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

Abstract

This study presents numerical predictions on Ike fluid flow and heat transfer characteristics of turbulent flow in a planar bifurcation with a protruding branching duct. A nonorthogonal body-fitted coordinate system and multiblock subdomain were used to handle the complexity of the geometry, and a control-volume-based finite difference method was employed to solve the governing equations. The parameters studied include mass flow rate of the branching duct (β = 0.2, 0.8), protrusions (a = 0, H / 8), inclined branching angle (θ = 90° 80°), and entrance Reynolds numbers of the main duct (Re = 8000, 16,000, and 24,000). The results of numerical calculations show that there are two 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 duct at the mass flow rate of the branching duct P = 0.8. There is one small recirculation region on the upper wall of the main duct near the corner of the protruding branch 0 = 90° in the case with protruding branching duct. The results of numerical predictions also show that the turbulent flow field of the branching duct and pressure drop are strongly influenced by the mass flow rate of the branching duct and the extent of the branching duct protrusion. In addition, numerical predictions of the heat transfer effect show that the maximum local Nusselt number on the wall of the branching duct with β = 0.8 is about 2.5 limes that of β = 0.2 for the same Reynolds number. When the mass flow rate of the branching duct β = 0.8, with or without branching duct protrusion, the load Nusselt numbers on the bottom wall of the main duct drop rapidly at X / H ≊ 3.7.

Notes

Address correspondence to Professor Yue-Tzu Yang, Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Republic of China.