09. Heat and Mass Transfer

The plasma actuator (PA), a flow control device, can induce ionic wind along the surface on which it is installed. Due to its advantages such as being thin and absent from moving parts, it is expected to enhance heat transfer in applications such as electronic equipment cooling and film cooling by accelerating cooling air. However, it is known that the PA also heats the surrounding gas during operation due to discharge. For applications aimed at enhancing heat transfer, it is necessary to evaluate the cooling effect while considering the impact of gas heating. Therefore, the objective of this study is to establish an experimental method to separately evaluate the heat transfer enhancement effect and the gas heating effect. We conducted forced convection heat transfer experiments with a heated plate in a wind tunnel. The heat transfer enhancement effect and the gas heating effect of the PA were modeled as changes in the Nusselt number and the freestream temperature, respectively. These were calculated by solving heat transfer equations, which account for the effects of the PA, for two different heated plate conditions. Additionally, we defined two dimensionless parameters, J and Q, to characterize the effects of the PA. The dimensionless numbers J and Q are related to the ionic wind momentum and the gas heating energy of the PA, respectively. We plotted the change in the Nusselt number against J and the change in the dimensionless freestream temperature against Q. The results confirmed that the change in the Nusselt number was characterized solely by J, whereas the temperature change was characterized solely by Q. This indicates that it is possible to estimate the surface temperature changes induced by the PA by establishing the relationships between the Nusselt number change and J, and the temperature change and Q in advance.

Prof.

Hiroyuki NISHIDA