Experimental investigation on the effect of wire mesh at the nozzle exit on heat transfer from impinging square jets

Abstract

This paper reports the results of an investigation carried out to study the effect of a wire screen mesh installed at the nozzle exit on the heat transfer performance of a square jet. Towards this, experiments are carried out to cool an electrically heated flat plate with an impinging air jet issued from a square orifice. Three wire meshes with area based porosity values of 0.35, 0.41 and 0.66 respectively are employed in this study. Heat transfer characteristics are presented as stagnation point and local Nusselt numbers. The heat transfer characteristics of the jets with and without the wire meshes are compared at (i) the same mass flow rate of the jet fluid and (ii) the same power consumption of the jet across the nozzle. To support the heat transfer results, mean velocity and turbulence intensities are measured along the jet centerline with a hot-wire anemometer. The effect of dimensionless jet-to-plate distance (2–8.5) on the heat transfer rate is studied as well.