An experimental study on heat transfer of pulsating air flow in metal foam subjected to constant heat flux

In this study, the effect of pulsating air flow on heat transfer was investigated experimentally, while constant heat flux was applied with an electric heater to the side surface of the cylindrical duct with metal foam inside. Reynolds numbers in the range of 5932–8592 were studied at three different fan speeds. Pulsating flow experiments were carried out in the range of 12.0–27.9 Womersley numbers. It has been observed that the surface and air temperatures are not affected by the flow frequencies in this range and are independent of time. With the data obtained, Nusselt number values were calculated for the fully developed region, and the Nusselt number ratio was defined in order to compare the steady flow with the pulsating flow. Nusselt correlation was established for the fully developed region depending on the Reynolds number and the Womersley number in the studied range. It has been determined that the effect of frequency on the heat transfer in the case of pulsating flow is weak, but the heat transfer tends to decrease as the frequency increases.