Experimental study of free and mixed convective flow of air in a heated cavity

Free and mixed convection in a strongly-heated rectangular open cavity have been investigated experimentally, to observe the effects of cavity shape and inclination, and of ambient wind, on the velocity and temperature distribution were observed. The long edges of the cavity were horizontal, and parallel to an axis around which the cavity could be rotated. The aperture plane was either vertical (ALPHA = 0), or inclined downward at (ALPHA = 20 deg or ALPHA = 45 deg). The height of the aperture, b, was always 0.0947 m, while the depth of the cavity, a, was set so that a/b = 0.5, 1.0, or 1.46. The bottom and back walls were electrically heated - the top wall was indirectly heated by conduction, radiation and convection. The average wall temperature and the ambient temperature were used to define the dimensionless overheat and Grashof numbers. The Prandtl number was that of air. In the studies of mixed convection, the axis of rotation was horizontal and normal to the ambient wind. The Reynolds number was varied from Re = 120 - 1100 to Re = 2000 = 8740. For both free and mixed convection, wall and gas temperature were measured with thermocouples, and shadowgraph pictures were taken.