Experimental investigation of the dynamics of slightly curved cantilevered pipes conveying fluid

The dynamics of slightly curvedcantilevered tubular beams conveying fluid was investigated experimentally. Apart from exhibiting a rich dynamical behaviour, interest in the matter arises mostly because in real-world applications pipes conveying fluid are often subject to geometric imperfections, rendering a straight pipe curved. A bench-top-size apparatus consisting of a reservoir and a hanging straight or curved clamped-free pipe conveying fluid was utilized. Four different cases were explored: (i) a water-discharging straight pipe in air (in the reservoir filled with air), (ii) a water-discharging curved pipe in air, (iii) an aspirating straight pipe submerged in quiescent water (in the reservoir filled with water), and (iv) an aspirating curved pipe submerged in quiescent water. Making use of a contactless optical technique, the displacement time-series signal was obtained and analysed to characterize the nature of the motions. It was found that curved cantilevered pipes conveying fluid display quite interesting nonlinear fluid-structure interaction dynamics. For initially curved discharging pipes, a large flow-induced static deformation materialized prior to the onset of an oscillatory instability. Aspirating curved pipes, on the other hand, are subjected to weak flutter superimposed on a static deformation.