Numerical Analysis of Gas Core Length Prediction in a Steady Free Surface Vortex

None

堺 公明; 江口 譲*; 岩崎 隆*; 大島 宏之; 山口 彰

Sakai, Takaaki; Eguchi, Yuzuru*; Iwasaki, Takashi*; Ohshima, Hiroyuki; Yamaguchi, Akira

数値解析によるガス巻込み評価の可能性を検討するため、定常くぼみ渦のガスコア長さ予測に関する数値解析を実施した。3次元数値解析結果に伸長渦理論を適用して予測したガスコア長さについて既往試験データと比較するとともに、ガス巻込みの発生とガスコア長さの関係について評価した。その結果、数値解析によるガス巻込み評価について見通しが得られた。

Design method to prevent the gas entrainment from a steady vortex in a cylinder is discussed. The gas core length of the surface vortex dimple is used as a measure of the criterion of the gas entrainment. Burgers vortex model is applied compensationally to predict the gas core length with the practical CFD method. Practical CFD method that did not consider the liquid surface deformation was validated. Macroscopic flow parameters predicted by the CFD method showed reasonable agreements with the measured data in a cylindrical tank. In addition, predicted gas core lengths by using the CFD results showed conservatively longer length than the measured data. The criterion of the gas core length to prevent the gas entrainment was tried to evaluate for the Baum data in order to see the prospects of the design method. In conclusion, it may say that the CFD method has a possibility to evaluate the gas entrainment from a surface vortex.