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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

TURBULENT HEAT TRANSFER CHARACTERISTICS IN A STAGNATION REGION OF AXI-SYMMETRIC JET IMPINGEMENT

Get access (open in a dialog) DOI: 10.1615/IHTC11.2220
pages 433-438

Sinopsis

The local heat transfer characteristics in a stagnation region were experimentally investigated for an axi-symmetric submerged jet impinging on normal to a heated flat plate. The temperature distribution on the heated flat surface was measured by a thermochromic liquid crystal technique. The stagnation point Nusselt number was correlated for the Reynolds numbers and the nozzle-to-plate spacings as Nuo ∝ Re0572(L/D)−0.00785. For small nozzle-to-plate spacing of L/D=2, the stagnation Nusselt number was proportional to Re052 and the local heat transfer rates showed two peaks. The first and secondary peaks were attributed to the accelerated radial flow at the edge location of nozzle and the transition from a laminar to a turbulent boundary layer, respectively and the ratio (Nu1st/Nu2nd) was found to decrease with increasing Reynolds numbers. For larger nozzle-to-plate spacings (L/D>6), the local heat transfer decreased monotonically with radial distance. The Reynolds number dependence was gradually enhanced with L/D, which resulted from increase of the centerline turbulent intensity of the approaching jet due to strong momentum exchange with the ambient fluids.