Mechanical Engineering

Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.

Shiv Nadar University

Cavitation erosion remains the primary cause of material degradation in fluid machinery components operating at high speed. Micro-jets/shock waves caused by implosion of bubbles on material surface results in significant material loss and premature failure of the components. The presence of corrosive medium further exuberates this effect, causing rapid degradation. Here, we demonstrate a novel pathway to control cavitation erosion-corrosion by tailoring the surface properties using submerged friction stir processing (FSP), a severe plastic deformation process. FSP parameters were varied over wide range of strain-rates to generate tailored microstructures. High strain-rate processing resulted in nearly single phase fine grained structure while low strain-rate processing resulted in phase transformation in addition to grain refinement. As-received and processed samples were subjected to ultrasonic cavitation in distilled water as well as in corrosive environment of 3.5\% NaCl solution. Individual roles of cavitation erosion, corrosion and their synergistic effects were analyzed. Depending on the microstructure, processed samples showed nearly 4–6 times higher cavitation erosion resistance compared to as-received alloy. Superior cavitation erosion-corrosion resistance of processed samples was attributed to surface strengthening, higher strain-hardening ability and quick passivation kinetics. The results of current study could be potentially transformative in designing robust materials for hydro-dynamic applications. © 2018 Elsevier B.V.

(SoE) School of Engineering

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Ultrasonics Sonochemistry

Ultrasonic cavitation erosion-corrosion behavior of friction stir processed stainless steel

The development of cleaner and renewable energy sources are necessary so that fossil fuel dependency and global warming can be reduced. Present communication is an attempt to explore the available literature on Photovoltaic Thermal (PVT) air collectors and PVT air collector integrated greenhouse drying system. Solar drying is one of the best method to preserve crops for a long time. In developing and under developed countries; per capita electricity production is low; therefore the electricity uses for heating purpose cannot be economically and environmentally justified option. In previous studies, it was found that forced drying is better in terms of controlling drying parameters and PVT air collector is better than standalone PV module in terms of energy storage. In present review paper, combination of PVT air collector and drying system has been discussed. Moreover, thermal modelling of PVT air collector integrated greenhouse drying system has been presented in detail. Average thermal efficiency, electrical efficiency and overall thermal efficiency for PVT air collector are found to be 26.68%, 11.26% and 56.30% respectively at 0.01 kg/s mass flow rate of air. This review paper may be very helpful for researchers and scientists to develop thermal models for different hybrid solar systems. © 2018 Elsevier Ltd

World University root node

Renewable and Sustainable Energy Reviews

PVT air collector integrated greenhouse dryers

International Journal of Agile Systems and Management

Flexible manufacturability analysis applied to the welding process to increase sustainability in engineer-to-order businesses

Intermittency has been observed in the response of aeroelastic systems in the presence of flow fluctuations. This study focuses on developing an understanding of the physical mechanisms that lead to intermittency in such systems. Specifically, the role of time scales of the input flow fluctuations is investigated. Numerical investigations reveal that flow fluctuations with predominantly long time scales in the pre-flutter regime lead to “on–off” type intermittency. On the other hand, rapid fluctuations constituting of small time scales lead to another qualitatively different intermittency, which is referred to in this paper as “burst” type intermittency. It is further shown that the unsteady wake effects play a crucial role in the burst type intermittency. Measures derived from time series analysis of the aeroelastic response are proposed to identify the different dynamical states quantitatively. © 2017 Elsevier Ltd

Journal of Fluids and Structures

Physical mechanism of intermittency route to aeroelastic flutter

Metallic glass nanocomposite thin films were synthesized for an immiscible Ag-Cu alloy system by magnetron sputtering. The structure of the films was unique, consisting of homogeneously dispersed nanocrystallites in an amorphous matrix. The size and volume fraction of the nanocrystallites increased with increasing film thickness resulting in increased elastic modulus and hardness. The high electrical conductivity of the nanocomposite films was examined by a valence-band study, which showed that exchange interaction between Ag and Cu in the nanocomposite structure resulted in enhanced charge carrier concentration. The inverse correlation between electrical conductivity and film thickness was explained by surface and interface scattering of electrons with increasing volume fraction of nanocrystallites. The small temperature dependence of conductivity was attributed to the distorted Fermi surface of the nanocomposite films resulting in a greater contribution from structure scattering, which is temperature-independent. © 2017, The Minerals, Metals &amp; Materials Society.

