Department of Mechanical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In this study 6 mm thick plates of aluminum matrix composites (AMCs) composed of AA6061/SiC (10 Wt. %) /fly ash (7.5 Wt. %) were butt welded using friction stir welding (FSW. Microstructural characterization of weld joints was conducted by using optical microscopy (OM) and scanning electron microscopy (SEM). The microstructure of the weld revealed the presence of four different zones like nugget zone (NZ), thermo mechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal (BM). Nugget zone reveals homogenous distribution of fly ash and SiC particles. Rotating effect of FSW tool results in breaking of some array of grains present in the parent AMCs. Needle like phases present in the parent AMCs eliminated successfully by the incorporation of fly ash particles. Higher hardness is observed in the nugget zone compared to other zones. © 2018 Elsevier Ltd. All rights reserved.

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Materials Today: Proceedings

Effect of FSW on microstructure and hardness of AA6061/SiC/fly ash MMCs

The present work investigates buoyancy induced cooling of the vertical rods in an enclosure under the influence of radiative heat transfer using a non-Boussinesq model. The problem consists of seven vertical fuel rods placed in a cylindrical casing which is typically encountered in the nuclear engineering application. Combined convective-radiative heat transfer is studied for uniform heated rod bundle housed in an outer cylindrical casing maintained at a constant temperature. The present study is carried out using an in-house three-dimensional solver by employing a low-Mach number formulation based on unstructured hybrid grids. Simulations considering pure natural convection and combined convection with surface radiation is studied. The heat transfer characteristics concerning temperature distribution inside the enclosure are studied by including the effects of surface radiation. © 2018 International Heat Transfer Conference. All rights reserved.

International Heat Transfer Conference

Three-dimensional analysis of non-Boussinesq natural convection with radiative heat transfer in a vertical seven rod bundle

Leakage is the main mode of failure in gasketed flange joints used in nuclear and thermal power plants. The leakage occurs when the joint is not able to withstand the internal fluid pressure. To evaluate the leakage behavior of gasketed flange joint, it is important to incorporate gasket properties and interfacial contact behavior due to friction. However, for safe joint operation, the members also should be structurally sound without exceeding allowable limit of materials. In this study, the joint strength and sealing behavior of gasketed flange joint are investigated through experiments by carrying out leakage test. The joint strength is evaluated based on strains developed in flanges along longitudinal and tangential direction under both pretightening and pressurizing stages. Three-dimensional finite element simulation is also performed under both aforesaid stages, considering the nonlinear properties of gasket along with hysteresis during unloading. The finite element results of joint strength and leakage pressure are compared with experimental values and observed to be conservative. In addition, the performance of twin gaskets (two gaskets concentric to each other) through both experiment and simulation is also evaluated and compared with that of the single gasket. From the experiment and finite element analysis, it is found that the sealability of twin-gasketed joint is higher than that of single-gasketed joint. © IMechE 2017.

Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering

Studies on joint strength and sealing behavior of single and twin-gasketed flange joints

Cryogenic machining is one of the environmental friendly machining techniques offers high productivity in machining of difficult to cut materials. The present article investigates the multi response optimization in turning of 17-4 Precipitation Hardened Stainless Steel (PH SS) under the jetting of cryogenic coolant (liquid nitrogen) on the rake face of the cutting tool using Taguchi coupled grey relational analysis (TGRA). Cutting velocity, feed rate and depth of cut were considered as the controllable process parameters. Cutting force, surface roughness, tool flank wear and material removal rate (MRR) were considered as the performance characteristics. Experiments were performed based on Taguchi L 9 orthogonal array. From the TGRA result, it was found that at cutting velocity of 120.89 m/min, feed rate at 0.048 mm/rev and depth of cut 0.4 mm obtained the improved turning process performance characteristics. Scanning electron microscope (SEM) has been used to obtain the tool flank wear and machined surface images at the optimum machining conditions. Further analysis of variance (ANOVA) has been carried out and it was identified that feed rate was most influencing process parameter contributing 53.76% on the multi performance characteristics. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

Advances in Materials and Processing Technologies

Multi performance characteristics optimization in cryogenic turning of 17-4 PH stainless steel using Taguchi coupled grey relational analysis

The high heat transfer rates from impinging flame jets and plumes are extensively used in many industrial applications. Comprehensive literature review suggests that the characterization of flame impingement is done primarily by the measurement of heat flux onto the target surface. The use of in-situ probes limits the spatial resolution of the measurement. For a diffusion flame, radiation cannot be neglected and it is therefore necessary to determine the convective and radiative heat flux components to quantify the thermal boundary condition to the impingement surface. For determining the heat transfer characteristics of impinging diffusion flames, the target surface is impinged by a methane diffusion flame from the bottom and is simultaneously cooled from the top by air jets of different Reynolds number. At steady state, one dimensional energy balance across the impingement surface provides an equation with the three unknowns being the heat transfer coefficient of the flame jet, the reference temperature and the emissivity of the gas/flame. By keeping the flame jet impingement conditions same and varying the air jet impingement on the top surface, five different forms of the energy balance equation is obtained. A minimization technique, that makes use of the Nelder-Mead algorithm, is developed to solve for the over-determined system of equations. The obtained results are compared with the slope method that determines the effective heat transfer coefficient and the reference temperature. The impingement surface is modeled in FLUENT and the experimentally obtained heat transfer coefficient of the flame jet, the reference temperature and the emissivity of the gas/flame is provided as the boundary condition to numerically determine the surface temperature. For validation purpose, the impingement surface material and thickness is changed and the experimentally obtained and numerically determined wall temperatures are compared. It is demonstrated that the minimization technique is capable of separating the convective and radiative heat transfer components from impinging diffusion flames. © 2018 Elsevier Ltd

