Gourav Jamwal, Sanjay Sharma and R.K. Awasthi
This paper aims to evaluate the various dynamic performance parameters of hydrodynamic journal bearings. For this, the bearing’s inner surface is textured with chevron-shaped…
Abstract
Purpose
This paper aims to evaluate the various dynamic performance parameters of hydrodynamic journal bearings. For this, the bearing’s inner surface is textured with chevron-shaped textures with different texture depths and number of textures in different regions/locations.
Design/methodology/approach
In the present study, the effect of chevron-shaped texture having different values of texture depths, locations and number of textures has been numerically simulated. The dynamic performance characteristics have been calculated by solving the fluid flow governing Reynolds equation using the finite element method, assuming iso-viscous and Newtonian fluid.
Findings
The obtained results indicate that the bearing stability can be improved with the help of surface texture. Among all the investigated texture locations, the maximum increase in stability threshold speed is observed for fully textured distribution. Moreover, for the chevron-shaped texture considered in the present study, the optimum values of texture depth and number of textures have also been determined for maximum bearing stability.
Practical implications
While designing, designers should focus on those optimum values of texture depth, texture location and number of textures which lead to maximum enhancement in bearing stability.
Originality/value
This study is useful in the appropriate selection of chevron-shaped texture parameters on bearing surface for the maximum bearing stability.
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Sanjay Sharma, Gourav Jamwal and R.K. Awasthi
The purpose of this paper is to provide the various steady state parameters of hydrodynamic journal bearings have been determined to get maximum performance enhancement ratio. For…
Abstract
Purpose
The purpose of this paper is to provide the various steady state parameters of hydrodynamic journal bearings have been determined to get maximum performance enhancement ratio. For this, the bearings inner surface is textured with triangular shape with different texture depths and a number of textures in pressure increasing region. The textured region acts as a lubricant reservoir, which provides additional film-thickness and reduce friction. Therefore, enhance the overall performance of bearing.
Design/methodology/approach
In the present study, the effect of triangular shaped texture on the static performance characteristics of a hydrodynamic journal bearing has been studied. Different values of texture depths and a number of textures have been numerically simulated in pressure developing region. The static performance characteristics have been calculated by solving the fluid flow governing Reynolds equation using the finite element method, assuming iso-viscous Newtonian fluid. The performance enhancement ratio, which is the ratio of load carrying capacity (LCC) to the coefficient of friction (COF) has been calculated from results to finalized optimum design parameters.
Findings
The paper provides numerically obtained results indicate that surface texturing can improve bearing performance if the textured region is placed in the pressure increasing region. Moreover, surface texturing is the most effective at bearing performance enhancement when the bearing operates at lower eccentricity ratios and texture depth. The performance enhancement ratio, which is the ratio of LCC to the COF is found to be a maximum value of 2.198 at texture depth of 1.5, eccentricity ratio of 0.2 and the textured region located in the increasing pressure region.
Research limitations/implications
The present study is based on a numerical based research approach, which has its limitations. So, researchers are encouraged to investigate the same work experimentally.
Practical implications
The paper includes implications to be beneficial for designers for designing better hydrodynamic journal bearings.
Originality/value
For the triangular shaped texture, considered in the present study, the optimum values of texture depth and texture distribution region have also been determined. While designing, designers should focus on those values of texture depth, texture region and a number of textures, which give the maximum value of performance enhancement ratio, which represents maximum LCC at the lowest value of the COF.
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Deepak Byotra and Sanjay Sharma
This study aims to understand how the texture shape, number of textures and addition of nanoparticle additives in lubricants impact the dynamic characteristics of journal bearing…
Abstract
Purpose
This study aims to understand how the texture shape, number of textures and addition of nanoparticle additives in lubricants impact the dynamic characteristics of journal bearing by comparing six different texture shapes like triangle, chevron, arc, circle, rectangle and elliptical applied in pressure-increasing region under various geometrical and operating conditions.
Design/methodology/approach
The finite element method approach has been employed to solve governing Reynold’s equation, assuming iso-viscous Newtonian fluid, for computation of performance parameters like stiffness and damping coefficient, threshold speed, etc. By using a regression model, the impact of adding nanoparticles Al2O3 and CuO to the base lubricant on viscosity variation is calculated for selected temperature ranges and weight fractions of nanoparticles.
