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  • Other Sources  (9)
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  • 1
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    On the mixture flow problem in lubrication of hydrodynamic bearings - Small solid volume fraction (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The lubrication problem of infinitely long slider bearings with a mixture of fluid and particulate solid at small volume fraction level is studied. Closed-form analytical solutions for pressure and shear stress are obtained for a class of solid aggregates. The results reduce to those of pure fluid in the limiting case. A parametric study of the bearing performance with particulate solid is presented.
    Keywords: MECHANICAL ENGINEERING
    Type: STLE Tribology Transactions (ISSN 0569-8197); 35; 45-52
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  • 2
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    On the solution of a lubrication problem with particulate solids (1991)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The lubrication characteristic of a fluid with solid particles is studied using the continuum theory of mixtures. The governing equations are formulated and appropriate boundary conditions are introduced for an arbitrary-shaped lubricant film thickness. As a special case, closed-form analytical perturbation solutions for pressure and shear stress are obtained for a mixture of a conventional oil and solid particles with small values of solid-volume fraction sheared in the clearance space of an infinitely long slider bearing. It is found that when compared with a pure fluid, the mixture of the fluid and solid generates a higher pressure and therefore a higher load-carrying capacity with the added advantage of a reduction in the coefficient of friction.
    Keywords: MECHANICAL ENGINEERING
    Type: International Journal of Engineering Science (ISSN 0020-7225); 29; 9, 19; 1019-103
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  • 3
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    Thermodynamic analysis of journal bearings operating under steady state loading in laminar regime (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Thermohydrodynamic effects in journal bearings operating under steady load in laminar regime are investigated. An analytical model for the finite and infinitely long journal bearings is formulated. The model includes correction factors for the cavitation effects in the unloaded region of the bearing and the mixing of the recirculating oil and supply oil at the oil inlet. A finite difference computer program is developed to numerically solve the governing equations of the continuity, Reynolds, energy, Laplace heat conduction, and a viscosity-temperature relation simultaneously. The program includes a numerical technique for obtaining an isothermal shaft temperature. The numerical results of temperature distribution and the heat effects on the bearing load carrying capacity agree closely with those of experimental findings. Several different sets of simpler boundary conditions for the energy equation are studied.
    Keywords: MECHANICAL ENGINEERING
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  • 4
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    On the performance of finite journal bearings lubricated with micropolar fluids (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: 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 characteristics 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.
    Keywords: MECHANICAL ENGINEERING
    Type: STLE Tribology Transactions (ISSN 0569-8197); 32; 155-160
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  • 5
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    Effect of shaft frequency on cavitation in a journal bearing for noncentered circular whirl (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effect of shaft frequency on the performance of a submerged journal undergoing noncentered circular whirl is examined. The main emphasis of the paper is on the behavior of the vapor cavitation bubble and its effect on the bearing performance as a function of frequency. A cavitation algorithm due to Elrod was implemented in a computer program which solves a time-dependent Reynolds equation. This algorithm automatically handles the boundary conditions by using a switch function and a control volume approach which conserves mass throughout the entire flow. The shaft frequencies in this investigation ranged from 0 rad/s (squeeze-film damper) to -104 rad/s (a case in which oil-whip condition was produced momentarily). For the particular vibration amplitude chosen in this investigation it was observed that vapor cavitation had an effect on the load components for the full range of shaft frequencies investigated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-88925 , E-3361 , NAS 1.15:88925 , USAAVSCOM-TR-86-C-41
    Format: application/pdf
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  • 6
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    Current research in cavitating fluid films (1990)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A review of the current research of cavitation in fluid films is presented. Phenomena and experimental observations include gaseous cavitation, vapor cavitation, and gas entrainment. Cavitation in flooded, starved, and dynamically loaded journal bearings, as well as squeeze films are reviewed. Observations of cavitation damage in bearings and the possibility of cavitation between parallel plates with microasperities were discussed. The transcavity fluid transport process, meniscus motion and geometry or form of the film during rupture, and reformation were summarized. Performance effects were related to heat transfer models in the cavitated region and hysteresis influence on rotor dynamics coefficients. A number of cavitation algorithms was presented together with solution procedures using the finite difference and finite element methods. Although Newtonian fluids were assumed in most of the discussions, the effect of non-Newtonian fluids on cavitation was also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-103184 , E-4924 , NAS 1.15:103184 , AD-A230773
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  • 7
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    On the performance of finite journal bearings lubricated with micropolar fluids (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-100293 , E-3939 , NAS 1.15:100293 , AVSCOM-TR-88-C-001 , AD-A192057
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  • 8
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    Stability of a rigid rotor supported on flexible oil journal bearings (1988)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: This investigation deals with the stability characteristics of oil journal bearings, including the effect of elastic distortions in the bearing liner. Graphical results are presented for (1) steady-state load, (2) stiffness and damping coefficients, and (3) the stability. These results are given for various slenderness ratios, eccentricity ratios, and elasticity parameters. The lubricant is first assumed to be isoviscous. The analysis is then extended to the case of a pressure-dependent viscosity. It has been found that stability decreases with increase of the elasticity parameter of the bearing liner for heavily loaded bearings.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 87-TRIB-48 , ASME, Transactions, Journal of Tribology (ISSN 0742-4787); 110; 181-187
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  • 9
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    A continuum theory of a lubrication problem with solid particles (1993)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: The governing equations for a two-dimensional lubrication problem involving the mixture of a Newtonian fluid with solid particles at an arbitrary volume fraction are developed using the theory of interacting continuua (mixture theory). The equations take the interaction between the fluid and the particles into consideration. Provision is made for the possibility of particle slippage at the boundaries. The equations are simplified assuming that the solid volume fraction varies in the sliding direction alone. Equations are solved for the velocity of the fluid phase and that of the solid phase of the mixture flow in the clearance space of an arbitrary shaped bearing. It is shown that the classical pure fluid case can be recovered as a special case of the solutions presented. Extensive numerical solutions are presented to quantify the effect of particulate solid for a number of pertinent performance parameters for both slider and journal bearings. Included in the results are discussions on the influence of particle slippage on the boundaries as well as the role of the interacting body force between the fluid and solid particles.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME, Transactions, Journal of Applied Mechanics (ISSN 0021-8936); 60; 1; p. 48-58.
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