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

Multi-port curved surface burners are used in industrial boilers, preheating of large diameter pipes, textile industries, preheating of cylindrical metal billets and other industrial applications. The present work reports the heat transfer characteristics of convex shaped burner with 49 inline ports arranged in an array of 7 each. The methane-air premixed flame jets are impinged on the concave surface of a curved plate placed with radial spacing of 12 mm. Two different burners with port diameters of 2 mm and 3 mm with pitch to diameter ratio of 2.33 are used. The flame jet is studied for Reynolds number (Re) ranging from 75 to 200 and equivalence ratio of 0.9–1.5. The characterisation is done by impinging the pre-characterised air jets of various flow rates on the rear surface and capturing the wall temperature. The wall temperature is analysed to get the distributions of Nusselt number and effectiveness. The variation of coefficient of variance of Nusselt number, average Nusselt number and thermal efficiency is reported in the present work. The Nusselt number and effectiveness distributions increase with the increase in mixture Reynolds number. For a fixed mixture Reynolds number, the optimum heat transfer is obtained for stoichiometric flame. The thermal efficiency and average heat transfer of 2 mm port diameter is observed to be 18–25% higher as compared with burner with port diameter of 3 mm. Correlations are developed to predict the average Nusselt number, average effectiveness, coefficient of variance (COV) of Nusselt number distribution and thermal efficiency.

World University root node

Applied Thermal Engineering

Heat transfer investigations on impinging flame jets of a multi-port convex burner

Transient operating conditions such as run-up and run-down are often seen in automotive and other machines with variable speed rotating elements. To estimate the frequency response function from swept sine responses (obtained during run-up), a new approach is proposed which utilizes Hilbert transform and stationary wavelet transform. This method is an alternate tool for conventional swept sine frequency response function estimators like tracking vectors and co-quad analysers. The output from this algorithm is validated using frequency response function obtained using exact frequency response function expression and the conventional Fourier transform-based frequency response function. Both MATLAB simulations and experiments have been carried out in this study to estimate the frequency response function. Modal parameters are extracted from the frequency response function obtained using Hilbert transform. © 2017, IMechE 2017.

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

Hilbert transform-based frequency response function estimation from run-up response of rotors

Many rotating machinery components fail due to fatigue when subjected to continuous fluctuating stresses. Hence, estimation of fatigue crack initiation life is essential to avoid catastrophic failure. Effective vibration based fatigue life analysis requires measurement of accurate time varying signal. In this study, experimentally observed fatigue lives of rotating shaft, for three different notch configurations, are compared with fatigue lives estimated using two approaches based on an acquired vibration signal. The first one is time domain approach (based on Rainflow cycle counting) while the second one is frequency domain approach (based on power spectral density moments). In the frequency domain approach, fatigue life is estimated using the narrow-band approximation and Dirlik’s empirical solution. The performance of two approaches in estimating fatigue life for the same signal length taken at different time intervals from the total signal acquired is also discussed. In addition, experimental uncertainty analysis is performed and discussed in this study. A good correlation is found between the estimated fatigue life using Dirlik’s rainflow range probability density function and experimental life. Therefore, this study concludes that the Dirlik’s approach can be considered as preferable method for estimating fatigue life of rotating shaft. © 2018, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.

Journal of Mechanical Science and Technology

Life estimation of shafts using vibration based fatigue analysis

Pre-prints of the National Meeting of Japan Welding Society

Effect of plate thickness on tool life in FSW of high strength aluminum alloy

Electrical discharge machining (EDM) is a non-contact machining process that removes material through spark erosion and is often used for drilling holes in difficult-to-cut materials such as Nickel-based super alloys. However, this process becomes slower with the increase of the hole depth. This is because the flushing pressure becomes inefficient for the effective evacuation of process debris leading to secondary discharges and resulting in increased machining time. This study presents an innovative simultaneous flushing and vacuum-assisted debris removal system, which facilitates better debris removal for deep-hole EDM drilling. Improvement in the drilling time and better surface roughness have been achieved using the developed setup. To evaluate the performance of the vacuum-assisted debris removal system, a novel computational fluid dynamics model is also proposed in this study. Experimentally measured particle size data of full length scale act as a reference for the proposed numerical model.The analysis presented in this study provides significant insight into sizes of the debris particles in different machining conditions, in full length scale using an automated image processing technique. The presented numerical model can be used to investigate the various factors influencing the removal of debris from the machining zone. The experimental and numerical components of this research complement each other in the design of the presented vacuum-assisted debris removal system. © 2017 Elsevier B.V.

