Fibre behaviour in the spunbonding process. Part I: Characterisation of air flow and fibre motion in the diffuser

The random fibre oscillatory behaviour induced by turbulence in the diffuser of an industrial spunbonding rig is measured experimentally. The turbulent air flow is firstly characterised by constant temperature hot-wire anemometry: averaged flow quantities, such as the mean velocity and the turbulent kinetic energy, as well as time dependent quantities, such as the integral time and the energy spectrum, are measured. The influence of the turbulent flow on the dynamics of a nylon fibre of diameter 200 mu m and a spunbonding fibre of diameter 18 mu m in the diffuser is then investigated by extracting the transverse displacement from images acquired by a digital camera.