Ravikiran Sangras

The phenomenon of argon gas entrainment into primary sodium in the hot pool of a liquid Sodium cooled Fast Reactor (SFR) is investigated. A combined experimental and computational approach is proposed. Physical entrainment of argon into sodium is highly geometry dependent and the present study is focused on the Indian Prototype Fast Breeder Reactor (PFBR). The computational model which is used for parametric studies is validated against a 1/4 scale water model tests. Based on systematic experiments, the free surface velocity for onset of gas entrainment is determined to be 0.32 m/s, and the corresponding threshold value for the surface vorticity has been estimated as 8.3 s -1. A horizontal baffle plate attached to inner vessel is found to reduce the free surface velocity/vorticity effectively. The radial width of the baffle plate and its elevation has been optimized to be 0.125 m and 0.315 m from free surface by computational studies. The optimized device has been tested in the water model to confirm its satisfactory performance before its recommendation for PFBR. © 2013 Elsevier B.V.

The effect of the small scale turbulence on the development of the round jet is experimentally studied using hot wire anemometry. The small scale turbulence is generated by placing a grid having grid spacing near the nozzle exit. Experiments are carried out for the range of Reynolds numbers (4000, 6000 and 8000). It is observed that the small scale structures present in the jet slows down the jet mixing characteristics and there by retards the decay rate in the near-field region. It is observed that in the grid disturbed jets, the ratio of the turbulent kinetic energy to mean-flow kinetic energy is relatively lower than that of the undisturbed jet without any grid. From the spectral analysis, it is observed that the grid disturbed jets has higher energy content than that of the undisturbed jets. © 2013 by Walter de Gruyter Berlin Boston.