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

Abstract Heat transfer from perforated plate burner flame impinging on a flat plate finds importance in industrial (gas fired boiler) and domestic heating (household gas burner and commercial hotel gas burners) applications. A limited study on heat transfer distribution of this kind of burner plate is found in the literature. In the present work, high resolution heat flux is estimated by the inverse heat conduction (IHCP) technique based on use of analytical solution for semi-infinite medium for the impingement plate. Inline, star and staggered holes patterns with three different inter-hole distances (pitch) are considered in the present study. Methane-air premixed flame of Reynolds number varying from 50 to 600 and an equivalence ratio varying from 0.6 to 1.2 is considered. The hole to impingement plate distance is varied from 3 to 7. From the experimental results, it is found that the inline and staggered patterns have the same heat flux averaged over an area of 50 mm × 50 mm for different Reynolds number. The intermediate pitch of 7 mm is the optimal pitch over the entire mixture flow range considered in the present study. The specific fuel consumption for the star pattern is less by 40-60% as compared with the inline pattern for p/d Combining double low line 1.67, Re Combining double low line 50-300 and z/d Combining double low line 3-7. A numerical simulation is carried out using CFD software to explain the shift in the peak heat flux away from the geometric intended location. © 2015 Elsevier Masson SAS. All rights reserved.

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International Journal of Thermal Sciences

An experimental and numerical investigation of heat transfer distribution of perforated plate burner flames impinging on a flat plate

Energy from spent flame or other low grade energy can be used to increase the temperature of the air before mixing with fuel. This would improve the heat transfer characteristics of the impinging flame jet. The studies on impinging flame jets reported in the literature are based on the fuel-air mixture at ambient temperature. In the present work, the inlet air for mixture is heated by an electrical heater. The heat flux distribution is estimated using an inverse heat conduction (IHCP) technique. The Nusselt number (Nu) and effectiveness (η) distributions are obtained by estimating the adiabatic wall temperature (Taw) by the analytical-numerical method. A circular burner of 13.5 mm is used for impingement on quartz plate of 3 mm thickness. Reynolds number (Re) varying from 500 to 2000 for the non-dimensional burner tip to impingement plate spacing (Z/d) of 2-6 and stoichiometric condition (Ø = 1.0) is considered for varying preheated condition. The effect of equivalence ratio is studied for Ø = 0.75 to 1.5 for Re = 1000 and Z/d = 4. By increase in preheat temperature, the stagnation point heat flux increases from 20% to 50% unless the inner premixed zone touches the impingement plate. CFD simulations are carried out in FLUENT software to explain the distribution of heat flux. © 2015 Elsevier Ltd. All rights reserved.

International Journal of Heat and Mass Transfer

Effect of preheated mixture on heat transfer characteristics of impinging methane-air premixed flame jet

Inconel 706 is a newly developed superalloy, which offers high mechanical strength alongwith easy fabricability thus making it suitable for turbine disk applications. Although Inconel 706 exhibits a substantial increase in stress rupture and tensile yield strength compared to other superalloys, its conventional machining yields poor surface finish and low dimensional accuracy of the machined components. Hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed and various performance attributes such as material removal rate (MRR), surface roughness (SR), recast surface, topography, microhardness, microstructural and metallurgical changes of the machined components have been evaluated. The experimental results revealed that servo voltage, pulse on time, and pulse off time greatly influence the MRR and SR. Due to high toughness of Inconel 706, no micro cracks were observed on the machined surface. Micro voids and micro globules are significantly reduced at low pulse on time and high servo voltage. But, there is a propensity of thick recast layer formation at high pulse on time and low servo voltage. EDAX analysis of recast surface exposed the existence of Cu and Zn which have migrated from the brass wire. The subsurface microhardness was changed to 80. μm due to significant thermal degradation. © 2015 Elsevier Ltd.

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Materials and Design

Evaluation of WEDM performance characteristics of Inconel 706 for turbine disk application

Every year, large numbers of two wheelers are sold in India and other Asian countries. A majority of these engines still tend to be carbureted due to cost and fuel quality issues. As an alternative to the carburetor, port fuel injectors (PFI) have started being introduced in the last few years for small two wheeler vehicles. Although PFI systems offer better metering of fuel and better transient response compared to carbureted systems, they are more expensive and require more power to pressurize the fuel. More importantly, wall film formation is observed in both the technologies, which reduces the effectiveness of the PFI system. Hence, a new technology is proposed which includes a PFI system along with an ultrasonic atomizer. The purpose of the proposed system is to improve the transient response and hence improve the fuel economy of gasoline engines and lower the emissions especially under cold conditions. The proposed concept was tested standalone on a laboratory setup. A transparent duct of square section was fabricated and fuel was injected in it. High speed schlieren imaging was done to qualitatively visualize the vapor concentration in the proposed system compared to a conventional port fuel injection system. Mass measurement of the fuel atomized was done to quantitatively characterize the proposed system. The proposed system was found to be better than the existing conventional PFI system. It has metering capability like PFI with potentially better transient response at a similar cost. Copyright © 2015 SAE Japan and Copyright © 2015 SAE International.

