時系列3次元界面形状データを用いた分散相追跡手法の検討

Study on dispersed phase tracking method for time series 3-dimensional interface data

堀口 直樹   ; 山村 聡太*; 吉田 啓之  ; 阿部 豊*

Horiguchi, Naoki; Yamamura, Sota*; Yoshida, Hiroyuki; Abe, Yutaka*

多相熱流動を解明するため時系列かつ2次元または3次元における界面形状データを取得可能な詳細計測手法が開発されている。例えば、燃料冷却材相互作用における溶融燃料ジェットの微粒化物といった分散相の詳細計測が実施され、3次元空間におけるその粒径等の時系列データの取得が達せられているが、個々の分散相を追跡する手法がないことから、3次元速度データの取得には至っていない。本報では、時系列3次元データを用いた分散相追跡手法の検討結果を報告する。本手法の適用性の確認には、TPFITを用いた詳細二相流動シミュレーションにより取得した3次元空間における分散相の体積率分布と速度分布データを用いた。結果として、分散相について時刻間の体積率分布の相関を取ることで速度を評価できることを確認した。

Specific measurement methods have been developed to understand multi-phase thermal-hydraulic behavior. By using these methods, we can obtain time series two and 3-dimensional spatial interface data of phases. These data are useful for providing validation data for advanced simulation methods based on multi-fluid computation fluid dynamics. For example, to understand FCI (fuel coolant interaction) behavior, specific measurements for fragments (dispersed phase) generated from the jet were measured, and interface and size of fragments were successfully evaluated. However, 3-dimensional data for velocity was not assessed, because there is no tracking method for individual dispersed phases like a tracking method of PTV (particle tracking velocimetry), which using time series 2-dimensional data. In this paper, we developed the dispersoid phase tracking method based on time series 3-dimensional interface data. To check the applicability of this method for 3-dimensional interface data, we used detailed two-phase simulation data by using TPFIT. In these data, there are 3-dimensional data of both interface and velocity distribution. Then, we can evaluate the correct dispersed phase velocity, and we can consider the accuracy of the developed method precisely. In this paper, we applied the developed method to simplified two-phase flow. The simplified flow means not to include coalescence and fragmentation of dispersoids. As a result, the tracking of one dispersoid performed successfully, but a standard deviation of the measuring error increased with the decrease of cell number of the dispersoid.