ISSN Online: 2377-424X
ISBN Print: 0-85295-345-3
International Heat Transfer Conference 10
NUMERICAL AND EXPERIMENTAL INVESTIGATION OF THE THERMAL CONVECTION FOR HERSCHEL-BULKLEY FLUID IN THE ENTRANCE REGION OF A DUCT
Résumé
The thermal convection, with constant heat flux
for non-Newtonian fluids in the entrance region of a duct
is studied theoretically and experimentally. In the
theoretical analysis it is assumed that: (i) the rheological
behavior of the fluid can be expressed through the
Herschel-Bulkley law: τ = τs + K γn; (ii) the now is
fully developed at the entry; (iii) all fluid properties,
other than consistency index are constant. The K-T
relation used is K = K0exp (−b T). Indeed in this analysis, viscous dissipation is taken into account. Velocity measurements for isothermal and heating situation, reveal the incidence of the imposed thermal field on the flow structure. It is characterized by an increase of shear rate at the wall, and of the size of the yield dimension. Temperature measurements permit the study of the local heat transfer. Finally, a correlation is proposed taking into account the modification of the wall shear rate
induced by the rheological properties and the temperature
dependent character of the fluid.