Showing papers by "Satish C. Sharma published in 2017"
01 Mar 2017
TL;DR: In this article, the combined influence of textured surface and couple stress lubricant behavior on the performance of circular/two-lobe slot-entry hybras has been investigated with theoretical investigation.
Abstract: This paper concerns with theoretical investigation to predict the combined influence of textured surface and couple stress lubricant behavior on the performance of circular/two-lobe slot-entry hybr...
18 citations
TL;DR: In this article, the influence of geometric irregularities on the performance of membrane compensated four pocket journal bearing under misaligned conditions is examined and the unknown fluid film pressure field in governing Reynolds equation is obtained by FE analysis using Gallerkin's technique.
14 citations
01 Jun 2017
TL;DR: In this article, the influence of recess geometry and method of compensation on the performance of recessed hydrostatic circular thrust pad bearing was investigated with the theoretical investigation to show the influence.
Abstract: This study concerns with the theoretical investigation to show the influence of recess geometry and method of compensation on the performance of recessed hydrostatic circular thrust pad bearing ope...
14 citations
TL;DR: In this paper, the behavior of smart lubricants is described by Bingham model of non-Newtonian fluid flow, which provides better dynamic behavior than conventional lubricants and hence is more suitable for the application of fluid film bearings.
Abstract: Lubrication of fluid film bearings with smart lubricants provides better dynamic behavior. The behavior of these smart lubricants is described by Bingham model of non-Newtonian fluid flow. In the r...
10 citations
TL;DR: In this article, the combined influence of textured surface and micropolar lubricant behavior on the performance of a two-lobe hole-entry hybrid journal bearing system was studied.
Abstract: Purpose
The aim of the present paper is to study the combined influence of textured surface and micropolar lubricant behaviour on the performance of two-lobe hole-entry hybrid journal bearing system. The bearing performance parameters of the textured circular/two-lobe hole-entry hybrid journal bearing system have been computed against the constant vertical external load supported by the bearing.
Design/methodology/approach
In this work, Eringen’s micropolar fluid theory has been used to derive the governing Reynolds equation. The consequent solution of the governing Reynolds equation has been obtained by using finite element method (FEM) numerical technique.
Findings
The present study indicates that the use of the textured surface, two-lobe profile of bearing and micropolar lubricant, significantly enhances the bearing performance as compared to non-textured circular journal bearing.
Originality/value
The present study concerning the influence of surface texturing on the behaviour of the two-lobe hole-entry hybrid journal bearing lubricated with micropolar lubricant is original. The theoretically simulated results of the present study will be useful to design an efficient journal bearing system.
8 citations
TL;DR: In this paper, the combined influence of couple stress lubricant and tilt between bearing pad surfaces, on the performance of externally pressurised annular recess thrust pad bearing was investigated with a MATLAB code.
Abstract: This paper concerns with the theoretical investigation to predict the combined influence of couple stress lubricant and tilt between bearing pad surfaces, on the performance of externally pressurised annular recess thrust pad bearing. Stokes micro-continuum theory is used to derive modified Reynolds equation accounting for the presence of couple stress additives in lubricant. A MATLAB code has been developed to solve the governing equation using FEM technique. Influence of annular recess location and tilt between pad surfaces are investigated on the performance of hydrostatic thrust pad bearing. It has been observed that the use of couple stress lubricant significantly improves the performance of annular recessed hydrostatic thrust pad bearing. Presence of tilt between bearing surfaces proved to be beneficial in terms of dynamic characteristics of bearing system.
8 citations
TL;DR: In this article, a mathematical model for the propagation of an intense laser pulse in a plasma having Gaussian profile is investigated, and the model has been formulated considering that the relativistic-ponderomotive nonlinearity dominates over other nonlinearities in the plasma.
