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1 – 10 of 22Manu V. Thottackkad, P.K. Rajendrakumar and K. Prabhakaran Nair
– This manuscript aims to deal with the tribological property variations of engine oil (SAE15W40) by the addition of copper oxide (CuO) nanoparticles on weight percentage basis.
Abstract
Purpose
This manuscript aims to deal with the tribological property variations of engine oil (SAE15W40) by the addition of copper oxide (CuO) nanoparticles on weight percentage basis.
Design/methodology/approach
Experimental studies on the influence of CuO nanoparticles utilised as an additive in lubricating oil (SAE15W40) under boundary lubrication conditions have been carried out using a pin-on-disc machine in accordance with ASTM G-99 standard. The variation of viscosity, coefficient of friction, wear and settling of nanoparticles has been studied as a function of particle concentration in the lubricant.
Findings
Results show that the frictional force and specific wear rate decrease with an increase in concentration of nanoparticles comes to a minimum at a specific concentration and then increases, showing the presence of an optimum concentration. With the increase in concentration of nanoparticles, the kinematic and dynamic viscosities, and the flash and fire points are found to increase.
Originality/value
The use of CuO nanoparticles as additives to a moderate level is a very efficient means of improving the tribological properties of lubricating oils.
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M. Nekoeimehr, A.D. Rahmatabadi and R. Rashidi
The purpose of this paper is to analyse the static performance characteristics of lobe journal bearings lubricated with a micropolar fluid, considering effect of non‐circularity…
Abstract
Purpose
The purpose of this paper is to analyse the static performance characteristics of lobe journal bearings lubricated with a micropolar fluid, considering effect of non‐circularity. Number of lobes and their preload value are the non‐circularity parameters considered in the present study. The bearings undertaken for the investigation are two, three and four‐lobe symmetric journal bearings with finite width.
Design/methodology/approach
For this purpose, modified form of Reynolds equation is derived, based on Eringen's micropolar fluid theory and it is solved numerically using finite element method (FEM). The effect of the non‐circularity parameters of bearings on the steady‐state performance characteristics such as load carrying capacity, attitude angle, coefficient of friction and side leakage flow are presented and discussed.
Findings
The results show that the number of lobes and their preload value can influence the performance of lobe bearings. It is seen that, in order to provide certain improvement over simple cylindrical bearings, the non‐circularity parameters of lobe bearings must be chosen correctly. There is no single optimum profile for multi‐lobe bearing application.
Originality/value
Lobe bearings, compared with simple circular bearings, offer several geometric parameters to designers. These parameters must be chosen correctly, so that the requirements of a specific application can be fulfilled.
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Boualem Chetti and Wael Ahmed Crosby
The purpose of this paper is to present the effect of the preload on the static characteristics of three-lobe bearings lubricated with a fluid blended with high polymer additives…
Abstract
Purpose
The purpose of this paper is to present the effect of the preload on the static characteristics of three-lobe bearings lubricated with a fluid blended with high polymer additives modeled as a couple stress fluid.
Design/methodology/approach
Based on the micro-continuum theory, the modified Reynolds equation for couple stress fluids is solved using a finite difference method to obtain the distribution of the pressure, the load-carrying capacity, the attitude angle, the friction coefficient and the side leakage for various values of the couple stress parameter and the preload factor.
Findings
The results show that the presence of a couple stress in the lubricants improves the static characteristics of this type of bearing compared to those lubricated with Newtonian fluids for any value of the preload factor. Thus, it is found that the preload significantly affects the performance of the three-lobe journal bearing lubricated with a couple stress fluid or a Newtonian fluid. Moreover, the investigation showed that increasing the preload factor exhibits an increase in the load carrying capacity and the attitude angle, but it decreases the friction coefficient and the side leakage especially at a lower preload factor. Furthermore, using a couple stress fluid and a higher preload factor led to a significant rise in the load carrying capacity and a significant reduction in the friction coefficient.
Practical implications
This study helped improve the performance characteristics of the three-lobe journal bearing.
Originality/value
The presence of couple stress in the lubricants improves the static characteristics of this type of bearing compared to those lubricated with Newtonian fluids for any value of the preload factor. The usage of the couple stress fluid and the higher preload factor led to a significant rise in the load carrying capacity and a significant reduction in the friction coefficient.
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Sreedhar Babu Kalakada, Prabhakaran Nair Nair Kumarapillai and Rajendra Kumar P K
The purpose of this work is to investigate the static performance characteristics of thermohydrodynamic journal bearing operating under nanolubricants (lubricants containing per…
Abstract
Purpose
The purpose of this work is to investigate the static performance characteristics of thermohydrodynamic journal bearing operating under nanolubricants (lubricants containing per cent weight concentration of nanoparticles).
