Numerical simulation of two-phase flow behavior under earthquake acceleration

地震加速度付加時の気液二相流解析

吉田 啓之  ; 高瀬 和之; 金子 暁子*; 文字 秀明*; 阿部 豊*

Yoshida, Hiroyuki; Takase, Kazuyuki; Kaneko, Akiko*; Monji, Hideaki*; Abe, Yutaka*

Fluctuation of void faction is an important factor for the safety operation of the nuclear reactor, and fluctuation of void fraction is related to behavior of gas-liquid two-phase flow. In case of the earthquake, the fluctuation is not caused by only the flow rate, but also body force on the two-phase flow and shear force through a pipe wall. Interactions of gas and liquid through their interface also act on the behavior of the two-phase flow. The fluctuation of the void fraction is not clear for such complicated situation under the earthquake. Therefore, the behavior of gas-liquid two-phase flow is investigated experimentally and numerically in a series of study. In this study, to develop the prediction technology of two-phase flow dynamics under earthquake acceleration, a detailed two-phase flow simulation code with an advanced interface tracking method TPFIT was expanded to simulate the two-phase flow under earthquake conditions. The bubbly flows in a horizontal pipe excited by oscillation acceleration and that under the fluctuation of the liquid flow were simulated by using the expanded TPFIT. In these numerical simulations, effect of the earthquake acceleration was added to bubbly flow through three different additional forces (inertia force, share force and body force). In the result, coalescence of bubbles, bubble shapes and bubble trajectories were affected by additional force that simulates earthquake acceleration.