Investigation of heat transfer from circular cylinders in high power 10 kHz and 20 kHz acoustic resonant fields

This paper reports on the experimental results of heat transfer in 10 and 20 kHz acoustic resonant standing wave fields for a small cylinder by means of hot-film anemometry. To obtain the high power 10 and 20 kHz acoustic resonant standing wave fields, pairs of oscillating transmitters, each working with slightly different frequencies, were employed. It is shown that the effective sound pressure depends on several parameters like the irradiation number, the amplitude of the transmitters, the impedance, and the frequency. An empirical equation is given to calculate the effective sound pressure in the acoustic standing wave field. A remarkable enhancement of the heat transfer can be observed in the acoustic field compared to free convection. Finally, a correlation is given to predict the heat transfer in such acoustic fields. This correlation is valid for a wide range of Reynolds numbers (4-3 000). (C) 2000 Editions scientifiques et medicales Elsevier SAS.