PIV measurements of the instantaneous velocities of flow in an annular duct

Particle image Velocimetry (PIV) is a well-established technique in the field of fluid flow measurement and provides instantaneous velocity fields over global domains. It has been applied to external and internal flows, in single and two-phase flows. Regarding internal flow, works about the application of PIV in annular ducts are scanty. An experimental work is presented, where flow of water is studied in an annular duct of inner diameter of 60 mm and outer diameter of 155 mm and 10.5-m length, with the goal of obtaining detailed velocity measurements. Experiments were also conducted in a 21.1-mm inner-diameter horizontal transparent pipe of 3m length for comparison purposes. Depending on the flow rates of water, it can be laminar, transitional or turbulent. In this study, the water flow rate was kept at two different values for the horizontal pipe, for either laminar or turbulent flow, and three different values for the annular duct, allowing the analysis of one laminar and two turbulent flows. Velocity fields and statistic quantities of the turbulent flow were calculated.