Development of identification method of unsteady gas entrainment vortex; Evaluation of three dimensional behavior of free vortex by identification of vortex center line

Matsushita, Kentaro ; Ezure, Toshiki ; Imai, Yasutomo*; Fujisaki, Tatsuya*; Tanaka, Masaaki  

In safety design of sodium-cooled fast reactor, generation of a cover gas entrainment vortex at free surface in upper plenum is an issue. It is necessary to evaluate gas entrainment vortex by numerical analysis, and gas entrainment amount evaluation tool "Stream Viewer" based on velocity distribution obtained by numerical analysis is developed. In this report, as a part of the development of Stream Viewer, evaluation method to identify vortex center line from free surface is examined to evaluate three dimensional behavior of gas entrainment vortex. The evaluation method was applied to an open channel water test in which an wake vortex is generated unsteadily from the plate. It was confirmed that vortex center line can be identified and a vortex that propagates to downstream and gas core grows can be distinguished from a vortex in which gas core does not grow by evaluation method of the vortex center line.