Analytical and Experimental Analysis of Friction Forces inside Curved Pipes

Abstract

Abstract In-pipe robots are a powerful tool for hydrate plug removal inside ultra-deep water pipes. These robots may operate with energy supplied by umbilical cables immersed in oil. Present work focus on the development of a general strategy for computing the required forces for pulling such cables confined in ducts of generic length and geometry. Based on mathematical models obtained from specialized literature, a computational algorithm was designed to evaluate the static friction force related to the cumulative effects along the arbitrary set of curves present in a generic pipe. This computational routine can calculate the static friction forces associated to a cable inside a given pipe, whose coordinates are fed by the user. To evaluate the simulation performance, the achieved results were compared with that ones obtained through experimental tests performed using a cable with polymeric coating positioned inside ducts. Different geometries, load and lubricating conditions were tested, and the analytical model could estimate with reasonable accuracy the required force to move an umbilical cable inside pipes.