Mechanical Engineering

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This study is focused on harvesting wind energy from gust produced by trains, that are moving inside tunnels by placing Savonius rotors alongside the trains. Numerical simulation shows that the conventional S shaped Savonius rotor fails to harvest energy under such conditions and hence a new design is proposed to generate useful power without compromising the efficiency of the moving trains. The new turbine design is evaluated to optimize its parameters such as diameter and location with respect to train, considering SMRT's (Singapore Mass Rapid Transit) circle line in Singapore. This unconventional energy production can be a viable energy solution to provide power to electronic components and tunnel lighting. © 2018 Elsevier Ltd

(SoE) School of Engineering

Renewable Energy

Modified Savonius wind turbine for harvesting wind energy from trains moving in tunnels

There is a need to explore environment friendly fuels and its' performance for the internal combustion engine due to growing consumption of fossil fuel which is contributing in increasing the air pollution levels of earth atmosphere. The purpose of the study is to optimize the factors which are responsible for the performance of engine as well as emission analysis in case of cassia tora biodiesel blends in direct injection diesel engine using RSM optimization technique. Four input parameters have been considered for the present analysis which includes engine load, injection timing, injection pressure, and blend percentage to optimize engine's performance and emission characteristics. This study includes all factors having five codded levels. RSM is used to get optimum amalgamation of the above stated factors to optimize output variables (UHC, BTE, and NOx). Hence, cassia tora biodiesel may leads in achieving better environmental performance with improved commercial value. The experimental design used in the study is based on central composite rotating design (CCRD) matrix. The best combination of input parameters is recorded at 15 obTDC injection timing of fuel, 221 bar injection pressure of fuel, 40% mixing of cassia tora with diesel, and 47% engine load which results in maximum BTE and minimum UHC and NOx emissions of the engine. Experimental and optimized results of the output responses at optimum input parameters are compared and found to be in the suggested error range. From the future point of view, same work can be extended by utilizing the same biodiesel with some changes in the input parameters and output responses by utilizing the RSM technique and making its comparison with other techniques. © 2018 Elsevier Ltd

World University root node

Energy

Optimization of diesel engine performance and emission parameters employing cassia tora methyl esters-response surface methodology approach

Flying vehicle that is propelled by flapping wings also known as flapping-wing air vehicles (FWAV)/Ornithopters has been a subject of exploration due of its possible use towards unmanned air vehicles (UAV), micro air vehicles (MAVs). Birds and insects fly with unprecedented agility in flight. These FWAVs seek to mimic the motions of such naturally found species. They can find their use in military surveillance or for forestry and wildlife survey. Ornithopters are vehicles that generate the necessary thrust and lift by flapping motion. This exploration work contains a detailed description of the mechanical and the electrical systems used in the FWAV. This paper also focuses on the production process involved in the making of FWAV. This paper also gives an insight about the initial control experiments that were performed. Instead of focusing on problems of small MAV which revolves around miniaturization of the mechanism and electrical energy storage. Our work concerns itself more with the topic of robot locomotion. Thus, it will give details about how one can achieve better stability and control on the flight of an Ornithopter. The developed FWAV has a wingspan of 1.17 m, designed for a kerb weight of 1000 grams. The prototype has been designed specifically for the use of exploration. The designing make extra efforts to enhance payload size, control stabilization, wing efficiency and crash survivability. © Springer Nature Singapore Pte Ltd. 2019.

Lecture Notes in Mechanical Engineering

Designing a biomimetic flapping-wing air vehicle capable of controlled and sustained flight

Multiple voids and cracks were generated during material processing techniques, which interact with each other and affects the service performance of piezoelectric components. This work aims to study the behavior of piezoelectric components in presence of multiple cracks under thermo-electro-mechanical loading environment. Extended finite element method has been implemented to model geometrical discontinuities with crack interaction phenomenon. In this work, thermo-electro- mechanical problem has been decoupled into thermal and electro-elastic problems. Temperature distribution has been obtained by solving heat conduction equation and then used as an input to the electro-elastic problem. In post processing phase, interaction integral method and generalized Stroh formalism were used to predict the stress intensity factors. The methodology has been implemented with in-house developed MATLAB code. Set of cases for crack interaction studies were presented using the proposed approach. © 2018, Springer Nature B.V.

International Journal of Mechanics and Materials in Design

Crack interaction study in piezoelectric materials under thermo-electro-mechanical loading environment

In present work, we investigated the tribological behavior of the high entropy alloy (HEA) claddings under different degrading environments viz, slurry erosion-corrosion, liquid impingement erosion, electrochemical corrosion, and sliding wear. The HEA claddings were developed by varying Al fraction (AlxCoCrFeNi) (x = 0.1 to 3) using microwave processing. The claddings were composed of cellular structure with intermetallic phases segregated in the intercellular region. Variation in Al content showed significant influence on the microstructure and mechanical properties. The hardness of the claddings increased with an increase in Al fraction with a maximum value of 624 HV observed for the cladding containing three molar Al. Correspondingly, the fracture toughness showed an opposing trend. All claddings showed better wear resistance than SS316L with equimolar composition outperforming other counterparts. The equimolar HEA cladding showed 3 to 23 times higher wear resistance compared to SS316L steel depending upon test conditions. Inimitable wear resilience of the equimolar composition was attributed to its high hardness and strain-hardening ability. Surface morphologies of the tested claddings indicated the presence of ductile-brittle mixed damage modes. The tested surfaces showed numerous pits and cracks with delaminated secondary phase. Presence of groves and signs of delamination were also observed in case of sliding wear. The results of the present work show that microwave synthesized equimolar HEAs can effectively counter different tribological forms. © 2019 Elsevier B.V.

