Entrance Effects in Non-Newtonian Pipe Flow

[Abbreviated]

The prediction of the excess pressure loss accompanying the flow of a fluid through a sharp-edged contraction (from a large reservoir into a small tube) has been the subject or many theoretical analyses. Recent analyses have been concerned with a general "power law" non-Newtonian fluid. However, few experimental measurements, either of pressure losses or of velocity profiles, have been made, especially for non-Newtonian fluids.

In this investigation the entrance region pressure profiles were measured for an ethylene glycol-water solution, which was Newtonian, and for Carbopol-water gels of several concentrations, which were non-Newtonian. The flow was in the lamina regime with Reynolds numbers ranging from 100 to 1500.

The experimental results were reported in the form of an entrance correction to the Poiaeuille equation. An attempt was made to separate the upstream correction from the downstream correction, since the theoretical developments have ignored the upstream pressure effects.

[Abbreviated]

From this experimental investigation it was concluded that the pressure effects upstream from and immediately at the entrance, which have been neglected in the theory, are in fact significant, but that the downstream pressure effects are in reasonable agreement with the theoretical analyses.