1997 Volume 25 Issue 2 Pages 89-98
Pressure characteristics were studied experimentally for a two cycle converging-diverging channel (a type of corrugated tube), using polyacrylamide water solutions as working fluids. Effects of the viscoelasticity on the pressure distribution along the channel wall were examined by comparing the data for polymer solutions with a Newtonian fluid. The experimental results for the two cycle channel were also compared with the data for one cycle channel having the same dimension. The total pressure drop for the two cycle channel with a dilute polymer solution was smaller than that of the Newtonian fluid in a region of lower Reynolds number, whereas no such a symptom was observed in the case of the one cycle channel.
From the observation by a flow visualization technique in the laminar flow regime, there were found to exist five and four major flow modes in the converging and diverging parts of the channels, respectively, and hence there appeared, in total, thirteen flow states in the channels. Based on the flow modes, flow state maps are presented in the present study.
