1 SURFACE HEAT TRANSFER FROM AN IMPINGING SYNTHETIC AIR JET

The implementation of synthetic jets for use in the cooling of electronics is a relatively new technology. Steady flow impinging jets can produce relatively high heat transfer coefficients; however it has been shown by Kercher et al., (2003) that synthetic jets can deliver similar cooling effects without the need for an air supply system. Impinging synthetic jets are therefore an extremely promising alternative for applications such as cooling of electronic components, Glezer et al., (2000). A study has been undertaken of the heat transfer distribution to an impinging synthetic jet flow with two exit geometries; contoured nozzle and orifice plate. The jet is directed at a heated copper plate, which approximates a uniform wall temperature boundary condition. Nusselt number profiles generated by the synthetic jet for various driving frequencies and heights above the plate were obtained. Tests were conducted for a range of experimental parameters, which include driving frequencies from 40 Hz to 160 Hz, non-dimensional surface to jet exit spacings (H/D) from 1 to 6 and nozzle exit geometry. Heat transfer measurements were compared for both a contoured jet nozzle and an orifice nozzle. Jet exit geometry is shown to have a substantial effect on the flow characteristics of the synthetic jet; this results in significantly different heat transfer distributions