Abstract: The mathematical model for the propagation of intense laser pulse in a plasma having Gaussian profile is investigated. The model has been formulated considering that the relativistic–ponderomotive nonlinearity dominates over other nonlinearities in the plasma. Model equation for self-compression and self-focusing properties of the laser pulse has been set up and solved by both semi-analytical and numerical methods. The result indicates that due to the effect of group velocity dispersion, diffraction of the laser pulse and the nonlinearity of medium, the pulse width parameter as well as beam width parameter of pulse gets focused at a different normalized distance, and hence the normalized intensity is also deferred at those points. Numerical simulation shows an oscillatory behavior of intensity during propagation in the plasma either having minimum beam radius (r 0) or having minimum pulse duration (t 0) depending on the normalized distance.
7 citations
TL;DR: In this article, the influence of couple stress lubricant on the circular and non-circular hole-entry hybrid journal bearing system was investigated and the numerically simulated results indicated that the influence was significantly more in textured journal bearing than that of non-textured bearing.
Abstract: Textured surface in journal bearings is becoming an important area of investigation during the last few years. Surface textures have the shapes of micro-dimple with a small diameter and depth having order of magnitude of bearing clearance. This paper presents the influence of couple stress lubricant on the circular and non-circular hole-entry hybrid journal bearing system and reports the comparative study between the textured and non-textured circular/non-circular hybrid journal bearing system. The governing Reynolds equation has been modified for the couple stress lubricant flow in the clearance of bearing and journal. The FEM technique has been applied to solve the modified Reynolds equation together with restrictor flow equation. The numerically simulated results indicate that the influence of couple stress lubricant is significantly more in textured journal bearing than that of non-textured journal bearing. Further, it has been observed that the textured two-lobe (δ = 1.1) hybrid journal bearing lubricated with couple stress lubricant provides larger values of fluid film stiffness coefficients and stability threshold speed against other bearings studied in the present paper.
6 citations
TL;DR: In this article, a non-uniform perturbation superimposed on a plane-wave pump is considered, such that a finite intensity gradient arises and gives rise to ponderomotive force.
Abstract: Filamentation is one of the most common nonlinear phenomena taking place in the laser–plasma interaction that splits the laser beam into high-intensity spikes. The present study deals with the nonlinear evolution of filamentation instability in laser–plasma interaction and the development of chaos in contrast to linear growth as reported by Kaw et al. in 1973. We have considered a non-uniform perturbation superimposed on plane-wave pump such that due to non-uniformity of the perturbation a finite intensity gradient arises and gives rise to ponderomotive force. This causes filamentation of wave, which has been studied presently using numerical methods as well as analytical tools. The results reveal that the intensity of perturbation gets localized and delocalized with the distance of propagation. The numerical simulation results also reveal that the intensity of perturbation route from ordered to chaotic behavior depending upon the pump laser and perturbation parameters. To study the chaotic behavior, Lyapunov exponents has also been calculated. The semi-analytical method is also developed to have an insight into some of the features of simulation like the formation of localized structures.
6 citations
TL;DR: In this article, the effect of surface roughness orientation pattern on the nonlinear transient response of symmetric two-lobe capillary compensated hole entry hybrid journal bearing is described. But the results of the study reveal that the surface roughs pattern significantly changes the stability of capillary-compensated two-leafered journal bearing, and hence, a proper selection of the roughness pattern and bearing geometry is essential.
Abstract: The present paper describes the effect of surface roughness orientation pattern on the nonlinear transient response of symmetric two lobe capillary compensated hole entry hybrid journal bearing. Nonlinear equations of motion have been solved with the Runge-Kutta method. The stability of the journal bearing system has been studied by obtaining the journal center motion trajectories. The results of the study reveal that the surface roughness pattern significantly changes the stability of capillary compensated two lobe hole entry hybrid journal bearing. Hence, from the bearing stability point of view, a proper selection of the surface roughness pattern and bearing geometry is essential.
5 citations
TL;DR: In this article, a novel technique based on finite element formulation is suggested to compute air film stiffness and damping coefficient in aerostatic thrust bearing for different geometries of recess.
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.
