Comparison of synthetic and steady air jets for impingement heat transfer over vertical surfaces

Abstract

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Natural convection air cooling is the method of choice for many low-power electronics applications due to cost, availability, and reliability considerations. This method is not only limited to low-power applications, but is also constrained by the buoyancy dependence of the flow. Therefore, further enhancement of natural convection is needed. Enhanced natural convection allows higher heat dissipation while maintaining the simplicity of passive cooling. Synthetic jet devices operating on the microfluidics principle provide unique cooling advantages for local cooling with high coefficients of performance. Synthetic jets used in the current study are piezoelectrically driven, small-scale, pulsating devices capable of producing highly turbulent jets formed by periodic entrainment and expulsion of the fluid through an orifice. The compactness of the jet actuator coupled with the high exit air velocities can significantly reduce the size of thermal management systems. In this paper, we present experimental results for impingement heat transfer for both steady and unsteady jets over a Reynolds number range of 100 to 3,000. A range of nozzle-to-plate surface distances is discussed. To mimic a comparable electronics component, we used a 25.4-mm square heated surface.GE Corporat

Synthetic Jets for Heat Transfer Augmentation in Microelectronics Systems

“…In this study, the computational domain is presented in Figure 5, synthetic jets had a fundamental frequency of around 600 Hz, where the disk displacement and the exit velocity reach their peak values. They were capable of producing periodic jet streams with peak velocities in excess of 20 times the air velocities caused by comparable size conventional fans [23]. Any further increase in the frequency has expected to result in reduced cooling efficiency and increased power consumption.…”

“…This method is not only limited to low-power applications, but is also constrained by the buoyancy dependence of the flow. With the recent advancements in electronics technology leading to thinner, lighter, faster, and higher functionality products [23,24], significant heat dissipation in tight thermal real estate becomes unavoidable. A number of innovative cooling techniques [25,26] for low-cost, compact, and reliable systems have been considered and the demand for more powerful cooling systems, however, has led engineers to look for unconventional methods that further expand the limits of natural air cooling.…”

Model assessment of synthetic jets for turbulent combustion experiments

“…Unlike traditional jets, synthetic jets move fluid via periodically oscillating diaphragms that are contained within a wall-recessed cavity and eject fluid through a narrowed opening into the chamber (Smith and Swift 2003). Thus, synthetic jets result in high fluid ejection velocities with net-zero mass flux, driven by a significant momentum fluxattractive features for several applications encompassing power electronics cooling (Mahalingam and Glezer 2004;Arik et al 2012;He et al 2015), aerodynamics (Hassan and JanakiRam 1998;McCormick 2000), microfluidic devices (Mautner 2004) and granular flows (Han et al 2020), among others. Turbulent premixing for combustion is one possible extension of synthetic jets, and we assess their technical viability as turbulence generation devices in a hypothetical 4,189-cm 3 CVCC using computational fluid dynamics (CFD) modeling.…”