Turbulent flow and heat transfer measurements on a curved surface with a fully developed round impinging jet

The effects of the convex surface curvature on the local heat transfer from an axisymmetric impinging jet were investigated. The flow at the nozzle exit has a fully developed velocity profile. The jet Reynolds number (Re) ranges from 11,000 to 50,000, the dimensionless nozzle-to-surface distance (L/d) from 2 to 10, and the dimensionless surface curvature (d/D) from 0.034 to 0.089. The results show that the stagnation point Nusselt number (Nu(st)) increases with increasing value of d/D. The maximum Nusselt number at the stagnation point occurs at L/d congruent to 6 to 8 for all Res and d/Ds tested. Both the stagnation point and the average Nusselt number over the curved surface are well correlated with Re, L/d, and d/D. For larger L/d, Nu(st) dependency on Re is stronger because of an increase of turbulence in the approaching jet as a result of the more active exchange of momentum with a surrounding air. The local Nusselt number decreases monotonically from its maximum value at the stagnation point. However, for L/d = 2 and Re = 23,000, and for L/d less than or equal to 4 and Re = 50,000, the streamwise Nusselt number distributions exhibit secondary maxima at r/d congruent to 2.2. (C) 1997 by Elsevier Science Inc.