Design/methodology/approach
Addition of nanoparticles in the lubricant increases lubricant viscosity. To study the effect of this variation on journal bearing, analytical models are developed for the relationship between viscosity, 0-0.5 per cent weight concentration of nanoparticles and temperature range of 300-900°C. To obtain pressure and temperature distribution, modified Reynolds and energy equations are solved by using the finite element method. The viscosity field (varies with temperature and per cent weight concentration of nanoparticles) is updated in these two equations by using the developed analytical model. The steady-state performance characteristics are computed for various values of eccentricity ratios for non-thermoviscous (viscosity of lubricant varies with per cent weight concentration of nanoparticles) and thermoviscous (viscosity of lubricant varies with per cent weight concentration of nanoparticles and temperature) cases. The lubricant and the nanoparticles used for the present work are SAE15W40, copper oxide (CuO), cerium oxide (CeO2) and aluminum oxide (Al2O3).
Findings
The pressure and temperature distribution across the lubricant film in the clearance space of journal bearing and static performance characteristics are calculated.
Originality/value
The computed results show that addition of nanoparticles in the lubricant influences the performance characteristics considerable in thermoviscous case than non-thermoviscous case.
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Sudesh Prabhakaran, Vikneswaran Nair and Sridar Ramachandran
Waste in the marine environment has become a serious task to be managed. Uncontrolled dumping creates large amounts of methane gas contributing to greenhouse gas emissions. This…
Abstract
Purpose
Waste in the marine environment has become a serious task to be managed. Uncontrolled dumping creates large amounts of methane gas contributing to greenhouse gas emissions. This conceptual paper focuses on the role of community in waste management activities to reduce carbon emissions in the marine environment. Hence, this paper aims to examine using literature, the various roles of community, types of marine waste and its impact on carbon emissions and climate change.
Design/methodology/approach
The paper is based on evaluation and criticism from previous studies and provides a hypothetical understanding of the human contribution to climate change, and its impacts which will increasingly affect climate change and sustainable tourism.
Findings
The results from this study can be used as a guide for policy makers to help improve community participation and public engagement in efforts to reduce the levels of waste in the marine environment. This is especially critical in rural tourism destinations where the impact of uncontrolled marine waste has serious consequences for the tourism industry.
Originality/value
The paper contributes to a better understanding of the role of community in mitigating waste to attain a higher quality of tourism experience and environmental benefits from emission level reductions.
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Saijal Kizhakke Kodakkattu, Prabhakaran Nair and Joy M.L.
The purpose of this study is to obtain optimum locations, peak deflection and chord of the twin trailing-edge flaps and optimum torsional stiffness of the helicopter rotor blade…
Abstract
Purpose
The purpose of this study is to obtain optimum locations, peak deflection and chord of the twin trailing-edge flaps and optimum torsional stiffness of the helicopter rotor blade to minimize the vibration in the rotor hub with minimum requirement of flap control power.
Design/methodology/approach
Kriging metamodel with three-level five variable orthogonal array-based data points is used to decouple the optimization problem and actual aeroelastic analysis.
Findings
Some very good design solutions are obtained using this model. The best design point in minimizing vibration gives about 81 per cent reduction in the hub vibration with a penalization of increased flap power requirement, at normal cruise speed of rotor-craft flight.
Practical implications
One of the major challenges in the helicopters is the high vibration level in comparison with fixed wing aircraft. The reduction in vibration level in the helicopter improves passenger and crew comfort and reduces maintenance cost.
Originality/value
This paper presents design optimization of the helicopter rotor blade combining five design variables, such as the locations of twin trailing-edge flaps, peak deflection and flap chord and torsional stiffness of the rotor. Also, this study uses kriging metamodel to decouple the complex aeroelastic analysis and optimization problem.
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Umberto Visconti, WonJong Eun, JiSoo Sim, SangWoo Lee and SangJoon Shin
The purpose of this paper is to present the design, analysis and experiments of the active trailing-edge flap (Seoul National University Flap, SNUF) for vibration reduction in the…
Abstract
Purpose
The purpose of this paper is to present the design, analysis and experiments of the active trailing-edge flap (Seoul National University Flap, SNUF) for vibration reduction in the helicopter rotor prior to the small-scale blades planned to test in a whirl tower.
Design/methodology/approach
The predictions of the hinge moment in both steady and unsteady flows were obtained through computational fluid dynamics calculations. When compared with the results originated from analytical formulations, the proposed method showed improved prediction capabilities. To validate the deflection of the flap under the centrifugal load by rotating, static analysis was conducted using both contact and rotating condition of MSC NASTRAN. The corresponding experiment also was performed using the vertical frame for simulating the effect of the centrifugal force.
