Fluidic-driven cooling of electronic hardware. Part I: Channel integrated vibrating reed. Part II: Active heat sink

Enhanced heat transfer in electronic hardware by direct, small-scale actuation is investigated experimentally in two test bed configurations. In Part I of this work, a method for cooling compact electronics that exploits the unsteady motions induced by a vibrating reed embedded within a heated duct (in contact with hardware that needs cooling) to enhance forced convection transport heat from the duct surfaces is introduced. The time-harmonic oscillations of the PiezoElectric Reed (PER) induce a reverse Karman vortex street through the channel, introducing small scale motions throughout the length of the duct. The flow characteristics of this device are investigated with PIV for various reed operating conditions, including placing two reeds in tandem and in parallel. The effect of altering the channel configuration is also determined. For high heat flux applications, an externally induced bulk flow can be augmented by the small scale motions induced by the reed.;The small scale motions enhance the heat transfer over that of conventional time invariant flows at similar or higher Reynolds numbers. The vibrating reed helps to disrupt the thermal boundary layer as well as fully mix the heated fluid near the wall with the cooler core flow. In both the presence or absence of an externally induced core flow, streamwise distributions of local Nusselt number indicate that the heat transfer can increased by a factor of two.;In Part II of this work, the effect of small scale motions induced by a synthetic jet on heat transfer within an advanced heat sink is investigated. The synthetic jet module is optimized and several flow configurations are tested. The optimal design directs the synthetic jets to emanate directly through the base of the heat sink and induce a recirculating flow between the fins. This results in a lower thermal resistance than what is typically achieved with traditional fans at the same flow rate.