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Article
Publication date: 3 May 2011

B.K. Prasad

The objectives of this paper are to assess the sliding wear response of a zinc‐based alloy over a range of sliding speeds and pressures in oil‐lubricated condition with respect to…

385

Abstract

Purpose

The objectives of this paper are to assess the sliding wear response of a zinc‐based alloy over a range of sliding speeds and pressures in oil‐lubricated condition with respect to a cast iron, to understand the role of different microconstituents in controlling the observed wear behaviour and to examine various operating material removal mechanisms.

Design/methodology/approach

Sliding wear tests have been carried out using a pin‐on‐disc machine in oil‐lubricated condition at different speeds and pressures. The wear response has been explained in terms of specific nature of various microconstituents of the specimen materials and substantiated through the characteristics of wear surfaces, subsurface regions and debris particles.

Findings

The wear rate increased with the sliding speed while load produced a mixed influence. Further, the friction coefficient and frictional heating were influenced by the test duration, load and speed in a mixed manner. Moreover, the zinc‐based alloy attained lower wear rate but higher friction coefficient than that of the cast iron while frictional heating followed a mixed trend.

Practical implications

The paper further establishes a zinc‐based alloy as a potential substitute material system to a well‐known cast iron in tribological applications and enables further understanding of the wear mechanisms.

Originality/value

The present paper assesses the sliding wear performance of a lighter zinc‐based alloy as an effective potential substitute material system to cast iron in tribological applications. An attempt has also been made to understand the role played by different microconstituents in controlling the wear behavior and substantiate the wear response through the characteristics of wear surfaces, subsurface regions and debris.

Details

Industrial Lubrication and Tribology, vol. 63 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 May 2009

B.K. Prasad

The purpose of this paper is to understand the sliding wear response of a cast iron as influenced by applied load and changing concentration of solid lubricant (graphite…

843

Abstract

Purpose

The purpose of this paper is to understand the sliding wear response of a cast iron as influenced by applied load and changing concentration of solid lubricant (graphite) particles in oil lubricant, and operating material removal mechanisms in different sets of experimental conditions.

Design/methodology/approach

The sliding wear response of a grey cast iron has been examined as a function of test environment and load. Properties evaluated were wear rate, friction coefficient and frictional heating. The wear behaviour of the samples has been substantiated through the characteristics of their wear surfaces, subsurface regions and debris particles.

Findings

The wear rate and frictional heating increased with load while friction coefficient was affected in an opposite manner. The presence of oil lubricant led to a substantial improvement in wear response (in terms of decreasing wear rate, friction coefficient and frictional heating) while the presence of graphite particles in the oil lubricant proved to be still better. A critical content of graphite in the oil lubricant becomes most effective towards improving the wear response of the samples. Formation of dark patches on the wear surface, substantial subsurface deformation and fine debris led to improved wear response.

Research limitations/implications

The study enables one to understand the wear behaviour of a cast iron as influenced by the changing concentration of solid lubricant (graphite) particles in the oil lubricant. It also enables one to understand the operating material removal mechanisms responsible for the observed wear characteristics of the samples under varying test conditions. The investigation helps one to see that only a critical concentration of the solid lubricant particles in oil can lead to the best wear performance of materials.

Originality/value

From a practical standpoint, the observations made here gain importance from the fact that solid lubricants are added frequently in oil in engineering applications but it becomes imperative to understand that only a critical concentration can lead to the best wear behaviour of materials.

Details

Industrial Lubrication and Tribology, vol. 61 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 5 August 2014

B.K. Prasad

The purpose of the paper is to assess the influence of the volume fraction solid lubricants like talc lead and graphite in oil separately and in combination towards controlling…

137

Abstract

Purpose

The purpose of the paper is to assess the influence of the volume fraction solid lubricants like talc lead and graphite in oil separately and in combination towards controlling the sliding wear behaviour of a grey cast iron and understand the factors controlling the response of the material in a given set of experimental conditions.

Design/methodology/approach

The composition of the lubricating medium (oil) has been changed by dispersing 5 per cent graphite, talc and lead particles separately and in combination. Sliding wear tests were conducted on grey cast iron samples over a range of applied pressures. Parameters determined were wear rate and frictional heating. The wear behaviour of the samples was further substantiated through the features of wear surfaces, subsurface regions and debris particles. Material removal mechanisms and factors responsible for a specific response of the samples have also been analysed.