Findings
The hinge moment of the flap is predicted through unsteady analysis in the actuation frequency of 3/rev. The material of the guide in the flap mechanism was selected through static analysis under both contact and rotating condition. Finally, reduction of the deflection occurred because of the load in the axial direction of the hinge like the centrifugal load.
Practical implications
The important aspects, such as design, analysis, and experiments for the active trailing-edge flap were shown.
Originality/value
This paper showed the relationship of the displacement, block force and voltage of the piezo-actuator, combined with the hinge moment predicted. The methodology and the experiment were presented for simulating the centrifugal force acting on the flap.
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Deepa Jain, Manoj Kumar Dash and K. S. Thakur
In this chapter, to explore the past and understand the present scenario in financial market, a comprehensive literature review (LR) is performed, in which 809 articles from the…
Abstract
In this chapter, to explore the past and understand the present scenario in financial market, a comprehensive literature review (LR) is performed, in which 809 articles from the database of Scopus for the last 10 years are extracted and analyzed using VOSviewer software for bibliometric analysis. Citation analysis of the popular identified factors is highlighted that will help the future researchers to focus on the identified popular factors for research in the financial market. The chapter also presents a conceptual model of financial market, to uncover the future of financial markets.
Nurul Farhanah Azman, Syahrullail Samion, Muhammad Amirrul Amin Moen, Mohd Kameil Abdul Hamid and Mohamad Nor Musa
The purpose of this paper is to investigate the anti-wear (AW) and extreme pressure (EP) performances of CuO and graphite nanoparticles as a palm oil additive.
Abstract
Purpose
The purpose of this paper is to investigate the anti-wear (AW) and extreme pressure (EP) performances of CuO and graphite nanoparticles as a palm oil additive.
Design/methodology/approach
In this study, the AW and EP performances of CuO and graphite nanoparticles as additives in palm oil were evaluated using four ball tribotester in accordance to ASTM D4172 and ASTM D2783, respectively. The wear worn surfaces of the steel balls were analysed using high resolution microscope.
Findings
The results obtained demonstrate that CuO and graphite nanoparticles improved the AW and EP performances of the palm oil up to 2.77 and 12 per cent, respectively. The graphite nanoparticles provide better AW and EP performance than that of CuO nanoparticles.
Originality/value
This demonstrates the potential of CuO and graphite nanoparticles for improving AW and EP performances of palm oil base lubricant. Different morphology of nanoparticles will affect the AW and EP performances of nanolubricants.
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Rehan Zahid, Masjuki Hj. Hassan, Abdullah Alabdulkarem, Mahendra Varman, Md. Abul Kalam, Riaz Ahmad Mufti, Nurin Wahidah Mohd Zulkifli, Mubashir Gulzar, Muhammad Usman Bhutta, Mian Ashfaq Ali, Usman Abdullah and Robiah H. Yunus
There is a continuous drive in automotive sector to shift from conventional lubricants to environmental friendly ones without adversely affecting critical tribological performance…
Abstract
Purpose
There is a continuous drive in automotive sector to shift from conventional lubricants to environmental friendly ones without adversely affecting critical tribological performance parameters. Because of their favorable tribological properties, chemically modified vegetable oils such as palm trimethylolpropane ester (TMP) are one of the potential candidates for the said role. To prove the suitability of TMP for applications involving boundary-lubrication regime such as cam/tappet interface of direct acting valve train system, a logical step forward is to investigate their compatibility with conventional lubricant additives.
Design/methodology/approach
In this study, extreme pressure and tribological characteristics of TMP, formulated with glycerol mono-oleate (GMO), molybdenum dithiocarbamate (MoDTC) and zinc dialkyldithiophosphate (ZDDP), has been investigated using four-ball wear tester and valve train test rig. For comparison, additive-free and formulated versions of polyalphaolefin (PAO) were used as reference. Moreover, various surface characterization techniques were deployed to investigate mechanisms responsible for a particular tribological behavior.
Findings
In additive-free form, TMP demonstrated better extreme pressure characteristics compared to PAO and lubricant additives which are actually optimized for conventional base-oils such as PAO, are also proved to be compatible with TMP to some extent, especially ZDDP. During cylinder head tests, additive-free TMP proved to be more effective compared to PAO in reducing friction of cam/tappet interface, but opposite behavior was seen when formulated lubricants were used. Therefore, there is a need to synthesize specialized friction modifiers, anti-wear and extreme pressure additives for TMP before using it as engine lubricant base-oil.
Originality/value
In this study, additive-free and formulated versions of bio-lubricant are tested for cam/tappet interface of direct acting valve train system of commercial passenger car diesel engine for the very test time. Another important aspect of this research was comparison of important tribological performance parameters (friction torque, wear, rotational speed of tappet) of TMP-based lubricants with conventional lubricant base oil, that is, PAO and its formulated version.
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