Heat and mass transfer can be greatly increased when using impinging jets,
regardless the application. The reason behind this is the complex behavior
of the impinging jet flow which is leading to the generation of a multitude
of flow phenomena, like: large-scale structures, small scale turbulent
mixing, large curvature involving strong normal stresses and strong shear,
stagnation, separation and re-attachment of the wall boundary layers,
increased heat transfer at the impinged plate. All these phenomena listed
above have highly unsteady nature and even though a lot of scientific
studies have approached this subject, the impinging jet is not fully
understood due to the difficulties of carrying out detailed experimental and
numerically investigations. Nevertheless, for heat transfer enhancement in
impinging jet applications, both passive and active strategies are employed.
The effect of nozzle geometry and the impinging surface macrostructure
modification are some of the most prominent passive strategies. On the other
side, the most used active strategies utilize acoustical and mechanical
oscillations in the exit plane of the flow, which in certain situations
favors mixing enhancement. This is favored by the intensification of some
instabilities and by the onset of large scale vortices with important levels
of energy.
Heat and Mass Transfer of Impinging Jet Flow with Shower Head Flow on a Heated Disc in a Cylindrical Flow Channel
