Journal of Fluid Science and Technology (May 2009)
Control of Flow and Heat Transfer Characteristics in an Impinging Jet with Acoustic Excitation
Abstract
The experimental study of flow field and heat transfer characteristics of a submerged, rectangular jet impinging normally on a flat plate is presented. Four nozzle-to-surface spacing of H/w=3, 6, 10 and 20 with acoustic excitations was performed experimentally. The forcing Strouhal number is set from St=0.1 to 0.9 at 0.1 intervals. Velocity distributions with two excitation modes, symmetric and asymmetric excitation, are investigated by means of hot-wire measurement. It was found that the basic flow fields changed drastically, while there is little difference of heat transfer characteristic for both the excitation modes. For the short nozzle-to-plate distances, the heat transfer was enhanced in the wall jet region for the excitation of St=0.2. The maximum heat transfer ratio was obtained at the stagnation point for the middle spacing of H/w=6 for St=0.5. It was revealed that the non-periodic velocity component played the most important role in promotion of the heat transfer with acoustic excited impinging jet.
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