Faculty Publications
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Item A proposal for a correlation to calculate pressure drop in reticulated porous media with the help of numerical investigation of pressure drop in ideal & randomized reticulated structures(Elsevier Ltd, 2021) Rambabu, S.; Kartik Sriram, K.; Chamarthy, S.; Parthasarathy, P.; Velamati, V.This paper presents a numerical investigation to estimate pressure drop in fluid flow through reticulated ideal and randomized porous structures. The 3D open-cell foam geometries are constructed using an in-house code along with the use of visualization tool kit (VTK) libraries. In this study, the ideal and randomized Kelvin structures with different porosities and pore densities are generated. These structures have been used to perform direct pore level simulations (DPLS) with the aid of a commercial CFD software. The simulation results are used to acquire the pressure drop across the structures. The pressure drop variation with respect to pore density, porosity, specific surface area, and randomization are analyzed and a pressure drop correlation for reticulated structures with new values of viscous and inertial coefficients is proposed. The validity of the proposed correlation is compared against the experimental and numerical data of the real structures that are available in the literature. © 2021 Elsevier LtdItem A numerical study of forced convection in ideal and randomized reticulated porous structures and a proposal for a new correlation(Elsevier Ltd, 2022) Rambabu, S.; Parthasarathy, P.; Velamati, V.This paper presents numerical study to calculate convective heat transfer coefficients in reticulated porous media. In this study, the reticulated porous structures are modelled based on theoretical Kelvin model, representing the real porous structures. The geometry of these structures are generated with the help of in-house code and visualisation tool kit (VTK) libraries. The ideal and randomized Kelvin structures are generated for different PPI & porosities. These structures are utilized to calculate the fluid flow and heat transfer for different fluids of different Prandtl numbers (air, water & sea water). By varying the geometrical parameters, the influence of geometries on heat transfer between the flowing fluid and solid phase of open-cell foams are investigated. For this reason, the momentum and energy equations for forced convection in reticulated structures are solved using standard CFD-FVM approach. Based on the simulation outcomes, a new correlation is proposed to calculate the heat transfer coefficients in the reticulated porous structures. The proposed correlation is validated by comparing it with numerical and experimental data of real reticulated porous structures available in the literature. The effects of the Colburn j factor and performance factor are also computed to obtain the best outcome. © 2021Item Ignition studies of hydrogen-air mixtures over hot wire(Elsevier Ltd, 2023) Velamati, V.; Raj, S.; Parthasarathy, P.; Edacheri Veetil, J.E.Hot surface ignition of combustible gas mixtures poses a safety threat in many engineering applications. Gaseous mixtures ignite when hot surface temperature reaches the ignition threshold. In the present work, two-dimensional numerical simulations with detailed reaction mechanism are performed to simulate the flow of stoichiometric hydrogen-air mixture over a stationary hot wire. The effect of heating rates, wire diameters, mixture inlet velocities, and mixture equivalence ratios on the ignition threshold is investigated. In all the cases investigated, ignition is found to occur at the rear stagnation point, and wire heating rate did not influence the ignition phenomenon significantly. With an increase in mixture inlet velocity and mixture equivalence ratio, the ignition threshold increases, whereas the threshold has been found to decrease with increasing wire diameters. The role of the local equivalence ratios at the ignition point and reaction rates prior to the ignition process has been studied to help better understand the ignition phenomenon under different conditions. © 2022 Hydrogen Energy Publications LLCItem A numerical investigation to determine longitudinal dispersion coefficient in ideal and randomized reticulated porous structures using transient direct pore level simulation(Elsevier Ltd, 2023) Rambabu, S.; Parthasarathy, P.; Velamati, V.The purpose of this numerical investigation is to characterize the longitudinal dispersion coefficients in open-cell reticulated porous structures. Open-cell foams are modelled using idealized Kelvin cell structures. Using the conventional Navier–Stokes equation, airflow has been calculated through various porous structures. Along with the flow, the dispersion of a tracer fluid is traced across the structures and analyzed in terms of the effective dispersion coefficient. Using direct pore level simulations (DPLS), a parametric study is performed to understand the influence of geometrical parameters on the dispersion in porous media. To evaluate the longitudinal dispersion coefficient (LDC), the analytic solution gradients were fitted into the simulated gradients. From the results, a new characteristic length correlation is proposed to calculate the Peclet number, and it is compared with experimental and numerical data that are available in the literature. © 2023 Elsevier LtdItem A numerical study comparing the performance of a self-aspirating domestic LPG porous burner and that of a conventional LPG burner(Elsevier Ltd, 2024) Ranjan, S.; Parthasarathy, P.; Velamati, V.The study involves in the design of a domestic two-layer self-aspirating porous burner that operates at a thermal load of 1 kW using liquefied petroleum gas (LPG). The porous burner is intended to function within India's standard domestic regulator fuel inlet pressure of 3000 Pa. For the same thermal load, this work also provides a numerical comparison between the domestic conventional burner and the designed porous burner. For both porous and conventional burners, a full-scale 3D model is developed to calculate the flow, combustion, heat transfer to the cooking vessel, thermal efficiency, and emissions. The combustion process of both burners is numerically computed using a detailed chemical kinetic mechanism of LPG combustion, the San Diego Mechanism (SDM) with 57 species and 268 reactions are used. The porous burner is simulated using a non-thermal equilibrium condition to better calculate the heat recirculation within the porous domain. The self-aspirated porous burner has an equivalence ratio ? of 0.75 at 1 kW and an efficiency of 84.2%; conventional burner at the same load had an efficiency of 68%. 10 and 6 parts per million (ppm), respectively, are the measured CO and NOx emissions from the domestic porous burner and 660 and 80 ppm for domestic conventional burner, respectively. © 2024 Elsevier Ltd