Host: The Japan Society of Mechanical Engineers
Name : Dynamics and Design Conference 2019
Date : August 27, 2019 - August 30, 2019
The self-excited vibrations of a pipe conveying fluid have been studied as a typical example of the unstable vibrations in continuous mechanical systems. When the flow velocity exceeds a certain value, a certain mode on the pipe vibration becomes unstable and the post flutter phenomena become a problem. When a lumped mass is attached at the lower end, Copeland and Moon clarified from the visual inspection in experiments that a clamped cantilevered pipe exhibits some kinds of non-planar complex motions. From their pioneering experimental study, it has been well known that a large end mass enriches the dynamics of pipe conveying fluid. In this study, we conduct the series of experiments of self-excited vibrations in cantilevered pipes that are hung vertically and have end masses. The experiments are conducted to capture the complex non-planar motions using the end mass and the flow velocity as the control parameters. We conduct the measurements of pipe displacements in three dimensional spaces by the image processing system. The image processing system enables us to conduct the non-contact measurements at 200 frames per second. From the quantitative measurements of pipe vibrations, we confirmed some kinds of pipe motions i.e. planar pipe vibration, non-planar rotational vibration, rotating planar vibration.
