Impinging jet heat transfer on a target plate was enhanced by using two parallel confining
plates mounted between a rectangular nozzle end plate and a jet target plate. The target
plate was set equal to 2, 3, 4, and 5 times the jet exit width, h, and the gap ratio of two parallel confining plates, W/h, were changed from 2.7 to 8.0 only by impinging length H=5h and from 2.7 to 6.7 by H≠5h. Two confining parallel plates mounted near the jet exit produced
swing-type flow under some conditions. As a result, the maximum Nusselt number
attained around the stagnation point was augmented by about 50% compared to the one
for normal impinging jet without the two parallel plates and then spatial mean Nusselt
number was increased by about 40%.