| Experimental measurements were conducted to investigate the local convective heat transfer of a free surface, upward axisymmetric liquid jet impinging onto a flat surface. The investigation was divided into two sections: static and dynamic testing. For the static testing, upward free jets produced by six tube-style nozzle diameters (0.864 to 3.073 mm) impinged upon a flat surface containing an electrically heated 3.5 mm by 10 mm, AISI grade 304 stainless steel strip. Fluid Prandtl numbers ranged from 62 to 142, and the Reynolds number varied from 268 to 3810. The resulting surface temperature produced a fluid viscosity ratio, based on jet temperature to surface temperature, ranging from 0.472 to 0.903. Introducing the Bond number (0.179 to 2.407) allowed the stagnation zone Nusselt number data, for all flow rates and jet diameters, to collapse onto a single correlation for 91.5% of the data within 10% error.;Beyond the stagnation zone, data was used to develop a correlation in the radial direction. The correlation was able to account for 78.8% of the data within 10% and 93.6% of the data within 15%. In addition, the Nusselt number is reduced by approximately 30% of the peak at a defined r/d = 2 and reduced up to 80% at r/d = 6. An area averaged Nusselt number correlation was developed that fits 74.2% of the data to within 10%, and 95.0% of the data within 15%.;The dynamic portion involved reciprocating the impingement surface at four rotational speeds: 150, 200, 500 and 1,000 rpm. For the dynamic testing, only one nozzle diameter was used, 1.676 mm, but two Prandtl numbers, 117 and 137 and two viscosity ratio, 0.622 to 0.877, were tested. The Reynolds number cyclically varied and for one cycle ranged from 1,440 to 2,890. The quasi-steady state correlation was able to predict the instantaneous Nusselt number in the stagnation zone within -11.6/ 7.9 % and the root mean square value within 2.2% of the measured Nusselt number in the stagnation zone. |
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