An Experimental and Computational Heat Transfer Study of Pulsating Jets

Abstract

Synthetic jets are meso or microscale fluidic devices, which operate on the “zero-net-mass-flux” principle. However, they impart a positive net momentum flux to the external environment and are able to produce the cooling effect of a fan sans its ducting, reliability issues, and oversized dimensions. The rate of heat removal from the thermal source is expected to depend on the location, orientation, strength, and shape of the jet. In the current study, we investigate the impact of jet location and orientation on the cooling performance via time-dependent numerical simulations and verify the same with experimental results. We firstly present the experimental study along with the findings. Secondly, we present the numerical models/results, which are compared with the experiments to gain the confidence in the computational methodology. Finally, a sensitivity evaluation has been performed by altering the position and alignment of the jet with respect to the heated surface. Two prime orientations of the jet have been considered, namely, perpendicular and cross jet impingement on the heater. It is found that if jet is placed at an optimum location in either impingement or cross flow position, it can provide similar enhancements.

Environmental and economical impact of LED lighting systems and effect of thermal management

“…We have extensively investigated synthetic jet devices and their unsteady impingement heat transfer. The maximum experimental heat transfer coefficient, based on heater surface area and average heater temperature, ranges from 150 to 240 W/m 2 K [16]. The electrical power consumption of the synthetic jets for a range of driving voltages is given in Figure 13.…”

An investigation into flow and heat transfer of an ultrasonic micro-blower device for electronics cooling applications

“…Early studies with pulsating jets increased convection by a factor of four [3,4], while later piezoelectric devices produced similar performance in a smaller planform [5]. Improved actuator structures led to higher jet speeds, leading to heat transfer enhancement by 10-15 times [2,6,7]. Most synthetic jets have used circular exits, while a recent design by Ghaffari et al [2] applied a slot jet with an aspect ratio of 8:1 and a rectangular cross section.…”

Experimental convective heat transfer in a geometrically large two-dimensional impinging synthetic jet

“…Technologically, the technique is ideally suited for the cooling of electronic components. Several studies have found optimum conditions that maximize the heat transfer [3,5,6,8,9,11,16]. It has generally been found that the intermediate-flow regime, present at moderate jet-to-surface distances, is the most advantageous.…”