Vortex Dynamics of Synthetic Jets: A Computational and Experimental Investigation

Seamless advancements in electronics industry resulted in high performance computing. These innovations lead to smaller electronics systems with higher heat fluxes than ever. However, shrinking nature of real estate for thermal management has created a need for more effective and compact cooling solutions. Novel cooling techniques have been of interest to solve the demand. One such technology that functions with the principle of creating vortex rings is called synthetic jets. The jets are meso-scale devices operating as zero-net-mass-flux principle by ingesting and ejection of high velocity working fluid from a single opening. These devices produce periodic jet streams, which may have peak velocities over 20 times greater than conventional, comparable size fan velocities. Those jets enhance heat transfer in both natural and forced convection significantly over bare and extended surfaces. Recognizing the heat transfer physics over surfaces require a fundamental understanding of the flow physics caused by micro fluid motion. A comprehensive computational and experimental study has been performed to understand the flow physics of a synthetic jet. Computational study has been performed via Fluent commercial software, while the experimental study has been performed by using Laser Doppler Anemometry. Since synthetic jets are typical sine-wave excited between 20 and 60 V range, they have an orifice peak velocity of over 60 m/s, resulting in a Reynolds number of 2000. CFD predictions on the vortex dipole location fall within 10% of the experimental measurement uncertainty band.