSTAVO A. RÍOS RODRIGUEZ

Punta Arenas

Jornada; XVII Jornadas de Mecánica Computacional; 2018

Sociedad Chilena de Mecánica Computacional

Power transformers are one of the most valuable components in electrical power networks. During the electric conversion from high to low voltages, part of the energy is lost as heat in the windings and the core, which must be evacuated through the machine radiators. One way of enhancing the heat transfer is to promote a secondary flow that transports heat from the center of the channel to the wall by convection (a.k.a. introduction of ?axial vorticity?). The secondary flow can be produced by pasive devices known as Vortex Generators. If a detailed model of one VG requires 1 Mcell then the whole array would require at least 240 Mcells. This poses the problem if a well-posed, convergent computation on one representative cell (RVE=Representative Volume Element) can be solved in order to obtain the characteristic exchange rates of the exchanger. It is observed that the mean temperature field decays exponentially along the channel axis. It looks like that the temperature field is periodic but modulated with an exponential. A methodology for computing iteratively the decaying factor is presented in this work. Each iteration has the cost of solving a steady heat transfer problem with standard BCs, which is implemented in Code_Saturne multiphysics parallel code.