Time-averaged and reverse transition in oscillatory air convection in a differentially heated rotating cubic cavity

Abstract

An experimental study was carried out to investigate the time-averaged and unsteady thermal characteristics in an inclined cubic air cavity, subject to differential heating across a pair of side walls and subject to rotation about an axis which is normal to the insulated bottom wall and through the geometric center of the cavity. Specifically, the air temperature in the cavity at selected locations was measured for both steady and unsteady flows. Results were obtained for the cavity height H=10 and 15 cm, temperature difference Delta T ranging from 2 to 10 degrees C, rotation rate Omega from 0 to 452.9 rpm and inclined angle phi from 0 to 90 degrees (heated from below). Time records of the air temperature showed the presence of the how re-stabilization in two different ranges of the rotation rates. Thus, the transient oscillatory flow can be stabilized by increasing the cavity rotation when the rotation rate is in these ranges. This flow restabilization is more pronounced for a higher inclined angle. Moreover, a power spectrum density analysis of the time records indicated that at low rotation rates the amplitudes of the temperature oscillation are location dependent, but the oscillation frequencies at various locations for a given set of Delta T, Omega and phi are the same. (C) 1997 Elsevier Science Ltd.