Rotation Effect on Jet Impingement Heat Transfer in Smooth Rectangular Channels With Four Heated Walls and Radially Outward Crossflow

Abstract

The effect of channel rotation on jet impingement cooling by arrays of circular jets in two channels was studied. Jet flow direction was in the direction of rotation in one channel and opposite to the rotation direction in the other channel. The jets impinged normally on two smooth target walls. Heat transfer results are presented for these two target walls, for the jet walls containing the jet producing orifices, and for side walls, connecting the target and jet walls. The flow exited the channels in a single direction, radially outward, creating a crossflow on jets at larger radii. The mean test model radius-to-jet diameter ratio was 397. The jet rotation number was varied from 0.0 to 0.0028 and the isolated effects of jet Reynolds number (5000 and 10,000), and wall-to-coolant temperature difference ratio (0.0855 and 0.129) were measured. The results for nonrotating conditions show that the Nusselt numbers for the target and jet walls in both channels are about the same and are greater than those for the side walls of both channels. However, as rotation number increases, the heat transfer coefficients for all walls in both channels decrease up to 20 percent below those results that correspond to nonrotating conditions. As the wall-to-coolant temperature difference ratio increases, heat transfer coefficient decreases up to 10 percent with other parameters held constant.