Tribology in Machine Components
01 Jan 2013-pp 821-879
TL;DR: Some of the results pertaining to the current issues of research, which needs to be considered for an accurate and realistic design of hydrostatic/hybrid journal bearing system, such as the number of recesses, type of restrictor, shape of recess, influence of turbulence and flexibility, etc are discussed.
Abstract: Proper tribological practices are extremely important from the view point of reliable and maintenance free operation of machine components. Friction, wear, and lubrication are three main domains of tribology. Proper interfacing among these domains is essential to have a better performance of machine components. Bearings are most critical machine elements which imparts constrained relative motion between two machine components. Bearings either have sliding contact or rolling contact. In the present chapter different types of bearings have been discussed. The main focus of this chapter is on hydrostatic/hybrid fluid-film journal bearings. The components of the hydrostatic/hybrid bearing system that have significant impact on bearing performance have been described. The analysis of fluid-film journal bearings and their performance characteristics parameters have been discussed. The chapter also discusses some current research trends in the design of hydrostatic/hybrid journal bearings. In concluding section the chapter discusses some of the results pertaining to the current issues of research, which needs to be considered for an accurate and realistic design of hydrostatic/hybrid journal bearing system, such as the number of recesses, type of restrictor, shape of recess, influence of turbulence and flexibility, etc.
Citations
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TL;DR: In this article, a powder metallurgy route was used to strengthen pure tin and improve its dry sliding resistance, and fabricated composites of Sn/SiC and Sn/Zn composites were compared to those of Sn-7.5Sb-3.5Cu Babbitt alloy.
8 citations
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TL;DR: In this paper, the authors derived equations of motion, constitutive equations and boundary conditions for a class of fluids named micropolar fluids, which respond to micro-rotational motions and spin inertia and therefore can support couple stress and distributed body couples.
Abstract: : Equations of motion, constitutive equations and boundary conditions are derived for a class of fluids named micropolar fluids. These fluids respond to micro-rotational motions and spin inertia and therefore can support couple stress and distributed body couples. Thermodynamical restrictions are studied in detail and field equations are obtained for the density, velocity vector and micro-rotation vector. The system is solved for a channel flow exhibiting certain interesting phenomena.
2,256 citations
281 citations
TL;DR: In this paper, a study of the performance parameters for a journal bearing of finite length lubricated with micropolar fluids is undertaken. And it is shown that a significantly higher load carrying capacity than the Newtonian fluids may result depending on the size of material characteristic length and the coupling number.
Abstract: A study of the performance parameters for a journal bearing of finite length lubricated with micropolar fluids is undertaken. Results indicate that a significantly higher load carrying capacity than the Newtonian fluids may result depending on the size of material characteristic length and the coupling number. It is also shown that although the frictional force associated with micropolar fluid is in general higher than that of a Newtonian fluid, the friction coefficient of micropolar fluids tends to be lower than that of the Newtonian.
128 citations
"Tribology in Machine Components" refers methods in this paper
...The modified Reynolds equation for journal bearings operating with micropolar lubricant is given as follows [25, 26, 43–45]...
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TL;DR: In this article, the effect of bearing wear on turbine bearing lubrication at low operating speeds has been investigated by conducting site visits to inspect used bearings during overhaul disassemblies, by interviewing the turbine manufacturers and technical personnel at selected utilities, and by performing an analysis of the effect on bearing wear.
Abstract: The subject of wear of steam turbine bearings at low operating speeds was addressed by conducting site visits to inspect used bearings during overhaul disassemblies, by interviewing the turbine manufacturers and technical personnel at selected utilities, and by performing an analysis of the effect of bearing wear on lubrication at low operating speeds. There is a general lack of understanding of the mechanisms of bearing wear, but there is universal agreement that maintaining proper alignment and minimizing debris in the lubricant are critical to obtaining long bearing life. Wear problems definitely exist, but there is a variation in level of concern regarding these problems. Lift pumps systems on turbines using a low turning gear speed were not found to eliminate bearing wear. Many of the wide variations in bearing design philosophies regarding bearing wear appear to be related to the need for reliable wear-related design data. An analysis of lubrication at low speeds has shown that a limited amount of bearing wear may enhance bearing lubrication and that an optimum in the extent of this wear may exist. Experimental data are needed to develop an understanding of bearing wear mechanisms and bearing operation at low speeds.
114 citations
"Tribology in Machine Components" refers background in this paper
...[34] proposed an abrasive wear model for the analysis of journal bearing system....
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TL;DR: In this article, hole-entry bearing configurations are compared with other bearing configurations for good load support and low energy consumption, when used in any of the four modes of operation including: zero-speed hydrostatic mode, high-speed hydrodynamic mode, zero and high speed hybrid mode; and jacking mode where areas are pressurised for start-up.
90 citations