COOLING ENHANCEMENT THROUGH DC IONIC WIND UNDER NATURAL CONVECTION SENSITIVITY TO ELECTRODE SPACING AND ORIENTATION

Ionic wind is an effective technique to enhance natural convection cooling, as it can generate flow with minimum moving parts and power consumption. This paper presents an experimental investigation of ionic wind for heat transfer enhancement for an aluminium heat sink under natural convection. Experiments were performed at different orientations of the aluminium heat sink to determine the relative impact of buoyancy and EHD driven heat transfer. Tests were conducted for different electrode spacing ranging between 5 mm to 15 mm subjected to 5.64 kV corona voltage and considering three different sets of emitters having varied number of electrodes. Vertical orientation of fin yielded maximum advantage in cooling from ionic wind. The enhancement was significantly affected by the number of electrodes in the emitter and electrode spacing. There exists an optimum electrode number and spacing where the enhancement was found to be maximum. For the present study, it was found to be 10 nos. and 10-mm respectively. The results showed that ionic wind can help reduce the thermal resistance by a factor of up to 2.34 compared to natural convection for vertical arrangement. In case of inclined orientation, results suggested existence of an optimal angle for maximum cooling in presence of ionic wind, where the reduction in thermal resistance was up to a factor of 1.6. The increase in corona voltage from 5.64 kV to 7.05 kV, for optimum spacing, caused the enhancement to increase from 2.34 to 3.09 for 10 number of needle electrodes.