Visualization of the underexpanded gas jet into water

Uchida, Mitsunori*; Someya, Satoshi*; Okamoto, Koji*; Ohshima, Hiroyuki

When a heat exchanger in a fast breeder reactor cracks, a sodium-water reaction occurs. Highly pressurized water or steam escapes into the surrounding liquid sodium. The release of steam into the liquid sodium media is a two-phase flow with an under expansion. Several studies have examined the under expansion of the gas-gas phase. However, there are few reports on the underexpansion of the gas-liquid phase. In this study quantitative measurement was carried out for the purpose of revealing the flow with the underexpanded gas jet injected into water. The gas jet distance and the expansion angle were then obtained from averaged images of a high-speed camera. The entrainment velocity and the velocity of the entrained water droplets were also obtained by PIV.