Caracterização fluidodinâmica e térmica de jatos sintéticos

Abstract

Current electronic components are becoming ever more potent and densly integrated, which requires further increases in the efficiency of heat dissipation. With current fan-based heat dissipation techniques with air as the working fluid becoming outdated, there is a pressing need to develop more eficient methods to cope with demand. So far, three techniques have been the primary focus of studies in this area: liquid cooling, microchannel heat exchangers and synthetic jets used to promote increased momentum transfer. Analysis of such devices at the small physical scale of electronic components is somewhat problematic in experimental form so that a computational fluid dynamics (CFD) approach is recommended. The main objective of this study is thus to utilize a CFD approach to establish the performance characteristics of a synthetic jet impacting against a heated surface. The flexibility of a numerical approach also allows the examination of the sensibility of the design with respect to several physycal and geometric parameters such as Reynolds number, pulsing frequency, jet orifice shape and size, cavity size and distance between the heated surface and the device. Such results, provide insight in the effect of physical and geometric parameters in the jet formation and heat dissipation. The combined knowledge of this study allowed the development of a practical correlation for the Nusselt number based on the Strouhal number (normalized pulsing frequency), Reynolds number, Prandtl number and the distance between the heated surface and the synthetic jet. This result allows improved predictions of a jet impacting against a heated surface and, consequently, adds an important contribution to other studies in this area. It is expected that the results presented here will be the starting point for further work, in which increasingly complex geometries such as actuators combined with heat exchangers equipped with fins, coolers or microchannels are examined to further improve the knowledge in the field of electronic cooling.