Abstract: Low Reynolds number forced convection heat transport within the fin channels enhanced by deliberate formation of unsteady, small-scale vortical motions using elastically fluttering thin-film reeds. The vortical motions substantially increase the local heat transfer coefficient at the channel walls and mixing between the wall thermal boundary layers and the cooler core flow. The flow mechanisms associated with production, advection and dissipation of these small-scale motions are investigated in a modular, high aspect ratio channel using micro-PIV, video imaging of the reed motion, and hot-wire anemometry. The global heat transfer enhancement in a modular heat sink prototype shows that the reed-induced small scale motions increase the turbulent kinetic energy of the flow even when the base flow undergoes transition to turbulence, leading to an increase in the local and global Nusselt number that is sustained at higher Re and a minor relative increase in losses.

Abstract: The present disclosure relates to a flow control system, comprising a controller, an ignition device whose activation is controlled by the controller, a combustion-driven jet actuator, and a fuel source in fluid communication with the jet actuator that supplies fuel to the jet actuator. Typically, the jet actuator comprises a combustion chamber, an orifice that serves as an outlet for combustion products emitted from the combustion chamber, and at least one inlet through which fuel is supplied to the chamber for combustion. In use, the combustion-based jet actuator can emit jets of fluid at predetermined frequencies.