STUDY OF MIXED CONVECTION IN A CYLINDRICA L DUCT - ANALYTICAL NUMERICAL APPROACHES AND EXPERIMENTAL-DETERMINATION OF WALL TEMPERATURE BY INFRARED THERMOGRAPHY

Laminar flow in a horizontal heated duct is characterized by a tempera ture gradient between the top and the bottom of a cross section due to mixed convection phenomenon. Wall temperature field is measured by in frared thermography. The aim of this paper is to present experimental results and analytical study allowing us to put in a prominent positio n some parameters which take into account the mixed convection phenome non and, thereby, to describe the thermal behaviour of the duct. The n umerical approach, using the Navier-Stokes equations coupled to the en ergy equation, completes this study showing, therefore, the secondary flow and the fluid temperature field in a cross section.