Influence of Surface Heating Condition on Local Heat Transfer in Enclosed Corotating Disks With Axial Throughflow

Local heat transfer in a rotating cavity with axial throughflow was experimentally investigated. The rotating cavity was bounded by two plane disks and a cylindrical rim (shroud). The ratio of the rim span to the disk outer radius was 0.4 and the ratio of the disk inner radius to outer radius was 0.25. This study investigated the effects of axial coolant flow rate, rotation speed, and disk surface heating condition on the local heat transfer coefficient distributions inside the cavity. Three cavity surface heating conditions were tested: case 1 - upstream and downstream disks with radially increasing temperature but colder than rim; case 2 - upstream and downstream disks at uniform temperature but colder than rim; and case 3 - upstream and downstream disks and rim at uniform temperature. Tests were systematically performed for the axial flow Reynolds numbers between 2500 and 25,000, the rotational Reynolds numbers between 0 and 5.11 × 10⁵, and the rotational Grashof numbers between 5 × 10⁶ and 1.3 × 10¹⁰, respectively. The results show that the local heat transfer coefficients for the non-rotating cavity increase with increasing axial flow Reynolds number. However, the local heat transfer coefficients initially decrease and then increase with increasing rotational Reynolds number. In general, the heat transfer coefficients on the rim for case 2 surface heating condition are higher than those for case 1 and case 3 whereas the heat transfer coefficients on the upstream and downstream disks for case 3 surface heating condition are higher than those for case 1 and case 2.