Effect of physical properties on gas entrainment rate from free surface by vortex, 2

Koizumi, Yasuo*; Ote, Naosuke*; Kamide, Hideki ; Ohno, Shuji  ; Ito, Kei

A sodium-cooled fast breeder reactor is now at the developing stage in Japan. One concern for safety is cover gas entrainment into the sodium coolant. The gas entrainment rate into liquid by the vortex formed on the free surface was examined experimentally. Four kinds of test fluid were used; water at 25C, water at 60 C, 20 cSt silicone oil and kerosene. The gas entrainment rate into liquid was measured. The relation between gas entrainment rate and liquid velocity was mainly affected by the viscosity of liquid. As viscosity became large, higher exit velocity was required to get the same gas entrainment rate. No systematic trend by the surface tension was noticed in the gas entrainment rate. A flow state at the outlet piping has significant effect on the gas entrainment rate. The dimension of the outlet piping may become important to consider the gas entrainment rate in the vortex type region.