01 Jul 2017
TL;DR: In this article, the linear and nonlinear transient motion analysis of a 2-lobe geometrically imperfect hybrid journal bearing system compensated with constant flow valve restricher was performed.
Abstract: The present study is concerned with the linear and nonlinear transient motion analysis of a 2-lobe geometrically imperfect hybrid journal bearing system compensated with constant flow valve restric...
TL;DR: In vitro bioassay of the seventy rhizobacterial isolates revealed that the isolate I-58 was the most effective rhizOBacterial isolate, followed by I-30 and I-55 isolates in inhibiting the radial growth of test pathogens.
Abstract: Studies were carried out from 2013 to 2015 with the objectives to isolate and identify some indigenous rhizobacterial strains against major soil-borne pathogens of brinjal. Seventy thizobacterial isolates were characterized based on colony characters, morphological and biochemical test and identified as Pseudomonas flourescens (30), P. aeruginosa (13), P. aureofaciens (2) and Bacillus subtilis (25). In vitro bioassay of the seventy rhizobacterial isolates revealed that the isolate I-58 was the most effective rhizobacterial isolate, followed by I-30 and I-55 isolates in inhibiting the radial growth of test pathogens.
TL;DR: Thirty one wheat germplasm lines screened under natural epiphytotic conditions against stripe rust at University Research Farm, Chatha, during Rabi, 2014-15 exhibited partial resistance to the disease while one genotype (Agra Local) was susceptible.
Abstract: Thirty one wheat germplasm lines were screened under natural epiphytotic conditions against stripe rust at University Research Farm, Chatha, during Rabi, 2014-15. On the basis of final rust severity (FRS), area under rust progress curve (AURPC) and coefficient of infection (CI), eight lines (Raj 4037, Sonara 64, NP 823, HPW 42, K9351, NIAW 301, PBW 12, and HUW 213) exhibited partial resistance to the disease while as on the basis of infection rate (r) six lines (NP 825, HP 1633, K8434, PBW 12, Ajanta and K9533) showed partial resistance to the disease. Field response of these lines against stripe rust showed that 14 genotypes (Sonara 64, Utkalia, NI 5439, NIAW 301, PBW 12, HUW 213, Ajanta, NP 823, K8434, K9533, Sharbati Sonara, Raj 4037, HP 1633, HPW 42 and K9351) were moderately resistant, 16 (Tawa, KRL, RW 346, HD 2643, HS 1097, NP 825, WH 291, HUW 12, PBW 226, NI 179, NI 5439, K9644, HD1925, PBW 65, PV 18 and GW 503) were moderately susceptible and one genotype (Agra Local) was susceptible. Assessment of losses was also calculated at different growth stages and it was observed that losses at flowering stage and dough stage were highest in one line (Agra Local). Nine wheat germplasm lines (Sonara 64, K9351, HP 1633, Raj 4037, Sharbati Sonara, K9533, K8434, NP 823 and Ajanta) amplifying a band of 523 bp fragment indicating presence of Yr18 gene.
TL;DR: In this article, the performance of the two-lobe and circular hybrid journal bearing system compensated with membrane restrictor has been compared with the non-Newtonian behaviour of the lubricant and the Stokes couple stress fluid model.
Abstract: This paper deals with the comparative performance of the two-lobe and circular hybrid journal bearing systems compensated with membrane restrictor. The combined influence of geometric imperfection of journal and the couple stress behaviour of the lubricant has been taken into the consideration. The non-Newtonian behaviour of the lubricant has been modelled using Stokes couple stress fluid model. The Reynolds equation has been modified to consider the couple stress fluid behaviour and has been solved by the FE Galerkin's approach. The numerically computed results from present study indicates that the couple stress lubricant presents an improved bearing performance in terms of stability (threshold speed), fluid film stiffness and damping coefficients vis-a-vis the corresponding bearing lubricated with Newtonian fluid. Further, the comparative performance of this class of bearings has been evaluated for the capillary, orifice and CFV restrictors.