The fluid–structure interaction between a tensioned elastica and a flotation guide

Abstract

Fluid–structure interaction between a flotation-guide and a tensioned elastic beam was investigated theoretically and experimentally. The work is inspired by manufacturing of thin flexible materials such as paper, foils and tape, collectively known as web. The mechanics of the web was modeled as an elastica beam, and solved in a Eulerian reference system by using the finite element method. The fluid mechanics in the beam/flotation-guide interface was modeled with two different fluid mechanics approaches with and without height averaging of the flow variables. The fluid models were solved with a finite volume approach. A stacked, iterative coupling algorithm was used to obtain coupled solutions. Experiments were performed to verify the two FSI models. The experiments showed that the supply pressure inside the flotation-guide must be at least equal to the belt-wrap pressure of the web for flotation to occur, as expected. The effects of large web deformations and using the height-averaged fluid model were analyzed by varying design parameters such as web wrap angle, flotation-guide radius, supply pressure, and the distribution of the pressure supply holes. This work showed that the height-averaged fluid mechanics model fails to predict the two-dimensional flow near the exit regions, which develops for cases where the web-reverser clearance tends to have large diverging variations. It was also shown that in order to keep the applied web tension at a constant level, the arc length of the web between the supports must change.