Local heat transfer in an enclosed corotating disk with axial throughflow
Abstract
Local heat transfer in an enclosed corotating disk with axial throughflow was investigated. The rotating cavity has two plane disks and a cylindrical rim (shroud). The ratio of the rim span to the disk outer radius is 0.4 and the ratio of the disk inner radius to outer radius is 0.25. The objectives of this study are to investigate the effects of axial coolant flow rate, rotational speed, and disk surface temperature on the local heat transfer coefficient distributions inside the disk cavity. Six disk surface heating conditions (BC1, BC2, BC3, BC4, BC5, and BC6) were tested for the axial flow Reynolds numbers between 2500 and 25,000, the rotational Reynolds numbers between 0 and 5.11 x 10(exp 5), and the rotational Grashof numbers between 1.8 x 10(exp 6) and 2.2 x 10(exp 10), respectively. The results showed that the disk cavity local heat transfer coefficients for the nonrotating cavity increase with increasing axial flow Reynolds number. However, the cavity local heat transfer coefficients decrease with increasing rotational Reynolds number and then increase with further increasing rotational Reynolds number. The downstream disk and rim generally have higher Nusselt numbers than the upstream disk. The Nusselt numbers on the upstream disk for BC 4, BC 5, and BC 6 are respectively lower than BC 1 and the Nusselt numbers on the downstream disk for BC 3, BC 5, and BC 6 are respectively lower than BC 1. However, the uneven disk temperature effect on the local Nusselt numbers decrease with decreasing axial Reynolds number and decrease with low rotational Reynolds number (Re(sub r) = 0 to 3.19 x 10(exp 5)) and increase with high rotational Reynolds number (Re(sub r) = 5.11 x 10(exp 5)). The disk cavity Nusselt numbers for BC 1 and BC 2 are comparable. In general, the modified Nusselt numbers (Nu(sub y)) on the upstream and downstream disks of this study are lower than the flat vertical wall natural convection correlations. The Nusselt numbers for Re(sub z) = 25,000 agree well with that of Farthing et al. (Re(sub z) = 2 x 10(exp 4)) except the present data are higher and lower, respectively, near the disk entrance (Gr(sub y) = 10(exp 10)) and near the rim (Gr(sub y) = 10(exp 7)). The averaged Nusselt numbers on the rim increase with increasing rotational Grashof numbers. However, the present rim data are lower than the natural convection correlation from the face down heated plate.
 Publication:

Ph.D. Thesis
 Pub Date:
 1992
 Bibcode:
 1992PhDT........48K
 Keywords:

 Axial Flow;
 Corotation;
 Grashof Number;
 Heat Transfer;
 Heat Transfer Coefficients;
 Nusselt Number;
 Reynolds Number;
 Rotating Disks;
 Angular Velocity;
 Coolants;
 Flow Velocity;
 Shrouds;
 Surface Temperature;
 Temperature Effects;
 Fluid Mechanics and Heat Transfer