Experimental Study on Helium-Air Exchange Flow Through Small Openings with Vertical Partition

The helium-air exchange flow may occur at the rupture accident of a standpipe in a high temperature engineering test reactor. A test vessel with three types of small opening is used for experiments. An estimation method of mass increment is applied to measure the exchange flow rate. Flow measurements are made with the single opening and partitioned, opening, for opening ratiosH 1/D 1 in the range 0.05 to 10, whereH 1 andD 1 are height and diameter of the opening, respectively. At lower opening ratios (H 1/D 1<0.75), the difference in the exchange flow rates between the opening systems is small. At higher opening ratios (H 1/D 1≥0.75), exchange flow rates of the partitioned opening system are higher than those of the single opening system because of separated (unidirectional) flows by partition. An effect of variation of diameters of the partitioned openings on the exchange flow rate is investigated. The exchange flow rate increases with the opening diameter. Finally, an experiment with two-opening is designed to investigate the effect of fluid interaction of the partitioned opening system. It is demonstrated that the exchange flow rate of the two-opening system is higher than that of the partitioned opening system because of the absence of the fluid interaction.