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

Many numerical models are proposed in the literature using finite element and finite discrete element methods to study fretting wear, barely including the effect of wear debris. These models being computationally expensive, simulating large number of fretting wear cycles is not practically feasible. A new methodology is proposed which needs only bulk material properties like friction/wear coefficients and uses semi-analytical methods to simulate fretting wear with entrapped debris. In this approach, debris are assumed to be attached to one of the surfaces during the fretting process. The results obtained from this approach were compared with fretting experiments. The proposed method permits to capture the wear depth and scar width, and results are very close to that observed in the experiments. © 2016 Elsevier Ltd

World University root node

Tribology International

Semi analytical fretting wear simulation including wear debris

Generally the fatigue life of the components can be improved by introducing compressive residual stresses up to certain depth from the surface. Laser shock processing (LSP) is one of the surface treatment processes to improve fatigue life of the components. When a short duration laser pulse with high power density (more than 1 GW/cm2) irradiates target surface coated with sacrificial layer in a confined medium generally, shock waves are produced. These shock waves deform the target surface plastically and strengthen the material surface up to certain depth to induce residual stresses. LSP improves many properties of the target material such as fatigue life, wear and corrosion resistance, hardness, and etc. This paper reviews the physics involved at all stages of the process generation of plasma at confined medium-material interface and laser induced shock waves, and generation of residual stresses. Also, the effect of various input parameters such as laser parameters, sacrificial layer material, sacrificial layer material thickness, and etc. on residual stress and hardness is discussed. Finally, the applications and challenges of the LSP are also discussed. © 2017 Elsevier Ltd. All rights reserved.

Materials Today: Proceedings

Laser Shock Processing: Process Physics, Parameters, and Applications

Gasketed flange joints are widely used in pressure vessels and piping systems. They are subjected to bending load due to differential thermal expansion, wind load, self-weight, etc., in addition to assembly and internal fluid load. Most of the flange designs are based on equivalent pressure method to include the effect of external bending loads. The behavior of gasketed flange joint is complex due to the nonlinear hysteretic behavior of gasket material and contact interfaces between joint members. It becomes more complex when the joint is subjected to bending load at elevated temperatures. In the present work, performance of a flange joint has been studied under internal pressure and external bending load at elevated temperatures. A 3D finite element model is developed, considering the nonlinearities in the joint due to gasket material and contact between its members along with their temperature-dependent material properties. The performance of joint under different bolt preloads, internal fluid pressures, and temperatures is studied. Flange joint with two gaskets (twin-gasketed flange joint, TGJ) placed concentric is also analyzed. The results from finite element analysis (FEA) are validated using four-point bending test on gasketed flange joint. The sealing and strength criteria are considered to determine the maximum allowable bending moment at different internal fluid temperatures, for both single- and twin-gasketed flange joints with spiral wound gasket. Twin gasket is able to withstand higher bending moment without leakage compared to single gasket. Results show that the allowable load on flange joint depends on operating temperature and gasket configuration. Copyright © 2017 by ASME.

Journal of Pressure Vessel Technology, Transactions of the ASME

A Study on the Behavior of Single- and Twin-Gasketed Flange Joint under External Bending Load

In this article, a generic framework, which takes into account of both the centrifugal and thermal effects, is introduced towards rotordynamic characterization of rotating labyrinth gas turbine seals. A well-established labyrinth seal clearance-leakage model, based on a combined three-dimensional computational fluid dynamics and finite element methodology, along with a second-order rotordynamics model is engaged. The influence of combined centrifugal and thermal radial growth on the rotordynamic characteristics of a generic rotating labyrinth gas turbine seal is explored. For a given rotational speed, the computed rotordynamic seal forces and coefficients, including the stability parameters are compared with the one without considering thermal growth (ambient condition), as a function of pressure ratio and temperature. The results show a significant variation of the crucial seal coefficients with the inclusion of thermal growth and the influence largely varies with both temperature and pressure ratio. Of particular interest is the onset of instability detected at an elevated temperature, regardless of pressure ratio, which necessitates the inclusion of thermal growth so as to avoid early rotor/seal failures. The inherent flow field investigation corroborates well with the rotordynamic characteristics of the seal and its combined centrifugal and thermal effects. © 2017 Elsevier Ltd

International Journal of Mechanical Sciences

Rotordynamic characterization of rotating labyrinth gas turbine seals with radial growth: Combined centrifugal and thermal effects

Owing to increase in the demand for power, a number of power plants have been installed in the recent past. One of the vital components in these plants is gasketed flange joint. The behaviour of gasketed flange joint is highly dependent on the deformation characteristics of gasket material. In the present study, the deformation characteristic of spiral wound gasket along thickness direction is determined experimentally for different loading rates. Gasket has high nonlinearity under both loading and unloading, with hysteresis. Based on its characteristics, the flange joint is analysed to study its performance and leakage behaviour under static condition. 3D finite element model of flange joint is developed by considering the gasket as interface entity. Finite element analysis of flange joint is performed by including the nonlinear hysteretic behaviour of gasket, under different loading rate and frictional contact between joint members. The influence of different loading and unloading rates is emphasized on the sealing performance of flange joint using leakage pressure. The gasket deforms more when loaded at low rate. This phenomenon also affects the ability to withstand internal fluid without leakage. The maximum safe pressure without leakage increases, when gasket is loaded and unloaded at low rate. © Springer Nature Singapore Pte Ltd. 2017.

