Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
9 results
Search Results
Item Analysis of Cyclic Variations and Combustion Behavior of Liquid Phase Hydrocarbons Under Uniform Axial and Radial Magnetic Fields(Springer Science and Business Media Deutschland GmbH, 2023) Oommen, L.P.; Kumar, G.N.The present study experimentally investigates the combustion characteristics of a multi-cylinder MPFI spark ignition engine fuelled by gasoline under uniform magnetic fields. Permanent magnets made of N38 grade NdFeB are used to magnetize the liquid phase hydrocarbons and the impact produced on combustion characteristics like in-cylinder pressure and net heat release rate are studied under different speeds and load conditions of the engine operation. Three different magnetic intensities (3200 G, 4800 G, and 6400 G) are employed in two different magnetization patterns (axial and radial) at an inbuilt ignition timing of 5 deg bTDC. Magnetic field assisted combustion is observed to enhance the performance characteristics of the engine, while simultaneously reducing the exhaust emissions to a significant level. A statistical analysis of cyclic fluctuations in magnetic field-assisted combustion is also made which shows a reduction in fluctuations (COV) with the application of each stage of ionization. The increase observed in peak pressures and heat release rates along throughout the combustion cycles with reduction in cyclic variations indicate that magnetic field-assisted combustion exhibits better combustion characteristics as compared to normal gasoline combustion. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Experimental Studies on the Effect of Varying Rates of Part-Cooled EGR in High Pressure Loop on an MPFI Engine Under Variable Speed Operation(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Oommen, L.P.; Kumar, G.N.Researches in automobile sector around the globe are focused on meeting the currently proposed emission norms. Exhaust gas recirculation is one pre-treatment technique that has been found effective in enhancing the combustion and emission characteristics of IC engines and regulating the emission of nitrogen oxides. The present work analyses the effect produced by different rates of partially cooled EGR in a high pressure loop on a multi-cylinder MPFI gasoline engine. Three flow rates of EGR—12%, 18% and 24%—have been studied, and the impact produced on thermal efficiency, specific fuel consumption and emission of macropollutants of the test engine has been analysed under variable speed operation in comparison with normal operation of the engine without recirculation. The temperature of recirculated exhaust gas is so maintained as not to have a negative influence on the fuel consumption characteristics. A reduction in specific fuel consumption is observed which results in a marginal improvement of brake thermal efficiency alongside the advantage obtained in the emissions of the engine. The study proves that the advantages of EGR addition are limited to around 18% above to which the cyclic variations and misfires become predominant, deteriorating the performance and emissions of the test engine. © 2021, Springer Nature Singapore Pte Ltd.Item Influence of Magneto-combustion on regulated emissions of an automotive engine under variable speed operation(MechAero Found. for Techn. Res. and Educ. Excellence office@mechaero.org, 2020) Oommen, L.P.; Kumar, G.N.The present study investigates the influence of magneto-combustion on the macro pollutants emitted from a multi point fuel injection (MPFI) automotive engine. The regulated emissions of an auto engine include carbon monoxide, un-burnt hydrocarbon (UBHC)and oxides of nitrogen (NOx) which are the by-products of internal combustion of the hydrocarbon fuel used. Depending upon the physiochemical characteristics of pollutants and their concentrations, these pollutants result in numerous physical ailments and mortality. Magneto-combustion is an under investigated technology which effectively reduces the emission of toxic vehicular exhaust. The exposure to an external magnetic field realigns the hydrocarbon structure and alters its combustion properties. The tests conducted on a Maruthi Zen MPFI engine under two different patterns of magnetisation resulted in a maximum reduction of carbon monoxide by 23.97%, UBHC by 13.1% and NOx by 5.23%, thereby reduced the cumulative negative impact on the environment. © 2020. MechAero Foundation for Technical Research & Education Excellence.Item Experimental studies on the impact of part-cooled high-pressure loop EGR on the combustion and emission characteristics of liquefied petroleum gas(Springer Science and Business Media B.V., 2020) Oommen, L.P.; Kumar, G.N.Liquefied petroleum gas is preferred and adopted in automotive engines because of its efficient burning and cleaner emission characteristics. Since LPG contains less carbon molecules and higher carbon to hydrogen ratios than gasoline or diesel, it has a much higher emission reduction potential both in the cases of regulated and non-regulated emissions. A major disadvantage of deploying LPG widely is the amount of NOx generation owing to the higher temperatures developed in the combustion chamber. In this study, part-cooled EGR is applied in varying rates (12%, 18%, 24%) in order to analyze the effects produced in the performance and emission characteristics of a multicylinder MPFI engine fuelled by 100% LPG at four different loading conditions and four different operating speeds. It can be observed that the application of an