Investigation of the effect on heat transfer of multiplesynthetic jets addition to the cross flow in a channel

In this study, heat transfer from a surface having constant heat flux in a square-section channel by adding multiple impinging synthetic jets (zero mass-flux) to the forced cross flow was investigated experimentally and numerically. In forced channel flow, the effect of six synthetic jets placed crosswise to the main flow on the heat transfer at four different amplitudes and six different frequencies experimentally and numerically investigated. Jets made of copper pipes are vertically immersed in the main flow and placed at a distance of 2 cm from the heated surface (impact surface), and their effects on heat transfer in the turbulent regime of the main flow are analyzed. Temperature measurements were made with thermocouples at different Reynolds numbers at the channel inlets and outlets and on the heated surface. Nusselt numbers, which are an indicator of heat transfer, were calculated based on these measured temperatures. In order to explain the heat transfer mechanism, the problem was also simulated numerically using Computational Fluid Dynamics (CFD). Instantaneous flow images were obtained through numerical solutions based on experimental inputs, and the physical mechanism was tried to be interpreted. In comparisons with the smooth channel, it was observed that the addition of synthetic jet caused significant increases in heat transfer. Along with the increase in heat transfer, pressure losses were calculated and analyzed together, and the results were given in the form of coefficient of performance depending on the dimensionless flow parameters. Although there is slightly increase in pressure loss, it has been observed that there are significant increases in heat transfer. Keywords: Multiple Synthetic Jet, Forced Convection, Channel Flow, Heat Transfer Enhancement.