Accelerated One-Phase Flow Through Perforated Plates

The coolant flow across the perforated dip-plate during a hypothetical core disruptive accident in a liquid-metal fast breeder reactor was simulated in a one-dimensional model. Several experiments with water as fluid and with various perforation ratios of the dip-plate and different initial heights of the fluid head over the dip-plate were run. The pressure drop across the dip-plate and the forces acting on the dipplate and on the upper plug of the reactor vessel were measured in a wide range of Reynolds and Strouhal numbers and of an acceleration parameter. The flow pattern downstream from the perforated plate was filmed with a high-speed camera. The resistance coefficients for the transient flow of the coolant through the perforated plate were obtained as a function of the acceleration. The forces acting on the upper plug and their time integral were compared with those acting on the dip-plate. Finally, using highspeed film pictures, the formation of fluid jets downstream from the dip-plate was investigated.