Control of Flow and Heat Transfer Characteristics in an Impinging Jet with Acoustic Excitation

抄録

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.