Two-phase flow pressure drop in right angle bends

Gas-liquid two-phase bubbly flows in right angle bends have been studied. N umerical predictions of the flow in right angle bends are made from first p rinciples using an Eulerian-Eulerian two-fluid model. The flow geometry inc ludes a sufficiently long inlet duct section to assure fully; developed flo w conditions into the bend. The strong flow: stratification encountered in these flows warrant the use of Eulerian-Eulerian description of the flow, a nd may have implications for flow boiling in U-bends. The computational mod el includes the finer details associated with turbulence behavior and a rob ust void fraction algorithm necessary for the prediction of such a flow. Th e flow in the bend is strongly affected by: the centrifugal forces, and res ults in large void fractions at the inner parr of the bend. Numerical predi ctions of pressure drop for the flow with different bend radii and duct asp ect ratios are presented, and are in general agreement with data in the lit erature. Measurements of pressure drop for an air-water bubbly flow in a be nd with a nondimensional bend radius of 5.5 have also been performed, and t hese pressure drop measurements also substantiate the computations describe d above. In addition to the global pressure drop for the bend the pressure variations across the cross section of the duct that give rise to the fluid migration (due to centrifugal forces), and stratification of the phases ar e interesting in their own right.