An Experimental Study of Mixed, Forced, and Free Convection Heat Transfer From a Horizontal Flat Plate to Air

A heated flat plate is tested in a wind tunnel to study mixed convection in both upward and downward positions. It is found that the local heat transfer coefficient is strongly dependent on the free stream velocity and the temperature difference between the surface and the free stream. The buoyancy effect is more pronounced for the heated plate facing upward. This paper correlates the experimental data in terms of Nusselt, Grashof, and Reynolds numbers. The points of onset of instability caused by the buoyancy effect are also examined and correlated in terms of the dimensionless groups. Experimental data are compared with analysis documented in the literature, and the agreement is found satisfactory.