Faculty Publications
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Item Heat transfer distribution of impinging flame and air jets - A comparative study(Elsevier Ltd, 2016) Kadam, A.R.; Tajik, A.R.; Hindasageri, V.Heat transfer distribution of impinging flame jet is compared with that of the impinging air jet based on the experimental data reported in literature for methane-air flame jet and air jet impingement for Reynolds number, R=600-1400 and the non-dimensional nozzle tip to impingement plate distance, Z/d=2-6. The comparative data based on mapping experimental data reported in literature suggest that there is a good agreement between the Nusselt numbers for higher Z/d near stagnation region. However, away from the stagnation region, the Nusselt number for flame jet is higher than that of air jet for similar operating conditions of Re and Z/d. A CFD simulation for impinging air jet and impinging flame jet is carried out to explain the physics and reason for the deviations observed in experimental data. A scale analysis is carried out to identify the dominant forces and their influence on the heat transfer distribution on the impingement plate. © 2015 Elsevier Ltd. All rights reserved.Item Experimental study of convective heat transfer distribution of non-interacting wall and perpendicular air jet impingement cooling on flat surface(Elsevier Ltd, 2024) Kumar, C.; Ademane, V.; Madav, V.An experimental study evaluated heat transfer with perpendicular and wall-impinging air jets on stainless steel foil, for Reynolds numbers Re = 3000, 5000, 8000, and 10000, where the perpendicular jet targets the bottom and the wall jet the top, creating a unique, non-interacting effect. Distances to nozzle diameter ratios for wall jets (S/d = 4, 6, 8, 10) and perpendicular jets (Z/d = 2, 4, 6, 8) were varied. Significant heat transfer increases were noted, with the Nusselt number rising by up to 49.20 % for a Z/d = 6 and S/d = 8 combination at Re = 5000. Improvements ranged from 10.03 % to 49.20 %, peaking when the jets' high heat transfer regions overlapped. Optimal performance for Re = 3000 was at S/d = 10, aligning the wall jet's maximum with the perpendicular jet's stagnation area. For Re = 5000 to 10000, optimal S/d values were 8 and 4 for Z/d = 6, 8 and Z/d = 2, 4, respectively. The Nusselt number increase ranged from 29.21 % to 46.57 % at S/d = 10 for Re = 3000, the highest among all tested values. Wall jet heat transfer downstream increased by 90–105 % over perpendicular jets in corresponding regions. Increasing the wall to perpendicular jet distance improved heat transfer near the stagnation point, suggesting this cooling method for high-density electronics like CPUs and GPUs. © 2024 The AuthorsItem Analysis of heat transfer characteristics of a coaxial air jet on a hot surface: An experimental study with circular nozzles of different arrangements(Elsevier B.V., 2025) Kumar, C.; Madav, V.Coaxial jets are widely utilized in various engineering applications where highly localized heat transfer is the requirement, including combustion systems, cooling technologies, propulsion systems, material processing, and environmental control. This study investigates the effects of air jet impinging on a hot surface by varying the nozzle-to-plate distance-to-diameter ratio (Z/d) at values of 2, 4, 6, and 8, along with adjustments in the inner-to-outer jet exit distance ratio (H/d), set at -1, 0, and +1, under different Reynolds numbers (Re) of 5000, 10000, 15000, and 20000. The study provides a comparative analysis of Nusselt number achieved by coaxial jet configurations against conventional circular single-jet impingement, highlighting significant improvements in heat transfer rate The findings demonstrate that coaxial jets markedly enhance heat transfer, particularly at the stagnation point of the foil surface, with the H/d = +1 configuration yielding the best result. An improvement of 191 % is observed for Z/d = 6 and H/d = +1 case when Re is increased from 5000 to 20000, Proving the impact of increase in Re on stagnation Nusselt Number. When stagnation Nusselt number is compared for normal circular jet with that of H/d = +1 case in coaxial jet, a maximum of 88.73 % improvement is seen. This study is important because the results offer valuable insights for optimizing air jet impingement techniques to improve thermal management across a range of industrial applications ranging from Gas turbines to manufacturing industries where localized cooling is the major requirement. The correlations to calculate the stagnation Nusselt number for three configurations of the coaxial jet are developed. © 2025