A numerical investigation of the thermal and hydrodynamic behaviors of a channel with rectangular pin fins in aligned and staggered configurations

Abstract

A finite volume approach is used to numerically study the thermal behavior and pressure drop in a channel with pin fins of square cross sections. A steady, and laminar air flow, with uniform temperature profile, approaches the pin fin array with constant velocity. The pin fins are stacked in two different configurations, staggered and aligned. The fin walls are simulated as impermeable, no-slip boundaries with isothermal boundary condition. Two different S * values are used, with S * being the ratio of the minimum space between two adjacent fin walls to the diameter of the fin. Various approaching velocities are used in order to assess the dependence of the thermal and hydrodynamic behaviors on Reynolds number. In the aligned configuration, the numerically calculated fin Nusselt number showed a maximum average value at the first row of the array. It then decayed in the streamwise direction with increasing row number. This behavior is consistently observed for all Reynolds number values and for both spacing ratios. A similar behavior is observed in the staggered configuration with row one and two showing comparable average fin Nusselt number as Reynolds number is increased. This is attributed to the flow field acceleration due to the area confinement presented by the fins in the first row of the array. The average fin Nusselt number decay with the streamwise direction is shown to be a function of stacking configuration, Reynolds number and dimensionless ratio, S * . The distribution of the fin pressure coefficient, C p , showed two distinct regions; a developing region close to the channel inlet and a fully developed one further downstream. The thermal to hydrodynamic ratio of the fin array decreased with increasing row number, N. At fixed S * values, a better performance is observed in the cases corresponding to the staggered configuration in the rows close to the channel inlet. Arrays with large spacing ratios, S*, showed better performances than small spacing ratio fin arrays. Aligned fin arrays, with large spacing ratio, showed the best thermal to hydrodynamic ratio.