optimum rate of cooled EGR reduces the NOx emissions drastically even though at the expense of hydrocarbon emissions. The fuel consumption of the test engine is reduced up to 12.28% with the application of 18% percentage of part-cooled EGR. It can be inferred from the experimental studies that 18% part-cooled EGR is the optimum flow rate of recirculation which is most effective during the part load operation of the engine (50–75%) and at higher engine speeds. However, the emission of oxides of nitrogen reduced by 7.8% at 24% recirculation. The statistical analysis of combustion shows a reduction in combustion stability with increased flow of recirculation. © 2020, Akadémiai Kiadó, Budapest, Hungary.Item Experimental Analysis of Synergetic Effect of Part-Cooled Exhaust Gas Recirculation on Magnetic Field-Assisted Combustion of Liquefied Petroleum Gas(Springer Science and Business Media Deutschland GmbH, 2020) Oommen, L.P.; Gottekere Narayanappa, K.G.; Shivaprasad, S.K.Magnetic field-assisted combustion has been under the focus of research for the last three decades around the globe. The effects of strong uniform and gradient magnetic fields on flame development, behaviour and propagation have been studied, and their applications have been experimented on Internal Combustion Engines. The present work investigates the synergetic effect of part-cooled EGR on the magnetic field-assisted combustion of liquefied petroleum gas in a multicylinder MPFI spark-ignited engine modified for neat LPG operation. Sintered neo-delta magnets with radial magnetization pattern of four different magnetic intensities (0G, 3200G, 4800G and 6400G) are fastened to the fuel line near to the gas injector with a non-magnetic stainless steel integument to prevent any loss of magnetic intensities during the operation. A portion of the exhaust gas is channelled to an intercooler and an optimum percentage of the partially cooled gases are inducted into the inlet manifold for combustion. The experimental study concludes that the optimum flow rate of part-cooled EGR acts synergistically with the applied magnetic fields to enhance the combustion characteristics of LPG emanating an improved fuel economy of 13.8% and brake thermal efficiency of 3.9%. The increased emission of oxides of Nitrogen which is the major setback of LPG combustion can be addressed through the combined effect of part-cooled EGR and magnetic field-assisted combustion. Moreover, the reduction in stability of combustion through the recirculation of exhaust can also be balanced by the applied magnetic field. © 2020, King Fahd University of Petroleum & Minerals.Item Assimilative capacity approach for air pollution control in automotive engines through magnetic field-assisted combustion of hydrocarbons(Springer Science and Business Media Deutschland GmbH, 2021) Oommen, L.P.; Gottekere Narayanappa, K.G.Deterioration of air quality through the combustion of hydrocarbon fuels has been one of the global transboundary problems put before the research community since last five decades. According to the updated statistics, 79% of energy needs in India are met by fossil fuel combustion which results in the emission of toxic pollutants like carbon monoxide, oxides of nitrogen, and unburned hydrocarbons. Air quality has seriously been affected in many parts of India, and statistically, 13 out of 15 most polluted cities in the world lie in India. Magnetic field-assisted combustion has been proven as a reliable technology in internal combustion engines for enhancing the combustion of fuels and reduction of harmful emissions that are the byproducts of incomplete combustion of fuels. In the present work, the magnetic field-assisted combustion of a liquid-phase and a gas-phase fuel (gasoline and LPG) has been studied in a multicylinder automobile engine replicating on road driving conditions in a laboratory focusing on the levels of emissions in comparison with normal combustion of both the fuels. The experimental study concludes that the applied magnetic field positively influences combustion, resulting in reduced level of emission of toxic components irrespective of the phase of hydrocarbon fuels. It is also observed that the percentage reduction in emissions increases with increase in intensity of magnetization. The maximum reduction obtained for CO and UBHC emissions through this technique is 20.58% and 14.47%, respectively. The effectiveness of MFAC in countering air pollution from vehicular exhaust is also studied with respect to fuel phase and mode of operation. The effectiveness of MFAC is observed to be more in high-speed operation of the engine and decreases in the order CO > UBHC > NO. The obtained emission results have a cumulative significance as 45% of total air pollution in India is caused by combustion of hydrocarbons in automotive engines. