Numerical comparison between a reference and simplified two-phase flow models as applied to steam generator dynamics

An important issue in two-phase flow dynamics modelling remains to know how and how much as well as for what kind of dynamical conditions a computer model can be simplified to save computing time while keeping enough accuracy. In order to get insight in this issue, numerical experiments have been performed to compare computed results of a reference model with those of various simplified models. These comparisons are devoted to the transient behaviour of a steam generator of counter flow type with liquid sodium as primary heating fluid. The investigated transients are induced by rapid or slow variations (steps and ramps) of the boundary conditions, i.e. steam pressure, feedwater flow rate, inlet temperatures, etc. This paper presents a review of results and conclusions. Numerical rules are given on the validity of the investigated simplifications, which should facilitate the selection of an adequate model for a given dynamical situation. (author)