Lecture Notes in Mechanical Engineering

Influence of loading rate on deformation behaviour and sealing performance of spiral wound gasket in flange joint

A large variety of actuators are used in aerospace applications. They require test benches for qualifying them for flight operation. These test benches are generally of opposing type, where in the actuators are applied opposing loads and the actuators has to prove their capability working against them. Costly Flight load input profile test benches are needed to simulate the actual flight loads including aiding loads to the flight actuators (load applied in the direction of motion of actuator output shaft). This paper presents an idea of using same actuators for both actuator under test (AT) and loading actuator (AL). Both AT and AL will be connected in tandem and load requirements can be met with controlling the current or supply voltage to AL. The required loading direction can be met by advancing or lagging the command to AL in reference with AT. This has many advantages like inherent load, speed, power and bandwidth matching. As both AT and AL are similar, each test run will result in twice the amount of data making it more useful for data intensive experimental prognosis of such systems. The concept is verified with simulation runs on Simulink model representing actual hardware. Experiments are done on analog rotary actuator and linear digital actuators to prove the concept. Current, Voltage and lag controls are experimentally verified for their applicability.

Structural Health Monitoring 2017: Real-Time Material State Awareness and Data-Driven Safety Assurance - Proceedings of the 11th International Workshop on Structural Health Monitoring, IWSHM 2017

New methodology for testing flight actuators in aiding loads catering for large prognosis data needs

The focus of the present work is to develop a robust algorithm for simulation of stationary/moving rigid solid object(s) in free surface flows. The algorithm is based on incompressible finite volume hybrid staggered/non-staggered framework and captures the fluid–fluid interface using the Volume-of-Fluid (VOF) method by solving advection equation for volume fraction with velocity obtained from the Navier–Stokes equations. A novel interface capturing scheme CUIBS (Cubic upwind interpolation blended scheme) is employed to preserve the sharpness of the interface. Presence of the object(s) are accounted through solid fraction, which is advected with the object velocity, either prescribed or calculated from the equations of solid dynamics. A diffuse interface immersed boundary method is employed to solve the normal momentum equation. The present formulation gives liberty to execute normal momentum and pressure correction equation every where in the domain, considering imaginary fluid inside the solid object with dynamic viscosity of heaviest fluid and density of lightest fluid. The algorithm is applied to the benchmark problems involving the flow past a stationary cylinder and water entry of a cylinder. The numerical experiment on the sedimentation of two particles is investigated to analyse the efficacy of present algorithm. © Springer India 2017.

Volume-of-solid immersed boundary method for free surface flows with arbitrary moving rigid bodies

Interfacial phenomena as related to fluid mechanics basically deals with governing laws which determine the behavior of fluids in presence of different phases of matter either similar or dissimilar in constitution, when they are in contact with each other. Such situations often occur in processes and equipments having various industrial applications such as heat pipes, thermal sprays, nebulizers etc. The contact angle provides an inverse measure of wettability. Knowledge of the apparent contact angle and the shape of a drop formed on a substrate are also important in understanding processes such as dropwise condensation, drug delivery, microscale transport physics and adhesive technology, to name a few. The present study seeks to understand and predict drop shapes and their internal pressure for wall bound drops under following configurations: (i) sessile and pendant drops sitting on simple horizontal surface, (ii) drop bound and squeezed by two parallel plates and (iii) drop bound and squeezed by two non-parallel plates.

6th Asian Symposium on Computational Heat Transfer and Fluid Flow

Numerical Prediction and Experimental Validation of Equilibrium Shapes of Wall Bound Drops

Asian Symposium on Computational Heat Transfer and Fluid Flow (ASCHT2017) 10 {\ldots}

Prediction of Production Potential of a Hydrate Reservoir Using Artificial Neural Network

The multi-port burners are utilised in various domestic and industrial heating appliances. The thermal performance of these appliances is usually performed with loading water test. An attempt is made in this work to thermally characterise the methane-air premixed impinging flame jets of multi-port gas burner employing air jet cooling technique. The present method has an advantage that apart from the thermal efficiency, the uniformity in surface heat flux, Nusselt number and effectiveness distributions can be found. The experiments are performed with inline and staggered configurations of multi-port plate burner. The thermal performance for varying mixture Reynolds number, equivalence ratio and burner to plate spacing is presented. The inline configuration performs better in terms of thermal efficiency. However, the staggered configuration produced more uniform surface heat flux. © 2017 Elsevier Ltd