Research Publications
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Item Mechanical and tribological performance of Al-Fe-SiC-Zr hybrid composites produced through powder metallurgy process(IOP Publishing Ltd, 2021-01-22) Raghav G R; Janardhanan, Sheeja; Chandran, Vidya; V SruthiIn this work a ternary Al-Fe-SiC metal matrix composites were reinforced using Zr particles through powder metallurgy process. The Al matrix and the reinforcements were mixed in high energy ball mill at a speed of 250 rpm over a period of 5 h so as to develop a homogenously dispersed composite material. The composite powders are then pressed at 500 MPa using hydraulic press. The compressed composite green compacts are then sintered at 500 °C for 2 h and allowed to cool under furnace atmosphere. The densities, micro hardness and compressive strength of Al-Fe-SiC-Zr composites were investigated and reported. The composite materials were characterized using SEM, EDS and XRD. The density of Al-10Fe-10SiC-10Zr hybrid composites was found to be around 3.44 g cm−3. The Zr particles have influenced the micro hardness of the composite materials. The micro hardness of the Al-10Fe-10SiC-10Zr hybrid composites was found to be better compared to Al-10Fe and Al-10Fe-10SiC hybrid composites. The compressive strength of the Al-10Fe-10SiC-10Zr hybrid composites was around 205 MPa which is 44% higher than the Al-10Fe composite material. The porosity of the hybrid composites has reduced when compared to that of Al-10Fe and Al-10Fe-10SiC hybrid composites. The wear studies reveal that Al-10Fe-10SiC-10Zr bear out better wear resistance. The predominant wear mechanism was identified as adhesive wear followed by plastic deformation. This improved wear resistance was due to the formation of oxides layers such Al2O3, Fe2O3 and also due to the presence of AlFe3 and Al3Zr4 intermetallics.Item Optimization of a hydro kinetic power generator using genetic algorithm(Spingerlink, 2021-12-27) Viswanath, Anjana; Chandran, Vidya; Janardhanan, SheejaThe paper discusses the optimization of a renewable energy harvester which converts kinetic energy of slow moving currents into electricity. The metaheuristic method of genetic algorithm is adopted to optimize the process parameters of the Hydro Vortex Power Generator (HVPG). The study is conducted in a three folded manner. The device was optimized for the range of Reynolds number 0.3 × 105 < Re < 2.5 × 105 based on equations derived analytically from vibration theory and then using an empirical equation derived from experimental data for two regimes of flow (250 < Re < 3.8 × 104 and 0.3 × 105 < Re < 2.5 × 105. Empirical optimization model is observed to predict the maximum amplitude of oscillation with in a realistic range with the theoretical model showing a three time over prediction. A comparison with experimental results suggests that the effect of added mass on the amplitude of oscillation is of enhanced damping and hence a more realistic prediction is obtained from empirical model optimization. The most significant result from this analysis is that the empirical model predicts maximum amplitude at lowest value of mass ratio (m*), whereas the theoretical model predicts it at the highest value.Item Numerical study on domain independency for prediction of vortex shedding parameters of a circular cylinder(Spingerlink, 2022-04-29) Chandran, Vidya; Janardhanan, Sheeja; Sekar, M.The catastrophes of history make vortex-induced vibration an extensively studied area. The response predictions of offshore and sub-sea structures have gained importance off-late ever since these have been widely used by the petroleum industry. Most of the studies have confined to the comprehension of wake characteristics and the estimation of hydrodynamic loading and shedding parameters of stationary cylinders. Computational fluid dynamics has evolved as one of the effective tools in prediction of response characteristics under vortex shedding and many researchers have studied various aspects of computations that are crucial with reasonable degree of accuracy. This paper addresses the effect of the geometrical shape of fluid domain that encompasses a marine riser during simulations. Four different shapes are analyzed using Reynolds Averaged Navier–Stokes Equation-based commercial solver, ANSYS®. All four domains have the same number of elements, mesh density, and flow Reynolds number (Re). Hydrodynamic force coefficients and frequency of shedding in each case were estimated and compared with previously published numerical and experimental results. It is observed that circular domain is the most efficient in predicting both loading and shedding characteristics with less than 10% deviation as against the theoretical results. Elliptical and square domains failed to capture the vortex shedding phenomenon. The study reveals a significant characteristic of numerical simulations on the modeling and meshing of both near-wall and wake regions.Item Aerodynamic analysis of deployable wing arrangement for space shuttle(Spingerlink, 2022-11-19) Chandran, Vidya; Rajendran, Poornima; Gopakumar, Shabu; Arun Kumar, K. S.; Nikhilraj, C. A.; Janardhanan, SheejaThe study space for morphing wings is astonishingly wide and provides ample scope for enhancements up against fixed wings. Morphing-wing research has accumulated considerable recognition in the aerospace community over the last decade, and a folding wing is a promising approach that can improve aircraft proficiency over multiple varieties of missions which conclusively enhance the capability of the space shuttle. In this paper, the conventional shape of the wings is being refashioned to serve the requirements for maintaining the flight and also for navigation. The idea was sparked by the traditional Japanese fan and has a hinged mechanism similar to that of the fan. This work introduces a novel concept for retractable dynamic wings on a space shuttle. Modeling of the spacecraft with modified wings is done in SOLIDWORKS. The aerodynamic analysis is performed using the computational fluid dynamics (CFD) method with ANSYS FLUENT® (2020 R1) as the solver. The aerodynamic force coefficients are estimated for five different specific deployment phases, viz., zeroth (0°), one quarter (7.5°), half (15°), three-quarter (22.5°), and full (30°) phases. The result reveals that the coefficient of drag drops and the coefficient of lift rises from the primary phase to the final phase providing promising inputs into the idea of retractable wings.Item On the design of a compact emergency mechanical ventilator with negative expiratory exit pressure for COVID-19 patients(Taylor & Francis, 2023-02-17) Janardhanan, Sheeja; Chandran, Vidya; Rajan, RajeshThe present work deals with the design of a cylinder-piston arrangement to deliver the required tidal volume (TV) of air to the patient through the respiratory tract especially in the setting of severe acute respiratory syndrome corona virus 2 (SARS CoV-2) or corona virus disease (COVID-19). The design ensures that only the desired volume of air is delivered in each breath and a negative pressure is retained at the delivery point in a separate cylinder. The frequency of piston motion is the same as that of the average human respiratory rate (RR). The effect of negative pressure on time of evacuation under the present condition has been verified. The present design provides a compact ventilator unit with a surface area of 0.8 × 0.4 m2 with a minimal power requirement of 116.48 W. An RR of 16 is obtained with a volume flow rate in lit/s by using a twin cylinder arrangement with bore diameter 0.1 m and length 0.4 m. The ratio of inspiration time to expiration time is designed to be 1:2 by controlling the stroke frequency as 16 and piston speed 0.32 m/s. The present design provides promising quantitative information on the design of an automated continuous mechanical ventilator (CMV), which is different from bag mask valve (BMV) operated ventilators, and on preventing and minimising barotrauma.