Heat transfer under a pulsed slot turbulent impinging jet at large temperature differences

Abstract

Pulsed impinging jets have received increasing interest for their potential in heat and mass transfer enhancement. However, published results on effects of pulsations under different flow and geometrical parameters have shown conflicting results. To further understand the flow and thermal processes in pulsed impinging jets, a numerical investigation has been performed on a two dimensional pulsed turbulent impinging jet under large temperature differences between the jet flow and the impinging surface to examine the effect of temperature-dependent thermophysical properties along with pulsation of the jet on the local Nusselt number distribution on the target surface. The numerical results show that the local time-averaged Nusselt numbers calculated with various thermal property values at the jet, film and impingement surface temperatures differ significantly for large temperature difference cases (>100 K). A parametric study for both heating and cooling cases indicates that no obvious enhancement by single sinusoidal pulsation can be found under current conditions except for cases with large temperature differences at distances far from stagnation point, i.e. in the wall jet region.