Findings

The wear rate increased with increasing applied pressure. Addition of graphite and lead to the oil separately or in combination brought about a reduction in the wear rate of the samples; talc and talc + lead produced a reverse trend. Temperature near the specimen surface increased with test duration and applied pressure. The test environment influenced the frictional heating in a manner similar to that of the wear rate. Adhesion and abrasion were observed to be the operating material removal mechanisms. Smearing of the solid lubricating phase and delamination resulting from cracking tendency also controlled the wear response.

Research limitations/implications

Oil is a very popular lubricant used in engineering applications involving friction and wear. Solid lubricants are used along with the oil. The nature, characteristics and content of the solid lubricants very much control the performance. Limited information is available pertaining to assessing the influence of the type and fraction of solid lubricants in the oil towards controlling the wear behaviour of cast irons (popularly known tribomaterials). The present study enables to understand the effectiveness of talc, lead and graphite in oil towards governing the wear characteristics of cast iron and analyse wear mechanisms and controlling parameters.

Practical implications

Graphite and talc are available in nature in abundance. Graphite is a popularly known solid lubricant, while talc is less explored. Lead is also well-known as a solid lubricant but poses health hazard in practice due to its toxic nature. The present study explores the lubricating capability of talc when mixed with oil separately or in combination with lead and graphite towards controlling the wear response of a grey cast iron. It enables to understand the factors responsible for the specific response of talc.

Social implications

Assessment of the lubricating potential of talc as a possible substitute to lead is important in view of the toxic nature of the latter. If successful, the exercise could enable to replace lead with talc.

Originality/value

The present manuscript is an original piece of the author's research work.

Details

Industrial Lubrication and Tribology, vol. 66 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 8 October 2019

Manjunatha Gudekote, Rajashekhar Choudhari, Hanumesh Vaidya, Prasad K.V. and Viharika J.U.

The purpose of this paper is to emphasize the peristaltic mechanism of power-law fluid in an elastic porous tube under the influence of slip and convective conditions. The effects…

42

Abstract

Purpose

The purpose of this paper is to emphasize the peristaltic mechanism of power-law fluid in an elastic porous tube under the influence of slip and convective conditions. The effects of different waveforms on the peristaltic mechanism are taken into account.

Design/methodology/approach

The governing equations are rendered dimensionless using the suitable similarity transformations. The analytical solutions are obtained by using the long wavelength and small Reynold’s number approximations. The expressions for velocity, flow rate, temperature and streamlines are obtained and analyzed graphically. Furthermore, an application to flow through an artery is determined by using a tensile expression given by Rubinow and Keller.

Findings

The principal findings from the present model are as follows. The axial velocity increases with an expansion in the estimation of velocity slip parameter and fluid behavior index, and it diminishes for a larger value of the porous parameter. The magnitude of temperature diminishes with an expansion in the Biot number. The flux is maximum for trapezoidal wave and minimum for the triangular wave when compared with other considered waveforms. The flow rate in an elastic tube increases with an expansion in the porous parameter, and it diminishes with an increment in the slip parameter. The volume of tapered bolus enhances with increasing values of the porous parameter.

Originality/value

The current study finds the application in designing the heart-lung machine and dialysis machine. The investigation further gives a superior comprehension of the peristaltic system associated with the gastrointestinal tract and the stream of blood in small or microvessels.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 2
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 20 October 2023

Ajay Kumar Jaiswal and Pallab Sinha Mahapatra

Maintaining the turbine blade’s temperature within the safety limit is challenging in high-pressure turbines. This paper aims to numerically present the conjugate heat transfer…

124

Abstract

Purpose

Maintaining the turbine blade’s temperature within the safety limit is challenging in high-pressure turbines. This paper aims to numerically present the conjugate heat transfer analysis of a novel approach to mini-channel embedded film-cooled flat plate.

Design/methodology/approach

Numerical simulations were performed at a steady state using SST kω turbulence model. Impingement and film cooling are classical approaches generally adopted for turbine blade analysis. The existing film cooling techniques were compared with the proposed design, where a mini-channel was constructed inside the solid plate. The impact of the blowing ratio (M), Biot number (Bi) and temperature ratio (TR) on overall cooling performance was also studied.