Wear

Tribological behavior of microwave synthesized high entropy alloy claddings

Nonrenewable fossil fuels are finite resources that will ultimately deplete in near future. Nature sheds colossal amount of renewable wind energy but humans harvest a morsel. Taking this into account a numerical study is proposed on wind energy harvesting from a speeding subway train. Subways trains generate a remarkable gust of wind that can be transferred to useful electrical energy on daily basis. To this aim, a numerical analysis is modeled by placing Savonius wind turbine in a subway tunnel to crop the wind energy produced from the speeding train. The passage of train in the tunnel generates very high velocity slipstreams along the length of the tunnel. The slipstream phenomena develop a boundary layer regime that will be absorbed by the Savonius wind turbine to self-start and generate power. In the present study, a two-dimensional numerical simulation with modified turbine blade design is carried out using open source tool OpenFOAM® with PimpleDyMFoam solver coupled with six degrees of freedom mesh motion solver sixDoFRigidBodyMotion and k–ɛ turbulence modeling, to measure the amount of torque predicted by the rotor from the gust of wind produced by the speeding train in the tunnel. Being a self-start turbine with no yaw mechanism required the turbine collects air from any direction and converts it into useful power. © IMechE 2018.

Fulltext

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

Improved design of Savonius rotor for green energy production from moving Singapore metropolitan rapid transit train inside tunnel

In the current work we developed Ni-SiC based composite claddings on SS316L through microwave irradiation using different reinforcement weight fractions and particle sizes (micron to nano scale). A bimodal derivative using equal proportions of both micro and nano scale particles was also developed. Microstructural characterization showed claddings were composed of columnar structure with precipitated intermetallic phases segregated at the grain boundaries. The Ni-SiC bimodal particle reinforced claddings showed highest hardness and fracture toughness. All the developed claddings showed significantly high cavitation erosion resistance compared to SS316L steel. The Ni-10 wt\% SiC bimodal particle reinforcement cladding showed highest erosion resistance with around 5 times lower erosion rates than SS316L steel along with highest incubation period. The investigated bimodal particle reinforced cladding also outperformed the thermal sprayed WC10Co4Cr and Stellite 6 coatings and CA6NM hydroturbine steel used for comparison. Detailed structure-property correlation analysis showed that the exquisite performance of the investigated bimodal particle reinforcement cladding can be ascertained to high hardness and H/E ratio (inversely related with plasticity index). Compared to brittle failure mode exhibited by thermal spray coatings due to splat delamination, the Ni-SiC claddings showed mixed signatures of both ductile and brittle failure modes. Examination of the eroded surfaces of the claddings showed presence of significant number of micro pits surrounded by extruded lips and dislodged intracellular phase. Detailed SEM analysis of the samples near incubation period showed damage accumulation initiated around these intermetallic phases in the form of cracks and pits. It was shown that Ni-SiC based microwave-derived bimodal particle reinforced claddings are an effective and efficient solution for countering the cavitation induced erosion in fluid machinery. © 2019 Elsevier B.V.

Microwave synthesized composite claddings with enhanced cavitation erosion resistance

Primary breakup of a liquid jet emanating from a simplex swirl atomizer is numerically studied in this work. The liquid-gas interface is tracked using a coupled Level-Set VOF method. In order to improve the curvature calculation, a dual grid approach is used. Level set function is solved on a grid that is finer than the grid used to solve the rest of the variables. This solver is developed using OpenFOAM libraries and is validated by estimating the pressure profile and spurious velocities across the interface of a static bubble. The validation test shows significant improvement in the performance of curvature estimation without significant increase in the computational cost. Additionally, it is found that curvature calculation improves with increase in grid refinement index. A parametric study to understand the effects of grid refinement index on the flow features of the simplex swirl atomizer primary jet is reported here. Copyright © 2019 ASME

ASME 2019 Gas Turbine India Conference, GTINDIA 2019

Numerical study of primary jet breakup in a simplex swirl atomizer using dual grid coupled level set Vof method

The focus of this work is on the development of asymptotically-accurate nonlinear hyperelastic constitutive model for thin shell structures using Variational Asymptotic Method (VAM). In this work, these structures are analyzed for both geometric and material nonlinearities. The geometric nonlinearity is handled by allowing finite deformations and generalized warping functions through Green strain, while the material nonlinearity is incorporated through strain energy density function of hyperelastic material model. Using the inherent small parameters (moderate strains, very small thickness-to-wavelength ratio and very small thickness-to-initial radius of curvature) for the application of VAM, the process begins with three-dimensional nonlinear hyperelasticity and it weakly decouples the analysis into a one-dimensional through-the-thickness nonlinear analysis and a two-dimensional nonlinear shell analysis. Through-the-thickness analysis is analytical work, providing 3-D warping functions and two-dimensional nonlinear constitutive relation for Nonlinear Finite Element Analysis of shells. Current theory and code are demonstrated through standard test cases and validated with literature. © Springer Nature Switzerland AG 2019.

Advanced Structured Materials

Asymptotically-Accurate Nonlinear Hyperelastic Shell Constitutive Model Using Variational Asymptotic Method

In the present communication, comparison between performance of photovoltaic module with and without duct has been carried out. Different input parameters (namely, ambient air temperature, solar radiation wind speed etc.) have been considered for HT, Delhi campus. Further, thermal modelling has been derived for the c-Si photovoltaic (PV) module alone and PV module with duct. Different parameters like outlet air temperature from duct and cell temperature have been calculated through MATLAB coding. Due to integration of duct, 3.89\% and 125.74\% increase in electrical output and equivalent thermal energy have been found in comparison to stand-alone PV module. © 2019 Elsevier Ltd. All rights reserved.