Experimental Modeling of Convection Downstream from an Electronic Package Row

Abstract

Experiments on convective heat transfer in the wake of a row of closely spaced pin-mount packages are reported. Flow visualization and interferometric heat transfer measurements are made in an induced draft wind tunnel where the package row is modeled with a two-dimensional transverse rib attached to one channel wall. The transverse rib has an aspect ratio of 5.25:1.0, and the channel height-to-rib height ratio is 4.0:1.0. Results are reported for coolant Reynolds numbers ranging from 1000 to 4000. Flow visualization shows the wake region to be similar to flow past a simple back step. Recirculating flow is found to extend from nine to three rib heights downstream from the rib, depending on the magnitude of the flow Reynolds number. Local heat transfer within this region is reduced relative to what would occur in the absence of the transverse rib, with average values of the heat transfer coefficient bracketed between laminar and turbulent correlations for simple back steps. Heat transfer rates further downstream, after reattachment of the flow, are in excess of those expected for flow with no transverse rib.