Rotation effect on jet impingement heat transfer in smooth rectangular channels with heated target walls and film coolant extraction
The effect of channel rotation on jet impingement cooling by arrays of circular jets in two channels was studied. These channels rotated orthogonally; that is the axes of these channels are perpendicular to the axis of rotation and also parallel to the radial direction. Impinging jet flows were in the direction of rotation in one channel and opposite to the direction of rotation in the other channel. The jets impinged normally on the smooth, heated target wall in each channel. The spent air exited the channels through extraction holes in each target wall which eliminates cross flow on other jets. The mean test model radius to jet diameter ratio is 397 and the channel length to jet diameter ratio is 151. Jet rotation number was varied from 0.0 to 0.0028 and the isolated effects of jet Reynolds number (5000 to 10000) and heated wall-to-coolant temperature difference ratio (0.0855 and 0.129) were measured. For the target walls with jet flow in the direction of rotation (or opposite to the direction of rotation), as rotation number increases heat transfer decreases up to 25% (or 15%) as compared to corresponding results for non-rotating conditions. This is due to the changes in flow distribution and rotation induced Coriolis and centrifugal forces. Also, as wall-to-coolant temperature difference ratio increases, the heat transfer coefficients remain within 2% under rotating conditions while other parameters are held constant. As jet Reynolds number and rotation speed vary in combination while retaining constant jet rotation number, the effect on Nusselt number ratio is relatively small.
American Society of Mechanical Engineers (Paper)
author list (cited authors)
Parsons, J. A., & Han, J. C.
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