Forced convection heat transfer enhancement in heat sink channels using aeroelastically fluttering reeds

Abstract

Heat transport within rectangular, mm-scale channels of forced convection heat sinks is enhanced by the aeroelastic fluttering of cantilevered planar thin-film reeds protruding into the channels. The shedding of a train of counter-rotating vortical structures induced by the motion of the reeds and their effects on heat transfer from the channel walls are investigated in two separate testbeds. The interaction of the reeds with the cross flow in the channels is investigated in a single channel model using PIV with specific emphasis on the formation, shedding, and advection of small-scale vorticity concentrations that lead to enhanced mixing of the core flow and enhanced dissipation reminiscent of a fully-developed turbulent channel flow. Heat transfer enhancement is investigated using a pair of back-to-back heat sinks with a common heater that model the fins of an air-cooled condenser. It is demonstrated that the power dissipation and temperature in the heat sink base flow can be matched at reduced air flow rate with the addition of the reeds (for example, between Re = 1,000 baseline and 775 with reeds). The reduction in the required air volume flow rate indicates the potential for lower system-level losses of the cooling air flow and consequently significant reductions in the cooling power.