Experimental study of air-water two-phase slug flow in horizontal pipe using high speed imaging

In the present study air-water two-phase slug flow in 220m horizontal pipe flow loop is investigated experimentally using high speed imaging and gamma densitometers. The aim of the study is to obtain insight into the local flow processes of slug development to characterize the dynamics of slug flow including the role of secondary flows, mixing, and entrainment across the multi-phase interface. Additionally, the influence of adding different surfactant concentrations on the slug flow is analysed. The superficial velocities of water and air range from UL=0.2 to 2.5 m/s and UG=0.2 to 2.5 m/s, in a 55mm inner diameter pipe. Measurements are performed for 28 different flow conditions of air and water phases. Additionally, the same measurements are repeated for two different surfactant concentrations. High quality images of slug flow are captured with a synchronized four high speed camera system allowing filming at a frame rate up to 5400fps on the maximum resolution. The optical section in the flow loop consists of a 2m long transparent acrylic correction box, positioned between the camera system and the LED light system. An image processing algorithm is developed to analyse slug flow characteristics (length, speed, and frequency) and the influence of surfactants on the slug flow behaviour including slug front stability. The results are validated with measurements from gamma densitometers.