Research on Wave Phenomena in Hydraulic Lines : 4th Report, Coupling between Oil Pulsation and Longitudinal Pipe Vibration

Abstract

The longitudinal vibration of a pipe caused by oil pulsation in it is investigated. The coupled vibrations of a pipe and oil are theoretically analyzed with the following assumptions : (1) Oil pulsation and pipe vibration are coupled only at the ends of a pipe, except where they are independent of each other. (2) The attenuation of pipe vibration results from the solid viscosity of pipe material. A viscoelastic model composed of a Voigt model and a series spring is introduced to represent the pipe vibration with damping. Another theoretical analysis considering distributed interactions through a pipe wall is also made and their significance is numerically estimated. The vibration tests of a straight steel pipe containing oil are carried out. The dynamic pressures of oil and the longitudinal accelerations of a pipe are measured and the obtained frequency characteristics are compared with the theoretical ones. The results support the validity of the analytical treatment developed here.