Findings

Overall cooling effectiveness was always shown to be higher for mini-channel embedded film-cooled plates. The effectiveness increases with increasing the blowing ratio from M = 0.3 to 0.7, then decreases with increasing blowing ratio (M = 1 and 1.4) due to lift-off conditions. The mini-channel embedded plate resulted in an approximately 21% increase in area-weighted average overall effectiveness at a blowing ratio of 0.7 and Bi = 1.605. The lower uniform temperature was also found for all blowing ratios at a low Biot number, where conduction heat transfer significantly impacts total cooling effectiveness.

Originality/value

To the best of the authors’ knowledge, this study presents a novel approach to improve the cooling performances of a film-cooled flat plate with better cooling uniformity by using embedded mini-channels. Despite the widespread application of microchannels and mini-channels in thermal and fluid flow analysis, the application of mini-channels for blade cooling is not explored in detail.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 27 August 2024

RamReddy Chetteti, Sweta   and Pranitha Janapatla

This study aims to enhance heat transfer efficiency while minimizing friction factor and entropy generation in the flow of Nickel zinc ferrite (NiZnFe2O4) nanoparticles suspended…

36

Abstract

Purpose

This study aims to enhance heat transfer efficiency while minimizing friction factor and entropy generation in the flow of Nickel zinc ferrite (NiZnFe2O4) nanoparticles suspended in multigrade 20W-40 motor oil (as specified by the Society of Automotive Engineers). The investigation focuses on the effects of the melting process, nonspherical particle shapes, thermal dispersion and viscous dissipation on the nanofluid flow.

Design/methodology/approach

The fundamental governing equations are transformed into a set of similarity equations using Lie group transformations. The resulting set of equations is numerically solved using the spectral local linearization method. Additionally, sensitivity analysis using response surface methodology (RSM) is conducted to evaluate the influence of key parameters on response function.

Findings

Higher dispersion reduces entropy production. Needle-shaped particles significantly enhance heat transfer by 27.65% with melting and reduce entropy generation by 45.32%. Increasing the Darcy number results in a reduction of friction by 16.06%, lower entropy by 31.72% and an increase in heat transfer by 17.26%. The Nusselt number is highly sensitive to thermal dispersion across melting and varying volume fraction parameters.

Originality/value

This study addresses a significant research gap by exploring the combined effects of melting, particle shapes and thermal dispersion on nanofluid flow, which has not been thoroughly investigated before. The focus on practical applications such as fuel cells, material processing, biomedicine and various cooling systems underscores its relevance to sectors such as nuclear reactors, tumor treatments and manufacturing. The incorporation of RSM for friction factor analysis introduces a unique dimension to the research, offering novel insights into optimizing nanofluid performance under diverse conditions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 10
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 28 October 2014

Amit K. Chauhan, B.V.S.S.S. Prasad and B.S.V. Patnaik

The purpose of this paper is to investigate the effect of narrow gap on the fluid flow and heat transfer through an eccentric annular region is numerically. Flow through an…

421

Abstract

Purpose

The purpose of this paper is to investigate the effect of narrow gap on the fluid flow and heat transfer through an eccentric annular region is numerically. Flow through an eccentric annular geometry is a model problem of practical interest.

Design/methodology/approach

The approach involves standard finite volume-based SIMPLE scheme. The numerical simulations cover the practically relevant Reynolds number range of 104-106.

Findings

In the narrow gap region, temperature shoot up was observed due to flow maldistribution with an attendant reduction in the heat removal from the wall surfaces. CFD analysis is presented with the aid of, streamlines, isotherms, axial velocity contours, etc. The engineering parameters of interest such as, Nusselt number, wall shear stress, etc., is presented to study the effect of eccentricity and radius ratio.

Research limitations/implications

The present investigation is a simplified model for the rod bundle heat transfer studies. However, the detailed study of sectorial mass flux distribution is a useful precursor to the thermal hydraulics of rod bundles.

Practical implications

For nuclear reactor fuel rods, the effect of eccentricity is going to be detrimental and might lead to the condition of critical heat flux. A thorough sub-channel analysis is very useful.

