Dynamic analysis of small pigs in space pipelines

Abstract

This paper deals with the dynamics of small pipeline inspection gauges (pigs) in space pipelines. First, the differential equations for dynamic analysis of the small pig, whose length is short, are developed. The flow field can significantly influence the pig's trajectory. In this research, the effect of the flow field on the pig's trajectory was ignored. The path of the pig or centerline of the pipeline is assumed to be a curve in 3D space. Next, the differential equations of motion are combined and reduced to only one nonlinear differential equation with respect to the parameter of the space curve. The fourth-order Runge-Kutta method is then used for solving the equation. The driving force is assumed to be time-dependent, but the coefficient of friction is assumed to be constant for the sake of simplicity. The simulation results show that the derived equations are effective for estimating the position and velocity of the pig and forces acting on it at all time instants of its motion. © 2008 Institut français du pétrole.