Findings
The arc-shaped texture with an area density of 28.27%, eccentricity ratio of 0.2 and texture depth of 0.6 exhibited 35.22% higher direct stiffness and 41.4% higher damping coefficient compared to the lowest value in the circle-shaped texture. Increasing the number of arc-shaped textures on the bearing surface with low area density led to declining stiffness and damping parameters. However, with nanoparticle additives, the arc-shaped texture further showed 10.75% and 8.11% improvement in stiffness and 9.99% and 4.87% enhancement in damping coefficient for Al2O3 and CuO, respectively, at 90 °C temperature and 0.5% weight fraction.
Originality/value
By understanding the influence of texture shapes on the dynamic characteristics, engineers can design bearings that exhibit improved stability and enhance overall performance.
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Current paper is an overview of qualitative research. It starts with discussing meaning of research and links it with a framework of experiential learning. Complexity of…
Abstract
Current paper is an overview of qualitative research. It starts with discussing meaning of research and links it with a framework of experiential learning. Complexity of socio-political environment can be captured with methodologies appropriate to capture dynamism and intricacy of human life. Qualitative research is a process of capturing lived-in experiences of individuals, groups, and society. It is an umbrella concept which involves variety of methods of data collection such as interviews, observations, focused group discussions, projective tools, drawings, narratives, biographies, videos, and anything which helps to understand world of participants. Researcher is an instrument of data collection and plays a crucial role in collecting data. Main steps and key characteristics of qualitative research are covered in this paper. Reader would develop appreciation for methodiness in qualitative research. Quality of qualitative research is explained referring to aspects related to rigor, worthiness of topic in interpretivist research. This paper presents challenges of qualitative research in terms of thinking of qualitative research, doing of qualitative research, and trustworthiness.
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Deepak Byotra and Sanjay Sharma
This study aims to find the dynamic performance parameters of the journal bearing with micro geometries patterning the arc (crescent) shape textures provided in three specific…
Abstract
Purpose
This study aims to find the dynamic performance parameters of the journal bearing with micro geometries patterning the arc (crescent) shape textures provided in three specific regions of the journal bearing: the full, the second half and the increasing pressure region. The dynamic behavior of textured journal bearings has been analyzed by computing dynamic parameters and linear and non-linear trajectories.
Design/methodology/approach
The lubricant flows between the bearing and journal surface are governed by Reynold’s equation, which has been solved by finite the element method. The dynamic performance parameters such as stiffness, damping, threshold speed, critical mass and whirl frequency ratio are examined under various operating conditions by considering various ranges of eccentricity ratios and texture depths. Linear and non-linear equations of motion have been solved with Ranga–Kutta method to get journal motion trajectories. Also, the impact of adding aluminum oxide and copper oxide nanoparticles to the base lubricant in combination with arc-shaped textures is analyzed to further see any enhancement in the performance parameters.
Findings
The findings demonstrated that direct stiffness and damping parameters increased to their maximum level with six textures in the pressure-increasing region when compared with the untextured surface. Also, nanoparticle additives showed improvements above the highest value attained with no inclusion of additives in the same region or quantity of textures.
Originality/value
Engineers may design bearings with improved stability and overall performance if they understand how texture form impacts dynamic properties.
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Sumita Mishra and Rabi N. Subudhi
The introductory paper begins with the issue about the relevance of research in management. It emphasizes the need for scholars to adopt methodologies best suited to the research…
Abstract
The introductory paper begins with the issue about the relevance of research in management. It emphasizes the need for scholars to adopt methodologies best suited to the research problem of their choice. This paper contains sections on the nature of management research, dominant research paradigms, the methodological domain, quantitative versus qualitative research, and triangulation in using multiple methodologies. The paper provides a background to the purpose of the book and summarizes in brief the purpose of each the subsequent papers.
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Saurabh Kumar Yadav, Arvind Kumar Rajput, Nathi Ram and Satish Chandra Sharma
This study aims to analyze the dynamic performance of aerostatic thrust bearing for different geometries of recess. Different geometries of recess of equal recess area, i.e…
Abstract
Purpose
This study aims to analyze the dynamic performance of aerostatic thrust bearing for different geometries of recess. Different geometries of recess of equal recess area, i.e. circular, elliptical, rectangular and annular, have been considered in analysis. The work also analyzes the influence of tilt angle on the performance of thrust bearing. To compute the unknown pressure field, the Reynolds equation governing the flow of compressible lubricant (air) has been solved using finite element formulation. Further, separate finite element formulations have been carried out to compute fluid film stiffness and damping coefficients directly. This method provides quick computation of stiffness and damping coefficients of aerostatic thrust bearing than the usual approach.
