NUMERICAL PREDICTION OF LAMINAR-FLOW AND FORCED CONVECTIVE HEAT-TRANSFER IN A HELICAL SQUARE DUCT WITH A FINITE PITCH

Fully developed laminar forced convective heat transfer in helical squ are duels is studied numerically using a finite-volume method. The H1 thermal boundary condition is applied. Dean numbers up to 510 and Pran dtl numbers between 0.005 and 500 are considered. Correlations for the mean Nusselt number are proposed. For a toroidally curved duel, two s olution branches with a two-vortex secondary flow and one branch with a four-vortex flow are detected. The four-vortex solutions give, for h igh Pr, mean Nusselt numbers up to twice those of the two-vortex solut ions. For ducts of small pitcher torsion, the flow and heat transfer c haracteristics are similar to those of a toroidally curved duct with t he same dimensionless curvature epsilon. Copyright (C) 1996 Elsevier S cience Ltd.