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Rajani B.N.,National Aerospace Laboratories, Bangalore | Kandasamy A.,National Institute of Technology Karnataka | Majumdar S.,Nitte Meenakshi Institute of Technology
Journal of Applied Fluid Mechanics | Year: 2012

Turbulent flow past circular cylinder at moderate to high Reynolds number has been analysed employing an secondorder time accurate pressure-based finite volume method solving two-dimensional Unsteady Reynolds Averaged Navier Stokes (URANS) equations for incompressible flow, coupled to eddy-viscosity based turbulence models. The major focus of the paper is to test the capabilities and limitations of the present turbulence model-based 2D URANS procedure to predict the phenomenon of Drag Crisis, usually manifested in reliable measurement data, as a sharp drop in the mean drag coefficient around a critical Reynolds number. The computation results are compared to corresponding measurement data for instantaneous aerodynamic coefficients and mean surface pressure and skin friction coefficients. Turbulence model-based URANS computations are in general found to be inadequate for correct prediction of the mean drag coefficients, the Strouhal number and also the coefficients of maximum fluctuating lift over the range of flow Reynolds number varying from 10 4 to 10 7.

Sreenivasappa B.V.,Nitte Meenakshi Institute of Technology
Journal of Electrical Engineering | Year: 2015

The main objective of this paper is to design a smart lighting system with the aim of energy saving and automatic operation. Smart energy saving light switching system can be used in a room where sun light is not uniformly distributed during the day time. In this paper, two light dependent resistor sensors which are used to detect the intensity of light falling on them and one passive infrared sensor used to detect the movement of human body. The switching algorithm is implemented on AT89S52 microcontroller. The hardware of the switching system is designed, fabricated and tested. It has been observed that the light energy switching system gave fairly good result at different locations.

Venkateshappa S.C.,GM Institute of Technology | Puttiah P.K.W.,Nitte Meenakshi Institute of Technology
Advances in Polymer Technology | Year: 2012

In the present work, the mechanical properties of composites obtained by using areca fibers in epoxy matrix have been investigated. The areca fibers extracted from the areca husk are alkali-treated with potassium hydroxide to get better interfacial bonding between fibers and matrix. The test specimens are prepared with different values of weight ratio of fiber to matrix, the fibers being randomly oriented. The test specimens are cured for different periods of time to study the effect of curing time on the mechanical properties. The results of tests such as water absorption, tension, compression, bending, impact, and hardness conducted on the test specimens are herein reported. It is found that the mechanical properties of the composites tested are greatly influenced by (i) alkali treatment of fiber, (ii) weight ratio of fiber-matrix, and (iii) curing time. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 31: 319-330, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20255 Copyright © 2011 Wiley Periodicals, Inc.

Krishnamurthy N.,k-Technology | Murali M.S.,The Academy of Management | Venkataraman B.,Surface Engineering Group | Mukunda P.G.,Nitte Meenakshi Institute of Technology
Wear | Year: 2012

Repeated impact by solid particles causes erosion and degradation of engineering components. In internal combustion engines, during combustion, hot gases are generated in large quantity which causes erosion of cylinder, combustion chamber, exhaust system, etc. In this work, two types of plasma sprayed coating systems were developed on Al-6061 substrate. For each system, a systematic microstructural study was carried out to understand changes occurred after spraying. Mechanical properties like density, adhesion strength and hardness of coatings were determined. A solid particle erosion test was conducted on coating systems according to ASTM G-76-02 and results were correlated with the microstructural and subsequent mechanical property change. It was observed that volume erosion is more at 45° angle of impact and shows that behavior is in between ductile and brittle. This work also discusses the mechanism involved in erosion wear of plasma sprayed coating systems. © 2011 Elsevier B.V.

Shaik H.,Nitte Meenakshi Institute of Technology
Materials Science in Semiconductor Processing | Year: 2015

Mechanical properties of thin films such as residual stress and hardness are of paramount importance from the device fabrication point of view. Intrinsic stress in sputtered films can be tensile or compressive as decided by the number density and the energy of the plasma species striking the growing film. In the presence of hydrogen we analyzed the applicability of idealized stress reversal curve for amorphous silicon thin films deposited by DC, pulsed DC (PDC) and RF sputtering. We are successfully able to correlate the microstructure with the stress reversal and hardness. We observed a stress reversal from compressive to tensile with hydrogen incorporation. It was found that unlike in idealized stress reversal curve case, though the energy of plasma species is less in DC plasma, DC deposited films exhibit more compressive stress, followed by PDC and RF deposited films. A tendency towards tensile stress from compressive stress was observed at ~13, 18 and 23 at%H for DC, PDC and RF deposited films respectively, which is in exact agreement with the vacancy to void transition in the films. Regardless of the sputtering power mode, the hardness of a-Si:H films is found to be maximum at CH~10 at%H. Enhancement in hardness with CH (up to CH~10 at%H) is attributed to increase of Si-H bonds. Beyond CH~10 at%H, hardness starts falling. © 2015 Elsevier Ltd. All rights reserved.

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