Journal of Materials Processing Technology

A study on EDM debris particle size and flushing mechanism for efficient debris removal in EDM-drilling of Inconel 718

This paper presents a dual-loop control scheme based on an integral sliding mode control scheme for the task-space pose error correction in trajectory-tracking of a planar 3-PRP parallel manipulator due to mechanical inaccuracies. The proposed dual-loop control scheme uses redundant sensor feedback, i.e., individual active joint displacements, velocities (at the joint-space level) and, end-effector positions and orientation (at the task-space level) are obtained as feedback signals using appropriate sensors. Using the redundant feedback information, the actual pose errors of the end-effector are computed in the outer-loop (kinematic) control and rectified in joint-space inner-loop (dynamic) control to achieve the given desired task-space trajectory. To demonstrate the efficacy and show complete performance of the controllers, real-time experiments are executed on an in-house fabricated planar 3-PRP parallel manipulator. The experimentation results show that the manipulator tracing performance is considerably improved with the proposed dual-loop control scheme. In addition, the controller parameter sensitivity and robustness analyses are also accomplished. © 2017, Springer Science+Business Media Dordrecht.

Journal of Intelligent and Robotic Systems: Theory and Applications

Dual Integral Sliding Mode Control Loop for Mechanical Error Correction in Trajectory-Tracking of a Planar 3-PRP Parallel Manipulator

This paper addresses the dimensional synthesis and design optimization of a three-degree-of-freedom planar U-shape fixed base 2PRP-PRR parallel manipulator to maximize its workspace. Two kinematic design solutions are proposed and their link parameters are optimized to maximize the workspace. Furthermore, accuracy analysis of the optimized manipulator configurations for the actuator inaccuracies is performed and the results are compared with the well-known planar 3PRP and 2PRP-PPR parallel configurations. © Springer International Publishing AG 2018.

Mechanisms and Machine Science

Design optimization and accuracy analysis of a planar 2PRP-PRR parallel manipulator

The present study considers the mixing characteristics of gaseous species in a channel with wavy walls. Waviness imparted along the walls are uniquely defined by the wavelength (λ), amplitude (a) and phase difference (PD). A quasi-incompressible formulation in a three-dimensional collocated finite volume framework is employed for the numerical simulations. Results show that wavy channels lead to enhanced mixing, quantified by the mixing efficiency (M), compared to that of a plane channel. Moreover, the use of asymmetric channels (with 0° PD) shows better mixing capability than their symmetric counterparts (with 180° PD) for same wavelength and amplitude. We argue, based on numerical results that the enhanced mixing in the asymmetric channels is due to the generation of alternate recirculation patterns, leading to higher transverse velocities. These transverse convective currents combined with diffusion are observed to aid the mixing process. A complete set of parametric studies is subsequently carried out to investigate the effect of the geometric parameters of waves along with Reynolds number, Peclet number for the 0° PD wavy channel. It is observed that for a given length, there exists a critical wave number that maximizes the mixing efficiency. © 2018 Elsevier B.V.

Chemical Engineering and Processing - Process Intensification

Numerical investigation of mixing enhancement for multi-species flows in wavy channels

This paper reports results of an experimental study on various fluid patterns produced by two symmetric impinging Newtonian liquid jets. Water–glycerol mixtures with viscosities of 5 mPa·s, 15 mPa·s and 40 mPa·s were used to study the effect of viscosity on fluid patterns. Two liquid jets with a diameter of 0.76 mm each were made to impinge on each other. Images in the plane perpendicular to both liquid jets were captured using a backlight direct imaging method using a 4 MPixel CCD camera. New types of periodic patterns, which to date have not been reported for Newtonian liquids, were observed in this study. It was observed that the velocity at which periodic patterns start to appear depends on the liquid viscosity. A fish-bone-like periodic structure was observed only with the 5 mPa·s liquid, while periodic shedding of droplets from the rim is not observed with the 40 mPa·s viscosity liquid. Periodic patterns were observed for all the liquids only at an impinging angle of 60 o , unlike in earlier studies where the patterns were observed with an impinging angle of 90 o . It was also observed that significant asymmetry between the liquid jets is not necessary for the formation of periodic patterns. © 2018 by Begell House, Inc.

Journal of Flow Visualization and Image Processing

ATOMIZATION PATTERNS PRODUCED BY VISCOUS, LIKE-ON-LIKE IMPINGING LIQUID JETS

Nowadays, metal cutting industries are looking towards new sustainable manufacturing methods to reach the target set by the environmentally conscious regulations in terms of usage and disposal of chemical contaminant conventional coolants without sacrificing the productivity. Machining with cryogenic coolants is an efficient, emerging sustainable manufacturing process. In the current work, a low cost external spray cooling cryogenic machining setup has been developed to spray the cryogenic coolant at the machining zone. In the current work, cryogenic coolant (liquid nitrogen) was used to machine the 17-4 precipitated hardenable stainless steel (PH SS) at varying depth of cut conditions and the results were compared with a minimum quantity lubrication (MQL), wet and dry machining environments. The investigative parameters considered in the present study were cutting temperature, tool wear (flank and rake), surface integrity (surface roughness and surface topography) and chip morphology. Cryogenic machining has given beneficial results compared to other machining environments. Hence, cryogenic machining is the most promising technique for machining of 17-4 PH SS. From the health and environmental point of view, cryogenic machining is a clean manufacturing technique. © 2018 CIRP

CIRP Journal of Manufacturing Science and Technology

Effect of cryogenic coolant on turning performance characteristics during machining of 17-4 PH stainless steel: A comparison with MQL, wet, dry machining