An impingement heating system was developed for a drying application. A pressurized plenum above the surface to be heated was used. Holes in the bottom of the plenum formed jets that would impinge on the target surface. After impingement, the flow would travel laterally to exit the device. The initial design (Fig. 5) used a large number of relatively small holes, ostensibly to improve uniformity of heat transfer at the surface. Simulation of the flow and heat transfer, as shown in Fig. 5, indicates that the lateral flow of the exiting gases was strong enough to deflect the jets and reduce their effectiveness. Note that in this figure and in Figures 6-8, the simulation domain was limited to a single row of jets. The lateral velocity increases as the exit is approached, and so the jet deflection is strongest near the exit.
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