The investigation of heat transfer characteristics of pulsating impinging jet on a flat surface

This study is presented convective heat transfer characteristics to a circular heated surface by impinging pulsating jet under turbulent flow conditions. In investigations, the effects of the distance of jet and target surface (H/D), pulsating frequency and pulsating amplitude on heat transfer are analyzed. In the experimental investigations, the dimensionless distance H/D ratio, the pulsating frequency and pulsating amplitude are changed while the geometry and Prandtl number remain constant for all cases, and the effect of these parameters on heat transfer is analyzed. The experiments are performed at six different frequencies and four different amplitudes for three different H/D ratios. The problem is also investigated numerically by using the Fluent commercial code. In order to explain the heat transfer mechanism, instantaneous velocity and temperature profiles are obtained. The numerical results reveal that there is a disruptive effect on the hydrodynamic boundary layer of pulsating jet, which improves the heat transfer. The obtained results are given as dimensionless parameters. It is observed that, the heat transfer enhancement increases with increasing both Womersley number (Wo) and dimensionless amplitude (Ao) at the high H/D ratio.