Flow and Forced Convective Heat Transfer of Round Impinging Jet. Control by Coaxial Annular Subjet.

Abstract

Flow and forced convective heat transfer of double coaxial pipe jets, which consist of a central round main air jet and coaxial annular sub-air jet, impinging normally on to a flat plate are examined by experimental and numerical analyses. It was found that the mean flow characteristics, velocity profile, maximun velocity, spread of jet, pressure distribution, and others, and turbulent characteristics of round impinging jet can be controlled by annular coaxial subjet. In particular, turbulent components near the plate are augmented considerably with the use of the annular coaxial sub jet. Depending on this, the heat transfer on the plate is also augmented markedly. Numerical analysis was carried out using the k-eturbulent model, but the analysis on heat transfer did not correspond well to experimental results.