Convective Heat Transfer in the Stagnation Zone of an Axisymmetric Upward Jet Impinging on a Stationary Flat Surface
Experiments were conducted to measure the local heat transfer coefficient in the stagnation zone of an upward, free oil jets impinging upon a stationary, heated flat surface. Six tube-style nozzles were used having diameters ranging from 0.864 mm to 3.073 mm. The oil viscosity ratio, based upon the nozzle and surface temperatures, varied from 0.472 to 0.903. The fluids tested included Prandtl numbers ranging from 62 to 142, and by varying the flow rate the Reynolds number ranged from 268 to 3,810. Testing demonstrated that the Reynolds number, which includes the nozzle diameter as the characteristic length, did not account properly for the effect of nozzle diameter on the heat transfer rate. Introduction of the Bond number into the Nusselt number correlation did allow a good correlation for all nozzle diameters.