Pressure drop in two-phase swirling flow in a steam separator

Pressure drop and liquid film thickness in air-water swirling flows in a one-fifth scale model of the steam separator are measured for a wide range of gas and liquid volume fluxes. Numerical simulations based on one-dimensional single-fluid and two-fluid models are also carried out to examine the feasibility of predicting the pressure drop and film thickness in swirling flows. The pressure drop in a single-phase swirling flow is about five times as large as that in a non-swirling flow due to the increase in the frictional pressure drop. The pressure gradient and liquid film thickness in a two-phase swirling annular flow at the inlet of the pick-off-ring of the separator are well evaluated by using a standard one-dimensional two-fluid model, provided that the interfacial and wall frictions in an ordinary two-phase annular flow are multiplied by appropriate constant values. (author)