Leak Orientation Effects on Flow-Induced Vibration in Horizontal Multiphase Pipelines

Abstract Multiphase pipe flow can result in strong structural vibrations. In this paper, an experimental investigation of the effects of leak orientation on flow-induced vibration in horizontal multiphase pipe flow is performed. Two leak orientations are investigated, a leak at the top of the pipe and a leak at the bottom of the pipe. Vibration signals are measured and high-speed videos are recorded. A total of four flow patterns including bubbly flow, plug flow, slug flow and stratified wavy flow are studied. Experimental results show that the leak orientation affects leak flow, leak flow rate, leak percentage and inlet flow rate in differing amounts depending on flow pattern. More pronounced changes are induced by a leak at the bottom of the pipe compared to a leak at the top of the pipe. Variance values of the extracted base functions are computed as a numerical indicator for the presence of a leak. A leak in bubbly flow is the easiest scenario to detect regardless of leak orientation. For a leak at the bottom of a pipe, differences in the computed variance values in plug and slug flows are comparable and detectable. A leak in plug flow induces a larger difference in the variance value than for slug flow if the leak is at the top of the pipe. Both leak orientations show difficulty in determining presence of a leak for stratified wavy flow. It is found that the differences in variance values computed using the x-axis (axial) accelerometer signal are smaller than the other two axes, indicating that more significant changes in FIV are induced in the radial and azimuthal directions during a leak event.