The Effect of Curvature Radius and Reynolds Number on Laminar Flow Pressure Drop in Mini-180° Duct Bends

Pressure loss in mini duct bends did not receive a lot of researcher's attention, yet with the recent industry interest in mini and micro flow applications, it is necessary to address viscous flows in mini scale bends. This study numerically investigates the effect of curvature radius and Reynolds number on pressure drop in mini duct bends. The study addresses laminar flow in fixed cross-sectional area 180°duct bends with varying bend curvature radiuses and Reynold numbers. The results show that pressure drop is linearly related to bend curvature radius, while it has a nonlinear relation with Reynolds number. A pressure drop equation is proposed which introduces a curvature factor as a function of Reynold number and bend radius in the well-known Darcy-Weisbach equation. The results show less than 5% error in pressure drop using the presented curvature factor equation compared with the simulation results. On the other hand, the flow characteristics in the 180 bends are presented and discussed.