Thermal characteristics of metal foamed flat plate with circular and elliptical impinging jets

Abstract

ABSTRACT Here, the thermal characteristics of open-cell metal foam (OCMF) integrated stainless steel (SS) foil are investigated experimentally during air jet impingement using circular and elliptical nozzles. The aspect ratio (AR) of the elliptical nozzle is varied from 2 to 4, the Reynolds number (Re) is varied within 5000 - 25,000 and the impinging distance (z/d) is varied within 3–7 during tests. Thin foil thermal imaging infrared thermography has been utilized to record the temperature, and the measured temperature data is used to estimate the performance parameters. The thermal performance is evaluated based on the local, average, and stagnation Nusselt number (Nu) for different configurations. The integration of OCMF with SS foil has been found to significantly enhance heat transfer at the stagnation point in different nozzle configurations. At a Reynolds number (Re) of 5000, the percentage increase in stagnation Nu with foam compared to when there is no foam is found to be 80%, 46%, 38%, and 24% for nozzles with AR of 1, 2, 3, and 4, respectively. The local (0 ≤ x/d ≤2) and average values of Nu for lower impinging distance (z/d ≤5) are found to be higher for the elliptical nozzles, while for z/d ˃ 5, the circular nozzle is found to exhibit better performance. The peak average Nu with nozzle AR = 4 at Re = 25000 is found to be higher than nozzle AR of 3, 2, and 1 by 6.75%, 8.72%, and 23.44%, respectively. Additionally, for the same Re, the peak average Nu of nozzles with AR = 4, AR = 3, and AR = 2 is higher than the circular nozzle by 23.44%, 15.62%, and 13.54%, respectively. New correlations based on experimental results are proposed to determine the local and average Nusselt number as a function of various operating parameters.