Abstract:
Characteristics of heat transfer for synthetic jets of air issuing from sharp edged rectangular slots (width ) impinging on a circular cylinder (diameter ), located at a range of spacing from the jet exit, were studied experimentally for a range of Reynolds number. Concurrently, the flow field of these synthetic jets were studied using hot wire anemometry. The results reveal that over most of the parameter range studied, the mean Nusselt number is maximum for smaller orifice exit to cylinder surface spacing. This corresponds directly to presence of higher fluctuations near the orifice exit as established from flow field measurements. It was also found that there exists an optimum cylinder curvature (i.e. cylinder diameter to slot width ratio ( = 1.9) at which synthetic jet impingement heat transfer is maximised. This investigation sheds some light on the heat transfer enhancement potential of synthetic jets from a circular cylinder. From a practical standpoint, these results indicate that synthetic jets can be used for impingement cooling of circular bodies, where free convection is not sufficient, while at the same time, using a continuous jet is not feasible. Such conditions can be anticipated in thermal management of modern electronics, where components are now dissipating more and more power within compact environments requiring alternative solutions. The synthetic jet can offer several advantages in such applications.