MEASUREMENT OF LAMINAR VELOCITY PROFILES WITH NON-NEWTONIAN ADDITIVES USING PHOTOMICROSCOPY

摘要

This report describes the development of a photomicroscopic technique, using dark field microscopy, for the direct measurement of velocity distribution in an essentially one-dimensional channel. The method is particularly adapted to velocity measurements in close proximity to a frictional boundary, of the order of five microns.nVelocities are obtained from the analysis of light streaks, obtained from photomicrographs, due to the motion of illuminated polystyrene tracers, 0. 55 microns in diameter, dispersed in distilled water and aqueous solutions of a number of non-Newtonian additives.nVertical velocity distributions are obtained for the additives CMC, Polyox 301 and Polyhall 27, flowing in a lucite channel 13 mm. wide and 1. 5 mm in depth at concentrations of 1/8% and 1/4% by weight. Channel Reynolds No. was 0. 92.nThe results for distilled water indicate nearly perfect agreement with the theoretical parabolic velocity distribution for flow between parallel flat plates. The additives at both concentrations showed little variation from the velocity profile of the distilled water control except near the boundaries, from 0 to 100 microns, where the velocity was noticeably greater, in some cases by a factor of two.