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

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

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.