APPLICATION OF INFRARED THERMOGRAPHY TO THE EVALUATION OF LOCAL CONVECTIVE HEAT-TRANSFER ON ARRAYS OF CUBICAL PROTRUSIONS

This paper reports on the experimental technique and measurement metho d used for the investigation of the local convective heat transfer fro m cubical protrusions placed on a vertical wall of a rectangular-secti oned wind tunnel. This experimental configuration simulates a simplifi ed air-cooled vertical electronic circuit board, resembling a situatio n in an electronic cabinet. A controlled heat flux was generated by in ternal heating of the elements. An advanced infrared system was used t o measure the surface temperatures of the cubical elements, which is c rucial for determining the local convective heat transfer. The difficu lties and uncertainties encountered in the course of measurements are discussed together with possible solutions of the problems. A selectio n of results, validated by means of an uncertainty analysis, is presen ted, showing a strong variation of the local convective heat transfer around the individual elements. Qualitative interpretation of the loca l heat transfer coefficients was facilitated by smoke visualization of the mean flow pattern around the protrusions. (C) 1997 by Elsevier Sc ience Inc.