DRAG REDUCTION IN TURBULENT PIPE FLOWS WITH POLYMER-POLYMER MIXTURES

Gustavo Alonso Barrientos Sandoval¹; Edson José Soares¹; Fabricio Thomaz¹

¹ Universidade Federal do Espírito Santo

doi:10.20906/CPS/COB-2015-0352

Resumo

The turbulent drag reduction caused by polymer-polymer mixtures has been studied. Reynolds number was ranged from 7x104 to 1.1x105 and different concentrations were analyzed for flexible and rigid polymers. It is used an experimental apparatus compound by galvanized steel pipes which was thermally insulated. To minimize localized polymer degradation during the experiment, the solution was driven by aid of an air compressor, which is connecting pneumatically to a vessel that permits to fix the inlet pressure during the test. The inlet pressure was fixed in 250 kPa. The main results obtained are presented in terms of drag reduction as a function of the number of passes (Np) through the pipe line. The drag reduction is analyzed taking into account the friction factor of the polymeric solutions for each pass. Such a friction factor is compared with the solvent one (pure water) and drag reduction is calculated, as defined by Lumley (1969) Lumley (1969) DR=((1-f)⁄(f_0)) measured in the same Reynolds number. It was observed a synergy between these polymers mixtures. We believe that the aggregation in the mixtures is a possible cause of the observed synergy. This observation is very important from the industrial point of view, because the rigid polymer used in the present work is less expensive and is non-toxic.

Palavras-chave: Drag Reduction; polymer-polymer mixtures; turbulent flows; polymer concentration