Transient response for different support of pipes with flowing medium subjected to impulse loading

Abstract

The primary aim of this study is to investigate the effects of a flowing medium on the transient response for different types of pipes subjected to dynamically applied loading. The types of support include a cantilever pipe, encastre pipe, propped cantilever pipe, and simply supported pipe. The topic is very important in many industrial and military applications including offshore structures, oil and gas, power stations, petrochemical and defence industries where critical pipe components transporting a gas or liquid can be subjected to impact loading due to an accident. In many previous studies, such effects were largely ignored, simplified or considered negligible. The conducted study demonstrated that in many practically important cases, the influence of flowing medium on transient response is not small and has to be taken into consideration. The classical Bernoulli-Euler beam theory is adopted to describe the dynamic behaviour of an elastic pipe and a new governing equation of a long pipe transporting gas or liquid is derived. This governing equation incorporates the effects of inertia, centrifugal and Coriolis forces due to the flowing medium. This equation can be normalised to demonstrate that only two non-dimensional parameters govern the static and dynamic response of the system incorporating a pipe and flowing medium. The transient response of this system is investigated based on a standard perturbation approach. Further, a numerical method utilising the finite difference method is developed and applied to investigate the dynamic response of pipes with different support. It is demonstrated that the previous dynamic models which largely ignore the internal flow effects and interactions between the flow and structure normally produce a large error and are inapplicable to the analysis of many practical situations.