SAE Technical Paper

A Novel Concept for Mixture Preparation in Port Fuel Injected Engines

Studies on the evaporation of suspended microlitre droplets under atmospheric conditions have observed faster evaporation rates than the theoretical diffusion-driven rate, especially for rapidly evaporating droplets such as ethanol. Convective flow inside rapidly evaporating droplets has also been reported in the literature. The surrounding gas around the evaporating droplet has, however, been considered to be quiescent in many studies, the validity of which can be questioned. In the present work, we try to answer this question by direct experimental observation of the flow. The possible causes of such a flow are also explored. © 2015 AIP Publishing LLC.

Physics of Fluids

Evaporation-induced flow around a pendant droplet and its influence on evaporation

In the present work, a pilot scale atomization setup is built to atomize low melting point material like tin under the influence of high speed nitrogen gas coming out from an annular free-fall nozzle. The aim is to directly visualize the primary and secondary breakup of liquid tin using high speed shadow imaging technique. The visualization of secondary breakup alone is reported in the present work. Irrespective of the type of nozzle, very little experimental information of secondary breakup mechanism of liquid metal is available. The visualization done in the present pilot setup shows secondary breakup even very close to the tip of the melt nozzle. Secondary atomization in this region takes place through bag breakup and stripping breakup mechanism. Secondary breakup little away from the melt nozzle tip occurs predominantly through bag breakup mode. An approximate estimation of Weber number supports the regime of breakup as observed here. © 2015 International Conference on Liquid Atomization and Spray Systems. All rights reserved.

ICLASS 2015 - 13th International Conference on Liquid Atomization and Spray Systems

Visualization of secondary breakup of liquid tin during powder production

Fringe tracking and fringe order assignment have become the central topics of current research in digital photoelasticity. Isotropic points (IPs) appearing in low fringe order zones are often either overlooked or entirely missed in conventional as well as digital photoelasticity. We aim to highlight image processing for characterizing IPs in an isochromatic fringe field. By resorting to a global analytical solution of a circular disk, sensitivity of IPs to small changes in far-field loading on the disk is highlighted. A local theory supplements the global closed-form solutions of three-, four-, and six-point loading configurations of circular disk. The local theoretical concepts developed in this paper are demonstrated through digital image analysis of isochromatics in circular disks subjected to three- and four-point loads. © 2015 Society of Photo-Optical Instrumentation Engineers.

Optical Engineering

Digital image analysis around isotropic points for photoelastic pattern recognition

24th National Conference on IC Engines and Combustion

Numerical studies on Trapped Vortex Combustor with Syngas fuel

In this work, a simple and efficient numerical approach to determine the shape of the minimum-drag axisymmetric forebody in inviscid supersonic flow with an attached shock constraint has been described. Taylor–Maccoll equation in conjunction with the tangent cone method is employed to estimate the pressure drag coefficient which is also chosen as the cost function. The forebody geometry is parameterized using a Non-Uniform Rational B-Splines (NURBS) curve whose control points are the design variables for optimisation using the steepest descent algorithm. Numerical studies demonstrate that the optimal forebody geometry for a given length and base radius has as much as 15 % lesser drag, depending on the Mach number than a cone of the same fineness ratio and that the convergence to the optimal solution exhibits a relatively weak Mach-number dependence. © 2014, The Institution of Engineers (India).

Journal of The Institution of Engineers (India): Series C

Optimal Forebody Shape for Minimum Drag in Supersonic Flow

The dynamic analysis of wind turbine drive train is presented in this paper. A typical wind turbine drive train consists of a rotor, gearbox and generator. The dynamic modelling of epicyclic gearbox that exists in wind turbine is challenging due to the fact that it has both rotating and orbiting gears. The dynamic equations of motion are obtained based on the rigid multibody modelling with discrete flexibility approach by Lagrange's formulation. The dynamic model accounts for the time varying gear tooth mesh stiffness, linear stiffness of bearings and torsional shaft stiffness. The aerodynamic torque that a wind turbine drive train subjected to, is modelled based on the simplified method for load calculation in wind turbine, Danish Standard DS472. The characteristic load value acting per unit length at the two-thirds length of the blade is used for calculating the total load of the torsional moment. The vibration signals that are obtained from wind turbine drive train are nonlinear and nonstationary in nature. This is due to the fact that the applied torque load on drive train is nonlinear and nonstationary in nature. The coupled dynamic model of 18 degrees of freedom is solved for responses in time and frequency domains for some nonstationary wind load realizations. The dynamic responses of the system, contact forces between gear tooth pairs in time and frequency domains are obtained numerically. The study envisages that this dynamic model of wind turbine drive train is very useful for subsequent studies on condition monitoring. © IMechE 2014.