Experimental investigation of the stratified flow in the horizontal pipework of nuclear reactors Original Research Article

aboratory tests have been performed to study the behaviour of a stratified fluid flow in horizontal piping. Concentrated calcium chloride brine and fresh water at room temperature were used to model the density difference due to thermal effects in nuclear reactors. Flow phenomena relating to the interface and mixing of the two layers were observed through the plexiglass piping by means of a flow visualization technique involving a longitudinal laser beam section through the flow. The measurements have established that, at the representative flow conditions modelled by the experiments, despite the presence of strong surface waves on the interface, little mixing occurs between the two layers. Quantitative correlations for the depth of the interface between the two layers, its surface slope and the height of surface waves have been established by the definition and use of two dimensionless Froude numbers.