Application of a schlieren technique to heat transfer measurements in free-convection

Abstract

The application of a quantitative schlieren technique to the study of two-dimensional free convection heat transfer is presented. As it is well known, the schlieren technique utilizes the refraction of light rays to display a pattern related to the temperature field. The schlieren system employed here makes use of an opaque filament to identify regions of fluid that deflect light rays by the same amount. The schlieren images recorded enable the temperature field and local heat transfer coefficients to be reconstructed. After a description of the experimental technique, results concerning standard geometrical configurations (a single, vertical plate and parallel vertical channels) are presented and compared with theoretical predictions and numerical computations.