NUMERICAL-CALCULATION OF TURBULENT-FLOW IN A PLANAR BIFURCATION WITH A PROTRUDING BRANCHING DUCT

This study presents numerical predictions on the fluid flow and heat t ransfer characteristics of turbulent flow in a planar bifurcation with a protruding branching duct. A nonorthogonal body-fitted coordinate s ystem and multiblock subdomain were used to handle the complexity of t he geometry, and a control-volume-based finite difference method was e mployed to solve the governing equations. The parameters studied inclu de mass flow rate of the branching duct (beta = 0.2, 0.8), protrusions (a = 0 H/8), inclined branching angle (theta = 90 degrees 80 degrees ), and entrance Reynolds numbers of the main duct (Re = 8000 16,000 an d 24,000). The results of numerical calculations show that there are t wo recirculation regions in the flow field, one on the bottom wall of the main duct and the other on the upward stream of the branching dud at the mass flow rate of the branching duct beta = 0.8. There is one s mall recirculation region on the upper wall of the main duct near the corner of the protruding branch theta = 90 degrees in the case with pr otruding branching duct. The results of numerical predictions also sho w that the turbulent flow field of the branching duet and pressure dro p are strongly influenced by the mass flow rate of the branching duct end the extent of the branching duct protrusion. In addition, numerica l predictions of the heat transfer effect show that the maximum local Nusselt number on the wall of the branching duct with beta = 08 is abo ut 2.5 rimes that of beta = 0.2 for the same Reynolds number. When the mass flow rate of the branching duct beta = 08, with or without branc hing duct protrusion, the local Nusselt numbers on the bottom wad of t he main duct drop rapidly at X/H congruent to 3.7.