International Journal of Heat and Mass Transfer

Separation of heat transfer components from impinging methane diffusion flames

The flame jet impingement on curved surfaces finds applications in various direct flame heating situations. The design of heating equipment demands the estimation of the surface temperature and of the convective heat flux to the target surface at steady state for various impingement parameters. The characterisation of flame jets in terms of Nusselt number and effectiveness aids the designer to numerically estimate the steady state surface temperature and heat flux by specifying the convective boundary condition with spatial distribution of reference temperature. The present study reports the heat transfer characteristics of single flame jet impinging on convex and concave surfaces of a semi-cylindrical target plate. The effects of mixture Reynolds number, equivalence ratio, curvature ratio and burner to plate spacing on the heat transfer behavior are investigated. The uniformity of the heat flux distribution and the overall thermal efficiency are determined from the local heat flux distributions. The flow fields along the curvilinear axes influence the overall thermal performance. The concave surface produces higher thermal efficiency and better uniformity of heat flux over the impingement surface as compared with the convex surface. © 2018 Elsevier Masson SAS

International Journal of Thermal Sciences

Heat transfer investigations on methane-air premixed flame jet exiting from a circular nozzle and impinging over semi-cylindrical surfaces

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Biophysical Journal

Interplay of Curvature Sensing and Generation Mediated by Peripheral Membrane Proteins

Inconel 718 is one of the most widely used super alloys in industries like oil and gas, aerospace and automobile. However, properties like poor thermal conductivity and work hardening tendency make it difficult to machine, using a conventional machining approach. EDM is one of the effective and efficient ways of machining this exotic material. However, the material removal rate (MRR) is very low. In an attempt to enhance the performance of EDM, an arc machining module has been integrated into the existing EDM system and the compound process is named hybrid electrical discharge and arc machining (HEDAM). Due to the high thermal intensity of the sparks/arcs imparted by this process, the material removal rate is elevated. To understand this process better, a comparative thermal modelling between HEDAM and EDM has been presented in this article. Firstly, a thermal analysis is performed for the EDM and HEDAM processes to understand their respective erosion efficiencies. Finally, the numerical simulation for MRR of both EDM and HEDAM is presented. Unlike other EDM models, in this simulation, the thermophysical properties of the material were considered to be temperature-dependent and the latent heat of fusion was incorporated into the modelling process. A comparative analysis was also performed, which showed that incorporating such variables increases the accuracy of the obtained results. The study revealed that the spark radius in HEDAM is larger in size and more stable. Consequently, this resulted in HEDAM to have about three times more erosion efficiency compared to conventional EDM. © 2017, Springer-Verlag London Ltd.

International Journal of Advanced Manufacturing Technology

A comparative study on the modelling of EDM and hybrid electrical discharge and arc machining considering latent heat and temperature-dependent properties of Inconel 718

This paper presents an analytical error prediction model of a 3PRP planar parallel manipulator using the screw theory. This analytical approach is used to find the effect of mechanical inaccuracies contributing to the end-effector pose errors and their sensitivity coefficients. Finally, parameter sensitivity analysis of non-compensable errors of two different configurations based on their fixed base shape namely ∆-shape and U-shape fixed bases are analysed and compared. © Springer International Publishing AG 2018.

Mechanisms and Machine Science

Error modelling and sensitivity analysis of a planar 3-PRP parallel manipulator

The present work numerically investigates the influence of partitions on buoyancy induced convection with thermal radiation in a differentially heated cubical enclosure. Four distinct arrangements of partitions from the top-bottom and front-back walls are examined by adopting a symmetric (inline) and asymmetric (offset) configuration of partitions. An in-house three-dimensional numerical solver based on low-Mach number formulation is employed for the numerical simulations of high-temperature natural convection as well as combined convection with surface and gas radiation. Comparative analysis of average and local Nusselt number variation at the isothermal walls and temperature variation inside the enclosure is presented for all configurations of partitions considered. Irreversibilities associated with conduction, convection, and radiation heat transfer with viscous dissipation are studied to investigate the role of partitioning walls in overall volumetric entropy production. This study also aims at determining the optimum design (higher heat transfer rates with minimum entropy production) among all partition configurations. The simulation results reveal that heat transfer irreversibility is the dominant mechanism of entropy production. Furthermore, offset configuration of front-back partitions could be a preferred choice in the practical design of buildings where the impact of combined convective-radiative heat transfer is significant. © 2018 Elsevier Ltd