ROTATION EFFECT ON JET IMPINGEMENT HEAT-TRANSFER IN SMOOTH RECTANGULAR CHANNELS WITH 4 HEATED WALLS AND RADIALLY OUTWARD CROSS-FLOW

The effect of channel rotation on jet impingement cooling by arrays of circular jets in two channels was studied Jet flow direction was in t he direction of rotation in one channel and opposite to the rotation d irection in the other channel. The jets impinged normally on two smoot h target walls. Heat transfer results are presented for these two targ et walls, for the jet walls containing the jet producing orifices, and for side walls connecting the target and jet walls. The flow exited t he channels in a single direction, radially outward, creating a crossf low on jets at larger radii. The mean test model radius-to-jet diamete r 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), an d wall-to-coolant temperature difference ratio (0.0855 and 0.129) were measured. The results for nonrotating conditions show that the Nussel t 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. H owever, as rotation number increases, the heat transfer coefficients f or all walls in both channels decrease up to 20 percent below those re sults that correspond to nonrotating conditions. As the wall-to-coolan t temperature difference ratio increases, heat transfer coefficient de creases up to 10 percent with other parameters held constant.