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COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Drag reduction with polymer addition in Taylor-Couette flow with Taylor instabilities
Submission Author:
Ivanor Martins da Silva , ES , Brazil
Co-Authors:
Edson Soares, Renato Siqueira, Rafhael M Andrade, Ivanor Martins da Silva
Presenter: Ivanor Martins da Silva
doi://10.26678/ABCM.COBEM2017.COB17-2406
Abstract
Drag Reduction (DR) in turbulent flow by adding small amounts of high molecular weight polymer is an important phenomenon, which has been studied for almost 70 years. This phenomenon occurs with the interaction between polymer macromolecules and turbulent vortices. However, over time, the same processes cause the breakdown of molecules, decreasing DR efficiency. Unlike the great majority of the researches in this area, which studies DR in the turbulent regime, the present work analyzes experimentally the drag reduction in the transition region between the laminar regime (absence of vortices) and the fully turbulent regime (chaotic vortices), in the space between two concentric cylinders installed in a rheometer, where the outer cylinder is fixed and the inner cylinder rotates (Taylor- Couette flow). The fluid used here is a solution of polyacrylamide (PAM) in deionized water, with the concentrations of 10, 30, 50, 100 and 400 ppm. The experiments carried out here show that the reduction of drag does not occur only in the presence of turbulent vortices (as some studies claim), but they are also perceptible in the transition region (Taylor instabilities). It is observed in the transition regime that DR increases with the polymer concentration and also with the Reynolds number, however, there is almost no degradation of the polymer in that region.
Keywords
drag reduction, Taylor-Couette flow, Taylor instabilities
