Countercurrent Flooding in Pipes Containing Multiple Elbows and an Orifice

Abstract

Flooding in three piping systems containing multiple elbows and an orifice was experimentally investigated using a 51mm glass pipe and an air/water system. The vertical-to-horizontal geometry with multiple horizontal sections connected by 90°elbows yielded the most limiting flooding gas velocities due to the prolonged formation of the hydraulic jump caused by the added hydraulic resistance of the multiple elbows. Inclining one of the piping sections downward to 45°from the horizontal or to the vertical in the other two geometries eliminated the hydraulic-jump-induced flooding mechanism and increased the flooding gas velocities for the system at high liquid flow rates. The orifice placed in the horizontal section was seen to generally lower flooding gas velocities, with the greatest effect seen for the smallest orifice tested. A new method based on a superposition principle was also proposed for prediction of flooding in complex piping systems.