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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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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Manu 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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The main purpose of this study is to develop an environmental mitigation behavior model (EMBM) for predicting waste reduction behaviors among young coastal tourists in Bangladesh…
Abstract
Purpose
The main purpose of this study is to develop an environmental mitigation behavior model (EMBM) for predicting waste reduction behaviors among young coastal tourists in Bangladesh by modifying and extending the theory of planned behavior (TPB).
Design/methodology/approach
The research has been administered by applying mixed method (both qualitative and quantitative), where study-1(qualitative) identifies factors, study-2 (quantitative) verifies factors by employing exploratory factor analysis (EFA) approach, and study-3 confirms factors influencing waste reduction behaviors among young coastal tourists by employing confirmatory factor analysis (CFA). Study-2 collects 385 valid responses and analyzes by applying the principal component analysis (PCA) technique with the Varimax rotation method by using SPSS-v25, and Study-3 collects 501 valid responses and analyzes by partial least structural equation modeling (PLS-SEM) technique, using Smart PLS3.3.3.
Findings
The study findings have revealed that waste reduction intention and perceived ecological balance significantly influence waste reduction behaviors among young coastal tourists in Bangladesh. Further, waste reduction intention is significantly predicted by mitigation attitude, resource conservation norms and environmental perceptions. Furthermore, environmental ethics significantly affects mitigation attitudes and resource conservation norms.
Practical implications
The study offers several insightful implications (e.g. incentives, charging fines, environmental awareness-related knowledge-based campaign, etc.) for policymakers and industry operators, which may be a dynamic cost-effective mechanism for reducing waste at coastal tourism destinations in Bangladesh as well as in the world.
Originality/value
This study addresses the need for developing a model that can explain waste reduction behaviors among young coastal tourists in Bangladesh, and thus, the study uniquely postulates the theory of environmental mitigation behavior for predicting waste reduction behaviors by modifying and extending the TPB.
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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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Sudesh Prabhakaran, Vikneswaran Nair and Sridar Ramachandran
The aim of this paper is to examine the various indicators of marine waste management and its adaptability to the tourism industry in Semporna District, Sabah. Marine waste…
Abstract
Purpose
The aim of this paper is to examine the various indicators of marine waste management and its adaptability to the tourism industry in Semporna District, Sabah. Marine waste management was identified as a serious concern in Semporna, specifically the increase in general and hazardous waste and the lack of waste reduction activities. Selected waste management indicators can help to support information‐based decision making in many levels of tourism planning and management.
Design/methodology/approach
The paper is a critical review of previous studies. It provides a theoretical understanding for readers to recognize the indicators used in marine waste management in the context of managing the environment in tourism destinations.
Findings
This paper provides an overview of the environmental indicators widely used in waste management of marine and island destinations and identifies indicators with potential for application in Semporna and islands off the coast of Semporna.
Practical implications
The paper provides vital information to assist the local government select suitable indicators to alleviate marine waste management in Semporna, Sabah.
Originality/value
The paper contributes to a better understanding of marine waste available management indicators in the tourism environment. The use of these dependable measurements should serve as a “report card” for each marine tourism site in the country.
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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.
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.