Identification of vortical flow pattern inside PWR fuel assembly

In this study, in order to examine the vortical flow structure inside fuel assembly with mixing vanes, simulations were conducted with the commercial CFD software, ANSYS CFX R.14. The predicted results were compared with the measured data from the MATiS-H test facility. Through these comparisons, it was concluded that although there were locally differences between the prediction and the measurement, ANSYS CFX R.14 could qualitatively predict the time averaged vortical flow inside fuel assembly with mixing vanes. Additionally either absolute helicity or Q-criterion could efficiently identify vortex core region in the subchannel. Vortical flow distributions inside fuel assembly were significantly different, depending on the arrangement pattern of the mixing vane. (authors)