Thermohydrodynamic Analysis of Journal Bearings Lubricated by Non-Newtonian Fluids—Theory and Experiments
01 Sep 1994-Vol. 208, Iss: 3, pp 173-181
TL;DR: In this paper, a rotary shear viscometer was used to measure the effect of test parameters on the performance of a journal bearing lubricated with different types of non-Newtonian fluids.
Abstract: Viscosity index improvers cause the lubricants to exhibit non-Newtonian flow behaviour and display shear thinning and normal stress differences. Shear thinning behaviour is studied by using a rotary shear viscometer. Owing to the non-availability of a rheogoniometer (for the measurement of normal stress differences), the first normal stress difference is calculated from the viscometric data using the Carreau viscosity function. The influence of the first normal stress difference on the hydrodynamic lubrication is analysed and shows that most of the commercial oils are inelasticoviscous in nature. Regression analysis shows that a large number of commercial lubricants follow the inelasticoviscous cubic law fluid model. Hence the cubic law fluid model is considered for the theoretical analysis.An experimental programme is developed to measure the effect of test parameters on the performance of a journal bearing lubricated with different types of non-Newtonian fluids. The experiments mainly include the measur...
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TL;DR: In this article, an experimental investigation has been carried out on the steady state and dynamic performance characteristics of a tilting pad journal bearing, which has been made using a thermocouple measuring system.
13 citations
TL;DR: In this paper, the effects of operation and design parameters of a journal bearing on power loss were investigated and a simplified estimator was proposed to estimate the power loss of journal bearings.
Abstract: Many journal bearings exist in an engine. Therefore, the effects of operation and design parameters of a journal bearing on power loss are the important information. In this study, simplified estim...
4 citations
15 Dec 2020
TL;DR: In this paper, a finite length cylindrical journal bearing working with non-Newtonian lubricant was modeled and analyzed numerically considering the effect of parameters such as nonlinearity behavior of the working fluid, cavitation, and the bearing liner elasticity.
Abstract: Journal bearings work under severe conditions of speeds and loads are far away from working at Newtonian condition due to the high shearing rate of the fluid in this case with cavitation at its divergent zone. The main goal of the present work is to study the journal bearing performance considering combined effects of nonlinearity behavior of the working fluid, cavitation, and the bearing liner elasticity. For this purpose, a finite length cylindrical journal bearing working with nonNewtonian lubricant modeled and analyzed numerically considering the effect of parameters. The analysis was implemented by solving the main governing equations using a suitable prepared computer program. The flow of lubricant assumed laminar, incompressible, and isothermal. Lubricant shear stress assumed to vary with a shear rate according to the power law with index coefficient (λ) varies from 0.7 to 1.3 while the cavitation effect included by implements Elrod's cavitation algorithm (ECA). The elastic deformation is considered by calculating the radial component of the bearing liner elastic deformation which is a function of the elasticity coefficient κ. Different parameters investigated in static analyses and the numerical model validated by comparing the results of pressure and density ratio obtained in the present work with that obtained by Ye et al., (1994) and they are found in a good agreement. The results obtained showed an increase in oil film pressure and the load carried by the bearing while the coefficient of friction decreases when the bearing lubricated with a non-Newtonian lubricant of a higher index. © 2020 Published by Faculty of Engineering * Corresponding author: Mushrek A. Mahdi E-mail: msb.mushrek.alawi@uobabylon.edu.iq Received: 5 September 2020 Revised: 2 November 2020 Accepted: 21 November 2020
2 citations
Cites methods from "Thermohydrodynamic Analysis of Jour..."
...[2] analyzed theoretically and experimentally the influence of the first normal stress difference on hydrodynamic lubrication using a cubic law fluid model for the mathematical model....
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21 Dec 2022-Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology
TL;DR: Abrasive water jet machining (AWJM) is an advanced machining process that has a variety of applications, including machining of hard-to-machine materials, drilling, milling, coating removal, polishing, etc as mentioned in this paper .
