Mixed convection heat transfer and flow in vertically heated channels

Experiments are performed to study and understand buoyancy effect on the heat transfer process and flow in a finite vertical, rectangular channel. One of the wall is insulated and the opposite wall is heated uniformly. Uniform air flow is made to enter the channel. Both the case for buoyancy assisted flow and the case for opposed flow are studied. The mean velocity is controlled at values that the channel flow is either laminar or turbulent when the plate is not heated. Both flow visualization and temperature fluctuation measurements are conducted and used to provide informations on flow structure. Flow reversal occurs initially in the downstream and moves periodically upstream as the buoyancy parameter Gr/Re increases, which destabilizes the flow structure and enhances the heat transfer process in the range it traverses. The effect of buoyancy force on the local and averaged Nusselt number over the heated plate is studied. The buoyancy parameter studied ranges from 8 x 10² to 6 x 10⁴.