Interaction between the jet and wakes as a method for passive control of plane impinging jets

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.A planar impinging air jet was experimentally investigated, with passive flow control as means of enhancement of impingement heat/mass transfer. The control was achieved by means of an array of small cylinders, fixed at the nozzle lips so as to bridge the nozzle exit gap. Experiments used mainly the naphthalene sublimation technique, with the resultant local mass transfer coefficient converted to prediction of the corresponding heat transfer by means of the heat/mass transfer analogy. Also measured were the local velocities. The experiment revealed the expected spatially periodical character of the flow field and heat/mass transfer distributions. To quantify the heat/mass transfer effects, three procedures are proposed. Compared with the standard planar impinging jet at the optimal nozzle-to-wall distance, the enhancement of the average heat/mass transfer was demonstrated to reach up to 8%.