The effect of jet-to-jet spacing on the local Nusselt number for confined c
ircular air jets vertically impinging on a flat plate is investigated. Five
jets in equilaterally staggered arrays are considered. The surface heat fl
ux on the plate is 1500 W m(-2). The jet diameter is 3 mm. Three different
jet Reynolds numbers (Re = 10,000, 20,000 and 30,000) are individually cons
idered. The influence of jet-to-jet spacing, Re and jet height on the stagn
ation Nusselt number of the center jet is experimentally investigated. An o
ptimum ratio of jet-to-jet spacing to jet diameter, (s/d)(opt,) is obtained
. The existence of the (s/d)(opt) is attributed to jet interference before
impingement and/or formation of jet fountain between two adjacent jets. The
stagnation Nusselt number is correlated as a function of Re, s/d and H/d.
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