Faculty Publications
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Publications by NITK Faculty
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Item High temperature erosion performance of NiCrAlY/Cr2O3/YSZ plasma spray coatings(Taylor and Francis Ltd., 2023) Reddy, G.M.S.; Prasad, C.D.; Patil, P.; Shetty, G.; Naresh, N.; Ramesh, M.R.The current investigation's objective was to assess the air jet erosion tester's ability to measure the erosive behaviour of plasma sprayed coatings on titanium-15 alloy. 65% NiCrAlY, 30% Cr2O3, and 5% YSZ make up the coating's chemical composition. A study of microstructure and phases was carried out. Microhardness and adhesive strength have both been measured in this work. With impact angles of 30° and 90° at 300°C, 500°C, and 700°C, Al2O3 erodent was utilised in a solid particle erosion test. An optical profilometer was used to calculate the erosion volume loss. The coating erosion resistance was found to be higher than the substrate sample for the test temperature that was employed, and this was more obvious at higher impact angles and higher temperatures The ductile character of the coating is seen in the contour of the deteriorated coating surface. © 2023 Institute of Materials Finishing Published by Taylor & Francis on behalf of the Institute.Item Numerical Investigation of Gasper Air Jet Dynamics in an Aircraft Cabin(Taylor and Francis Ltd., 2023) Srinivasa, V.K.; Kattimani, S.; Reddy C, G.Computational fluid dynamics (CFD) is used to analyze the jet interaction of side-vent and gaspers and their influence on cough jets in aircraft cabins. A control device is designed and proposed to be attached to the existing gasper outlet to widen narrow, high-velocity air jet into a widespread air curtain. It forms a shield around the passenger's face, controlling cough droplets from infected passengers entering the co-passengers breathing zone and pushing the high-velocity cough jet toward the floor. A detailed study on flow distribution with existing gaspers and the newly designed control device is presented. The influence and efficacy of the control device in achieving desired flow spread, droplet spread, and intrusion control into co-passengers breathing zones are evaluated. The simulation showed significant droplets were reaching window and aisle passenger breathing zones in the existing gasper, whereas no droplet was found when the control device was introduced. © 2024 Informa UK Limited, trading as Taylor & Francis Group.Item A CFD-Based Design of S-Shaped Nozzle Attachment for Aircraft Cabin Gaspers(Taylor and Francis Ltd., 2023) Srinivasa, V.K.; Kattimani, S.; Ganga Reddy, C.; Kavya, S.Cough has been the primary mode for transmitting airborne respiratory diseases as the droplets expelled are suspended in the air longer in closed environments like aircraft cabins. Air jets from personal gasper nozzles are studied using computational fluid dynamics (CFD) simulations to understand the flow pattern, which is of high velocity, very narrow, and susceptible to enhanced air mixing. An S-shaped nozzle attachment uses higher-order Bezier curves to spread the flow across the passenger’s face to form a shield to protect the breathing zone from foreign particles. The design of experiments theory, the Box–Behnken design, was employed to understand the influence of nozzle profile geometric parameters on the output criteria through CFD simulations. The numerical simulations were performed on the final design, which shows that the newly designed nozzle attachment can distribute the narrow jet from existing personal gasper nozzles into a curved air curtain across the passenger’s face. © 2024 Informa UK Limited, trading as Taylor & Francis Group.Item Investigation of the effect of NiCrAlY/Cr2O3/YSZ plasma coatings on erosion performance of MDN 420 steel at high temperature(Inderscience Publishers, 2023) Reddy, G.M.S.; Prasad, C.D.; Patil, P.; Shetty, G.K.; Kakur, N.; Ramesh, M.R.The purpose of the current study was to use an air jet erosion tester to examine the erosive behaviour of plasma sprayed coatings on MDN-420 that were composed of 70% NiCrAlY, 25% Cr2O3, and 5% YSZ. Microstructure and phase studies were performed. Measurements were made on the microhardness and adhesion strength. Al2O3 erodent was used in a solid particle erosion test with impact angles of 30° and 90° at 300°C, 500°C, and 700°C. The erosion volume loss was measured using an optical profilometer. For the test temperature used, it was found that the coating’s erosion resistance was greater than that of the substrate and that it was more pronounced at higher impact angles and higher temperatures. The shape of the degraded coating surface reflects the coating’s ductile nature. © © 2023 Inderscience Enterprises Ltd.Item 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