Measurements of the convection heat transfer coefficient for a planar walljet: uniform temperature and uniform heat flux boundary conditions

The local heat transfer coefficients for isothermal and uniform heat flux b oundary conditions for a planar wall jet have been determined experimentall y. Hot-wire anemometry surveys were used to quantify the velocity field in the wall jet. A micro-thermocouple was used to quantify the temperature fie ld in the wall jet for the isothermal boundary condition. Infrared (IR) ima ging was applied to measure the wall temperature for the uniform heat flux boundary condition. The difference in the local convection coefficients due to the different thermal boundary conditions was largest at the leading ed ge of the heated wall, becoming insignificant for non-dimensional streamwis e locations exceeding approximately four slot widths away from the exit pla ne of the jet. The present results are for non-dimensional streamwise locat ions that are relevant to automotive windshield defogging/defrosting, which serves as the technological motivation for this study. Specifically, these results are for small non-dimensional streamwise locations compared to tho se in the published literature. (C) 2000 Elsevier Science Inc. All rights r eserved.