Heat transfer with fully developed slot jets impinging on confined concave and convex surfaces

This research investigates the laminar heat transfer characteristics of a milli-scale confined slot jet impinging upon concave and convex surfaces at a uniform heat flux. The flow at the nozzle exit has a fully-developed velocity profile. The effects of Reynolds number (Re), nozzle-to-surface distance (H/B) and the geometrical shape of target surface on local heat transfer are investigated. The heat transfer measurements are conducted at Reynolds numbers ranging from of 200 to 600 and H/B from 2 to 12. The results show that the local Nusselt numbers for both surfaces increase with increasing Reynolds number. The axial distributions of local Nusselt numbers exhibit the peak at the stagnation point and monotonically decrease in the wall jet region, showing a bell-shaped for all Re's and H/B's tested. The results also show that the peak stagnation point Nusselt numbers occur at around H/B = 5-7 for the convex surface. On the contrary, the stagnation point Nusselt numbers for the concave surface tend to gradually decrease as the nozzle-to-surface distance increases. The stagnation point Nusselt numbers for the concave surface are higher than those for the convex surface at all Re's and H/B's tested.