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.Item Experimental Analysis of Conjoint Effect of Semi-Cooled Exhaust Recirculation on Combustion of Liquid Phase Hydrocarbons Under Uniform Magnetic Fields(Institute for Ionics, 2022) Oommen, L.P.; Kumar, G.N.In the context of increasing the energy utilization of hastily depleting conventional hydrocarbon based fuels and regulating the associated emissions, the present experimental work investigates the conjoint effect of partially cooled exhaust gas recirculation on magnetic field-assisted combustion of gasoline in a multicylinder MPFI spark ignition engine. At the factory set ignition timing of 5 degree BTDC, an optimal mass of burnt gas (18%) within the tolerance limit of the engine determined through prior experiments is recirculated into the combustion chamber after partially cooling in a radiator assembly. The combustible charge which blends with the inert exhaust mixture is prepared from gasoline pretreated under a potent magnetic field generated using NdFeB rare earth magnets capable of enhancing the oxidation process. The intensity of applied magnetic field and the locus of magnetization are decided based on primal experiments. Combustion under the conjoint effect of the set modifications is studied in terms of fuel economy, thermal efficiency and regulated emissions of the engine in which significant improvement is noted. Cyclic variability in combustion is evaluated through the statistical analysis of COV of peak cylinder pressures and mean effective pressures which predicts reduction in probability of misfires. Experimental results portray an enhancement in fuel economy by 14.6% and reduction in cyclic variability by 11.56% under synergy of optimal recirculation and polarization when compared to baseline gasoline combustion and individual impact of recirculation of cooled exhaust gases. © 2022, King Fahd University of Petroleum & Minerals.Item Experimental studies on the influence of axial and radial fields of sintered neo-delta magnets in reforming the energy utilization combustion and emission properties of a hydrocarbon fuel(Taylor and Francis Ltd., 2024) Oommen, L.P.; Kumar, G.N.Permanent magnets based on rare earth components have been increasingly finding their applications in modern technologies. Although the magnetic properties tend to deteriorate rapidly at temperatures in excess of 150ºC, sintered NdFeB magnets can be employed in reforming the physical and combustion properties of hydrocarbon fuels. In the present investigation, two different magnetization patterns of high-grade NdFeB magnets are applied in varying intensities on a multicylinder MPFI engine fueled by gasoline and the alteration in combustion and emission properties of the fuel are studied. The magnetic field restructures the hydrocarbon molecules and causes the pseudo clusters to break away thus reducing the inherent viscosity and enhancing the association of hydrocarbon molecules with the oxidizer. The effectiveness of two different magnetization patterns of sintered NdFeB magnetic material in reforming the combustion characteristics is studied and compared. The study shows a maximum increase of 9.2% in power output and 7.74% in thermal efficiency of the test engine along with a significant reduction in the generation of toxic emissions that are the byproducts of combustion. The study also concludes that radial magnetic fields are more effective in conditioning the fuel and reducing the emission of CO, HC, and NOx by 8.57%, 5.52%, and 1.25% compared to the same intensity fields under axial magnetization. The combustion behavior of gasoline is studied under both field patterns. The statistical analysis of mean effective pressures through radar plots is conclusive of the reduction in cycle by cycle variations under magnetic field-assisted combustion. Abbreviations: NdFeB:Neodymium Iron Boron permanent magnet; SmCo:Samarium Cobalt permanent magnet; MPFI:Multipoint Port Fuel injection; BP:Brake Power; BTE:Brake Thermal Efficiency; BSFC:Brake Specific Fuel Consumption; NHRR:Net Heat Release Rate; IMEP:Indicated Mean Effective Pressure; COV:Coefficient of Variation; CO:Carbon Monoxide; CO2:Carbon dioxide; HC: hydrocarbon; NOxOxides of Nitrogen. © 2020 Taylor & Francis Group, LLC.Item Mitigation of secondary flows and pressure side bubble in turbine blade passage using asymmetric endwall contouring: a steady-state analysis(Institute of Physics, 2025) Babu, S.; Jannet, S.; Raja, R.; Lionel, P.; Oommen, L.P.; Surendran, A.In turbine passages, secondary vortices and pressure-side bubbles significantly contribute to aerodynamic losses and reduced blade efficiency issues that are critical in industrial gas turbine performance. Hence, it is very important to mitigate such losses to enhance overall turbine efficiency. Several research attempts have already been made to address this challenge; however, most studies have not focused explicitly on pressure-side bubble mitigation strategies. In the present investigation, an effort has been made to investigate the impact of endwall contouring in minimizing losses caused by secondary vortices, particularly focusing on pressure-side bubble formation. Experimental and numerical investigations are conducted on a low-speed blowing-type turbine cascade wind tunnel. The experimental study involves in-cascade testing, while numerical simulations are performed using ANSYS Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear Stress Transport (SST) turbulence model. Three contouring configurations (EC 1, EC 2, and EC 3) are compared against a non-profiled base case (BC). The results confirm that endwall curvature significantly alters secondary flow behavior and static pressure distribution. While EC 1 and EC 2 generated stagnant zones in the valleys, causing additional losses while the EC 3 profile with optimized hump height and valley depth, redistributed pressure effectively. This effectively suppressed lateral flow migration and pressure-side bubble formation, which in turn enhanced overall turbine performance. In comparison to the base case, the EC 3 design quantitatively reduced total pressure loss by 3.43%, proving its efficacy in improving aerodynamic performance. © 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.