Coeficientes de perda de carga em válvulas e acessórios no escoamento de fluídos não-newtonianos puramente viscosos e viscoelásticos
Carregando...
Data
2003-07-29
Autores
Polizelli, Marcos Alexandre [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho foram obtidos coeficientes de perda de carga para válvulas e acessórios no escoamento de soluções aquosas modelo de bentonita, goma xantana e sacarose. Na determinação das propriedades reológicas das soluções foi usado um reômetro tipo Searle. Os dados experimentais foram ajustados aos modelos de Ostwald-de Waele, Bingham e Herschel-Bulkley, para as soluções consideradas puramente viscosas, e para a solução considerada viscoelástica foi ajustado o modelo de Carreau. Nos estudos de perda de carga foram usados os seguintes acessórios e válvulas: válvula borboleta com diferentes ângulos de abertura, válvula macho totalmente aberta e aberta pela metade, união e curvas de 180°, 90° e 45°. Todas as válvulas e acessórios são do tipo sanitário, construídos em aço inoxidável. O equipamento usado para as medidas experimentais de perda de carga foi calibrado previamente com etileno glicol. Para fluidos puramente viscosos, os coeficientes de perda de carga foram ajustados pelo método dos dois-ks, e para o fluido viscoelástico os mesmos coeficientes, foram ajustados a um modelo proposto neste trabalho. Os coeficientes de determinação, r2, para os ajustes ficaram entre 0,964 e 0,999 e, 0,636 e 0,997 para escoamento laminar e turbulento de fluidos puramente viscosos respectivamente e entre 0,804 e 0,999 para o fluido viscoelástico. O equipamento apresentou resultados experimentais melhores no regime laminar de escoamento.
In this work pressure drop coefficients were obtained in different fittings and valves in flow aqueous solution of bentonite, xanthan gum and sucrose. For the determination of rheological properties of the solutions a viscometer Searle was used. The experimental data were fitting to the Ostwald-de Waele, Bingham and Herschel-Bulkley models, for viscous fluids, and Carreau model for viscoelastic fluids. In the studies of friction losses the following fittings and valves were used: butterfly valve with different opening angles, plug valve totally opened and opened half, union and bends of 180°, 90° and 45°. All of the valves and fittings are of the sanitary type, manufactured in stainless steel. The apparatus used for the experimental measurements of pressure drop was previously calibrated with etileno glicol. The coefficients were adjusted by two-ks method, for purely viscous fluids, and by a proposed model in this work for viscoelastic fluid. The determination coefficients, r2, ranged from 0.964 to 0.999 and 0.636 to 0.997 for laminar and turbulent flow of viscous fluids, respectively, and from 0.804 to 0.999 for viscoelastic fluid. The apparatus and the calculus and fitting methods shown better performance to laminar flow.
In this work pressure drop coefficients were obtained in different fittings and valves in flow aqueous solution of bentonite, xanthan gum and sucrose. For the determination of rheological properties of the solutions a viscometer Searle was used. The experimental data were fitting to the Ostwald-de Waele, Bingham and Herschel-Bulkley models, for viscous fluids, and Carreau model for viscoelastic fluids. In the studies of friction losses the following fittings and valves were used: butterfly valve with different opening angles, plug valve totally opened and opened half, union and bends of 180°, 90° and 45°. All of the valves and fittings are of the sanitary type, manufactured in stainless steel. The apparatus used for the experimental measurements of pressure drop was previously calibrated with etileno glicol. The coefficients were adjusted by two-ks method, for purely viscous fluids, and by a proposed model in this work for viscoelastic fluid. The determination coefficients, r2, ranged from 0.964 to 0.999 and 0.636 to 0.997 for laminar and turbulent flow of viscous fluids, respectively, and from 0.804 to 0.999 for viscoelastic fluid. The apparatus and the calculus and fitting methods shown better performance to laminar flow.
Descrição
Palavras-chave
Mecanica dos fluidos, Reologia, Operações unitarias (Engenharia quimica), Operações unitárias - Perda de carga, Fluid mechanics
Como citar
POLIZELLI, Marcos Alexandre. Coeficientes de perda de carga em válvulas e acessórios no escoamento de fluídos não-newtonianos puramente viscosos e viscoelásticos. 2003. 94 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2003.