ISSN Online: 2377-424X
International Heat Transfer Conference 4
COMBINED FREE AND FORCED CONVECTION FROM HORIZONTAL SLOWLY ROTATING DISCS
Abstract
This paper investigates the flow field obtained over an upwards facing heated horizontal disc slowly rotating in air, A new similarity solution for this case of combined free and forced convection is found when the disc surface temperature varies with the second power of the radius of rotation. The influence of the forced flow upon the free convective motion is found to depend upon the parameter R2.5/G.
The zone of stable inward laminar flow over the disc breaks down at a location which cannot be calculated from laminar boundary later theory. This information has therefore to be obtained from tests in order for the complete flow field over the disc to be known. A series of tests were performed which seem to indicate that laminar breakdown occurs at a location which approaches asymptotically Gx1/3=100 as the Grashof number based upon the distance from the edge Gx is raised. For a slowly rotating disc the plot Gx1/5 versus R1/2 tends towards a straight line.
The zone of stable inward laminar flow over the disc breaks down at a location which cannot be calculated from laminar boundary later theory. This information has therefore to be obtained from tests in order for the complete flow field over the disc to be known. A series of tests were performed which seem to indicate that laminar breakdown occurs at a location which approaches asymptotically Gx1/3=100 as the Grashof number based upon the distance from the edge Gx is raised. For a slowly rotating disc the plot Gx1/5 versus R1/2 tends towards a straight line.