Evaluation of thermal field in Buoyancy-induced flows by a Schlieren method

Abstract

Abstract The aim of this work is to perform a quantitative experimental investigation of two-dimensional buoyancy-induced flows using a schlieren method. The schlieren technique uses the refraction of light rays to display a pattern related to the temperature field. The employed schlieren system makes use of an opaque filament to identify regions of fluid deflecting light rays by the same amount. An iterative inverse technique is developed to reconstruct the temperature field from optical data. After a description of the experimental technique and the data processing features, results concerning the temperature profile reconstruction for natural convective flows are presented. Attention is devoted to air buoyancy flows induced by a single heated vertical plate and by an array of four heated vertical plates. Reconstructed temperature data are compared with theoretical predictions and with direct temperature measurements performed by thermocouples.