Convective heat transfer characteristics from combined mechanical and supply pulsed radial reattaching jets

The heat transfer characteristics of combined mechanically and supply pulsated radial reattaching jets, CPRJR, were documented as a function of nozzle exit angle (0° and 20°), non-dimensional gap height (0.05 and 0.13), non-dimensional flow guide height (0.8 and 1.16), mechanical pulsation rate (5 and 10 Hz), mechanical to supply pulsation rate (1:1, 1:2, 1:3, and 1:4), phase angle (0° and 180°), and Reynolds number (1683 and 2366). Air was forced through a supply pulsation mechanism and then through a pulsated nozzle diverter apparatus. The air impinged on a heated plate where instantaneous heat flux and surface temperature measurements were collected and analyzed on instantaneous, ensemble-averaged, and area-averaged bases. heat transfer can be characterized as a frequency interference of mechanical and supply pulsation effects. Significant improvement, up to 72%, over the corresponding mechanical pulsation case was found to occur for a supply-to-mechanical ratio of 3:1 with a phase angle of 0°. In general, the increased heat transfer rates were associated with the an increase in surface-directed momentum caused by increased cycle “on” mass flow rate and corresponding entrainment.