Coeficientes de perda de carga em valvulas e acessorios no escoamento laminar de fluidos nao-Newtonianos
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Data
2000-01-01
Autores
Telis-Romero, Javier [UNESP]
Gratao, Aha Carolina A [UNESP]
Garcia-Cruz, Crispin H. [UNESP]
Telis, Vania R N [UNESP]
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Resumo
Friction loss coefficients for laminar flow of xantan gum solutions (concentrations in the range of 0.1-0.5% by weight) through valves and fittings were experimentally determined. The rheological behavior, studied by means of a concentric cylinder rheometer, was pseudoplastic, being well described by the Ostwald-De Waele model with non-linear correlation coefficients (r) between 0.998 and 0.999. In the pressure drop measurements the following fittings were employed: completely open and half way open ball valve, completely open and half way open angle valve, tee used like coupling, tee used like a 90° elbow, short radius 90° elbow and coupling. The results showed that the friction loss coefficients increased with decreasing generalized Reynolds number. The friction loss coefficients could be well adjusted by a potential model, suggested by Kittredge & Rowley (1957) for Newtonian fluids, K f = A(Re g) -B, with correlation coefficients between 0.837 and 0.999.
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Palavras-chave
Correlation methods, Friction, Non Newtonian liquids, Pipe fittings, Pressure drop, Pressure measurement, Reynolds number, Rheology, Rheometers, Valves (mechanical), Concentric cylinder rheometers, Friction loss coefficients, Nonlinear correlation coefficients, Open ball valves, Xantan gum solutions, Laminar flow
Como citar
Ciencia and Engenharia/ Science and Engineering Journal, v. 9, n. 1, p. 78-82, 2000.