Flat Surface Heat Transfer Enhancement By An Impinging Circular Free Water Jet

Abstract

Impinging a free water jet onto a heated flat plate was investigated with and without mesh screens. Increasing the jet velocity increased the surface cooling rate via turbulence increase. Lower temperature gradients existed due to the faster wetting front propagation for the water film to advance in shorter times. Decreasing the nozzle-to-block spacing slightly increased the cooling rates by counteracting effects of gravity acceleration and jet momentum dispersion. The turbulence role in the heat transfer enhancement was optimized via opposite changes in the strain rate and largest turbulence scale. Displacing the screens from the impingement zone increased the heat flux.

Keywords:

• boiling
• conduction
• convection