Abstract: Abrasive Water Jet Machining (AWJM) is an advanced machining process that has a variety of applications, including machining of hard-to-machine materials, drilling, milling, coating removal, polishing, etc. They are attractive because of their versatility, absence of heat-affected zones, low thermal-distortions, low cutting-forces, and environment-friendly nature. However, use of plain-water in AWJM poses some problems due to lack of jet coherence, poor suspension characteristics, and unsatisfactory performances in submerged-cutting and cutting of hollow surfaces. Countering these problems appropriately can lead to better cutting performances in terms of material removal rate, depth of cut, kerf-width, and kerf-taper. It can be achieved with addition of some additives in abrasive water-jet. These additives are mostly polymers of high molecular mass, which increases viscosity, suspension capability, and stability of jet, while reducing drag. In addition to AWJM, the effect of polymeric-additives in other water-based jets like Abrasive-Slurry-Jet (ASJ), High-pressure ASJ, etc. are also discussed. Therefore, this study aims to identify and list of different additives that are used in AWJM and other water-jet-based machining-processes over a past few decades, and to provide a run-through on their performances. It can provide the significant information to researchers working in fields related to waterjets.
1 citations
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TL;DR: In this paper, the effects of dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. And the experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction.
Abstract: Drag reduction by dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. The experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction. This work has application to increased pipelines capacity, the study of wall turbulence and molecular rheology.
1,010 citations
TL;DR: In this article, the authors discuss thermohydrodynamique theorique and experimental d'un palier de longueur finie, l'analyse tenant compte du transfert de chaleur entre le film, L'arbre, le manchon, la cavitation, la recirculation du lubrifiant, and the recurrence du lube.
Abstract: Etude du probleme thermohydrodynamique theorique et experimental d'un palier de longueur finie, l'analyse tenant compte du transfert de chaleur entre le film, l'arbre, le manchon, la cavitation, la recirculation du lubrifiant etant prise en consideration. Mesure de la distribution de pression et de temperature le long de la paroi du palier ainsi que du rapport d'excentricite et du debit pour differentes vitesses et differentes charges. Bon accord entre resultats experimentaux et theoriques
221 citations
102 citations
TL;DR: In this paper, a relation between the primary normal stress function and the shear viscosity function was proposed based on a single integral constitutive equation with a strain-dependent memory function.
Abstract: Based on a single integral constitutive equation with a strain-dependent memory function, a relation between the primary normal stress functionθ and the shear viscosity functionη is proposed. According to this theory, the primary normal stress functionθ can be obtained from viscosity data by simple differentiation of the viscosity functionη with respect to the shear rate
$$\dot \gamma$$
, and multiplication by a factor (−1/n). The material parametern is thereby associated with the strain dependence of the memory function. This relation was compared with the viscosity and primary normal stress data of six polymer melts, three polymer solutions, and an aluminium-soap solution, which were measured by several research groups and are available in the literature. In spite of the vast differences in physical constitution and chemical structure of the melts and solutions considered, agreement between predicted and measured values was encouraging.
86 citations
TL;DR: In this article, a relatively simple journal bearing rig was used to test the elasticity of viscoelastic lubricants and showed that the extra benefit of elasticity is much greater than that predicted by existing theory.
Abstract: Experiments have been carried out on a relatively simple journal bearing rig to test the theory that extra load-carrying capacity is generated the elasticity of viscoelastic lubricants. Model lubricants were used. The viscoelastic lubricants were solutions of high-molecular-weight polyisobutene in low-molecular-weight polyisobutene while the inelastic lubricant was low-molecular-weight polyisobutene. The extra load-carrying capacity has been established. An analysis of the detailed results strongly indicates that the extra benefit of elasticity is much greater than that predicted by existing theory. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in San Diego, California, October 22–24, 1984
28 citations