Newisys Server Processor Cooling Augmentation Using Synthetic Jet Ejectors

This paper focuses on an implementation of synthetic jet ejectors for enhancing existing fan performance by controlling the bypass flow and imparting additional momentum to the flow. Synthetic or "zero-mass-flux" jets, unlike conventional jets, require no mass addition to the system, and thus provide means of efficiently directing airflow across a heated surface. Because these jets are zero net mass flux in nature and are comprised entirely of the ambient fluid, they can be conveniently integrated with the surfaces that require cooling without the need for complex plumbing. Wind tunnel tests are used to characterize the performance of an array of localized synthetic jets cooling two high density heat sinks in the presence of varying mean flows. The increased flow rate and heat dissipation due to the jets is measured. Results show that the percentage improvement in heat transfer due to the SynJets depends strongly on the relative flow rates of the SynJet and the mean flow. A NEWISYS server chassis was retrofitted with a synthetic jet module such that no changes to the mechanicals of the chassis were necessary. Two AMD processors in the server were stressed for high heat dissipation. It is shown that operating a synthetic jet in conjunction with a fan enables higher heat dissipation due to localized cooling by the synthetic jets without impeding the flow of the fan. The high momentum SynJets enable the entrainment of significantly higher flows and heat dissipation through the heat sink than the fan alone. It is also shown the adding the SynJets enables a reduction in fan RPM for equivalent thermal performance, thus resulting in significant reduction in the sound pressure levels.