Impinging jets are used extensively in many heat and mass transfer applications found in industrial processes such as electronic component cooling, aircraft de-icing and turbine blade cooling. Impinging jets exhibit complex flow physics that is difficult to numerically simulate. The flow field characteristics of an impinging jet are coupled to heat and mass transfer that depend on a large number of parameters such as (i) the jet Reynolds number, Re = UjD/ν, where Uj is the jet exit velocity, D the nozzle diameter and ν the fluid kinematic viscosity; (ii) the nozzle to plate distance, H/D; (iii) the jet exit velocity profile and turbulence level; (iv) the jet configuration (such as confined or not) and shape of the nozzle. Typically, four regions can be distinguished in an impinging jet issued from a converging nozzle, (i) the potential core region, (ii) the free jet region, (iii) the impingement or stagnation region, and (iv) the radial wall jet region.
In the present experiments, a round pulsating jet with uniform jet exit velocity was studied at small H/D (= 2.0) while limiting the effect of entrainment by partial confinement. Our results indicated local and overall heat transfer enhancement at Re = 4,606 and 8,024 while a slight reduction was observed for Re = 13,513. The heat transfer measurements were accompanied by detailed planar particle image velocimetry (PIV) measurements.
Link to Publication in Advances in Engineering
Students working on this project: Moti Raizner (PhD)
Research assistant: Vlad Rinsky