Social implications

Nuclear safety standards require answers to a wide a range of what-if type hypothetical scenarios to enable preparedness. This study is a highly simplified model and a first step in that direction.

Originality/value

The narrow gap region has been systematically investigated for the first time. A detailed sectorial analysis reveals that, flow maldistribution and the attendant temperature shoot up in the narrow gap region is detrimental to the safe operation.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 8
Type: Research Article
ISSN: 0961-5539

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Book part
Publication date: 28 September 2023

Akansha Mer and Amarpreet Singh Virdi

The study aims to propose a conceptual Bhartiya (Indian) model of workplace spirituality (WPS) in non-profit organisations (NPOs) in the context of burnout and resilience by…

Abstract

The study aims to propose a conceptual Bhartiya (Indian) model of workplace spirituality (WPS) in non-profit organisations (NPOs) in the context of burnout and resilience by synthesising the concepts of the east and the west. The researchers have kept an open approach by exploring various dimensions of WPS by reviewing the extant literature of both the east and the west. The researchers delved into Bhartiya (Indian) scriptures to identify the concepts that have similarity with the dimensions of WPS so that it may further assist in facilitating those dimensions in NPOs. Furthermore, to propose a conceptual Bhartiya model for NPOs, the researchers synthesised the literature pool of Bhartiya studies on WPS. They examined how WPS decreases burnout and leads to resilience. The study’s findings reveal that concepts from Bhartiya scriptures such as Karm Yog (Nishkam Karm, self-abnegation, swadharm), parasparam bhavayantaha, loksangrah, daivi sampat and kritagyata are instrumental in facilitating the constructs of WPS. Meaningful work is facilitated through karm yog; sense of community is facilitated through parasparam bhavayantaha and loksangrah; and alignment with organisational values is facilitated through daivi sampat and kritagyata. The findings further suggest that WPS is an antidote to burnout and an enabler of resilience.

Details

Digital Transformation, Strategic Resilience, Cyber Security and Risk Management
Type: Book
ISBN: 978-1-80455-262-9

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Article
Publication date: 8 October 2020

Yijiang Peng, Zhenghao Wu, Liping Ying and Desi Yang

This paper aims to propose the five-phase sphere equivalent model of recycled concrete, which can be used to deduce the theoretical formulas for the Poisson’s ratio and effective…

177

Abstract

Purpose

This paper aims to propose the five-phase sphere equivalent model of recycled concrete, which can be used to deduce the theoretical formulas for the Poisson’s ratio and effective elastic modulus.

Design/methodology/approach

At a mesoscopic level, the equivalent model converts the interfacial layer, which consists of the new interfacial transition zone (ITZ), the old mortar and the old (ITZ), into a uniform equivalent medium. This paper deduces a strength expression for the interfacial transition zone at the microscopic level using the equivalent model and elastic theory. In addition, a new finite element method called the base force element method was used in this research.

Findings

Through numerical simulation, it was found that the mechanical property results from the five-phase sphere equivalent model were in good agreement with those of the random aggregate model. Furthermore, the proposed model agree on quite well with the available experimental data.

Originality/value

The equivalent model can eliminate the influence of the interfacial layer on the macroscopic mechanical properties, thereby improving the calculation accuracy and computational efficiency. The proposed model can also provide a suitable model for multi-scale calculations.

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Article
Publication date: 11 September 2007

Paresh Kumar Narayan, Seema Narayan, Biman Chand Prasad and Arti Prasad

This paper aims to examine the export‐led growth hypothesis for Fiji and Papua New Guinea (PNG).

2752

Abstract

Purpose

This paper aims to examine the export‐led growth hypothesis for Fiji and Papua New Guinea (PNG).

Design/methodology/approach

The paper investigates the export‐led growth hypothesis for Fiji and PNG who have been facing dismal economic growth performances over the last couple of decades.

Findings

Findings of the study suggest that for Fiji there is evidence of export‐led growth in the long‐run, while for PNG there is evidence of export‐led growth in the short‐run.

Originality/value

The findings of this paper have important messages for policy makers given that export sectors in both countries investigated are underdeveloped due mainly to a sustained period of political instability.

Details

Journal of Economic Studies, vol. 34 no. 4
Type: Research Article
ISSN: 0144-3585

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