Interaction between Taylor bubbles rising in stagnant non-Newtonian fluids

• Tipo: Artigo em Revista Científica Internacional
• Data: 2007

Autores

R. G. Sousa (Autor) Outra; A. M. F. R. Pinto (Autor) FEUP; J. B. L. M. Campos (Autor) FEUP

Revista

Título: International Journal of Multiphase Flow

Vol. 33 Nº 9

Páginas: 970-986

ISSN: 0301-9322

Editora: Elsevier

Indexação

ISI Web of Knowledge - 27 Citações

ISI Web of Science

Scopus - 27 Citações

COMPENDEX

INSPEC

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia mecânica

CORDIS: Ciências Tecnológicas > Tecnologia

Outras Informações

ID Authenticus: P-004-7TF

DOI: 10.1016/j.ijmultiphaseflow.2007.03.009

Abstract (EN): The interaction between Taylor bubbles rising in stagnant non-Newtonian solutions was studied. Aqueous solutions of carboxymethy1cellulose (CMC) and polyacrylamide (PAA) polymers were used to study the effect of different theological properties: shear viscosity and viscoelasticity. The solutions studied covered a range of Reynolds numbers between 10 and 714, and Deborah numbers up to 14. The study was performed with pairs of Taylor bubbles rising in a vertical column (0.032 in internal diameter) filled with stagnant liquid. The velocities of the leading and trailing bubbles were measured by sets of laser diodes/photocells placed along the column. The velocity of the trailing bubble was analysed together with the liquid velocity profile in the wake of a single rising bubble (Particle Image Velocimetry data obtained from the literature). For the less concentrated CMC solutions, with moderate shear viscosity and low viscoclasticity, the interaction between Taylor bubbles was similar to that found in Newtonian fluids. For the most concentrated CMC solution, which has high shear viscosity and moderate viscoelasticity, a negative wake forms behind the Taylor bubbles, inhibiting coalescence since the bubbles maintain a minimum distance of about ID between them. For the PAA solutions, with moderate shear viscosity but higher viscoelasticity than the CMC solutions, longer wake lengths are seen, which are responsible for trailing bubble acceleration at greater distances from the leading bubble. Also in the PAA solutions, the long time needed for the fluid to recover its initial shear viscosity after the passage of the first bubble makes the fluid less resistant to the trailing bubble flow. Hence, the trailing bubble can travel at a higher velocity than the leading bubble, even at distances above 90D.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 17