Análise Experimental da Redução de Arraste Por Adição de Polímeros Rígidos em Escoamentos Turbulentos

Abstract

The drag reduction phenomenon (DR) by polimeric injection, surfactans and fibers in turbulent flow has studies and records that exceed sixty years and diverse applications such as firefighting, liquid transportation and even in the field of medicine. This work aims to deepen the studies on the mechanisms of operation of this phenomenon, acquiring information about a turbulent flow of water with polymer additive through smooth pipes. To and this, it was necessary to acquire the instantaneous velocity fields for each experimental test with the aid of the two-dimensional Particle Image Velocimetry (PIV) technique. Thus, it is possible to obtain the turbulent properties of each experiment and evaluate the polymeric influence. The tests were conducted for a Reynolds number range from 17.000 to 50.000 for water and from 19.500 to 40.000 for the polymeric solution. 200 ppm of Guar Gum were used in water. Flow with this additive shows a maximum drag reduction of around 30%, changes in the damping layer on the velocity profile close to the wall, increase in the RMS profile of axial fluctuations and reduction in radial. The Reynolds stress was shown to reduce with the polymeric addition.