Water Hammer in Horizontal Water-Steam Counter-Current Flow

A six-equation, one-dimensional, two-fluid model of the two-phase flow, incorporated into the recently developed computer code WAHA, was used to model water hammer transient initiated with liquid-vapor counter-current flow in the horizontal pipe. The applied flow regimes and closure relations of the WAHA code for the inter-phase exchange of mass, momentum and energy are described and discussed. Although the WAHA code flow regime maps turned out to be sufficient and accurate for simulations of the column separation type of the fast transients, the current analysis pointed out the need to introduce some limiting values for dispersed flow regime correlations in order to successfully simulate water hammer initiated by condensation-induced counter-current flow. The WAHA code with modified relaxation source terms was then successfully utilized for simulations of the experiments performed at the Hungarian PMK-2 test facility.