MIXED CONVECTION HEAT TRANSFER IN AN ANNULUS WITH ROTATING INNER CYLINDER

Natural as well as mixed convection heat transfer are studied in an annulus formed by concentric cylinders where the outer cylinder is the enclosure and the inner cylinder is either stationary or rotating about its axis at various angular speeds. The parameters involved in this study are Rayleigh number (Ra), Richardson number (Ri), Rotational Reynolds number (Re) and Nusselt Number (Nu). The present study uses a two Dimensional steady state Finite Volume method with a coupled scheme approach of pressure-velocity coupling. Three cases of Ra with a temperature difference of 5K, 50K and 90K are investigated. For each case, natural convection and mixed convection heat transfer is studied by varying Ri. For mixed convection study, the range of values used for Ri are 10(-3)-10(3) in multiples of 10 and hence the rotational speed of inner cylinder is varied suitably. For each case of Ra, for each Ri, local Nu variation on the rotating cylinder as well as the enclosure are presented. Surface averaged values of Nu are plotted against Ri for different values of Ra. Further, radial velocity component variation is also examined along a particular region in the domain.