Flow control with electrode bank arrangements by electrohydrodynamics force for heat transfer enhancement in a porous medium

摘要

Active flow control with electrohydrodynamics (EHD) force in the channel flow has been numerically investigated for enhancing heat transfer. This study focuses on the effect of electrode bank arrangements and the number of electrodes on corona wind and fluid flow for heat transfer onto a porous medium. Aligned and staggered configurations of electrode banks are compared. The numerical results show that electric field intensity depends on electrical voltage and the number of electrodes. Shear flow is increased with larger numbers of electrodes and in the aligned configuration, resulting in the enhancement of vortex strength. The swirling flow from staggered configurations spread wider than that of aligned configurations, but the aligned configuration produced more turbulence. In addition, the temperature distribution in the channel flow is increased with increasing numbers of electrodes. With the effect of swirling flow, airflow above the porous sample surface is faster leads the heat to more transfer to the porous sample surface. This causes the temperature of porous medium to increase rapidly so the convective heat transfer coefficient on porous medium surface is increased. Finally, the modified case of the numerical results is validated against the experimental results. The experimental flow visualization is based on the incense smoke technique, in order to verify the accuracy of the swirling flow pattern subjected to the electric field. It is shown that the comparison results in both techniques are in good agreement.