Metallic Glass Nano-composite Thin Films for High-performance Functional Applications

This paper presents performance evaluation of an energy efficient building named Sodha Bers Complex (SBC) for composite climate of India. SBC is a four story energy efficient building built at Varanasi (U.P.), India. Most of the cooling concepts like orientation, modified Trombe wall, earth shelter, cross ventilation, day lighting, wind tower, wind channel etc. have been incorporated in the design of SBC. The total embodied energy, CO₂ emission, annual energy saving of SBC has been evaluated. Further, energy matrices namely energy payback time (EPBT), energy production factor (EPF) and life cycle conversion efficiency (LCCE) based on an overall annual thermal energy have been evaluated. It has been found that the SBC is most economical from thermal energy point of view due to low grade thermal energy and carbon credit earned. Unit cost has been evaluated for two cases having different interest rate, salvage value and life of SBC building and found to be minimum for 5% of interest rate, 30% salvage value and 300 years of life that is 2.52 [Figure presented]/kWh (0.039 $/kWh) and 2.22 [Figure presented]/kWh (0.034 $/kWh). © 2017

Thermal Science and Engineering Progress

Unit cost analysis for Sodha Bers Complex (SBC): An energy efficient building

In the current study, surface modification of austenitic stainless steel, SS316L, was done using friction stir processing. The strain rates during processing were varied over a wide range by using two different tool rotational speeds of 388 rpm and 1800 rpm. The processing was done at two different conditions of: (i) ambient cooling and (ii) submerging in liquid bath maintained at 0 °C. Friction stir processing resulted in significant grain refinement from 22 μm for the as-received alloy to 0.67 μm for the sample processed at 388 rpm under submerged cooling condition. A relationship between the final recrystallized grain size and Zener-Holloman parameter was developed as Z=72.84/d. Deformation texture for processed specimens showed strong strain rate and temperature dependence. Sample processed at high temperature and low strain-rate showed copper-type texture while low temperature and high strain-rate promoted brass-type texture. Hardness of processed specimens showed an increase while elastic modulus decreased after processing which is explained by texture evolution during processing. Tribological properties of processed specimens were evaluated using reciprocating wear tests and slurry erosion tests. The processed samples showed significant improvement in the wear and erosion resistance and were found to have strong correlation with the flow work given as hardness to elastic modulus ratio. © 2017 Elsevier B.V.

Materials Chemistry and Physics

Structural refinement in austenitic stainless steel by submerged friction stir processing

The ballistic impact performance of a multi-layer material with aluminum foam as the interlayer was investigated numerically in this study. The multi-layer composite material used in this study consists of three functional layers. The ceramic front layer takes the initial impact and converts most of the kinetic energy of the projectile to the energy dissipated in erosion of the projectile material and ceramic. The backing layer which the projectile comes in contact with is a laminated composite fabric which reduces the intensity of the impact by dissipating energy through various forms of damage. The presence of an interlayer in between the front ceramic plate and a composite backing plate has been observed to change the ballistic performance of the composite armor to a great extent numerically. On studying the effect of different inter layers it was observed that the aluminium foam makes the composite layer experience relatively less damage on impact when compared with a specimen without any interlayer. The studies were conducted keeping in mind the weight compensation in each case which led to thickness changes and various distributions of the layers over the cross section. Cause help. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

21st AIAA International Space Planes and Hypersonics Technologies Conference, Hypersonics 2017

High velocity impact on multi-layer materials

Wind tunnel tests on a NACA 0012 airfoil have been carried out to study the transition in aeroelastic response from an initial state characterised by low-amplitude aperiodic fluctuations to aeroelastic flutter when the system exhibits limit cycle oscillations. An analysis of the aeroelastic measurements reveals multi-fractal characteristics in the pre-flutter regime. This has not been studied in the literature. As the flow velocity approaches the flutter velocity from below, a gradual loss in multi-fractality is observed. Measures based on the generalised Hurst exponents are developed and are shown to have the potential to warn against impending aeroelastic flutter. The results of this study could be useful for health monitoring of aeroelastic structures. © 2016 Elsevier Ltd

Journal of Sound and Vibration

Multi-fractality in aeroelastic response as a precursor to flutter

Low flight endurance is a pitfall commonly identified in most modern-day battery powered micro aerial vehicles. This paper presents the design and analysis of a ducted fan micro aerial vehicle(MAV) having a multifunctional, modular structure in order to address the above problem. The ducted fan rotorcraft has been designed particularly to meet the safety and hover efficiency needs for a prolonged indoor surveillance mission. A detailed literature survey on rotorcraft MAVs and multifunctional structural batteries has been reported and discussed. The paper involves detailed conceptual, preliminary and final design stages of a structurally and aerodynamically optimized axial fan that successfully caters to lower power consumption as compared to similar off the shelf propellers available in the market. The MAV incorporates multifunctionality by merging its structural and energy elements into a single subsystem (PAN-based carbon fiber batteries) thereby enhancing flight endurance. © 2017 by the American Helicopter Society International, Inc. All rights reserved.