Heat Transfer From Interrupted Plates

Abstract

The forced convection heat transfer from two plates aligned with the flow direction in a wind tunnel was measured. The effects of leading edge bluntness, plate spacing distance, and Reynolds number on the leading and trailing plate average heat transfer rate were studied. The low Reynolds number, steady laminar and transitional flow regimes investigated are typical for compact heat exchangers. The measured heat transfer rate from the leading plate agrees well with laminar theory for thin plates when the leading edge is rounded. The heat transfer rate from the leading plate with a blunt nose ranges from slightly below theoretical at a Reynolds number which gives a long, steady separation bubble to well above theoretical under conditions of laminar separation and turbulent reattachment. The heat transfer rate from the second plate is influenced by the leading edge configuration of the first plate only at small plate spacing distances and high Reynolds number. At large spacings the mixing provided by the unsteady wake of the first plate dominates that due to the turbulence formed by leading edge separation on the first plate. The leading edge configuration of the second plate is important only at large values of plate spacing. The heat transfer rate from the second plate is generally higher than that predicted by theory for laminar, steady flow over thin plates and may be higher than that on the leading plate.