Design/methodology/approach
As the Reynolds equation governing the flow of compressible lubricant is nonlinear partial differential equation, the computation of the stiffness and damping coefficient follows an iterative procedure. It requires a lot of computational energy. Therefore, in the present work, a novel technique based on finite element formulation is suggested to compute air film stiffness and damping coefficient in aerostatic thrust bearing.
Findings
A novel technique based on finite element formulation is illustrated to simulate the performance of tilted pad aerostatic thrust bearing. On the basis of simulated results, following key conclusions may be drawn. The static and dynamic performance of a circular aerostatic tilted thrust pad bearing is significantly affected with a change in the value of tilt parameter and the shape of the recess.
Research limitations/implications
Implications are as follows: direct computation of air film damping coefficient is performed without perturbation method in finite element method (FEM); influence of tilt on aerostatic thrust bearing is studied; influence of recess shape on aerostatic thrust bearing is observed; and finite element formulation of aerostatic thrust bearing is performed.
Originality/value
The present work will be quite useful for bearing designer and academicians.
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Zhenshun Li, Jiaqi Li, Ben An and Rui Li
This paper aims to find the best method to predict the friction coefficient of textured 45# steel by comparing different machine learning algorithms and analytical calculations.
Abstract
Purpose
This paper aims to find the best method to predict the friction coefficient of textured 45# steel by comparing different machine learning algorithms and analytical calculations.
Design/methodology/approach
Five machine learning algorithms, including K-nearest neighbor, random forest, support vector machine (SVM), gradient boosting decision tree (GBDT) and artificial neural network (ANN), are applied to predict friction coefficient of textured 45# steel surface under oil lubrication. The superiority of machine learning is verified by comparing it with analytical calculations and experimental results.
Findings
The results show that machine learning methods can accurately predict friction coefficient between interfaces compared to analytical calculations, in which SVM, GBDT and ANN methods show close prediction performance. When texture and working parameters both change, sliding speed plays the most important role, indicating that working parameters have more significant influence on friction coefficient than texture parameters.
Originality/value
This study can reduce the experimental cost and time of textured 45# steel, and provide a reference for the widespread application of machine learning in the friction field in the future.
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The purpose of this paper is to study theoretically the combined influence of journal misalignment and wear on the performance of a hole‐entry hybrid journal bearing system. The…
Abstract
Purpose
The purpose of this paper is to study theoretically the combined influence of journal misalignment and wear on the performance of a hole‐entry hybrid journal bearing system. The bearing is assumed to be operating in a turbulent regime.
Design/methodology/approach
The modified Reynolds equation based on Constantinescu lubrication theory has been solved by using finite element method together with orifice and capillary restrictors flow equations as a constrain together with appropriate boundary conditions.
Findings
It has been observed that for a symmetric hole‐entry journal bearing configuration the value of h¯min is more for the bearing compensated by orifice restrictor as compared to capillary restrictor when bearing operates in turbulent regime under worn/unworn conditions. From the point of view of stability threshold speed ω¯th, the reduction in the value of ω¯th for capillary compensated bearing is around −3.89 percent whereas for orifice compensated bearing it is −7.85 percent when misaligned worn bearing is operating in turbulent regime.
Originality/value
The present work is original of its kind, in case of misaligned hole‐entry worn journal bearing. The results are quite useful for the bearing designer.
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Sanjay Rangrao Pawar and Vikas M. Phalle
Hybrid conical journal bearings have received great attraction by design engineers and researchers due to their incomparable performance. However, performance of these bearings is…
Abstract
Purpose
Hybrid conical journal bearings have received great attraction by design engineers and researchers due to their incomparable performance. However, performance of these bearings is affected due to wear. This paper aims to present an analytical study concerning the performance of hole entry worn hybrid conical journal bearings.
Design/methodology/approach
The Reynolds equation governing the flow of lubricant in the clearance space along with the restrictor flow equations has been solved using finite element method.
Findings
The numerically simulated results of worn bearing performance parameters indicate significant change in the performance due to wear. Therefore, for semi cone angle γ = 25°, the value of C¯22 reduces by 24.6 per cent at the wear value of about 50 per cent of radial clearance for the given configuration of bearing.
Originality/value
The present results are original of its kind and surely useful to bearing designers and researchers in predicting actual performance of worn hole entry hybrid conical journal bearing.