Heat/Mass Transfer in Rotating, Smooth, High Aspect-Ratio (4:1) Coolant Channels With Curved Walls in 90° and 45° Orientation

The paper presents an experimental study of heat/mass transfer coefficient in 4:1 aspect ratio smooth channels with non-uniform cross-sections. Curved leading and trailing walls are studied for two curvatures and for two different curvature configurations. One configuration has curved walls with curvature corresponding to the blade profile (positive curvature on both leading and trailing walls), and the other configuration has leading and trailing walls that curve inwards into the coolant passage (negative curvature on the leading surface and positive curvature on the trailing surface). The experiments are conducted in a rotating two-pass coolant channel facility using the naphthalene sublimation technique. Only the radially outward flow is considered for the present study at a Reynolds number of 20,000, rotation numbers in the range 0–0.051 and for 90° and 45° orientations with respect to the direction of rotation. In addition to area averaged values, the span-wise mass transfer distributions of fully developed regions of the channel walls are presented in order to delineate the effects of rotation number, channel shape and orientation. The mass transfer data from the curved wall channels are compared to those from a smooth 4:1 rectangular duct with similar flow parameters. Pressure drop along each channel is also measured and put in perspective of the mass/heat transfer results for the 90° orientation, through the presentation of a performance factor.