Measurement of gas entrainment rate from free surface by vortex

渦による自由液面からのガス巻込み流量の計測

小泉 安郎*; 大手 直介*; 上出 英樹 ; 大野 修司  ; 伊藤 啓

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

ナトリウム冷却高速炉における課題の1つであるガス巻込み現象について、渦による自由液面の巻込み流量を実験的に調査している。本研究では、作動流体を自らシリコンオイルに変更し、液位25mmでの実験を行った。その結果、渦状巻込みのみが観察され、また、可視化領域においてはほぼ環状流が形成された。また、シリコンオイルを用いた場合、水と比較してガス巻込み発生が抑制されること、流量に対するガス巻込み流量の増加割合が減少することがわかった。

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. In the present experiments, test fluid was changed from water in the previous experiments to 20 cSt silicone oil. The liquid level in the test vessel was 25 mm in the present experiments. Only the vortex-type gas-entrainment was observed as in the previous experiments since the liquid level was low. The flow state observed at the flow visualization section of the outlet pipe was only a semi-annular flow. The initiation of the gas entrainment was delayed in the case of silicone oil compared with the case of water. The increasing rate of the gas entrainment to the liquid velocity is milder in the case of silicone oil than in the case of water.