Experimental investigation of air–water turbulent swirling flow of relevance to phase separation equipment

Single and two-phase turbulent swirling flow inside a circular pipe in the presence of a conical bluff body is studied using high speed photography and laser-Doppler velocimetry. The geometrical configuration is relevant to liquid–gas separating equipment. Several flow regimes were identified and, in particular, the results show the presence of a spiral axial flow for low values of gas–liquid ratio (GLR). High speed photographs indicated that the flow consists of a gas core surrounded by a liquid annulus and forms a liquid–gas interface corrugations of capillary nature. The tip of the gas core becomes unstable and ejects gas bubbles in a spiraling stream. The velocity measurements indicated an increase of turbulent fluctuations in the liquid layer in the vicinity of the interface. The liquid layer maintained a Rankine vortex, while a weak forced vortex was obtained for higher GLR.