LAUSR

Abstract Recurrence analysis of pressure signals measured from the pipe wall simultaneously with flow visualization is used to depict a methodology for identifying intermittent flow sub-regimes through opaque pipes. Pressure signal alone is not sufficient to differentiate two-phase flow regimes in an opaque pipe. Hence, the phase space trajectory of pressure signals is used to develop a recurrence plot for each sub-regime. It is observed that a homogeneously dispersed type of recurrence plot is obtained for plug flow which changes to a checkerboard-like structure for the slug flow pattern. This depicts the chaotic nature of slug flow. The chaos increases with further increase in gas superficial Reynolds number when aeration in slug flow enhances, leading to highly aerated slug flow. It is established that the recurrence plot and recurrence quantification parameters change as the flow transits from plug to less aerated slug and highly aerated slug regime. Thus the recurrence analysis of pressure signals has shown potentials to be used as a technique to identify different intermittent flow sub-regimes.